A Numerical Study on the Effects of Cavitation Number on Cavitating Mixing Layer of Liquefied Natural Gas (LNG) behind a Flat Plate Splitter

摘要

The mutual interaction of shear layer instabilities and phase change in a two-dimensional, unsteady cryogenic cavitating mixing layer is investigated using numerical simulation. The model is developed based on homogeneous equilibrium mixture (HEM) approach in a density-based framework to compute the temperature-dependent cavitation field for liquefied natural gas (LNG). The mixing layer is simulated for vorticity-thickness Reynolds numbers of 44 to 215 and cavitation numbers of 0.1 to 1.1. At the lowest cavitation numbers, steady vapor cavities are initiated on the splitter plate, followed by roll-up of the separated shear layer via the well-known Kelvin-Helmholtz mode. Unsteady, shear-driven cavitation then occurs as vapor cavities nucleate and grow from the low-pressure cores in the rolled-up vortices. As the Reynolds number and cavitation number are varied, thermal effects and baroclinic vorticity production are found to have significant impacts on the mutual interaction of shear-layer instabilities and unsteady cavitation processes.