Author(s): Wiebke Boden, Jorge Nunez, Guillaume Coudouel, Stephane Aubert, Jean-Christophe Marongiu, Alain Combescure, Richard Perkins
Linked Author(s): Wiebke Boden
Keywords: Smoothed Particle Hydrodynamics (SPH), Solid Particle Erosion (SPE), Fluid Structure Interaction (FSI), Pelton turbines
Abstract: A model for solid sediment transport in the framework of a Smoothed Particle Hydrodynamics (SPH) code in Arbitrary Lagrangian Eulerian (ALE) formulation has been developed to investigate the impact parameters of sediments on a surface. Particle trajectories were calculated by the Lagrangian integration of the particle equation of motion, wall effects and near-wall turbulence were taken into account. The simulations covered the particle size range from 10 ?m to 500 ?m. Next, the sediments� erosion potential was evaluated based on their impact parameters. The normal component of the sediment impact velocity was identified as the key parameter to estimate erosion on coated Pelton turbine buckets by comparing an oblique to a normal impact, where the normal velocity component was taken identical. These simulations were performed as a solid-solid impact without a fluid phase using a Finite Element (FE) code. Surface damage is supposed to be due to fatigue and evaluated firstly, by the range of stresses occurring in the material and secondly, by the number of impacts until damage. This number arises from a generally valid fatigue criterion for low and high cycle numbers. Subsequent fluid structure interaction (FSI) simulations with a coupling between the SPH and the FE code showed a slightly different deterioration pattern compared to the dry simulations due to the presence of the water jet. Erosion estimation was inferior to the results that were found by the uncoupled approach. Then, a comparison between 2D and 3D dry structure-structure simulations of the sediment impact allows error estimation of the damage evaluation made by the more efficient 2D simulations. Finally, based on all presented results, recommendations for future developments of the direct erosion simulations are made
Year: 2017