Cavitation Control in Mixed-Flow Pumps through Blade Perforation

During high-speed operation, mixed-flow pumps are susceptible to cavitation, which destabilizes the internal flow, increases energy losses, and degrades hydraulic efficiency. To assess the effectiveness of blade perforation as a cavitation-mitigation strategy, in this study several mixed-flow pump models incorporating perforations were developed. Numerical simulations were performed for configurations with circular holes positioned at different locations along the blade leading edge, and the computational results were validated against experimental measurements. The findings indicate that the location of the perforations plays a decisive role in cavitation suppression. Moving from the blade rim toward the hub along the leading edge, the critical net positive suction head, NPSHcr, initially decreases and subsequently increases, while remaining consistently lower than that of the reference non-perforated configuration. The perforations promote the transfer of high-pressure fluid from the pressure side to the suction side of the blade, thereby alleviating local low-pressure regions. This pressure compensation significantly reduces the extent of low-pressure zones in the vicinity of the perforations, leading to a marked suppression of cavitation both locally and downstream of the perforated regions.