Design and numerical study on Pelton turbine in reverse osmosis desalination system

Pelton turbines have emerged as effective energy recovery devices in reverse osmosis desalination systems, particularly under high-head, low-flow operating conditions. This study presents the design, numerical modeling, and experimental validation of a 50-bucket industrial Pelton turbine for such applications. A multiphase flow simulation based on the Volume of Fluid method was conducted to capture transient jet–bucket interactions and internal water film evolution. Three dominant flow patterns were identified at the bucket front: initial jet entry, jet perpendicular to the bucket, and jet moving along the bucket bottom to the outlet. Each of these stages corresponds to distinct energy conversion processes. Both numerical and experimental results indicate that the turbine achieves an efficiency exceeding 70 %. The analysis revealed that higher heads enhanced torque coefficients and accelerated the transition to high-efficiency states, but also led to localized pressure peaks near the splitter and bucket base, increasing energy losses and dynamic fluctuations. The study also revealed that the jet's incident angle plays a key role in energy conversion: perpendicular jet entry minimized inlet losses and improved outlet energy recovery. These findings provide a theoretical basis for optimizing bucket design to enhance the performance of Pelton turbines in reverse osmosis desalination units.