Numerical simulation of dynamic stall around an airfoil in Darrieus motion

The objective of this study is to investigate the two-dimensional unsteady flow around art airfoil undergoing a Darrieus motion in dynamic stall condi tions. Fbr this purpose, a numerical solver based on the solution of the Re ynolds-averaged Navier-Stokes equations expressed in a streamfunction-vorti city formulation in a non-inertial frame of reference was developed. The go verning equations are solved by the streamline upwind Petov-Galerkin finite element method (FEM). Temporal discretization is achieved by second-order- accurate finite differences. The resulting global matrix system is lineariz ed by the Newton method and solved by the generalized minimum residual meth od (GMRES) with an incomplete triangular factorization preconditioning (ILU ). Turbulence effects are introduced in the solver by an eddy viscosity mod el. Our investigation centers on an evaluation of the algebraic Cebeci-Smit h model (CSM) and the nonequilibrium Johnson-King model (JKM). In an effort to predict dynamic stall features on rotating airfoils, first we present s ome testing results concerning the performance of both turbulence models fo r the flat plate case; Then, computed flow structure together with aerodyna mic coefficients for a NACA 0015 airfoil in Darrieus motion under dynamic s tall conditions are presented.