ANALYSIS OF EROSION IN HYDRO TURBINES

Abstract

As it is well known that hydro turbine in a hydro power plant constitutes of one of the most important component and if it is not functioning properly or out of order and maintenance is required than the plant suffers a huge loss in its capacity of power generation which is itself a source of revenue for it and thereby suffering correspondingly huge economic losses. Moreover even one percent loss in efficiency of the turbine due to cavitation / silt erosion is responsible for huge economic losses and revenue to a utility . For many years, solutions to the problem have been sought with only partial success. Despite advances in hydraulic-laboratory instrumentation and use of large-capacity computers to model three-dimensional flow through a runner, cavitation erosion remains a prime concern to owners of hydropower plants. In this dissertation cavitation erosion has been dealt in detail. Number of research to establish the empirical relationship to study the effect of cavitation have been developed . Relationship between cavitation intensity and specific speed or power plant turbine sigma (up,Thomma's cavitation factor) were combined for cavitation analysis in hydro turbine .Under the present study a different approach has been taken, using an empirical equation developed by J.L.GORDAN that establishes the setting of a hydraulic turbine with respect to tail water and all these equation have been applied to an actual site Chilla in Rishikesh . Based on IEC cavitation guarantee range different submergence levels , mass loss , efficiency loss and loss in power generation is estimated for the site . Based on the study the loss of power generation due to cavitation erosion and optimum submergence level to minimize cavitation erosion losses have been suggested . The study may also be useful for improving the accuracy of the empirical relations developed earlier.