W.R. Splettstoesser, K.-J. Schultz, R. Kube, T.F. Brooks, E.R. Booth Jr., G. Niesl, O. Streby

A model rotor acoustics test was performed to examine the benefit of higher harmonic control (HHC) of blade pitch to reduce blade-vortex interaction (BVI) impulsive noise. A dynamically scaled, four-bladed, rigid rotor model, a 40% replica of the B0-105 main rotor, was tested in the German Dutch Wind Tunnel (Deutsch-Niederländischer Windkanal, DNW). Acoustic measurements were made in a large plane underneath the rotor employing a traversing in-flow microphone array in the anechoic environment of the open test section. Noise characteristics and noise directivity patterns as well as vibratory loads were measured and used to demonstrate the changes when different HHC schedules (different modes, amplitudes, phases) were applied. Dramatic changes of the acoustic signatures and the noise radiation directivity with HHC phase variations are found. Compared to the baseline conditions (without HHC), significant mid-frequency noise reductions of locally 6 dB are obtained for low speed descent conditions where BVI is most intense. For other rotor operating conditions with less intense BVI there is less or no benefit from the use of HHC. Low frequency loading noise and vibratory loads, especially at optimum noise reduction control settings, are found to increase.

17th European Rotorcraft Forum 1991, Berlin

Conference Paper

englisch

21,0 x 29,7 cm, 13 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!

blade-vortex interaction, bo 105 helicopter, helicopters, rotors, wind tunnel

Bestellbar

1991