Inverted Jet Spoilers for Aerodynamic Control

Abstract

This paper reviews concepts for flow control based on jet spoilers and presents a new device based on the jet principle for application to fixed-wing aircraft. The new concept relies on the naturally blown inverse spoiler. Thejet is blown parallel to the surface and points against the freestream. The theoretical basis of the device is presented. Calculations are performed with a Navier-Stokes program to investigate the key design parameters. These parameters include the spoiler deflection (equal or differential), the position of the hinge points, the shape of the bypass channel, the effects of backward- and forward-facing steps in a partial deflection, and the nature and magnitude of the control forces. A comparison is done with conventional inlay spoilers. Finally, a multidimensional optimization has been carried out to study the combined effects of hinge position, deflection, and spoiler length. Optimal configurations with respect to jet momentum and drag coefficient have been analyzed.