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Mach wave radiation by mixing layers. Part II: analysis of the source field

Mach wave radiation by mixing layers. Part II: analysis of the source field
Mach wave radiation by mixing layers. Part II: analysis of the source field
In Part II a large-scale sound source in a time-developing planar free mixing layer is studied using an acoustic analogy approach. It is shown that only the non-compact character of the source resembles well the character of the corresponding source in a spatially developing flow. A model based on a continuous assembly of wave packets is derived and applied to direct numerical simulation results of two supersonic time-developing mixing layers undergoing transition to turbulence. The analysis predicts two distinctive dominant Mach wave sources in agreement with the direct analysis of Part I. The first dominates during the stage of the ¤-vortex structure and the second just prior to the final breakdown to a fine-scale structure. The convective velocity of the second Mach wave source is higher than the first and thus its Mach angle of radiation is higher. The second source has a reduced strength at the higher free-stream Mach number. Directivity and frequency spectra compare well with the results of Part I, demonstrating that the assumptions inherent in the analogy are quite reasonable
0935-4964
91-108
Avital, E.J.
37c1edd0-b9c3-4751-be1e-c61505671ae8
Sandham, N.D.
0024d8cd-c788-4811-a470-57934fbdcf97
Luo, K.H.
1c9be6c6-e956-4b12-af13-32ea855c69f3
Avital, E.J.
37c1edd0-b9c3-4751-be1e-c61505671ae8
Sandham, N.D.
0024d8cd-c788-4811-a470-57934fbdcf97
Luo, K.H.
1c9be6c6-e956-4b12-af13-32ea855c69f3

Avital, E.J., Sandham, N.D. and Luo, K.H. (1998) Mach wave radiation by mixing layers. Part II: analysis of the source field. Theoretical and Computational Fluid Dynamics, 12 (2), 91-108. (doi:10.1007/s001620050101).

Record type: Article

Abstract

In Part II a large-scale sound source in a time-developing planar free mixing layer is studied using an acoustic analogy approach. It is shown that only the non-compact character of the source resembles well the character of the corresponding source in a spatially developing flow. A model based on a continuous assembly of wave packets is derived and applied to direct numerical simulation results of two supersonic time-developing mixing layers undergoing transition to turbulence. The analysis predicts two distinctive dominant Mach wave sources in agreement with the direct analysis of Part I. The first dominates during the stage of the ¤-vortex structure and the second just prior to the final breakdown to a fine-scale structure. The convective velocity of the second Mach wave source is higher than the first and thus its Mach angle of radiation is higher. The second source has a reduced strength at the higher free-stream Mach number. Directivity and frequency spectra compare well with the results of Part I, demonstrating that the assumptions inherent in the analogy are quite reasonable

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Published date: September 1998

Identifiers

Local EPrints ID: 72005
URI: http://eprints.soton.ac.uk/id/eprint/72005
ISSN: 0935-4964
PURE UUID: b5956b08-0dbd-46fa-bf47-76609fb2e938
ORCID for N.D. Sandham: ORCID iD orcid.org/0000-0002-5107-0944

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Date deposited: 14 Jan 2010
Last modified: 03 Dec 2019 01:56

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Contributors

Author: E.J. Avital
Author: N.D. Sandham ORCID iD
Author: K.H. Luo

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