论文部分内容阅读
声速是流体的一种基础热物理性质,定程干涉法是目前精度最高的气相声速测量方法之一。对于双原子及多原子气体,分子弛豫会对声速测量的精度产生影响。本文讨论了分子弛豫对气相声速测量的影响机理;基于量子化学方法,探索了气相工质的振动热容的计算方法,完善了分子弛豫影响的修正式,使得其修正不依赖于弛豫时间或者振动特征温度数据;以CO_2为例进行了气相声速实验数据的修正。结果表明:CO_2的修正结果具有较好的精度;定温下,分子弛豫的影响随压力减小而增大。
Sound velocity is one of the basic thermophysical properties of fluid. The method of fixed-range interferometry is one of the most accurate gas-phase velocity measurement methods currently available. For diatomic and polyatomic gases, molecular relaxation affects the accuracy of the sound velocity measurement. In this paper, the mechanism of molecular relaxation on gas-phase velocity measurement is discussed. Based on the quantum chemistry method, the calculation method of vibrational heat capacity of gas-phase working fluid is explored, and the correction formula of molecular relaxation effect is improved, which makes the correction independent of relaxation Time or vibration characteristics of temperature data; CO_2 as an example of gas-phase velocity experimental data correction. The results show that the correction result of CO_2 has good accuracy. The effect of molecular relaxation increases with decreasing pressure at constant temperature.