Evaluation of a modified URANS prediction of unsteady cavitating flow around a hydrofoil by comparing with LES results and experimental results. (May 2023) - Zhang, Shijie
Highlights: The interface effect-based correction model (IE model) performs well for unsteady cavitating simulation of a hydrofoil. The IE model modifies the turbulent viscosity in the high shear flow region. The macro flow structures obtained by the IE model are comparable to LES model. The commutating time of the IE model is 14% of the LES cost for the hydrofoil case. Abstract: The research makes the analysis of cavitating flow field around hydrofoil NACA0009 through both experiments and numerical simulations. We previously proposed an interface effect-based correction model (IE model) for turbulent viscosity correction of cavitation flow, which performed well for hydrofoil cavitation simulation at small angles of attack. This research makes a further evaluation of the IE model. Firstly, the cavitation experiments of the NACA0009 blunt trailing edge hydrofoil with a 10-degree angle of attack are carried out on a closed test platform. The images of quasi-periodic shedding of partial cavitation are obtained. Secondly, the standard k-ε turbulence model, the IE model, and the large eddy simulation (LES model) are used to reproduce the cavitation flow around the hydrofoil. The results show that the standard k-ε model over-predicts the turbulent viscosity of the flow field, resulting in the cavitation region stably attached to the leading edge of the hydrofoil, which can't simulate the unsteady characteristics of the cavity bubbles. The LES model successfully reproduces the process of cavitation structure quasi-periodic shedding off. The IE model modifies the turbulent viscosity in the high shear flow region so that the reentrance flow can reach the leading edge of the hydrofoil and cut the attached cavity off. IE model can properly simulate the macro features of the cavity and the shedding frequency. In each stage of cavitation periodic shedding, the results of the IE model and the LES model on the pressure distribution and velocity field are consistent well. In addition, the calculation time cost of the IE model is basically the same as that of the standard k-ε model, only 0.14 times the LES model costs. The IE model is more suitable for cavitation evaluation in engineering applications.