共振光声光谱系统中椭球形光声池的理论分析  

Geometrical Optimization of Resonant Ellipsoidal Photoacoustic Cell in Photoacoustic Spectroscopy System

作　　者：王巧云[1] 尹翔宇 杨磊 邢凌宇 WANG Qiao-yun;YIN Xiang yu;YANG Lei;XING Ling-yu(College of Information Science and Engineering,Northeastern University,Shenyang 110819,China)

机构地区：[1]东北大学信息科学与工程学院,辽宁沈阳110819

出　　处：《光谱学与光谱分析》2020年第5期1351-1355,共5页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(11404054,61601104);河北省自然科学基金项目(F2017501052);中央高校基本科研业务费专项资金项目(N172304032)资助.

摘　　要：实时在线气体检测在石油化工、现代工业、环境、医学诊断、智能电网中变压器在线监测等领域具有非常重要的意义。光声光谱气体检测技术是一种基于光声效应的气体检测技术,由于其具有检测灵敏度高、选择性强、分辨率高、检测范围宽、可实时在线监测等优点,已被广泛用于痕量气体检测。在光声光谱系统中,光声池是最重要的组成部分,其性能的好坏对于系统检测灵敏度和分辨率有着直接的影响。近些年来,光声光谱气体检测系统主要采用标准圆柱形共振光声池,系统的检测灵敏度和分辨率主要由微音器决定。为了进一步提高光声光谱法对于痕量气体检测的灵敏度和分辨率,对光声池进行深入研究分析,提出一种高灵敏度的椭球形共振光声池。结合气体热动力学和声学理论,利用COMSOL软件中的热声学模块分别对椭球形光声池和传统的圆柱形光声池进行了有限元方法分析,建立了其声学特征模型,并且对光声池的共振频率,光声池谐振腔内的声压分布情况以及声压级大小等声学特性进行了仿真研究。模拟了椭球形光声池的共振频率和声压信号大小与光声池谐振腔长度和中心半径之间的关系,从而优化了光声池的尺寸结构,选取了长度为100 mm,中心半径为5 mm的椭球形光声池最优结构,与相同外部尺寸下的传统圆柱形光声池进行了对比分析。结果表明,椭球形光声池的共振频率为1340 Hz,处于共振状态时产生的声压信号达到了5.01×10^-5 Pa,声压级为11 dB,品质因数为70;圆柱形光声池共振频率为1650 Hz,共振状态下产生的声压信号大小为5.7×10^-6Pa,声压级为-13.9 dB,品质因数为66。对比可知,椭球形光声池的共振频率明显小于圆柱形光声池,且最大声压信号是同尺寸圆柱形共振光声池的8.78倍,声压级提高了24.9 dB。由此可知,设计的椭球形共振光声池体积小,声压信号大Real-time gas detection is of great significance in manyfields,such as petrochemical industry,modern industry,environment,medical diagnosis,transformers.Photoacoustic spectroscopy(PAS)gas detection technology is a gas detection technology based on the PA effect.It has been widely used in tracegas detection because of its high detection sensitivity,high selectivity,high resolution,wide detection range and real-time monitoring.The PA cell is the most important componentof the PAS system.And the sensitivity and resolution of the system are directly affected by PA cell.The standard cylindrical structure of the resonance the PA cell is a common choice,and the detection sensitivity and resolution of the system are mainly improved by the microphone.In this paper,a high-sensitivity ellipsoidal resonant photoacoustic cell is proposed for the first time.Combining with the theory of gas thermodynamics and acoustics,the finite element method of ellipsoidal photoacoustic cell and traditional cylindrical photoacoustic cell is analyzed by COMSOL software,its acoustic feature model is established.The acoustic characteristics of the photoacoustic cell,such as resonance frequency,the sound pressure distribution in the cavity of the photoacoustic cell,and the acoustic pressure level are simulated.The relationship between resonance frequency,sound pressure,the size of ellipsoidal,cylindrical photoacoustic cell and the length and center radius of the ellipsoidal photoacoustic cell is simulated.The optimal length and center radius ofthe ellipsoidal photoacoustic cell is 100 and 5 mm,respectively.Compared with a conventional cylindrical photoacoustic cell,the resonant frequency of the ellipsoidal photoacoustic cell is 1340 Hz and the cylindrical photoacoustic cell is 1650 Hz.The sound pressure signal generated in the resonance state is about 5.01×10^-5 Pa and the cylindrical photoacoustic cell is 5.7×10^-6 Pa.The sound pressure level is 11 dB and the cylindrical photoacoustic cell is-13.9 dB.The Q-factor is 70 and the cylindrical pho

关 键 词：光声光谱 椭球形 共振光声池 

分 类 号：O433.5[机械工程—光学工程]