Accession Number : ADP004070

Title :   Active and Passive Shock/Boundary Layer Interaction Control on Supercritical Airfoils,

Corporate Author : DEUTSCHE FORSCHUNGS- UND VERSUCHSANSTALT FUER LUFT- UND RAUMFAHRT E V GOETTINGEN (GERMANY F R)

Personal Author(s) : Thiede,P. ; Krogmann,P. ; Stanewsky,E.

Report Date : AUG 1984

Pagination or Media Count : 13

Abstract : This paper presents experimental investigations which aimed at improving the off-design performance of supercritical airfoils by active or passive control of the shock/boundary layer interaction (SBLI) through boundary layer suction in the shock region or ventilation respectively. The experiments were carried out in the DFVLR 1m x 1m transonic windtunnel Gottingen, using the advanced supercritical airfoil VFW VA-2 designed to have a largely fixed shock position at off-design conditions. The basic model was equipped with an exchangeable control device within the shock region to allow measurements with either surface clean, suction through a single slot, double slot or perforated strip or ventilation through a double slot or perforated strip. The effectiveness of the different SBLI control methods is evaluated from surface pressure distribution, wake and boundary layer measurements as well as Schlieren observations. It is shown that local boundary suction in the shock region mainly delays the shock-induced separation to greater shock strength and stabilizes the shock in its rearward position up to higher incidence, resulting in substantial improvements in the airfoil characteristics at off-design conditions. Moreover, without any suction, favorable passive effect is observed by boundary layer ventilation on the double slot and perforated strip configurations with a plenum underneath. This leads to a weakening of the shock wave, offering a large potential for off-design drag reduction.

Descriptors :   *Supercritical airfoils, *Boundary layer control, Shock waves, Interactions, Suction, Flow separation, Passive systems, Perforation, Ventilation, Aerodynamic slots, Drag reduction, Experimental design, Wind tunnel models, West Germany

Distribution Statement : APPROVED FOR PUBLIC RELEASE