Multidisciplinary Design Analysis and Optimisation of Rear Wings for Sports Cars Aerospace ...

124 Pages·2016·10.97 MB·English

by  Andre C. Marta

Multidisciplinary Design Analysis and Optimisation
of Rear Wings for Sports Cars
Miguel da Silva Ferreira
Thesis to obtain the Master of Science Degree in
Aerospace Engineering
Supervisor: Prof. André Calado Marta
Examination Committee
Chairperson: Prof. Filipe Szolnoky Ramos Pinto Cunha
Supervisor: Prof. André Calado Marta
Member of the Committee: Prof. Miguel António Lopes de Matos Neves
June 2016
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Acknowledgments
I would like to thank Prof. Andre´ Marta for his knowledge and guidance throughout the elaboration of
thisdissertation.
I would also like to thank Prof. Miguel Matos Neves, for his support and in introducing me to the
CAD/FEM team of the Instituto de Plasmas e Fusa˜o Nuclear (IPFN). A special thank you to the IPFN,
in allowing me to use an ANSYS(cid:13)R License to achieve the proposed objectives of this dissertation. In
particular, to Prof. Hugo Policarpo for special motivation, guidance, and provide all the means at its
disposal to help me with the varied ANSYS(cid:13)R related obstacles faced. Also to Paulo Quental, IPFN
researcher,forhisdisposalinalwayshelpingmewiththeseveralchallengesfaced.
This project was a culmination of the last six years of completing my degree which would not be
possiblewithoutmyfriends,andthefriendsmadeinthistime. Averyspecialthankyouto´IuriFigueiredo,
forthecompanionandsupportinthelastmonthsofthecourseofthisdissertation.
ToMariaPissarra,foralltheaffectionandsupportinthehardesttimes.
Tomyfamily,Iamdeeplygratefulforthecontinuedknowledgeandsupportinallmyendeavors.
Finally, I would like the express my deep love to my Godfather, Anibal da Silva, one of the most
incredibleandwonderfulpersonsIhaveevermet. Thisdissertationisdedicatedtohim.
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Resumo
A presente dissertac¸a˜o apresenta uma optimizac¸a˜o aero-structural de designs de asas traseiras in-
vertidas para minimizar a resisteˆncia aerodinaˆmica e a massa estrutural. Dado que estes dispositivos
teˆm uma elevada influeˆncia na performance de ve´ıculos, de modo a obter designs o´ptimos efica´zes e
seguros,amultif´ısicaenvolvidafoiasseguradaatrave´sdainteracc¸a˜ofluido-estrutura.
Oprincipalobjectivofoidesenvolveraimplementac¸a˜odeumametodologiaparaodesigndedispos-
itivosaerodinaˆmicosautomo´veiso´ptimos. Pararesolveroproblemadeoptimizac¸a˜oaero-estrutural,foi
aplicadaumaplataformadeprojecto,ana´liseeoptimizac¸a˜omultidisciplinar. Doiscasosdeestudoforam
considerados: umaestrate´giadedesign convencionalutilizadaemaplicac¸o˜esautomo´veisgeraisede-
sportivas; e um design proposto, onde a superf´ıcie de conexa˜o entre as placas laterais e os suportes
verticaise´ utilizadaparagerarsustentac¸a˜onegativaadicional.
Para assegurar a sinergia multidisciplinar e obter soluc¸o˜es fidedignas, um software de engenharia
assistidaporcomputadorfoiutilizado(ANSYS(cid:13)R Workbench14.5).
O projecto foi dividido em treˆs partes: as configurac¸o˜es dos diferentes modelos nume´ricos, os es-
tudos parame´tricos aerodinaˆmicos e estruturais (focados nos efeitos das varia´veis de projecto) e as
optimizac¸o˜esaerodinaˆmicaseestruturais(focadasnasvaria´veisdemaiorimpacto)paraobterdesigns
o´ptimos.
Apartirdosestudosrealizadosnestadissertac¸a˜o,umaplataformadedesign ana´liseeoptimizac¸a˜o
multidisciplinar foi desenvolvida para o design preliminar de asas traseiras invertidas, o qual pode ser
tambe´m aplicado a quaisquer outros dispositivos aerodinaˆmicos automo´veis. Gerac¸a˜o da malha e
a modelac¸a˜o da turbuleˆncia sa˜o aspectos importantes no que respeita a qualidade e precisa˜o das
soluc¸o˜es nume´ricas e para problemas com deformac¸o˜es pequenas, usando uma estrate´gia one-way
deinteracc¸a˜ofluido-estruturatemvantagescomputacionaissignificativas.
Palavras-chave:
Problemaaero-estrutural,Interacc¸a˜ofluido-estrutura,Engenhariaassistida
porcomputador,Dispositivosaerodinaˆmicos,Materiaiscompo´sitos.
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Abstract
This thesis covers aero-structural optimisation of rear wing designs to minimise aerodynamic drag and
structuralmass. Thesestructureshighlyinfluencetheperformanceofvehicles, andinordertoachieve
effectiveandsafeoptimaldesigns,themultiphysicsinvolvedwasconsideredbymeansoffluid-structure
interaction(FSI).
The objective was to fold the implementation of a process for optimal automotive aerodynamic de-
vices design. To solve the aero-structural optimisation problem, a multidisciplinary design analysis and
optimisation(MDAO)frameworkwasapplied. Twostudycaseswereconsidered: atraditionalrearwing
design strategy used in automotive and motorsport applications; and a proposed design, where the
surfaceconnectionbetweentheendplatesandverticalsupportsisusedtocreateadditionaldownforce.
Concerningthemultidisciplinarysynergytoobtainfeasiblesolutions,aComputerAidedEngineering
(CAE)softwarewasused(ANSYS(cid:13)R Workbench14.5).
Theprojectwasdividedintothreeparts: thenumericalmodelssettings,theaerodynamicandstruc-
turalparametricstudies(focusedontheeffectsofthedesignvariables),andaerodynamicandstructural
optimisationproblems(focusedonthemostimpactingvariables)toobtainoptimaldesigns.
From the studies performed in this thesis, a MDAO process for optimal preliminary design was de-
veloped for rear wings, but it can also be applied to any other automotive aerodynamic devices. Mesh
andturbulencemodellingstrategyprovedtobeveryimportantregardingtheaccuracyofthenumerical
solutions and for problems with small deformations, a one-way FSI coupling technique has significant
computationaladvantages.
Keywords:
Aero-structural problem, Fluid-structure interaction, Computer-aided engineering,
Aerodynamicdevices,Compositematerials.
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Contents
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii
Resumo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
ListofTables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
ListofFigures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv
Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xix
Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxiii
1 Introduction 1
1.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 RearWingOptimalDesign . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2.1 DesignConsiderations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2.2 MultidisciplinaryDesignAnalysisandOptimisationFramework . . . . . . . . . . . 4
1.3 ThesisObjectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.4 DissertationStructure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2 AutomotiveAerodynamics 7
2.1 HistoryofAerodynamicsinPerformanceCarsDesign . . . . . . . . . . . . . . . . . . . . 7
2.1.1 TheImpactofMotorsportAerodynamicsonProductionCars . . . . . . . . . . . . 9
2.2 PerformanceCarsAerodynamicDevices. . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2.1 Vehicle’sFront-End. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2.2 Vehicle’sUnder-body . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.2.3 Vehicle’sBack-End . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.3 MethodsusedforEvaluatingAutomotivePerformance . . . . . . . . . . . . . . . . . . . . 13
2.3.1 NumericalSimulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.3.2 WindTunnelTesting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.3.3 RoadandTrackTesting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3 TheoreticalBackground 17
3.1 AerodynamicTheory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.1.1 GoverningEquationsofFluidFlow . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
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3.1.2 TurbulentFlowsandTurbulenceModelling . . . . . . . . . . . . . . . . . . . . . . . 18
3.2 StructuresTheory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.2.1 GoverningEquationsofSolidStructure . . . . . . . . . . . . . . . . . . . . . . . . 21
3.2.2 First-OrderDeformationTheory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.3 Fluid-StructureInteraction(FSI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.3.1 MonolithicandPartitionedMethods . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.4 MultidisciplinaryDesignAnalysisandOptimisation(MDAO) . . . . . . . . . . . . . . . . . 26
3.4.1 MDAOArchitectures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3.4.2 NumericalOptimisationTechniques . . . . . . . . . . . . . . . . . . . . . . . . . . 26
4 MethodologyandNumericalModels 29
4.1 MDAOinANSYS(cid:13)R Workbench14.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.2 CADModel: ANSYS(cid:13)R DesignModeler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
4.3 CFDModel: ANSYS(cid:13)R Fluent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
4.3.1 ModelValidationwithNACA4415AirfoilTwo-DimensionalAnalyses . . . . . . . . 31
4.3.2 BenzingBE122-125AirfoilThree-DimensionalAnalyses . . . . . . . . . . . . . . 36
4.4 CSMModel: ANSYS(cid:13)R CompositePrepPostandMechanical . . . . . . . . . . . . . . . . 39
4.4.1 FiniteElementAnalysisSetup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
4.5 FSIModel: ANSYS(cid:13)R SystemCoupling . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
4.5.1 One-WayversusTwo-WayCoupling . . . . . . . . . . . . . . . . . . . . . . . . . . 44
4.6 OptimisationModel: ANSYS(cid:13)R DirectOptimisation . . . . . . . . . . . . . . . . . . . . . . 46
5 Results 51
5.1 MDAODesignVariablesandFunctionsofInterest . . . . . . . . . . . . . . . . . . . . . . 51
5.2 CADParametricDesign . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
5.2.1 AirfoilSelection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
5.2.2 EndplateDesign . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
5.2.3 VerticalWingSupportDesign . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
5.2.4 FlowDesign . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
5.2.5 Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
5.3 AerodynamicParametricStudies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
5.3.1 EffectofHorizontalandVerticalPositioningofLowerWings . . . . . . . . . . . . . 58
5.3.2 EffectofChord,WingspanandAngleofAttack . . . . . . . . . . . . . . . . . . . . 60
5.3.3 EffectofEndplatesDimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
5.3.4 VerticalSupportsPositioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
5.4 AerodynamicOptimisation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
5.5 One-WayFSIStructuralParametricStudies . . . . . . . . . . . . . . . . . . . . . . . . . . 69
5.5.1 EffectofMaterialType . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
5.5.2 EffectofNumberandOrientationofCompositePlies . . . . . . . . . . . . . . . . . 70
5.6 One-WayFSIStructuralOptimisation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
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