Aerodynamic study of a circular arc airfoil at low Reynolds numbers using Cartesian mesh CFD

The purpose of the study is to investigate the Reynolds number dependency of a circular arc airfoil at Reynolds numbers from 1x10(3) to 10x10(3) by CFD. A block-structured Cartesian-mesh CFD was employed to precisely predict the vortex flowfields in the low Reynolds number region. The calculated aerodynamic coefficients were reasonably matched with wind tunnel tests at different Reynolds numbers. The flow goes along upper surface at lower angles of attack, but separation on the upper surface occurs at the trailing edge as the angle of attack increases when the Reynolds number is 1x10(3). On the other hand, 2D vortices are formed on the upper surface at low angles of attack for Reynolds numbers of 5x10(3) and 10x10(3), and then the laminar separation bubbles (long bubbles) are formed as the angle of attacks increases. This causes the nonlinear increase of lift coefficient.