用于测量短路径长度气体声速的声学方法。

Acoustic method for measuring the sound speed of gases over small path lengths.

作者信息

Olfert J S, Checkel M D, Koch C R

机构信息

Department of Mechanical Engineering, University of Alberta, Edmonton, Canada.

出版信息

Rev Sci Instrum. 2007 May;78(5):054901. doi: 10.1063/1.2736406.

DOI:10.1063/1.2736406

PMID:17552851

Abstract

Acoustic "phase shift" methods have been used in the past to accurately measure the sound speed of gases. In this work, a phase shift method for measuring the sound speed of gases over small path lengths is presented. We have called this method the discrete acoustic wave and phase detection (DAWPD) method. Experimental results show that the DAWPD method gives accurate (+/-3.2 ms) and predictable measurements that closely match theory. The sources of uncertainty in the DAWPD method are examined and it is found that ultrasonic reflections and changes in the frequency ratio of the transducers (the ratio of driving frequency to resonant frequency) can be major sources of error. Experimentally, it is shown how these sources of uncertainty can be minimized.

摘要

过去，声学“相移”方法已被用于精确测量气体中的声速。在这项工作中，提出了一种用于在小路径长度上测量气体声速的相移方法。我们将此方法称为离散声波与相位检测（DAWPD）方法。实验结果表明，DAWPD方法给出的测量结果准确（±3.2 m/s）且可预测，与理论值非常吻合。研究了DAWPD方法中不确定度的来源，发现超声反射和换能器频率比（驱动频率与谐振频率之比）的变化可能是主要误差来源。通过实验展示了如何将这些不确定度来源降至最低。