不同温度水体空化水动力脉动特性的试验研究

第50卷第8期2014年4月机械工程学报JOURNALOFMECHANICALENGINEERINGVol.50No.8Apr.2014DOI：10.3901/JME.2014.08.174不同温度水体空化水动力脉动特性的试验研究*时素果1,2王国玉1胡常莉1高德明1(1.北京理工大学机械与车辆学院北京100081；2.北京机电工程研究所北京100074)摘要：为研究热力学效应对空化水动力脉动特性的影响，采用试验的方法研究温度为279K、298K和318K时绕水翼的非定常空化流动特性。试验在闭式水洞中进行，采用高速摄影的方法观察不同温度下绕水翼的空穴形态，采用测力系统测量水翼受到的升阻力，并对升力信号进行频谱分析，得到水翼升力在非定常空化阶段的频率特征。结果表明，相同空化数条件下，随着温度的升高，平均升阻力系数降低，升力系数波动程度降低；温度对升阻力系数的影响随着空化数的升高而降低。在不同的空化发展阶段下，温度对升力系数影响的规律不同，空化形成和片状空化阶段，温度对升力系数影响较小；云状空化阶段，温度对升力系数影响较大。之所以出现上述规律是因为在同一空化数下，随着温度的升高，空化区域减小；而空化区域越大，温度对空化流动的影响则越大。关键词：热力学效应；温度；空化；动力特性；频率中图分类号：TV131ExperimentalStudyonHydrodynamicCharacteristicsofCavitatingFlowsaroundHydrofoilunderDifferentWaterTemperaturesSHISuguo1,2WANGGuoyu1HUChangli1GAODeming1(1.SchoolofMechanicalandVehicular,BeijingInstituteofTechnology,Beijing100081;2.BeijingElectro-MechanicalEngineeringInstitute,Beijing100074)Abstract：Inordertostudytheinfluenceofthethermaleffectonhydrodynamiccharacteristicsofcavitatingflows,theunsteadycavitatingflowsaroundaClark-yhydrofoilunder279K,298Kand318Kconditionsarerespectivelyinvestigatedexperimentally.Experimentsarecarriedoutinarectangulartestsectionofacavitationtunnel.Ahigh-speedvideocameraisusedtovisualizetheunsteadycavitatingflowpatterns,andtheliftanddragcoefficientsaremeasuredbydynamicsforcemeasurementsystem.Thespectralanalysisofthemeasureddataisconductedandthespectrumcharacteristicoftheliftforcearoundthehydrofoilisobtained.Theresultsshowthatwhenthewatertemperatureisincreased,theaveragevaluesofliftanddragcoefficientsdecreaseaswellastheliftfluctuationtendstobemildbykeepingthecaviationnumberconsistent.Theinfluenceontheliftanddragcoefficientsbytemperaturesbecomesweakenwithincreasesofthecavitationnumber.Thefluctuatingscaleoftheliftcoefficientiscorrelatedtotheunsteadycavityclosely.Thetemperaturehaslittleeffectonthefrequencyofliftwhenitiscavitationinceptionorsheet.Butwhencloudcavityappears,thetemperaturegreatlyaffectsonthefrequencybasedonlift.Tointerprettheconclusionsabove,itisinferredthatwhencavitationnumberisconsta