I. Papavassiliou, P.P. Friedmann, C. Venkatesan

A nonlinear coupled rotor/flexible fuselage analysis has been developed and used to study the effects of higher harmonic blade pitch control on the vibratory hub loads and fuselage acceleration levels. Previous results, obtained with this model have shown that conventional higher harmonic control (HHC) inputs aimed at hub shear reduction cause an increase in the fuselage accelerations and viseversa. It was also found that for simultaneous reduction of hub shears and fuselage accelerations, a pitch input representing a combination of two higher harmonic components of different frequencies was needed. Subsequently, it was found that this input could not be implemented through a conventional swashplate. This paper corrects a mistake originally made in the representation of the multiple frequency pitch input and shows that such a pitch input can be only implemented in the rotating reference frame. A rigorous mathematical solution is found, for the pitch input in the rotating reference frame, which produces simultaneous reduction of hub shears and fuselage acceleration. New insight on vibration reduction in coupled rotor/fuselage systems is obtained from the sensitivity of hub shears to the frequency and amplitude of the open loop HHC signal in the rotating reference frame. Finally the role of fuselage flexibilty in this class of problems is determined.

17th European Rotorcraft Forum 1991, Berlin

Conference Paper

englisch

21,0 x 29,7 cm, 44 Seiten

DGLR-Bericht, 1991, 1991-08, 17th European Rotorcraft Forum Proceedings; 1991; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn

NA

Dieser Aufsatz ist nicht Teil der Veröffentlichung!

rotor blades, rotor body interactions, vibration

Bestellbar

1991