Unsteady Aerodynamics Analysis for Low Reynolds Number and High Angles of Attack

The aerodynamic properties of asymmetric wake patterns behind an airfoil of 5% thickness at angles of attack <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\alpha\in[20^{o}-35^{o}]$</tex> with <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$5^{o}$</tex> increment in <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\alpha$</tex> are investigated. Two different Reynolds numbers based on the inflow velocity and chord length are 1000 and 2000. Aerodynamic coefficients are increased with the increasing angles of attack. Excess drag force is produced with the increase in the angle of attack. Hence, the aerodynamic performance is decreased with increasing angle of attack due to the decline in lift to drag ratio. The frequency analysis shows the transition at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\alpha=25^{o}$</tex> for Reynolds number 1000 causes a lower Strouhal number in comparison to the other angles of attack likewise <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\alpha=30^{o}$</tex> in case of Reynolds number 2000. Comparative instantaneous vorticity contours are presented to investigate the effect of the angle of attack for different Reynolds number.