Numerical simulation of wet steam condensing flow based on a two-fluid model

A two-fluid model of wet steam condensing flow was established, in which the effect of velocity slipping and coupling between the steam and liquid phases as well as the turbulent diffusion were taken into account. Referred to the transport equation theory of particle's turbulent kinetic energy, the SST k-omega-k(p) two-phase turbulence model was derived from the SST k-omega turbulence model considering the turbulent characteristics of the internal flow in steam turbine. In this model, the quasi-fluid concepts were introduced in order to analyze the turbulent transport properties of the particle phase, such as the viscosity, the thermal conductivity and the diffusion coefficient. Numerical simulation of wet steam flow with spontaneous condensation in a two-dimensional cascade indicates that the results predicted by the present model agree well with the experimental data, and show more reasonable flow details in many local regions. A three-dimensional numerical simulation of the wet steam flow in a turbine cascade indicates that substantive nucleation emerges firstly near the end wall where the wet steam flow reverts to equilibrium state earlier than that in the middle section. The outlet Mach numbers of the two phases along the blade height are different due to the presence of vortices. The model developed in this paper includes the effects of interactions between the two phases, and improves the precision of numerical simulation of wet steam flow with condensation.