Liquid and Gas-Phase Distributions in a Jet With Phase Change

A two-phase flow high-velocity jet with phase change was studied numerically. The jet is assumed to be created by the two-phase critical flow discharge through a pipe of variable length and attached to a vessel containing the saturated liquid at different stagnation pressures. The jet flow is assumed to be axisymmetric and the modeling of the two-phase flow was accomplished by a nonequilibrium model that accounts for the relative velocity and temperature difference between the phases. The numerical solution of the governing set of balance and conservation equations revealed steep gradients of flow properties in both radial and axial directions. The liquid phase in the jet is shown to remain close to the jet axis, and its velocity increases until it reaches a maximum corresponding to the gas velocity, and thereafter decreases at the same rate as the gas velocity. The effect of decreasing the pipe length is shown to produce a larger disequilibrium in the jet and a double pressure peak in the total pressure distribution. A comparison of the predicted total pressure distribution in the jet with the experimental data of steam–water at different axial locations is demonstrated to be very reasonable.