近壁方柱绕流湍流场非定常特性的PIV实验研究

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1、上海交通大学硕士学位论文近壁方柱绕流湍流场非定常特性的PIV实验研究姓名：万津津申请学位级别：硕士专业：动力机械及工程指导教师：刘应征20090101上海交通大学硕士学位论文ABSTRACTPIVmeasurementofunsteadycharacteristicsofthewakebehindasquarecylinderplacedneartoaplanewallABSTRACTBecauseofthepracticalimportanceandthewealthofinterestingfluidflowphenom

2、ena,muchprogresshasbeenmadeinunderstandingoftheflowaroundasquarecylinderplacednearawall.However,duetoitsphysicalcomplexity,theexperimentalresultsofunsteadycharacteristicsandacompleteandconclusiveexplanationofthephysicsarestilllacking.Theuseofadvancedtechniquesinexp

3、erimentsanddatapost-processingmethodologieshasmadeitpossibletoenhanceourknowledgeofthephenomenon.Inthepresentwork,detailedresultsoftimeaveragedflowpropertiesaswellasunsteadyflowcharacteristicsinthenearwakeofasquarecylinderwithsidelengthDplacednearawallaremeasuredin

4、alow-speedwatertunnel.Particleimagevelocimetry(PIV)andtime-resolvedparticleimagevelocimetry(TR-PIV)measurementsareconductedforcylindertowallgapheights,G,fromG/D=0.1toG/D=1.0.ThePIVmeasurementsobtainsometime-meanresultssuchasvelocityfield,recirculationlengthandshear

5、stressdistribution.AccordingtothecomparisonoftheseresultsindifferentkindsofG/D,theinfluenceofwallproximityonvortexsheddingandflowcharacteristicsinthewakeisclarified,aswellasacriticalgapheightof0.3Disdeduced.For0.3

6、egapheightdecreasing.Belowthecriticalgapheightof0.3D,periodicvortexsheddingisfullysuppressedinthelowersurfaceofthesquarecylinder.TheTR-PIVmeasurementsshowthevortexsheddingandtransformationprocess,bywhichtheperiodiccharacterofthevortexsheddingisrevealed.Theapproacht

7、odeterminepressurefieldfromPIVvelocitydataisalsodiscussedinII上海交通大学硕士学位论文ABSTRACTthepresentwork.ThemethodreliesupontheapplicationofcontrolvolumeapproachincombinationwiththediscretizationofNavier-Stokesequation.Byconsideringlaminarandturbulentflowconditions,differen

8、tialgoverningequationsaresimplifiedanddiscretizedbyfinitedifferencemethodandcirculationmethodrespectively.Thenthereliabilityofpressurepredictiona