Influences of trailing-edge synthetic jets on longitudinal aerodynamic characteristics of a flying wing aircraft

Abstract

For realizing the nice aerodynamic maneuverability of flying wing aircrafts (FWAs), a longitudinal aerodynamic control technology based on circulation control (CC) using trailing-edge synthetic jet actuators was proposed. Influences on longitudinal characteristics of a FWA were investigated. Results show that synthetic jets could improve the lift, drag, and nose-down moment, having potential of flight control at entire area of attack of angles (AOAs). Cl increment dips and then rises with the growth of AOAs, reaching the minimum at AOA of 12°. The maximum percentage of Cl enhancement and ΔCl/Cμ is separately 64.5% and 50.74%, respectively. Before 12°, synthetic jets could narrow the area of “dead zone,” improve flow velocities along the upper surface, and then move the trailing-edge separation point and the leading-edge (LE) stagnation point downward, enhancing the circulation. Moreover, synthetic jets grow rapidly through entrainment of the local flow, leading to the improvement of valid camber and, hence, the increase in Cl. CC efficiency decreases with the augmentation of AOAs, and leading-edge vortex (LEV) is weakened, causing the drop of Cl increment. After 12°, synthetic jets could enhance the longitudinal velocity of LEV and reduce the swirling number, improving the strength and stability of LEV, which results in larger suction near the leading edge. Moreover, the strengthened LEV could promote flow mixing and then weaken reverse pressure gradients along the wing section, thus improving flow velocities and CC efficiency at the wing section. It is above two factors that make Cl increment rise after 12°.