High Lift/Low Drag Thick Subsonic Griffith/Goldschmied Airfoil with Integrated Cross-flow Fan Propulsion

摘要

A concept for synergistically integrating a cross-flow fan (CFF) with a thick subsonic airfoil for lift augmentation and thrust production is proposed. The design partially embeds a cross-flow fan atop at the maximum thickness location of a modified 35% thick Griffith/Goldschmied airfoil equipped with a modular trailing edge "jet-flap." The embedded CFF effectively provides a combined suction blowing effect along the wing suction surface to achieve high performance from the traditional Griffith/Goldschmied airfoil. Low momentum flow is ingested by the CFF via boundary layer inlet, energized, and expelled as a jet to re-attach the flow after the maximum thickness location. The newly energized flow allows for aggressive rear airfoil curvature to generate static pressure thrust and also drag reduction by filling the wake. In addition to the competitive cruise performance as a result of the concave trailing edge surface in the original Griffith/Goldschmied airfoil, the trailing edge surface can be converted to a circulation control airfoil by inverting or flexing it to form a convex jet-flap surface. The use of such a technique allows lift coefficients in excess of 12 to be achieved at zero angle-of-attack. Concept feasibility is verified using the commercial CFD software Fluent to perform RANS 2D unsteady simulations of the airfoil-propulsor combination.