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Sound generation by vortex pairing in subsonic axisymmetric jets

Sound generation by vortex pairing in subsonic axisymmetric jets
Sound generation by vortex pairing in subsonic axisymmetric jets
Direct numerical simulation (DNS) and an acoustic analogy are used to investigate the sound generation by vortex pairing in idealized subsonic axisymmetric jets. The detailed sound source structure is provided by the DNS. The acoustic analogy is based on solving the nonlinearized Lilley’s third-order wave equation in the time-space domain. A numerical algorithm for solving Lilley’s equation is developed, in which the sound field is simulated simultaneously with the source field calculation. The computational domain includes both the near field and a portion of the acoustic far field. Effects of a coaxial secondary jet stream and the jet-to-ambient temperature ratio on the sound generation from an axisymmetric jet are investigated. It is shown that the sound source has a long axial distribution in the streamwise direction with the strongest source located near the end of the jet potential core where vortex pairing/merging occurs, and the radiated sound field is highly directive. It is also found that the secondary jet stream reduces the sound source size; therefore, the sound radiation from the coaxial jets is lower than that from the single jet. The hot jet simulation shows that increasing the jet-to-ambient temperature ratio leads to a smaller and weaker sound source, but does not lead to a weaker sound field. For the sound field areasonable agreement is observed between the predictions from the axisymmetric Lilley’s equation and the DNS results.
0001-1452
241-248
Jiang, X.
5c8e8d8e-59e2-45c5-a8de-b13eb7295048
Avital, E.J.
37c1edd0-b9c3-4751-be1e-c61505671ae8
Luo, K.H.
1c9be6c6-e956-4b12-af13-32ea855c69f3
Jiang, X.
5c8e8d8e-59e2-45c5-a8de-b13eb7295048
Avital, E.J.
37c1edd0-b9c3-4751-be1e-c61505671ae8
Luo, K.H.
1c9be6c6-e956-4b12-af13-32ea855c69f3

Jiang, X., Avital, E.J. and Luo, K.H. (2004) Sound generation by vortex pairing in subsonic axisymmetric jets. AIAA Journal, 42 (2), 241-248. (doi:10.2514/1.1373).

Record type: Article

Abstract

Direct numerical simulation (DNS) and an acoustic analogy are used to investigate the sound generation by vortex pairing in idealized subsonic axisymmetric jets. The detailed sound source structure is provided by the DNS. The acoustic analogy is based on solving the nonlinearized Lilley’s third-order wave equation in the time-space domain. A numerical algorithm for solving Lilley’s equation is developed, in which the sound field is simulated simultaneously with the source field calculation. The computational domain includes both the near field and a portion of the acoustic far field. Effects of a coaxial secondary jet stream and the jet-to-ambient temperature ratio on the sound generation from an axisymmetric jet are investigated. It is shown that the sound source has a long axial distribution in the streamwise direction with the strongest source located near the end of the jet potential core where vortex pairing/merging occurs, and the radiated sound field is highly directive. It is also found that the secondary jet stream reduces the sound source size; therefore, the sound radiation from the coaxial jets is lower than that from the single jet. The hot jet simulation shows that increasing the jet-to-ambient temperature ratio leads to a smaller and weaker sound source, but does not lead to a weaker sound field. For the sound field areasonable agreement is observed between the predictions from the axisymmetric Lilley’s equation and the DNS results.

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Published date: February 2004

Identifiers

Local EPrints ID: 23062
URI: http://eprints.soton.ac.uk/id/eprint/23062
ISSN: 0001-1452
PURE UUID: 9c1e6ff0-ee50-4577-8f8a-0954abf14cc8

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Date deposited: 23 Mar 2006
Last modified: 15 Mar 2024 06:43

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Contributors

Author: X. Jiang
Author: E.J. Avital
Author: K.H. Luo

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