Development and validation of a homogeneous flow model for simulating cavitation in cryogenic fluids

Fluid machinery used for pumping cryogenic liquid fuels are severely impacted by the onset and development of cavitation. Cavitation in non-cryogenic fluids is commonly assumed to be isothermal, but cavitation in cryogenic fluids is substantially influenced by thermal effects. In the present paper, we present a computational fluid dynamics solver for cryogenic cavitation based on modifications to an isothermal cavitating flow solver presently available in the open-source OpenFOAM® software library. The homogeneous flow model is employed to compute the multiphase solution in an Eulerian framework. Thermal effects are captured via a coupled solution of a cryogenic form of the density, momentum, and energy equations. Thermophysical properties of the cryogenic fluid are corrected using the computed pressure and temperature fields to account for the baroclinic nature of the density field and temperature dependence of the fluid's saturation properties, specific heat, and dynamic viscosity. The resulting cryogenic solver is validated against experimental measurements of cavitating flow of liquid nitrogen in a circular orifice and a Laval nozzle, achieving good agreement for a range of operating conditions. Cavitating flow of liquefied natural gas (LNG) in the Laval nozzle is simulated to investigate the influence of thermal effects on the vapor vaporization and condensation processes. The results show that thermal effects slow the condensation of cavitating LNG such that the overall vapor production is enhanced compared to a baseline isothermal case. This behavior is jointly attributed to thermally-modulated variations in the saturation pressure near liquid/vapor interfaces and enhanced production of vorticity owing to the presence of baroclinic production mechanisms in the cryogenic solver.