Aimed at a certain type of horizontal single-stage single-suction centrifugal pump,a 3 dimensions mathematical model was constructed.By using the computational fluid dynamics theory and moving reference frame model and two-phase mixture model to simulate the internal state of the pump,the change rule of the interior pressure,vapor-liquid two-phase and vapor-phase volume fraction with the output frequency and the velocity of pump were obtained.The calculation results show that the inlet pressure has the inve...