Non-equilibrium spontaneous condensation in transonic steam flow

Experimental and numerical investigations of non-equilibrium spontaneous condensation in transonic steam flow were carried out in low pressure steam turbine cascade to study the effect of exit pressure variation on two phase flow of saturated vapor and fine water droplet. The conditions at inlet to the test section were varied from a wet equilibrium to a superheated state by changing the cascade exit pressure.Experimentally it was found that the most important influence of rapid condensation on the pressure distribution is occurred on the suction surface, when the exit cascade flow is termed supersonic the heat release causes a pressure rise in the zone of rapid condensation, therefore the term condensation shock for this feature is misleading. In the numerical approach when the flow is regard subsonic the rapid condensation zone occurs downstream the throat and not accompanied by a pressure rise, while in the experimental test for the same case there is no sign of this condensation.

► The model of wet steam is very important in the analysis and design of steam turbines.
► Increasing information will decrease wetness losses in low pressure steam turbine.
► Increasing information will increase efficiency of wet stages steam turbine.
► Most important influence of rapid condensation is occurred on the suction surface.