aerodynamics and cfd at volvo car corporation · 2012-05-04 · page 1 aerodynamics and cfd at...

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

Page 2

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

Present at the CFD group: 19 employees

Graduated from KTH 2005

Scania AB 2005-2006

Volvo Cars 2006-

Page 4

VCC Environmental & Fluid Dynamics Centre

Product Development

Complete Vehicle

Environmental and

Fluid Dynamics Centre

Fuel Economy Weight/MOC Thermo Aero/Contamination CFD

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

Page 6

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

Page 7

45%

30%

25%


Sources of drag on a modern car

Page 8

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%


Aerodynamics part of total fuel consumption


9%8%

53%

30%

Drag

Electrical

systems

Rolling

resistance

Transmission

losses

Constant speed 90 km/h

Page 10

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


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


Page 12

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


Challenges facing Aerodynamicists

Styling

Manufacturing

- Parts

- Assembly

Packaging

Visbility

Other attributes (Thermo, dirt, handling, etc)

”Carry-over” content

Cost


Page 14

Drive project

Aerodynamics on the C30 DRIVe

C30 DRIVe Aerodynamic parts

Cooling air intake

Front wheel deflectorsFront undershield

Drive project

Page 16

Roof wing

Rear bumper

Diffusor panel Floor panels

Cover plate

Drive project


∆Cd -0.002

∆Cd -0.002

∆Cd -0.012

Drive project

C30 DRIVe Drag reduction

Page 18

Special wheels - Libra

∆Cd -0.005 (compared to steel rims)

Lowered chassis

∆Cd -0.005

Drive project


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

Page 20

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

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

Page 22

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

Stationary Floor and Wheels

Wind

facilities

Page 24

Wind

Road/Floor

facilities

Moving ground and rotating wheels

Roof and boot

Front-end and deflectors

Underbody design

Wheel Design

facilities

Optimasation affected

Page 26Page 26

Flow visualization (smoke, surface paint, tufts)

Increase the knowledge gained from aerodynamic testing

facilities

facilities


Preasure measurements

Page 28

dydzUPUPD )(2

22

2

11ρρ −−+= ∫∫

Seven-hole probe rake Floor traverse

facilities


Wake measurements

Total pressure Microdrag

Identify regions that can be improved

facilities


Wake measurements 100 mm downstream base

Page 30

Thank you for your attention!

Want to jumpstart your career?

Apply to the

Volvo Cars Global

Graduate Programme 2013

start August 2013, application fall 2012

www.volvocars.com/graduate

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