离心泵蜗壳内非定常流动特性

第33卷第11期振动与冲击JOURNALOFVIBRATIONANDSHOCKV01．33No．112014离心泵蜗壳内非定常流动特性王松林，谭磊，zZ)~l(1．华北水利水电大学水利学院，郑州450011；2．清华大学水沙科学与水利水电工程国家重点实验室，北京100084)摘要：基于修正的RNGk—湍流模型和输运方程空化模型，对离心泵内部非空化和空化的非定常流动进行了数值模拟，计算结果与试验结果吻合较好，验证了数值模型和计算方法的准确性。在离心泵蜗壳内布置了5个监测点，分析了蜗壳内非空化和空化工况时流动特性。结果表明：离心泵非空化和临界空化工况下，蜗壳内压力脉动的主频为叶片通过频率145Hz或290Hz，而在充分发展空化工况下，压力脉动的主频非常低，可能原因是空泡剧烈的脱落及溃灭引起的。三种工况下，离心泵蜗壳第2断面附近的压力脉动最大幅值均远大于其它监测点，原因是此处存在较强的二次流，出现了两个非对称反向旋涡，两个旋涡的涡心位置、形状、强度随时问不断变化，对流动产生较强扰动，诱发强烈的压力脉动。关键词：离心泵；蜗壳；非定常；流动特性中图分类号：TH311文献标志码：ADOI：tO．13465／j．cnki．jVS．2014．11．008CharacteristicsofunsteadyflowinacentrifugalpumpvoluteWANGSong—lin，TANLei，WANGYu—chuan(1．SchoolofWaterConservancy，NorthChinaUniversityofWaterResourceandElectricPower，Zhengzhou450011，China；2．StateKeyLaboratoryofHydroscienceandEngineering，TsinghuaUniversity，Beijing100084，China)Abstract：TheunsteadyflowinacentrifugalpumpwasnumericallysimulatedbyusingcombinationofthemodifiedRNG一turbulencemodelandthetransportequationcavitationmode1．Theagreementbetweentheexperimentalresultsandthesimulationoneswassatisfactory，itdemonstratedthatthenumericalmodelandthecalculationmethodscanbeusedtoaccuratelypredictthecavitationflowinacentrifugalpump．Theflowcharacteristicsinacentrifugalpumpvolutewithoutandwithcavitationwereanalyzedbysetting5monitoringpointsinthevolute．Itwasshownthatthedominantfrequenciesofpressurefluctuationinthevoluteatoperatingconditionsofnon—cavitationandcriticalcavitationarethebladepassfrequencyof145Hzor290Hz；however，thedominantfrequencyofpressurefluctuationatthedevelopedcavitationconditionisverylowduetotheviolentsheddingandcollapseofbubblesinthepump；forthreeoperatingconditions，themaximumamplitudeofpressurefluctuationatthesecondsectionofthevoluteismuchlargerthanthoseatothersections，thepossiblereasonisthatthereisastrongsecondflownearthissectioninducedbyapairofcounter-rotatingvortex；thelocation，shapeandstrengthofthevortexarechangingwithtime，thischangingvortexdisturbstheflowinthesecondsectionandleadstostrongpressurefluctuations．Keywords：centrifugalpump；volute；u