Author/Authors :
Horst-MichaelPrasser، نويسنده , , MatthiasBeyer، نويسنده , , HelmarCarl، نويسنده , , SabineGregor، نويسنده , , DirkLucas، نويسنده , , HeikoPietruske، نويسنده , , PeterSchütz، نويسنده , , Frank-PeterWeiss، نويسنده ,
Abstract :
Theevolutionofthestructureofagas–liquidflowinalargeverticalpipeof195mminnerdiameterwasinvestigatedattheTOPFLOWtestfacilityinRossendorf.Wire-meshsensorswereusedtomeasuresequencesoftwo-dimensionaldistributionsoflocalinstantaneousgasfractionwithinthecompletepipecross-section.Thesensorsownaresolutionof3mmatafrequencyof2500Hz.Superficialvelocitieswerevariedinarangecoveringflowregimesfrombubblytochurn-turbulentflow.Thedistancebetweenthegasinjectionandthesensorpositionwaschangedusingaso-calledvariablegasinjectionsystem.Itconsistsofsixgasinjectionunits,eachequippedwiththreeringsofinjectionorificesinthepipewall(orificediameter:1and4mm),whicharefedfromringchambers.Thegasflowtowardsthesedistributorchambersisindividuallycontrolledbyvalves.Measuredbubble-sizeresolvedradialgasfractionprofilesrevealdifferencesinthelateralmigrationofbubblesofdifferentsizestartingfromtheinjectionatthewall.Theevolutionofbubble-sizedistributionsallowstostudybubblecoalescenceandbreak-up.Theinfluenceofthephysicalpropertiesofthefluidwasstudiedbycomparingcoldair–waterexperimentswithsteam–watertestsat65bar.
