PARTIALLY-AVERAGED NAVIER-STOKES MODEL FOR PREDICTING CAVITATING FLOW IN CENTRIFUGAL PUMP

Cavitation is a common phenomenon in pump industries, which leads to severe problems, like vibration and noise. It may degrade the pump performance and even damage the solid surface. So it is significant to give a precise prediction of the pump cavitation performance. The original k-epsilon model is widely used in the past years. However, it is reported that high viscosity of the original k-epsilon model dampens cavitation instabilities and hence makes it difficult to capture the detachment of the bubbles. Aiming at improving the predictive capability, the partially-averaged Navier-Stokes (PANS) is employed in this paper to predict the pump cavitation performance. Experiments on a centrifulgal pump with twisted blades are carried out to validate the simulations. The results show that, compared with the original k-epsilon model, the PANS model with lower f(k) value gives a more accurate prediction and can reduce the eddy viscosity in the cavity region, leading to capturing the unsteady bubble shedding phenomenon. The experimental visualizations are performed and the evolution of the cavitation inception and development are obtained exactly at the impeller inlet. Comparisons with the transient numerical simulations are made, which demonstrates the PANS model can successfully capture the cavitation detachment. Finally, the blade load pressure, the pressure distribution in impeller and the pressure fluctuations are analyzed. Good agreement is noticed between simulations and experiment. So it can be concluded that the PANS model can effectively reduce eddy viscosity in cavitating flow in centrifugal pumps and improve the numerical simulation prediction of pump cavitation performance.