Effect of helical cables on cylinder noise control

This paper presents a parametric study on the far-field noise control effect of a circular cylinder with helical cables wrapping along cylinder span, aiming at finding an optimal operation condition for this treatment. Experimental results reveal that the noise control efficiency of this treatment is highly dependent on the non-dimensional thread pitch and cable density. The noise control efficiency gradually increases with the non-dimensional thread pitch and cable density increasing when both values are smaller than critical values. Further increasing the values of the two parameters, the control efficiency cannot increase any more. By choosing the optimal parameters of helical cables, both tonal and broadband noise can be remarkably suppressed, and the overall sound pressure level can be reduced by as large as 17 dB. (C) 2017 Elsevier Ltd. All rights reserved.