Dynamical Analysis Of Multistage Centrifugal Pump And Investigation Of Fault Diagnosis

The vibration of a new multistage centrifugal pump is severe. To judge the problemwhich was caused by the design or manufacturing, in this thesis the force source units,pathways and responses of the machine were analyzed in detail. It was sure that the problemwas not caused by resonance between shafting and incentive after calculating shaftingdynamics and machine dynamics. Basing on spectrum analysis techniques, the fault of theisolator installing was diagnosed. Also, the contact—rubbing fault of the impeller was foundwith the method of force source identification. After dismantling and examining the machine，It was found that the problem was the discrepancy of impeller machining and drawings. Themain contents in this thesis:Firstly, the whirling vibration of the rotor-bearing system was calculated based on thefinite element method. The first three resonance rotating speeds, forward and whirlingcondition of whirling vibration was obtained, according which to determine whetherresonance existed and predict whether the fault occurred when resonance occurred.Secondly, according to empirical formula, the longitudinal force of fluid in the pump wasforecasted. Loaded the longitudinal force on every impeller, and longitudinal vibrationdisplacement of every node along the rotor axial and the stress distribution between the shaftsegment were calculated based on centralized parameter method. And then determine whetherfault would occur in the design of the pump shaft.Thirdly, the FE model was built and the loads at the bearing caused by fluid were loadedon the FE model. the force response was obtained which is consistent with designing value.The vibration of the centrifugal pump unit is not severe. So far the possibility of design faultin the pump is basically removed.Then, according to testing data, fault diagnosis for a certain type of fault centrifugalpump was down in this thesis. The vibration of the pump was reduced initially throughmodified the isolator installation location and reduced the vibration difference caused byisolator installation imbalance. As the vibration was still excessive, more deeply analyzed onfailure mechanism was down. The possibility of the failure of bearing was excluded aftercalculating the nature frequency of the bearing. Then, through the load identificationtechnology, the internal force of the fault pump unit was calculated. Combined with the forceof normal state, it can be concluded the fault occurred at the first level impeller and causedlarger fluid excitation.Finally, it was really found that the first level impeller had problems after overhauling the pump unit. The conclusion of fault diagnosis was verified and the process of faultdiagnosis for centrifugal pump was obtained.