Numerical Investigation of Cavitating Flow Around a Hydrofoil Considering Advection–Diffusion and Precipitation of Dissolved Gas in Liquid

Hydraulic cavitation is mainly affected by the pressure or velocity field, but the detailed flow structure also depends on other factors such as surface wall roughness or working fluid quality. Among those, the present study has focused on the influence of air content as a non-condensable gas in water, which is one of the factors in water quality. The novel point in this study is that we have applied a simple but physics-based model taking account of the mass transfer of the non-condensable gas based on mass conservation law in the CFD simulations. On the basis of the assumption of a homogeneous bubbly flow, the simulations were conducted by solving five governing equations for cavitation around a hydrofoil of Clark Y-11.7% (angle of attack is 8°) modifying interPhaseChageFoam of OpenFOAM v1706. As a result, the lift coefficient containing air showed higher values than the case without the gas in a certain developed cavitation state showing a periodic change of the hydrofoil lift force, and it may improve the current prediction accuracy of the lift in many CFD simulations. In the case with much air content, an attached cavity around the leading edge due to the influence of the precipitation of air was confirmed even at the time of the minimum lift force, different from the case with little content of air.