Sound power radiated from acoustically thick, fluid loaded, axisymmetric pipes excited by a central monopole. (9th June 2022)

• Record Type: Journal Article
• Authors: Williams, Paul; Kirby, Ray; Karimi, Mahmoud
• Is Part Of: Journal of sound and vibration. Volume 527(2022)
• Publication Date: 2022-06-09
• Subjects: Axisymmetric cylindrical duct -- Acoustically thick wall -- Semi analytical finite element method; Sound -- Periodicals; Vibration -- Periodicals; Son -- Périodiques; Vibration -- Périodiques; Sound; Vibration; Periodicals; Electronic journals; 620.205
• DOI: 10.1016/j.jsv.2022.116843
• Languages: English
• ISSNs: 0022-460X

Abstract

Abstract: The aim of this study is to determine how the breakout noise of infinite length cylindrical shells excited by a central internal point source differ between acoustically thin and thick walls. This will further our understanding of acoustic radiation from axisymmetric pipes with thick walls, whose breakout noise excited by an internal monopole has not been studied previously. To accomplish this, pipes filled with air and immersed in an external fluid are investigated. This is performed numerically using the semi analytical finite element method to generate predictions above the critical frequency of the duct. It is observed that the maxima in the breakout noise occur when a certain class of eigenmodes with sound energy lying predominantly in the structure veer away from those where the sound energy lies predominantly in the fluid. For lightly fluid loaded pipes with thin walls this veering and associated increase to breakout noise is observed at the ring frequency and above the critical frequency. However for thick walled pipes, no corresponding increase in breakout noise is observed at the critical frequency for a pipe immersed in air. Instead the increase in breakout noise is observed only at the ring frequency and above. However, if the pipe is immersed in water then the increase in breakout noise is observed to occur below the ring frequency. Highlights: The semi analytical finite element method is used to model infinite length pipes. The pipes are filled and immersed in air and excited acoustically. Breakout noise is predicted for acoustically thick cylindrical shells. Results are presented above the critical frequency.