Analysis Regarding Variable Cambering with Spoiler Tracking: Effect of the Flap Hinge Line Location on the Aerodynamic at Transonic Speeds

Kurzfassung

Variable cambering (VC) is a well proven method to help provide beneficial aerodynamics in terms of drag reduction for a wide range of the flight envelope. In combination with application of laminar flow (NLF) up to the shock VC can be even used to decrease skin friction drag. Because of the ability of VC to serve as a baseline technology providing benefits to other drag reduction technologies it is of growing interest for commercial applications again. While VC in general is fairly documented in literature its application to airfoils with shock locations at the adaptive surface providing extended laminar flow up to that point is not. This work focuses on the aerodynamic effects of flap hinge line movement with spoiler tracking at transonic speeds. The work was done within the LuFoV-1 project LDAinOp (Low Drag Aircraft in Operation). In addition to a reference configuration 8 different hinge line positions are discussed. It will be shown that, when applying VC in order to move the shock to its desired location, the hinge line position significantly affects the shock because of curvature effects at the wing/spoiler junction. Furthermore it will be shown that, if the shock is located directly at the junction at design conditions, it is even possible to reduce the wave drag by both upward and downward flap deflection. This shows the importance of taking the hinge line position into account when designing adaptive wing configurations which are utilizing movable devices as VC surfaces.