Study On Dynamic Characteristics Of Centrifugal Pump Shaft Coupling Flow Field

Centrifugal pump is the important equipment in auxiliary system. It is also one of the main sources of vibration. In this paper, based on a cruise water centrifugal pump vibration which affects the crew rest, developed the diagnostic process of the response test, pathway analysis,identifying force source. To reduce pump vibration as the goal developed optimization scheme. The specific contents are follows:Finite element simulation and experimental tests of the pump modal is studied. Based on the results of the modal test, modified finite element model obtains the matched better model with frequencies and modes. The possible of pump resonance was excluded.For the response test results, the main interference frequencies are blade and its frequency doubling. For the analysis of flow field which influences blade frequency, a three-dimensional unsteady flow model is established. It is found that the flow field pulsating pressure is too much at the pump cut-water. Reducing the number of blades may increase the flow channel width to reduce pressure pulsation. Considering the size and lift, it proposed to replace the six-bladed impeller scheme. The simulation results show six-bladed impeller can meet the requirements. It improves the unevenness of the flow field, reduces the pressure pulsation,impeller force and torque.For the analysis of the whirling vibration which influences shaft frequency and double shaft frequency, a flow field-shaft vibration coupling model is also established. It analyzed the whirling vibration natural frequency and the shafting vibration influence of the misalignment and unbalance amount. Combination with the engineering practice, a reasonable scheme for increasing accuracy of shaft processing and assembly has been proposed.After replacement of impeller, flow field and shaft system characteristics will change. It is necessary to assess its stability. It analyzed the torsional vibration frequency and response to eliminate resonance. Due to the vibration test is in the vertical pump group, shafting longitudinal vibration caused by the impeller has been analyzed and then the influence on pump.Finally, the load generated by the fluid force, unbalanced force and the misalignment exciting force is applied to the shafting to simulate and developed the experimental verification. The results show that vibration of pump intermediate frequency line spectrum is reduced effectively.