Investigation of the Effects of the Jet Impingement Angle on Torque Generation at the Suction Surface of a Pelton Turbine Bucket

The performance of a Pelton turbine was investigated by means of an integrated numerical and experimental study that focused on the fluid dynamics associated with the bucket suction surface during the jet–bucket interactions. The transient pressure distributions and torque-generation mechanisms were characterized under a variety of conditions. The results revealed a distinct two-phase transition process: an initial high-pressure zone (θ = 48.7°) that generated a resistance torque was followed by a negative-pressure region (θ = 57.2°) that produced a significant torque enhancement. The impingement angle was quantitatively established as a primary control parameter since a direct correlation was observed between angle decreases and torque improvements. A thickness-based regulation method for the suction surface was developed to precisely control both the impingement angle and the subsequent jet trajectory. These results provide fundamental insights into the transient flow phenomena that affect the turbine efficiency and offer practical design guidelines for performance optimization in high-head hydropower applications. Critical knowledge gaps regarding the fluid mechanics of Pelton turbines were addressed using measurable benchmarks for bucket design improvements.