Paper 39: The Flow of Wet Steam in a Turbine

Abstract

This article considers methods of calculating condensation processes in wet steam turbines. Equations are given for determining the rate of nucleation, the growth of droplets, and the wet steam parameters. The condensation processes within the blade ring of a steam turbine are used by way of example. It is made clear that the condensation process is continuous at large enthalpy gradients. Under these conditions the theory of discontinuous condensation will not represent the actual process. Calculations based on the kinetic theory of phase change agree well with experimental findings. The constructional features of the blading which operates within the Wilson zone can have a considerable effect on the extent of the undercooling and on the size of the droplets. The trajectories of the droplets in the space between blade rings can be determined using standard approximate equations. The Coriolis force has a considerable influence on the motion of the entrained liquid within the moving blades. Under the influence of this force the liquid may move either with the flow or against it.