CFD & Aerodynamics At Volvo Car Corporation

Aerodynamics - CFDCFD & Aerodynamics at Volvo CarCorporationSimone Sebbenssebben@volvocars.com

Aerodynamics - CFDOutline Introduction Why work with CFD What kind of problems we look at Hands on the CFD process How we work in projects Exemples

Aerodynamics - CFDCFD groups at VCCFluid Dynamics Centre,Computational Fluid DynamicsPowertrain,Thermodynamics analysisPowertrain,Combustions systems

Aerodynamics - CFDVCC Fluid Dynamics CentreResearch and DevelopmentChassis and Vehicle DynamicsFluid Dynamics CentreMagnus BlomstrandThermodynamicsAerodynamicsCFDSystem AttributesMats LöfmanAlexander BroniewiczHans EnwaldGöran Karlsson

Aerodynamics - CFDVCC Fluid Dynamics CentreThermodynamicsCooling PerformanceThermal Environment:Engine bayFloorAir Intake / Intercooler13 People:3 Mechanics2 B.Sc.7 M.Sc.1 Lic.AerodynamicsCFDSystem Attrib.DragStabilityDirt DepositionWater TightnessAerodynamicsClimatic ComfortThermodynamicsDirt DepositionAerodynamicsThermodynamicsDirt DepositionWater Tightness11 People:1 Mechanics7 M.Sc.1 Lic.2 Ph.D15 People:5 M.Sc.1 Lic.8 Ph.D13 People:5 B.Sc.7 M.Sc.1 Lic.Requirement specification, Customer requirements, Project managementTesting / System simulations, R&D / method development Plus 1 Aerodynamicist resident at the Design Studio

Aerodynamics - CFDCFD Aerodynamics:Magnus Ahl, Ms.C.Jonas Ask, Ph.D. studentAndreas Borg, Ph.D.Olga Roditcheva, Ph.D.Simone Sebben,Ph.D.

Aerodynamics - CFDWhy work with CFD? UNDERSTANDING: complete picture of the flow field atany timeCOMPLEMENTS physical testingShow CONSEQUENCES of choices early on in project,balancing of requirementsMeets the need for REDUCED LEAD TIMESuccessful factors of our CFD group: Competent staffComputer environmentWorking process

Aerodynamics - CFDFundamental fluidmechanics & CFDresearchUniversitiesConnection to Academic ResearchCFD research workfor future automotiveapplicationsDevelopment ofcomputational proceduresaccording to technologyStrategies (help of ex-job work)VCC Ph.D.projectsC omputational FApproximate:resource allocation10 %luidDynMethod dev.projectsamics Gr oup, 920 %6630R&D andVehicleprojects70 %

Aerodynamics - CFDAerodynamic issues Drag (fuel consumption, top speed, acceleration) High-speed stability (lift) Cross-wind stability (side force and yawing moment) Passenger comfort (cabriolets) Dirt deposition (visibility) Aero acoustics (limiting the strength of sources) Body deformation (Door frames etc)

Aerodynamics - CFDSources of drag on a modern car45 %25 %30 %

Aerodynamics - CFDWhat we do: Flat underbody imulations Detailed underbody simulations Dirt deposition /underbody contamination

Aerodynamics - CFD Snow ingress analysis based on models fromthermal analysis Aeroacoustic analysis based on modelledacoustic source terms Confort in convertibles

Aerodynamics - CFDHands on CFD processVPM/CATIAANSAIcem-CFD/TGridStar -CDEnsightGeometry dataVPM: Data base of VS

Aerodynamics - CFDHands on CFD processVPM/CATIAANSAIcem-CFD/TGridStar -CDEnsightClean up CAD and generate surface mesh

Aerodynamics - CFDHands on CFD processVPM/CATIAANSAIcem-CFD/TGridStar -CDEnsightGenerate volume mesh

Aerodynamics - CFDHands on CFD processVPM/CATIAANSAIcem-CFD/TGridStar -CDEnsightSet-up case & solver

Aerodynamics - CFDHands on CFD processPost processingVPM/CATIAANSAIcem-CFD/TGridStar -CDEnsight

Aerodynamics - CFDCFD - HardwareWorkstations15 HP FX6-10 Graphics,3 –8 GB3 SGI Octane, 4 GBServers2 IBM Linux cluster:3x12 CPU: Intel 3.06GHzXeon2x8 CPU: Intel 2.2GHzPentium 4

Aerodynamics - CFDProject work Requirements specification Tests / Computations Analyses Recommendations & design guidelines Information and implementation

Aerodynamics - CFDProduct development phasesConcept study Generic shape studies Evaluate styling proposals Define underfloor conceptsPrestudy Develop frozen design Develop underfloor solutionsProject Detail optimization Verification

Aerodynamics - CFDExemples: Flat underbody simulations Detailed and quick analysis of the flow field Recommendations on exterior body shape Used at very early stages of the project Used for Cd/dCd comparisons among models Lead-time: 1 to 2 weeksSurface restricted streamlines

Aerodynamics - CFDVisualization ofthe wakePressure distribution on the car

Aerodynamics - CFDEffect of tailgate spoiler on base pressureWithout spoilerWith spoiler

Aerodynamics - CFDSide wind simulations Detailed and quick analysis of the flow field Recommendations on exterior body shape Used for analysing effects of side forces Effect on handling Lead-time: 1 to 2 weeksRepresentation of the wake withyaw 10 degreesRepresentation of the wake withyaw 30 degrees

Aerodynamics - CFD Cylindrical windtunnel One mesh for different angles BC control the wind angle Good results on squarish shapes.Drag0.50.450.4d 0.35C0.3S imula tionP VT P roduction Ca rDNW Full S ca le #15DNW Full S ca le #220.250.2010203040

Aerodynamics - CFDDetailed underbody simulations Detailed analysis of the flow field Recommendations on underbody parts (deflectors,pannels) Used at any stage of the project Used for Cd / dCd comparisons among configurations / models Large models, hybrid meshes of 7 - 10 million cells Lead-time: 5 to 7 weeks for a completely new model3 days for configurations

Aerodynamics - CFDVelocity planes and pressure distribution

Aerodynamics - CFDContribution of the individualparts of the underbody to Cd*A.Easy to identify problematicareas or zones of improvementdue to aditional parts (ex.deflectors, rear pannel)

Aerodynamics - CFDUnderbody contamination Water mist contaminated with dirt particlesis entering the rear rims causing unbalance The water mist is generated from the frontwheels The biggest factor to affect the dirtdeposition in the rims is the underbody airflow.

Aerodynamics - CFDThe effect of underbody deflectorsand body plates to reduce dirtdepostion in rear rims.Dirt deposition in rear rim

Aerodynamics - CFDhits on rear-susp. parts and wheelsNo deflector 79 of 1045, 7.5 %Deflector 38 of 1045, 3.6 %No deflector, 6 % of released nrDeflector 4.3 % of released nr

Aerodynamics - CFD SNOW DUST, ENGINE AIR FILTER INSTALLATIONCFD: Method toapproximately predictthe intake of snow intothe air filter(understandingmechanisms)

Aerodynamics - CFDGeometry of the air intakeNew ideas

Aerodynamics - CFDImprovement with new designsTotal no of particles 40 000

Aerodynamics - CFDDirt deposition on the rear screenWithout rear tailgate spoilerWith rear tailgate spoiler Counterclockwise flow Clockwise flow

Aerodynamics - CFDWithout wingWith wingSmoke visualisation

Aerodynamics - CFDComfort in convertibles - C70 Driving a convertible roof-down at high-wayspeeds is by no means comfortable. The recirculating air entering the compartmentreaches 15 m/s when driving 90 km/h. Introducing a windblocker keeps therecirculation bubble above the rear seat. Flow speed is kept below 2 m/s in the frontseat when driving 90 km/h. The windblocker is modelled as a permeablesurface with a prescribed pressure drop. A windblocker is sold as an accessory to C70.

Aerodynamics - CFDPh.D. project & RD project on Aeroacoustics Increase knowledge about aeroacoustics Develop engineering tool for analysis Initial focus - rearview mirror and A-pillar Later on - underbody and climate system noiseWant coupled analysis - e.g. drag, dirt, noise

Aerodynamics - CFDAero Concept CarCd 0,20

Aerodynamics - CFDACC Final Design 1999

Aerodynamics - CFDImportant parameters - drag of basic shape StationwagonSweeping of roofBoat-tailing SedanAngle of rear windowLength, height and angle of boot-lid SportswagonAngle of rear tailgateBoat-tailing HatchbackAngle of tailgateRadius where roof meets tailgateC-post Front end (common for all variants above)Orientation and size of stagnation region surface.Radius from front to hoodIncline of hoodRake of windscreen

Aerodynamics - CFDAerodynamics, CFD and Volvo Heading for different areas of interest Aeroacoustics Dirt-deposition (water, sand, snow) Handling

Aerodynamics -CFD Connection to Academic Research VCC Ph.D. projects R&D and Vehicle projects Universities Method dev. projects Co mput atio nal Fl uid Dyna mics Grou p,96 630 Fundamental fluid mechanics & CFD research CFD research work for future automotive applications Development of comput