Control of Axial Flow Fan Noise by Design

This paper discusses the present methods of controlling tonal noise in axial flow fans and puts forward some basic parameters for use in the design and selection of this product. Descriptions are given of the effects of fan casing geometry, the interaction of fixed duct elements and fan rotating parts, the effect of inlet disturbance and changes in noise level with radial clearance. Finally, guidelines are given for users of axial How fans in order to minimise noise levels.