T. Lölgen, G. Neuwerth

The noise emission of counter rotating propellers (CRP) was investigated theoretically and by experiments giving special emphasis to the influence of CRP inflow distortions and to the aerodynamic interaction between the rotors. Experiments were conducted using a 0.6 m scale model CRP with 5 blades on the front rotor and 6 blades on the rear rotor in an open-jet wind tunnel for take off and landing conditions. The emitted sound power was measured in the wind tunnel reverberation room, measurements of noise directivity were performed in the acoustic nearfield. The velocity distributions in the inflow and downwash of the CRP were analyzed as well as the flow between the rotor planes. Additional noise power measurement were conducted using a lft. scale model 8x8 CRP. A system of computer programs has been developed to predict the emitted noise fields starting with the distorted flow and calculating steady and unsteady blade loads as a function of the radial positions. Measurements of the noise levels and the sound spectrum are in good agreement with the theoretical predictions.

DGLR/AIAA 14th Aeroacoustics Conference, 1992

Conference Paper

englisch

21,0 x 29,7 cm, 9 Seiten

DGLR-Bericht, 1992, 1992-03, DGLR/AIAA 14th Aeroacoustics Conference - Proceedings; S.325-333; 1992; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn

NA

aeroacoustics

Bibliothek

1992