JSME International Journal Series B Fluids and Thermal Engineering
Online ISSN : 1347-5371
Print ISSN : 1340-8054
ISSN-L : 1340-8054
PAPERS
Experimental Investigation on Surface Impedance Effect of Sound Radiation from Low Mach Number Flow around a Circular Cylinder
Indika YAHATHUGODASadao AKISHITA
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2005 Volume 48 Issue 2 Pages 342-349

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Abstract

This paper describes a wind tunnel experiment on aero-acoustical effect of finite surface impedance on low Mach number (Ma) flow around a circular cylinder. Modification of surface acoustical properties of source area is said to result in reduction of radiated sound pressure level. In this paper the effect of the finite impedance not only to the acoustical effect but also to the hydrodynamic effects were examined. Three boundary conditions (BC) of surface impedance were supposed: 1) rigid surface, 2) uniform and 3) optimized impedance distribution by introducing an array of micro-scale perforation with a back space. A wind tunnel experiment was conducted according to the three types of BC with three different experimental models under the Reynolds number (Re) condition from 6000 to 12000. The third condition caused reduction of the far field pressure level by 6dB at largest case compared to the first condition.

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© 2005 by The Japan Society of Mechanical Engineers
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