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Airflow and Fuel Spray Interaction in a Gasoline DI Engine. Professor Morgan Heikal Internal Combustion Engines Group University of Brighton & Ricardo UK Ltd. Presentation outline. Area of Study Test Equipment and Methods Mie scatter studies Backlighting studies CFD analysis - PowerPoint PPT Presentation
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Instituto Brasileirode Petróleo e Gás
UniversityUniversity ofof
BrightonBrighton
Airflow and Fuel Spray Interaction in a Gasoline DI
Engine
Professor Morgan HeikalProfessor Morgan HeikalInternal Combustion Engines GroupInternal Combustion Engines Group
University of BrightonUniversity of Brighton&&
Ricardo UK LtdRicardo UK Ltd
2
Presentation outline
Area of StudyTest Equipment and
Methods• Mie scatter studies • Backlighting studies• CFD analysis
Results evaluationConclusions
3
Area of Study
Airflow and Fuel Spray Interaction• Early injection regimes• Variation of spray characteristics with
injection timing• Distortion of fuel jet by air flow
Comparison of experiment with CFD analysis• To check on experimental findings
4
Test EngineRicardo ‘Hydra’ G-DI research engineSingle-cylinder, wall-guidedFull-quartz optical cylinder linerHeated Piston
throttle
intake plenum
cam box
cam pulleys
cylinder head
exhaust
cylinder liner
timing belt
flywheel
piston head
piston extension
5
Engine Combustion ChamberTop entry, pent roof
construction Injector
• side mounted• swirl atomiser • 70o included angle
Spark Plug• centrally located
2d piston profile75mm stroke74mm bore
New diagram including piston profile and spark plug
Get bette
r image and re
-do layo
ut
Get bette
r image and re
-do layo
ut
6
Optical Methods IMie scatter
• 1000 rev/min, WOT, SOI ATDC 20, 40, 60o
Nd:YAG Lasershuttercontrol
Computer CCD Camera
45o mirror
sheet optics
beam dump
Combustionchamber
Nd:YAG Lasershuttercontrol
Computer CCD Camera
45o mirror
sheet optics
beam dump
Combustionchamber
7
Optical Methods II
Backlighting studies• 1000 rev/min• WOT• SOI
• ATDC 20, 40, 60o
Computer
Combustionchamber
flash lamps
Flash trigger
ImaconHigh Speed Camera
Light diffuser
Computer
CombustionchamberCombustionchamber
flash lamps
Flash trigger
ImaconHigh Speed Camera
Light diffuser
8
CFD AnalysisCFD Code
Ricardo VECTIS Fuel spray model
Discrete droplet model (DDM) Ensemble of droplet parcels Introduction rate given by
injection rate spray angle droplet size distribution
Secondary break-up sub-models Droplet turbulence interaction and impingement Secondary break-up model – Reitz-Diwakar
9
Mie Scatter Results I
(a)
Raw average image
(b)
Thresholded image
Masked image
(c)
10
Mie Scatter Results II
(a) (b) Edge detection
Injection progress
(c)
11
Mie Scatter Results III
6CA 9.6CA
13.2CA 16.8CA
SOI = 20CA ATDC SOI = 20oATDC
SOI = 40A
ATDC SOI = 40oATDC
SOI = 60oATDC
SOI = 60CA ATDC
SOI = 80oATDC
SOI = 80A ATDC
12
Backlighting Results I
Averaged imageintake valves
Edge detectedintake valves
13
Backlighting Results IISpray width intensity profile analysis
30 pixel
60 pixel
90 pixel
30 pixel
60 pixel
90 pixel
14
CFD Analysis Ispray shadow
central planend2
air speedvapour
air speed on valve CL
15
CFD Analysis IIMie Scattering CFD nd2 – 1mm CFD spray chop 1mm CFD whole spray CFD vapour phase CFD velocity J18 CFD velocity J26 CFD velocity J34
24.8o
24.8o
24.8o
24.8o
24.8o
24.8o
24.8o
26.0o
26.0o
26.0o
26.0o
26.0o
26.0o
26.0o
27.2o
27.2o
27.2o
27.2o
27.2o
27.2o
27.2o
28.4o
28.4o
28.4o
28.4o
28.4o
28.4o
28.4o
29.6o
29.6o
29.6o
29.6o
29.6o
29.6o
29.6o
Comparison of results of CFD analysis with experiment
16
CFD Comparison with Experiment
SOI 60o CA8o ASOI
SOI 60o CA21o ASOI
17
0
0.2
0.4
0.6
0.8
1
1.2
0 5 10 15 20 25 30 35Crank Angles ASOI
N
orm
alis
ed
Inte
nsi
ty
0
0.1
0.2
0.3
0.4
0.5
0.6
Fu
el In
jectio
n R
ate
20CA
FuellingRate
SOI EOI
Intensity variation with SOI
0
0.2
0.4
0.6
0.8
1
1.2
0 5 10 15 20 25 30 35Crank Angles ASOI
N
orm
alis
ed
Inte
nsi
ty
0
0.1
0.2
0.3
0.4
0.5
0.6
Fu
el In
jectio
n R
ate
20CA
40CA
FuellingRate
SOI EOI
0
0.2
0.4
0.6
0.8
1
1.2
0 5 10 15 20 25 30 35Crank Angles ASOI
N
orm
alis
ed
Inte
nsi
ty
0
0.1
0.2
0.3
0.4
0.5
0.6
Fu
el In
jectio
n R
ate
20CA
40CA
60CA
FuellingRate
SOI EOI
0
0.2
0.4
0.6
0.8
1
1.2
0 5 10 15 20 25 30 35Crank Angles ASOI
N
orm
alis
ed
Inte
nsi
ty
0
0.1
0.2
0.3
0.4
0.5
0.6
Fu
el In
jectio
n R
ate
20CA
40CA
60CA
80CA
FuellingRate
SOI EOI
Analysis of Mie Scatter Data
18
Backlighting evidenceAverage spray width at 3 depths
•For 1.2, 1.6, 2.0, 2.4, 2.9ms ASOI•Width decreases with later SOI
0
5
10
15
20
25
30 40 50 60 70 80 90SOI
Sp
ray
wid
th (
mm
)
30 pixel
60 pixel
90 pixel
19
0
0.2
0.4
0.6
0.8
1
1.2
0 5 10 15 20 25 30 35Crank Angles ASOI
N
orm
alis
ed
Inte
nsi
ty
20CA
40CA
60CA
80CA
SOI EOI
0
0.2
0.4
0.6
0.8
1
1.2
0 5 10 15 20 25 30 35Crank Angles ASOI
N
orm
alis
ed
Inte
nsi
ty
20CA
40CA
60CA
80CA
SOI EOI
0
0.2
0.4
0.6
0.8
1
1.2
0 5 10 15 20 25 30 35Crank Angles ASOI
N
orm
alis
ed
Inte
nsi
ty
20CA
40CA
60CA
80CA
SOI EOI
Comparison with CFDCFD nd2 values
• Similar increase with SOI• Similar fluctuations CFDMie scatterCFD
20
Intensity Increase with SOI
Central plane intensity onlyJet squeezed by incoming air from valvesPlume shape changed
• Flattened in cross-tumble plane• Broadened in tumble plane
More fuel is maintained in central planeDue to increased valve lift and air flow with later
SOICould have been due to changes in droplet size
• Checked against Begg(2003) and eliminated
21
Intensity Irregularity with SOI
Comes from jet flapping• Seen in
vapour distribution
• Valid indicator for early stages
• Clearest visualisation
22
Measured Jet flapping
Video representation• Jet flap at start• As CFD image• Despite average
image• Rotational
oscillation?• Takes fuel in and
out of central plane
• Explains intensity fluctuation with SOI
23
Backlighting ImageOscillation also seen in this
plane
24
Backlighting ImageOscillation also seen in this
plane
25
ConclusionFor early injection, incoming air acts on fuel jet
• Air flow from two valves flatten jet• Fuel squeezed towards central pane• Effect increases with SOI delay
• Shows as increasing Mie signal coverage and intensity • Due to increasing air flow as valve opening and piston speed increase
• Narrowing seen in other plane • Fuel jet is deflected downwards
Jet is seen to oscillate• Visible from Mie and backlighting data perspective• Manifests as irregularity in Mie signal through injection process
CFD Analysis • Confirms effect if air inflow on jet• Predicts oscillation of jet• Is in general good agreement with experiment
Single plane data can be difficult to interpret
26
Close
Thank you for your attention!Any questions?