Numerical Analysis and Experimental Investigation of Cavitating Flows Considering Thermal and Compressibility Effects

Abstract

This article deals with the numerical simulation of unsteady cavitating flow around hydrofoils, supported by experimental research realized in a cavitation tunnel situated in the Centre of Hydraulic Research. Two straight NACA hydrofoils (NACA0020 and NACA2412) were employed. The comprehensive unsteady CFD analysis was based on scale-resolving simulations (hereinafter SRS) with the aim of capturing correctly the interactions between the cavitation structures and re-entrant flow as well as the compressibility and thermal effects of cavitation. The static pressure fluctuations during the cavity oscillation cycles and the evaporation and condensation processes are discussed in detail. To predict correctly the high-pressure peaks during the bubble cloud collapses and the pressure pulse propagation speed, the real properties of water and the mixture total energy conservation equation were considered. In addition, the estimated content of undissolved air was taken into account. The numerical simulations were validated by means of already published experiments or compared with experiments conducted by the authors, and with good agreement.

Multiphase Flow Simulation of ITTC Standard Cavitator for Underwater Radiated Noise Prediction

“…The scope of the paper is to obtain a better understanding on the main issues underlying cavitation tunnel experiments in an attempt to propose possible solutions of practical interest. In detail, the sound field of an ITTC standard cavitator model in a cavitation tunnel is predicted by solving Lighthill's acoustic analogy with a Finite Element Method (FEM) formulation, where the sources of sound are detached by two multiphase flow simulations based on the homogeneous mixture model-Volume of Fluid (VOF) method [10][11][12][13][14][15][16][17] and the Euler-Euler (EE) approach [18]. Starting from the computation of the sound pressure level in the free field, and assuming spherical spreading without absorption, Computational Fluid Dynamics (CFD) and Computational Hydroacoustics (CHA) allows the definition of an equivalent sound pressure level that accounts for corrections due to acoustic spreading and losses, whereas a devoted FEM analysis of the tunnel yields information on teh vibroacoustic effects on wall-mounted sensors.…”