| タイトル | Direct measurement of sound sources in air jets using the crossed beam correlation technique |
| 著者（英） | Grosche, F. R.; Damkevala, R. J.; Guest, S. H. |
| 著者所属（英） | NASA Marshall Space Flight Center |
| 発行日 | 1974-03-01 |
| 言語 | eng |
| 内容記述 | Properties of density fluctuations were measured in the turbulent regions of a 2.54 cm air jet, at M = 0.7, 1.0 and 1.94. After calibration tests, it was found that the absorption of infrared radiation at 4.3 microns by the naturally present quantities of carbon-dioxide in air was directly proportional to the air density if a sufficiently wide bandpass (0.08 microns) was used. Moreover, regions of the band could be selected that adequately discriminated against temperature variations. The cross-correlation of two such beams intersecting in the jet gave a measure of the local properties at the intersection point. A derivation is presented relating the local density correlation function to the self and shear generated noise in the far field of the jet. The measured correlations are used to predict the axial distribution of source strengths and the spectrum of noise due to a unit volume of turbulence. |
| NASA分類 | AIRCRAFT |
| レポートNO | 74N22645 |
| 権利 | No Copyright, Distribution within the U.S. granted by agreement |
| URI | https://repository.exst.jaxa.jp/dspace/handle/a-is/269845 |
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