Detailed Analysis of Flow in Two Pelton Turbines with Efficiency and Cavitation Prediction

This paper presents results of the numerical analysis of two Pelton turbines: a 6-jet turbine for middle head and a 2- jet turbine for high head. For the 6-jet turbine losses in manifold, quality of the jets and turbine efficiency were predicted and validated with the experimental data. Additional improvement of accuracy of efficiency prediction was obtained with cavitation modelling. It was also checked that there was no interaction between the evacuating water sheets and the incoming jets. For a 2-jet turbine cavitation prediction was done. Small vapour cavity at the inner side and a larger one at the back side of the bucket were observed. Detailed analysis of cavitation and condensation processes showed that the conditions for cavitation pitting were not fulfilled.