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Aerodynamics and CFD at Aerodynamics and CFD at Aerodynamics and CFD at Aerodynamics and CFD at
Volvo Car CorporationVolvo Car CorporationVolvo Car CorporationVolvo Car Corporation
KTH April 2012
Johan Ljungberg
Volvo Car Corporation
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agenda
…..
CFD group, Organization, Basic
aerodynamics definitions
Process overview
Influence of aerodynamics
background
Development process
…..
….. Why is aerodynamics important? Review, Challenges facing Aerodynamics
….. Test techniques and methodsfacilities
….. Aerodynamics development of C30 DRIVeDrive project
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Present at the CFD group: 19 employees
Graduated from KTH 2005
Scania AB 2005-2006
Volvo Cars 2006-
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VCC Environmental & Fluid Dynamics Centre
Product Development
Complete Vehicle
Environmental and
Fluid Dynamics Centre
Fuel Economy Weight/MOC Thermo Aero/Contamination CFD
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Aerodynamics definitions
D = ½ x ρ x v2 x Cd x A
D is the force of drag, which is by defention the force component in the
direction of the flow velocity
ρ is the mass density of the fluid
v is the velocity of the object relative to the fluid
A is the frontal area
Cd is the dimensionless drag coefficient, related to the object´s shape
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Drag (fuel consumption, top speed, acceleration)
High-speed stability (lift)
Cross-wind stability (side force and yawing moment)
Passenger comfort (cabriolets)
Cooling Performance
Dirt deposition (visibility)
Aero acoustics (limiting the strength of sources)
Body deformation (Door frames etc)
Influence of Aerodynamics
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45%
30%
25%
Influence of Aerodynamics
Sources of drag on a modern car
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Aerodynamics part of total fuel consumption
”EU Combined cycle” NEDC
(Note! Average speed ≈33km/h)
Transmission losses
8%Electrical
systems
16%
Drag
26%
Rolling
resistance
21%
Lost kinematic energy
during braking
29%
Influence of Aerodynamics
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Aerodynamics part of total fuel consumption
Influence of Aerodynamics
9%8%
53%
30%
Drag
Electrical
systems
Rolling
resistance
Transmission
losses
Constant speed 90 km/h
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Cd v Year
0.25
0.30
0.35
0.40
0.45
0.50
0.55
0.60
1950 1960 1970 1980 1990 2000 2010 2020
Year Cd
PV 544 1955 0,50
Amazon 1960 0,48
P1800 1963 0,48
P1800ES 1968 0,61
240 1974 0,47
245 1975 0,45
343 1979 0,42
760 1982 0,44
765 1985 0,40
960 1990 0,40
854 1992 0,35
855 1993 0,34
S80 1998 0,31
V70 2000 0,33
XC90 2002 0,40
V50 2004 0,35
S40N 2003 0,34
460 1986 0,39
480ES 1985 0,38
S40 1995 0,34
V40 1995 0,36
Influence of Aerodynamics
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Year Cd
PV 544 1955 0,50
Amazon 1960 0,48
P1800 1963 0,48
P1800ES 1968 0,61
240 1974 0,47
245 1975 0,45
343 1979 0,42
760 1982 0,44
765 1985 0,40
960 1990 0,40
854 1992 0,35
855 1993 0,34
S80 1998 0,31
V70 2000 0,33
XC90 2002 0,40
V50 2004 0,35
S40N 2003 0,34
460 1986 0,39
480ES 1985 0,38
S40 1995 0,34
V40 1995 0,36
CdxA v Year
0,60
0,70
0,80
0,90
1,00
1,10
1,20
1950 1960 1970 1980 1990 2000 2010 2020
Influence of Aerodynamics
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Year Cd
PV 544 1955 0,50
Amazon 1960 0,48
P1800 1963 0,48
P1800ES 1968 0,61
240 1974 0,47
245 1975 0,45
343 1979 0,42
760 1982 0,44
765 1985 0,40
960 1990 0,40
854 1992 0,35
855 1993 0,34
S80 1998 0,31
V70 2000 0,33
XC90 2002 0,40
V50 2004 0,35
S40N 2003 0,34
460 1986 0,39
480ES 1985 0,38
S40 1995 0,34
V40 1995 0,36
Frontal Area v Year
1,50
1,70
1,90
2,10
2,30
2,50
2,70
2,90
1950 1970 1990 2010
Influence of Aerodynamics
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Challenges facing Aerodynamicists
Styling
Manufacturing
- Parts
- Assembly
Packaging
Visbility
Other attributes (Thermo, dirt, handling, etc)
”Carry-over” content
Cost
Influence of Aerodynamics
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Drive project
Aerodynamics on the C30 DRIVe
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C30 DRIVe Aerodynamic parts
Cooling air intake
Front wheel deflectorsFront undershield
Drive project
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Roof wing
Rear bumper
Diffusor panel Floor panels
Cover plate
Drive project
C30 DRIVe Aerodynamic parts
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∆Cd -0.002
∆Cd -0.002
∆Cd -0.012
Drive project
C30 DRIVe Drag reduction
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Special wheels - Libra
∆Cd -0.005 (compared to steel rims)
Lowered chassis
∆Cd -0.005
Drive project
C30 DRIVe Aerodynamic parts
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Aerodynamic drag reduced more than 10% compared to standard car
Fuel consumption reduced by:
• 0,12 l/100km or 3g CO2/km (EU Combined)
- (this corresponds to an equivalent weight reduction of approx. 80kg)
• 0,3 l/100km @ constant 90km/h
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In-house testing in three wind tunnels, Gothenburg
PVT MWT Climatic Test section 27m2 (6.6mx4.1m , length 15.8m)
Max speed 250 kph
Temp. +20 to 60° C Chassi dyn. load 150 kW Sun sim. max 1200 W/m2
1:5 scale of PVT Test section 1.1m
2
Max. speed 200 kph
Test section/nozzle 11.2m2 Max. speed 200 kph
Temp range -40 to +50° C Chassi dyn. load 280 kW Sun sim. max 1200 W/m2
facilities
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Balance measurements
Effect of configuration changes on aero coefficients
Sensitivity to flow angle, vehicle attitude and wind speed
Centre belt
Wheel Drive Units
Supporting
strutsMeasuring
frame
Turn table
facilities
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Why Moving Ground is Neccessary
Influences flow under
and around the car
Provides correct relative movement
between the car body and tunnel floor
Provides correct relative movement
between the car body and wheels
facilities
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Stationary Floor and Wheels
Wind
facilities
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Wind
Road/Floor
facilities
Moving ground and rotating wheels
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Roof and boot
Front-end and deflectors
Underbody design
Wheel Design
facilities
Optimasation affected
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Flow visualization (smoke, surface paint, tufts)
Increase the knowledge gained from aerodynamic testing
facilities
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facilities
Increase the knowledge gained from aerodynamic testing
Preasure measurements
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dydzUPUPD )(2
22
2
11ρρ −−+= ∫∫
Seven-hole probe rake Floor traverse
facilities
Increase the knowledge gained from aerodynamic testing
Wake measurements
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Total pressure Microdrag
Identify regions that can be improved
facilities
Increase the knowledge gained from aerodynamic testing
Wake measurements 100 mm downstream base
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Thank you for your attention!
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Want to jumpstart your career?
Apply to the
Volvo Cars Global
Graduate Programme 2013
start August 2013, application fall 2012
www.volvocars.com/graduate