State of the art in numerical modelling of Pelton turbines

Pelton turbine (or Pelton wheel) is among the most efficient impulse turbines and has retained its existence in hydropower for well over a century. However unlike in the development of the reaction turbines, where Computational Fluid Dynamics (CFD) have been successfully applied for more than 20 years now, up until recently it was not feasible to perform CFD analysis of Pelton turbines due to the nature of the flow which is much more complex than in the reaction turbines. The recent developments in CFD models and tools together with the continuous increase in computational resource are bringing the CFD modelling up to a level suitable for industrial applications in development of Pelton turbines. Current published research in the field worldwide can be divided into two distinct branches of CFD models: the Eulerian specification of flow field, which tends to be more accurate, but also more computationally expensive, and the Lagrangian specification which is known to be less computationally demanding, however to date it cannot compete with Eulerian specification in terms of accuracy. This review paper is aiming at establishing the state of the art in numerical modelling of Pelton Turbines and would serve as guidance when choosing the optimum CFD modelling methodology and software available.