O. Bschorr, K. Schmidts, P. Faulhaber

Since there is a strong relation between the deliberated thrust effect and the noise generation of the propeller, noise reduction by means of active control seem to be most promising. Theoretical investigations show the high potential of this method. A pneumatic antisound generator has been developed, which radiates the necessary acoustic power at the low frequencies of propeller noise. The antisound generator consists of a fan to provide the necessary air load, a siren to modulate the air flow and an acoustic resonator to amplify the sound emission. Interference experiments where made on a ground-fixed aircraft at propeller full speed with the developed antisound generator. For the fundamental propeller harmonic level reductions of more then 15 dB were achieved, thus the second harmonic determined the overall level. The A-weighted overall level has been reduced of about 4.5 dB(A). In further experiments the antisound generator has been adjusted to meet noise reductions in different directions at the same time.

First Joint CEAS/AIAA Aeroacoustics Conference, München, 1995

Conference Paper

englisch

21,0 x 29,7 cm, 7 Seiten

DGLR-Bericht, 1995, 1995-01, First Joint CEAS/AIAA Aeroacoustics Conference - Proceedings; S.205-211; 1995; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn

NA

aeroacoustics

Bibliothek

1995