The physics underlying the problem is complex and requires a proper resolution of the interaction between the water jets and the bucket shaped rotor blades. In order to achieve this goal the numerical simulations had to account for:

• the multiphase nature of the problem due to the simultaneous presence of air and water (including water vapor if cavitation occurs)
• the motion of the runner blades
• the unsteady nature of the phenomena

The results of the CFD Analysis provided fundamental insights into the working conditions of the Pelton Turbine. More specifically:

• the ability to analyze the performance of various turbine functions such as the hydrodynamic torque and power output together with the magnitude of these quantities and their fluctuations
• a detailed resolution of the interaction flow behavior of the water jets with the wheel’s buckets
• the verification of the absence of mutual jet interaction
• detailed 3D studies of the water distribution on the bucket and of the fluid layer thickness
• the linkage of the fluid dynamic state of each single bucket with its actual contribution to the total shaft torque
• verification of the entity of the stator frame water recirculation phenomena in the wheel proximity
• the cavitation tendency of the machine was evaluated
• estimate of idle losses with free-to-air running wheel

Due to the advanced modeling requests and the need for transient analyses, numerical simulations were extremely computationally demanding. EnginSoft was responsible for implementing all of the procedures for parallel computing and provided high performance computing resources to Franco Tosi.