@article {Ramya:2014:0736-2501:252,
title = "Improved tuning of the extended concentric tube resonator for wide-band transmission loss",
journal = "Noise Control Engineering Journal",
parent_itemid = "infobike://ince/ncej",
publishercode ="ince",
year = "2014",
volume = "62",
number = "4",
publication date ="2014-07-01T00:00:00",
pages = "252-263",
itemtype = "ARTICLE",
issn = "0736-2501",
url = "https://ince.publisher.ingentaconnect.com/content/ince/ncej/2014/00000062/00000004/art00008",
doi = "doi:10.3397/1/376225",
keyword = "34.2, 75.3",
author = "Ramya, E. and Munjal, M.L.",
abstract = "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.",
}