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Communication Dans Un Congrès Année : 1999

Measurement of sound radiated by turbulent wall jets past singularities

Résumé

Sound radiated by high‐speed turbulent wall jets past backward facing steps or shallow cavities is investigated experimentally. Both aerodynamic (laser Doppler and hot wire anemometry) and acoustic measurements (far‐field directivity, spectra, and source localizations) are performed. Source localizations show that a backward facing step is a major sound source. Far‐field measurements show that it has a strong upstream directivity and radiates in the medium frequency range. Aerodynamical results and an acoustic parametric study suggest that the source is due to the diffraction of the separated shear layer eddies by the sharp edge of the step: this is qualitatively confirmed by existing diffraction models. A shallow cavity (with length exceeding seven times the depth) has a strong downstream and upstream directivity: it can be regarded as a superposition of two acoustically independent sources, a backward facing and an upward facing step. In particular for such cavities and for Reynolds numbers (based on cavity depth) ranging from 40 000 to 470 000 no feedback mechanism and no cavity resonances are observed. [Work supported by the French Ministère des transports.]
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Dates et versions

hal-03360688 , version 1 (30-09-2021)

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  • HAL Id : hal-03360688 , version 1

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Marc C. Jacob, Vincent Gradoz, Alain Louisot, Daniel Juvé, Sylvie Guerrand. Measurement of sound radiated by turbulent wall jets past singularities. Joint ASA-EEA Meeting, Mar 1999, Berlin, Germany. ⟨hal-03360688⟩
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