Transient CFD Analysis of a Pelton Turbine

Hydropower is no doubt a major source of green power generation. Pelton turbines are widely used in hydropower generation because they are the most efficient type of water turbine available today. Franco Tosi - a leader in the production of hydraulic and power steam turbines whose products are installed in 40 countries around the world - engaged EnginSoft's services to assist in the performance evaluation that needed to be done to upgrade an existing hydropower plant. The study was specific to a Pelton turbine that needed to be upgraded. EnginSoft developed a Computational Fluid Dynamic (CFD) analysis methodology for the project. This was an essential step in acquiring sufficient data to assist in the design that was ultimately used to upgrade the turbine in this power plant. The analysis methodology was applied to an existing machine in order to compute the actual turbine efficiency.

The Physics behind the CFD Analysis of a Pelton Turbine

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 on the Pelton Turbine

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.

How can EnginSoft help your Green Power Projects get to market faster?

The Pelton Turbine analysis is just one of the many green power projects that EnginSoft has assisted with. CFD is now considered an essential tool in the design of Pelton turbines because it allows engineers to evaluate the three dimensional fluid flow on the bucket and most importantly it allows the application of "what if" scenarios allowing engineers to quickly estimate the effects of modifications on the machine design.

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Raves

"EnginSoft gave us an impressive insight into the fluid dynamics of such a complex machine. They helped us develop a CFD analysis procedure to use for performance evaluation in addition to providing us with the results of a specific design."

Emanuel Pesatori
Franco Tosi Meccanica S.p.A.

 

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