布里渊散射法流体音速测量系统的改进

Sound speed is one of thermophysical property of fluid. In the measurement of sound speed, Brillouin scattering method is a superior technique for high-temperature and supercritical regions. However, it is less accurate compared to acoustic methods. In order to improve measuring accuracy, this paper analyzed the uncertainty sources in sound speed measurement based on the basic principle of the Brillouin scattering method, and modifications were made to the optical path design and detecting device of our existing experimental system, resulting in the uncertainty decreasing from 1.05% to 0.22% (k=2). The sound speed of n-dodecane were then measured and compared with literature data, of which the average relative deviation and maximum deviation were reduced to 0.22% and 0.36%, respectively, validating the accuracy and reliability of the improved experimental system.