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Title: 一様流中に置かれたNACA0012翼から発生する離散周波数騒音の発生機構に関する実験的研究
Other Titles: Experimental Investigation into the Mechanism of Discrete Frequency noise (DFN) Generation from a NACA 0012 Blade
Authors: 林, 秀千人 / 深野, 徹 / 児玉, 好雄
Authors (alternative): Hayashi, Hidechito / Fukano, Tohru / Kodama, Yoshio
Issue Date: 25-Mar-1993
Publisher: 日本機械学会
Citation: 日本機械学會論文集. B編 59(559) p.802-806 1993
Abstract: An experimental investigation was made into the mechanism of discrete frequency noise ( DFN )generation from a NACA 0012 blade placed in a uniform oncoming flow. It was clarified that DFN was generated when the boundary layer on the blade surface was laminar and separated at the location upstream of the trailing edge. A dead air region was formed just after the trailing edge of the blade. Therefore a Karman vortex street occurred. Meanwhile we could not observe a close relationship between the existence of a separation bubble and the generation of DFN. That is, DFN was generated even when the attack angle of the flow was nearly zero and no separation bubble was observed. When a separation bubble existed, the boundary layer became turbulent and the flow did not separate up to the trailing edge, so a dead air region was not formed behind the blade, which resulted in the disappearance of DFN. The prediction of the sound pressure level of DFN generated from this stream lined blade by Fukano's theory for a flat plate model agreed well with the measured value.
Keywords: Vortex / Aerodynamic Acoustics / Wake / Blade / Separation / Unsteady Flow
URI: http://hdl.handle.net/10069/6705
ISSN: 03875016
Type: Journal Article
Text Version: publisher
Appears in Collections:Articles in academic journal

Citable URI : http://hdl.handle.net/10069/6705

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