J. Bailly, Y. Delrieux

This paper presents the work performed at ONERA in the framework of the WorkPackage 5 of the Friendcopter European project. The objectives of this study consist in the research of optimized active twist laws to improve the performance for advancing flight configurations on the one hand, and reduce BVI noise in descent flight configurations on the other hand, on a BO105-like geometry model rotor with parabolic blade tip. The benefits in terms of power consumption by the main rotor and of noise levels are estimated. Rather limited power benefits are predicted (around 2% for a moderate advancing flight). The power reduction is mainly due to a decrease of the induced power, generated by an adapted distribution of the incidence angle modified by the addition of the active twist angle. A promising reduction of BVI noise (up to -7.4 dBA for a 7deg descent flight) is predicted. This benefit is due to the large effect of the active twist on the downward convection of the wake, which increases the blade-vortex miss-distances and the oblicity of the vortex lattices. The second step of this study is the research of optimized active flap laws on a BO105-like geometry rotor, with the same objectives. The power benefits are also rather limited (no more than -3%). The origin of the power benefit comes from a reduction of the profile power (which depends on the drag model used to account for the flap). The reduction of BVI noise levels is not as satisfactory as for the active twist concept. The indirect servo-flap effect is predominant for the rather soft in torsion studied rotor. The effect of convection is largely reduced due to the aeroelastic response of the rotor.

35th European Rotorcraft Forum 2009,

Conference Paper

englisch

21,0 x 29,7 cm, 13 Seiten

DGLR-Bericht, 2009, 2009-03, 35th European Rotorcraft Forum 2009 - Conference Proceedings; S.1-13; 2009; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn

NA

in getr. Zählung;

noise reduction, rotor aerodynamics

Bestellbar

2009