Unsteady cavitation dynamics and pressure statistical analysis of a hydrofoil using the compressible cavitation model

Abstract

A compressible cavitation model is developed in this paper, in which the bubble wall velocity is obtained by solving the compressible Rayleigh–Plesset (R–P) equation. Additionally, vapor compressibility is also included during evaporation/condensation to correct the phase change rate. The predicted results around a National Advisory Committee for Aeronautics (NACA) 66 (mod) hydrofoil are compared with the available experimental data, and a satisfied agreement is obtained. By (mod), we mean the NACA 66 hydrofoil modified by Brockett [“Minimum pressure envelopes for modified NACA-66 sections with NACA a = 0.8 camber and BuShips type I and type II sections,” Technical Report No. 1780 (David Taylor Model Basin Washington DC Hydromechanics Lab, 1966)] and Valentine [“The effect of nose radius on the cavitation-inception characteristics of two-dimensional hydrofoils,” Technical Report No. 3813 (Naval Ship Research and Development Center, 1974)]. Several crucial flow properties, e.g., fluid compressibility, cavitation evolution features, and pressure statistical characteristics, are studied in detail. The results suggest that the developed compressible cavitation model is better suited for predicting the collapse behavior of cavitation. Moreover, our work captures the liquid re-entrant jet and bubbly shock waves well and reveals that these two mechanisms jointly dominate the cavity shedding dynamics. Shock-induced pressure pulses play a more important role in flow features, with a maximum amplitude exceeding 200 kPa, significantly larger than the pressure pulse caused by liquid re-entrant jets. Finally, the statistical analysis indicates that the pulsating pressure presents non-Gaussian nature with positive skewness, and shock waves exhibit high-frequency and high-energy characteristics.