The wear ring clearance of centrifugal pumps is of significant importance for numbers of effects. In the paper, these effects including the performance, pressure pulsations, hydraulically generated vibration and noise level are investigated. For the purpose, a numerical method combined the FEM and BEM analysis was developed to predict the vibration and sound radiation of the volute. The numerical simulations with and without leakage flow paths being considered were compared. Additionally, the simulation results were validated by the vibration acceleration of the monitoring points on the volute. On this basis, the effects of wear ring clearance were analyzed. The results show that the quality of vibration simulation for centrifugal pumps can be improved by involving the leakage flow paths in simulations. Based on an overall consideration of the performance, pressure pulsations, vibration and noise, the optimum wear ring clearance is supposed to be 0.6 mm for the centrifugal pump (nqSI= 26.7). The results can be used to guide the optimum design of the pump wear ring clearance
