The aeroacoustics and aerodynamics of high-speed Coanda devices, Part 2: Effects of modifications for flow control and noise reduction
UNSPECIFIED. (1997) The aeroacoustics and aerodynamics of high-speed Coanda devices, Part 2: Effects of modifications for flow control and noise reduction. JOURNAL OF SOUND AND VIBRATION, 208 (5). pp. 803-822. ISSN 0022-460XFull text not available from this repository.
The paper describes two studies of the effects of flow control devices on the aerodynamics and aeroacoustics of a high speed Coanda flow that is formed when a supersonic jet issues from a radial nozzle and adheres to a tulip-shaped body of revolution. Shadowgraphy and other flow-visualization techniques are used to reveal the various features of the complex flow fields. The acoustic characteristics are obtained from far- and near-field measurements with an array of microphones in an anechoic chamber. First the effects of incorporating a step between the annular exit slot and the Coanda surface are investigated. The step is incorporated to ensure that the breakaway pressure is raised to a level well above the maximum operating pressure. It substantially increases the complexity of the flow field and acoustic characteristics. In particular, it promotes the generation of two groups of discrete tones. A theoretical model based on a self-generated feedback loop is proposed to explain how these tones are generated. The second study investigates the effects of replacing the annular exit slot with a saw-toothed one with the ain of eliminating the discrete tones and thereby substantially reducing the level of noise generated. (C) 1997 Academic Press Limited.
|Item Type:||Journal Article|
|Subjects:||T Technology > TA Engineering (General). Civil engineering (General)
T Technology > TJ Mechanical engineering and machinery
|Journal or Publication Title:||JOURNAL OF SOUND AND VIBRATION|
|Publisher:||ACADEMIC PRESS LTD|
|Date:||18 December 1997|
|Number of Pages:||20|
|Page Range:||pp. 803-822|
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