Sound radiation from a flanged inclined duct

McAlpine, Alan, Daymond-King, Alex and Kempton, Andrew (2012) Sound radiation from a flanged inclined duct. Journal of the Acoustical Society of America, 132 (6), 3637-3646. (doi:10.1121/1.4764883).

Record type: Article

Abstract

A simple method to calculate sound radiation from a flanged inclined duct is presented. An inclined annular duct is terminated by a rigid vertical plane. The duct termination is representative of a scarfed exit. The concept of a scarfed duct has been examined in turbofan aero-engines as a means to, potentially, shield a portion of the radiated sound from being transmitted directly to the ground. The sound field inside the annular duct is expressed in terms of spinning modes. Exterior to the duct, the radiated sound field owing to each mode can be expressed in terms of its directivity pattern, which is found by evaluating an appropriate form of Rayleigh's integral. The asymmetry is shown to affect the amplitude of the principal lobe of the directivity pattern, and to alter the proportion of the sound power radiated up or down. The methodology detailed in this article provides a simple engineering approach to investigate the sound radiation for a three-dimensional problem.

Text

__soton.ac.uk_UDE_PersonalFiles_Users_amca_mydocuments_My Work Stuff_Papers (AMcA)_Duct Acoustics_Radiation flanged inclined duct_Author copy_JASMAN13263637_1.pdf - Version of Record

Restricted to Repository staff only

Request a copy