Modeling of spontaneous condensation in high-speed expansion of gaseous mixture

Many efforts have been undertaken to model the condensation phenomena in high-speed steam flow in a steam turbine. Spontaneous vapor condensation takes place not only in high-speed flows involving pure steam such as in a steam turbine but also in other gaseous flows such as the flow of hydro-carbon combustion products through a supersonic nozzle. In the present paper, the condensation models for pure steam flow have been modified and extended to include spontaneous vapor condensation in flows of gaseous mixture containing that vapor. The modified condensation models are implemented into the Eulerian/Eulerian approach within CFD++, the commercial CFD software suite from Metacomp Technologies. It is shown that condensation would occur in a supersonic nozzle when hydro-carbon combustion products expand through the nozzle such that the water–vapor pressure at the nozzle exit is well above the saturation pressure at the local temperature. Another numerical investigation on the condensation taking place in transonic moist air flowing over a NACA 0012 airfoil with an angle of attack illustrates that there is a stationary double shock system in the flow over the upper surface of the airfoil.