Active Control of Portable Generator Set Noise: Heuristic Versus Design
Chris R. Fuller, Professor, Vibration and Acoustics Laboratories, Virginia Tech, Blacksburg, VA 24061
Tuesday, October 6, 2009
Research and development in the area of active noise control (ANC) continues to present significant challenges. Two methods for designing and implementing active noise control approaches are compared. In the first heuristic approach, the noise sources are identified using various measurement techniques such as spectral analysis, a beam forming microphone array and intensity scanning. The design and layout of the ANC system is then based upon this physical knowledge. In the second design approach, the hemispherical complex radiation pressure from the machine is measured using a rotating microphone array. The active sources are modeled using higher order spherical source expansions of BEM descriptions of the active sources (e.g. small speakers in enclosures) and are used to predict far field control at the same points as the measuring microphone array. The predicted control field is then combined with the measured field and the optimal control signals are obtained using a feedfoward control paradigm. The optimal locations of the control sources are then obtained for selected regions on the machine using a genetic algorithm. Both techniques have been applied to a 3kW portable diesel generator set. The two designs obtained were then implemented on the generator set and the control performance for each method measured. The results obtained in terms of the attenuation performance and locations of the control sources are compared for the two methods. Audio demonstrations of the active control performance are presented. [Work supported by US Army Power Generation Branch, Ft. Belvoir, VA] This presentation is an updated version of a Keynote Presentation at ACTIVE 2009, Ottawa, Canada, August, 2009.
Prof. Chris R. Fuller finished his B.E. and Ph.D. at Adelaide University, Australia in 1974 and 1978 respectively. His Ph.D. topic concerned re-active attenuation of sound in ducts. He then spent three years at the ISVR, University of Southampton, England as a Research Fellow studying coupled vibrations in fluid-filled cylinders. After this Prof. Fuller moved to the U.S. where he worked at NASA Langley Research Center as an NRC Research Associate for two years studying control of aircraft inlet and interior noise. In 1983 he accepted a faculty position at Virginia Tech in Blacksburg, Virginia where he is presently the Roanoke Electric Steel Professor of Mechanical Engineering. Prof. Fuller is the Director of the Virginia Tech Vibration and Acoustics Laboratories (a VT University Center) and also has a faculty position with the Virginia Tech Carilion Medical School in Roanoke, Virginia as well as a Resident Faculty position at the National Institute of Aerospace in Hampton, Virginia. Prof. Fuller's current research interests are in advanced active composite materials for noise control, structural acoustics, active control of sound and vibration, adaptive structures and biomedical ultrasound imaging. Prof. Fuller has authored over one hundred and fifty papers in various major technical journals and holds over ten patents in active control, four of which are in commercial use. He is the pioneer of two major fields in acoustics and vibration: Active Structural Acoustic Control, and more recently, Heterogeneous Materials for Passive Sound and Vibration Control. He is a Fellow of the Acoustical Society of America and an Associate Fellow of the AIAA. Prof. Fuller has been a past member of the Board of Directors of the International Institute of Sound and Vibration and INCE USA. He is the lead author of the text Active Control of Vibration published by Academic Press and has received several awards for his work. Prof. Fuller has presented numerous short courses on active control of sound and vibration and regularly consults with industry in those areas.