Experimental Investigation of Finite-Amplitude Acoustic Oscillations in a Closed Tube

This paper describes an experimental study of the pressure waveforms generated by a piston in a closed acoustic resonance tube. The study was prompted by waveform predictions of Chester [J. Fluid Mech. 18, 44–66 (1964)]. For the experimental system used, a high piston displacement amplitude is required to establish an experimental condition consistent with the approximations of Chester's analysis. Consequently, graphical comparisons between theory and experiment are made at resonance and at two frequencies bracketing resonance for three successively higher piston displacement amplitudes. Although better agreement is expected as the amplitude increases, this increasing agreement is observed only at the frequency above resonance, and not at resonance or below. However, good qualitative agreement between the shapes of experimental and predicted waveforms is found at high piston displacement amplitude. The pressure response curve of the experimental system is found to be asymmetric, i.e., skewed toward higher frequencies. On the basis of this observation, a qualitative argument is presented to account for the waveform inconsistencies between theory and experiment.