Numerical and experimental analysis of the hydraulic performance of a prototype Pelton turbine

Unlike the reaction turbines, the hydraulic performance of Pelton turbines varies due to the unsteady flow of the rotating buckets in time and space. This study experimentally and numerically investigates the dynamic performance of a Pelton turbine at five different operating conditions. The unsteady numerical simulations were performed with the SST turbulence model. The three-dimensional unsteady free surface sheet flow behavior in the rotating buckets was modeled by the two-phase homogeneous model. The model was used to analyze the dynamic flow patterns and the torque variations as the buckets rotated. The predicted hydraulic performance at different unit discharge rates are compared with the field test while the free surface flow patterns are compared with previous experimental and numerical results. The predicted relative efficiency agrees well with the field test results. The calculations were used to clarify the hydraulic mechanisms with unsteady free surface sheet flow in the rotating bucket.