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1、上海交通大学工学硕士学位论文摘要翼分别减阻力7.02%和6.7%。在近场，简单增展机翼能够使翼尖涡远离机翼，而翼梢小翼不仅如此，还能将较强翼尖涡分散成强度降低的涡。在远场，小翼和简单增展机翼都没能加快翼尖涡消散。关键词：自由曲线，翼梢小翼，翼型，全局优化，分级优化，涡格法，CFX第II页万方数据上海交通大学工程硕士学位论文ABSTRACTOptimalDesignofWingletModeledbyFreestyleCurveABSTRACTApplicationofwingletontransportwillleadtoimp
2、rovementofaerodynamiccharacteristicsforitisabletoreduceinduceddragofwing.However,WingRootBendingMoment(WRBM)willalsoincreaseduetothewinglet,andthenthestructureofwinghastobeadapted.NURBScurvecontrolledbyalotofnumberisabletofromvariousforms,thusitissuitformodelinganove
3、lwinglet.Airfoilusedinthemodelofwingletshouldbeselectedparticularlyforithaslargeeffectontheperformanceofwinglet.Besides,thecalculatingmethodandstrategiesofoptimizationusedinoptimaldesignhavedirectinfluenceontheresults.Thedesigntargetoftheoptimizationofwingletmodeledi
4、nthispaperistoreducethedragofwingwithwinglet,whichsubjectstotheconstraintthatthepercentofincreaseofWRBMshouldbelessthan5%,andthedesignstatusiscruisephaseofcommercialaircraft.Firstly,thecriteriaofchoosingsuitableairfoilissetupaccordingtothefeatureofwinglet,andthenagoo
5、dairfoiliscarriedoutbyHicks-Hennefunctionmethod.Secondly,surfacemodelofwingletisestablishedbycoupleoffreestylecurvebasedonNURBSandairfoilchoseinCATIA.Thirdly,consideringthatVortexLatticeMethod(VLM)isafastmethod,CFXisofhighfidelity,globaloptimizationisabletosearchinla
6、rgescale;stratifiedoptimizationcanreducetheamountofcalculation,thispaperputthemintotwostrategies:GlobalOptimizationbasedonVLMandStratifiedOptimizationbasedonCFX.Tomakesomecomparison,stratifiedoptimizationbaseonVLMisalsoadoptedinOptimizationofwinglet;GlobalOptimizatio
7、nbasedonVLMwiththeconstraintoftrailingedgeinsmallrangeisalsoconducted.Finally,theflow第III页万方数据上海交通大学工程硕士学位论文ABSTRACTfieldofwingletandsimpleextensionofwingwithsamespanareanalyzedandcomparedtofigureoutthemechanismofwingletreducingdrag.Theresultsindicatethat：Wingletsdes
8、ignedinthispaperviadifferentmethodsandstrategiesachievelargereductionofdrag,particularlywingletdesignedbyglobaloptimizationwithcons
