基于OpenFOAM的超临界压力下低温射流大涡模拟

In order to get insights into the flow characteristics of cryogenic jet under supercritical pressure, the real⁃fluid model was implemented into open source CFD code OpenFOAM.The effect of real⁃fluid thermo⁃physical characteristics was introduced into the pressure correction algorithm, contributing to the development of the homogeneous solver for cryogenic flows under supercritical conditions.Transcritical and supercritical jets of LN₂ were studied using large eddy simulation, including the influence of ambient temperature and pressure.The results indicated that the real⁃fluid model developed can describe thermo⁃physical characteristics accurately within wide temperature and pressure range.The homogeneous solver can correctly reveal the flow structure of cryogenic jet under supercritical conditions, which was characterized by shear layer instability and turbulent mixing.These kinds of variable density jets showed self⁃similarity characteristics in turbulence fully developed region.Compared with transcritical jet, the supercritical jet showed higher turbulent mixing rate and shorter core length.Under higher ambient temperature or lower ambient pressure, the density gradient between cryogenic jet and ambient gas greatly reduced, which restrained the development of instability wave in shear layer, leading to the increase of jet core length and the decrease of jet spreading angle.