Experimental Investigations on Cavitation in Large Kaplan Turbines

Experimental investigations on cavitation in Kaplan turbines are to achieve: (1) Characteristics of sound waves emitted by cavitation, (2) The laws of cavitation intensity varying with operating states donated by water head and power output, (3) The relationship of cavitation intensity to cavitation erosion level, In this sense, a series of tests have been proposed and carried out in laboratory and in field: (1) Cavitation tests on model turbine: the sound waves of cavitation can be detected with different cavitation coefficients in some typical operating states. And cavitation is pictured with stroboscope and camera. Cavitation intensity along with cavitation coefficients has been discussed. The characteristics of sound due to cavitation are distinguished. (2) Load change tests and water head change tests on prototype: the latter are realized via on-line cavitation monitoring method, The cavitation intensity on different water head and load has been traced out. (3) Comparison tests on prototype turbines before and after runner blades repairs. The cavitation erosion level is estimated according to the cavitation intensity at a fixed operating state such as rated power and designed water head. The achievements have been successfully integrated into the on-line cavitation monitoring and analysis systems installed on 3F, 10F, 14F, 19F and 21F turbines in Gezhouba Hydro Power Plant.