布里渊散射法流体音速测量系统的改进

Improvement of Fluid Sound Speed Measurement System Based on Brillouin Scattering Method

音速是流体的一项基本热物性。布里渊散射法对于高温及超临界流体的音速测量具有优势,但与声学法相比其测量精度较低。为提高测量精度,本文从布里渊散射法音速测量的基本原理入手,分析了测量不确定度的来源,并从光路设计和探测装置两方面对现有的实验系统进行了改进,将音速的测量不确定度由1.05%降低至0.22%(k=2)。测量了正十二烷的音速并与文献数据进行对比,结果显示两者的平均相对偏差为0.22%,最大偏差为0.36%,验证了改进后实验系统的准确性和可靠性。

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.