Cavitation research results of hydroturbine impeller blades and their analysis

Abstract. Cavitation erosion affects the hydropower plants operation mode, destroys the surface of water-conducting way, affects the efficiency coefficient as well as the turbine output. The most common damage is observed on water-conducting ways having poor streamline shape, various ledges, irregularities along the water flow. Disruptive cavitations are formed initially on the rotation axes of vortexes, and the caverns of disruptive cavitation develop with the period subordinating the Strouhal Law. One of the methods of cavitational erosion field studies is the method of obtaining high-speed cavitational erosion of metal plates, which has low resistance to cavitation mechanical effects. It provides an opportunity to determine erosion degree and intensity at different modes of hydropower plants operation. The paper demonstrates the results of studying the cavitational erosion process of hydroturbine impeller blades of Zhiguli Hydroelectric Station (HS). Cavitation tests are conducted for three operating modes. Technological peculiarities are also described. The paper presents results of turbine blades of Unit 5 for three operation modes. The destruction areas of impeller blades peripheral edges are visualized. The study provides the results of field and laboratory cavitation tests of hydroturbine elements that serve as recommendations for repairing and restoration of damaged hydroelectric units of Zhiguli HS.