Investigation of slat heel effect on the flow field over multi-element aerofoils

This paper presents results obtained from an experimental study of the flow field over a multi-element aerofoil which incorporates either a conventional or an advanced slat. Detailed measurements of the mean flow and turbulent quantities over a multi-element aerofoil model equipped with either type of slat have been made in a wind tunnel using stationary and flying hot-wire (FHW) probes. The performance of the two slats at two angles of attack, alpha = 10degrees and 20degrees, were investigated and compared with each other. The results showed a better performance for the advanced slat in terms of the mean velocity field and hence an increase in the lift performance. The advantage of the advanced slat was more pronounced for the multi-element aerofoil placed at the higher angle of attack, i.e., 20degrees. These findings were substantiated by the Reynolds stresses measured over the multi-element aerofoil, with the conventional slat exhibiting higher values compared with its advanced slat counterpart. Both the mean velocity and Reynolds stress results clearly demonstrated that the conventional slat had a lower stall margin than the advanced slat. (C) 2002 Elsevier Science Inc. All rights reserved.