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T53 AND T55 GAS TURBINE COMBUSTOR ANDENGINE EXHAUST EMISSION MEASUREMENTS
Philip M. Rubins, et al
Avco Lycoming Division
Prepared for:
Army Air Mobility Research and DevelopmentLaboratory
December 1973
DISTRIBUTED BY:
.,,: National Technlul Information Service' !U. S. DEPARTMENT OF COMMERCE
:7!i} 5285 Port Royal Road, Springfield Va. 22151
DISCLAIMERS
The findings in this report are not to be construed as an officialDepartment of the Army position unless so designated by otber authorized ,documents.
When Government drawings, specifications, or other data are used for anypurpose other than in connection with a definitely related Governmentprocurement operation, the United States Government thereby incurs noresponsibility nor any obligation whatsoever; and the fact that theGovernment may have formulated, furnished, or in any way supplied thesaid drawings, specifications, or other data is not to be regarded byimplication or otherwise as in any manner licensing the holder or anyother person or corporation, or conveying any rights or permission, tomanufacture, use, or sell any patented invention that may in any way berelated thereto.
Trade names cited in this report do not constitute an official endorse-ment or approval of the use of such commercial hardware or software.
DISPOSITION INSTRUCTIONS
Destroy this report when no longer needed. Do not return it to theoriginator.
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SecuitY Classification
DOCUMENT CONTt(OE DATA - R &D(S&Cwity, eJ"taa"ficf n Of t~t~b, body of .tbatsat and And~xIng mionIOIh muot b.et hnhe o vhterod Wpott IS IsC188ae1I- ORIGINATING ACTIVTY (C4hpCW to auma) 28. REPORTlh 0SICURTY ASSIFICATIONAvco Corporation Ucasfe
Avco Lycoming Division ab. GROUP "
Stratford, Connecticut, y . REPORT TITLE
T53 AND T55 GAS TURBINE COMBUSTOR AND ENGINE EXHAUST EMISSIONMEASUREMENTS
4. DESCRIPTIVYE NOTESO(2rPaOi n md incluafw. defto)Final Report, June 1972 through February 19735.ATHORMS (PIVIC noan*, middle ilutalast llSam)
Philip M. RubinsBrian W. Doyle
4.PORT DATE 741. TOTAL NO. OF PAGES oA. NO la RpsDecember 1973 219 34
0. CONTRACT OR GRANT NO. S&ORIGINATOR-$ REPORT NUIRSERIS)DAAJO2-72-C-0102IPROJECT No,
USAAMRDL Technical Report 73-47cTask IG162207AA7102 Fb .HE EORT NO(S) (Any 60We ubq iatjasp be aa*Iald
LYC 73-810. ISTRISUTION STATEMENT-
Approved for public release; distribution unlimited,
31_____________ 12_ SOSOIN ILTAYACIVT
EustiF Directorate, U. S. Army Air mobility
Research and Development Laboratory, Frflustis, Virginia
t Extensive tests were made to determine the gaseous exhaust emission characteristics of T53-L-13A andT55-L-11A Lycoming gas turbine engines. In addition, the combustor for each en 'n " was testedsoiparately under laboratory conditions simulating engine operation. Data were anafyzed for the fullrange of enin power oprato frC, yroabns O NOx and CO2, and for smoke. Sampleswere taken with six-point traversing probes, a single-point traversing probe, and multiorifice averaging-type probes. Approximately 1500 data points were recorded, Results demionstrated that (1) laboratoryemission measurements are representative of engine exhaust measurements; (2) all tile three-probe
k sampling configurations produced similar results within 5 to 10 percent of each othert (3) results con-formed to accuracy specified by SAE-ARP 1256; (4) emnission characteristics of the engines show thatnther engine produces visible smoke, except when there is an obvious oil seal failure. Comparisons
with Navy test data on these engines show some differences. However, considering that the testdifferences included engine, instrumentation, time, place, and personnel, agreement Is considered to bequite good. Extensive profile data were ilotted. The "averaging" probe accuracy was found to bo
satisfactory and also has the advantage o a short-tinie sampling interval, as compared with lengthysingle-point traverses. Several exhaust emission problenms are analyzed and discussed.I
U S DepattmeInt of Cormouoa
Splgil VA 141
Ww" IV
UnclassifiedkSecurity Clasuufica-tion
14. LINK A LINKS5 LINK CKEY W4ROS -
ROLE WT ROLE WT ROLE WTY
T53-L-13A Gas Turbine EngineT55-L-11A Gas Turbine EngineExhaust Gas CompositonExhaust EmissionsEngine PerformanceEmissions in Gas Turbine ExhaustSmoke in Gas Turbine Exhaust
niission MeasurementLaboratory Combustor vs Engine EmissionsLaboratory Measurement To Prodict Engine Emissions
J
Al
Unclassified
UDEPARTMENT OF THE ARMYU. S. ARMYAIR MOBILITY RESEARCH & DEVELOPMENT LABORATORY
EUSYIS DIRECTORATEFORT EUSTIS, VIRGINIA 23604
The research described herein was conducted by Avco11 Lycoming Division under U.S. Army Contract DAAJ02-72-C-0102. The work was performed under the technicalmanagement of SP4 Charles R. Roehrig, TechnologyApplications Division, Eustis Directorate, U.S. ArmyAir Mobility Research and Development Laboratory.
The objective of this contractual effort was toobtain a sample of emission data on the T53-L-13Aand the T55-L-IIA engines. A prior emissioncharacterization program was run with the Navy tomeasure the gaseous emissions of the T63, T53, andT55 engines; however, a second sample was deemednecessary due to the wide engine-to-engine variationsthat occur in emission levels for a particular enginemodel. Tests were also planned to establish thecorrelaticns between (1) component and engine emission
// . data and (2) data taken with averaging and single-point4 v probes. The effort performed here is part of an overall
plan to establish the base-line emission levels ofpresent high-inventory Army aircraft engines.
Appropriate technical personnel of this directoratehave reviewed this report and concur with the conclusionscontained herein.
The findings and recommendations outlined herein will beconsidered in planning future emall gas turbine enginesand combustor component development programs.
4,
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in l n {I N~~lNN lm lI~ll U I n i l l • I C- n nnlu l n l I m un n nin n •nmn l
Task 1G162207AA710ZContract DAAJOZ-72-C-0OZ
tJSAAMRDL Technical Report '73-47
December 1973
T53 AND T55 GAS TURBINE COMBUJSTORAND ENGINE EXHAUST EMISSION MEASUREMENTS
Final Report
Avco Lycoming Report LYC 73-811By
Philip M. RubinsBrian W. Doyle
Prepared by
Avco Lycomning Division~iStratford, Connecticut-
for
EUSTIS DIRECTORATEU.S. ARMY AIR MOBILITY RESEARCH
AND DEVELOPMENT LABORATORYFORT EUSTIS, VIRGINIA
2W w fo pblc @-.
dAtbto unlimiAed
gmg
SUMMARY
This report is concerned with exhaust gas emission tests of LycomingT53-L-13 and T55-L-11 engines and combustors. These engines weredesigned in the 1960's, and exhaust emission was not a design criterionat th at-time., The purpose of the present tests was to evaluate the'engines and combustors from a pollutant standpoint and compare theresults with the current state of the art. Extensive tests were madeto determine the gaseous exhaust emission characteristics of both a
T53-L-13A and a T55-L-1A Lycoming gas turbine engine. In addition,the combustor for each engine was tested separately under laboratory
V conditions simulating engine operation, with similar measurements ofgaseous emissions. --Engines were selected from those available whichperformed within the guaranteed-range;. Data were analyzed for thefull range of engine power operation for CO, hydrocarbons, NO, NOx*and CO', and for smoke. Samples were taken with six-point traversingprobes, with a single-point traversing probe, and with multiorificeaveraging-type probes. -Approximately i 500 data points were recorded.
Results demonstrated that: .
- 1. Laboratory emission measurements are representative of engineexhaust measurements.
2. Single-point probe, multiorifice probe, and single-point probemeasurements in the same pattern configuration as the multiorificeprobe produce similar results within 5 to 10 percent of each other.
3. By comparing the engine or test rig fuel-air ratio with the gassample determined fuel-air ratio, we found the sample to be"representative" because the agreement was within 10 percent.[ !This is within the accuracy recommended by SAE-ARP 1Z56(specified 15 percent tolerancel..
4. Emission characteristics of the engines show: [jl a. Neither engine produces visible smoke, except when there.° is an obvious oil seal failure.
b. Trends of emittants CO, hydrocarbons, NO, and NO areas expected. Comparisons with Navy test data on tWeo
..... .... : ,iii
engines show some differences. However, consideringthat the test differences included engine, instrumentation,time, place, and personnel, agreement is considered to bequite good.
e.Extensive profile data plotted along diameters of the engine exhaust,around the circumference of the combustor exit plane, and as isoplethmaps are presented. .
Exhaust profiles for these engines were found to be uniform enoughso that an averaging-type probe of cruciform configuration willingest "representative" samples; that is, within 3 percent of the moredetailed and extensive single-point probe average. The averagingproba also has the advantage of sampling over a short time interval,as compared with lengthy single-point traverses. Small variationsover a long test period reduced some of the precision of multipointsampling.
Although not a specific objective of this program, the measurementsprovide (1) an insight into the combustion processes and (2) indicationsof ways in which the exhaust emission6 of the engine can be reduced.
1
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71 OW
___..... . ____ __________
FOREWORD
*The work was performed by AVCO Lycoming for the Eustis Directorate,
U.S. Army Air Mobility Research and Development Laboratoryunder Contract DAAJOZ-72-C-0102, Task 1G162207AA7102, as apart of evaluation of emission properties of gas turbine engines usedby the U.S. Army. The program monitor was Sp4 Charles R. Roehrig.
The authors acknowledge the significant contributions to this reportmade by the following members of Lycoming's Engineering Staff:
Messrs. J. Sweet and S. Osborn, who mauaged the test phase
Mr. J. Knight, who worked on the gas analyzer instrumentation
Mr. A. Myers, who performed the engine analysis work
Mr. G. Panas, who supervised the engine operation
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TABLE OF CONTENTS
SSUMMARY .. . .. . i....i
FOREWORD . . . . . . . . . . . . . . . v
LIST OF I1LUSTRATIONS . . . . . . . . . . . ix
LIST OF TABLES. . . . . ........ . xxi
LIST OF SYMBOLS . . ....... . . . xxii
INTRODUCTION ... .......... . 1
Objectives . . . . . . .Test Approach5
Expected Results . . . . . . . . . . . .. 6
DESCRIPTION OF TEST EQUIPMENT . ...... . 7
Laboratory Combustor Equipment .... • • • • 7Engine Test Equipment ....... . • • • 20Gas Analysis Equipment . ...... . . . . Z2Smoke Analyzer Equipment . . . ....... 31
PROCEDURES. .*. . ... . . ... . . . 34
Exhaust Gas Analysis Chemistry ..... 34Calculation Programs . . . . . . . • • • . 36Calibration of Instrumentation . . . . . . . . . 37Combvuitor Test Procedures . ....... • 42Engine Test Procedures . . . . .. • . • . • • 43Data Calculation and Initial Data Plots . . . . a . 44Ga.sAnalysisProblems . . . . . . . . . .4. 4
DISCUSSION OF DATA AND RESULTS . • . . . . . 56
Analysis of Precision of the Measuremefts . . . . . 56Test Results • • . • • • • • • . . • 79Correlations . .. . . . . 1 1 ' 0 - "
P n i1ai p e i RAN HNi
Page
COMPARISON OF LYCOMING AND NAVY EMISSIONS DATA*1FROM THE T53 AND TZ5 . . . . . . . . . . . . 129
Gas Analysis. . . . . . . . . . . . 129Comparison of Smoke Data Fromi Lycoming and Navy Tests *136
CONCLUSIONS AND RECOMMENDATIONS . . . . . . 138
LITERATUJRE CITED . .*.**.**.* . .. 140
APPENDIXESf
I. T53 Laboratory Combustor Rig Traverse Data 14II. T53 Engine Isopleth Exhaust Contour Plots . . . . . 1 58
III. T55 Engine Laboratory Conmbustor Rig Traverse Data .* 171IV. T55 Engine Isopleth Exhaust Contour Plots & 185
DISTRIBUTION, .. * 4 .. , 4 .198
viii
LIST OF ILLUSTRATIONS
Figure Page
1 Lycoming T53-L-1 3A Engine Cutaway, ShowingCombu.-tor Arrangement.....**..* * a
* 2 Lycoming T55-L-1 lA Engine Cutaway, ShowingCombustor Arrangement ........... a
.13 Combustor Laboratory Test Area, Showing CombustorTest Rig (Test Way 1) and Portable Engine Test Stand. 8
4 Compressor Control Panel . . . ...... 9
5 T53 Laboratory Combustor Test Rig in Test Way 1 . 9
6 T53 Combustor Test Rig, Curl and Rotating DrumAssembly, Showing Thermocouple Leads and FlexibleGas SamplingLines .. ........... 10
7 T53 Comnbustor Rig Gas Sampling Line for RotatingProbe * * * , * * * * * * * *. . . 10
8 T53 Combustor Rig, Showing Rotating Drum DriveGears, Gas Sampling Lines.* and Thermocouple Leds 11
9 Installation of Thermocouple and Gas Sampling Probesfor T53 Combustor Test ..... *. . 12
10 T5 5 Laboratory Combustor Test Rig in Test Way 1 13
I1I T55 Combustor Test Rig Hot End Assembly, Showing
Prossure Probes . . . .. . *~ 14
12 T55 Combustor Test Rig Curl and Rotating DrumAssembly. Showing Thermocouples and Flexible GasSampling Lines *. . . . * . * . 14
13 Installation of Thermocouple* and Gas Sampling Probesfor T55 Combustor Laboratory Test ***.... is K
Figure Page
14 Water-Cooled Rotating Gas Sampling Probe for T53Combustor Test . .. .... * .. 174
15 Water-Cooled Rotating Gas Sampling Probe for T55Comnbustor Test . . . . . . 17
16 Fixed-Position Gas Sampling Probes (IUncooled) for
T53 Comnbustor . . . . . . . . 18
17 Water-Cooled Fixed Gas Sampling Prob-. for T55Comnbustor Test . . . . . .. . . 18
18 DS-1O(A Gas Analyzer Console in Combustion Labora-tory an~d DS-8, Digital Recorder.. . .. . .. . 19
19 DS-5 Combustor Performance Digital Data Acquisitionand Control System .............. 19
ZO Intake End of T53 -L- 13A Engine Mounted on PortableTest Stand, Showing Water Brake and Control Room . 2
21T55 Engine Installed on Portable Test Stand, ShowingInlet and Water Brake (Power Supply Trailer is in theBackground) . of* .40 *Got#. ... . z
ZZ Dual Exhaust Averaging Gas Samplinq Probe (Gas andASmoke) for T53 or T55 Engines .... . Z3
Z3- Dual Exhaust Averaging Gas Sampling Probe for T55Engine . . . . . . . . . . . * * 24
Z4 T55 Engine on Test Stand With Averaging Gas SamplingProbeIn Place. . . . . . . . . 25
Z5 T53 Hrngine Installed on Portable Test Stand WithAveraging Dual Gas Sampling Probe (Actuator forTraversing ProbelIsin Place) . ..... .. 25
Z6 -Single-Point Gas Sampling Probe Used With Traversing* .1 Mechanism for T5:1 and T55 Zxhaust Sampling .*,. 26
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Figure Page
27 Single-Point Exhaust Gas Sampling Probe Installedon Actuator in T55 Engine Exhaust . . . . . . . 26
28 Location of Gas Sampling Points for T53 and T55Engine Exhaust . . . . . . . . . . ..... Z7
29 Schematic of the On-Line Gas Sampling System .. 29
f30 Schematic of the Lycoming Stained Filter Paper SmokeAnalyzer . . . . . . . . . . . . . . . . . . 32
* ~31 Lycoming Smoke Analyzer ........ .. 33
32 Hydrocarbon Calibration Correction Factor Versus* ~Pressure for Flame Ionization Detector .... . 39
33 Typical Calibration Trace for NDIR C02 Analyzer .. 40
34 Typical Calibrations, NDIR NO Analyzer HydrocarbonFID # * * * * * . .# e .* * * .* 40
35 Typical Calibration Trace for NDIR CO Analyzer. . 41
36 Typical Calibration Trace for Polarographic NOxAnalyzer . . . . . . . . . . . . . . . . . 41
37 Typical Chromatograph of JP-4 Fuel Compared toSpecial Calibration Mixture, Showing Many Componentsand Approximate Carbon Content ......... 47
-38 Vapor Pressure of Various Hydrocarbons VersusTemperacure and Concentration . .. ... 48
39 Correlation of Rig F'uel-Air Ratio With Gas AnalysisFuel-Air Ratio for Laboratory T53 and T55 Combustor. 60
40 Correlation of T53 Engine ruel-Air Rlatio With GasAnalysis Fuel-Air Ratio fiz T53 Engine . . . . 6
41 Correlation of T55 Engine Fuel-Air Ratio With GasAnalysis Fuel-Air Ratio . . ., .. .62
xi
Figure Pg
42 Water-Cooled Movable Gas Sampling Probes for T53and T55 Combustor Test After Test Completion(Overheating of the T55 probe caused damage
to the sampling ports) .... . . .. 63I
43 Fuel-Air Ratio from Gas Analysis Versus Time, T55
Center-Point Probe 65 ....
44 T53-L-13 Engine K-121J Performance Comparison
With 7400-Engine Sample. 70
45 T53-L-13 Engine K-12IJ Performance ComparisonjWith 7400-Engine Sample . ... .. 71
46 T53-L-13 Engine K-12IJ Low Power Performanc eComparison With 15-Engine Sample .. . . . . . . 72
47 T53-L-13 Engine K-121J Low Power PerformanceComparison With 15-Engine Sample . . . . . . . . 73
48 T55-L-11A Engine B-19Q Performance ComparisonWith 493-Engine Sample.. .. .. . 75
49 T55-L-11A Engine B-19Q Performance ComparisonWth 493-Engine Sampe. . . .. 76
so T55-L-11A Engine B-19A Performance ComparisonWth 5-Engine Sample.. ..... *.. 77
Aw51 T55-L-1 1A Engine B-1 9A Performance ComparisonWith 5-Engine Sample. 78
U T53 Combustor Rig Emissions Versus Fuel-Air Ratio(Crucform Probe). 81
53 Comparison of Average Traverse Temperature andFuel-Air R~atio From Gas Analysis -T53-L-1 3 RigSimulationof Idle 82......
xii
Figure Page_
54 Comparison of Average Traverse Temperature andFuel-Air Ratio for Gas Analysis -T53-L-13 RigSimulation of 30 Percent Power. 82
55 T53-L- 13 Rig Simulation of 60 Percent Power ... 83
36 T53-L-13 Rig Simulation of 100 Percent Power .. 83
57 T53-L-13 Engilie Emissions Versus Power (Cruciform- Probe) . . . . . . . . . . . . . . . . 86
F . T53 Engine Emissions Versus Fuel-Air Ratio . . . . 88
59 T53 Engine Idle Diametral Profiles ........ 89
60 T53 Engine 30-Percent Power Diametral Profiles . . , 9o
61 T53 Engine 60-Percent Power Diametral Profiles . . . 91
62 T53 Engine Maximum Pewer Diametral Profiles . . . 92
63 T53-L-13 Engine Combustion Efficiency VersusPercent Power .*.******** ***94
64 T53-L-13 Engino AlA Smoke Number Versus PercentPower . . . . . . . * . * . * . * . . . 94
65 Fuel-Air Rlatio Versus Probe Angular Position forT53 Engine and Comnbustor at Maximum Power . . . 96
66 Fuel-Air Ratio Versus Shaft Horsepower for T53Engine and-Combustor ......... .. 97
67 Comparison of T53-L-13 Emissions From Engine andLaboratory- Combustor Tests . .. * 98
68I T55 Laborator~y Combuastor Emissions Vorsus Fuel-AirRatio . . . . 0 0 S 0 0 S S S S 0 0 * 5 100
Xiii
Figure Page
69 T55-L-ll Rig Simulation of dle............ 101
70 T55-L-1l Rig Simulation of 30 Percent Power..... 102
71 T55-L-1l Rig Simulation of 60 Percent Power.***$**** 103
72 Comparison of Temperature and Fuel-Air Ratio forfor T55-L-11 Rig Simulation of 100%6 Power....*.****** 104
73 T55-L-ll Engine Emissions Versus Percent Power
(Cruciform. Probe).... .... ... .... .*.107 *74 T55-L-IlA Engine 470 Lb/Hr Idle Diametral Profiles.. 108
75 T55-L-11A Engine 30%6 Power Diametral Profiles..*$*$ 109
76 T55-L-11 Engine 607o Power Diametral Profiles... .. 110
77 T55-L-lIA Engine Diametral Profiles of Emittants
and Fuel-,?Air Ratio at Full Power s, * e e e so... s ill99 1
78 T55 Engine tsopleth of HC (ppmC) at 60 PerceritPower p~~.~ ~113
79 T55 Engine I: opleth of HC (pprnC) at 60 PercentPower Duing an OiSeal Faie.......... 113
80 T55 Engine Exluauot Hydrocarbon Concentration Withand Without Oi1 Sleal Leakage ............. 114
81 T55-L-1 IA Engine Combustion Effic'.ency Versus Per-
82 T55-L-11A Engine ALA Smoke Number Versus Percent
83 Fuel-Air Ratio Versus Probe Angular Position for T55Engine and Combustor at 60 Percent Power,s*,....... 118
84 Fuel-Air Ratio Versus Shaft Horsepower for T55 Engineand Combustor.a.*t.se...ose .. . e es..see.*at.sets* 119
xiv
Figure Page
85 T55-L-1LA Emissions Comparison of Engine toLaboratory Comnbustor Emissions ................... izo
86 Inlet Air Temperature Versus Nitric Oxide Emittedfor T53-L-l3 Engine.................. 1ZZ
87 Inlet Air Temperature Versus Nitric Oxide Emittedfor T55-L-ll Engine.......... S *.... to..... 0.. 0*. 123
88 NOx Versus Inlet Temperature for Several Large andSmall Gas Turbines Compared to T53 and T55iEmiissions . Ot . 0 . .*..*... *se 094 .0 .so .4 0 0000000# $ 12-5
89 Comparison of T53-L-13 Combustion Efficiency VersusFuel-Air Ratio for Engine and Laboratory Data.... 126
90 Comparison of T55-L-llA Combustor CombustionEfficiency Versus Fuel-Air Ratio for Engine and
Laboratory Data,. ......................... 01 .to .* to .0 .000 . .1 12.6
91 Comparison of Combustion Efficiency Data VariationVersus Power for CAL Report Engines and LycomingT53 and T56 !2e.*e.e~..m.~o*.e~e~ 7
92 Navy Air Propulsion Test Center T53-La-13A Engine
Data..... .... ees .*...Go ..666.0.........09....00..00 130
93oin n Navy rPooso Tests,,a Ce ter TY-L-11A to Engin
94 Comparison of T53-L-11A Emission Data Band From
Lycoming and Navy Tests .............. 133I
95 Comparison of T55-L-11 Avr Emission Data n FromLycomiAng and Navy Tests ata s *o o too.. *94~~ so .. 133,so
96 Comparison of T5-L-13A Average Emission Data From
Lycoming and Navy Tests .... t.a........o*.so.o....o.s.s.o 135
(IV
j;0A4 4*4o
Figure Page
98 Comparison of T53 Smoke Number Measurements FromLycoming and Navy Data ............... 137
99 Comparison of T55 Smoke Number Measurements FromLyconiing and Navy Data ........ too............. 00.... 137
100 T53 Laboratory Combustor, Fuel-Air Ratio and Effi-ciency Versus Traverse Angle atde....... 146
11 T53 Laboratory Combustor, ppm Emission Versus
Travers.e994Angle99at 147
12 T53 Laboratory Combustor, Emission Index VersusTraverse Angle at Idle..,... ... ... ~., to ..90 .*0t 6to40 148
103 T53 Laboratory Combustor, Fuel-Air Ratio andCombustion Efficiency Versus Traverse Angle at 30%oPower 9999999 . . ........... 1 49
104 T53 Laboratory Combustors ppm. Emissions VersusTraverse Angle at 30%6 Power.,...........**** **to# 1 50
105 T53 Laboratory Combustor, Emission Index VersusTraveraeAngle at3o Power......... . 151
106 T53 Laboratory Combustor, Fuel-Air Ratio andCombustion Efficiency Versus Traverse Angle at 6056Power.....*two..................***so..o..... 152
107 T53 Laboratory Combustors ppm Emissions VersusTraverse Angle at 6076 Power.. *seeso o...***so.t.o.9#. 153
108 T53 Labovatory Conibuetor, Emission Index VersusTraverse Angle at 6016 Power o s o o.o o so o o s o s, 154
109 T53 Laboratory Combustors Fuel-Air Ratio andCombustion Efficiency Versus Traverse Angle at 100%6Power...............SS.*4 ..00 ...06000.0*00646.0.9..040 155
110 T53 Laboratory Combustor, ppm Emissions VersusTraverse Angle at 100%o Power.... ose....,.... 156
ill T53 Laboratory Combustor. Emission Index VersusTraverse Angle at 100% Power................****s 157
Zvi
Figure Page_
112 T53 Engine Isopleth of CO (ppm) at Idle Power.. .. 1 59
113 T 53 Engine Isopleth of HC (ppmC) at Idle Power... 159
114 T 53 Engine Isopleth of NO (ppm) at Idle Pow...... 160
115 T53 Engine Isopleth of NOx (ppm) at Idle Power.... 160
116 T53 Engine [sopleth of Fuel-Air Ratio at Idle Power...* 161
-117 T 53 Engine Isopleth of Combustion Efficiency at Idle
t118 T53 Engine Isopleth of CO (ppm) at 3016 Power.. .. 162
119 T53 Engine Isopleth of HC (ppmC) at 30%6 Power...... 162
120 T53 Engine Isopleth of No (ppm) at 30%6 Power..... 163
121 T53 Engine Isopleth of NOx (ppm) at 30%6 Power....... 163
122 T53 Engine Isopleth of Fuel-Air Ratio at 30%o Power,,.. 164
t123 T53 Engine Isopleth of Combustion Efficiency at30% Power .............. ,.... 164
124 T53 Engine Isopleth of CO (ppmn) at 60% Power..... 165
125 T53 Engine Isopleth of HC (pprmC) at 60%6 Power *...165
. 126 T53 Engine Isopleth of NO(ppm) at 60oPowe..... 166
127 T53 Engine Isopleth of NOx (ppm) at 60%6 Powr....... 166
128 T 53 Engine Ioopleth of Fuel-Air Ratio at 60% Power... 167
129 T53 Engine Isopleth of Combustion Efficiency at60% Power *...o so .. ee *********a so*** *so so** ..... 167
[4 xvii
Figure Page
130 T53 Engine Isopleth of CO (ppm) at 100%6 Power..... 168
131 T53 Engine Isopleth of HC (ppnaC) at 100% Power ..... 168
132 T53 Engine Isopleth of NO (ppm) at 100% Power ....... 169
133 T53 Engine Isopleth of NOx (ppm) at 100%6 Power... 169}
134 T53 Engine Isopleth of Fuel-Air Ratio at 100%6 Power..* 170
135 T53 Engine Isopleth of Combustion Efficiency at 100%6
136 T55 Laboratory Combustor, Fuel-Air Ratio andCombustion Efficiency Versus Traverse Angle at
13? T55 Laboratory Combustor, ppm Emissions VersusTraverse Angle at Idle,.............. ... 174
138 T 55 Laboratory Combustor, Emission Index Versus
Traverse Angle at Idle,,,*....... .*s ****too. . .. *o** 175
139 T55 Laboratory Combuotor, Fuel-Air Ratio and
Combustion Efficiency Versus Traverse Angle at 30%
140 T55 Laboratory Combustor, ppm Emissions VersusTraverseAngle at3jo% Power,,... ass........e.. 177
141 T55 Laboratory Combustor, Emission Index VersusTraverse Angle at 30%o Power.*.. a, a...see........... s 178
142 T55 Laboratory Combustor, Fuel-A.Ar Ratio andCombustion Efficiency Versus Traverse Angle at 60%
143 T55 Laboratory Combutor, ppm Emissions -VersusTraverse Angle at 60% Power.o...............so* 180
144 T55 Laboratory Combustor, Emission Index VorsusTraverse Angle at 60%6 Power..,,,,*,,@* .. 0 00 0...... . 181
Xviii
Figure Page
L 145 T 55 Laboratory Combustor, Fuel-Air Ratio and18ComustonEffciecyVersus Traverse Angle at
146 T 55 Laboratory Combustor, ppm Emissions VersusTraverse Angle at 100%1o6 ..... .... ... 183
147 T55 Laboratory Comnbustor, Emission Index VersusTraverse Angle at 10016Power,........... 184
148 T55 Engine Isopleth of CO (ppm) at Idle Power. ... 186
149 T55 Engine 4'sopleth of HC (ppmC) at Idle Power .** 186t150 T55 Engine I~soplethof NO (ppm) at Idle Power,,,,***,, 187
151 T-55 Engine Isopleth of NO1 (ppm) at Idle Power.. . 187
152 T55 Engine Isopleth of Fuel-Air Ratio at Idle Power.... 188
153 T 55 Engine Isopleth of Combustion Efficiency at Idle
154 T55sEngine Isopleth ofCO (ppm) at 3076Power.... 189
155 TSS Engine Isopleth of HC (ppznC) at 30%6'Power.... 189
156 T55 Engine Isopleth of NO (ppm) at 3076Power..... oo 190
157 T55 Engine leopleth of NO1 (pprnat 30%6 Power ... 190
158 TS5 Engine Isopleth of Fuel-Air Ratio at 301o Power.... 191
159 T55 Engine luopleth of Combustion Efficiency at
160 TS5 Engine leopleth of HC 1ppmC) at 6076 Power***@**# 19%
161 T55 Engine leopleth of HC (ppmC) at 60%o Power Duringan Oil Seal Failure .................... 192
162 TS5 Engine leopleth of CO (ppm) at 60%o Power ......... 193
X '
Figure page
163 T55 Engine Isopleth of No (ppm) at 60% Power.. .** 193
164 T 55 Engine Isopleth of NO, (ppmf) at 60%06Power.... 194
165 T55 Engine Ispleth of Fuel-Air Ratio at 60%6 Power... 194
166 T55 Engine Isopleth-of Combustion Efficiency at
16? T 55 Engine Isopleth of CO (ppm) at 100% Po ...... 195
168 T 55 Engine Isopleth of NO (ppm) at 1 00%o Power.... * 196
169 T 55 Engine Isopleth of NOx (ppm). at 10076 Power.... 196
170 T55 Engine Isopleth of Fuel-Air Ratio at 100%6 Power..* 197
171 T55 Engine Isopleth of Combustion Efficiency at 100%/
Po e*/ et o * *o t. 99 es s o 9 9 9*oe o 9
xx
Table Pg
I EmisionMeasurements.Suirirary of Test Conditions.. 4
H a AayssDetector Lornponents . 30
III AerageCompositions and Properties of Fuels(C ) sed . . . . . . . . . . . .9 . . 4
IV OtmmadProbable Gas Sample Aaiysis Precision *57
V CmaioofFuel-Air Ratio Measurements FromVarious Sampling Configurations With ComnbustorRig Data . . . . . . . . . .. . . 66
VI Summary of Emissions From Lycoming T53-L-13Aand T55-L-llA Engines *.**.** * * *128
xxi
LIST OF SYMBOLS
a CO concentration term defined by Equation(2)
b hydrocarbon (CH/) concentration term defined byEquation(3)
C H single carbon fuel composition molecule used as typical ofunburned hydrocarbons
CO chemical symbol for carbon monoxide
CO 2 chemical symbol for carbon dioxide
F/A fuel-air mass ratio = W f/W
HC abbreviated chemical symbol for unburned hydrocarbonconstituents
m average number of hydrogen atoms per fuel molecule asdetermined by chemical analysis
n average number of carbon atoms per fuel molecule asdetermined by chemical analysis
NO chemical symbol for nitric oxide
NO chemical symbol for total nitric oxide components, usuallyx NO and NOz
THC total hydrocarbons measured by flame ionization detector(includes partially reacted and unreacted fuel components)
l bcombustion efficiencyr i actua l F/A
' 0 equivalence ratio - oc tui FAstoichiometric F/A
xxii
~INTRODUCTION
The control of exhaust gas emissions is a new requirement for aircraftpowerplants. Although these pollutants can be classed in various ways,those which have been identified as important for gas turbines arecarbon monoxide (CO), the nitric oxides (usually designated as NOx),and the unburned hydrocarbons (CnHn). To assess the total pollutantsproduced from an engine and aircraft system, data is needed over therange of engine operation from idle to maximum power. Total cyclicemissions for an engine in one aircraft may be quite different fronthe total in another aircraft using that same engine.
An item requiring consideration io the designation of the "idle" power.This is important because the total emissions of a helicopter over aspecified operational cycle are strongly a function of the time spentin a cycle at "idle". The "idle" power produces the largest quantityof unburned hydrocarbons (HC) and carbon monoxide (CO). In addition,"idle" power varies between aircraft, depending on the specificrequirements for the aircraft. Because emissions are a function ofthe engine power output, it follows that "idle" is not a precisely definedterm, but must be espicially specified for each engine in each aircraftinstallation.
Part of the problem of measurements is the taking of exhaust gassamples that are representative of the average exhaust gas composition.Measurements in the JT eD, reported in Reference 1, indicate thatlarge numbers of data points are required in order to obtain representa-tive sampling. Since these data were recorded for large fan engines,the obvious question is, do the same criteria apply to small turboshaftengines?
This report is concerned with exhaust gas emission measurements in.the Lycoming T3 and T55 gas turbine engines (Figures 1 and 2).
A single sample of exhaust emissions for the Lycoming T53-L-13Afand T55-L-IA engines has been moasured by the U.S. Naval Air
PropulsionTest Center. and is reported in References 2 and 3.- The testsdescribed in this report were of similar nature, but included additional
* - experimental and analytical evaluation, as discussed in the "Objectives"subsection.
OBJECTIVES
-'--m_ ,One of the principal objectives of the present w~ork was to test T53tand T55 combustors under laboratory test conditions, with controlled
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Figure 1. Lycoming T53-L-13A Engine Cutaway,Showing Combustor Arrangement.
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Figure 2. Lycoming T55-L-13A Engine Cutaway,Showing Combustor Arrangement.
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air inlet pressure and temperature, and then to compare the resultswith data from these same combustors in their respective engines.A second important objective was to sample the exhaust of both engineand combustor at 60 single points and with averaging (manifolded)sample probes. An analysis of these data will be used to evaluatethe effectiveness of the averaging probe. A third objective was tocompare the emission measurement results with those obtained onthe same model engines at the Naval Air Propulsion Test Center(References Z and 3) and with results from other gas turbine enginesreported in Reference 4.
TEST APPROACH
The concept of evaluating emissions in the engines and combustorswas put into practice by:
1. Laboratory combustor tests under simulated engine operatingconditions, with "average" sampling from multiorificeprobes.
2. Laboratory combustor tests at the same engine-simulatedoperating conditions, during which time 60-point gas sampledata were recorded.
3. Engine tests at a specified range of operating conditions, with"average" samples recorded with a cruciform probe. Smoke
sampling was also recorded with an alternate cruciform probe.
4. Engine tests at specific operating conditions, during whichtime a single-point sampling probe was traversed to covera predesignated sampling pattern..
The data points tested are shown in Table I. Note that combustorinlet pressure for some high-power engine test conditions could notbe simulated in the laboratory tests. Therefore, temperature and
fuel-air ratio simulation was correct, but not inlet pressure.
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TABLE I -Continued
Actual Engine and Conmbustor Rig Test Conditions
T53-L-13A
Air Temp Air Press. Fuel Flow F/ATest (Psia) (lb /h r) Engine NJ % SHP
C dtin Engine Rig Engine Rig Engine Rig Combustor Speed % SHP
1 198 28.2 ISO .0123 583'4
{4 410 415 64.5 65 380 385 .0147 83 30 420
5 480 487 85.7 84 570 580 .0169 92 54 755
6 490 - 90.2 - 625 -. 0177 93.6 63 880
7 545 547 106 84 800 670 .0203 99.6 96 1340
Air Temp Air Press. Fuel Flow F/A
Test (or)1~.... j(Da) (lb/hr) Engine NJ % SHPCondition Engine Rig Engine Rig Engine Rig Combustor Speed %SHP
1 305 310 42.7 43 475 481 .0110 68 7 263
z 356 - 52.7 - 625 .0122 75 13 487
3 392 58.7 - 716 .0128 78 17 638
* '4 430 426 69 72 830 840 .0128 82.5- 27 1013
5 500 498 91 8z 1320 1170 .0166 90.8 56 2100
6 526 99.7 1545 . .0183 93.0 70 2630
7 557 563 113.7 82 3960 1372 .0209 96.5 93 3490
Note: Operational and flight idle for the T51 is atCondition 2. Operational idle for the TIS isat Condition 4, approximately.
d/
EXPECTED RESULTS
It was expected that several types of information could be obtainedfrom the laboratory and engine tests:
1. The emission levels of each combustor independent of theengine
2. The emission level of the combustor installed in the engine
3. A comparison of the combustor laboratory and engine testresults
4. Calculations of combustion efficiency for both engine andlaboratory combustor
5. Determination of emission profiles, and a correlation betweenthe combustor and the engine and between various probeposition samples and the averaging probe
6. A comparison of the data with results from previous tests(References Z and 3) and with other engine data (Reference 4)
7. A measure of any change in oil leakage from bearing sealsby monitoring hydrocarbons in the engine exhaust
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DESCRIPTION OF TEST EQUIPMENT
LABORATORY COMBUSTOR EQUIPMENT
The laboratory test equipment was installed in the Lycoming Building19 complex, shown in Figure 3. A T55 compressor was used toproduce airflow for the lower power conditions. A combination oftwo T55 compressors was used for pressure to simulate the higherpower conditions. The compressor control panel is shown in Figure4. As noted on Table I, pressure was not available for the peakpower conditions, but fuel-air ratio and air temperature were correctlysimulated.
The combustors for both the T53-L-13A and the T55-L-11A engineswere production configurations used with these engines and containedno special modifications for these tests.
The combustor laboratory test rig for the T53 combustor consistedof the combustor liner, the engine housing, and the engine fuelmanifold assembly. These parts were installed in the test wayducting with inlet and exhaust transition sections, as shown inFigure 5. Interior thermocouples and gas sampling, with the 360-degreerotating actuator mechanism, are shown in Figures 6 through 8.
The arrangement of the probes in the annular exhaust is shown inFigure 9.
The T55 combustor test rig installed in the same test way is shownin Figure 10. This rig also consisted of a combustor liner, enginehousing, and engine fuel manifold assembly, all installed with inletand exhaust transition sections. Interior fixed probes are shown in Figure11. The 360-degree rotating thermocouples and gas sampling probeinstallation are shown in Figure 1 2. The dimensional arrangementof the probes is shown in Figure 13.
The 360-degree rotating drum assembly containing the five thermo-couples and the gas sampling probe was installed in the plane of the firstturbine nozzle inlet for both T53 and T55 combustors. The fivethermocouples were installed at different radii, so that, when the ,-i ... /
probe is rotated, a radial profile can be measured around thecombustor exhaust annulus (Figures 9 and 13).
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i. : Figure 5. T53 Laboratory Comnbuautor t".*t Rig in Teat Way 1.
: nn m unm m n npunm n a m in uu Imm m lu I • m um m m n n n w mmam nn u n n 9u
Figure 6. T53 Comnbustor Teat Rig, Curl and R~otatingDrum Assembly, Showing Thermocouple Leadsand Flexible Gas Sampling Lines.
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Figure lZ. T53 Comnbustor Test Big Curl and RotatingDrum Assemnbly, Showing Thermocoaplesand Flexible Gas Sampling Lines.
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Additional instrumentation in the combustor rig measured combustor
inlet air pressure and temperature, and exhaust pressure.
The 360-degree rotating mechanism five-port gas sampling probes for
the T53 and T55 combustors were water-cooled (Figures 14 and 15).
Water-cooling was specified because of the possibility of probe damagein the hot gases and to better ensure that the chemical reactions inthe gases would be quenched on entering the probe. A coiled-tubemethod was used to allow the probe to be rotated without damaging
the sampling line (Figures 6, 7, and 12).
The four fixed gas-sampling probes used in the T53 combustor testare shown in Figure 16. They were uncooled and were spaced asshown in Figure 9. They consist of five-port sampling which averagesthe gas sample at one circumferential position. The four probes weremanifolded together.
Mounted near the T55 rig traversing probe were four fixed five-portaveraging-type probes, water-cooled (Figure 17). The outlets ofthese probes were manifolded together for zone averaging. As seenin Figure 13, the probes are installed in the lower half of the combus-tor exit and are sloped slightly downward. Thus, if any fuel or watercondensation occurs in the water-cooled section, it will run "downhill"until it reaches the heated section of the sample lino. At this point,the temperature is high enough that the liquids will revaporize.
Gas samples are passed from the probe to an electrically heated"Dekoron" 3/8-inch stainless steel tube for transport to the detectorconsole, DS-16A (Figures 4 and 18). An electric controller regulatesthe tube temperature at approximately 3000 +10 0 F. A pressure dropacross the sampling probe inlet wat, designed into the system toobtain an equal flow into each of the probe sampling ports.
Other instrum -.ta included temperature and pressure measurementsto determino airflow and monitor the test rig, plus fuel meters.All measurements, except the gas analysis, were recorded on theDS-5 data system on punched tape (Figure 19). Tape was laterconverted to punched cards, and complete calculations were madeon the central computer system (IBM 370/155).
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Figure 14. Water-Cooled Rotating Gas SamplingProbe for T53 Combustor Test.
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Figure 16. Fixed-Position Gas Sampling Probes(TUncooled) for T53 Combustor.
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Figu~re 1?. Water-Cooled Fixed Gas Sam, plia- Probefor T55 Com~bustor -Test.
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Figure 19. DS-5 Combustor Performance DigitalData Acquisition and Control System.
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ENGINE TEST EQUIPMENT
To conduct exhaust gas analysis tests on T53-L-13A and T55-L-IIAengines, an outdoor, mobile test stand was used in close proximityto the gas analysis equipment. The test stand with the necessarytest equipment is shown in position in Figures 20 and 21. Controlof the engine was maintained from the control room on the trailer.Further details of the installation are discussed in Reference 5.
Engine Instrumentation
For both the T53-L-13A and T55-L-11A engines, power was absorbed
by a Lycoming water brake (Figures 20 and 21). A strain-gaged torqueelement mounted between the water brake and the engine inlet housingwas used to measure output shaft torque in both instances.
Engine airflow was measured with a calibrated inlet bellmouth setconsisting of an inner and outer bellmouth providing an inlet areaof 95. 16 square inches for the T53 and 141. 20 square inches for theT55 engine. Static and total pressures in the bellmouth were usedto determine referred engine airflow.
Compressor speed was measured by a Hewlett-Packard digital counter(Model No. 5214L), and power turbine speed was measured by aStandard Electric Time Tachometer (Model No. SG-6).
Fuel and oil flows were measured by the use of Cox turbine elementsin conjunction with a Hewlett-Packard digital counter (Model No.5214L).
Hydraulic and pneumatic pressures were measured by calibratedpressure gages.
Temperatures were measured with thermocouples in conjunctionwith self-balancing potentiometers.
Engine Exhaust Gas Measurements Equipment
Exhaust gas samples were acquired by both fixed and traversing 4
probes positioned in the exhaust gas stream. The gas samples werefed directly to the analysis equipment in the control room throughlines between the test stand and the building (Figure 3). The fixed
20
Figure Z0. Intake End of T53-L-13A Engine Mounteclon Portable Test Stand, Showing Water
Brake and Control Roomn.
Figure. Z1. T55 Engine Installed on Portable Test Stand,Showing Inlet and Wator Brake. (Power'Supply Trailer Is in the Background.)
probe design for the T53 and T55 engines is shown in Figure 22.The dimensions of the tubes and sampling ports were based on asimilar design used at the Naval Air Propulsion Test Center (References2 and 3. A second cruciform probe was installed in tandemapproximately 3 inches downstream of the gas sampler and atan angle of 45 degrees to it for taking smoke samples. Thedesign dimensions for this probe are also shown in Figure 22.
A photograph of the T55 fixed probe is shown in Figure 23. Installa-tion of this probe in the engine is shown in Figure 24, and the installa-tion of a similar probe in the T53 engine is shown in Figure 25.
A second probe with actuator (Figure Z6 and 27) was used in the engineexhaust to measure gas composition over a multipoint zone (Figure
28) during steady-state operation. This probe was designed inaccordance with SAE-ARP 1179 specifications for smoke sampling
(Reference 6). The probe position (angle and diameter location) wascontrolled from the engine trailer control room. T7,e probe withactuator is shown installed in the T55 engine in Figure 27. The probeactuator installed in the T53 engine is shown in Figure 25,
A pattern for single-point gas analysis was developed to provide alarge variety of data with a limitation of 60 sample points (Figure28). The center point was added. The criteria for this pattern were:
1. Radial point location on "equal area" lines
2. Sufficient points for obtaining several diametric profiles
3. Circumferential points for a centroid travei.e
4. In-between points for determining area concentration profiles
GAS ANALYSIS EQUIPMENT
The Lycoming on-line exhaust gas analysis system consists ofdetectors for measuring 0 , CO, CO 2 . HC, and NO. In addition,an NO analyzer was addel'to this system. The oxygen analyzerwas not used in these tests. The system schematically shown in
22
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Figure 23 Dual Exhauat Averaging Gas Sampling Probe f orT55 Engine.
24
Figue 24 T5 Engne n Tet Sand ithAvergin
Gas amplng robein Pace
Fig~re 25. T5 EngineIntl on ral Test Stand Wt vrgn
With AveragingDual Gas Sampling Probe.
(Actuator for Trawiruiag Probe Is in Place.)
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*Figure 26. Single-Point Gas Sampling Probe Used WithTraversing Mechanism for T53 and T55Exhaust Sampling.
Figure 27. Single-Point Exhaust Gas Sampling Probe
Installed on Actuator in T55 Engine Exhaust.
26
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Figure 28. Location of Gas Sai&Plng Points for T53 and T55 Engine*Exhaust.
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Figure 29 (Reference 7), consists of the following:
1. A high-speed pumping system to transport the sample fromtest rig to analyzer
Z. A "hot" sampling leg for HC analysis, in order to preventwater and HC condensation
3. A "cold" sampling leg for the CO 2 , CO, NO, and NOanalyze rs
4. Calibration valving for a wide range of gas compositionsand ranges of measurement
Data are recorded both on strip chart recorders and on punched tape.The punched tape data are converted to cards, and these are used ina program to calculate all desirable paramctei*& and plot some ofthe data.
Specific instruments in the system, their ranges, accuracy, andresponse time are listed in Table IM In addition, a TECO chemi-luninescance NO-NO analyzer was used for two tests to checkthe various NO-NO -NO values.
A heated sample transport system is contained in the LycomingBuilding 19 complex such that any test way can be connected to thegas analyzer cotsole in a few minutes. Thus,onR detector systemcan be used for several test rigs without moving it. The samplelines are made of 3/8-inch stainless steel tubing, electricalllheated, and insulated with layers of fiberglass and asbestos wool.A controller is installed for 60 feet t r less of heated sample line.
0Temperature control is set at about 300 F. A 60-foot heatedextension section was run from test way 12 to the outdoor tra..sportableengine test stand in order to connect to the gas analyzer console.
The velocity of gas in the sampling line was calculated to be 50 to 75ft/sec under conditions of atmospheric inlet pressure, such as wouldbe found with engine exhaust sampling. For thia calculation, a12-point sampling probe was used as shown in Figure 22. Samplepressure drop to the gas analysis console in this calculation wasassumed to be 5 psi, which was the normal operating condition.The method of calculation included Fanno line calculations ofcompressible gas friction pressure drop in a . 25-in. ID tube 150
28
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TABLE II, GAS ANALYSIS DETECTOR COMPONENTS
Full-Scale ResponseGas Model Ranges Accuracy* Time*
Nitric Oxide AMSA- ZOOS 0 -300U ppm +1% 90% in 5 sec(NO) Infrared detector 0- 1500 ppm
Carbon Monoxide MSA- 200 Tube No. 1 +1% 90% in 5 sec
Dual tube inf ra red 0-200 ppmdetector 0-800
-'I 0-3200Tube No. 2 +1%0-5%
Carbon Dioxide MSA- 300 0-856 +1% 90% in 5 se::Infrared detector 0-40%
Oxygen Beckman 715 0-5% +1% 90% in 20secPolarographicdete~ctor ~ 0-25% (at constant
tempe rature)
Hydrocarbons Varianj 400 0- 100 ppm +2% ApproximatelyFlame i r zat.,)n to approx. in low range 90%.in 10 secdetector'- 0- 20, 000 pprm +1% in high
range
Nitrogen Oxides EnviroMetrics 0.50 Ppm +2% 90% in 5 to 10 sec(NO) NS-200 to
x 0- 10, 000 ppm
*Per manufacturer's specifications
30
A j
feet long, with temperature held at 300°F (Reference 35).
SMOKE ANALYZER EQUIPMENT
The Lycoming smoke analyzer was designed to conform to SAE-ARP1179 (Reference 6). It is shown in Figures 30 and 31. The analyzerconsists of a pumping system which pulls a sample through heatedlines, meters the flow, and passes the gas through a standardizedfilter paper. The sample lines are heated to prevent water condensation.The reflectance of the smoke deposit on the filter paper is measuredwith a McBeth model RD-400 reflection densitometer. ARP 1179
~procedures are followed to determine the AIA smoke number.The system was pressure-checked before each test to ensure that the
sample lines did not leak.
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31
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HEATED LINE
(120 -1600F)
HEATED FILTER BT.OCK
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WHATMAN #4FILTER PAPER
ROTAMLTER
- SHUTOFF VALVEIFOR LEAK CHECKS
THROTTLE VALVE
VOLUMECOTLMETER
VACUUM PMGAUGE TEMP,
IN4DICATOR
Figuire 30. Schematic of the Lycomnig Stvitied Filter Paper SmokeAnlalyzer.
32
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33
PROCEDURES
EXHAUST GAS ANALYSIS CHEMISTRY
* I The chemical reaction for a typical hydrocarbon fuel that is notcompletely reacted is assumned to be as follows (Reference 7):
nCaHM +(0 2 + 3.73 N 2+ .04A) (n +m/4)--
nO [(- a -b) CO +aCO +bCH,1+ 0(m/) (1 b) H 0
[( L+ m/4) - 0 (a[1 -a/Z -b] + [m.I4] [l-b] )30+ [.04A +3.73 N] (n +m/4) (1)
where
aO co+C (2)C2 +rOnC /n
b Co H+CQ+C (3)C2 +rOnC /n
and CO, CO02, and CH M are measured volume fractions on a drybasis. m
The hydrocarbon product, CH min is used because the flame ionizationdetector measures effective cabon atoms.
It is assumed that unburned hydrocarbons remain as a combination ofC-H atoms, and that the only other unburned component is CO. Smokeor carbon particles are not considered. Hydrogen is present in suchsmall quantities at high combu&etion efficiency levels that its effecton combustion efficiency is assum~ed to be negligible (R~eference 8).
The hydrocarbon component (CH n11 1 ) is actually measured withina heated gas stream in order to prevent condensation of hydrocarbons;hence the gas is not dried, and the mitasurement is on a "wet" basis.For a typical engine luel rate at 2 5, the equilibrium water vaporis about 3. 5 percent. Therefore, the maximum, error by considering
34
£ Hm/n to be "dry" is about 3. 5 percent. For a typical 10 ppmC at
a high power point, 3. 5 percent error is negligible. For a typical100 ppmC at a low power point (F/A = 01), the possible error is1 percent, also negligible. The effect on calculated equivalenceratio is negligible.
Point equivalence ratio can then be calculated from Equation (1) froma knowledge of the CO, CO., and unburned hydrocarbons (CH /non a dry basis:
4. 77 (1 + m/4n) (4)1/(CO + CO + CHrn/n - a/Z - b (1 + m/4n)+ m/4n
The stoichiometric F/A for any hydrocarbon fuel may be calcu-lated from Equation (1):
(F/A) 2 (W /W)stoich. f a stoich.
(12) n + m- (n + m/4)(32 + 3.73 x 28 +.04 x 40) (5)
where
approximate molecular weights of C, 0 , N and A are 12, 32,28, and 40, respectively. For a JP-4 uel used at Lycoming(Table IV), n = 7.24; m = 14.07; and (F/A) can be calculatedto be 0.0679. For the JP-4R (referee grace) ue used in thesetests, with 15 percent aromatics, (F/) .... is 0.0692, anappreciable difference. The atomic proporCons of hydrogen andcarbon are average values from an analysis of the fuel. The F/Acan then be calculated from equivalence ratio:
F/A = (F/A)tih 0 (6)
Combustion efficiency for fuel can be determined Jrom equivalenceratio and a measure of the total unburned components, CO and CHThis equation is valid for all lean mixtures and rich mixtures at r/nlow values of 'A b where some oxygen is still unused:
CHM/n A H (fuel /C a w
%b fuel W f /(W + Wf()
35
where
rn/nMass concentration of unburned fuel in the exhaustw +wf
a f gas
'AH(CO)
t AH(fuel)]- CO. Mass CO equivalent to heating value of fuelL W + W
a +W in the exhaust gas
Wf/(Wa + Wf) = Total fuel/gas ratio = 1/(W a/Wf + 1)
For the fuels used in these tests, a mean value of A H (CO)AH. (fuel)
4,343= 2318, 702
For best results, a fuel heating value determination should be madefor the specific fuel used.
Carbon (n) and hydrogen (m) content and molecular weights are shownin Table I for a group of gas turbine fuels used at Lycoming.
For the data reduction used in the work reported here, Equation(4)was used to calculate equivalence ratio, Equations (5)and(6)to calculateF/A, atid Equation(7)to calculate combustion efficiency. A chemicalanalysis was made of typical fuel samples to determine mean molecularweight and C-H ratio. Bomb calorimeter heat of combustion measure-ments were made to determine the fuel lower heating value used inEquation (7). The heat of combustion of CO was obtained fromReference 9.
CALCULATION PROGRAMS
Calculation programs were available for:
1. Laboratory combustor rig data, where data input into theDS-5 data system are converted to pressures, temperatures,fuel flow, and airflow. Also, temperature traverse datawere programmed so that a plot of temperature profile canbe made (Reference 10).
36
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2. Engine data, where data recorded from instruments duringthe test are used to calculate fuel flow, airflow, and otherengine parameters (Reference 11). Inlet bellmouth airflowwas measured, and bleed flows were calculated to determinecombustor airflow.
3. Gas analysis data, where instrument calibration and output
signals are converted to ppm, lb/1000 lb fuel, F/A, andcombustion efficiency (Reference 12). In addition, emissiontraverses were plotted with the "Calcomp" plotter.
CALIBRATION OF INSTRUMENTATION
Laboratory Instruments
All laboratory instrumentation outputs were fed to the DS-5 data systemdescribed in Reference 13. This system contains calibration standards.The calibration method complies with MIL-C-4566ZA (Reference 14).
Engine Test Instrument Calibrations
Instrumentation used to measure the engine perfoirmance was calibratedper "Measurements and Test Equipment Calibration Systems" standard(Reference 15). This standard operating procedure for instrumentcalibrations was also written to conform to MIL-45662-A (Reference14).
Gas Analyzer Calibration
The Lycoming gas analyzer system is comprised of the detectorslisted in Table II. Calibration curves were supplied by the manufac-turer for the infrared analyzers (CO, CO 2, and NO). In this case,an initial check was made with various gas bottle calibration compo-sitions as a check on the manufacturer's calibration curve. Thechecks were within the combined instrument accuracy and theguaranteed (2%) accuracy of the calibration gas sample. For eachtest, a calibration gas was used to set the electrical output for eachinstrument at a range convenient to read on the chart recorder.
The flame ionization detector (FID), used to measure total hydro-carbons, was calibrated on two ranges, a factor of 10 apart. Thecalibration curve of this instrument appears linear. Data in roportsfrom the manufacturer also show linearity (Reference 16).
N 37
Jb
{Y
rBecause the FID flow quantity is a function of temperature and:;pressure at the metering orifice, it was deemed appropriate tocontrol these two factors. Temperature was controlled by a veryprecise oven temperature control inside the instrument casethrough which the gas passed. Pressure was controlled by anexterior located precision "Wintec" back pressure regulatbr. Inaddition, the pressure was recorded to within 0. 1 inch of water,and a calibration curve was made of pressure versus percent of"standard" reading (Figure 32). This correction was put into the
computer program so that any pressure deviation from the standardvalue was compensated in the data calculations. The instrumentoperating standard pressure was set at 30 inches of water gage.
The polarographic NO detector was operated with an activatedcharcoal absorber in tie sample train to absorb aldehydes, becausethe instrument is sensitive to aldehydes. However, the charcoalmay also absorb some NO. Therefore, the calibration gas wasset up to pass through the charcoal. It was assumed that the same
fraction of NO is absorbed in the charcoal as during a test, so thatthe charcoal absorption of NO is effectively cancelled out. Mostof the measurements were made in the range of 0 to 100 ppm, and thecalibration gas was normally approximately 60 ppm. Linearity inthis range was assumed.
A chemiluminescence analyzer (NO and NOx) was used on one test asa check on the infrared and polarographic instruments. It wascalibrated by using the same sample bottle mixture of NO and Nthat was used on the other NO and NO instruments. The manuactur-er (Thermal Electron Corporation) mlntains that this instrumentresponse is linear, and aur tests did not indicate otherwise.
The calibration procedures recommended in ARP-1256 (Reference 17)
were followed as closely as practicable.
Typical calibration curves are shown in Figure 33 for CO , inFigure 34 for NO (infrared) and hydrocarbons, in Figure *5 for CO,and in Figure 36 for NOX (polarographic). Electrical noise levelsare within the manufacturer's specifications.
38
mI I
1.40-
a-
PRSSR N 0.20
igue3.HdoabnClbainCreto atrVru
PrsuefrFaeInzto0eetr
I-9
fill.03% C02
Figure 33. Typical Calibration Trace for NDIR CO 2Analyze r.
000- ENVINOUETRICB
NC - VARIAN MCL 140
ATTIViUAIW 0
ATT IAIONi 10
NYSOCARUCN CAL
61101CALawAIWUNiAO
Figure 34. Typical Calibrations, NDIR NO Analyzer -
Hydrocarbon 111).
40
t6P
U
bo
E4 (2
II
COMBUSTOR TEST PROCEDURES
The combustor assembly, arbitrarily selected for both the T53-L-13Aand T55-L-llA engine, could be tested in both an engine and thelaboratory test rig. The test conditions included a specified idlepower point, 30, 60, and 100 percent (Reference 18). Sixty-pointtraverses were run at idle, 30, 60, and 100 percent power (Table I).A sixty-first point was recorded as a check on the first point.
The conditions to simulate engire operation were taken from engine
measurements and cycle calculations. The 100 percent power simula-tion pressure could not be met; therefore, the test was run at enginecycle specified temperature and F/A but not the specifiedpressure. The attainment of design pressure for the 60 percentpower point for the T55 was also found to be marginal and wasrun at the highest attainable pressure, as shown in Table I.
The desired operating conditions of air pressure, airflow rate, airtemperature, and fuel flow were controlled and allowed to stabilizebefore test data were recorded. Precautions were taken to maintaintest conditions unchanged during the long single-point traverse.However, steady flow is only maintained in any system within somelimit of both precision of control and precision of de',ecting anychange. A check procedure was used to detect any appreciablechanges in operating conditions, including:
1. For each 10 single-point samplings, Ln average sample wastaken. Thus. if the overall conditions were changed, theaverage sample would show it.
2. For each 10 to 20 sample points, the gas analyzer wasrecalibrated.
3. Fuel-air ratio from the test rig data was used to checkagainst F/A from the average gas sample. Disagreementlarger than the expected experimental error would indicateeither a leak, an error in measurement, or a nonrepresen-tative sample.
42
X0
Traverse survey data points were recorded after moving the probeto the next position and allowing the sample line to purge. Whenthe compositions reached a steady level on the recorder, the datawere then electrically recorded and punched into the tape. Averagetime per data point was Z minutes during traversing. Additionaltime was required for switching to the averaging probe, for recordingthe data, and for calibrating periodically.
At each point where the averaging probe was sampled, a thermo-couple temperature profile traverse was also recorded in the combul-tor exit. These temperature data were used for comparison with exitprofiles calculated from gas sampling, such as F/A. Adiabaticflame temperature can also be calculated from F/A and combus-tion efficiency (determined from gas analysis); however, this informa-tion was not considered to be needed for the analysis.
ENGINE TEST PROCEDURES
Initial engine tests were made for calibration purposes and to checkout the installation: Rnd eauipment.
For power performance tests, the engine was operated fromthe specified idle condition, increasing the power in steps up to fullpower, then back down to idle. '.:his was repeated. Approximately5 minutes was required to stabilize the engine operation at each powerlevel before recording data. Both gas sampL. s and smoke sampleswere recorded simultaneously on the double cruciform probe (Figure22), as shown on Table 1.
Gas samples were recorded when composition was observed tostabilize on the chart recorders. The punched tape system was used.Stable composition level was the signal to record the data. Two tofour minutes were required per data point to move the probe, purgethe lines, and obtain a stabilized reading. Calibration checks wererecorded normally after 20 data points. The whole T53 traverse wasdone with one setting of the actuator position, Center points wererepeated as each diameter was traversed as a check of operatingstability; i. e,. to determine if there were substantial changes ingas analysis determined F/A or any gas component with respectto time.
43
"'" ...... . " " " ",: ' ' " .. .. ..... ' .... .. ' ' ° ' ' I
For th(. T55 engine, the exhaust traverse was performed in twohalves of 40 points each. The center points were repeated on eachdiameter traverse, as with the T53, to check on stability and continu-ity of the engine operation. Also, the centerline diameter traversewas repeated on the second half of the traverse as a check of anychange in operation from the first half.
DATA CALCULATION AND INITIAL DATA PLOTS
Laboratory test data were processed on an IBM 370/155 computer. Theoutput of these computations include all the test rig conditions andflows of fuel and air, temperature (thermocouple) traverse data and
plotted profiles, and gas analysis data, including F/A andcombustion efficiency.
Engine operating data were manually recorded and processed forcomputer input. Gas analysis data from the engine employedthe same system for readout and calcalation as in laboratory combus-
tor tests. Gas analysis profile dAta recorded in the engine exhaustwere manually plotted.
GAS ANALYSIS PROBLEMS
Two problems in obtaining accurate gas analysis data were possiblysignificant, and sufficient information was not immediately availableon them. These are the problems of (1) the required temperature of
gas sampling lines to prevent hydrocarbon condensation and foulingof the sampling lines and (2) reliability of measurement of NO
x
Hydrocarbon Condensation in Sampling Lines
Since we have been analyzing engine and cornbustor exhaust gases,
there has been the problem of how hot the sampling line has to be to
prevent unburned fuel condensation. The SAE-ARP-1256 (Reference
17) prescribes a sample line temperature of 302°F (150 0 C) as
satisfactory. However, the 10 percent distillation point of a typical
JP-4 fuel occurs at about 210 0 F and the 90 percent point at 410 0 F. For
JP-4R, the initial point is less than 200F and the 90 percent point is
between 3250 and 370 0F. Does this mean that 302'F in the sampling
44
line is completely unsatisfactory if there are appreciable quantities ofunburned fuel? What concentrations of fuel- can be tolerated withoutproblems? An analysis was made to find answers to these questions.
The factors influencing fuel condensation in the sampling lines are:
1. The molecular weight and vapor pressure of the heaviest
molecular components of the fuel
2. The combustion efficiency, which determines approximatelywhat fraction of raw and cracked fuel is present
3. The temperature of the sampling line
The mean molecular compositions of JP-4 and JP-4R fuels used atLycoming are shown in Table III. Buth higher and lower molecularweights are included in the average, but the exact range and concen-trations are both unknown and quite variable within each fuel specifica-tion. A detailed analysis of all the components of the fuel would becostly, and probably worthless, because of the wide tolerablecomposition variability for each Military Specification. The originalcrude oil and the refining processes would also affect the type andconcentration of the fuel components. Some indication of the rangeof component molecular weights was obtained at Lycoming throughuse of chromatographic analysis. The results of a JP-4 fuel analysisshow compoinents from C 5 to C1 5 which was the highest weightdetected (Figure 37)1
Vapor pressure data (Reference 9) for various pure hydrocarboncompounds were plotted to determine the range of concentrationsthat might be expected in a sampling line at various line temperatureswithout getting condensation (Figure 38). However, the vapor pressure_AWof mixtures is not the sum of vapor pressure of the components.Heavy molecules will reduce the vapor pressure of light molecules,and vice versa. In Figure 38, a range of possible saturatedhydrocarbon fuel components is plotted against vapor pressure.The components were chosen to cover a range of molecular weightsthat might be found in the fuels, as noted in Table III and analyzedon Figure 37. This plot shows that a heavy fuel, such as Navy
45
.... ...
L- 00 NN ** C
LA N tnt- L LAcn N '' N 000 C
4)0 oo N * .
* q
0
N N U) L f Ln
200 0 - 00--
0 - %Q F-4 N.
0 00 Co o N0 - C -
-- 0
0
.44
044- C. ~ 0 - 4
41 -~ l
46'
U-)I0L*N.LLV&8 OL 3NVUi
a)NJ.J.Y~
0~.L 8V
0
474~
....... ..
00
loc
'I0 N o50 0
TEMMIATUAN -'F
Figure 38. Vapor Pressure of Various Hydrocarbous Versus Tempera-ture and Concentration.
48
Ii
distillate, may produce condensation that is a problem in the samplinglines if the 400°F temperature cannot be held, or if raw fuel of theorder of . 005 to .010 F/A is present even at 400°F. This assumesthat some of the distillate components, are C2 6 or heavier. The com-position of JP-4R fuel contains fewer heavy molecules than Navydistillate, and has a high probability of remaining gaseous at 3000 F.
In addition, "chromatographic" effect may be present. This effectis caused by absorption of components onto the wall for short periodsas the sample moves down the sample line and is evidenced in theresults by a longer period of time being required to purge the sampleline than would normally be expected. This condition can beexperienced even though the sample line is hot enough to keep allcomponents in a vapor state, but does not present a serious problem.It only increases the time required to purge an old sample and obtainan equilibrium sampleat a new test condition.
From an inspection of Figure 38,. we find that:
1. Condensation of hydrocarbons smaller than C is not aproblem, even with a line temperature of 300W as longas the concentration is not above 5000 ppm at 300 0F, or130,000 pprn at 400°DF. Since the average carbon contentfor JP-4 or JP-4R is about 14, it would be expected thatthere should be few condensation problems with either JP-4or JP-4R at 300 0 F.
2. A 400 0 F, C ,6 can be vaporized to about 1300 ppm (or 33, 800ppmC). Thra would represent about 80 percent of the fuelat a total F/A of . 020 or about 20 percent combustionefficiency from hydrocarbons alone. (CO may add someadditional inefficiency. ) This concentration wotld never beencountered in an engine exhaust, but might be found in a
*primary zone. Therefure, it appears that the major componentso! a fuel even as heavy as Navy distillate would have a gocdchance to remain in a vapor state at 400°FO
The foregoing analysis was purposely general to include a wide rangeof fuel gas analysis problems. However, from the results we concludethat JP-4 fuels should not cause a gas sampling line problem if thesampling line and adjacent parts are held in the 3000 F range and ifthe combustion ef"iciency i reasonable (85 percent or higher).
49
Reliability of Measurements of NO
The nitrogen oxide emissions are of particular interest because ofthe gradual atmospheric conversion to NO 2 , which is aneye, nose,2and lung irritant. However, only the formation of NO can be justifiedfrom chemical kinetic considerations. The more important reactionsare those proposed by Zeldovich in 1946 4Reference 19):
SO+ N2 -NO+ N (8)
N+0 2 NO + O (9)
Other reactions proposed by Newhall and Starkman (1968) and Lavoie,et al (1970), include (Reference 19):
0H + N NO + H (10)
N 2 +0 2 -NzO+ O (1)
N2 + OH N 2 0+H (1)
N2O+O NO + NO (13)
N+O +M NO (14)
N + O+ M N2 0+M (15)
The Zeldovich mechanism is generally sufficient to account for NOformation under conditions present in spark ignition engines. Theentire set of equations can be itsed for NO prediction for any combus-tion process. The process is limited by the presence of 0 radical.The usual method of calculation is to assume equilibrium compositionof 0 radical before the NO formation becomes important. At anyrate, neither Reference 19 nor References 20-29 indicate anymechanism for the formation of NO in the combustion chamber.A chemical kineticist working on thA problem suggested that aninvestigation of some NO 2 formation possibilities revealed that ifO radical was present in relatively large quantities at 12000 to 1400 0 F,NO 2 could be formed. However, the chemical kinetic probability oflarge 0 concentrations is very low. Therefore, in view of the
50
available evidence, we cannot explain or justify measurable quantitiesof NO 2 formed in the combustor.
Nevertheless, the literature is replete with gas turbine exhaust datashowing appreciable or even large quantities of NO. Typical are
data from References 27 and 30. In Reference 30, we find that theNO ./NO ratio is as large as 40 percent in an engine test. Datafrom the U.S. Bureau of Mines (Reference 27) indicate largepercentages of NO 2 , but the actual value of NO is only in the range of
2 25 to 10 ppm. Analysis of NO and NO data from Reference 42shows that there is a wide range of variation of NO measurements.
Contrarywise, the NO data all point in the same direction, but notthe NO 2 . The conclusion reached is that NO 2 can vary between5 and 20 ppm, and is sometimes a little more, and that it isalmost independent of engine configuration or percent power.
The presence of this NO 2 (not theoretically explainable) is a topic forinvestigation, but not the principal purpose of this report. However,some evidence suggests that the sample probing system may permitconversion of NO to NO 2 .
Thus, it is possible that the only reason for measuring NOx or NO,in addition to NO, is that some of the NO may have converted to N6 2between combustor and detector. Of course, the total of NOand NO is the toxic pollutant of interest. We can see that ifthe exhaust gas could be analyzed without any "en route" conversionto NO 2 , the analysis of NO only should be quite satisfactoryfrom available knowledge of chemical kinetics. So it is only tomake sure that we know this converted quality, that NO 2 orNO measurement is needed.
x
The next problem we encounter in our measurement of NO X is theprecision of the measurement. Presently, the methods used forNO measurement are:
1. Polarographic for NOx
2. Nondisperaive infrared (NDIR) for NO
3. Nondiupersive ultraviolet (NDUV) for NO (not used in thesetests)
X
4. Chemiluminescence for NO and NO X
51
Good comparison of NDIR, chemiluminescence and polarographicmethods was obtained by Shaw in Reference 31, where he reportsagreement within 5 percent, In the present work, agreement waswithin 10 percent for NO measurement, and within 10 to 15 percentfor most NO measurements. Chase* reports less than 1 percent
xdifference between chemiluminescence and NDIR and nondisper-sive ultraviolet (NDUV), when calibrated carefully and knowncorrections are applied. He used special processing to obtainNO gas without NO contamination, and N zero gas without NO.
2 N2
The initial problem in NO measurement precision is the calibrationxgas itself. Calibration gases can be purchased with a 1 or Z percent"guaranteed" accuracy. Information from vendors indicates thatat least two methods of filling the bottle and analyzing it are used.In one case, the bottle is filled and analyzed quickly, and sent to thecustomer. In this case, some of the calibration gas (NO) mayabsorb into the bottle walls over a time period. But, as the gas isused, the absorbed gas is released. The question of the compositionversus time is a moot one. In the other method, the gas is allowedto stay in the bottle for a period of time before the analysis is made.It is assumed that the gases are in equilibrium with the bottle atthe time of analysis, and normally will hold their composition untilthe bottle pressure becomes quite low. At this time, the absorbedgas re-emits. Calibrated gases for these tests were analyzed bythe second method.
Other problems are the deterioration of the sample in the bottle.Any traces of O will react with NO to form NO. The excellentagreement between three methods of measurement at the Bureauof Mines was obtained by careful mixing of calibration gases toremove 0 from the N and remove NO from the NO.
2 2 2
Storage at low temperature will cause striation of the gases, aresult of condensation or partial condensation of the heavier gasesin the bottle. This is characteristic of all mixed gas bottles, anda possible cause of poor reference calibrations.
Next are problems of measurement in the specific instruments.
*Chase, J. (U.S. Bur. Mines), CORRELATION OF NDIR, NDUV,AND CHEMILUMINESCENCE NO-NO x DETECTORS, PrivateCommunication, 10 December 1972.
52
Nondispersive Infrared (NDIR) for NO
The main problem with this instrument is its sensitivity to watervapor. The NO infrared absorption band is so close to the watervapor band, that two precautions are required:
1. A special narrow band-pass filter is used to reduce (but noteliminate) water vapor effects.
2. The sample must be thoroughly dried.
In the process of drying the sample, the efficiency of the dryingcompound enters into the picture. "Drierite" was used in thepresent work. There are disagreements among various investi-gators as to which driers are effective without absorbing themeasured component. The consensus appears about 50-50 for"-Drie rite".
Sensitivity of this instrument is obtained by using a longer opticalabsorption tube, which adds to the bulk and complexity of theinstrument.
Polarographic
This detector was capable of measuring either NO or NOR;however, only NO was measured. The problemsIound withxthe NO detector were:
x
1. Zero drift, probably caused by aldehyde interference. Thiswas nearly eliminated by using an activated charcoal filterin line with the detector. Because the charcoal absorbssome NO , the unit was calibrated with the charcoal in thesample lAe. It was then assumed that the percentage ofNO absorbed during calibration was the same as duringtenfng. It was also found that the duration of use oi the
.charcoal affected response. This effect was thought to hecaused by saturation of the charcoal.
2. Nonuniformity of response. The NO results appeared to bemore variable over a period of time tan the NDLR orchemiluminescence data.
53
"%/
., . . . . ..< , ": "o ./ .. . , :- ! /. . ........... . .. ... ..
- ' '- x i , ./.. , • . i< . , .. . . . . "/
-,... / . , , .' .. , . . ., . :
3. Carbon monoxide interference. This was checked and wasfound to be appreciable only when CO was present in largequantitites; i.e., percent concentrations, rather than ppm.
Chemilumine s cence
This detector was used on one test to check the NDIR and thepolarographic detectors. The detection of NO appeared stableand showed agreement with the NDIR and polarographic (NO)within about 10 percent. However, the NO values were allxlower than the NO values, a physical impossibility. Chaseindicated that this phenomenon is not unusual, and that it isassociated with the converter unit efficiency in the instrtunent.
SChemical equilibrium is established between NO and NO,I thus:
NO z =NO+O (16)
This reaction is sensitive to temperature and pressure, andthe percent of conversion calculated from chemical equilibriumagreed quite well with the measurements. Conclusions reachedon NO measurements are:
x
1. NO measurements with NDIR and chemiluminescenceinstruments are reliable and agree within 5 to 10 ppmnormally.
2. NO measurements are not as reliable because of possiblewater vapor absorption of NO 2 , inefficiency of thermalconverters, and interferences in polarographic detectors.
3. Calibration gases for NO, NO 2 , and zero references maybe contributors to measurement errors.
4. The principal concern in measurement of nitrogen oxidesis the total NO plus NO., or NO If NO formation can
be controlled to a negligible amount, then NO measurementonly is necessary. Otherwise, a reliable measurement ofNO is satisfactory. At present, NO measurements appearto e more reliable than NO or NO 2 measurements.
54
5. A solution is suggested in the use of a thermal converterwith all NO measurements. Its efficiency would bedeterrninedby calibration. NO would be the primarymeasurement. This procedure would be applicable forengine or combustor testing, and obviously, not applicableto atmospheric measurements. With this approach, anyformation of NO in the sample system would be of no concern.
I1-I,.I
I I5
DISCUSSION OF DATA AND RESULTS
ANALYSIS OF PRECISION OF THE MEASUREMENTS
Before discussing the test ;qults, an explanation of the precisionof our measurements is ."ustifihd in order to judge the valhe of theresults. Later, compar sons will be made with data from othersources as a further evaluation of our overall methods, procedures,and accuracy.
Precision of results can be divided as follows:
1. Measurement precision of the instruments only
2. Correlation of gas analysis measurement with fuel-aircalculations by other means (fuel and airflow measurements)
3. Effect of sampling probe position on the measured average
4. Effect of measurement precision on emission determination
5. Characteristics of tested angins compared with a statisticalgroup
Instrument Precision
Instrument precision specified by the manufacturers is shown inTable IV. The specifications here can be judged to be as close toreality as is possible if the instruments are carefully maintained,calibrated, and checked, and if calibration curves are correct.However, the accuracy propounded by the manufacturer cannot alwaysbe maintained. In one case, minor malfunction of the CO onalyzercaused error in the CO analysis that was not discovered until someobviously unreasonable data were recorded. After servicing, theunit operated satisfactorily. In another case, the CO Z calibi-ationcurve apparently shifted slightly. Data were recalculated afterdetermining a new calibration curve. The new calibration curve wasgene rated by plotting instrument response for several CO 2 calibrationgas concentrations. As a result of these experiences, it would seemmore reasonable to expect dependable accuracies of the order of±3 to 4 percent of full scale rather than I percent. In addition,the guaranteed acctiracy of the calibration botde is +2 percent.
56
TABLE IV. OPTIMUM AND PROBABLE GAS SAMPLEANALYSIS PRECISION
More
Manufacturer's ProbableSpecification Accuracy
ful Scale
Instrument Accuracy +1% +3/
Calibration Bottle Accuracy +1%* +2%
Total Full-Scale Accuracy ±2% +5%
At 30% of Full Scale
Instrument Accuracy +3% +10%
Calibration Bottle +0. 3%** + 1. 4%***
Total for 30% of Full Scale ±3.3% +11.4%
It is assumed here that no error is present from poor calibrationcurves.
* Calibration bottles are obtainable guaranteed for 1% accuracy.
** Assumes calibration gas for full-scale deflection.
*** Assumes calibration gas for 1 /2 of full scale, which is much morelikely to occur than when full-scale calibration gas is obtainable.
57
-/, 'i-
Considering that precision values are usually specified at full-scaledeflection, if the same variation is applied at 30 percent of fullscale (where readings are often made), then accuracy is furtheraffected (Table IV). These values of accuracy (Table IV) representa "best" and a "conservative" view of accuracy of gas analysis.Now let us look at the effect of these error quantities on the emissionmeasurements.
Correlation of F/A (Gas Analysis) with F/A (Measurements)
The correlation of F/A determined by gas analysis from the engineor test rig with F/A from the .el and air measurement tells us twothings: (1) whether the sample is representative of the average gascomposition, and (Z) whether there are leaks in the system whichwould dilute the sample. This F/A correlation is, of course, subjectto the accuracy of both the gas analysis and the engine or combustorfuel and air measurements.
In the laboratory combustor tests, fuel flow and airflow can be quiteprecisely measured with calibrated fuel flow meters and precision-made orifice plates for airflow. Calculations of the flows includetemperature corrections. Pressure and temperature instrumentsare calibrated at regular intervals. Estimated accuracy is +1percent for each measurement.
Engine F/A is also determined by measured fuel flow rite, andairflow measurement at a calibrated bellmouth at the engine inlet.The precision of this measurement is not quite as good as in thelaboratory test for these reasons:
1. At low power settings, the pressure drop at the bellmouthinlet is low, and accuracy suffers.
2. The precise quantity of air entering the combustor isdetermined from bellmouth measured airflow and fromcalculated engine cooling and internal airflow network.
3. Low-power interstage compressor bleed is reproduciblewithin +216 of the total airflow.
Considering all of the foregoing problems of calibration, accuracy,and precision, we then look at a comparison of the two completely
58
independent methods of F/A measurement: (1) gas analysis and(2) fuel and air metering. The comparison tells soniething aboutboth measurements, and also tells whether the gas analysis sampleis representative of the overall gas composition. F/A can be takenas a measure of just how representative are the emission concentrationsif we can assume that the gases are all mixed in the same proportion
and that there is no selective separation of exhaust gas components.These are thought to be reasonable assumptions.
Fuel-air correlation data for combustors and engine are plotted inFigures 39 through 41. Most of the data lie within the 10 percent
margin, and all of it well within the ARP-1256 specification of 15percent. The T53 engine "traverse average" data lie within 3 to 4percent. Some detailed explanations are:
1. Figure 39 shows the F/A correlation for the T53 and T55laboratory combustor measurements. Here the "idle" pointgas analysis for both T53 and T55 combustors seems to below, as does the maximum power T55 point. For the idlepoint, one possible explanation ia that a high concentration offuel exists near the wall at the measuring station causedby fuel vaporizing off the wall in the upstream end of thecombustor. As for the maximum power poin. in the T55
4 combustor, the explanation lies in damaged sampling probe.This probe is water-cooled (Figure 15) and contains fivesample ports across the height of the combustor exit annulus.At some point in the test, the water was turned off. Over-heating occurred at the peak of the temperature profile(2/3 of the channel height) where the F/A was maximum.Thus, the probe selectively sampled the leanest part of theflow and gave the low reading shown. The traversing probestaken from the T53 and T55 rigs after the completion oftesting are shown in Figure 42.
2. Figure 40 shows F/A correlation data for the T53 engine."Traverse average" data correlations are exceptionally close.The averaging probe correlations deviate as much as 10
59
, I
.025
A!T53 RIG
SQ T55 RIG /
.020 - /
015-*.J0
.010 .015 .020 .025
GASANALYSIS FUEL-AIRRATIO
Figure 39. Correlation of Rig Fuel-Air Ratio With Gas AnalysisFuel-Air Ratio for Laboratory T53 and T55 Comnbustor.
6
.065
/4.
iI II im i*mai i I I$ i i ii i i iN.li m li m
.025
A T53 TRAVERSE AVERAGE
0 T53 CRUCIFORM PROBE
~...020
4zw
1 .015
GAS ANALYSIS FUEL- AIR RATIO
Figure 40. Correlation of T53 Engine Fuel-Air Ratio With GasAnalysis Fuel-Air Ratio for T53 Engine.
61
.025 6 0
A T55 TRAVERSE AVERAGE
0 T55 CRUCIFORM PROBE / 4
4< .020
w< /z
w0
S .015 IL //
.010
.010 .015 .020 .025
GAS ANALYSIS FUEL AIR RATIO
Figure 41. Correlation of T55 Tngine 2'uel-Air Ratio With Gas Analysis
Fuel-Air Ratio.
6Z
IN,
dv,..-
444 - ~ iiE-1
Inn
4;
X. 4
' ~ ~ ~ ~ . 0'-4~Vt .
V.-" Y'-4
yJ4~~~
04~A' ,
941" V
U-4-l
4-Y4 N44-
4.44
4.4 .4 .44- .44
4 '. .....
44
-4 -
iMAR 444
14. .
A)4#-141 444'-4 4
'--.j~c- '-: --4 45- 4>4 4 - 44- v.4 4444441441 ;4 is-ttV4 A ,
- 44 *~,.. 444543 A ,4A4 4'i6 S445V2M 4A,4!# tVA 44 t44~t~hj44'H $.S~ f 4S4AA Kns "IN, $
'Al
63
...... .
percent. The larger deviations of the fixed probe are causedin part by (1) the probing location, which may not be asrepresentative as the "traverse average", and (2) the shorttime duration of the measurement, where reading errorscannot be "averaged out".
3. Figure 41 shows the T55 engine F/A correlations. Exceptfor one point, the "traverse average" correlations arewithin 2 to 3 percent. "Cruciform-probe average" dataproduce consistently high F/A values, with a 10 to 12 percentband scatter. These high values cannot be explained bythe shape of the exhaust concentration profile with respectto the location of points sampled by the cruciform probe.It is likely that the problem results from calibration proce-dure. Actual CO, concentrations for these points lie between
22. 6 and 4. 5 percent. The data with the largest differenceswere recorded with 1.6 percent CO calibration gas, whereasthe remaining data were recorded with 2. 5 percent calibra-tion gas. One "traverse average" point at high powerdeviated from the 1:1 line by 12 percent. This point repre-sents a 40-point (1/2) traverse performed at a later dateto fill in missing emissions data. Again, the use of a 1.6percent calibration gas is the probable cause of the greater-than-usual deviation.
The variation of concentrations was plotted versus time to provide agraphical illustration of engine variables during a steady-state operation(Figure 43). A method of compensation for this time variable wasused in order to compare concentration on a common or "normalized"basis. Variability may be caused by changes in ambient temperatureand pressure, small engine control variables, and characteristics ofthe operator, plus human interpretation of the readings.
Effect of Exhaust Duct Sampling Probe Position on Measured Average
The data taken in this program have provided detailed exhaust traversesfor two engines and two laboratory cormbustor rigs. From the 60-pointtraverses taken on each combustor or engine, we can select the typeof multiport probe to obtain an average dmission accuracy within aspecified percent. Probe sampling type and probe location, allaverages, are compared in Table V.
64
'4j
ata
al
k 1
44
4 65
0r. C.)
ri P ) 0 )
x 0 t
0£ 0
CE40l
Hd H HPH
0 0 0 00 0 0 0 Is 0 0
CA .0 ~
0 0 0 0 0 0
\j 4 -18~*~~
0 4
t~Lt,
66
The traverses in the engine exhaust duct provide both circum-
ferential and radial profiles. However, slight variation in the controlof the engine and ambient conditions causes shifts in measuredconcentrations. The changes in exhaust composition between traverseand cruciform probe tests make a direct comparison of the accuracyof the cruciform probe impractical. Even the variations observedduring the course of a single traverse indicate that some of thefluctuations are spatial and some are a function of time. The diametralprofiles show some random variations which may be more representa-tive of the time at which the point, was taken rather than the positionof the probe. At higher power levels, where emissions tend to besteadier, many of the profiles show a clear radial variation whichcorresponds to the hub to tip temperature profile built into thecombustor.
Effect of Precision on Emissions Measurement and Determination
The effect of gas analysis on F/A can be determined fromEquations 2, 3, and 4. The predominant effect is the CO concentra-tion, normally one of the most reliable measurements. irrors inF/A are nearly directly proportional to errors in the CO measure-ment*. The terms "a" and "b" are normally quite small, as is COand CHIn/n compared to CO 2 . By using an P pproximate value ofm/n 2 and setting a = b =, equivalencu r-' to (0) can be calculated:
0 *. 4.77 (1. 5)l/(CO+ COa + CH! n ) + 4n
or( , ,, 77 CO 2
07 7 00 /COz +0.5 1 +.5CO
It can be sen from this equation that a 10 percent error in CO., willhave an effect of about 10 percent on 0 and F/A. *
*Leak checks were made periodically during the tests by changing thesample line pressure. Any substantial change in concentrationswould indicate a change in leak rate, if a leak existed.
67
1
With the foregoing considerations of accuracy and precision, we mayconclude that ±10 percent is a conservative estimate of accuracy thatcan be expected for most cases, and with careful work. It is obviousthat much better precision than this is possible, and also that 10percent may be too low when measuring low concentrations. Anerror analysis is shown in Table IV. Here a small error is a largepercentage, and it may be asking too much of any instrument tomeasure reliably anything closer than +5 ppm for .O or HC and+5 to 10:ppm for NO. The principal question is, "How does this relative-ly easily obtained 10% precision affect the determination of emissionmeasurements ?" If we examine the objective of "measuring andreducing pollutants" in perspective, we find that the real objectivesare;
1. Determining the quantity of pollutants within a reasonableaccuracy
2. Reducing the pollutants by a large amount (Reference 33)
In view of the present EPA proposed requirement of reductions of theorder of 90 percent of some pollutants, the +10 percent in emissionmeasuring accuracy is judged to be "reasonable". It may also bepointed out that in measurements in the exhausts of many engines,as reported in Reference 4, the variations in measurements obtainedby different agencies on the same model engine are considerablygreater than 10 percent.
Therefore, the specification of EPA (Reference 33) that precision ofmeasuremient be set at +1 to 2 percent appears difficult, and maynot be necessary in order to meet measurement objectives. Thepercentages specified appear to be instr'4ment manufacturer's specifi-cations under ideal conditions, for full-scale deflection only, andfor calibration gases with zero error. A more realistic calibrationand precision determination should be established by setting standardsfor calibration and supplying known sample mixtures to users todetermine their instrument precision. The efforts of the NationalBureau of Standards, or other agencies, would be needed for this
procedure.
Comparison bf T53 and T55 Test Engine Performance With a StatisticalG rouu Performance
Because this program of emission testing of T53 and T55 engines was
68
V
limited to one engine only of each type, it was considered importantto analyze the performance of each engine and determine whether itwas typical of performance for that engine model.
Test engines used in the exhaust emissions program were chosen fromLycoming's "house engine" resources based on considerations of con-figuration and availability. A performance analysis was made to estab-lish these engines as representative of a group of engines by comparingtheir performance with production engine performance available froman extensive data bank. The data bank includes statistical treatmentof data to estimate sample population limits on various performanceparameters. This comparison is made to ensure that both rig and enginecombustor inlet parameters are representative of typical engine opera-tion, particularly as regards possible extraneous combustor bypassairflow caused by overboard leakage, or by nontypical internal coolingar.d/or seal pressurization flows.
T53-L-13 Engine K-1Z1J
Performance data from T5 3-L-13A engine K- l2 U taken duringinitial checkout and emission testing are shown in Figures 44 and45 for comparison with performance of over 7400 T53-I-13 engines."Time since new" (TSN) on this engine prior to test wrs approxi-mately 140 hours. The tolerance band shown is derived fromstatistical analysis of this engine population by utilizing computercurve fitting techniques and conventional data reduction practiceto normalize data to "standard day" conditions, Available data arelimited to the power levels required for production acceptance of theengine; io e., 75 percent normal rated power to military rated
/. power. The range of the date is sufficient to indicate the K- 12 UJis not untypical of T53 engine performance in the high power
(interstage bleed closed regime) with respect to level and slopeof the aerothermodynamic para meters. A review of the buildupI. records of the engine and visual examination of hardware, com-bined with the measured performance, support a conclusion thatengine internal airflows and leakage are within acceptable limits.
Data in the ground a.- f!tght idle regime from a sample of 15T53-L-13 engincs are shown in Figures 46 and 47 for cornparisonwith K"1213 performance: they indicate typical part-speed inter-stage bleed-opened operation. Flight idle operation is specified
69t69
SEA LEVEL, STrADARD DAY
1800-
A K 121J
I UU0 T53-L-13A MODEL SPECIFICATION
104.33 (SEPT 1968)- .~ - -AVERAGE ENGINE
.. 95% TOLERANCE LIMIT ON POPULATION
IZOC - . -~.00___10
1400--'
~101700
AA
1400 94-
1j300 /
g/oP1200
1000 //
Ila 60
g0o 1000 Iton 1200 I1100 1400 1500 92 94 $6 is 100 tog
611AV'1 UoS1ZCP0Wi - shp NJ
Figure 44. T53-L-13 Engine K-IZlJ Performance Comparison With7 400- Engin* Sample.
70
- AVERAGE ENGINE
:"O 95% TOLERANCE LIMITS ON POPULATION580560 "' " -- IA K 1211
560
H "520 - - 1900 . .
4, 0 100 0 1
1700gooo . 1 1
Booo do
|1 i 4 00
403.700
6000
10 1
7.5 1,0.0
A -
70
. # 11.0 - - -.
4.04
Figure 45.70E oT53"L13 Enginep K-121J Performance Comparison With
kt# 740 Enin Sapl
.11
llil/ 0.-- A
SEA LEVEL, STANDARD DAY
A K-121J
400
E-30
0
xHINW30
2000
100 __ _ _ _ _ _ _ _ _ _
E-I
3.0
M " 2.0
1.0
0
900
'Aa'
7006so60 70 80
PERCENT N11 %rj
Figxre46.T53L-1 Eni'~ j$12 13 Low Power PerformanceComparison With i5-Engine Sample,,
72-
SEA LEVEL, STANDARD DAY
A K-121J
300
~ 200 FUEL FLOW 4
S60
I6.
1* 5.04.0 _ _ _ _ _ _ _
200
10 A58% Nil SPEED
500
so 50 70 so
PEUCENT NI 01P 25,150 RN1
Figure 47. T53-L-13 Engine K-1211 Low Power PerformanceComparison With IS-Engine Sample.
73
at a maximum fuel flow of ZZ0 lb/hr, corresponding to a gasproducer speed of approximately 71 percent for engine K-1213.Power under this condition may vary from zero, at twice optimumfree power turbine speed (approximately 80 percent), to a maximumof approximately 1. 2 horsepower, when the power turbine is runningat optimum speed (approximately 40 percent). Based on inputfrom Lycoming's flight test and field service operations, theT53-L-13 engine, as used in the Bell UH-l aircraft, utilizes thepreceding "flight idle" setting as "operational idle" for groundrunning prior to lift-off. The relationship between free powertgrbine speed and output power, at constant gas generator speed,is shown in Figure 47, where optimum free turbine speed wasmaintained for the 15-engine sample.
T55-L-1lA Engine B-19Q
Data from T55-L-11A engine B-19Q are compared with T55-L-11production engine population limits in Figures 48 and 49, andindicate acceptable limits of performance, with all aerothermo-dynamic parameters within normal values. The engine hadacquired approximately 235 hours TSN. The T55-L-11A engineincorporates modifications to the hot-end; this resulted in minorchanges to the T55-L-11 model specification as indicated by theacceptance limits per MCR 2108, dated 21 September 197Z.
Low-speed, interstage bleed-open data from a sample of T55-L-11A engines (Figures 50 and 51), when compared with B-19Qperformance, indicate that bleed and turbine cooling airflowsare within acceptable limits. Flight idle operation is specified eta maximum fuel flow of 505 lb/hr for the T53-L-11A, which wouldcorrespond to a gas generator speed of approxinately 70 percentcompressor speed for engine B-19Q. Power turbine speed wasset close to optimun values for this test series, as can be seenin Figure 51.
"Operational idle" as applied to the Vertol CH-47C is set atapproximately 82 percent compressor speed (slightly above theinterstage bleed steady-state closure point). Data from B-19Qat this condition are shown in Figures 50 and 51. This compressorspeed meets the engine-airframe systems integration require-ments.
74
SEA LEVEL, STANDOARD D2AY
95% TOLERANCE LIMITS ON POPULATIONAVERAGE ENGINE
A B-190T55-L-11A ACCEPTANCE SPECIFICATION NCR 2108 (SEPT 1972)
8.0 - - -2200
200
2800 _ -- 4D n7.0 r.p
/ # ~1400 -
A -
~6.0 10
1000
~28 - -
3600
22
002001A Ii:: --=pp to- 100I 7 0
*100-~-*-0
- o .0 do I
100 ;- -00
454 2400 /~t0 92 94 96 Is too 90 92 94 94 is too 102
PNCMT NJ PBiN3IWU j -
Figzre 48. T55-L-1lA Engine B-190 Performance Comparison ~With 493-Enagine Sample.
75
I -
SEA LEVEL, STANDARD) DAY
951 TOLERANCE LIMITS ON POPULATION
-AVERAGE ENGXNFP
B -ISQ
0 TSS-L-11A ACCIIPTANCE SPECIFICATION NCR 2108 (SEPT 1972)
S1800
1600
1600
1500
too0 as" 1000 3100 4000
so"
Figure 49. T55-L-11A Engine B-19Q Performance ComparisonWith 493-Engine Sample.
76
SEA LEVEL, STANDARD DAY
AB-19Q 440 AB-190 BLEED CLOSED (OPERATIONAL IDLE CH47C)
E-4t
11300 ______________
14 200
20
10
5.0
0
4.0
3.0
0
1.0155 65 75 85
PERCENT NjI
Figure 50. T55-L-1lA Engine B-19A Performance ComparisonWith 5-Engine Sample.
"N 77
SEA LEVEL, STANDARD DAY
A B-19QAB-19Q BLEED CLOSED (OPERATIONAL IDLE CH47C)
800
600
o400
1000
'p1 900 A__ _ _ _
or...AO
700
1000
55 65 75 85
PERCENT N1 OF 18 720 RPM
Figure 51. T55-L-11A Engine B-19A Performanice CompartnonWith 5-Engine Sample.
78
Conclusion
Both engines selected for these emission tests meet their specificperformance requirements. "Operational idle" used in the aircraftapplication should be the idle used for reporting emissions. Thepower used to describe this condition should be assumed to be opti-
mum Nil rather than the measured power resulting from real NIused in the aircraft. Combustor operating conlitions are the samein both cases.
TEST RESULTS
The data will be discussed in groupings to better correlate the results,in this order Zor each engine:
1. Combustor resultsZ. Engine results3. A comparison of combustor and engine data
4. Comparison of Lycoming and Navy data5. Other comparisons
T53 Combustor Results
The combustor tests were performed to simulate engine operating con-ditions as closely as possible, but, obviously, there are limitations.Known differences between engine and laboratory combustor operationare:
1. Turbulence level and velocity profiles that enter the combustorfrom the compressor
2. Pressure level in cases where combustor pressure was notexactly duplicated
3. Effect of the first turbine nozzle
4. Compressor interstage bleed and turbine cooling air bypass,
which was allowed for in setting the test point.
The bleed air quantities were included in calculations. Turbulence factors,however, were not included, but are not known to be of significance.Pressure level effects were found to be negligible. The effect of thefirst turbine nozzle was not determined.
79
,, nmnunnm um nnuu nL~nn n uamn inu nn u ra n n Imnuuunmmunuu mnn nlJu-
In some cases, the engine combustor operating pressure could not bereached in the laboratory combustor because of facility limitations.
The T53 combustor data consist of:
1. Combustor test rig operating data (fuel, air, etc.)2. Averaging probe gas sample data3. Traversing probe gas sample data
The combustor was operated at conditions simulating idle to full poweras shown on Table L During the 60-point probe traversing operations,averaging probe data were recorded after each 10 or 15 points. Thegaseous components output was converted to ppm and Emission Index(EI, lb/1000 lb fuel). A plot of CO, hydrocarbons (HC), NO, andNOx as a function of F/A is shown in Figure 52. Some observationsfrom these data are:
1. Trends of HC and CO are as expected, with large decreasesas simulation of high power is approached.
2. NO and NOx increases as expected as simulated powerincreases
3. The difference in idle F/A seen by the traverse average andthe four-point averaging probes can be traced directly to thelocation of the four averaging probes, By selectively aver-aging traverse probe data for locations identical to the fixedprobes only, identical F/A's were obtained.
Concurrent with the 60-point gas analysis profiles in the combustorexit (6-degree rotation angle interval), temperature profiles were re-corded with 5 thermocouples, spaced as shown in Figure 9. If weassume that combustion efficiency is constant around the combustor,then average thermocouple temperature at a point on the combustorcircumference should be proportional to average fuel-air ratio fromthe gas analysis. This is exactly what happens. Results of tests atsimulated idles 30, 60, and 100 percent of full power are shown inFigures 53 through 56, respectively. The significance of the closecorrelation between the two plots is that two entirely different typesof measurement produce very similar results. The absolute thermo-couple temperature measurement is low because of radiation and con-duction losses, but the perturbations of temperature In traversing thecircuit are valid.
80
------ ----
to NOXAS N0.2N
A0OS I.030 .0! J .014 .016 .019 .0.10 .7022 .2 .026
.3530) NO AS N021 0 CAR"O MONOXIDE
I 0 HYDROCARBONS
SOLID SYMBOLS: AVERACP
HYDROCARWO4
S.
Figure 52. T53 Combusetor Rig Emiusions Versus Fuel-AirRatio, (Cruciform Prabe).
81
1400TEPRTE
.4 1200 (VRG F5
1000.
800
.018
.016
.014 rE-I AI
.012 .
.010 -rRS
.008
.006
0 20 40 60 60 100 120 140 160 1.80 200 220 240 260 210 300 320 340 360
" " VBu s 1 " W -O I G
Figure 53. Comparis on of Average Traverse Temper-ature and Fuel.-Air Ratio From Gas Analysis -
T53-L-13 Rig Simulation of Idle.
TWONRPATUR(AWMMOP
1500 I"
1400
1240
.016 M041t 1
Ole.
*30 40 0001"-1 1in I" 18 I" N "30 24 3" IN 30 11034340
Figuire 54, Coniparisono.-o Average Traverse Tempera-ture and..FueX-Air Ratio for Gas Analysi s -T63-Lwl 3 Rig Slmulatioa of 30 Percent Power.
TEMPERATURE (THIERMOCOUPLE)
1600
1500
R 1400
1300 I 'FUEL-AIR RATIO ( A AALYSIS)I
.020 FNS
. 018
E .016
.014
0 20 40 60 80 100 120 140 160 130 200 220 240 260 280 3;0 320 340 360
TRAVERSE POSITXON- DEGREES FROM TOP DEAD CENTR
Figu~re 55. T53-L-13 Rig Simualation of 60 Percent Power,
11001
0383
The "cold" spot in the combustor exit for "idle" power (Figure 53) wasfound to correlate precisely with a lack of fuel in that area. This waslater found to be caused by malfunctioning fuel nozzles.
The level of concentrations of each pollutant has been measured in theT53 combustor with good precision and repeatability.
A complete set of detailed concentration plots of the T53 laboratory rigtraverse data recorded at 6degree intervals is presented in AppendixIL The preceding comparison in this report shows the close corre-spondence between the F/A profile and the temperature profile.
Other aspects of the traverse data from Appendix II which can beutilized for improvement of combustor design a.re:
. If one compares the F/A traces of the T53 with those of theT55 (Appendix IV), a significant difference appears. At idle,both show large random variations due to the poor mixingwhich is characteristic of low-pressure operation. At thethree higher power settings, the T53 traverses show largervariations than the T55, and these variations are of largerspatial extent. The T55 profile is characterized by sharp,short fluctuations that diminish as the simulated powerlevel increises, while the large, emooth varlations of the T53do not vanish at high power. This ilicates that the largescale (or circumferential) stirrin of the T55 is superior tothe T53.
2. A comparison of the T53 F/A traverse at the 30, 60, aad 100percent power levels shows that most of the characterist.csof the traverse carry through from one simulated powersetting to the next. This is also true of the NO and NOxprofiles. At the higher power settingsthe incompletely re-acted species (CO and HC) tend to vanish, and the profileslose meaning. Hence, the only similarity that carriesthrough Ls for the CO between 30 and 60 percent.
3. Comparative study of the El and ppm plots for CC, HC,NO, and NOC will show that the El plots are considerablysmoother than ppn Since the El is the ratio of pollutantto fuel-air ratio# this smoothing means that each of these
84
pollutants is partially proportional to fuel-air ratio. Onewould expect this for NOx , but the fact that it is also truefor HC and CO must mean that the primary zone is on therich side and that the richer regions tend to be quenchedbefore combustion is completed.
4. The correspondence in detail of the NOx profile to the F/Aprofile is so strong that one could infer the shape of the NO,profile from a simple temperature traverse. While there issome coupling between the HC and CO and the F/A, the rel-ative magnitude of the fluctuations is very different and theform of the profile could not be determined from a tempera-ture traverse. However, there'is a correspondence betweenCO and HC. As combustion efficiency increases, both CO andHC decreasewith CO decreasing at a slower rate than HC.The trends are similar to those shown in Reference 8, andthe ratio of CO/HC is a function of combustion efficiency andcombustor style.
T53 Engine Data and Results
T53 engine data consist of:
1. Engine operating performance data (fuel flow, airflow, etc.)
Z. Cruciform (averaging) probe exhaust measurements for gascomposition and smoke
3, Single-point traversing probe measurements for gas compo-sition/
Engine operation performance data were recorded for each data pointwhere the engine power was changed, as in a performance power test.For the long-term steady-state tests, during which time the single -point gas analysis probe was traversed, engine data were recorded at15-minute intervals in order to establish that operations weresteady. Engine data are listed in Reference 5.
Cruciform probe data included average CO, NO, NOx# and hydrocarbonpolutant data, shown plotted versus percent power in Figure 57. Adiscontinuity is shown between "bleed open" and "bleed closed" to de-note the bleed closure. The changes in pollutant concentrations areas expected. CO and hydrocarbons rise steeply at low power; NOX
85
10
NO as NO2
CLOSREC OXIDE as NO2M 9*~~-BLEEDCLSR
o lI i - - I A I
0 20 40 60 80 100
3 7.24 J39.783. 936.81
25? O
20 0 NITRIC OXIDE
0 CARBON MONOXIDE
'4 ~ HYDROCARBONS
ENGINE CRUCIFORMPROBE AVERAGE
'4 BLEED CLOSURE
o 10
'40 HYDROCARBONS
CABO CABONONOXIDE
0 20 40 60 80 100
PERCENT POWER
Figure. 57. T53-L-13 Engine Emissions Verus Zower (Cruiiclowm
Prob).
86
iV
increases with increasing power. Carbon monoxide concentrationsat low power are high, and are shown as a discontinuity on the upperpart of the CO plot.
Single-point probe data were recorded for 73 data points (61 positions)for determining the exhaust gas profiles and correlating the resultswith cruciform probe data. Data were recorded at idle, 30, 60, and100 percent of full power. The average of the single-point concentra-tions and the cruciform probe data are compared in Figure 58.
The single-point probe data were used to plot the concentration grad-ients on three diameters for NOx, NO, CO, HC, and F/A for thefour test conditions: idle, 30%, 60%, and full power. These are shownon Figures 59 through 62. The general trend is an increase in thegradient a each component as the absolute concentration increases.We note. Lso that aomewhat higher concentrations of hydrocarbons,and CO to some extent, exist near the tailpipe walls at low power,although the F/A does not show a particular wall increase. At highpower and high F/A, the NO and NOx gradients tend to correspondto that of F/A, with higher values near the wall.
Some irregularities and discontinuities are noted on the diametral pro-file data. In many cases, these are a result of slight variation inoperation. The test time covered a period of about 3 hours. Duringthis time, the ambient air pressure, temperature, wind velocity, anddirection could change. To determine the extent of these effects, plusthose associated with changes in engine airflow, fuel flow, etc. , thecenter point was used as a reference level and was sampled on eachdiameter sweep of the probe. The time average center point concen-trations were used to correct or "normalize" the surrounding datapoint position concentrations. The results have been plotted in Appen-dix II for the four power settings and components CO, HC, NO, NO x .
In addition, combustion efficiency and F/A were plotted. For mostof these plots, the exhaust gas is quite uniform. Nonuniformities thatwere measured in the combustor exhaust in the laboratory combustorare not pronounced in the engine exhaust. The large gradiei,t, of con-centration reported in the exhaust of large fan jet engines (JT9D)(Reference 34) are not observed in the T53 exhaust. There arenoticeable similarities between F/A profile gradients and NO (or NOx)gradients for the higher power points, as might be expected.
87
10
H NITRIC OXIDE as NO2
0
39.78
37.24 000 36.8.30-
a NON
25 13 NITRIC OXIDE
0 0 CARBON M(ONOXIDE
200 HYDROCARBONS00 ENGINE CRUCIFORM0 RBEAERG
15.
10. 0
5- CARBON M4ONOXIDE
.010 .015 .020
FUEL-AIR RATIO
Figure 58. T53 Engine Emissions Versus Fuel-Air Ratio.
88
NITRIC OXIDE
I I
II. 11I01.
.013 FUL-A IN RATIOI
I I L7' lm 11a&0 1* o
Figuire 59. T53 Engine Idle Diamzetral Profile.
89
81 N O X
f70 i ,-
I NITRIC OXIDE
I' IL
CARSON MONOXIDE
"or I,
'il
I 0P10,
.1 AIR RATOXIOE
013-
'~O "°W
Figure 60. T53 Engine 30-Percent Power* Diamnetral Pr'ofiles.
90
4 /
i i/
NOX
100I
501~oi 76 re~~ee
PAL AI R MAIO
191
N X
ISO-x
iI t I
i I -,1 INITRIC OXIDE
i H
, I I I
ISO I
f) 10 L
i[ ilit-""a
all-
U' IN', .016.o
B il Ii I I Jill "- i Il t I a i [II
Im " 110 30000 11100 so.
Fiqure 62. T53 Engine Maximum Power -Diametral Profile.
92
In addition to the contour plots of combustion efficiency at each powerrating, a plot was made of combustion efficiency versus percent ratedpower (Figure 63). Both of the two ascending and descending powertests are plotted. Divergence and data scatter at the low power end isas much as ± 5 percent at 98 percent. At high power, scatter is of theorder of 0. 05 percent or ± . 025 percent. An interesting aspect of these"up and dnwn" performance tests is that there appears to be somehysteresis on the return. Those data will be compared in a Lter sectionof this report with respect to NO formation
These data lead to the following conclusions regarding the design ofaverage sampling probes for Lycoming engines:
1. Probes should be designed for a systematic variation in theradial direction; i. e., the equal area design concept iscorrect.
2. The maximum number of major circumferenti, 1 vaviatior, Eobserved indicates that the cruciform probe with four radi-lbars is adequate to obtain a representative sample. I oneuses the isopleth plots to calculate the value that a cruci-form probe would read, they agree, in all cases, withinabout 3 percent of the traverse average.
3. The random spatial variations are probably no larger thanthe time variations3 this means that the cruciform probewith a sample time of 2 minutes is preferable to thetraverse that takes several hours.
Smoke measurements, recorded concurrently with the gas analysis,were converted to AIA smoke number per Reference 6. The resultsare plotted versus power in Figure 64. The peak smoke number mea-sured is 15, which is well below the visible limit of 30 to 35.
Comparison of T53 Combustor and Engine Emissions
Data from the T53 combustor and engine were examined to learnwhether laboratory combustor exhaust gas data could be used to cor-relate with the engine exhaust gas profiles. The laboratory combustor
93
N.L
U. 0
U.
04 98-
Cd,0 FIRST RUN* DOWN
0 aup&ONSECOND RUN
960204i4060 80 1OO
% POWER
Figure 63. T53-L413 Engine Comnbustion EfficiencyVersua Percent Power.
20 0 RUN 1 (100% POWER - 1400 lip)R UN 2
0
10
0 20 40 lot010
PBNCIW PontU
Figure 64. T53-L-13 Engine AIA SmokeNumber Versus Percent Power.
94
probe contains 5 ports (Figure 13) which ingest the gas and arrive at anaverage mixture for a sector of the exhaust. This composition wascompared with an engine traverse of gas composition along a radial cir-
cumference that corresponds tu the geometric centroid. The two areplotted in Figure 65. An examination of the two profiles reveals nosimilarities, although the average F/A values are similar, as would beexpected. The conclusions are:
1. Any small circumferential concentration profile that is presentat the combustor exit is essentially wiped out by mixing in theturbines and exhaust ducting.
Z. Aerodynamic flow in the laboratory test may be different enoughfrom the engine flow so that a comparison of profile detailmay be meaningless.
Emission level from the combustor test wa.- compared with emissionsfrom the engine. Because the engine F/A is not the combusfor F/A,comparison of the two requires adjustments. Engine horsepuwer waplotted against both engine F/A and combustor F/A (Figure 66). Theairflow adjustnents included compressor bleed and cooli.ng air forthe turbine, as discussed previously in this report. With hlis ccrrec-tion applied to the engine data, a plot was made of pollutants versus
combustor F/A (Figure 67). Agreement between cruciform (averaging)probe, engine traverse average, and laboratory traverse average isexcellent for nearly all components. (The NO values from the enginetraverse average are higher than the other two values.)
The good agreement between the three measurements in the laboratoryand on the. engine demonstrates that:
1. The measurements in the laboratory can be used to predict
engine emissions.
.Z$ Conditions of test in the laboratory closely approximate englup.operation from an emissions point of view.
3, The precision of the measurements is obviously satisfactoryand reproducible over a period of several weeks and undervaried testing conditions.
I9
1.9• N ,' ' .
0
0M
14K00
00
fo 0
E-4-
cl0
Uo U 41(A
co
NV
M P4 P4 M 4 .0
olLkl lv-w 01 VIV12a
96C
v
11% INTERSTAGE BLEED11.38% COOLING BYPASS BLEED
1600
1400 0 TEST #1 - COMBUSTOR ONLY
0 TEST #2 COMBUSTOR ONLY'f . TEST #1 ENGINE/
1200/ /.
1000 I
600
/
600
200
, FLGHT IDLE 6OPERATING IDLE
.010 .012 .014 .016 .018 .020 .022
FUEL-AIR RATIO
Figure 66. Fuel-Air Ratio Venus Shaft Horsepower for T53 Engineand Combustor.
r9
15
0"~10 NOX as N02A
NITRIC OXIDE as NO2
40-
35~j2 5
0A A& NO,
2 0 NITRIC OXIDE
S20 @ 0 CAREOCN HONOXIDE
2 Z * ~HYDROCARBONSENGINE CRUCIFORM
w0~ 1 PROBE AVERAGE
10
0 ol
.010 .015 .020 .025
COMBUSTOR FUEL-AIR RATIO
Figure 67. Comparison of T53-L-13 Emissions From Engineand L~abora~tory Combustor Teats.
98
V i.
4. The preponderance of evidence from the three measurementsprovides solid ground for a statement on emission level for
this engine.
T55 Combustor Data and Results dSAs with the T53 combustor, the T55 data cons,.,t of combustor test
rig operating data, averaging probe data, and traversing probe data.
The combustor was operated at conditions simulating engine idle to
full power (Table I). Maximum power and 60 percent power conditionswere simulated with temperature, but not with pressure, because ofcompressor facility limitations. During 60-point traverses, averagingprobe data were recorded for each 15 data points. This served thepurpose of checking the combustor operation for possible variationsas time progressed, and for obtaining averaging probe data. Gaseouscomponent output was converted to ppm and to Emission Index (EI).
A plot of emittants CO, HC, NO, and NO is shown in Figure 68 as afunction of F/A. Obseivations from thexe plots show that:
1. Trends of CO and HC are similar to those from the T53combustor; there are large reductions in concentration aspower Is increased from simulated idle to full.
2. Increases in NO and NO x occur, as expected, as simulatedpower increases.
3. The "traverse average" compares closely to the value readby the four averaging probes. Differences can betraced to the location of the four probes with respect tothe shape of the emission profiles; I. a., the four probes
.were not at representative locations in the traverse.
As with the T53, the T55 temperature profiles were recorded with a5-thermocouple rotating probe (Figures 12 and 13) while the gas sampletraverse was being made, and similar resulta were obtained. Tempera-ture peaks and valleys correspond almost exactly with F/A peaks andvalleys at all flow test conditions (idle, 30, 60, and 100 percent power)(Figures 69 through 72). These results again substantiate the correla-tion between thermocouple gas measurement and gas analysis.
S99
b "'
10o NOX as NO2
.~.A-II7NITIC. OXIDE as NO2
55~ 00
500A ANOx
E 0 NITRIC OXIDE
o 45- 1 00 CARBON MONOXIDE
151 0 HYDROCARBONS
ARBON 0ONXID
~ HYDROCARBONSo'.010 .015 .020 .025
GAS ANALYSIS -FUEL-aAIR RATIO
Figure 68.- T55 Laboratory C ombtutor Emiselons VersusFuel-Air Ratio.
100
10o NOX as NO2
NIRCOXIDE as N02
55
00
A ANOX
V-45 *0 CARBON MONOXIDE
~15 0 HYDROCARBONS
10
ARBON HONOXIDE
5-
010 HYD~RO N
GAS ANALYSIS FUEL-AIR RATIO
Fiue68. T55 Laboratory Comnbustor Emissions VeruusFuel-Air R~atio.
100
4-4
00
0 44a4.
o
0 C
100
- - - - - -- - -
00
00
N0
0
0
U2
4P4
P4P
r C14
100
K0
04
00
0
0
P4 4
E-4 -
~ H "H
0 P 0
N P4
103
M.4
0
- '00
00NU)
Hw Pq
N 0
H
0 $
'-0 rzo g 0
E--4; ~ -
1-4
UNq
0
0
1044
Complete plots of the T55 rig traverse gas composition data arepresented in Appendix III. The T55 F/A traverses show variationsover short distances which diminish to a steady value at higher simu-lated power. From a combustor design viewpoint, this indicates goodcircumferential mixing. As with the T53, the characte-istics of thetraverses tend to recur at each successive power sel.ting. This holdsfor all the pollutants, as well as F/A, except at highpower simulationwhere HC becomes minute, and traverse detail vanishes.
During the T55 "idle" traverse, a valve was left open in the sample linefor the central one-third of the traverse; this resulted in sampledilution with ambient air. As one may estimate from the F/A profile,this resulted in roughly 1.5 parts of air to each part of exhaust gas.This dilution does not affect the calculated value of EI or combustorefficiency because these are evaluated from- a ratio of exhaust gascomponent concentrations rather than an absolute value. Notice thatthe ET's for CO, HC and NO are not significantly shifted in this sectionof the traverse. Such is not the case for NO , which shifts downwardto just above the level of NO. Apparently the disturbing effects of theother exhaust components were eliminated by the heavy dilution. Thiseffect may be an instrument phenomenon, because the NO level doesnot change as it would if NO were being created in the sample line.
x~When one compares the plots of E1 with those of ppm, the NO and NO x
are substantially smoother for the El traverse, which once againdemonstrates the substantial relationship between NO and F/A. Forthe T55, a similar conclusion cannot be drawn for the CO and HC asit was for the T53. Here the amount of unburned species is quiteindependent of the local F/A. Apparently the mixing is good, and theprimary zone is lean enough so that the richest zones of the cornbustorhave no more tendency to leave unburned components than do theleaner zones.
The correspondence of the NO and F/A profiles is sufficiently goodto permit the shape, but not tir level, of the NO profile to be estimatedfrom a simple temperature traverse. CO and HE show no detailedcoupling to the F/A, but are coupled to each other up to the pointwhere the HC reaches a negligible concentration at or below 60 percentpower. The ratio, CO/HC, is once again a reasonably consistentfunction of efficiency. although it is not the same dependesice observedfor the T53 data.
105
T55 Engine Data and Results
T55 engine data, similar to the T53 data, consist of:
1. Engine operating performance
2. Exhaust gas measurements from the cruciform (averaging)probe
3. Exhaust gas measurements from the single-point probe
As with the T53, both engine data and gas analysis data were recordedat each power setting as the engine operation was increased from idleto full power and down again. For the steady-state operation requiredfor single-point probe traversing, engine operation data were recordedat 15-minute intervals. Engine data are tabulated in Reference 5.
The T55 engine emission levels from cruciform probe "performance"tests are shown in Figure 73 for idle through full power. The discon-tinuity at bleed closure is obvious. NO, NO , and HC emissionsrepeat within the experimental error for twoXtests. For CO, twolevels of concentration result from two tests. The reason for theCO level difference is not obvious. Agreement of concentrations ofother constituents for the two tests is within the experimental error.Trends of NO, NOx , HC, and CO are similar to those from the T53engine, as expected. Comparisons of values with other engines willbe made later in this report.
Data from the single-point probe were used to plot the concentrationgradients for NO, NO , CO, HC, and F/A for four test conditionsx
idle, 30 percent, 60 percent, and full power. These are shown inFigures 74 through 77 as profiles at three diameters across the exhaust.General trends oi the profiles are similar to those of the T53. Again,some discontinuity is noted for two halves of the traverse, a functionof slight changes in operation and ambient conditions. NO measure-ments exhibit more variability than the others, and, in general, indicate10 to 20 ppm more than NO. These characteristics will be discussedin more detail later in this report. Some erratic behavior is displayedby the CO measurement at 30 percent power, and the level of COappears to be low. It is suspected that the detector may have beensomewhat out of adjustment during this test.
106
p10NOx as NO2
asN0
0
50
20' 0
20 1BLEED 0 Nj~LOSURE
15 A NOX
U 0 NITRIC OXIDE
Lo 0 0 CARBON MONOXIDE
010 *OHYD)ROCARBONS-ENGINE CRUCIFORMV U.'- PROBE AVERAGE 2 CRO
RUN I. MONOXIDE
BLEEDECLOSUE HDR O ARB O US
jPERCENT POWER
Figure 73., T5-L-ll Engine Emissions Versusa Percent Power
(Cruciform Probe).
107
tt
I40 x
04
lo L IIi i iI Ii0, NITRIC OXIDE
Z
20[[
6 0
o 6:0- 1
' ' S U
50
II sool I I
II ,i*YDROCARBONS
02 I10 ft e
I 00 c/, 1. 9 c/L 3 11. C/l, 530' 90* 150'
Iiigti'e 74. T53-L-IIA Engine 470 Lb/Hi Idle Diametwal Profilea. ;
108
V4 .0.. ...... .. .. .. 00 - .+ : . i + .x . .:/ :::. " -: .. .- ".... , ~ ~ ~ il ........ A I..... a,,+ ,, .. ALI.+ . :. -.,.. . ., , . ,-_
. ... . . . ... . "/ 1. . . .9 CA 3 11 C L 5 " :' "• ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ILC O'CLOCK,,,."..,. .,.,.+ + ,:y : :+...,.3 0 •9 0
, "
Fi ur 74: + :. ' :,. ." .. T5 - - 1 Engine 470 L 'H Idl •D'.'!b:"iam t a P rofiles. ' :' :+ , :: " " . '
i i i i I i iI III II I I ~ ii i I I II I iiIi IiIIIIII ilog• I
NOx
I I S
3 0
40 - NITRIC OXIDE
30 -
0 32 I I
CARBON MONOXIDE
z 120z 110
100 I i
> 80- i
7 0
60 L
30 HYDROCARBONS
30
I I I10J
IFUEL-AIR RATIO
.015
- .014
i .013
. 7 C/L CA 3 11 C/ 5
OICLOCK O'CLOCK30 0 90 0 150 6
Figure 75. T55-L-l1A Engine 30% Power Diametral Profiles.
109
llIIo
NOx
70L oI I0
50I
NITRIC OXIDE
60I I
--z m 50
~40
CARBONMONOXIDEo1301 1
SI I
120
0 1oo0
07
go L Lp-
0 r i
;.. o iFUEL-AIR RATIzOi
01
017
ol I.0-kil7 C/L 1 9 C/L 3 11 C/L 5
O'iCLOCK 0' CLOCK(300 900 1500
Figure 76. T55-L-11 Engine 60°jo Power Diametral Profies.
!--- 1to
100%0ex
80
90 NITRIC OXIDE
90
170
120-
10
130
80 170 L
FuelAirati atFUEL-AI Power.
300 90 'LC 5, 'LC
Fiur 77 N,,1 Egn imtalPoie f mtat n
Ful-i Rai tFalPwr
As with the T53, the center-point gas composition in the T55 exhaustwas used as a reference level to correct other point samples to the"normalized" level. Contour plots of concentrations could then bemade, as shown in Appendix IV. The profiles for the most partindicate nearly complete combustion at high power, and relativelyflat profiles, indicating good mixing.
After one test at 60 percent power, it was found that the engine oilseals -had deteriorated (Reference 5). * This test was rerun. Tocompare the effect of oil seal leakage, the data were plotted (Figure 79)and compared with a similar test when the seals had been replaced(Figure 78). A marked increase in hydrocarbons is shown for theoil leakage case. The amount of leakage measured on a short testthe next day was 2 quarts per hour +15 percent. If uniform leakagecan be assumed, this would amount to 88 ppmC, as compared with themeasured value of 30 to 40 ppmC. The difference between these twovalues can be explained if we assurn'e that the leaking oil was notdistributed uniformly in the airstream, and that some of it madeits exit by other means. There was no indication of hydrocarbonsaturation or chromatographic effects in the sampling lines from highconcentrations of heavy hydrocarbons. "Normal" oil consumption hasbeen measured at 0. 25 quart per hour.
A plot of HC concentration ,rersus point sequence (or time) at 60 percentpower shows HC increasing, as time progressed and the oil sealdeteriorated (Figure 80). Also shown is the small HC concentrationwhen the test was rerun after the seal was repaired. The reductionin HC with the new seal is dramatic.
Combustion efficiency was calculated from gas analysis and plottedas a function of engine combustor F/A in Figure 81. Threetests were made, operating the engine from idle to full power andback. (Two tests were made on one day and one on the second day.)The significance of the three tests is that the combustion efficiencycalculations are very close, even overlapping, indicating repeatableresults from run-to-nu and day-to-day, An examination of Figure 81for hysteresis shows only a hint of this type of nonreproducibility, andnothing conclusive,
*Smoke was visible in the engine exhaust during the seal failure. Nosmoke measurements were made during this-period.
lIlZ
'.i
• . " .. ... ... ' '? ' ''. " .. .. .. " . . .. ... " "'? ' °- ' . ' " :'" :''< :- " : '=
i . '.. .. . . - .-
" . . . / .. ,. . . ' • / \T. , : -- : , ' = ' . :. i': = :.:' " , : . ' * " ' - '. .
0 00
aP 00 0 0 0
at 60 Pe0n Pwr
j~~0 00-O
Li'is-
Fiur 9.T5 nin soltho N p0C
at 60 0ecn Poe 0 uin an9 OloSeal ::lu
K~71 10S. ~ ~ A
I~~ 0 %'
0j
00
41
uJj
4 04
40
I-j
o 4 .4.)
10014W0 UP FIRST RUN
t~up SECOND RUN
IL A DOWN
000
PERCENT POWER
'1
Figiare.81. T55-L-11A Engine Combusetion Efficiency VersiusPercent Power.
Smoke emission data for the T55 engine are shown on Figure 82. Twotests were made, and the agreement between them is excellent inlight of the AIA smoke number accuracy specification of +3 (Refer-ence 6). A marked increase in smoke concentration is shown as powerincreases, with a full powea reading of slightly greater than 45. Smokewas not visible in this engine exhaust except when there was an oil sealfailure. There was no known oil leakage during the testing portrayedin Figure 82.
Comparison of T55 Combustor and Engine Emissions
Similar comparisons of "combustor exit F/A" and "engine exit F/Alprofile were made for T55 data, as was done for T53 data. A typicalexample is shown in Figure 83. Combustor sample data were takenat 6 degree rotation intervals with the 5-port averaging probe. Enginedata were those from a single-point probe sampling path with theradius at the centroid position. Again, no similarities in the profileswere found. The conclusion reached is that the engine exhaust gascomposition profile cannot be predicted from combustor exit compositionprofile.
To further evaluate the engine exhaust as compared with the combustorexhaust data, we performed a similar procedure as for the T53 engine.A plot of engine horsepower versus F/A of the engine and of thecombustor was made from engine performance data (Figure 84).Compressor bypass bleed and turbine cooling air were included incalculating F/A, By using this information, pollutants for bothcombustor and engine could be plotted as a function of combustorF/A as shown in Figure 85. With three measurements, cruci-form probe in the engine, engine traverse average, and laboratory
/ traverse average, we find agreement close to within the experimentalerror of any one of these measurements. Since these tests wererecorded over several test periods and with two separate pieces ofequipment (laboratory rig and engine), the agreement is very good.The large spread in CO data appears to repeat for the three measure-ments--aa indication that it is not fortuitous, even though the reasonis not perceived.
Again, the good agreement between laboratory and engine measurementsdemonstrates that:
1. Laboratory measurements can be used to predict engineemissions.
116
IIi
0(100% POWER =3750 HP)
A RUN #2
0
BLEED CLOSURE
r 130A
A
20 NOTE: SMOKE NUMBERS FOR/IJ DESCENDING POWERI ARE SLIGHTLY HIGHERI THAN FOR ASCENDING/ POWER
0 20' 40 60 80 100* - PERCENT POWER
F'iguire 82, T56-L-11A Engine AIA Smoke Nuamber Versusa PercentPower.
X1~
_____N __ __ __ _ 0
00
04
E-4 N 0 UI
0 0 0
~~0k
94~ 0 l1
0 004 .. A
'0w
oc
in
0 0 0
MU Ma1a a 011W UV1a
118
4000 ~___
15% BLEED OPEN AIR LOSS/
13.A% COMBUSTOR BYPASS/
0 TES #1 BLEE OPE
o TEST #2 - BLEED OPEN
A TEST 2 - BLEED COE
3000 A TEST *1 -BLEED CLOSED
13 TEST #1 - ENGINE UNCORRECTED
0 TRAVERSE AVERAGE
2000
BLEED CLOSED
,P.(.OIBLEED OPEN
OPERATInNAL IDLE
'*'- 1 4- - LIGHT IDLE
.010 .012 .014 $016 .018 .020 .022 .024 .026
FUEL-Alk RATIO
Figure 84.- Fuel-Air LRatio .eraiie Shaft H~orsepower for T55 Engineand Combustors{ 119
NO,, as NO2
AA
A ~ NITRIC OXIDE as NO2
49
40130 ~~~~U 0 IRCOIE Aezeo
* 0 CARBON MONOXIDE SinglePoint Probe* HYDROCARBONS JTraverse
25- ENGINE CRUCIFORMo PROBE AVERAGE
20-
BLEEDCLOSURE 4
15.
CARBON MONOXIDE
0 RUN I10 - RUN 2
00
.010 .015 .020 .025 .030
COMBUSTOR FUEL-All RATIO
Figure 85. T55-L-11.A Emiusions Comparison of Engine to LaboratoryCombusator Emissions.
iZ. Laboratory test conditions producing emissions closely
approximate engine operation, even though the pressurecannot be exactly reproduced.
3. Tests produced over a period of time can reproduce similarresults.
4. A good basis for engine emissions levels has been established.
CORRELATIONS
Correlations of T53 and T55 NOx Data
The scatter of some of 'he T53 NOx data was analyzed by investigatingthe possibility of hysteresis in the combustor performance withincreasing or decreasing power. This was first found in T53 combustionefficiency, as shown on Figure 63. Two tests were made on successivedays with an inlet ambient temperature change of about 100 F. Thehigher combustion efficiency occurred at the higher inlet air tempera-ture, as might be expected. The major point is that after a "warming-up" period, combustion improves somewhat. Likewise, NO x productsincrease. The effect of this NOx increase in the T53 engine is shownin Figure 86 for the same tests. There appears to be some correlationbetween combustion efficiency and NO produced.
It is interesting to. note that the engine exhaust "traverse average"data points (Figure 86) of four tests on different days over a periodof 12 days all lie in and around the data from the engine "up and down"performance test run. Ambient temperature during this period was400 to 50 0 F, and specific humidity varied from .0034 to .0044 poundof water per pound of air.
/
A similar plot of combustion efficiency (Figure 81) and an analysis-" of T55-L-1l nitric oxide data were made (Figure 87). The data scatter
In not quite so pronounced as for the T53 engine. If hysteresis exists,it is hidden by data scatter. The change in concentration betweenthe two test runs is small, of the order of 5 percent (Figure 87).Traverse tests, recorded on 6 different days over a period of 18 days,show scatter of the same order as the scatter from a single performancetest.
' t'l~l N
I &
" %-N .
DATA CORRECTED TO .01 LBWATER/LBAIR
90
8DAY POWER0
0 FIRST INCREASING0 FIRST DECREASING
ASECOND INCREASING- /A
6A SECOND DECREASING
5 0 TRAVERSE AVERAGE 4
44
A~
o ~ /z ' i 4
200 30 40 So O
COUSO AI 4' ZUATR
Fiue8.Ilt i eprtr Vru ircOxd mte oT5-I3 nie
7
DATA CORRECTED TO .01 LB WATER/LB AIR0-
6
AA
4/
AA
0/2 A0 75 .05
TET# O 9/28 60%R 62 .0076*
o 9/2 I00E 70 .01305*
09/29 1100% 163 1.01195'
*CHANGE5 DURING TEST BY 10% OR MORE
00400 500 600
COMBUSTOR AIR INLET TRMPERATURE - I
Figure 87. Inlet Air Temperature Versus Nitric Oxide Emitted for
T55--11Engine.
i. -, .
The T53 and T55 engine NO data were compared with each other andalso with a group of engine gata from Reference 28. The results areshown in Figure 88. Both T53 and T55 data bands lie mostly withinthe data band spread of Reference 28. The T55 NO is about 30percent less than that of the T53. The combustor residence time inthe T55 is approximately one-half that in the T53. Because NO x
formation is a time function, the difference is reasonable.
Lipfert's compiled data (Reference 28) are for many different gasturbine engines, and obviously, they do not all have the same combustion
chamber residence Ime. Most of the T53 and T55 NO, data
lie within this band. It can be logically assumed that differentcombustor residence time could account for the major portion ofdata spread. However, a differeilce in slope for both T53 and T55is noted on Figure 88.
Other Correlations and Comparisons
The three measurements, (1) engine cruciform probe, (2) engine
traverse average, and (3) laboratory traverse average,were used to
calculate combustion efficiency for the T53 and T55 engines. The
variation in the calculated combustion efficiency is in nearly all
cases less than 0. 5 percent (Figures 89 and 90). At the upper power
range, agreement is of the order of 0.1 percent for nearly all cases.
This agreement exists in spite of the time, operating conditions, test
rig versus engine, and measurement variables. Both exhaust gascomposition and measurement precision for both conbustor and enginetests were in close agreement.
Another comparison of combustion efficiency in both Lycoming T53and TSS engines with a group of gas turbine results from Reference 4is shown in Figure 91. The Lycoming engines are grouped near theupper portion of the combustion efficiency band. Becausfe pollutantCO and HC are directly responsible for loss in combustion efficiency,this infers that these two engines are among the better gas turbinesfrom the standpoint of CO and HC pollution.
Summary of T53 and T55 Gas Analysis
A brief srnmary of the gaseous emission resuits from these testsis shown in Table VI. The emission values listed are average numbersto provide the reader with a quick comparison. More precise valuesand their range must be obtained by closer exarninaqion of the data.
1Z4
REFERENCE: LIPFERT
30 DATA CORRECTED TO .01 LOWATER/LB AIR
20
S10
S9
8
6
.4
2
200 300 400 500 G00 700 800 900
COMWSTOR AIR INLET TENPUANTURE oF
rigare 8.NO x Verusi Inlet Temp. rattire for Several Large andSmall Gas Turbines Compared to T53 and T55 Emissions.
125
100 p~AJ
ENGINE CRUCIFORM9 PROBE
A'.40 ENGINE TRAVERSE AVERAGE
A RIG TRAVERSE AVERAGE
954U?0 ULAI AI
.010 .015 .020 .025
Figure 89. Comparison of T53-L-13 Combustion EfficiencyVersus Fuel-Air Ratio for Engine and LaboratoryData.
100 Aaa
ENGINE CRUCIFORM PROBE
0 ENGINE TRAVERSE AVERAGE.
ARIG TRAVERSE AVERAGE
__
410 .15 .00 .02126RFULAR AT
Figue 9. Cmpaisonof 55--11 Comustr CmbutioEffciecy erss Fel-ir atifo Einean
Laoatr Data.
1264
DATA FROM CAL RPR
LVOIGDATA ON T53& T55 ENGINES
90
rIr G
OwallR PCENT
Figure 91. Comparison of Combustion Efficiency Data Variation1z, Verus Power for CAL Report Engines and Lycoming
T63 and T55.
1 127
4D
ITI-4,4
4)
04. 0 o t N 0ou) 0.4w t- 0' Un N 03 Cf) ~
- N UM Go0n e
I:N
0) 10(, 4 - a
0 fLA 0z z -o z
0 co co go0 N
INNLINI
t N - N N
4 -;k
I Inin 0ALn In'
128
... ~~ ..... ,
COMPARISON OF LYCOMING AND NAVY EMISSIONS
DATA FROM THE T53 AND T55
GAS ANALYSIS
To further evaluate the results of the emission measurements on theT53 and T55 engines, we considered the results from Navy tests onother units of the same model engine as reported in References 2and 3, and compared these data with those of the present tests.The ernission levels versus power for Navy tests are shown for the
N two engines in Figures 9Z and 93. These data are plotted on the samechart with Lycoming data, shown as bands with a distribution spread(Figures 94 and 95). For the T53 comparison (Figure 94), agreementis quite good for hydrocarbons and CO. There was less spread in theNavy data, mostly because fewer data points were recorded. NO?concentration was somewhat higher in Lycoming measured data, and iscertainly explainable in terms of expected measurement precisionand engine variations.
For the T55, agreement was better for hydrocarbons and NO andfor CO at low power. The more pronounced higher concentrationof CO from Navy data at the higher power settings is not serious;however, a good explanation is not obvious.
If we construct an "average" curve of concentration of each pollutantfor each engine, then comparisons are more obvious (Figures 96and 97). The confidence level for Lycoming data is high because:
1. Many data points were recorded.
2. Sample validity was checked by constant F/A calcula-tions and compared with the engine input F/A.
3. Frequent checks were made on instrument accuracy.
4. Emission correlation comparisons between engine and*combustor rig tests all show agreement within the data
band spread (usually 10 percent or less). If we assumethat Navy data are equally valid, then the only measurementsthat appear conflicting are the CO data for the T55 engine.
129" K. Z
10
x
S 5
r343
:-BLEED CLOSURE NITRIC OXIDE as N02
' 0
56.7449.66 51
F45.17 47.56J39.97 A NO1
.0 NITRIC OXIDE
0 CARBON MONOXIDE
20 0 HYDROCARBONS
-ENGINE CRUCIFORMPROBE AVERAGE
"~15BLEED CLOSURE
CARBON MONOXIDF.
0 0 40 60 so 10
PERCENT POWER
Figure 92. Navy Air Propulsion Teat Center T53.-L- I3A Engine Data.
130
10NOX as NO2*.~1
AbN~A
NITRIC OXIDE 0
BLEEDE CRLCIUOE
0
83.8 81. -- BLE.ED CLOSURE
0 OHYDROCARBONS
ENGEN I No C R
10131
C AR 0 N Moll
CARBON OVOXID
5 LE LSR
10
5
0
0 20 40 60 80 100
j4JPERCENT FULL POWER
1~ 40
35fLYCOING DATA
30 NAVY DATA
15
CARBONM4ONOXIDE
10
~~HYDROCARBONS
0 20 40 60 s0 100
PERCENT FULL POWER
Figuire 94. Comparison of T53-L-13A Emission Data Band FromLycoming and Navy Tests.
1 3Z
6
4
00 20 40 60 80 100
PERCENT FULL POWER
30
28
26
24
22
20 - M LYCOMING DATA
18 ~ NAVY DATA
S 16
S 14
... 12
10
6
4
2 HYDROCARBONS
00 20 40 60 80 100
PERCENT FULL POWER
Figure 95. Comparison of TSS-L-1 IA Emission Data Band FromLycoming and Navy Tests*
133
LYCOMING DATA
~ 10 -- NAVY DATA
000
0 20 40 60 80 100PERCENT FULL POWER
40
35
30
25
20 -CARBON MONOXIDE
10 HYDR0CARL4S
5
010 30 60 so 0s 100
PSKINT FULL POWZR
Figaire 96. Comparison of T53-L-13 Average Emission Data FromLycoming and Navy Tests.
134
- LYCOMING DATA
-- NAVY DATA
10NOX as NO2 -8 -
6o -- p - -
0 -2
0 -CI0 20 40 60 80 100
PERCENT FULL POWER
30 *1
24
22
20
S18
S16
o 14
12
8 CARBONMONOXIDE
4
2 HYDR~OCARBONS
0 20 40 60 80 100
PERCENT FULL POWER
Figurte 9?. Comparison of T55-L-11A Avt.!-age Emission Data From~Lycomning and Navy Tests.
135
This being the case, we cannot explain the differences with the Navytest data on the basis of errors in measurement for the T55, sincethere is good agreement for CO for the T53 engine. Therefore,the difference must be the result of a real difference in gas composition,or a difference in methods or techniques of measurement for the Navytests.
COMPARISON OF SMOKE DATA FROM LYCOMING AND NAVY TESTS
Smoke data from the Lycoming tests were plotted and compared withsmoke data from the Navy tests (References 2 and 3), as shown onFigure 98 for the T53 engine. Although the slopes of the curves aresimilar, the peak value of the smoke number is about 9 units higherfrom Navy data. In Reference 2, it is stated the SAE-ARP 1179 wasfollowed in measuring the smoke. The same procedures were followedat Lycoming. If we assume that the numbers obtained are equallyvalid within + 3 smoke numbers, then obviously one of these enginesproduces more smoke than the other. However, smoke should notbe visible in either case.
A similar correlation of curve shape for both Lycoming and Navy datais noted for smoke comparisons in the T55 engine (Fi.gure 99). Again,Navy data show smoke numbers about 10 units higher. The reasons
could be the inherent differences between the two engines, tha differencesin measurement equipment, or both. It is not possible to state whichof these effects are present.
136
0
I 0
.4.D
usI Imu v I S
IA VI NI-
dam am i
13U
CONCLUSIONS AND RECOMMENDATIONS
Conclusions
1. The emissions data obtained in these tests of T53 and T55 enginesis in reasonable agreement with previous data taken on theseengines.
2. Two engine exhaust gas probe configurations were tested:
a. Single-point probe used in a traverse of the exhaust
b. Cruciform ormultipoint averaging probe
Analyzed gas samples from the two measurements agreed within5 to 10 percent of each other. This establishes the cruciformaveraging type of probe as a satisfactory method of samplingthe exhaust gas in these engines. The cruciform probe is byfar the simplest probe in use.
3. Th a laboratory combustor tests provided excellent means ofmeasuring gaseous composition and pollutants, and these datacould be used to predict engine emissions. This was true eventhough laboratory rig operating pressure was less than the
maximum engine design operating pressure. Temperatureiimulation was more important and was duplicated in thelaboratory tests.
4. The criteria used for determining whether the gas sample isrepresentative of the stream were as recommended by theSAE-ARP 1Z56. The ARP specifies that engine (or combustor)independent F/A measurement shall agree with the gas analysiscalculated F/A within 15 percent. In these tests, agreementwas within 5 to 10 percent, or better than required.
5. There was no apparent correlation of tha circumaferential traverseshape between engine and laboratory, nor was there a significantcorrelation in either case to the mechanical structure of the rigor engine. However, the engine exhaust profiles of all constituentswere smoother than the profiles observed in the combustor rigdue to the smoothing action of the turbine and exhaust diffuser.
6. Smoke is invisible in the exhaust of both of these engines at alloperating conditions. The one exception occurred when a T55oil seal failed.
138
7. NO x measurements were in nearly all cases approximately 10to 20 ppm higher than NO measurements.
Recommendations
1. The "Cruciform" or averaging-type probe is recommended assatisfactory for emission measurements on T53 and T55 engines.Further investigations are needed to establish the advisabilityof using this type of sampling probe on other gas turbine exhausts.
2. Questions of NO 2 formation and measurement need furtherinvestigation to improve the reliability of the NO x measurement.
3. A standard calibration gas checking system should be developedso that all agencies engaged in engine emission analysis havethe opportunity to check their analyzer equipment againstestablished gas sample bottles.
139
LITERATURE CITED
1. Nelson, A. W., EXHAUST EMISSION CHARACTERISTICS OFAIRCRAFT GAS TURBINE ENGINES, ASME Paper 72-GT-75,March 1972.
2. Stumke, F. B., Jr., ARMY MIPR AM .DL 71-6-T53-L-13AENGINE; RESULTS OF EXHAUST EMISSIONS TESTS ON (Report),AEFL:GS:er, 10340, Ser. 370, Naval Air Propulsion Test Center,19 July 197Z.
3. Stumke, F. B. , Jr., ARMY MIPR AMRDL 71-6 - T55-L-1IAENGINE; RESULTS OF EXHAUST EMISSIONS TEST ON (Report),AELI:GS:er, 10340, 'or. 322, Naval Air Propulsion Test Center,22 March 1972.
4, McAdams, H. T., ANALYSIS OF AIRCRAFT EXHAUST EMISSIONMEASUREMENTS: STATISTICS, Cornell Aero Laboratory,
Report NA-5007-K-2, Prepared for Environmental Protection.Agency, November 1971.
5. Panas, G., EXHAUST EMISSIONS EVALUATION ON T53-L-13B
AND T55-L-1IA, B-19Q ENGINES: - ENGINE TEST OPERATIONSAND DATA, Avco Lycoming Report R-0113-902-72 and R-0211-906-72, November 1972.
6. AIRCRAFT GAS TURBINE EXHAUST SMOKE MEASUREMENT,SAE Aerospace Recommended Practice, Report ARP 1179,4 May 1970.
7. Rubins, P.M., GAS ANALYSIS EVALUATION OF GAS TURBINEENGINES AND COMBUSTORS, Avco Lycoming Report 4735. 2. 18,May 1972.
8. Toone, B. , and Arkless, R,, THE APPLICATION OF GASANALYSIS TO COMBUSTION CHAMBER DEVELOPMENT,Seventh Symposium (International) on Combustion, Butterworths,London, 1959, pp. 929-937.
9. Perry, J. H., CHEMICAL ENGINEERS HANDBOOK, 4th Ed.,McGraw-Hill, New York, 1969.
140
A
10. Kolesar, K., CALCULATION METHODS USED IN IBM PROGRAMKil0, Avco Lycoming Memo D3-f-026-69, 16 May 1969.
11. Chapier, J., ONE-SPOOL ENGINE BASIC PERFORMANCE DATA,SYSTEM 360/144, Avco Lycoming Memo Program No. E147,30 January 1970.
12. Doyle, B. , GAS ANALYSIS DATA REDUCTIONS SYSTEM 370/155,
Avco Lycoming Memo Program No. K-120, 27 July 1972.
13. Cassidy, F. , Fresia, J. , Tinter, J. , and Chantland, R. , DS-5DATA ACQUISITION SYSTEM, OPERATION MANUAL, AvcoLycoming Standard Operating Procedure, Revised 15 April 1967.
14. CALIBRATION SYSTEM REQUIREMENTS, Military SpecificationMIL-C-4566ZA, 9 February 196Z.
15. C. Glenn, MEASUREMENT AND TEST EQUIPMENT CALIBRATIONSYSTEMS, Avco Lycoming Memo IES-I, March 1972.
16. Dick, R. , and Hartmann, C. H., CRITICAL EVALUATION OF THERESPONSE CHARACTERISTICS OF THE HYDROGEN FLAMEDETECTOR, Varian Aerograph Tech. Bull. 133-67, 1966.
17. PROCEDURE FOR THE CONTINUOUS SAMPLING AND MEASURE-MENT OF GASEOUS EMISSIONS FROM AIRCRAFT TURBINEENGINES, SAE Aerospace Recommended Practice, ARP lZ56,1 October 1971.
18. T53 AND T55 GAS TURBINE ENGINE EXHAUST EMISSIONSMEASUREMENT, Contract DAAJOZ-7Z-C-010Z, U.S. Army AirMobility Research and Development Laboratory, Ft. Eustis,Virginia, June 197Z.
19. Caretto, L. S., Muzio, L. J., Sawyer, R. F., and Starkman, E. S.,THE ROLE OF KINETICS IN ENGINE EMISSION OF NITRICOXIDE, Combustion Science and Technology, Vol. 3, 1971,pp. 53-61.
20. LaMantia, C. R., and Field, E. L., TACKLINGi THE PROBLEMOF NITROGEN OXEDES, Power.,.k"1U 1969.
14t1
N0
21. Mikus, T. , and Heywood, J. B., THE AUTOMOTIVE GAS TURBINEAND NITRIC OXIDE EMISSIONS, Combustion Science andTechnology, Vol. 4, 1971, pp. 149-158.
22. Heywood, J. B., Fay, J. A., and Linden, L. H., JET AIRCRAFTAIR POLLUTANT PRODUCTION AND DISPERSION, AIAA Paper70-115, January 1970.
23. Marteney, P. J., ANALYTICAL STUDY OF THE KINETICS OFFORMATION OF NITROGEN OXIDE IN HYDROGEN AIR COMBUS-
TION, Combustion Science and Technology, Vol. 1, 1970,pp. 461-469.
24. Westenberg, A. A., KINETICS OF NO AND CO IN LEAN,PREMIXED HYDROCARBON-AIR FLAMES, Combustion Scienceand Technology, Vol. 4, 1971, pp. 59-64.
25. Hazard, H. R., NO x EMISSION FROM EXPERIMENTAL COMPACTCOMBUSTORS, ASME Paper 72-GT-108, March 1972.
26. Bowman, C. T., KINETICS OF NITRIC OXIDE FORMATION INCOMBUSTION PROCESSES, Paper Presented at 14th Symposium(International) -n Combustion, August 1972.
27. Cox, F. W. , Penn, F. W. , and Chase, J. 0. , A FIELD SURVEY OFEMISSIONS FROM AIRCRAFT TURBINE ENGINES, U. S. Bur.Mines Report RI-7634 (Dept. of the Interior), 1972.
28. Lipfert, F. W., CORRELATION OF GAS TURBINE EM,1SSIONSDATA, ASME Paper 72-GT-68, March 1972.
Z9. Hilt, M. B., and Johnson, R.H. , NITRIC OXIDE ABATEMENTIN HEAVY DUTY GAS TURBINE COMBUSTORS BY MEANS OFAERODYNAMICS AND WATER INJECTION, ASME Paper 72-GT-53,March 1972.
30. Klapatch, R. D., and Koblish, T. R., NITROGEN OXIDE CONTROLWITH WATER INJECTION IN GAS TURBINES, ASME Paper71-WA/GT-9, November-December 1971.
31. Shaw, H., REDUCTION OF NITROGEN OXIDE EMISSIONS FROMA GAS TURBINE COMBUSTOR BY FUEL MODIFICATIONS,ASME Paper to be presented at 1973 Gas Turbine Conference.
142
32. Keenan, J. H., and Kaye, J., GAS TABLES, Wiley, New York,1957, pp. 157 ff.
33. AIRCRAFT AND AIRCRAFT ENGINES, PROPOSED STANDARDSFOR CONTROL OF AIR POLLUTION, Environmental ProtectionAgency, Federal Register, Vol. 37, No. 239, 12 December 197Z.
34. Nelson, A. W., Davis, J. C., and Medlin, C. H., PROGRESS INTECHNIQUES FOR MEASUREMENT OF GAS TURBINE EXHAUSTEMISSIONS, AIAA Paper 72-1199, November 1972.
14I
lI!I
I
ii
APPENDIX IT53 LABORATORY COMBUSTOR RIG TRAVERSE DATA
This appendix presents computer "Calcomp" plots (Figures 100 through111) of all the emission traverse data taken in the T53 combustor testrigs only. Each simulated power condition (idle, 30, 60, and 100percent) is represented by three separate plots:
1. Performance summary plot showing fuel-air ratio,combustion efficiency, and the separate componentcontribution to combustion inefficiency
2. Emissions in ppm volume for CO, HC, NO, and NO x
(hydrocarbons are ppmC)
3. Emissions index (EI) .in pounds per 1000 pounds of fuelfor each component
Scales for the performance summary plot"are constant, but the scalefor each of the emission plots is computer-selected to attain thelargest value on the scale. Traverse position is in degrees fromthe rig starting point; the T53 rig starts at 1800 (bottom center).This is significant in comparing results from the rig with engine dataor with rig temperature traverses which start at top dead-center.Symbols on the plots have the following meaning:
* Net combustor efficiency
! ( Fuel-air ratio
-CO (inefficiency, emission index or ppm)
Y HC (inefficiency, emission index, or ppmC)
X NO (emission index or ppm)
NO (emission index or ppm)x
A study of this data will reveal several irregularities that requireexplanation. The most significant of these are:
1. Traverse data ci the T53 combustor during the idle runshowed a low fuel-air ratio zone between 300 and 20 degrees.
144
A posttest examination of the fuel manifold showed severalblocked or partially blocked fuel nozzles in the same region.
2. The indicated CO during the first T53 30-percent powerpoint does not appear consistent with previous measurements,although the fluctuations appear to be similar to the fluctua-tions of other components. Instrument malfunction issuspected. This traverse was repeated. A second set ofdata shown is more reasonable.
3. NOx data for several runs are not as precise as might bedesired. Interference of other gaseous components with thepolarographic sensor is a suggested cause.
145
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157
APPENDIX IIT53 ENGINE ISOPLETH EXHAUST CONTOUR PLOTS
The engine exhaust gas sampling traverse was made with the single-point probe to determine CO, HC, CO , NO, and NO at four powerconditions, including idle, 30, 60, an 100 percent of full power.With center-point repetition, 71 data points were recorded. Fromthese data, calculations were made for F/A and combustion efficiency.In order to plot the isopleth concentration (or combustion efficiency)lines, all values were normalized to an average reference value atthe duct center. This reduces any time variation of the concentrationsto a very small amount. Plotted for each power setting are isoplethsfor CO, HC, NO, NO , fuel-air ratio, and combustion efficiency.See Figures 112 through 135.
158
100' 15.
o 0 0
0 0 0 2
0 S/
0 0
1590
750 8 so, 15
10
1600*
00 If
0 0 000 0 0 0
00
00
00
00
0 0 0
0 00
Iss'
Figure 114. T53 Engine Isopleth of NO~ (ppm)at Idle Power.
160
135 4t4 131 7o 0 0 0/
120*
0 0 0 0 0 00 0
*0 00
105075'75.
0
E0* 0
7S' 5$
00 0
0 0 00
'4 0
Ca
Figure 1 1. T53 Engine Isopleth of Fue-rutoEfficin at Idle Power.
161 Is
0 00
0G- 00 0 -1 0 000
0 0 0
0 1000 0
000 0S
71-l.s
0 0
00 0 0 10
0 0 0o 0 A 0
ISO*
s O. IO 1
Figure 11. T3 Engine Isopleth of HO (ppm)at 30% Power.
1 01
00
0 0 0
0 0
0 0~
134
16S.IS
~0*
0/U
Fig 0r 022 05 nieIolt fFe-i
/0S 0C.
U7.
Figue 13. 53 ngie Ispleh o ConbutioEffiienc at 0% Pwer
so'- 0 0.0 0 0 . 1 64 0 0 o
120 0 0 o(0 0 \
00
0
10- 00 0 00 I o -o
I' 0000 0 0 0 a So* 0 -
0 000
00
Ila
o 00 0
0
Is0 0.110 0
Figur~e 1254. T53 Engine Isopleth of C (ppni)at 60% Power.
1165
0 0 0
0 0 0 0
00 0 0
0 0 105-
of NO0pi07 T5 0nin 0a1~
Fig0r -1IN a0% Pow2r.0 0.
Figure 12. T53 Engine Isopleth of NO~ (ppm)at 60% Power.
it166
165. Is.
90 0 00 0 0 -0
kiir 120 Z8 05 nieIolt fFe-i
90.- 00 0 00 0 090
1670
t 16IS * 30,O* IS
4S
135 0 0
0 /0 0 60,
10"~~ c l0 -
0 0
00 0
00 0
0 0 0 0as. 0 4
0 0 0
4S. 0 Me
4,.
/ S 01" LS
is- Se'
Figure 130. T53 Engine Isopleth of CO (ppm)at 100% Power.
ISO* 018" 00tIS$* * 0
011 0 I
0 0 0i w o0 a• 0 N
• 0 •
36#" 11410
Figure 131. T53 Engine Isopleth of HC (pprnC)r' at 10076 Power,.
168
0 0
1' 6 oo. 0
0 0 0 .
Figur 133 T5 Eni0 0t 0f NO (pW
atIt 120Poer
169
\ISO* 30'
0 0 5
N0 0 0 0 0
0 0 00 0 0 0 .
105,'_0*is
0 0
so_ 0 000 0 0 . 0 0 0 410
0
0
0o 0-0 0 00 0 0 0 0 16
0 0 0
0
Is. 001" 14 5
Figure 1 34. T53 Engine Isopleth of Fuel-AirRatio a.t 100% Power.
Hisl
0
0
Figure 135. T53 Engine luopleth of Combustion
Efficiency at 100%o Power.
170
APPENDIX IIIT55 ENGINE LABORATORY COMBUSTOR RIG TRAVERSE DATA
This appendix presents computer "Calcomp" plots (Figures 136 through147) of all the emission traverse data taken in the T55 combustortest rigs only. Each simulated power condition (idle, 30, 60 and 100percent) is represented by three separate plots:
I. Performance summary plot showing fuel-air ratio, combus-
tion efficiency, and the separate component contribution
to combustion inefficiency
2. Emissions in ppm volume for CO, HC, NO, and NO x
(hydrocarbons are in ppmC)
3. Emission index, in pounds per 1000 pounds of fuel for--each component
Scales for the performance summary plot are constant, but the scalefor each of the emission plots is computer-selected to attain thelargest value on the scale. Traverse position is in degrees fromi
.:th, e rig starting point; the T55 rig starts at 300 degrees. This is% significant in comparing results from the rig with engine data or with
/ rig te,perature traverses which start at top dead-center. Symbolson the plots have the following meaning:
* Net cornbustor efficiency
( Fuel-air ratio
* CO (inefficiency, emission index or ppm)
Y HC (inefficiency, emission index, or ppmC)
X NO (emission index or ppm)
X NO (emission index or ppm)
A study of this data will reveal several irregularities that requiresxplanation. The most significant of these are:
1. During the T55 idle traverse, a valve in the sample line
171
was left open for Z0 of the 60 traverse points. As a result,the absolute concentrations for the central 1/3 of the traverseare low by approximately 60 percent.
Z. During the T55 30-percent traverse, the NO instrumentmalfunctioned, and no data are reported. x
3. NO data for several runs are not as precise as might bedesired. Interference of other gasecus components with thepolarographic sensor is a suggested cause.
172
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ti
APPENDIX IVT55 ENGINE ISOPLETH EXHAUST CONTOUR PLOTS
Engine exhaust gas sample traverses were made with the single-pointprobe to determine CO, HC, CO , NO, and NO at four powerconditions, including idle, 30, 66, and 100 perxent of full power.The traverses were completed on one-half of the exhaust, reoriented,and then the second half finished. Including a repeat of the dividing-line diameter between halves and repeats of the centerpoint, 80 datapoints were recorded per traverse. From these data, calculationswere completed for F/A and combustion efficiency, by use of theequations in this report.
In order to plot the isopleth concentrat.on (or combustion efficiency)lines, all values were normalized to an average reference value at
the exhaust duct centerpoint. This reduces any time variation ofthe concentrations to a very small amount. Plotted for each powersetting are isopleths for CO, CH, NO, NO , fuel-air ratio, andcombustion efficiency. See Figures 148 through 171.
*I "
-* 185
N. •
-v
1500 30-
64013S# 4SO
0 0
120* 0 'to0 0 0
0
0 600 0 0SSO 7S*
00 0
0so*- - car - 90*
0 05SO a I
Jo% 560 -- lose0
0 C-01 100 0 0
60* 1200
0 0135*
34*
Is 40/1100 1650
Figure 148. T55 Engine Isopleth of CO (ppm)at Idle Power.
lea Go
133*
300
00 00
0 0 0 .00
0 0
0 0 0
0 0
Lose
0 0 0 0
0 %11A
00
13S*
36*
Is
Figure 149. TSS En&ine Isopleth of HC (ppmC)at idle Power.
186
0 00
60* 0
0 0)
0 IS
3 ISO*
Figure 150. T55 Engine Isopleth of NO (ppm)at Idle Power.
J 187
1'35'
\ , b N
135 0 450 0 0
120# 0 600 0 0
-~~ 90#q -
,s 0 0 0 0
0
05 065
Figure 15. T55 Engine opleth of Foubl-AioRaiinc a t Idle Power.
188/0
los
30*
0 0 0 0 0 so-
- 0 0
90 a) 0 0 0 0 0 .0
~0*
at 3 0 Powert
to / 0 0 I,
45/
I **
Figure 15. T55 Engine Isopleth o C (ppmn)at 30% Power.V 189
N0
0
0 8 /0
0
0 A I @ S1 * 0* 0 0 0 0 o 0 5
0 0 0 0C 0
0 aE 0 C ;2) a'
0000 0 0 00 U0 0
0* IMI
Figure 156. T55 Engine Isopleth of NO (ppm)at 30%6 Power.
0 0 01
W-1 0 00 0:00.
40 0
190
05 \ 0 .
~ 0 .0 0' /
0 00 0
Los--, 0 0 00 'p.7
90- 0o 00- 0 -
105 0 40 0 0
Figure 1 58. T55 Engine Isopleth of Fup-1-AirRatio at,30% -Powpxr.
ISO* 3#*
ft..
W 0
asto
Figure 159. T56 Engine Isopleth of Combustion
Efficiency at 30%6 Pow.er.
191
035 0 4S.
I 01- I
00
0 0 0 0
0 0 )
so$o0 00
0 0 0
let 0 c a
00-0
0 0 35
Figure 16. T55 Engine sopleth of C (pprnC)at 60% PowerDrn nOlSa
Failure.
19'15
iao/o1W
165* is
ato 60%Po0
0
Fig-ire 16. T55 Engne Isopleth of O (ppm)at 60% Powr.
193
0 0
ISO* 30*
0 0 0
0 000 0
OP 0
0 0 0
OS' 115'
Figure 164. T55 Engine Isopleth of NO x(ppm)
at 60% Power.
.0163301
000 0 0
50-0 00 -0 00 '
0 0 0
0 0
0 0
Figure 165. T55 Engine Isopleth of Fuel-AirRatio at 6016 Power.
194
ISO-0 30-
*00
0 0
US % 0 0
105- 0 0 @000 -e
0
00 0 '13
00
00 0 C0 0 04500 03
Figure 16 T55 Engine lIopleth of Comb(pp i)Efiiec a00 Power. wer
15
"1 0-
035 4
90 0 -0 0 00 Ile
030
at- 100 7o5er
75e*
Se- ~ 0 0 0 0 *
Fgre 16. T55 Engine Iopleth of NO (ppm)at 100%4 Power.
150, 196
13S 450V2
-2 .000
0
135. 0 4 .
0 -0 0 000
00
126*
Figure 170. T55 Engine Isopleth of Fuel-AirRatio at 100% Power.
30.
9911
06
0 0
*
