Global Active Control Of Tonal Noise From Small Axial Cooling Fans

An active noise control system has previously been developed for the reduction of tonal noise radiated by small axial cooling fans, such as those found in desktop computers. This system uses four small actuators surrounding the fan in a mock computer casing. Due to industry volume constraints, a smaller fan and speaker configuration is desirable. If the smaller configuration is able to maintain similar control performance, as well as cooling performance, it is anticipated that practical application of the control system could be widespread. The smaller control system employs a smaller fan running at a higher speed, generating greater output noise levels at higher frequency tones. Global attenuation of these levels is desired. Experimental results of the system will be presented. A comparison of the two systems, including overall global control performance, will be discussed.