Reduction of interaction tones from axial flow fans by non-uniform distribution of the stator vanes

• Published in: Journal of sound and vibration Vol. 38; no. 3; pp. 357 - 371
• Main Authors: Duncan, P.E., Dawson, B.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 08.02.1975
• ISSN: 0022-460X; 1095-8568
• DOI: 10.1016/S0022-460X(75)80052-6

A theoretical model is presented for investigating the acoustic radiation resulting from the fluctuating forces at a downstream stator row which has non-uniformly circumferentially spaced stator vanes. It is found that, under certain circumstances, judicious uneven distribution of the stator vanes can be of significant acoustic benefit for medium speed fans. However, the deviations from uniform spacing required are quite considerable, and in order to avoid the associated aerodynamic problems a technique for simulating the desired configuration while leaving the vanes sensibly distributed around the annulus is developed. Experimental results obtained from a modified production fan are presented, and there is a significant degree of agreement between the experimental results and the predictions of the theory. This indicates that the technique may be used with some confidence in the design of inherently quiet turbomachinery.