Abstract
The general problem of erosion of turbine blading under wet steam operating conditions is reviewed and remedial methods available to the design engineer are considered. Of these, direct attack on the source of erosion, steam-borne water drops, is most attractive and is examined in some detail.
Five stages may be distinguished in the process culminating in erosion. They are: formation of droplets, their deposition on diaphragm blading, subsequent detachment, acceleration towards the moving blades and final impact with them.
The possibilities of interrupting this process at any stage are discussed and the paper primarily deals with the experimental investigation of these possibilities for the three intermediate stages using a full sized cascade of hollow last stage diaphragm blades. This enabled various configurations of extraction slots to be investigated as well as the effects of energizing the blade wakes and heating the blades. The construction and operation of the cascade and associated instrumentation are discussed and results are presented in terms of blading efficiencies for the various processes.
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