Active control of a centrifugal fan in a mock laptop enclosure

Active noise control (ANC) has shown promise in minimizing the effect of fan noise on users. Recent research by the authors has developed a model which is used to implement ANC on the inlets of centrifugal cooling fans. This model is based on minimizing radiated acoustic power in a model of the fan radiation and using those results to determine appropriate nearfield locations for the error sensor(s). Though this approach has been experimentally verified in an idealized setting, it was not verified in a more realistic situation. This paper describes how this model was expanded from its idealized setting to a mock laptop enclosure. When necessary modifications to the model were made, tonal noise can be predicted in the nearfield of the fan inlets, which allows one to develop an effective compact, realistic ANC setup for use in the mock laptop enclosure. With this ANC setup, significant global reduction of the inlet tonal noise can be achieved.