Validationofthesub-channelcodeF-COBRA-TF:PartI.Recalculationofsingle-phaseandtwo-phasepressurelossmeasurementsOriginalResearchArticle

Thepresentpaperdealswithrecalculationsofsingle-phaseandtwo-phasepressurelossmeasurementswiththeadvancedtwo-phase,three-fieldsub-channelcodeF-COBRA-TF.Thereby,experimentaldataofboththeOECD/NRCBFBTbenchmarkandin-housetestsinAREVANPʹsKATHYloopareused.Themaingoalofthispaperisnottofocusonaspecialnewmodelorcorrelationbuttogiveanoverviewhowacompletepressurelosscalculationforpracticalpurposescanbecarriedoutbeingbasedonasimplifiedandstraightforwardmethodtoestimatesub-channelspacerpressurelosscoefficientsontheonehandandanadvancedsub-channelcodeontheotherhand. Thepressurelosscoefficientsarecalculatedanalyticallyandcalibratedatavailablemeasurementsoftotalsingle-phasebundlepressureloss.Thus,theyarenotadaptedtoanytwo-phasemeasurementandalsodonotdependonthesub-channelcodetheyareusedin. Theresultsoftherecalculationsofthemeasurementsespeciallydemonstratethecapabilityofathree-fieldcodetopredictbothsingle-phaseandtwo-phasepressurelosseswithhighaccuracy,whereasthecodeisnotbasedonconventionalpressurelosscorrelationsusingtwo-phasemultipliersbutratheroninterfacialfrictioncorrelationsforeachflowregime.Thereby,theF-COBRA-TFstandardmodels–whichareusuallyappliedforallsortsofcalculations(pressureloss,voiddistribution,lateralmixing,criticalheatflux,etc.)–wereused.Itwasnotnecessarytodospecialcodetuningwithrespecttocertainexperiments.