Investigation of unsteady parameter effects on aerodynamic coefficients of pitching airfoil using coarse grid simulation

Abstract

In this article, the eects of unsteady parameters, including mean angle of attack, oscillation amplitude, reduced frequency, and pitching axis position, on the aerodynamic coecients of a pitching airfoil are studied. This investigation is implemented for high Reynolds number ows around a dynamic stall condition. The employed numerical method is a Coarse Grid CFD (CGCFD) method, in which the Euler equations are solved using a coarse grid with no slip boundary conditions, and a compressible surface vorticity connement technique. The required computational time for this method is signicantly lower compared to that of the full Navier-Stokes equations with a simple one-equation turbulence model. In addition, a multi zone adaptive spring grid network is applied to simulate the moving boundary, which further reduces the computational time. Using the described numerical setup separates the current work from the others. The obtained numerical predictions are in very good agreement with experimental data for the high Reynolds number ow. It is found that moving the pitching axis position to the right or left outside, and distancing it from the trailing edge or leading edge, has an inverse eect on aerodynamic characteristics. Furthermore, increasing reduced frequency results in a reduction in the lift hysteresis loop slope, and in the maximum lift and drag coecients.