Oscillation Caused by Vortex Cavitation in a Double-Suction Volute Pump

This study highlights a mechanism of the vortex cavitation occurrence from the baffle plate, the end of the suction duct, in a double-suction volute pump and a relationship between pump oscillation and the cavitation occurrence. In this study, full 3D numerical simulations have been performed using a commercial code inside the pump from the inlet of suction duct to the outlet of delivery duct. The numerical model is based on combination of multiphase flow equations with the truncated version of Rayleigh-Plesset model predicting the complicated growth and collapse process of cavity bubbles. The vortex cavitation has the characteristic frequency based on the impeller rotation and has much influence on the pump oscillation, however at over discharge range the vortex cavitation does not collapse, because the cavitation runs into and combines with another cavitation generated in the impeller shroud, and the fixed frequency of the pump oscillation is reduced. The experimental investigations have also been performed on the cavitating flow to evaluate the numerical results and the both results agree well.