Research on the Cavitation Flow Characteristics and Transport Mechanism of Rotating Cascades

In this study, a numerical simulation combining the Detached Eddy Simulation (DES) model with the Zwart Gerber Belamari (Z-G-B) cavitation model is used, along with a visualization experiment, to analyze cavitation flow within a rotating cascade. The results showed that during the weak cavitation stage, the interaction between cavitation bubbles and vortices affects the energy distribution mechanism within the impeller. The shorter the cavitation bubble shedding time or the smaller the time it takes for a bubble to grow from its minimum to maximum size, the larger the amplitude associated with the main frequency. During the unstable cavitation stage, vaporization at the blade leading edge suppresses bubble shedding, reducing both cavitation intensity and the rotor-stator interaction between the impeller and volute. Furthermore, the formation of migratory cavitation results from two factors: first, severe fluctuations in cavitation bubble morphology caused by changes in the kinetic energy of high-speed fluid; second, complex backflow at the impeller outlet. During the weak cavitation stage, the change in vorticity is mainly influenced by cavitation and the dynamic-static interference between the impeller and volute. During unstable cavitation, vorticity primarily changes due to the cavitation process. As cavitation develops, changes in the morphological shape of the cavitation bubble interface and the vortex motion at its tail are the main factors affecting vorticity transport.