Abstract: Spontaneous condensation flows are highly non-equilibrium processes, which has strong coupling with the gas flow field in the two-phase condensing flow. The development of accurate multi-phase numerical model is necessary to reveal the mechanism of the non-equilibrium condensation flow. The gas-liquid inter-phase slip not only has great influence on the gas flow and the motion trajectory of condensing droplet, but also would affect the condensation process. A multi-fluid condensing model is presented for the multi-component condensing system, of which the gas-liquid inter-phase velocity slip and the temperature difference is taken into account. The model is used for the numerical analysis of the wet steam condensing flow in supersonic nozzle. The simulation results showed that, the inter-phase velocity slip has significant effects in the two-phase wet steam flow, and the proposed multi-fluid model which takes the inter-phase slip into account can improve the simulation accuracy. In the wet steam flow, the inter-phase slip and temperature difference are very significant at the initial stages of condensation, and then the non-equilibrium properties almost disappear until the near equilibrium state is reached.

Key words: condensation, inter-phase slip, multi-fluid model