Direct numerical simulation of bubble cavitation at a wall in micro-gravity

Cryogenic tanks used in space applications face challenges due to propellant management, among which is phase change induced by a depressurization. Pool cavitation at the wall in pure methane under micro-gravity conditions is investigated, analyzing its impact on vapor creation and wall heat transfer. A compressible two-phase flow solver, including phase change and conjugate heat transfer, is used. After a validation with available experimental data for single bubble cavitation at the wall in micro-gravity, numerical simulations varying the depressurization amplitude and rate are carried out. Three distinct growth phases are put into evidence: an expansion-controlled phase, occurring within the depressurization time frame, and a transition phase leading to a diffusion-controlled growth where the bubble behaves as in a superheated liquid at constant pressure. Results allow to show the impact that compressible effects have on the phenomenon, and to demonstrate the importance of accounting for a nano-region at the contact line, strongly affecting the wall heat transfer. • A compressible solver with phase change is used to study wall bubble cavitation • The solver is validated with a comparison against experimental data • Results show that the nano-region influences the bubble growth and wall heat transfer • Relative contributions of expansion, variable density and phase change are estimated • The impact of the depressurization amplitude and rate are investigated