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CAVCAV--Workshop 2010Workshop 2010
DLR DLR –– German Aerospace Research Center German Aerospace Research Center
Aeronautics Space Space Agency Transport Energy
Institute of Propulsion TechnologyInstitute of Propulsion TechnologyEngine Acoustics Division (Berlin)Engine Acoustics Division (Berlin)
Robert Meyer, Lars Enghardt
Hot-wire measurements of a Counter Rotating Turbo Fan (CRTF)
2/19
• DLR and the Department of Engine acoustics
• Hot-wire measurements in Counter Rotating Turbo Fan Rig (CRTF)
OutlineOutline
3/19
DLR DLR –– Sites and EmployeesSites and Employees
� Köln -Porz
� Lampoldshausen
� Stuttgart
� Oberpfaffenhofen
Braunschweig �
� Göttingen
Berlin- - �Adlershof
� Bonn
Trauen �
� Hamburg
� Neustrelitz
Weilheim �
Berlin-Charlottenburg �
� Sankt Augustin
� Darmstadt
Bremen �
Engine AcousticsDivision
6.500 employees working in 29 research institutes and facilities
���� at 9 sites
���� in 7 field offices.
Offices in Brussels, Paris and Washington.
Sites of the Institute of Propulsion Technologies
4/19
MissionMission
DLR Institute of Propulsion Technology
� Increase in efficiency(resource management and reduction of operational costs)
� Minimization of environmental impact(pollutant and noise emission)
� Acceleration of product development cycles
Rolls-Royce TRENT 500 Siemens Power Generation V94.3A
5/19
Organization of the Institute
Institut für AntriebstechnikProf. Dr.-Ing. Reinhard Mönig
Komponenten Querschnittsfunktionen
Fan und VerdichterDr.-Ing. Eberhard Nicke
Fan und VerdichterDr.-Ing. Eberhard Nicke
BrennkammerDr.-Ing. Christoph Hassa
BrennkammerDr.-Ing. Christoph Hassa
TurbineDr.-Ing. Peter-Anton Gieß (komm.)
TurbineDr.-Ing. Peter-Anton Gieß (komm.)
BrennkammertestDipl.-Ing. Christian Fleing
BrennkammertestDipl.-Ing. Christian Fleing
TriebwerksakustikDr.-Ing. Lars Enghardt (komm.)
TriebwerksakustikDr.-Ing. Lars Enghardt (komm.)
TriebwerksmesstechnikDr.-Ing. Christian Willert
TriebwerksmesstechnikDr.-Ing. Christian Willert
Numerische MethodenDr.-Ing. Dirk Nürnberger
Numerische MethodenDr.-Ing. Dirk Nürnberger
TriebwerkDr.-Ing. Andreas Döpelheuer
TriebwerkDr.-Ing. Andreas Döpelheuer
Zentrum für Verbrennungstechnik
Institute of Propulsion Technology (AT)Prof. Dr.-Ing. Reinhard Mönig
Components Cross-sectional tasks
Fan und VerdichterDr.-Ing. Eberhard Nicke
Fan and CompressorDr.-Ing. Eberhard Nicke
BrennkammerDr.-Ing. Christoph Hassa
CombustorDr.-Ing. Christoph Hassa
TurbineDr.-Ing. Peter-Anton Gieß (komm.)
TurbineProf. Dr.-Ing. Ingo Röhle
BrennkammertestDipl.-Ing. Christian Fleing
Combustor TestDipl.-Ing. Christian Fleing
TriebwerksakustikDr.-Ing. Lars Enghardt (komm.)
Engine AcousticsProf. Dr. rer. nat. Lars Enghardt
TriebwerksmesstechnikDr.-Ing. Christian Willert
Engine Measurement SystemDr.-Ing. Christian Willert
Numerische MethodenDr.-Ing. Dirk Nürnberger
Numerical Methods
TriebwerkDr.-Ing. Andreas Döpelheuer
EngineDr.-Ing. Andreas Döpelheuer
Center for Combustor Technology
Dr.-Ing. Edmund Kügeler
6/19
Main Work Topics/ Structure of the Department of Engine Acoustics in Berlin
Infrastructure, Consulting: 8 Employees Overall: 29 Employees
TurbomaschineryAcoustics
Acoustic Data- and Mode analysis
Source localisation
Indoor-, Inflight- und Flyover-Measurements
Jet Noise
Active Noise Control
7 Researcher
U. Tapken/ H. Siller
Lead: Lars Enghardt
Combustion Noise
Combustor sound fields
Optical measurement technique
Entropie- and vortex noise
Liner (hot and cold)
Combustor instabilities
6 Researcher
F. Bake
Active/Passive Flow Control
Turbulence research
Hot wire measurements
Secondary flows
Drag reduction
Efficiency improvements
Compressor flows
3 ResearcherR. Meyer
Numerics/ Modelling
Numerical Acoustic and Software Development (CAA)
Source modellingand directivity
Design to noise
5 Researcher
S. Guerin
• Located on campus of the Technical University of Berlin (TU-Berlin) since 1956,• Staff: 29 (22 Scientists) plus students• More than 50% of personal supported by external funding• Very close cooperation with the
Institute of Fluid Mechanics and Technical Acoustics of TU-Berlin
7/19
Main Strategic DirectionDepartment of Engine Acoustics
� Important role (acoustic competence) in the development of system competence for aero-engines and gas turbines
� Support of research and development activities in turbo-machine acoustic with TRACE
� Cooperation with nacelle aerodynamics to predict and consider acousticalintegration effects (system competence)
� Enhanced integration of research and development activities with other DLR-Institutes (especially Aerodynamics and Flow Technology and Atmospheric Physics)
� Strategic alliances with national and international universities
� Strategic alliances with selected industrial partners and enhanced cooperation with respect to Design-to-Noise in industrial R&D programs
8/19
• Collaborative research Project VITAL “Environmentally Friendly Aero Engines“; 53 Partners gathering all major European engine manufacturersand national research institutes.
• Aim: Reduction of Aircraft noise and CO2 emission• The aero-acoustic performance of three fan module c oncepts was tested in
sub project 2 (Direct Driven Turbo Fan, Geared Turbo Fan and the Counter Rotating Turbo FAN)
• DLR Project Task: Measurements of the unsteady flow field at the inter-stage section of a Counter Rotating Turbo Fan (CRTF) of a fast rotating compressors.
• Two fans rotating in opposite directions, allowing even lower rotation speeds, since the two fans split the loads involved.
• Hot-wire test have been performed on high speed 1/4-scale CRTF model
European Community research program VITAL
9/19
• Main challenging aspects:– 3D velocity field– Unsteady flow structures– Highly fluctuating velocities
(periodic & stochastic fluctuations)
• Benefit:– Verification of the successful design
of new compressor concepts.
– Validation of the numeric flow calculation code (CFD) andnumerical acoustic simulation (CAA)
– Database for the numerical acousticsto improve the models for coupling acoustics and aerodynamics(modeling & prediction group)
Hot-wire measurements of a Counter Rotating Turbo Fan (CRTF)
0 50 100 150 200 250 300 35085
90
95
100
105
110
115
120
125
Rotorumfangsposition [°]
Ges
chw
indi
gkei
t [m
/s]
resampelte machinenkoordinaten54per_3probe_081113_7_U21
time signal
mean average
Fan 1Fan 2
HW 1 HW 2+3 HW 4
u
v
w
Hot-wires
10/19
→ E² =A+B*Un with n≈0.5
Sensor wires: ● platinum-plated tungsten
wires with a diameter of d = 9-12 µµµµm
● wire lengths l =2.4 mm● wire heated during operation
to constant temperature (resistance).
● overheat factor: = 1.8(∆T ≅ 210 K).
● frequency range: f = 0 - 20 kHz.
Velocity U
Current I
Sensor (thin wire)
Sensor dimensions:length ~1 mmdiameter ~5 micrometer
Wire supports (St.St. needles)
Electric current
Principles of the hot-wire technique
Flow velocity U cooling
Wire voltage E
wire temperaturewire
electric resistance
11/19
2X-probecorrelation
Calculation of effective velocities
Analysis procedures
Calibration Phased locked averaging
Rotor trigger interpretation
Analysis:• Mean velocities (phase averaged)• Turbulence levels• Spectra Analysis
Measured raw data
???? ? ?
0 50 100 150 200 250 300 35085
90
95
100
105
110
115
120
125
Rotorumfangspos ition [°]
Ges
chw
indi
gkei
t [m
/s]
resampelte machinenkoordinaten54per_3probe_081113_7_U21
time signal
mean average
Flow field:•3D velocity field•Highly fluctuating velocities
12/19
Methods of analysis Calculation of mean and fluctuating velocities
0 50 100 150 200 250 300 35085
90
95
100
105
110
115
120
125
Rotorumfangsposition [°]
Ges
chw
indi
gkei
t [m
/s]
0 50 100 150 200 250 300 35085
90
95
100
105
110
115
120
125
Rotorumfangsposition [°]
Ge
sch
win
digk
eit
[m/s
]
Phase-locked averaging(PLA) technique
� Statistical averaging locked on rotor rotations
Methods of analysis:
rotation 1 rotation 2
U(t
) in
[m/s
]
Velocity U(t)
Trigger pulses(1 per ref.))(')()( tutUtU +=
Mean velocity
Fluctuating velocity
Instantaneous velocity
)(tU
Instantaneousvelocity
Mean average
)(tU
13/19
Time averaged circumferential position
DU
/Uci
rc
0.29
0
0.58
0.87Axial U-componentbehind rotor 2
Axial U-componentbehind rotor 1
Radial V-componentbehind rotor 1
Circumferential W-componentbehind rotor 1
Circumferential W-componentbehind rotor 2
Phase locked averaged velocities
HW 1 HW 2+3 HW 4
u
v
wCRTF 1 Results: 54% rotor speed
14/19
0 45 90 135 180 225 270 315 360
Turbulenzgrad--Nominal_54per_3probe_081113_7.bin
Sonde A10 UV
Sonde B06 UWSonde B08 UW
Methods of analysisTurbulence levels
)(
)''(
2
122
22
uwWU
wuTu
+
+⋅=
)(
)''(
2
122
22
uv VU
vuTu
++⋅=
Tuuwbehind Rotor 2
Tuuwbehind Rotor 1
Tuuvbehind Rotor 1
HW 2+3 HW 4
u
v
w
Tur
bule
nce
leve
ls
time
CRTF 1 Results: 54% rotor speed
)(
)''(
2
122
22
uwWU
wuTu
+
+⋅=
∆3%
15/19
Methods of analysis Spectral Analysis:
Probe position: Axial: between two Rotors, Radial: 10 mm from outer casingSpectrum is influenced by wall boundary layer
Probe position: Axial: between two Rotors, Radial: 86 mm from outer casingSpectrum is influenced by core flow
Power spectral density Power spectral density
HW 2
u
v
w
HW 2
u
v
w
frequencyfrequency
CRTF 1 Results: 54% rotor speed
1. B
PFR
1
1. BPFR2probe vibration
10. B
PFR
1
16/19
Flow between rotor 1 and rotor 2Axial mean flow velocity U
U component correlated with rotor 1
U component correlated with rotor 2 - Upstream influence
HW 2+3
u
v
w
CRTF 1 Results: 54% rotor speed
DU
/U
cir
c= 0
.145
DU
/U
circ=0
.014
5
17/19
Radial flow velocity V
Flow between rotor 1 and rotor 2 Radial (V) and circumferential (W) velocity (correlated with rotor 1)
Circumferential velocity W
∆W
/U_c
irc=0
182
HW 2+3
u
v
w
CRTF 1 Results: 54% rotor speed
DV
/Ucir
c =
0.0
72
18/19
• In the counter rotating turbo fan hot-wire probes were placed in front of the first rotor, between both rotors and behind the second rotor. The measurements were conducted at three operating conditions ofthe compressor fan stage, relevant to noise issues (approach, takeoff/sideline and takeoff/cutback).
• With the DLR hot-wire measuring technique, unsteady flow structures of fast rotating compressors (e.g. the wake of each individual rotor blade) can be measured and analyzed in detail. The averaged mean vectors as well as the fluctuation components of the velocity are determined, which allows the local turbulencedistribution of the flow behind the rotating blades to be calculated.
• These hotwire data results verify on the one hand the successful design of the new compressor concepts and offer on the other hand valuable information for the validation of the numerical flow-calculation code (CFD) to be applied.
• In addition, the results deliver a valuable data base for the development and future use of numerical acoustic simulation (CAA) tools, in particular to improve models for coupling acoustics and aerodynamics. In future, this will enable an improved noise and efficiency prediction already in the early stage of the fan modules design process.
SummarySummary
19/19
Thank you for your attentionThank you for your attention
Questions …?Questions …?
E-mail: [email protected] to the project will be published on the ASM E-Conference 2010
Paper: GT2010-22569
The project is supported by the European Community within the Research Program “Environmentally Friendly Aero Engines (VITAL)“