Active Flight Control using Distributed Bleed

摘要

A novel approach to aero-effected flight control of lifting surfaces usingdistributed active bleed is investigated in wind tunnel experiments.Aerodynamic control is achieved by large-area surface bleed of air that isdriven by pressure differences in flight and is regulated by low-powersurface-integrated louver actuators. The interaction between the bleed andcross flow is tailored to leverage the generation and regulation of vorticityconcentrations near the surface to locally alter an airfoil’s apparentaerodynamic shape and thereby the aerodynamic forces and moments. Anominally 2-D Clark-Y wind tunnel model is integrated with addressablearrays of piezoelectric louvers for leading and trailing edge bleed, and theresulting time-dependent forces and moment are measured over a wide rangeof angles of attack from pre- to post-stall using load cells. Induced changesin surface vorticity concentrations are measured using PIV. It is shown thatleading edge bleed leads to large variations in lift and pitching moment, andit can also be used to extend the stall margin using time-periodic louveractuation. At high angles of attack, leading-edge bleed actuation enables upto 50% variation in lift relative to the baseline without the use of externalcontrol surfaces.