Research>Flow control>Manoeuvre effectors>Flow Control Spoiler Systems

Overview

Spoilers are, literally, devices that 'spoil' a flow by disrupting the smooth flow of air over a surface. The loss in total pressure associated with 'spoiled' flow causes an increase in drag. Additionally, the adverse pressure gradient produced by the spoiler causes the flow to separate at, or slightly ahead of the spoiler. If the spoiler is on a lifting surface, flow separation leads to loss of circulation and hence reduction in lift.

Promotion of separation is usually understood to be an easier problem that delay of separation, however, if using flow control spoilers instead of conventional hinged surfaces, then careful consideration of the energy requirements is needed. This leads to the concept of receptivity: if the amount of energy (or mass flow or momentum) required is to be minimised, then the flow must be receptive to small disturbances. An unreceptive flow is one that is very stable and that requires a large disturbance to change it from that stable state. In partnership with QinetiQ, the concept of a compliant aerodynamic technology wing section has been developed. This wing section has a region towards the trailing edge that is attached, but very close to separation, i.e. the surface shear stress is positive, but very close to zero.

The FCSS work is continuing through the FLAVIIR project, where it is tied in with developing a wireless aircraft: very low power flow control spoilers could potentially be powered off local batteries hence removing the need for wired power supply (coupled with wireless communications)

Publications

Pilmoor, M., Crowther, W.J., and Wood, N.J., ‘Development of a Dynamic Wind Tunnel Model for Demonstration of Flow Control Maneuver Effectors’, AIAA-2006-3507