基于ANSYS-CFX-的噪音分析ppt课件.ppt

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1、OVERVIEWOFNOISECAPABILITIESINANSYSCFXThabetBelamriANSYSCanadaLtdOctober2006OutlineNoisemodelingbackgroundLighthillacousticanalogyFfowcsWilliamsandHawkingsmodelLowsonModelANSYSCFXnoisecapabilitiesAdvanceturbulencemodellingNearfieldapplications:automotive,turbomachineryFarfieldappl

2、ications:turbomachineryNoisesourcestrengthcalculationConclusionsNoisemodelingbackgroundJetNoiseinafreefieldatrestDensityPressureSpeedofsoundFarfromthejet,pressureperturbationWaveequationLighthillacousticanalogyNoisemodelingbackground(1)Continuity(2)MomentumLighthillacousticanalog

3、yNoisemodelingbackground(4)LighthillacousticanalogyNoisemodelingbackgroundLighthillTensorReynoldsTensorCompressivestressTensorViscousstressTensorLighthillacousticanalogyNoisemodelingbackgroundPhysicalmodelMathematicalmodelFfowcsWilliams&HawkingsmodelNoiseModelingBackgroundmonopol

4、esourceSelfnoiseinteractionnoisedipolesourceSelfnoisequadrupolesource++FfowcsWilliams&HawkingsmodelNoiseModelingBackground-Lowspeedmachines:TipMachnumber<0.35HigherMachnumberLessaccuracy-Forceactingasapunctualforceonthegravitycentre-Smallbladespan-UsageofSemi-empiricalcoefficien

5、ttodefinetheloadingdecay(loadingcoefficient)LowsonmodelModelassumptionsNoiseModelingBackgroundh:Loadingcoefficient=(2.0-2.5)UnsteadyforcecomponentsM:Machnumberz:Bladenumber:Rotationalspeed[rd/s]steadyforcecomponents:Fx0andFy0:HarmonicmodeJn:BesselfunctionofnthorderLowsonmodelA

6、cousticpressureforthemthharmonicNoiseModelingBackgroundSoundpowerforthemthharmonicAcousticpressureforthemthharmonicSoundpressurelevelsin[dB]:Soundpowerlevelsin[dB]:LowsonmodelFx0andFy0areobtainedfromasteadystatesolutionBladepassageanditsharmonicsANSYSCFXNoiseCapabilitiesCFDSteady

7、/TransientsimulationsCFDPredictionsofAcousticsourcesNoiselevelsattheobserverpositionSysnoiseTurboNoiseFarfieldNearfieldANSYSCFXNoiseCapabilitiesNearfieldCalculation(Pseudosound)-AccurateTransientdatafromCFD-AdvanceturbulencemodellingFarfieldcalculation-TurboNoisemacro(Lowsonmodel

8、)-InterfacetoFarfieldCodes(Sysnoise,inho