Numerical investigation of passive cavitation control using a slot on a three-dimensional hydrofoil

Purpose: The purpose of this paper is to study the mechanism and suppression of instabilities induced by cavitating flow around a three-dimensional hydrofoil with a particular focus on cavitation control with a slot. Design/methodology/approach: The transient cavitating flow around a Clark-Y hydrofoil was investigated using a transport-equation-based cavitation model and the stress-blended eddy simulation model was used to capture the flow turbulence. A homogeneous Rayleigh–Plesset cavitation model was used to model the transient cavitation process and the results were validated with test data. A slot was applied to the hydrofoil to suppress cavitation instabilities, and various slot widths and exit locations were applied to the blade and the cavitation behavior, as well as drag/lift forces, were simulated and compared to investigate the effects of slot geometries on cavitation suppression. Findings: The large eddy simulation based turbulence model was able to capture the interactions between the cavitation and turbulence. Moreover, the simulation revealed that the re-entrant jet was responsible for the periodic shedding of cavities. The results indicated that a slot was able to mitigate or even suppress cavitation-induced instabilities. A jet flow was generated at the slot exit and disturbed the re-entrant jet. If the slot geometry was properly designed, the jet could block the re-entrant jet and suppress the unsteady cavitation behavior. Originality/value: This study provides unique insights into the complicated transient cavitation flows around a three-dimensional hydrofoil and introduces an effective passive cavitation control technique useful to researchers and engineers in the areas of fluid dynamics and turbomachinery.