中文摘要：

声速是目前可测量准确度最高的热物性之一，也是热力学基础研究和工程应用的重要基础参数。本文基于圆柱定程干涉法原理，建立了国内首套可测量至高压（6MPa）的精密声速测量系统，解决了高压气体声速测量的关键问题，极大拓展了国内已有实验系统的测量范围（1MPa），也是国际上首次将圆柱声学共鸣腔应用于1MPa以上而且测量不确定度达到0．01％的成功尝试。新建立的实验系统包括声学圆柱共鸣腔及耐高压压力舱、频率测量系统、温度测量系统、高压压力测量系统、高压进气及真空系统。实验测试结果显示，新系统的声速测量不确定度小于0．01％，可应用于温度从220K至440K，压力高达6MPa的气体声速测量。

英文摘要：

Speed of sound is one of the most important thermophysical properties that can be measured precisely;it is also the important basic parameter in thermodynamic basic study and engineering application. A new sound speed meas- urement system was built based on the cylindrical resonator method ,which is the first precision sound speed measure- ment system that can measure the sound speed at high pressure up to 6MPa. The system solves the sound speed meas- urement problem at high pressure, greatly expands the measurement range （ 1 MPa） of the existing experiment system in China, and it is also a successful attempt in the world that uses cylindrical acoustic resonator at a pressure above 1MPa and achieves the uncertainty of 0.01%. The new built system includes the cylindrical acoustic resonator,high pressure vessel ,frequency measurement system, temperature measurement system, pressure measurement system, gas filling sys- tem and vacuum system. Experiment results show that the system can be used to measure the speed of sound in gases at temperature from 220 K to 440 K and high pressure up to 6 MPa with an uncertainty less than 0.01%