Determination of the nonlinear parameter by propagating and modeling finite amplitude plane waves

Abstract

The acoustic nonlinear parameter, B∕A, is an important piece of data whenever high intensity pressure fields are under consideration. In this work, an alternative method is proposed to measure this parameter. First, the method involves measuring the sound velocity and nonlinear waveform distortion of a finite amplitude plane wave propagating through a medium, Butanediol, whose density and attenuation law have been preliminarily determined. Measurements were performed in the nearfield of a piston where plane wave propagation regime exists. Impulse response of the hydrophone was determined and pressure waveforms were obtained by a convolution process. Then, the method involves modeling, in time domain and under experimental conditions, the theoretical nonlinear waveform distortion and fitting it to the experimental results by adjusting the B∕A parameter. Comparative measurements were performed using the technique of parametric interaction. The respective results for the two methods (B∕A=11.0±10% and 10.9±5%) are in a good agreement despite a smaller degree of accuracy for the proposed method.