On Belly-flap for Pitch Control at Transonic Airfoil

One of the issues about Blended-Wing-Body configuration(BWB) is its difficulty in pitch control due to the missing tail.To solve this problem,a novel pitch control surface,belly-flap,has been presented.In this paper,the feasibility of belly-flap being used as a transonic pitch control device for tailless configuration is investigated on a BWB in-body airfoil,using the computational fluid dynamic(CFD) method.The size,location and deflection angle of the flap are studied to detect their effect on the aerodynamic characteristics.The results reveal that the bubble separation due to the belly-flap can affect shock position on the upper surface of the airfoil and change the surface pressure distribution.By choosing appropriate geometry parameters,the load distribution can be improved to obtain significant pitch-up moment increment in a wide angle of attack with no lift-loss and less lift-drag ratio decrement.