Prediction of breakout noise from a rectangular duct with compliantwalls

B, Venkatesham and Tiwari, M and Munjal, M L (2011) Prediction of breakout noise from a rectangular duct with compliantwalls. International Journal of Acoustics and Vibrations, 16 (4). pp. 180-190. ISSN 1027-5851

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Abstract

Breakout noise from HVAC ducts is important at low frequencies, and the coupling between the acoustic waves and the structural waves plays a critical role in the prediction of the transverse transmission loss. This paper describes the analytical calculation of breakout noise by incorporating three-dimensional effects along with the acoustical and structural wave coupling phenomena. The first step in the breakout noise prediction is to calculate the inside duct pressure field and the normal duct wall vibration by using the solution of the governing differential equations in terms of Green's function. The resultant equations are rearranged in terms of impedance and mobility, which results in a compact matrix formulation. The Green's function selected for the current problem is the cavity Green's function with modification of wave number in the longitudinal direction in order to incorporate the terminal impedance. The second step is to calculate the radiated sound power from the compliant duct walls by means of an "equivalent unfolded plate" model. The transverse transmission loss from the duct walls is calculated using the ratio of the incident power due to surface source inside the duct to the acoustic power radiated from the compliant duct walls. Analytical results are validated with the FE-BE numerical models.

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IITH Creators:

IITH Creators	ORCiD
B, Venkatesham	http://orcid.org/0000-0003-3651-513X

Item Type:

Article

Uncontrolled Keywords:

Acoustic power; Analytical calculation; Analytical results; Duct walls; Governing differential equations; HVAC ducts; Incident power; Longitudinal direction; Low frequency; Matrix formulation; Noise predictions; Pressure field; Radiated sound; Rectangular ducts; Surface sources; Terminal impedance; Three dimensional effect; Transmission loss; Wave coupling; Wave numbers

Subjects:

Physics > Sound, light and Heat

Divisions:

Department of Mechanical & Aerospace Engineering

Depositing User:

Team Library

Date Deposited:

29 Oct 2014 08:56

Last Modified:

21 Sep 2017 06:14

URI:

http://raiithold.iith.ac.in/id/eprint/520