OverviewandSummaryoftheThirdAIAAHighLiftPredictionWorkshop
ChristopherL.RumseyNASALangleyResearchCenter
Hampton,VA
JeffreyP.SlotnickTheBoeingCompany
Seattle,WA
AnthonyJ.SclafaniTheBoeingCompany
LongBeach,CA
AIAASciTech,Kissimmee,FL,January8-12,2018 1
Overview• GeneralsummaryofHiLiftPW-3results.• CFDcomparisonsagainstitself(consistency,verification).• CFDcomparisonsagainstexperiment(validation).
• HavethingsimprovedsinceHiLiftPW-2?• Whathavewelearned?• WhatshouldbedonedifferentlyforHiLiftPW-4?
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Outline• Introduction• Highliftgeometriesandexperimentaldata• Gridsystems• Summaryofentries• Results• Turbulencemodelingverification• HL-CRM• JSM
• Statisticalanalysis• Conclusions
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Wherewe’vebeen(somehighlights)• HiLiftPW-1(2010).• NASATrapezoidalWing-Body;includingeffectofflapdeflection.• CFDtendedtounderpredict lift;bigspreadnearstall.• NosupportbracketswereincludedintheCFD(whentheywere,predictedliftwasevenlower).• Transitionmodelingseemedtohelpimprovecomparisonswithexperiment.• Flownearwingtipwasverydifficulttopredict.
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Wherewe’vebeen(somehighlights)• HiLiftPW-1(2010).• NASATrapezoidalWing-Body;includingeffectofflapdeflection.• CFDtendedtounderpredict lift;bigspreadnearstall.• NosupportbracketswereincludedintheCFD(whentheywere,predictedliftwasevenlower).• Transitionmodelingseemedtohelpimprovecomparisonswithexperiment.• Flownearwingtipwasverydifficulttopredict.
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Wherewe’vebeen(somehighlights)• HiLiftPW-2(2013).
• DLR-F11Wing-Body;includingeffectofReynoldsnumber.• CFDsometimesunderpredicted,sometimesoverpredicted lift;againshowedbiggerspreadnearstall.
• Separationbehindslattrackswasprobablyinfluentialininitiatingstall;evenwhenincludingbrackets,CFDusuallygotitwrong(e.g.,separationbehindwrongbrackets).
• Nocleartrendswithtransitionmodelingstoodout.• Attainingsteady-stateconvergencesometimesdifficult.• ExperimentaloilflowswereextremelyusefulfordeterminingwhetherCFDwascapturingthephysicscorrectlyornot.
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Wherewe’vebeen(somehighlights)• HiLiftPW-2(2013).
• DLR-F11Wing-Body;includingeffectofReynoldsnumber.• CFDsometimesunderpredicted,sometimesoverpredicted lift;againshowedbiggerspreadnearstall.
• Separationbehindslattrackswasprobablyinfluentialininitiatingstall;evenwhenincludingbrackets,CFDusuallygotitwrong(e.g.,separationbehindwrongbrackets).
• Nocleartrendswithtransitionmodelingstoodout.• Attainingsteady-stateconvergencesometimesdifficult.• ExperimentaloilflowswereextremelyusefulfordeterminingwhetherCFDwascapturingthephysicscorrectlyornot.
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Quickcomparison
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HiLiftPW-1 HiLiftPW-2 HiLiftPW-3
37submissions 48submissions 79submissions
HiLiftPW-3geometriesandexperimentaldata
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HL-CRM JSM
NotyetbuiltTestedinJAXA-LWT1inearly2000s- Notripping
ForcesMomentCpOilflowSometransitioninfo
HiLiftPW-3geometriesandexperimentaldata
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HL-CRM JSM
NotyetbuiltTestedinJAXA-LWT1inearly2000s- Notripping
ForcesMomentCpOilflowSometransitioninfoHiLiftPW-3alsopartnered
with thefirstGeometryandMeshGenerationWorkshop(GMGW-1),usingHL-CRM
Committee-providedgridsystems
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Averagemedium grid:approx 71Mpointsand120McellsMedianmedium grid:approx 52Mpointsand107Mcells
ForHL-CRMandJSM
Summaryofentries• 35individuals/groupswith79entries.
• 14differentcountries(40%U.S.).• Broadrepresentationfromindustry,academia,CFDvendors,andgovernmentresearchlabs.
• Turbulencemodels:• MostusedSAorvariant(RC,R,neg,QCR,noft2).• K-omegatype:BSL,SST,SST-V,SST-V-sust,SST-2003,SSTwmods,Wilcox1988,Wilcox1988CC.• Lag-EB-ke.• SSG/LRR-RSM-w2012.
• Transitionmodels:• SST-gamma,AFT2017b,gamma-Ret-SST.
• Non-RANS:• FiniteelementwithimplicitSGSmodel.• LBwithVLESwallmodel.• LBwithWALESGSmodel.• DDES.
• Noteveryonesubmittedallrequestedcases.• Detailsinpaper.
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Results• Turbulencemodelingverification• HL-CRM• JSM
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Results• Turbulencemodelingverification• HL-CRM• JSM
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DSMA661(ModelA)airfoil,M=0.088,alpha=0deg,ReC=1.2million(JFM160:155-179,1985)
Turbulencemodelingverification
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OnlycompletedforSAmodel(SA,SA-neg,SA-noft2)
Theimportantroleofverification
2-Dverificationcase
VERIF/2DANWcasefromTMRwebsite:https://turbmodels.larc.nasa.gov
VerificationremovesonepossiblesourceofCFDuncertainty,foragivenmodel.Othersources:grid(size,extent,adherencetogeometry),BCs,iterativeconvergence.
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8differentcodesproducenearlyidenticalresultsforSAmodel(CFL3D,FUN3D,Kestrel/COFFE,CFD++,OVERFLOW,BCFD,TAU,andLAVA)
Approximately30% ofthecodesthatrantheverificationcasewerefullyverified fortheSAmodel
Additionalverificationexercisesstillneededforothermodels,includingSAvariants
Results• Turbulencemodelingverification• HL-CRM• JSM
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Focusingononlyafewmainpointshere;furtherdetails(suchaseffectofflapgaptreatment)aregiveninthepaper
HL-CRMgridconvergence(allresults)
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alpha=8deg. alpha=16deg.
DragandmomentshowninpaperNote:bluecurvesrepresentgrid-adaptionresults
Theimportantroleofverification
2-DverificationcaseHL-CRM
SAmodelsonly
BluelinespassedtheverificationtestforSA
VERIF/2DANWcasefromTMRwebsite:https://turbmodels.larc.nasa.gov
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8differentcodesproducenearlyidenticalresultsforSAmodel(CFL3D,FUN3D,Kestrel/COFFE,CFD++,OVERFLOW,BCFD,TAU,andLAVA)
Theimportantroleofverification
2-DverificationcaseHL-CRM
SAmodelsonly
VERIF/2DANWcasefromTMRwebsite:https://turbmodels.larc.nasa.gov
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8differentcodesproducenearlyidenticalresultsforSAmodel(CFL3D,FUN3D,Kestrel/COFFE,CFD++,OVERFLOW,BCFD,TAU,andLAVA)
BluelinespassedtheverificationtestforSA
HL-CRMvelocityprofiles
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FLAP:x=1615,y=638 MAIN:x=1495,y=638
Results• Turbulencemodelingverification• HL-CRM• JSM
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Focusingononlyafewmainpointshere;furtherdetailsaregiveninthepaper
JSM,nonacelle/pylon
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Liftcoefficient Dragcoefficient Momentcoefficient
JSM,withnacelle/pylon
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Liftcoefficient Dragcoefficient Momentcoefficient
JSM,deltasbetweennacelle/pylononandoff
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Liftcoefficient Dragcoefficient Momentcoefficient
Exceptforoneoutlier,participantspredicteddeltaswell(albeitlargescatternearmaxlift)
CFDresultsthatagreed“best”withJSMCL data
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Nonacelle/pylon Withnacelle/pylon
Minimize!"Σ 𝐶𝐿, 𝐶𝐹𝐷 − 𝐶𝐿, 𝑒𝑥𝑝
2
(ignoringresultswithno/lateCL,max)
SASALBVLESSASA-RC-QCRSA-RC-QCRW98CC+transLBWALESST[mod]
SA-QCRSA-negSA-negSA-RC-QCRSA-RC-QCRW98CCW98CC+transLBWALESST[mod]
Generalobservationfromtheworkshop• MostoftheRANScodesproducedsurfaceflowsthathadtoomuchseparationnearthewingtipcomparedtotheexperimentandnotenoughseparationnearthewingrootatandbeyondmaxlift.• Notableexceptions:scale-resolvingmethods(likeLB).
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Exp,alpha=18.58deg. Exp,alpha=21.57deg.
Generalobservationfromtheworkshop• MostoftheRANScodesproducedsurfaceflowsthathadtoomuchseparationnearthewingtipcomparedtotheexperimentandnotenoughseparationnearthewingrootatandbeyondmaxlift.• Notableexceptions:scale-resolvingmethods(likeLB).
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Exp,alpha=18.58deg. Exp,alpha=21.57deg.
(notionaltypicalRANS)
JSM:surfacepressurecoefficients
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A-A B-B C-C
E-E G-G H-H
Mainelement,alpha=21.57deg.,nonacelle/pylon
JSM:issuesnearCL,max
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Nonacelle/pylon Withnacelle/pylon
GridandtemporaltreatmentbothhavebiginfluenceSamecode&model,differentgrid
Samecode&model,differentgridSamecode,model&grid,time-accuratevs.steady-state
JSM:furtherevidenceofinsufficientgriddensity
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All“SA-verified”codesdonotagreewellusingSAon(different)mediumgrids
COFFE,gridC1TAU,gridBTAU,gridf(nc)OVERFLOW,gridATAU,gridBLAVA,gridAFUN3D,gridC1FUN3D,gridC2
Andbluecurvespointtominorissueswithinsufficientiterativeconvergenceand/orcodesetting/versiondifferences
JSM:effectoftransitionmodels
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Nonacelle/pylon Withnacelle/pylon
• TransitiondefinitelypresentatthisRe• For030.1vs.030.3(committeegridE),littleinfluenceoftransitionnoted• For030.2vs.030.4(participantgridb),transitioncausedhigherCL inthe
linearrangeandanearlierstall,inbetteragreementwithexperiment
SST-gammaSA-RC-QCR+AFT2017bW98CC+transW98CC+trans
SA-RC-QCR+AFT2017bW98CC+trans
Statisticalanalysis:HL-CRM• Mainconclusion:generalscatterdidnotalwaysdecreasebetweenthemediumandfinegrids,aswouldbeexpectedifnumericalerrorduetogridresolutionwastheprimarysourceofvariation.
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Notch=medianDiamond=mean
Upperandlowerquartiles
Minvaluethatisconsideredstatisticallysignificant
OutlierShadingrepresentsdistribution
Statisticalanalysis:JSM
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alpha=4.36deg. alpha=14.54deg. alpha=20.59deg.
Cv=σ/𝜇 =standarddeviation/medianScatterlimits=µ ± 𝐾𝜎(𝐾 = 3� )
Focusingononlyafewmainpointshere;furtherdetailsaregiveninthepaper
HasCFDgottenanytightersinceHiLiftPW-2?
Cases Cv,lowalpha Cv,midalpha Cv,highalpha
HiLiftPW-2,alpha=7,16,20deg.
0.038 0.057 0.060
HiLiftPW-3, alpha=4.36,14.54,20.59deg.
0.025 0.017 0.073
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LowRe,withbrackets,mediumgrids
YES YES NO
Conclusions• Intheverificationcase,only30%oftheCFDcodesthatparticipatedwiththeSAturbulencemodelwerefullyverified.• HL-CRMcaseexploredgridconvergence.
• SpreadbetweenCFDresultsdidnotdiminishonfinegrids(similartoHiLiftPW-2).• Lackofverificationinsomecodesmayexplainpartofthespread.
• JSMexploredeffectofnacelle/pyloninstallation.• Useof“medium”gridonly;deltasweregenerallywellpredicted.• LargespreadinCFDresultsnearCL,max (similartoHiLiftPW-1and2).• SignificantinfluenceofgridnearCL,max,so”medium”gridprobablynotfineenough.• Transitionshouldbeimportantforthiscase,buttransitionmodelswerenotalwaysbetter(gridinfluence?).
• Manyindividualresultscomparedverywellwithexperimentalliftcurve;butwedonotknowwhy.
• Itwaspossibletogetintegratedquantitiesrightforthewrongreasons.• Scale-resolvingmethodsappearedtopredictseparationpatternsbetterthanRANS.• Participantsweremoreconsistent(comparedtoHiLiftPW-2)predictingcomplexhigh-liftconfigurationatlowRewithallmountingbrackethardwareatlowalphas– BUTNOTNEARCL,max.
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HiLiftPW-4statusandotherquestions/thoughts• WhatshouldbedonedifferentlyinHiLiftPW-4,sothatwelearnmore?• Proposal:requiretheuseofoneormorespecific(verified)models.
• Identifythe“best”(publicly-available)RANSmodel(s)fromthisworkshop,andrequestthatallRANSparticipantsverifyit intheircodeanduseit.
• Allowadditionalresultsusinganymodelormodelvariant.• NearCL,max: encouragelargergrids,moregridadaption,higherorder,time-accurate,moreuseofscale-resolvingmethods.• Nomorefree-airCFDruns;trytomatchthewindtunnelsemispan testinggeometryandBCs.
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End
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Backup
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Introduction• Specificworkshopseriesfocusedonthepredictionofswept,medium/high-aspectratiowingsinlanding/takeoff(highlift)configurations.• GoalsofHiLift workshopseries:• Assessthenumericalpredictioncapability ofcurrent-generationCFDtechnology.• DeveloppracticalmodelingguidelinesforCFDpredictionofhighliftflowfields.• Advancetheunderstandingofhighliftflowphysicstoenabledevelopmentofmoreaccuratepredictionmethodsandtools.• EnhanceCFDpredictioncapabilityforhighliftaerodynamicdesignandoptimization.• Provideanimpartialforum.• Identifyareasneedingadditionalresearchanddevelopment.
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Testcases• Case1- GridConvergenceStudyontheNASAHL-CRM(freeair,fullyturb).
• 1a:Fullchordflapgap,M=0.2,ReMAC=3.26M,alpha=8,16deg.• 1b:Sameas1a,withgridadaption.• 1c:Sameas1aexceptpartially-sealedflapgap.• 1d:Sameas1c,withgridadaption.
• Case2- NacelleInstallationStudyontheJSM(freeair,fullyturb orwithtransition).• 2a:Nacelle/pylonoff,M=0.173,ReMAC=1.93M,sixalphas.• 2b:Sameas2a,withgridadaption.• 2c:Sameas2aexceptNacelle/pylonon.• 2d:Sameas2c,withgridadaption.
• Case3- TurbulenceModelVerificationStudy(fullyturb).• VERIF/2DANWfromhttp://turbmodels.larc.nasa.gov
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Black=requestedBlue=optional
Gridsystems
Label Gridtool Org Type Coarse Medium Fine Extra-fine Notes
A-HLCRM ANSA+Chimera
NASA str 24/23 65/64 189/185 564/554 Overset
B1-HLCRM Pointwise Pointwise unstr 8/48 26/157 70/416 206/1228 Tet
B2-HLCRM Pointwise Pointwise unstr 8/22 26/65 70/170 206/541 Mixedprism/tet
B3-HLCRM Pointwise Pointwise unstr 8/18 27/48 71/119 208/397 Mixed
C-HLCRM GridPro GridPro str 10/8 77/68 338/311 n/a One-to-one
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HL-CRM“committeegrids”
Points/cells
Gridsystems
Label Gridtool Org Type Medium,noN/P
Medium,with N/P
Notes
A-JSM Chimera NASA str 221/216 235/230 Overset
B-JSM DLR-SOLAR DLR unstr 102/162 126/207 Mixed
C1-JSM VGRID Spaceship&Gulfstream
unstr 16/97 21/124 Tet
C1-JSM VGRID Spaceship&Gulfstream
unstr 16/52 21/65 Mixed
D-JSM JAXAtools JAXA unstr 50/120 59/139 Mixed
E-JSM ANSA UOxford&BETA-CAE
unstr 52/107 58/120 Mixed
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JSM“committeegrids”