Structure of secondary liquid phase downstream of moving blades in LP cylinder stages of steam turbine

Measurements have been made of secondary liquid phase downstream of moving blades of the penultimate and the last stages of a 200 MW turbine. Three types of mechanical probe were employed to obtain data about structures, direction of motion and flow rate of secondary liquid phase. The measurements have revealed a difference in the direction of motion of the vapour phase and the secondary liquid phase, and non-uniformity in both the separation of water films from trailing edges and the specific flow rate of the secondary liquid phase with radius. Data has been obtained about the number of droplets, their mass, and the variation of mean diameters of droplets along the blades with working conditions. A correlation has been obtained between the critical Weber number and the Reynolds number defined by the initial width of the wake downstream of the trailing edge. Good agreement between turbine measurements taken and those made in wind tunnel cascades has been established, and a universal relationship has been obtained, which should be valid for both moving and fixed blades. Furthermore, the probable mass distribution of secondary droplets downstream of the moving blades has been established. (author)