CFD Computation of Water Injection on Lift and Drag of a Hydrofoil With Cavitation

Abstract

The occurrence of cavitation on hydrofoils can cause undesirable effects such as a decrease in lift, and an increase in drag. The goal of this research is to investigate the effect of water injection on the lift and drag coefficient of a hydrofoil. An unsteady uniform flow of water over a 3-D NACA hydrofoil is numerically simulated. For the numerical simulation of a cavitating flow, a bubble dynamics cavitation model is used to describe the generation and evaporation of the vapor phase. The RNG k-ε turbulence model is used as a turbulence model. A modification to the turbulent viscosity, which is necessary to simulate the cloud cavitation, is implemented. This simulation is implemented for various angles of attack and different injection velocities. Comparison between experimental data and the numerical simulation obtained here is done to validate the numerical results. The results presented show that, as the mass flow of the water injection increases, the lift coefficient decreases for all angles of attack but the rate of this decrease decreases for higher angles of attack. As the mass flow rate increases, the drag coefficient increases more for small angles of attack, and decreases for larger angles of attack, and the injection does not change the drag coefficient as much for large angles of attack. In general, water injection does not increase the lift and does not decrease the drag for all angles of attack.