volvo cfd

KTH, Johan Ljungberg, jljungb3

Page 12011-03-25Issue date: 2010-04-19, Security Class: Public

AerodynamicsAerodynamics and CFD and CFD

at Volvo Car Corporationat Volvo Car Corporation

Johan Ljungberg Johan Ljungberg

[email protected]@volvocars.com



Present at the CFD group: 16 employees

Graduated from KTH 2005

Scania AB 2005-2006

Volvo Cars 2006-

Volvo graduate program

www.volvocars.com/intl/top/about/corporate/career/pages/graduate_program.aspx



OutlineOutline

• Introduction

• CFD process

• Hardware and Software

• Aerodynamics CFD

• Strengths of using CFD



What is CFDWhat is CFDThe analysis of fluid flow, heat transfer, and other related

phenomena with the aid of advanced numerical techniques,

softwares and computers.

Why CFDWhy CFDUNDERSTANDING complete picture of the flow field at any time

COMPLEMENTS physical testing

Meets the need for REDUCED LEAD TIME



History of the CFD GroupHistory of the CFD Group1990: Basically 2D computations

1991: 1:st computation of 3D external flow calculation

100000 cells

lead time 3 to 4 months

1993: lead time of 6 weeks

possibility of using CFD in the early stages of car

development

2000: focus becomes model complexity

lead time 8 weeks

2010: lead time for a detailed floor calculation is 4 weeks

60 million cells (2 days for a configuration)



CAE Groups at VCCCAE Groups at VCC

Computational Fluid DynamicsDurability and NVH

Safety and crash

Powertrain,

Thermodynamics analysis

Combustion Systems

Powertrain,


Combustion Systems

Powertrain,


Combustion Systems

Durability and NVH

CAE Groups at VCCCAE Groups at VCC

Durability and NVHDurability and NVH



CLIMATE SYSTEMSCLIMATE SYSTEMSTHERMODYNAMICSTHERMODYNAMICS

CONTAMINATIONCONTAMINATIONAEROACOUSTICSAEROACOUSTICS



SoftwareSoftware

Preprocessing:

TCE

ANSA

Harpoon

Tgrid (FLUENT)

Pro-am (STAR-CD)

Solver:

FLUENT

Radtherm

Post processing:

Ensight

FLUENT (Cfd-post)

MATLAB



3) Simplied

TCECAD-Extraction

ANSA

ProAM Wrap

HARPOON

FLUENT

ENSIGHT

CFD ProcessCFD Process



TCE

CAD-Extraction

ANSA

ProAM Wrap

HARPOON

FLUENT

ENSIGHT

Wrapping of complex

Geometries to get an

air tight geometry




TCE

CAD-Extraction

ANSA

ProAM Wrap

HARPOON

FLUENT

ENSIGHT

Pre-work for

wrapping


Clean Exterior



TCE

CAD-Extraction

ANSA

ProAM Wrap

HARPOON

FLUENT

ENSIGHT

Octree based

Volume mesher




TCE

CAD-Extraction

ANSA

ProAM Wrap

HARPOON

FLUENT

ENSIGHT




TCE

CAD-Extraction

ANSA

ProAM Wrap

HARPOON

FLUENT

ENSIGHT




SERVER – 520 CPU:s(extra access to crash CPUs in case of free slots)

HardwareHardware

PC

VISTA (64 bits), 64-96 GB, 2 ProcessorsUsed for pre- and post-

processing

Used for the Solver



Closed front / semi detailed

Aerodynamics CFDAerodynamics CFD

Closed front, i.eno cooling flow

Symmetrycondition

Open front / fully detailed

Detailed engine

compartment

None symetric



Exterior optimization: closed front


Late separation Good separation




Iso surface total pressureVelocity plane 100mm downstream base

Exterior optimization: closed front

Skin friction



+30 mmRef

-15 mm-30 mm


Roof height study: S80

Morphing



+30 mmRef-15 mm

-30 mm


Roof height study: S80

Morphing



Greenhouse study: S80

Ref-10 mm-20 mm-30 mm

Aerodynamics CFDAerodynamics CFDMorphing



Underbody optimization: open front

Aerodynamics CFDAerodynamics CFD Cooling flow needed to optimize underbodydetails as deflectors

and underbody panels



Challanges with wheel house aerodynamics




Force (N) Cd*A Cd %

Exterior 153,9 0,331 0,143 48,5

Front Wheels 23,6 0,051 0,022 7,5

Rear Wheels 16,4 0,035 0,015 5,2

Front Suspension 7,1 0,015 0,007 2,2

Rear

Suspension 8,7 0,019 0,008 2,8

Front Wheel

Deflectors 8,1 0,018 0,008 2,6

Cooling

Package 97,3 0,209 0,090 30,7

Drive line 64,2 0,138 0,060 20,3

Floor -62,4 -0,134 -0,058 -19,7

TOTAL 317,25 0,682 0,295 100,0


CD vs x

Drag per part



• It is cheaper and faster than wind tunnel tests at early stages of the car development

• It provides the complete picture of the flow field

• It allows the brake down of the model for easier interpretation of the forces

• It allows direct comparison of the flow and local forces betweenconfigurations

• It is an excellent support and complement to wind tunnel tests

• Powerful tool to be used in combination with optimization

Strengths of using CFDStrengths of using CFD



STCC & WTCCSTCC & WTCC

ThankThank you! you!

Documents

volvo cfd