11th European Conference on Turbomachinery Fluid dynamics & Thermodynamics
Erosion is one of the major problems that restricts the lifetime of hydraulic turbines, especially the parts exposed to higher flow velocities. This paper presents a numerical simulation of erosion by solid particles entrained by the water flow through the components of a small Francis turbine. The computation of particle trajectories used our developed Lagrangian tracking code that considers random particle size and shape distribution and the effects of turbulence and near wall as well as the stator/rotor relative positions. As the impacts were predicted, a semi empirical erosion model was used to assess the mass erosion and the geometry degradation. The nature of the flow field in the runner of the investigated Francis turbine leads to a fluid-particle interaction more complex and strongly affecting the erosion patterns. The obtained results allow identifying the critical areas of erosion wear, where surfaces coatings are necessary to increase the lifetime for these sand laden water turbines.