A density-based solver using real gas properties for R744 supersonic flashing simulations.

A density-based solver based on the OpenFoam library is coupled with a tabulated equation of state which allows to accurately compute the properties of CO2 at a reduced computational cost. The homogeneous equilibrium model (HEM) is considered to predict the phase-change phenomenon. The Navier-Stokes characteristic boundary condition is used as the outlet boundary condition to guarantee the accuracy and stability of the simulation. As a result, this solver is suitable to simulate supersonic flashing CO2 flows in converging-diverging nozzles and supersonic ejectors. Firstly, the flows in the converging-diverging nozzle are simulated under supercritical condition. A good agreement in terms of pressure distribution is obtained. Then, a two-phase CO2 ejector is investigated numerically. Once again, a good agreement is obtained against experimental wall pressure measurements.