《流体引起的振动》PPT课件.ppt

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1、Flow-InducedVibration流体引起的振动Flow-InducedVibration流体引起的振动Unlikemanyoftheothermechanicalvibrationproblemssuchasunbalance,misalignment,resonanceandsoforth,flow-inducedvibrationisoftenverydependentuponoperatingconditions.Thatis,itcanbeveryaffectedbyloaddependingonthetypeofmachineandth

2、eworkbeingperformedbythemachine.与不平衡、不对中和共振等许多问题不同，流体引起的振动往往与设备的工艺运行状态密切相关。这就是说，依照设备类型的不同，设备的负荷以及设备承担的工艺角色对振动的影响会很大。FlowRelevantFaults流体相关故障Flow-inducedvibrationincludeseachofthefollowing:•HydraulicandAerodynamicForces•CavitationandStarvation•Recirculation•FlowTurbulence•Surge•Cho

3、king流体引起的振动包括以下几种情况：流体动力气蚀和抽空回流紊流喘振流体堵塞HydraulicandAerodynamicForces流体动力Varioustypesofmachinesincludingpumps,blowers,turbines,vacuumpumpsandsoforthinherentlyproducehydraulicoraerodynamicforcesastheirimpellersimpartworkonthefluid(liquidorgaseous)theyarehandling.Ingeneral,hydraulica

4、ndaerodynamicforcesaregeneratedasperthefollowingequation:Blade(orVane)PassFrequency=BPF=#VanesXImpellerRPM(CPMorHz)很多类别的设备，包括泵、风机、透平机、真空泵等等，均会不可避免地因为它们的叶片作用在输送的流体（液体或气体）上而产生流体动力。一般，流体动力的产生遵从下面的等式：叶片通过频率＝BPF＝叶片数x叶轮转速（cpm或Hz）Blade&VanePassFreq叶片通过频率Hydraulic&aerodynamicforcevibratio

5、n流体动力振动的特点1.Significantvibrationbothatbladepassfrequencyandbladepassharmonicswillbegeneratedifanimpellerisnotcentrallylocatedwithinitshousingandproperlyalignedwithdiffusers.若叶轮在机壳中偏心或相对于蜗壳的位置不正确，会产生较大的BPF及其倍频的振动。2.Itisimportanttoensurethatneitherthebladepassfrequencynorbladepassha

6、rmonicscoincidewithnaturalfrequenciesoftherotororsupportstructure.Excessivevibrationcanresultifallowedtodoso.需要尽力避免BPF及其倍频与转子或支撑结构的固有频率临近，否则会引起较大的振动。Hydraulic&aerodynamicforcevibration流体动力振动的特点3.Agreatincreaseinbladepassfrequencywilloccurifweldssecuringdiffuservanesexperiencefailu

7、reallowingthediffuserstoshiftpositionslightlyrelativetotheimpeller.若导叶片的焊接处发生失效，使扩压器相对叶轮产生轻微位移，它会导致BPF频率处的振动大幅上升；4.Agreatincreaseinbladepassvibrationwillbecreatedifapumpimpellerwearringseizestotheshaft.若泵口轮摩擦轴，会导致BPF频率振动的大幅上升；5.Bladepassfrequencyinsomeparticularfantypesisparticula

8、rlysensitivetodampersettings.对有些类