Numerical analysis on dynamic evolution characteristics of cryogenic cavitation through a Venturi tube

Abstract

Venturi tube can be used to measure the flow rate of stable single-phase fluid, which plays an important role in chemical industry, energy, aerospace and other fields. Due to the complex physical properties of cryogenic fluids, it is of great significance to study the cavitation characteristics of cryogenic fluids for practical engineering. In this paper, the modified Zwart cavitation model is used to study the evolution characteristics of cryogenic cavitation in Venturi tube and its relationship with turbulent kinetic energy under different pressure ratios by using dimensionless number P_r instead of cavitation number. The P_r value affects the development of cavitation to a large extent. When P_r = 1.3, cavitation is in a stable development mode. When P_r = 2.3, the development mode of cavitation changes from steady state to dynamic state. The temporal and spatial correlation between cavitation and vortex structure is studied by Q-criterion, and the geometric similarity between cavitation cloud and vortex structure in the development process is analyzed. The entropy production caused by velocity gradient change, turbulent dissipation and wall shear stress is further analyzed by entropy diagnosis method. The results show that the change of P_r value plays a leading role in the distribution of entropy production, and the generation and collapse of cavitation in the evolution process also have a great influence on the distribution of entropy production.