Numerical investigation of cavitation-vortex interaction around the NACA66(mod) hydrofoil with emphasis on multistage shedding process

The objective is to investigate an observed multistage shedding process of cloud cavitation around a NACA66 (mod) hydrofoil with emphasis on the flow structure and the interaction of cavitation and vortex. The LES method combined with the Schnerr-Sauer cavitation model in OpenFOAM is applied to capture the details of the cavitating flow. For the primary shedding process, the Q criterion exhibit that the interaction between the circulating flow and the shedding cavity is closely related to the complex vortex structure. The shedding cavity under the combined effect of flow and vortex sequentially go through the stages of aggregation, U-shape structure, double C-shape structure and finally collapse. For the secondary shedding process, a small-scale cavity is detached under the influence of primary shedding cavity and vapor structures, with more significant fluctu-ation of lift coefficient. The results of the omega criterion indicate that shear flow plays a major role in the non -cavitation region between the shedding structure and the attached cavity during multistage shedding, and rotational flow dominates in the vicinity of the cavity.