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Improved tuning of the extended concentric tube resonator for wide-band transmission loss

Ramya, E and Munjal, ML (2014) Improved tuning of the extended concentric tube resonator for wide-band transmission loss. In: NOISE CONTROL ENGINEERING JOURNAL, 62 (4). pp. 252-263.

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Official URL: http://dx.doi.org/10.3397/1/376225


Transmission loss (TL) of a simple expansion chamber (SEC) consists of periodic domes with sharp troughs. This limits practical application of the SEC in the variable-speed automobile exhaust systems. Three-fourths of the troughs of the SEC can be lifted by appropriate tuning of the extended inlet/outlet lengths. However, such mufflers suffer from high back pressure and generation of aerodynamic noise due to free shear layers at the area discontinuities. Therefore, a perforate bridge is made between the extended inlet and outlet. It is shown that the TL curve of a concentric tube resonator (CTR) can also be lifted in a similar way by proper tuning of the extended unperforated lengths. Differential lengths have to be used to correct the inlet/outlet lengths in order to account for the perforate inertance. The resonance peak frequencies calculated by means of the 1-D analysis are compared with those of the 3-D FEM, and appropriate differential lengths are calculated. It is shown how different geometric characteristics of the muffler and mean flow affect the differential lengths. A general correlation is obtained for the differential lengths by considering seven relevant geometric and environmental parameters in a comprehensive parametric study. The resulting expressions would help in design of extended-tube CTR for wide-band TL. (C) 2014 Institute of Noise Control Engineering.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to the INST NOISE CONTROL ENGINEERING, IOWA STATE UNIV, COLLEGE ENGINEERING, 212 MARSTON HALL, AMES, IA 50011-2152 USA
Department/Centre: Division of Mechanical Sciences > Mechanical Engineering
Date Deposited: 18 Jan 2015 06:40
Last Modified: 18 Jan 2015 06:40
URI: http://eprints.iisc.ac.in/id/eprint/50693

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