Effect of the Volute Diffuser Shape on Pressure Pulsations and Radial Force in Centrifugal Pumps

Centrifugal pump is a major cause of pressure perturbations in hydraulic installations. The internal geometry of this turbomachine and its running conditions affect excessively the magnitude of these excitations. In the present study, a numerical investigation is conducted to analyze the influence of the volute diffuser type on flow characteristics in centrifugal pumps with the same impeller under wide range of flow rate. An unsteady numerical analysis was carried out in order to study the strong interaction between blade and tongue with two different geometries of the volute. The main objective is to analyze the characteristics of pressure and force fluctuations inside the pump. For tangential diffuser shape, the pressure fluctuation amplitudes are greater than that in the case of a radial diffuser. Based on the fast Fourier transform (FFT), the spectral analysis was performed on the pressure fluctuation signals in frequency domain under running condition for two volute at different monitoring points in the pump. The time frequency characteristics of these pressure fluctuations were affected greatly by both volute type and measurement locations in each diffuser. However, simulation results were compared with the available experimental data, and an acceptable agreement was obtained. The results obtained in this work can provide a useful reference for designing the type of volute diffuser in pump.