Computational Examination of Unsteady Cavitating Flow Characteristics on a 2D NACA66 Profile by Utilizing OpenFOAM®

Abstract

The complexity of the flow mechanism is one of the crucial problems in cavitation. In this present study, detailed computational examinations of cavitating flow around a NACA66 hydrofoil were performed by using OpenFOAM® software. Dynamic and unsteady behaviours of cavitating flow were solved utilizing the k-ω SST turbulence model. Schnerr-Sauer cavitation model was used for the calculations. Numerical simulations were performed for 6° and 8° angle of attack with different cavitation numbers and the outlet pressure conditions, the cases are called “Case 1” and “Case 2” respectively. The results were compared with the studies performed by Leroux et. al. Oscillation cycles and flow characteristics were obtained successfully in both cases. The mechanism called the re-entrant jet was shown to be primarily responsible for cavitation break-off in two cases. This mechanism consists of two steps: 1) an interplay between the re-entrant flow and the cavity contact surface in the occlusion region, resulting in recurrent secondary cloud shedding until the primary cloud detachment, and 2) a shock wave triggered by the primary cloud collapsing, which affects the development of the remnant cavity.
 The main contribution of this study is to examine the impact of using the k-ω SST turbulence model with the Schnerr-Sauer cavitation model on predicting flow characteristics such as cavitation dynamics, pressure distribution and cavity form. Acceptable accuracy has been observed for pressure fluctuations and cavitation dynamics.