Numerical Simulation of Unsteady Flow in A Centrifugal Pump

Abstract

In this paper, the computational fluid dynamic (CFD) method was used to simulate the three-dimension, unsteady turbulent flow in a primary pump. Moving mesh method was used to simulate the rotation of the impeller. Sufficient monitoring points in the impeller channel, diffuser channel and interaction zone are set to get the instantaneous pressure. Fast Fourier Transformation (FFT) method was used to get the fluctuation frequency and amplitude. Steady and unsteady calculations were carried out in small and nominal flow rates. Unsteady flow in the flow channel at off design condition was revealed. The vibration frequency variation of the pump in different flow rates was analysed. The pressure fluctuation amplitude in different positions of the pump was shown. The results showed that in the clearance between impeller and diffuser, it has the largest fluctuation and higher frequencies. The fluctuation transports downstream. In off design flow rate, the pressure fluctuation is larger than in nominal flow conditions. The dominant frequency is 1 BPF in small flow rate and 3 BPF in large flow rate. The pressure fluctuation happened in the pump is caused by the stator-rotor interaction. This is clearly shown in the internal flow field.