简介：Aerationisanimportantfactoraffectingthebiologicalaerationfilter.Withasetofexperimentdevicespeciallydesignedforthepurpose,andtheparticleimagevelocimetrytechnique,thevelocityfieldofthegas-liquidtwo-phaseflowisstudiedunderdifferentconditions.Thevarioussimulatedaerationstateswereactuallyappliedtotheexperimentaldeviceofsewagetreatment,andtheresultsofthenumericalsimulationwereverified.Thefinalexperimentalresultsindicatethatthemostefficientstateoccurswhentheratioofwaterinaerationtankh/w=1,thediameterofcapillarytubesd=0.6mmandthevelocityofbubblesv=0.3m/s.

简介：Thequasi-2Dmodel,takingintoaccounttheaxialvelocityprofileinthecrosssectionandneglectingtheconvectiveterminthe2-Dequation,canmoreaccuratelysimulatethewaterhammerthanthe1-Dmodelusingthecross-sectionalmeanvelocity.However,ascomparedwiththe1-Dmodel,thequasi-2Dmodelbearsahighercomputationalburden.Inordertoimprovethecomputationalefficiency,the1-Dmethodisproposedtobeusedtosolvedirectlythepressureheadandthedischargeinthequasi-2Dmodelinthispaper,basedonthefactthatthepressureheadobtainedasthesolutionofthetwo-dimensionalcharacteristicequationisidenticaltothatsolvedbythe1-Dcharacteristicequations.Theproposedschemesolvesdirectlythe1-DcharacteristicequationsforthepressureheadandthedischargeusingtheMOCandsolvesthe2-Dcharacteristicequationfortheaxialvelocitiesinordertocalculatethewallshearstress.Iftheradialvelocityisneeded,itcanbeevaluatedeasilybyanexplicitequationderivedfromtheexplicit2-Dcharacteristicequation.Inthenumericaltest,theaccuracyandtheefficiencyoftheproposedschemearecomparedwithtwoexistingquasi-two-dimensionalmodelsusingtheMOC.Itisshownthattheproposedschemehasthesameaccuracyasthetwoquasi-2Dmodels,butrequireslesscomputationaltime.Therefore,itisefficienttousetheproposedschemetosimulatethe2-Dwaterhammerflows.