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A High Edgewise Rotor Using Circulation Control Only in the Reversed Flow Ares

I.C. Cheeseman, M.M.E. Soliman
The application of circulation control by blowing to edgewise rotors has been extensively investigated. Sufficient hardware has been constructed, principally in the USA, to conclude that the basic technology has been proved. Original circulation control applications were to stopped rotor aircraft which had higher productivity, to compensate for the increased complexity, and slightly lower disposable load relative to the conventional helicopter. The X-Wing was the most advanced and technologically challenging project attempted. Ten years ago it was realised at Southampton University that a thrust compounded helicopter fitted with a conventional bladed rotor adapted to utilise circulation control in the reversed flow region, might offer substantial performance improvements with relatively little technological risk. This paper describes that programme of work. To apply circulation control there must be no sharp trailing edge. An aerofoil flying backwards has just such a feature: this is what is normally the leading edge. Blowing slot(s) have been inserted in the nose which do not affect the aerofoils normal performance. Circulation control can therefore be combined with any advanced aerofoil or blade planform in order to provide positive and significant lift in the reversed flow region. To calculate the performance of such a rotor it was necessary to determine the aerofoil performance of a typical modern blade section fitted with leading edge circulation control. A wind tunnel model was constructed with a chord equal to that of a typical helicopter main rotor blade. To assist in positioning the slots on the aerofoil, the circulation control jet flow was modelled by the free vortex technique previously reported. A data file of two-dimensional lift, drag and pitching moment was produced which was used in the rotor performance program. Using RAE generated data for the aerofoil(s) operating normally, a helicopters performance was satisfactorily predicted. This program was then adapted to allow for reversed flow region circulation control as well as having provision for auxilliary propulsive thrust to be applied. The rotor advancing blade Mach number was not permitted to exceed that used by the conventional rotor.
17th European Rotorcraft Forum 1991, Berlin
Conference Paper
21,0 x 29,7 cm, 26 Seiten
DGLR-Bericht, 1991, 1991-08, 17th European Rotorcraft Forum Proceedings; S.507-532; 1991; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn
Stichworte zum Inhalt:
helicopters, rotors

Dieses Dokument ist Teil einer übergeordneten Publikation030:
17th European Rotorcraft Forum Proceedings