Experimental and numerical analysis of tip leakage cavitating flow around a 3D NACA66 (mod) hydrofoil

Combined experimental and numerical methods, the objective of this paper is to investigate the characteristics of the cavitating flow around a 3D NACA66 (mod) hydrofoil, especially for the tip leakage cavitating flow. The cavitating flow is divided into three patterns: (I) mainstream cavity (MC); (II) mainstream cavity and tip leakage vortex cavity (MC&TLVC); (III) mainstream cavity, tip leakage vortex cavity and film bridge cavity (MC&TLVC&FBC). The changing laws of the three patterns are related to the attack angle α and cavitation number σ. The LES turbulence model and Schnerr-Sauer cavitation model are implemented in the numerical simulations, whose results show good agreement with the experimental data. For the typical condition of α = 8°, V_∞ = 10 m/s, σ = 1.5, the characteristic frequencies of TLVC and FBC are 35 Hz and 37 Hz, respectively, which are very close to the shedding frequency of MC (36 Hz). By analyzing a typical shedding cycle, the mainstream is proved to have a decisive influence on the tip leakage cavitating flow.