Experimental investigation of propeller slipstream effects on the wing aerodynamics and boundary layer treatment at low Reynolds number

Abstract

In this research, an experimental investigation was conducted to predict the Laminar-turbulent transition over the wing surface. Furthermore, the effects of a tractor propeller slipstream on both wing aerodynamics and transition front were studied. For tests, a rectangular wing was used with a NACA 6-series airfoil section and with a total of 22 pressure orifices. Unsteady pressure measurements were performed over the upper and lower surfaces of the wing in different spanwise locations at different incidence angles. Existence of propeller slipstream changed pressure distribution over the wing surfaces, in both chordwise and spanwise directions and hence affected the wing loading distribution. Statistical analysis of pressure signals was used to predict the boundary layer transition over the wing by computing the root mean square and skewness of the pressure data. The results showed that the transition location moves toward the leading edge due to propeller slipstream. Increase in propeller rotational speed causes that the turbulent flow covers whole portion of the wing surface.