Acoustic propagation in 3-D, rectangular ducts with flexible walls

Abstract

This article is posted here with the permission of the publishers, INCE/USA. Personal use of the material is permitted,; however, permission to reprint or republish any part of this article must be obtained from the publisher.24th National Conference on Noise Control Engineering 2010 (Noise-Con 10) Held Jointly with the 159th Meeting of the Acoustical Society of America. Baltimore, MD, USA, 19-21 April, 2010. INCE Conference Proceedings, 3: 1960-1968, Apr 2010. New York, NY, USA.In this article some analytic expressions for acoustic propagation in 3-D ducts of rectangular cross-section and with flexible walls are explored. Consideration is first given to the propagation of sound in an unlined 3-D duct formed by three rigid walls and closed by a thin elastic plate. An exact closed form expression for the fluid-structure coupled waves is presented. The effect of incorporating internal structures, such as a porous lining, into the duct is also discussed. Such configurations are directly relevant to the heating, ventilation and airconditioning industry