Dispersion based reduced-order model identification and boundary impedance control in a weakly coupled impedance tube

Vered, Yoav, Gabai, R. and Bucher, Izhak (2020) Dispersion based reduced-order model identification and boundary impedance control in a weakly coupled impedance tube. Proceedings of Meetings on Acoustics, 39 (1), [045005]. (doi:10.1121/2.0001215).

Abstract

Impedance tubes are commonly employed for non-destructive measurement methods of the acoustic properties of materials. Most physical models neglect the elastic nature of the tube resulting in a single mode propagation up to the cut-off frequency and are thus unable to accurately predict the propagati patterns in the case of liquidfilled tubes. An understanding of the dispersion pattern in the latter case is crucial for the success of the acoustic properties estimation procedure. Furthermore, a model-based control can be implemented on the basis of the dispersion relation which is able to enhance the existing methods. This work presents a case study of an air-filled impedance tube. A novel, two-actuators phase-perturbations technique was developed to identify the tube dispersion curves and to compare to analytical models. The accurate identification of dispersion curves was utilized in a successful effort to formulate a reduced-order model used to control a single mode traveling wave’s ratio by employing a feedforward control algorithm. The success of the case study in the case of a weak acoustic coupling mechanism such as the air-filled impedance tube emphasizes the capabilities when considering a stronger acoustic coupling such as in the liquid-filled impedance tube.

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Contributors

Author: Yoav Vered

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