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本文阐述了通过音频信号共振频率测量气体音速的原理。同时还分析了实际的球共鸣器的结构对共振频率的影响并给予了相应的修正。据此设计和制作了一套高精度的球共鸣器和低频音频信号测量装置，建立了一套球共鸣声学法测量气体音速的实验系统。本文实验中研究温度、压力、气体音速测量的不准确度分别为±14mK、±2.0kPa和±0.0037％。通过对制冷剂R22饱和蒸气压和氩气低压下音速的测量验证了本实验系统的稳定性和精确性。
This article describes the principle of measuring the speed of sound of a gas by the resonant frequency of the audio signal. At the same time, the influence of the structure of the actual ball resonator on the resonance frequency is also analyzed and the corresponding correction is given. Based on this, a set of high precision ball resonator and low frequency audio signal measuring device was designed and fabricated, and a set of experimental system of ball resonance acoustic method to measure the gas sonic velocity was established. The inaccuracy of temperature, pressure and gas velocity measurements in this experiment are ± 14mK, ± 2.0kPa and ± 0.0037%, respectively. The stability and accuracy of the experimental system were verified by measuring the saturated vapor pressure of refrigerant R22 and the sonic velocity under argon low pressure.