Development of CFD code 'MATIS-SC' for steam with nonequilibrium condensation

A steam control valve, steam turbine and other plant structures in the steam piping like orifice may cause vibration, noise and erosion. For the rationalization of maintenance and management in the plant, it is important to clarify the flow characteristics in detail and the prevention method. We have researched the flow instability of the steam control valve by both the experiment and the CFD (Computational Fluid Dynamics) calculation, and clarified the mechanism of the pressure fluctuation in the middle opening condition and suggest the way to prevent the pressure fluctuation. But, as we have used the air as a working fluid in our previous research instead of the steam that is used in the power plant, we can't consider an effect of a condensation, especially a rapid condensation from a supersaturated steam condition, called 'nonequilibrium condensation'. Nonequilibrium condensation causes a discontinuous property change, and this may cause the large amplitude of the fluctuation. Therefore, in this report, we developed CFD code 'MATIS-SC', which can calculate the steam flow with nonequilibrium condensation by a hybrid model that is combined with a steamtable model and a classical nucleation theory model. And we confirmed a validity of MATIS-SC by a benchmark test. (author)