Active Helmholtz Resonator With Positive Real Impedance

The impedance of a passive noise control device is strictly positive real, if the device is installed in noise fields with weak mean flows. Passive noise control devices are, therefore, more reliable than active ones. Active control may be applied to a Helmholtz resonator to introduce electronic resonance. It will affect the impedance Z act of the resonator. A controller may be designed such that (a) Z act is small and resistive at some tunable frequencies; and (b) Re{Z act } ≥ 0 in the entire frequency range of interest. If criterion (a) is satisfied, the active resonator can suppress duct noise at tunable frequencies. It is difficult to design a controller to satisfy criterion (b) because parameters of the controller depend on acoustic parameters of the noise field. A new method is proposed here to design an active controller to meet both criteria simultaneously. The satisfaction of criterion (b) implies a positive real Z act and a robust active resonator with respect to parameter variation in the noise field. Experimental results are presented to verify the performance of the active resonator.

[1]  A. Kelkar,et al.  Modeling and Control of Acoustic Ducts , 2001 .

[2]  Ernest Otto Doebelin,et al.  Measurement Systems Application and Design , 1966 .

[3]  R. Clark,et al.  Noise reduction in a launch vehicle fairing using actively tuned loudspeakers. , 2003, The Journal of the Acoustical Society of America.

[4]  Ml Munjal,et al.  An analytical, one‐dimensional, standing‐wave model of a linear active noise control system in a duct , 1988 .

[5]  Clark J. Radcliffe,et al.  An Electronically Tunable Resonator for Noise Control , 2001 .

[6]  Dennis S. Bernstein,et al.  State Space Modeling of an Acoustic Duct With an End-Mounted Speaker , 1998 .

[7]  Robert J. Bernhard,et al.  Adaptive-passive noise control with self-tuning Helmholtz resonators , 1997 .

[8]  Daniel L. Sutliff,et al.  ACTIVE RESONATORS FOR CONTROL OF MULTIPLE SPINNING MODES IN AN AXIAL FLOW FAN INLET , 1999 .

[9]  Fei Liu,et al.  A tunable electromechanical Helmholtz resonator , 2007 .

[10]  Y. Okamoto,et al.  Active noise control in ducts via side‐branch resonators , 1994 .

[11]  G. Koopmann,et al.  The use of resonators to silence centrifugal blowers , 1982 .

[12]  Dan Budny,et al.  Active noise control using damped resonant filters , 2003 .

[13]  Kosuke Nagaya,et al.  Silencer consisting of two-stage Helmholtz resonator with auto-tuning control , 2001 .

[14]  Kevin M. Farinholt,et al.  Acoustic Modeling and Control of Conical Enclosures , 2003 .

[15]  K. Uno Ingard,et al.  Notes on Sound Absorption Technology , 1994 .

[16]  R. Clark,et al.  Active damping of enclosed sound fields through direct rate feedback control , 1994 .

[17]  M. Utsumi.  Reduction of Noise Transmission in a Duct by Termination Impedance Control of a Sidebranch Resonator , 2001 .