Wind Tunnel Measurements on Details of Laminar Wings

Abstract

Flow visualizations using oil in a wind tunnel as well as in free flight have been conducted to show whether or not the pressure field of the fuselage does influence the position of laminar-turbulent transition on a glider wing. Within the wind tunnel campaign, valuable experience could be gained in visualization of laminar separation bubbles under free flight Reynolds numbers. In free flight, it could be shown that the fuselage does not influence the boundary layer of the wing to a significant spanwise extent. Moreover, winch launch is an appropriate way to conduct oil visualization in free flight. It even shows some significant and unexpected advantages. Moreover, the effect of details like fences and aileron linkage fairings on parasite drag has been investigated under laboratory conditions. Fairings have been applied in closed, open and even cut configuration on the suction as well as on the pressure side of the airfoil. All details are clearly visible in the wake bucket, however, their effect on total drag can be considered rather small.