Dispersion curves identification and traveling wave control in a weakly coupled impedance tube

Abstract

Impedance tubes are commonly used for non-destructive measurement method 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 propagation patterns in the case of liquid-filled tubes. An understating 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 control a single mode traveling wave 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.

A Review on the High Sound Pressure Level Acoustic Measurement in the Aerospace Field

“…In the experiment, sound pressure levels over 160 dB were generated with the ultrasonic transducer. the acoustic wave tube could be divided into air-filled wave tubes and liquid-filled wave tubes [43]. Compared with the reverberation chamber test method, a lower sound power can produce a higher sound pressure level in a smaller cross section for acoustic wave tube method.…”