Aeroacoustics of duct junction flows merging at different angles

Lam, G. C.Y.; Leung, R. C.K.; Tang, S. K.

Abstract

This paper reports an exploratory study of the aeroacoustics of a merging flow at a duct junction with the same width in all branches and different merging angles. The focus is put on the acoustic generation due to the flow unsteadiness. The study is carried out by the direct aeroacoustic simulation (DAS) approach, which solves the unsteady compressible Navier-Stokes equations and the perfect gas equation of state simultaneously using the conservation element and solution element (CE/SE) method. The Mach number based on the maximum inlet velocity of side branch is 0.1 and the Reynolds number of the flow based on duct width and this velocity is 2.3×105. The numerical simulations are performed in two dimensions and the aeroacoustics at different merging angles (30°, 45°, 60° and 90°) are studied. Both the levels of unsteady interactions of merging flow structures and the efficiency of the acoustic generation are observed to increase with the merging angles, where the increase in acoustic efficiency can be up to three orders of magnitude. The major acoustic source is found to be the fluctuating wall pressure induced by the flow unsteadiness in the downstream branch. A scaling law between the wall fluctuating force and the acoustic efficiency is also derived.

Citation

Lam, G. C., Leung, R. C., & Tang, S. K. (2014). Aeroacoustics of duct junction flows merging at different angles. Journal of Sound and Vibration, 333(18), 4187-4202. https://doi.org/10.1016/j.jsv.2014.04.045

• Journal Article Type: Article
• Acceptance Date: Apr 22, 2014
• Online Publication Date: May 14, 2014
• Publication Date: Sep 1, 2014
• Deposit Date: Jul 11, 2022
• Journal: Journal of Sound and Vibration
• Print ISSN: 0022-460X
• Electronic ISSN: 1095-8568
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 333
• Issue: 18
• Pages: 4187-4202
• DOI: https://doi.org/10.1016/j.jsv.2014.04.045
• Public URL: https://hull-repository.worktribe.com/output/4015879