F. Holste, W. Neise

An experimental investigation is described to explore the dominant sound generation mechanisms of the tonal noise components of the MTU-CRISP propfan model (Motoren- und Turbinen-Union Miinchen, Counter Rotating Integrated Shrouded fropfan). For this purpose, the sound field in the exit plane is measured using 1/4 inch microphones with nose cone. The measured pressure pattern is resolved into a distribution of acoustic duct modes (spinning modes) for the blade passing frequency and its harmonics. The model propfan is operated in a wind tunnel flow environment. Initial tests proved that the presence of the microphone probes in the exit flow does not interfere with the sound pressure distribution. Experimental results of the mode distributions show that the blade pa8sing frequency component is generated mainly by the interaction mechanisms between the rotors and the struts and/or by a transformation of acoustics modes at the struts. For all higher harmonics, the interaction between the two counter rotating rotors is the main noise source. The relative imponance of the various interaction mechanisms is discussed for various shroud geometries, blade profiles, blade stagger angles, thrust conditions, angles of incidence, and wind tunnel speeds.

DGLR/AIAA 14th Aeroacoustics Conference, 1992

Conference Paper

englisch

21,0 x 29,7 cm, 10 Seiten

DGLR-Bericht, 1992, 1992-03, DGLR/AIAA 14th Aeroacoustics Conference - Proceedings; S.826-835; 1992; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn

NA

aeroacoustics

Bibliothek

1992