An Analytical Approach to Estimate the Effect of Surface Roughness on Particle Rebound

Atmospheric air is always contaminated by liquid or solid particles of different size, concentration and chemical composition. This leads to performance degradation during the operation of stationary or flying gas turbines. Erosion and the deposition of particles along the flow path are of particular importance. Multiple numerical studies investigated the influences of these phenomena. However, the basic challenge of modelling the particle wall interaction and its data spread with sufficient accuracy remains. In this work a model that estimates the statistical spread of rebound data due to target surface roughness through analytical considerations is presented. The model predicts the local impact angle of an individual particle by evaluating how deep a particle can theoretically penetrate the target surface with respect to its size. Based on roughness profiles which have been found to be characteristic for performance deterioration in compressor application a sensitivity study is conducted. A dimensionless roughness parameter Φ_R was found that characterizes the effect of target surface roughness on rebound spread data. The spread model is connected with a quasi-physical model, to evaluate the effect of surface roughness for a particle’s individual rebound behaviour. The synthesized data is discussed by taking into account measurement data reported in literature.