J.M. Mendoza, K.K. Ahuja

The results of an experimental investigation of cavity flows are presented. The effects of varying the width (spanwise dimension) of the cavity, while holding fixed the length and depth dimensions (i.e., LID). on the cavity feedback frequencies, noise levels, and span-wise coherence of the excited instability wave were investigated. A wall jet issuing from a rectangular nozzle was used to simulate flows of the cavity. All test conditions consisted of a shallow cavity (LID = 3.75), with variable width dimensions, and freestream Mach numbers ranging from low subsonic to sonic. The parameter L/W (the· ratio of cavity length to cavity width) was used to categorize two-dimensional and three-dimensional cavity flows as L/W < 1 and L/W > l, respectively. This classification was borne out in our investigation. The results of this investigation indicate that for a fixed LID and freestream Mach number: (1) the frequencies are unaffected by the change in L/W; (2) for L/W > 1, the noise levels are reduced by as much as 15 dB; (3) L/W = 1 appears to be a cut-off between 2-D and 3-D flow, and (4) tuft flow visualization and span-wise coherence measurements indicate that for L/W > 1 the span-wise coherence of the excited instability wave is reduced. This reduction is indeed associated with the lower tonal levels of the noise spectra.

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.403-409; 1995; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn

NA

aeroacoustics

Bibliothek

1995