Directivity pattern of flow-induced noise from a wall-mounted, finite length circular cylinder

Abstract

Sound emanating from a wall-mounted, finite length cylinder immersed in cross flow presents a significant engineering problem and is relevant to a range of applications including aircraft landing gear and automobile appendages. However, despite its frequent occurrence in industry, there exists little experimental data on the noise created by such objects. To characterise this type of flow-induced noise source, acoustic directivity measurements have been taken in an anechoic wind tunnel at the University of Adelaide for wall-mounted cylinders of circular cross section. The aspect ratio (the cylinder length to diameter ratio, L/D) and orientation of the cylinders were varied to determine the influence of these parameters on noise directivity. Furthermore, the results were compared with the radiation pattern of the two dimensional case as well as with a dipole source (of equivalent power) at the assumed origin. The experimental data give further insight into the characteristics of the sound generated from wall-mounted, finite length cylinders in cross flow.