Mechanism of cavitation suppression in rotating flows: Modulating vapor evolution via vortex design method

Abstract

As a crucial energy equipment, the highly efficient and stable comprehensive hydraulic performance of the mixed-flow pump has made it a focal point of research in the field of fluid engineering. However, cavitation is easily induced due to the complex multi-scenario operating environments, while the complexity of rotating turbulence can exacerbate the cavitation instability. Consequently, a vortex design method based on the potential flow function theory is developed to achieve mesoscale modulation of cavitation inside mixed-flow pumps. Based on current high-precision numerical simulations, primary conclusions are drawn as follows: vortex design strategy significantly enhances the anti-cavitation performance of the pump: compared with the original impeller, the critical net positive suction head for scheme 2 (S2) impeller under the forced vortex design and scheme 3 (S3) impeller under the compound vortex design decreased by 0.33 and 0.47 m, respectively. From the perspective of flow control mechanisms, the decreased blade curvature of S2 effectively reduces the low-pressure region on the suction side, suppressing the disturbance mechanism of vapor on the mainstream and the cavitation development. Furthermore, S3 optimizes the blade leading edge profile and reconstructs the local pressure gradient, not only significantly decelerating the cavitation growth, but also effectively attenuating the turbulent energy dissipation induced by cavitation.