Numerical study of cloud cavitation effects on hydrophobic hydrofoils

Abstract

To explore the effect of hydrophobicity on cloud cavitation, the behaviors of cloud cavitation over the Clark-Y hydrofoil under various slip condition were investigated. Large eddy simulation (LES) was used for the turbulence model. The mass transfer model, which was considered to be a two-phase mixture flow, was used for the vaporization and condensation processes in the transport equation. The volume of fluid (VOF) scheme was used to track the interface of the dispersed phase by using the local volume fraction. Slip strength was controlled using the friction coefficient. The cavitation model in this study agreed with experimental and previous numerical studies. The results show that as the slip strength grew stronger, the friction drag was reduced; the cavity became longer and the shedding frequency decreased. For this reason, cloud cavitation is stabilized in condition of strong slip strength. Thus, a relatively weak re-entrant jet occurs in conditions of strong slip strength which gives rise to small amount of vapor shedding at the closure. This means that cloud cavitation instability was alleviated as the hydrophobicity increased.