On the Role of Higher-Order Evanescent Modes in End-Offset Inlet and End-Centered Outlet Elliptical Flow-Reversal Chamber Mufflers

Mimani, A and Munjal, ML (2012) On the Role of Higher-Order Evanescent Modes in End-Offset Inlet and End-Centered Outlet Elliptical Flow-Reversal Chamber Mufflers. In: INTERNATIONAL JOURNAL OF ACOUSTICS AND VIBRATION, 17 (3). pp. 139-154.

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Abstract

This paper deals with the role of the higher-order evanescent modes generated at the area discontinuities in the acoustic attenuation characteristics of an elliptical end-chamber muffler with an end-offset inlet and end-centered outlet. It has been observed that with an increase in length, the muffler undergoes a transition from being acoustically short to acoustically long. Short end chambers and long end chambers are characterized by transverse plane waves and axial plane waves, respectively, in the low-frequency range. The nondimensional frequency limit k(0)(D-1/2) or k(0)R(0) as well as the chamber length to inlet/outlet pipe diameter ratio, i.e., L/d(0), up to which the muffler behaves like a short chamber and the corresponding limit beyond which the muffler is acoustically long are determined. The limits between which neither the transverse plane-wave model nor the conventional axial plane-wave model gives a satisfactory prediction have also been determined, the region being called the intermediate range. The end-correction expression for this muffler configuration in the acoustically long limit has been obtained using 3-D FEA carried on commercial software, covering most of the dimension range used in the design exercise. Development of a method of combining the transverse plane wave model with the axial plane wave model using the impedance Z] matrix is another noteworthy contribution of this work.

Item Type:	Journal Article
Publication:	INTERNATIONAL JOURNAL OF ACOUSTICS AND VIBRATION
Publisher:	INT INST ACOUSTICS & VIBRATION
Additional Information:	Copyright for this article belongs to the IIAV
Department/Centre:	Division of Mechanical Sciences > Mechanical Engineering
Date Deposited:	24 Jan 2013 05:15
Last Modified:	24 Jan 2013 05:15
URI:	http://eprints.iisc.ac.in/id/eprint/45285

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