Forebody Flow Control for Extended High-Angle-of-Attack Maneuvers

摘要

Tangential forebody blowing for the purpose of yaw control has been investigated on a 6% generic fighter model in the 2.1 x 1.5-m low-speed wind tunnel at the University of Bath. Force and moment data were obtained from a sting-mounted, six-component strain gauge balance over an angle-of-attack range of -10 to 120 deg. The tangential blowing slots were incorporated into a vacuum-formed, plastic forebody, which contained two independent plenum chambers. The geometry of the slots was optimized for high-angle-of-attack operation based on results from previous research. Three different forebodies were used to investigate the effects of different azimuthal slot positions. At angles of attack beyond 60 deg, all of the slot locations were shown to produce significant yawing moments, even when compared to conventional yaw control at low angles. This control moment did not decay at the maximum angle of attack tested, which suggests that the envelope of control could be extended farther. The concept remained effective even at conditions where the flow along the longitudinal body axis was reversed. At angles of attack appropriate for normal cruise operation, takeoff, or landing, all slot locations proved effective in producing yawing moments. Consequently, tangential forebody blowing may prove capable of replacing conventional fin and rudder combinations in establishing weathercock stability.