Analysis of the flow interference on a Pelton turbine at different operating heads

Abstract Flow interference is a phenomenon harmful for the Pelton turbines stable and high efficiency operation. In this paper, numerical simulation of unsteady multiphase flow on a Pelton turbine runner buckets and entire flow passage was carried out at three operating heads. Different types of flow interference were occurred for the turbine with larger nozzle opening: the water sheet interference on the same bucket surface from the adjacent jets, the bucket cutout-flow and jet flow interference, as well as the interference between bucket brim outflow and the following bucket rear surface. The highest turbine efficiency is about 88.0% appears at 1.00 H 0 , and efficiency decreases when deviating from the design head, especially at the low head decrease dramatically. The predicted unsteady flow patterns with bucket torque curves show that the self-designed Pelton turbine model with six nozzles opened at larger needle stroke is remains to be optimized. The relationship between the predicted flow interference and the decrease of runner torque and hydraulic performance is summarized.