Navier-Stocks Computations of Wind-Turbine Airfoil using Low Mach Number Preconditioning

Wind turbine airfoil is numerical simulated by using the governing equations of compressible fluids in this paper. The Reynolds averaged Navier-Stokes computations are combined with low Mach preconditioning and implicit matrix-free lower-upper symmetric Gauss-Seidel (LUSGS) iteration on unstructured meshes, and the results are improved at the very low velocity speeds which are representative of the flow field around a wind turbine airfoil. Detailed LUSGS algorithm with preconditioning is present in this paper, which is improved to cost less data storage and computational time for steady flow. The steady and unsteady characteristics of static 2D-S809 airfoil are analyzed by the numerical results and compared between calculations and tests. Aerodynamic coefficients have been got using the algorithm of this work at all angles of attack. The unsteadiness induced separation bubble shedding has been captured by this method finally.