Research>Flow Control >Separation Control

Overview

The flow is said to be 'attached' to a body when the flow follows the contour of the body closely. When the flow fails to follow the contour of the body closely, it is said to be a 'separated' flow. For attached flows, the shear layer between the surface and the free stream (the boundary layer) remains attached to the surface on which it is developing. In a separated flow, the boundary layer leaves the surface and becomes a free shear layer. The separation point is the place where the boundary layer leaves the surface. Given a separated flow over a surface, the goal of separation control is to move the point at which separation occurs in a downstream direction, i.e. reduce the extent of separated flow. For a bluff (non-streamlined body), separation delay will lead to a reduction in drag. For a lifting surface, the goal is usually to either in crease the maximum lift available, e.g. for flap systems, or to increase the overall lift to drag ratio of the body, e.g. for better cruising performance.

Publications

Sunneechurra, K., Crowther, W.J., 'Problems with Leading-Edge Flow Control Experiments', Journal of Aircraft, Vol. 44, No. 3, May–June 2007, pp 1052-1054

Erbsloeh, S.D., Crowther, W.J., ‘Control of Compressor Face Total Pressure Distortion on a High Bypass Turbofan Intake Using Air-Jet Vortex Generators’, AIAA-2004-2206, 2^nd AIAA Flow Control Conference, Portland, Oregon, June 28-1, 2004.

Crowther, W.J., ‘Control of separation on a trailing edge flap using air jet vortex generators’, Journal of Aircraft, Vol. 43, No. 5, pp1589,1592, September 2006.

Flow separation control work