STAR European Conference 2010

AERODYNAMICS DEVELOPMENTS

ON A LE MANS PROTOTYPE

ORECA 01 LMP1

1. ORECA Presentation

2. Why we use CFD?

2009 Aero Development

2010 Aero Development

3. Methodology

Correlation

Case Studies

Mesh

Results

Conclusions

PRESENTATION

ORECA:

Since 1972

180 People

35 to 40 Millions Euros / year

4 divisions:

Engine department (Magny-Cours)

Marketing + Incentive

Race parts + accessories sales

Race team + Chassis Engineering

1. ORECA

ORECA:

RACE TEAM:

Endurance Racing (LMP1 – 2 cars)

Audi R8 GT3 (French GT – 2 cars)

Formula Le Mans

Other projects (engineering / production)

Engineering:

11 Engineers

Aero-group : 6 engineers, 4 working on Star-CCM+

1. ORECA

2009 CFD Development

We used CFD for :

- Comprehension of LMP aerodynamics- Keep the development of aero-package up through the season

We chose Star-CCM+ for :

- Only one interface- Ratio simplicity / accuracy / cost- Evolution of the Software through the year

2. Why we use CFD?

2009 Aerodynamic Development:

Oreca 01 :

• Adapt to new ACO Aerodynamics rules (reduction of the rear wing dimensions)

• New aero-package for Courage LC70E LMP1

Tests : ~80% Wind tunnel, ~20% CFD

• 320 runs using a 40% scale model in ACE wind-tunnel (Magny-Cours).

• CFD development : 1 engineer (1 Workstation) working on Star-CCM+ / +80 simu.

2. Why we use CFD?

2009 CFD Development

History

ORECA 01 V1: introduced in 1000 km Spa (May 2009)

ORECA 01 V2: introduced in 1000 km Silverstone (Sept. 2009). Developped 100% using CFD.

Increasing Efficiency and Downforce

95

97.5

100

102.5

105

107.5

110

112.5

115

2008 car 2008 car +

2009 wing

ORECA 01

V1

ORECA 01

V2

Efficiency

2. Why we use CFD?

2. Why we use CFD?

2. Why we use CFD?

1,5

0,082

-0,141

-0,916

-1

0

1

2

3

4

5

6

7

Race1 Barcelone Race2 Spa Race3 Algarve Race5 Silverstone

Qualifying performances Le Mans Serie 2009

ORECA 01 Position

Aston Position

2. Why we use CFD?

2010 Aerodynamic Development:

Oreca 02 :

• New LMP1 car designed to compete for 24H of Le Mans (2011) with Peugeot Engine

Tests : ~20% Wind tunnel, ~80% CFD

• CFD development : 4 engineers on Star-CCM+

• 4 Workstations, 1 Cluster of 128cores / 130 simulations in 1,5 month

Why we use more CFD in 2010?

Ratio Cost / Efficiency

Understanding the phenomena and not iterating mechanically

Aero development through the year

Investment : cluster and SKILL

New skills = new business opportunities

2. Why we use CFD?

Methodology:

Correlation

Straight-Line Test with the real Car

Lift : calculated with Loadcells on each suspension + Pitot sensor

Constant speed

Drag : Coast-down.

All the values are stored in a PI Data Analysis System:

- 4 Loads

- Aero Speed

- Ride Heights Front and Rear

- Acceleration X, Y, Z

- Ground Velocity

3. Methodology

Methodology:

Case Studies

Straight-Line

Half-car with different Ride Heights

Yaw / Roll

Full car with Yaw, Roll, Steering Angle

3. Methodology

Slipstream

3. Methodology

DRAG LIFT EFFICIENCY

LEADING CAR FOLLOWING CAR

BALANCE

LEADING CAR

FOLLOWING CAR

Fro

nt

Mesh / Solver

Mesh : Wrapper + Trimmer + Prism Layer

From 12M, up to 45M of cells

Physics :

- Steady cases

- Unsteady : coming soon...

- Porous Region for Radiators

- Velocity specification on wheels and Floor

- RANS + SST K-Omega

3. Methodology

3. Methodology

3. Methodology

Results

90% of the post-treatment is automated:

Scenes – Starview files

Analitic Results : force reports, mass-flow

Force and Mass-flow reports automated by Java macros

All Results compiled in Excel File

3. Methodology

3. Methodology

Results - Starview

3. Methodology

3. Methodology

3. Methodology

3. Methodology

3. Methodology

3. Methodology

Results – Analytic

By macros, we export analytic results:

– Forces on each parts

– Mass Flow : brake ducts, radiator

– Flow around the underfloor : velocity, pressure, angle

– Plots of Coefficient of Pressure : Rear Wing, Front Wing, Undefloor, Diffuser

3. Methodology

3. Methodology

– Forces on each parts

3. Methodology

23%

43%

39%

17%

-19% -1% 0% -1%

-30%

-20%

-10%

0%

10%

20%

30%

40%

50%

Win

g

Fro

nt S

plit

ter

Fla

t B

ott

om

Diffu

ser

Bodyw

ork

Fro

nt W

heel

Rear

Wheel

Inte

rnal

SCZ

17%19%

9%

13% 11%

3%

8%

20%

-30%

-20%

-10%

0%

10%

20%

30%

40%

50%

Win

g

Fro

nt S

plit

ter

Fla

t B

ott

om

Diffu

ser

Bodyw

ork

Fro

nt W

heel

Rear

Wheel

Inte

rnal

SCX

3. Methodology

– Flow around the underfloor : velocity, pressure, angle

3. Methodology

– Plots of Coefficient of Pressure : Rear Wing, Front Wing, Undefloor, Diffuser

Conclusions

Since 2 years, ORECA has invested a lot to increase its know-how,methodology and tools to carry extensive Aero development programs onLe Mans Prototypye. We started from Zero and have now an efficientaero-group. Our staff is on a steep learning curve.

The effort we have put in the Aero development started to pay off at the end of the 2009 season. We expect a bigger gain to come with the new LMP1.

We open with the CFD new business opportunities

Our aim is to fight with factory Teams in 2011.

Special Thanks to

Vincent Keromnès, Christian Fauchier, Christophe Gayet from CD Adapco France.

ORECA’s technical partners: CD Adapco, Dassault System, Araldite, MSC Software.