Actuators positioning for multichannel active control system in circular ducts

Boudreau, Alex; L’Espérance, André; Bouchard, M.; Paillard, Bruno

doi:10.1016/s0003-682x(99)00034-1

Cited by 2 publications

(3 citation statements)

References 3 publications

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“…A squared error criterion is employed because using the minimisation of the non-squared error signal as the control object results in a very large negative error signal, which is undesirable. Accordingly, the cost function J, which attempts to minimise the error signal at error sensors, can be defined as (9) where E{ . } denotes an expected value.…”

Section: A Filtered-x Lms Algorithmmentioning

confidence: 99%

“…The upper control frequency was determined by the dimensions of the duct, which limits the maximum frequency value to that which can assure a onedimensional wave front transmission through the duct. 8 The location of the reference microphones, error microphones and control sources was determined on the basis of the results of many experiments realized in laboratory and guidelines presented in the literature, 9,10 in particular, the error microphones were placed in a position in which all natural frequencies were sufficiently excited for the algorithm to respond. The relative distance between reference sensor and secondary sources was fixed so, consequently, there were no group delay problems.…”

Section: Experimental Laboratory Setupmentioning

confidence: 99%

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Active control of low-frequency broadband air-conditioning duct noise

Egana¹,

Díaz²,

Viñolas³

2003

Noise Control Eng. J.

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The low-frequency broadband noise generated by an air-conditioning unit on a railway vehicle may be significant in situations where the vehicle is stopped or its speed is low. Low-frequency acoustic radiation is extremely difficult to attenuate using passive means, so in this work, active noise control (ANC) techniques were applied. Laboratory experiments were performed in which noise from two different sources, namely from loudspeakers and an axial fan, was introduced into a real air-conditioning duct, identical to that installed on a subway vehicle. The control approach used a doubled, single-input, single-output (SISO), feedforward, filtered-X LMS algorithm. Control algorithms were designed using the Matlab-Simulink program and the Real Time Windows Target toolbox of Matlab in order to run the ANC in real time. Attenuations of 15-20 dB at the error microphone locations were achieved when loudspeakers were used as primary noise generators. However, noise reduction was quite poor when noise was introduced via the axial fan. This was due to turbulence generated by the airflow, which has a negative influence on the performance of the control system. © 2003 Institute of Noise Control Engineering.

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Section: A Filtered-x Lms Algorithmmentioning

confidence: 99%

Section: Experimental Laboratory Setupmentioning

confidence: 99%

Active control of low-frequency broadband air-conditioning duct noise

Egana¹,

Díaz²,

Viñolas³

2003

Noise Control Eng. J.

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show abstract

“…It appears that researchers happen to use the duct that is available or more suited for the main objective of the research. For instance, Boudreau et al (2000) used round ducts, but their intent was to look at the non-uniform pressure distributions in round ducts and sample with microphone arrays then use multiple control channels to gain better ANC of pure tone noise. Many researchers have used rectangular ducts.…”

Section: Literature Reviewmentioning

confidence: 99%

Effects of diameter and cross-sectional partitioning on active noise control in round ducts

Slagley¹

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EFFECTS OF DIAMETER AND CROSS-SECTIONAL PARTITIONING ON ACTIVE NOISE CONTROL IN ROUND DUCTS by Jeremy M. Slagley Active noise control (ANC) is particularly useful in hard-walled ducts where plane waves propagate. Higher order mode waves are much more difficult to control. Basic acoustic principles dictate that the cut-on frequency at which higher order modes will first begin to eclipse simple plane waves in a duct will be determined by the cross-sectional diameter of the duct. The lowest frequency for higher order modes will increase as duct diameter decreases. Therefore, the range of frequencies where plane waves dominate will be greater and effective control using ANC better as duct diameter decreases. The result is that somewhat higher frequencies can be controlled with ANC for smaller diameters. To test those suppositions, a commercially-available ANC system was used to reduce random noise in round ducts having five different diameters. Results showed that insertion loss (IL) ranged from 5 to 30 dB in frequencies ranging from 40-1000 Hz, and varied inversely with size as expected. The same tests were conducted on a rectangular duct with one cross-sectional dimension fixed and one varied at seven different sizes. Results showed similar IL from 5 to 30 dB that varied inversely with size. If smaller diameters have broader frequency ranges that can be controlled with ANC, perhaps one could extend the frequency range for a large cross-section by partitioning it into smaller cross-sections. This hypothesis was tested by two methods of cross-sectional partitioning. Partitioning was achieved in one design by inserting a smaller duct inside a large duct. In a second design, a cross-shaped partition was inserted inside the large duct. ANC IL results were 1.7 to 2 dB better for the large duct partitioned by a smaller inner duct than the large duct alone (p=0.0146 for low frequency and p=0.0333 for high frequency). ANC insertion loss was 5.8 dB better for the large duct partitioned by a cross-shaped splitter at high frequencies than the large duct alone (p=0.0003). However, the cross-shaped partition system was 5.6 dB less effective at low frequencies than the large duct ANC IL alone (p<0.0001). The designs were evaluated to determine the minimal system requirements to achieve a substantial increase in IL inside a large diameter duct iii DEDICATION The author wishes to dedicate this work to his father, Charles A. Slagley, Jr., who passed away after a short struggle with cancer on 16 Jan 2005. He was an educator and inspiration to many, selected as Illinois Secondary School Principal of the Year for 2003. This work is also dedicated to the author's fifth child, Rosemary Claire, who was born in August, 2004. She reminded us all of the joys of life in this valley of tears. Her "Buka" got to hold her before he died. iv ACKNOWLEDGMENTS The author wishes to acknowledge some of the many people and organizations who contributed to or facilitated the work herein. Firstly, I acknowledge my utter dependence on Almighty God. I am al...

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Actuators positioning for multichannel active control system in circular ducts

Cited by 2 publications

References 3 publications

Active control of low-frequency broadband air-conditioning duct noise

Active control of low-frequency broadband air-conditioning duct noise

Effects of diameter and cross-sectional partitioning on active noise control in round ducts

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