CFD simulation and analysis of performance degradation of wind turbine blades in dusty envirnonments

The surface of a wind turbine blade operating in a Saharan environment is subjected to dust accumulation which in turn induces surface roughness. The current work aims at providing a deep insight into the physical phenomenon of dust accumulation and its impact on the blade's aerodynamic characteristics. A computational fluid dynamics (CFD) model coupled with a deposition model is developed to assess the performance degradation of wind turbines operating in the dusty Saharan regions of the Middle East and North Africa (MENA). The full two-dimensional Navier-Stokes equations and the SST k-ω turbulence model were used to investigate the incompressible viscous flow past a two-dimensional airfoil section (NACA 63–215) of a wind turbine blade under clean and fouled surface conditions. The developed model is used to estimate the role roughness plays in promoting premature transition to turbulence and in fact flow separation has been identified by the numerical results. The effect of roughness height and roughness area on both the lift and drag coefficients have been inspected. For the purpose of validation, the model predictions are compared with the experimental data of Khalfallaha [1] and the numerical results of Nianxin Ren [3] and are found consistent with both.