Numerical analysis of factors influencing thermal effects generated by cavitation flow of cryogenic fluids

Abstract

Thermal effects dramatically impact on the cavitation dynamics of cryogenic fluids. Thus, to study the thermal effect factors influencing cryogenic cavitation, numerical simulations were conducted considering an axisymmetric ogive and a 2D quarter caliber hydrofoil in liquid nitrogen and hydrogen, respectively. The modified Merkle cavitation model and filter-based turbulence model were applied to account for the thermodynamic properties of the fluid. The energy equation was modified considering the cavitation phase change effects. Compared to the experimental data, the numerical method satisfactorily predicts the cryogenic cavitation flows. Based on the numerical results, the thermal effect characteristics in the cavitation flow of cryogenic fluids were investigated. The thermal effects in cryogenic cavitation is obvious when vapor content in constant location is considerably low, where the cavity becomes more porous and the interface becomes less distinct. The factors influencing the thermal effects in cavitation such as the temperature, fluid type and velocity were analyzed. Findings showed that thermal effects of cavitation were prominent around the critical temperature of cryogenic liquids. Compared to the thermal effects in liquid nitrogen, those in liquid hydrogen were more distinct because of the changes in the density ratio, vapor pressure and other fluid properties. When the flow velocity is higher, the thermal effects of cavitation are suppressed as the pressure depression caused by evaporation is much smaller than the dynamic pressure.