Simulation Of Cryogenic Cavitation By Using Both Inertial And Heat Transfer Control Bubble Growth

The study is concerning the modeling of cavitation in cryogenic flows. The energy equation for the mixture is solved in conjunction with the mass and momentum conservation, and the evaporative cooling effects of cavitation are accounted for. Usually the cavitating flows are modeling with the basic hypothesis of isothermal flow, however it’s known that there is a temperature decrease in the vapor cavity in the case of cryogenic fluids. These fluids, in fact, are characterized by larger compressibility if compared with fluids, such as water, at room temperature, by a small difference in density between vapor and liquid phases and by a small latent heat of vaporization. The aim of this paper is a numerical investigation of this phenomenon, using a multiphase formulation that accounts for the energy balance, variable thermodynamic properties of the fluid and nucleation transport equation. In cavitating flow it has been assumed that there are plenty of nuclei for the inception of cavitation. Thus, the primary focus is on proper accounting of bubble growth and collapse. The expansion/contraction rate of the vapor bubble, is dominated by two mechanisms: a momentum that is needed to push away/pull up ambient liquid, and a heat transfer that is needed to drive phase change at the interface between the bubble and ambient liquid. They are called the inertia (momentum) control and the heat transfer control, respectively. In the expansion process the bubble radial movement is dominated by the inertia only at first and then changes to the heat transfer control. Over the whole contraction process it is controlled by the inertia. In the present work a cavitation model has been implemented by the user in the code Fluent 12.0, according this bubble behavior. Numerical results have also compared with the results obtained by the Schneer-Sauer cavitation model.