Paper 19: Conditions Producing Concentrated Erosion in Large Steam Turbines

Abstract

The paper presents the results of intrascope observations and instrument traverses in the final stages of three large steam turbines and describes the processes controlling the distribution of erosion on the moving blades. Concentrations of eroding water are shown to be produced by complex steam flows in the final stage which redistribute the water depositing on the surfaces of fixed blades. Of the three turbines considered, each has a different redistribution process, two leading to concentrated erosion, the third to a more uniform distribution of damage. In the former two turbines, it was found that the concentrations of water could be dispersed by small fences fitted to the fixed blade trailing edge, this simple modification promising to extend significantly the operating life of the moving blades.