Gas–liquidphasedistributionandvoidfractionmeasurementsusingMRIOriginalResearchArticle

Weusedapermanent-magnetmagneticresonanceimaging(MRI)systemtoestimatetheintegral,spatially-andtemporally-resolvedvoidfractiondistributionsandflowpatternsinverticalgas–liquidtwo-phaseflow.Airwasintroducedatthebottomofthestagnantliquidcolumnusinganaccurateandprogrammablesyringepump.Theairflowratewasinupwardverticaldirectionagainstthegravityvector.Airflowrateswerevariedbetween1and200ml/min.Bubbleformationanddetachmentattheinletoftheverticalcolumnwasnon-uniform.Thecylindricalnon-conductingtesttubeinwhichtwo-phaseflowischaracterizedwasplacedina0.26Tpermanent-magnetMRIunit.Aroughlylinearrelationshiphasbeenobservedfortheintegralvoidfractionversusvolumeflowrateofairthroughverticalstagnantliquidcolumn.Integralorsample-averagedvoidfractionwasobtainedbyvolume-averagingofthespatially-resolvedsignals.Spatialaveragingwasperformedinaradialorlongitudinalaxisofthecolumn.Thetime-averagedspatially-resolvedvoidfractionhasalsobeenobtainedforthequasi-steadyflowofairinastagnantliquidcolumn.Nogreataccuracyisclaimedasthiswasanexploratoryproof-of-concepttypeofexperiment.PreliminaryresultsshowthatMRIcanindeedprovidequalitativeandquantitativedataandisespeciallywellsuitedforcharacterizationofaveragedtransportprocessesinadiabaticanddiabaticmulti-phaseand/ormulti-componentflows.BetterandfasterMRIsequencescouldimprovespatialandtemporalresolutionssignificantly.