Numerical study of the entropy production characteristics in cryogenic liquid nitrogen cavitating flow

Abstract

This study applies the entropy production theory to the cryogenic liquid Nitrogen cavitation flow to explore the inducement mechanism of the entropy production and to reveal the cavitation effect on it. This research uses the modified cavitation model which considered the thermodynamic effect of the liquid nitrogen cavitation flow and uses the k-ω SST turbulence model to solve the viscosity coefficient of the flow field. The detailed entropy production characteristics are analyzed based on the entropy production theory. The results show that the entropy in the cryogenic cavitation flow is mainly caused by the direct dissipation term (EPDD) and wall shear stress term (EPWS), while the EPMT and EPFT can be ignored. The velocity gradient and the process of cavitation are the crucial causes of the entropy generation. Regions with higher velocity gradients will be accompanied by higher entropy production rates compared with other regions, resulting in the irreversible energy loss. The irregular flow of fluid causes energy to be lost in the form of heat, while the occurrence of cavitation will produce mass and momentum exchange at the cavity boundary, which causes energy loss.