We are comparing results of numerical simulations against high-speed simultaneous observations of cavitation and cavitation erosion. We performed fully compressible, cavitating flow simulations to resolve the formation of the shock waves at cloud collapse—these are believed to be directly related to the formation of the damage. Good agreements were noticed between calculations and tests. Two high pressure peaks were found during one cavitation cycle. One relates to the cavitation collapse and the other one corresponds to the cavitation shed off, both contributing to a distinctive stepwise erosion damage growth pattern. Additional, more precise, simulations with much shorter time step were performed to investigate the processes of cavitation collapse and shedding off in more detail. There the importance of small cavitation structures which collapse independently of the main cloud was found. The present work shows a great potential for future development of techniques for accurate predictions of cavitation erosion by numerical means only.

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-ε model is widely used in the past years. However, it is reported that high viscosity of the original k-ε 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-ε 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.

(2014). Corrigendum. Engineering Applications of Computational Fluid Mechanics: Vol. 8, No. 3, pp. 476-476.