simulation of a-pillar/side glass flows for bluff suv geometries
DESCRIPTION
Report of first stages of methods development for aeroacoustic simulation using CFD (PowerFLOW). Published as: Gaylard AP (2004) Simulation of A-Pillar/Side Glass Flows For Bluff SUV Geometries. In, Fifth MIRA International Conference On Vehicle Aerodynamics, 13-14 October 2004, Heritage Motor Centre, Gaydon, UKTRANSCRIPT
1
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
5th MIRA International
Vehicle Aerodynamics Conference
13-14 October 2004
Heritage Motor Centre
Warwick UK
Simulation of A-Pillar/Side Glass Flows For Bluff SUV
GeometriesAdrian Gaylard
Aerodynamics
Jaguar and Land Rover
2
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Introduction
Background
Simulations
Results
Conclusions
Contents
3
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Introduction
Forces and Moments
Potential applications of CFD
4
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Thermal Management
Introduction Potential applications of CFD
5
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Brake Cooling
Introduction Potential applications of CFD
6
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Introduction
Soiling
Potential applications of CFD
7
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Water Management
Introduction Potential applications of CFD
8
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Why focus on A-Pillar /Side Glass?
Introduction Potential applications of CFD
9
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Windscreen
Accelerated (attached) flow on the roof
Rotating vortex
Reattachment line
Attached flow region
Separated flow region
A-pillar
A-Pillar Flow Structure (after Haruna et al)
Background
10
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Bluff SUV
Background
11
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
CFD Technique
Exa PowerFLOW™
Tends to over-predict A-pillar vortex strength and size
RANS methods tend to under-predict A-pillar vortex strength and size (Murad et al)
Background
12
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Simulation Parameters
Simulations
No. Elements /106
ID Simulation Type
Turbulence Model*
Boundary Layer Length Scale† Voxels Surfels
Inlet Velocity U / ms-1
A Low-resolution Dissipative Standard 18.6 1.62 35.0 B Aerodynamic Dissipative Standard 26.7 1.70 27.8 C Aeroacoustic Unsteady Standard 19.4 1.34 27.8 D Aeroacoustic Unsteady Standard 22.3 1.45 36.1 E Aerodynamic Unsteady Local 20.7 1.79 27.8 F Aeroacoustic Unsteady Local 24.5 1.70 36.1 G Aerodynamic Unsteady Local 18.2 1.39 27.8
Mesh Structure
13
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Simulation Parameters
Simulations
No. Elements /106
ID Simulation Type
Turbulence Model*
Boundary Layer Length Scale† Voxels Surfels
Inlet Velocity U / ms-1
A Low-resolution Dissipative Standard 18.6 1.62 35.0 B Aerodynamic Dissipative Standard 26.7 1.70 27.8 C Aeroacoustic Unsteady Standard 19.4 1.34 27.8 D Aeroacoustic Unsteady Standard 22.3 1.45 36.1 E Aerodynamic Unsteady Local 20.7 1.79 27.8 F Aeroacoustic Unsteady Local 24.5 1.70 36.1 G Aerodynamic Unsteady Local 18.2 1.39 27.8
Turbulence Model
14
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Simulation Parameters
Simulations
No. Elements /106
ID Simulation Type
Turbulence Model*
Boundary Layer Length Scale† Voxels Surfels
Inlet Velocity U / ms-1
A Low-resolution Dissipative Standard 18.6 1.62 35.0 B Aerodynamic Dissipative Standard 26.7 1.70 27.8 C Aeroacoustic Unsteady Standard 19.4 1.34 27.8 D Aeroacoustic Unsteady Standard 22.3 1.45 36.1 E Aerodynamic Unsteady Local 20.7 1.79 27.8 F Aeroacoustic Unsteady Local 24.5 1.70 36.1 G Aerodynamic Unsteady Local 18.2 1.39 27.8
Boundary Layer
15
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Mesh Structure and Resolution
Simulations
Low Resolution
10-12
mm
5-6 mm
16
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Mesh Structure and Resolution
Simulations
Aerodynamics
10-12
mm
5-6 mm
2.5-3
mm
17
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Mesh Structure and Resolution
Simulations
Aeroacoustics
10-12
mm
5-6 mm
2.5-3
mm
1.5 mm
18
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Surface Flow Visualisation
Results
WT
Low Res. Aeroacoustic Aerodynamic
A
5 mm
E
2.75 mm
D
1.5 mm
19
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Surface Static Pressure
Results
Low Res. Aeroacoustic Aerodynamic
A
D
E
WT
20
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Surface Static Pressures
Results
Side Window Static Pressures, Row 6
-1.200
-1.000
-0.800
-0.600
-0.400
-0.200
0.000
0.200
900 1100 1300 1500
Longitudinal Distance Downstream X /mm
Su
rfac
e S
tati
c P
ress
ure
Co
effi
cien
t, C
p
MIRA FSWT A B C D E F G
Side Window Static Pressures, Row 6
-1.200
-1.000
-0.800
-0.600
-0.400
-0.200
0.000
0.200
900 1000 1100 1200 1300 1400 1500 1600
Longitudinal Distance Downstream X /mm
Su
rfac
e S
tati
c P
ress
ure
Co
effi
cie
nt,
Cp
21
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Surface Static Pressures
Results
Side Window Static Pressures, Row 6
-1.200
-1.000
-0.800
-0.600
-0.400
-0.200
0.000
0.200
900 1100 1300 1500
Longitudinal Distance Downstream X /mm
Su
rfac
e S
tati
c P
ress
ure
Co
effi
cien
t, C
p
MIRA FSWT A B C D E F G
Side Window Static Pressures, Row 5
-1.200
-1.000
-0.800
-0.600
-0.400
-0.200
0.000
0.200
900 1000 1100 1200 1300 1400 1500 1600
Longitudinal Distance Downstream X /mm
Su
rfac
e S
tati
c P
ress
ure
Co
effi
cie
nt,
Cp
22
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Surface Static Pressures
Results
Side Window Static Pressures, Row 6
-1.200
-1.000
-0.800
-0.600
-0.400
-0.200
0.000
0.200
900 1100 1300 1500
Longitudinal Distance Downstream X /mm
Su
rfac
e S
tati
c P
ress
ure
Co
effi
cien
t, C
p
MIRA FSWT A B C D E F G
Side Window Static Pressures, Row 4
-1.200
-1.000
-0.800
-0.600
-0.400
-0.200
0.000
0.200
900 1000 1100 1200 1300 1400 1500 1600
Longitudinal Distance Downstream X /mm
Su
rfac
e S
tati
c P
res
sure
Co
eff
icie
nt,
Cp
23
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Surface Static Pressures
Results
Side Window Static Pressures, Row 6
-1.200
-1.000
-0.800
-0.600
-0.400
-0.200
0.000
0.200
900 1100 1300 1500
Longitudinal Distance Downstream X /mm
Su
rfac
e S
tati
c P
ress
ure
Co
effi
cien
t, C
p
MIRA FSWT A B C D E F G
Side Window Static Pressures, Row 3
-1.200
-1.000
-0.800
-0.600
-0.400
-0.200
0.000
0.200
900 1000 1100 1200 1300 1400 1500 1600
Longitudinal Distance Downstream X /mm
Su
rfac
e S
tati
c P
ress
ure
Co
effi
cie
nt,
Cp
24
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Side Window Static Pressures, Row 2
-1.200
-1.000
-0.800
-0.600
-0.400
-0.200
0.000
0.200
900 1000 1100 1200 1300 1400 1500 1600
Longitudinal Distance Downstream X /mm
Su
rfa
ce S
tati
c P
res
sure
Co
eff
icie
nt,
Cp
Surface Static Pressures
Results
Side Window Static Pressures, Row 6
-1.200
-1.000
-0.800
-0.600
-0.400
-0.200
0.000
0.200
900 1100 1300 1500
Longitudinal Distance Downstream X /mm
Su
rfac
e S
tati
c P
ress
ure
Co
effi
cien
t, C
p
MIRA FSWT A B C D E F G
25
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Surface Static Pressures
Results
Side Window Static Pressures, Row 1
-1.200
-1.000
-0.800
-0.600
-0.400
-0.200
0.000
0.200
900 1000 1100 1200 1300 1400 1500 1600
Longitudinal Distance Downstream X /mm
Su
rfac
e S
tati
c P
ress
ure
Co
eff
icie
nt,
Cp
Side Window Static Pressures, Row 6
-1.200
-1.000
-0.800
-0.600
-0.400
-0.200
0.000
0.200
900 1100 1300 1500
Longitudinal Distance Downstream X /mm
Su
rfac
e S
tati
c P
ress
ure
Co
effi
cien
t, C
p
MIRA FSWT A B C D E F G
26
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Near-Surface Velocity Profiles
Results
Position #1
0
10
20
30
40
50
60
70
80
0 0.2 0.4 0.6 0.8 1 1.2
u/U
h/m
m
Low Resolution simulation (A)
Aeroacoustic simulation (D)
Experiment
27
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Position #2
0
10
20
30
40
50
60
70
80
0 0.2 0.4 0.6 0.8 1 1.2
u/U
h/m
m
Near-Surface Velocity Profiles
Results
Low Resolution simulation (A)
Aeroacoustic simulation (D)
Experiment
28
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Position #3
01020304050607080
0 0.2 0.4 0.6 0.8 1 1.2
u/U
h/m
m
Near-Surface Velocity Profiles
Results
Low Resolution simulation (A)
Aeroacoustic simulation (D)
Experiment
29
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Position #4
01020304050607080
0 0.2 0.4 0.6 0.8 1 1.2
u/U
h/m
m
Near-Surface Velocity Profiles
Results
Low Resolution simulation (A)
Aeroacoustic simulation (D)
Experiment
30
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Position #5
01020304050607080
0 0.2 0.4 0.6 0.8 1 1.2
u/U
h/m
m
Near-Surface Velocity Profiles
Results
Low Resolution simulation (A)
Aeroacoustic simulation (D)
Experiment
31
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Position #6
01020304050607080
0 0.2 0.4 0.6 0.8 1 1.2
u/U
h/m
m
Near-Surface Velocity Profiles
Results
Low Resolution simulation (A)
Aeroacoustic simulation (D)
Experiment
32
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Near-Surface Velocity Profiles
Results
Low Resolution simulation (A)
Aeroacoustic simulation (D)
Experiment
Position #7
01020304050607080
0 0.2 0.4 0.6 0.8 1 1.2
u/U
h/m
m
33
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Near-Surface Velocity Profiles
Results
Low Resolution simulation (A)
Aeroacoustic simulation (D)
Experiment
Position #8
01020304050607080
0 0.2 0.4 0.6 0.8 1 1.2
u/U
h/m
m
34
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Near-Surface Velocity Profiles
Results
Low Resolution simulation (A)
Aeroacoustic simulation (D)
Experiment
Position #9
01020304050607080
0.000 0.200 0.400 0.600 0.800 1.000 1.200
u/U
h/m
m
35
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Near-Surface Velocity Profiles
Results
Low Resolution simulation (A)
Aeroacoustic simulation (D)
Experiment
Position #10
01020304050607080
0 0.2 0.4 0.6 0.8 1 1.2
u/U
h/m
m
36
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Near-Surface Velocity Profiles
Results
Low Resolution simulation (A)
Aeroacoustic simulation (D)
Experiment
Position #11
01020304050607080
0 0.2 0.4 0.6 0.8 1 1.2
u/U
h/m
m
37
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Near-Surface Velocity Profiles
Results
Low Resolution simulation (A)
Aeroacoustic simulation (D)
Experiment
Position #12
01020304050607080
0.000 0.200 0.400 0.600 0.800 1.000 1.200
u/U
h/m
m
38
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Near-Surface Velocity Profiles
Results
Low Resolution simulation (A)
Aeroacoustic simulation (D)
Experiment
Position #13
01020304050607080
0 0.2 0.4 0.6 0.8 1 1.2
u/U
h/m
m
39
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Near-Surface Velocity Profiles
Results
Low Resolution simulation (A)
Aeroacoustic simulation (D)
Experiment
Position #14
01020304050607080
0 0.2 0.4 0.6 0.8 1 1.2
u/U
h/m
m
40
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Surface Noise Spectra
Results
20
30
40
50
60
70
80
90
100
110
120
16 31.5 63 125 250 500 1000 2000 4000
Frequency (3rd Octave) /Hz
SP
L /d
B(A
)
Simulation D
AWT
41
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Surface Noise Spectra
Results
20
30
40
50
60
70
80
90
100
110
120
16 31.5 63 125 250 500 1000 2000 4000
Frequency (3rd Octave) /Hz
SP
L /d
B(A
)
42
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Surface Noise Spectra
Results
20
30
40
50
60
70
80
90
100
110
120
16 31.5 63 125 250 500 1000 2000 4000
Frequency (3rd Octave) /Hz
SP
L /d
B(A
)
43
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Surface Noise Spectra
Results
20
30
40
50
60
70
80
90
100
110
120
16 31.5 63 125 250 500 1000 2000 4000
Frequency (3rd Octave) /Hz
SP
L /d
B(A
)
44
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Surface Noise Spectra
Results
20
30
40
50
60
70
80
90
100
110
120
16 31.5 63 125 250 500 1000 2000 4000
Frequency (3rd Octave) /Hz
SP
L /d
B(A
)
45
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Surface Noise Spectra
Results
20
30
40
50
60
70
80
90
100
110
120
16 31.5 63 125 250 500 1000 2000 4000
Frequency (3rd Octave) /Hz
SP
L /d
B(A
)
46
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Surface Noise Spectra
Results
20
30
40
50
60
70
80
90
100
110
120
16 31.5 63 125 250 500 1000 2000 4000
Frequency (3rd Octave) /Hz
SP
L /d
B(A
)
47
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
20
30
40
50
60
70
80
90
100
110
120
16 31.5 63 125 250 500 1000 2000 4000
Frequency (3rd Octave) /Hz
SP
L /d
B(A
)
Surface Noise Spectra
Results
48
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Simulation Accuracy
An adequate simulation of the side glass flow structure.
PSDavg(CFD-Exp.) = –1.8dB(A) 6Hz to 250Hz
= –3.8dB(A) 315Hz to 4kHz
CP = 0.13
over-predicted:
Negative static pressures induced by the A-pillar vortex
Flow past the inside edge of the door mirror
Conclusions I
49
A-Pillar/Side Glass Flows for Bluff SUVs Adrian Gaylard
Sensitivities
spatial resolution
characteristics of the turbulence model
boundary layer length scale
Conclusions II