简介:NowadaysComputationalFluidDynamics(CFD)softwareisadoptedasadesignandanalysistoolinagreatnumberofengineeringfields.Wecansaythatsingle-physicsCFDhasbeensufficientlymaturedinthepracticalpointofview.ThemaintargetofexistingCFDsoftwareissingle-phaseflowssuchaswaterandair.However,manymulti-physicsproblemsexistinengineering.Mostofthemconsistofflowandotherphysics,andtheinteractionsbetweendifferentphysicsareveryimportant.Obviously,multi-physicsphenomenaarecriticalindevelopingmachinesandprocesses.Amulti-physicsphenomenonseemstobeverycomplex,anditissodifficulttobepredictedbyaddingotherphysicstoflowphenomenon.Therefore,multi-physicsCFDtechniquesarestillunderresearchanddevelopment.Thiswouldbecausedfromthefactsthatprocessingspeedofcurrentcomputersisnotfastenoughforconductingamulti-physicssimulation,andfurthermorephysicalmodelsexceptforflowphysicshavenotbeensuitablyestablished.Therefore,innearfuture,wehavetodevelopvariousphysicalmodelsandefficientCFDtechniques,inordertosuccessmulti-physicssimulationsinengineering.Inthepresentpaper,Iwilldescribethepresentstatesofmulti-physicsCFDsimulations,andthenshowsomenumericalresultssuchasiceaccretionandelectro-chemicalmachiningprocessofathree-dimensionalcompressorbladewhichwereobtainedinmylaboratory.Multi-physicsCFDsimulationswouldbeakeytechnologyinnearfuture.
简介:Inaclassicallayoutprocessofafanthequantityoflossesisestimatedasasumandexpressedintheoverallefficiencyrateη.Howeverthecharacteristicofthepressurerise,thelossesandtheefficiencyratebesidethedesignpointisnotknown.Againstthisbackgroundanumericalmodelwasdevelopedtocalculatequantitativevaluesofoccurringlossesatradialfanimpellersatanearlystageinthedesignprocess.Itallowstoestimatethepressureriseandefficiencyrateofagivenfangeometryatandbesidethedesignpoint.Thephysicsoflossesaredescribedinliterature,butobtainingquantitativevaluesisstillachallenge.Ascommoninhydraulictheorythelossesarecalculatedwithanalyticformulassupportedbycoefficientsandefficiencyrates,whichhavetobedeterminedempirically.Thispapershowsthemethodhowtodeterminethecoefficientsforagivenradialfan.Thereforearepresentativeradialfanwithbackwardcurvedbladeswasdesignedinreferencetoclassicaldesignguidelines.PerformancemeasuringwasdoneconformtoISO5801.Theflowwascalculatedat8differentoperationpointsusingCFDmethods.TheRANSequationsaresolvedbyusingtheSST-k-omegaturbulencemodel.Theflowdomainconsistsofonebladesectionincludinginletchannelandoutflowchamber.Spatialdiscretizationisdonebyablock-structuredmeshofapprox.1.8millioncells.Performancedatashowaverygoodagreementbetweenmeasurementandcalculation.
简介:一条多维的计算液体动力学(CFD)途径在试图计算一台引擎的转移矩阵的这研究被建议有或没有吝啬的流动处于条件用尽muffler。没有吝啬的流动,有定义为多孔的地区的吸收性的材料的muffler的CFD模型与测量噪音减小被校准,并且进一步被采用在muffler的声学的表演上学习吝啬的流动的效果。而且,exhaust听觉的来源从建议CFD途径以及测量尾巴噪音最不基于multiload获得的六不同另外的声学的负担的计算转移矩阵被导出广场方法。最后,exhaust噪音基于Thevenins定理被预言。建议CFD途径被建议能就吝啬的流动而言预言复杂muffler的声学的表演(没有并且与吝啬的流动)并且加热转移,并且提供exhaust噪音的合理结果。
简介:采用蒙特卡罗和束流光学方法,对反冲质子磁谱仪系统的中子-反冲质子输运及反冲质子在磁场中的偏转和聚焦的全过程进行了物理建模,基于Matlab平台,开发了带电粒子输运模拟计算程序,模拟了反冲质子磁谱仪系统的性能参数,获得了不同参数条件下反冲质子在焦平面上的空间分布、中子能量分辨率及中子探测效率。结果表明,反冲质子磁谱仪的中子能量分辨率和中子探测效率是对立性较强的2个性能参数,主要决定于反冲聚乙烯靶尺寸和反冲质子准直器尺寸,二极分析磁铁的磁感应强度对中子能量分辨率和中子探测效率的影响不大,但会影响反冲质子磁谱仪的紧凑性。对能量为14MeV的氘氚聚变中子,磁谱仪的中子能量分辨率小于1%时,中子探测效率可达10-8cm2。
简介:基于随机介质的谱分解理论,建立了二维多孔介质的细观模型,发展了多孔介质传热问题的多松弛格子Boltzmann方法求解算法,模拟了恒定热流加载下含基体孔隙复合材料的传热过程,计算了碳化硅多孔材料的等效热导率。结果表明,多孔介质的传热过程与孔隙率、孔隙结构密切相关,孔隙率越大材料传热性能越差,等孔隙率条件下,多孔介质沿某一方向的等效热导率随该方向孔隙自相关长度的增加而变大。