JAXA Repository / AIREX 未来へ続く、宙(そら)への英知

このアイテムに関連するファイルはありません。

タイトルAcoustics of Jet Surface Interaction-Scrubbing Noise
本文(外部サイト)http://hdl.handle.net/2060/20150000743
著者(英)Khavaran, Abbas
著者所属(英)NASA Glenn Research Center
発行日2014-06-16
言語eng
内容記述Concepts envisioned for the future of civil air transport consist of unconventional propulsion systems in the close proximity of the structure or embedded in the airframe. While such integrated systems are intended to shield noise from community, they also introduce new sources of sound. Sound generation due to interaction of a jet flow past a nearby solid surface is investigated here using the generalized acoustic analogy theory. The analysis applies to the boundary layer noise generated at and near a wall, and excludes the scattered noise component that is produced at the leading or the trailing edge. While compressibility effects are relatively unimportant at very low Mach numbers, frictional heat generation and thermal gradient normal to the surface could play important roles in generation and propagation of sound in high speed jets of practical interest. A general expression is given for the spectral density of the far field sound as governed by the variable density Pridmore-Brown equation. The propagation Greens function is solved numerically for a high aspect-ratio rectangular jet starting with the boundary conditions on the surface and subject to specified mean velocity and temperature profiles between the surface and the observer. It is shown the magnitude of the Greens function decreases with increasing source frequency andor jet temperature. The phase remains constant for a rigid surface, but varies with source location when subject to an impedance type boundary condition. The Greens function in the absence of the surface, and flight effect are also investigated.
NASA分類Acoustics
レポートNOGRC-E-DAA-TN15616
権利Copyright, Distribution under U.S. Government purpose rights
URIhttps://repository.exst.jaxa.jp/dspace/handle/a-is/60660


このリポジトリに保管されているアイテムは、他に指定されている場合を除き、著作権により保護されています。