Session 1pEAa: Active and Passive Control of Fan Noise 1pEAa1. Active control of axial and centrifugal fan noise

Both axial and centrifugal fans are used to cool information technology (IT) equipment. These fans generate noise that can be annoying to their users, particularly the tonal noise that can be radiated. Work has focused on developing a method to attenuate the tonal noise associated with both of these types of fans. A compact system is used, whereby control sources are placed in close proximity to the fan. A genetic algorithm has been implemented to determine optimal source configurations. The attenuation associated with some configurations is found to be much more sensitive to error than others. For a given configuration, by using a relatively simple point source model it becomes possible to identify optimal near-field error sensor locations, which results in a compact noise control solution that provides significant global attenuation of the radiated tonal noise. This paper will review progress that has been made to apply this method to both axial and centrifugal fans. Experimental results confirm that it is feasible to achieve significant global control using this method.