Numerical assessment of erosion wear in Pelton turbine injectors

Abstract

The Pelton turbine is the main type of turbine used to develop hydropower resources in high-head sections and is more sensitive to sediment erosion. To analyse the causes of asymmetric erosion distribution on the injector surface, a solid-liquid-gas three-phase numerical study of Pelton turbine injectors is carried out. The results indicate that as the sediment diameter increases, the differences in particle discharge distribution among the jets of each branch also increase, and the asymmetric erosion distribution on the injector surface becomes stronger. The particle trajectory is influenced by the vortex structure, and fine particles mainly cause banded erosion, while coarse particles cause sheet erosion. At constant inflow conditions, the particle residence time is related to erosion morphology, and the particle velocity and the number of impacts affect the erosion rate on the injector surface. It is recommended to avoid long-term operation of the turbine under conditions of excessively small or large sediment diameters and to pay attention to the sediment erosion degree of the middle branch needle and the end branch nozzle of the water supply mechanism. The research findings of this paper can provide references for further optimization of the design, operation, and maintenance of the Pelton turbine.