Aerodynamic Forces on a Steady Airfoil in a Two-Stream Shear Layer*

Most problems in aerodynamics traditionally consider a uniform approach velocity, but in numerous circumstances of the complex flows found in nature the approach flow can be significantly non-uniform. As part of a larger investigation into airfoil aerodynamics in the presence of non-uniform approach flow, this study considers the aerodynamic loads on a steady NACA-0012 airfoil at chord Reynolds number of 1.2×10⁴, when placed inside a two-stream shear layer. Load measurements are carried out over a wide range of angles of attack with the airfoil placed at three downstream locations where the mean and fluctuating streamwise velocity profiles in the shear layer exhibit self-similar behavior typical of two-stream shear layers. The three measurement locations considered allow us to assess the influence of mean shear rate and shear zone thickness on the aerodynamic loads. The measured mean lift and drag forces are compared against our previous results in uniform freestream and a non-uniform approach flow with steady shear profile.