Thermodynamic modeling and simulation of cavitating nozzle flow

Numerical simulations of cavitating flows are frequently performed by applying simple law of state-cavitation models. Here, the phase transition criterion is usually defined by assuming that cavitation occurs, if the pressure drops below the equilibrium vapor pressure. Since this simple modeling should be improved, an advanced method is developed, which takes phase non-equilibrium effects into account. The inclusion of non-equilibrium effects is important for future simulations of high-speed flows in very small-scale injector nozzles. Related to the van der Waals theory, the new approach is based on postulating Gibbs free energy for the phase mixture. This leads to a rate equation for quality. The two-phase flow is treated numerically by combining the rate equation with a volume-of-fluid algorithm. Unsteady calculations of cavitating flow in a converging-diverging passage and in a channel with a triangular obstacle show cyclically developing cavitation zones. The capability of this model to predict typical effects of cavitation, e.g. the formation of a re-entrant jet, is studied. Simulation of cavitating flow in the channel with a triangular obstacle is compared with the experiment and with numerical investigations of other authors