Star-CCM+-风机模拟

UniversityofAppliedSciencesHTWBerlin,FB2Wilhelminenhofstr.75A,12459Berlin,GermanyThermo-&FluiddynamicsgroupProf.Dr.-Ing.StefanFranke-mail:[e-mail],StefanFrankSTAREuropeanConference2011March22-23NumericalInvestigationsonthePerformanceCharacteristicofRadialFanswithForwardCurvedBladesbymeansofCFDAgenda SiroccofanIntroduction◊ Applications◊ Advantages/Disadvantages◊ Characteristiccurves Modelparameters/Modelingphysics CFDSimulationsoutline Rotationmodeling Overviewofthegeneratedmeshconfigurations Results◊ Characteristiccurves:CFDvs.Experiment◊ Simulationtime◊ Steadyvs.Unsteadysimulations Conclusions3CommonlyusedbladeshapesinRadialfans(withtheirmaximumattainableefficiencies)Forwardcurvedblades(65%)Radial-Tipblades(70%)Radialblades(60%)BackwardinclinedAirfoilblades(92%)Backwardinclinedblades(78%)Backwardcurvedblades(85%)Keyfactorsforfantypeselection:◊ Pressure◊ Flowrate◊ Efficiency◊ Noisegeneration◊ Spaceconstraints◊ Driveconfiguration◊ Cost◊ ...4Siroccofanspecifications◊ Largebladeangles◊ Smallsizerelativetootherfantypes◊ Operationatlowspeedslowlevelofnoise Flowseparationbetweentheblades Lowefficiency ScrollhousingisrequiredApplications:− Automotiveindustry− HVACapplications5SiroccoFanPerformanceCurveRegionofInstabilityBestEfficiencyPoint(BEP)ThrottleRangeOverloadRange6ModelParameters◊ Fanwheelouterdiameter(D2):200mm◊ Inner/Outerdiameter(D1/D2):0.8◊ Numberofblades:38◊ Rotorwidth:82mm◊ Scrollhousingwidth:87mm◊ Voluteopeningangle(α):7°ModelingPhysics Idealgas Segregatedflow MassInlet/Pressureoutlet Rotationalspeed:1000rpm Steady-StateMovingReferenceFrame(MRF) RotorPositions:0°,3°,6°7CFDSimulationsoutlineTurbulencemodelsMeshConfiguration Realizablek-ε SSTk-ω Spalart-Allmaras Polyhedral Trimmer Polyhedral-Trimmer StructuredgridCFDSimulationsUnsteady(RigidBodyMotion)Steady-state(MovingReferenceFrame) Polyhedral SSTk-ω8Rotationofcomputationaldomains9 RigidBodyMotion(RBM):ImplicitunsteadyPositionofthecellvertices:MovingInstantaneouslocalflowbehaviorTimeaccuratesolutionTimeconsumingPowerfulcomputerisneeded10 MovingReferenceFrame(MRF):RotationofcomputationaldomainsFrozenRotor(insomeliteratures)Steady-statePositionofthecellvertices:FixedConstantgridfluxgenerationconservationequationsApproximateanalysisofMotion(Time-averagedsolution)TimeefficientMeshconfigurationsConformalInterfaceNon-ConformalInterface11Polyhedral Trimmer Polyhedral-Trimmer Structured Meshgenerator Star-CCM+ ANSYSICEM NumberofCells(inmillions) Total 4.2 6.1 4.0 3.7 Rotor 2.6 4.8 2.7 2.4 Stator 1.6 1.3 1.3 1.3 InterfaceMesh Conformal Non-conformal Non-conformal Non-conformal Meshgenerationtime 2-4hours 5-7days Meshconfigurationscomparison12Meshconfigurationscomparison13Workstation:CPU:IntelCorei7(2.8GHz)RAM:8GBTurbulencemodelscomparison14Turbulencemodelscomparison15Workstation:CPU:IntelCorei7(2.8GHz)RAM:8GBFlowseparationintheNozzleatlowerflowratesNon-uniforminletflow:» DominantflowfieldgeneratedbyRotor» Flowattachmenttooneside&separationfromtheotherside16Steadyvs.unsteadysimulationat675m³/h(Overloadrange)StaticPressureinPaTorqueinNmEfficiencyin%Exp.115.80.50041.5MRF112.60.46043.9RBM114.50.47043.7Steady(MRF)Unsteady(RBM)17Steadyvs.unsteadysimulationat145m³/h(Throttlerange)Unsteady(RBM)Steady(MRF)StaticPressureinPaTorqueinNmEfficiencyin%Exp.1150.10044MRF1260.10148RBM1180.0994618Conclusions Unstructuredmeshconfigurationscanbeusedeffectivelyforsimulatingsiroccofans. Thebestresultsareachievedbyusingpolyhedralcells. ThebestbalancebetweenthesimulationtimeandaccuracyisachievedbyusingPolyhedralcellsaswell. Trimmer(asasinglemesher)isnotsuitableforsiroccofansimulation. SSTk-ωturbulencemodelisthemostsuitablemodelforsimulatingsiroccofans. Atintermediateandhigherflowrates,steady-stateMRFapproachprovidesthesamelevelofaccuracyasunsteadyRBMapproach. Atlowerflowrates,flowbecomeshighlyunsteady,andtheflowconditionisnotsuitedtosteady-stateMRFapproach.19Thankyouforyourattention!