A theoretical model to predict cavitation inception in centrifugal pumps

Abstract

Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.This paper presents a theoretical model for the prediction of the incipient of cavitation in centrifugal pumps. The model includes the physical fluid parameters and the real working phenomena at off-design condition. The parameters considered in the model were flow rate ratio, pump rational speed, water temperature, thermodynamic properties of water, nuclei and gas content, relative velocity and incidence angle. The thermodynamic effect had a more complex expression compared with other parameters. The present model has been tested against extensive earlier published experimental results in centrifugal pumps at wide operating conditions. The comparison of the predicted net positive suction head at inception with the published data showed a good agreement was achieved. This agreement means that the roles played by operating parameters, off-design phenomena and thermodynamic properties of water are consistent with the present model. The results obtained from the present model make it possible to explain why there is a difference between the real net positive suction head values and the theoretical ones in the previous published models. Therefore, the present model could help the pump user and designer to estimate the incipient net positive suction head at various conditions.