Multidimensional Vibro-Acoustical Diagnostics of Cavitation: Theory and Illustration on a Kaplan Turbine

Abstract

Korto’s multidimensional method for vibro-acoustical diagnostics and monitoring of turbine cavitation is based on a high number of spatially distributed sensors and the signal and data processing that systematically utilises three data dimensions: spatial, temporal, and operational. The method delivers unbiased data on cavitation intensity and rich diagnostical data on cavitation mechanisms. It is applicable on Kaplan, Francis, bulb, and reversible pump turbines, as well as pumps. In this paper, the theory of the method is introduced, and its application is illustrated on a prototype and three models of a Kaplan turbine. In the considered case, two distinct cavitation mechanisms responsible for the two erosion patches found in an overhaul are vibro-acoustically identified, quantified, and analysed. The cavitation quality of the models is compared. Cavitation as a source of vibration is discussed.