Modeling critical flashing flows issuing from long pipe

A study is presented of the issues encountered in the modeling of the phenomena that occur in flashing liquid jets. A physically reasonable method is proposed to predict non-equilibrium two-phase critical flow, followed by an axisymmetric supersonic expansion. Based on the evaporation wave model, Rankine-Hugoniot analysis is performed to obtain the Chapman-Jouguet solution for the flow quantities behind the evaporation wave. Results are presented for the critical mass,flow rate, the wave angle, the intact liquid core length as well as the vaporization index, the void fraction, the turning angle, and the normalized velocity behind the evaporation wave. Available literature data are compared with the predictions. Based on the method of characteristics, a typical flow field downstream of the evaporation wave is computed with the assumption that the mass transfer between phases is negligible in this region. By reference to the computed streamlines, a source flow model is proposed to demonstrate the cylindrical symmetry of the flow.