关键词: 湿蒸汽, 跨声速, 两相流, 凝结, 热力学, 激波

Abstract:

Wet steam condensation flows presents a high degree of non-equilibrium characteristics. At present, the condensation parameters are obtained by using semi-empirical formula, while heat transfer temperature difference and coupling problems are seldom considered. A simple condensation nucleation model and droplet growth model for non-equilibrium phase change of wet steam is established in this study. In order to calculate the wet steam parameters and condensation shock wave distribution of non-equilibrium condensation flows, the second-order TVD scheme is adopted. The influence of thermodynamic properties of inlet wet steam on the non-equilibrium condensation flow is examined, the influence of inlet pressure on the condensation characteristic is discussed, and various patterns of inlet subcooled temperature on nucleation rate, droplet number, condensation shock are summarized. It is found that as inlet pressure increases, the condensing location moves upstream. At a lower import subcooled temperature, the condensing position moves downstream. At higher Mach number, nucleation occurs. As the import subcooled temperature increase, the wetness of non-equilibrium condensation phase transition will be higher. After the onset of condensation shock, steam expands continuously along the nozzle and the flow pattern is similar to isentropic flow.

Key words: wet steam, transonic, two-phase flow, condensation, thermodynamics, shock wave