Effect of curved rigid surface on the collapsing cavitating bubble in cryogenic environment

Abstract

The high impact erosive pressure resulting from collapsing cavitating bubble has advantages in stone fragmentation and shock wave lithotripsy. They carry damage potential also and can erode the curved hydrofoil of any turbo-machinery, and, still somewhat obscure in cryogenic liquids. Once the material loses its surface smoothness, the flow-field surrounding the collapsing bubbles is affected by the newly formed irregular surface geometry. In this way, the bubble collapse is significantly influenced by the curvature of the rigid boundary. In this work, a collapsing cavitating bubble near a curved rigid surface dipped in cryogenic fluid has been investigated numerically to illustrate the effect of different surface configurations (i.e. Convex i.e. ξ < 1 and Flat ξ = 1 surface) using volume-of-fluid (VOF) method in a compressible framework for different standoff distance (γs ). TAIT equation for the surrounding liquid is used to model shock perturbations during the collapse, whereas ideal gas equation is used for the modeling of compressibility of vapor (or gas) bubble. Here, different dynamical features such as jet formation, bubble-shape evolution (necking and splitting) and vortex ring motion (free and wall vortex) is shown for collapsing cavitating bubble in cryogenic environment and compared with the room-temperature fluid combination i.e. water-air for flat and convex wall configurations for different stand-off distance.