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Sound generation by vortex pairing in subsonic axisymmetric jets

Jiang, X and Avital, E J and Luo, K H and Jiang, Xi (2004) Sound generation by vortex pairing in subsonic axisymmetric jets. AIAA Journal, 42 (2). pp. 241-248. ISSN 0001-1452

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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 a reasonable agreement is observed between the predictions from the axisymmetric Lilley's equation and the DNS results.

Item Type: Article
Journal or Publication Title: AIAA Journal
Uncontrolled Keywords: SUPERSONIC COAXIAL JETS ; NOISE ; SCHEMES
Subjects:
Departments: Faculty of Science and Technology > Engineering
ID Code: 51196
Deposited By: ep_importer_pure
Deposited On: 21 Nov 2011 11:27
Refereed?: Yes
Published?: Published
Last Modified: 24 Jan 2014 05:23
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/51196

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