Application of multiple interacting bubbles for particle fragmentation at cryogenic temperature

Two-phase flow in cryogenic system¹ is very common due to unavoidable heat inleak and low boiling points of cryogenic fluids. Although it may be detrimental to transfer lines, fluid handling equipment, etc., the flow conditions can be utilized for controlled erosion and particle fragmentation instead. In this study, the erosive effects possible during vapor formation are identified for a circular material target placed in the vicinity of bubble-array in a cryogenic environment (gaseous nitrogen or GN2 bubbles in liquid nitrogen or LN2). The physical effects observed during the interaction include shockwaves due to fast bubble-expansion, liquid jet-hammering, and lateral shear of the surface. The flow-field analysis is conducted to evaluate the typical magnitudes of these phenomena. Results indicate fluid-hammer pressure of 33 MPa as well as jet impact velocity of 48 m/s, which may be sufficient to dent BCC metals at LN2 temperatures. Further, the values obtained for air bubbles in water are also compared. This study can help to understand better the erosive effects of multiple bubbles for prospective applications.