Cavitation erosion in Venturi pipe and erosion optimization of four-stage pump

Cavitation erosion is a prevalent and challenging phenomenon in hydraulic machinery, which can cause flow-induced failure. In this study, we investigate the mechanisms and mitigation of cavitation erosion through a combined experimental and numerical approach. High-speed visualization experiments were conducted in a Venturi-type pipe to capture the transient evolution of cavitation structures and correlate them with erosion-prone regions. Simultaneously, numerical simulations based on the large eddy simulation (LES) method coupled with a volume of fluid (VOF) model were used to resolve the cavitating flow field. A local erosion aggressiveness indicator was developed to quantitatively evaluate cavitation-induced material damage. The proposed erosion prediction model is verified against the experimental results, and the erosion attributes of the specimens are investigated under varying expansion angles. The findings indicate that the formulated cavitation prediction model adeptly delineates the distribution characteristics of cavitation across the surface of the specimen. Under conditions of constant flow rate, there is a discernible decline in cavitation intensity concurrent with the augmentation of the expansion angle. Building on this observation, a numerical simulation is conducted to examine the cavitation erosion in a four-stage high-pressure circulating pump. By increasing the diffusion angle of the leading-edge twisted blades, the cavity distribution is altered, resulting in an increased distance between the cavitation bubble collapse center and the blade surface. This adjustment reduced the impact of pressure waves on the blade surface, thereby mitigating the risk of cavitation erosion.