Study of the cavitating instability on a grooved Venturi profile

Abstract

Instabilities of a partial cavity developed on a hydrofoil, a converging-diverging step, or in an interblade channel have already been investigated in many previous works. The aim of this study is to evaluate a passive control method of the sheet cavity. According to operating conditions, cavitation can be described by two different regimes: an unstable regime with a cloud cavitation shedding and a stable regime with only a pulsating sheet cavity. Avoiding cloud cavitation can limit structure damage since this regime is less aggressive. The surface condition of a converging-diverging step is here studied as a solution to control the cavitation regime. This study discusses the effect of longitudinal grooves on the developed sheet cavity. Analyzes conducted with laser Doppler velocimetry, visualizations, and pressure measurements show that the grooves geometry, and especially the groove depth act on the sheet cavity dynamics and can even suppress the cloud cavitation shedding.