A higher harmonic control test in the DNW to reduce impulsive BVI noise

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A higher harmonic control test in the DNW to reduce impulsive BVI noise

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

A model rotor acoustic test was performed to examine the benefit of higher harmonic control (HHC) of blade pitch to reduce blade-vortex interaction (BVI) impulsive noise. A 40-percent dynamically scaled, four-bladed model of a BO-105 main rotor was tested in the German-Dutch Wind Tunnel (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 as much as 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.

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Dokumentinformationen

Titel :

A higher harmonic control test in the DNW to reduce impulsive BVI noise

Weitere Titelangaben:

Ein Regelungstest mit den höher Harmonischen im DNW (Deutsch-Holländischer Windkanal) zur Reduktion von impulsartig auftretenden Flügel-Wirbel-Wechselwirkungs-Geräuschen

Beteiligte:

Splettstoesser, W.R. (Autor:in) / Schultz, K.J. (Autor:in) / Kube, R. (Autor:in) / Brooks, T.F. (Autor:in) / Booth, E.R. jun. (Autor:in) / Niesl, G. (Autor:in) / Streby, O. (Autor:in)

Erschienen in:

Journal of the American Helicopter Society ; 39 , 4 ; 3-13

Erscheinungsdatum :

1994

Format / Umfang :

11 Seiten, 13 Bilder, 23 Quellen

ISSN :

0002-8711

Medientyp :

Aufsatz (Zeitschrift)

Format :

Sprache :