Optimizing the performance of aerosol photoacoustic cells using a finite element model. Part 1: Method validation and application to single-resonator multipass cells
Optimizing the performance of aerosol photoacoustic cells using a finite element model. Part 1: Method validation and application to single-resonator multipass cells
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DOI：
10.1080/02786826.2019.1650161
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发表时间：
2019-08-29
影响因子：
5.2
通讯作者：
Langridge, Justin M.
中科院分区：
文献类型：
--
作者：
Cotterell, Michael, I;Ward, Gareth P.;Langridge, Justin M.
光声光谱技术是非接触和原位测量气溶胶光吸收系数的首选技术。对于大多数气溶胶光声（PA）检测器，关键过程是通过激发PA单元的压力本征模来放大由光吸收产生的声压波。据我们所知，没有建模的声学，灵敏度或信号背景比（SBR）已被执行的PA细胞通常应用于气溶胶吸收测量。在第1部分手稿中，我们开发了一个有限元方法（FEM）框架来模拟光声细胞的声学响应和SBR。此外，我们通过比较单谐振器PA单元的FEM预测与使用原型单谐振器单元的测量来验证此建模框架，该单元的几何形状可以容易地调整。事实上，单谐振器单元通常应用于气溶胶吸收测量。我们表明，我们的模型准确地预测了声学特性的趋势与细胞几何形状的变化。我们研究如何共同的几何特征，用于抑制检测的背景和噪声过程中，影响SBR的单谐振器PA细胞。这些特征包括使用多个声学缓冲体积和可调空气柱。本文中描述的FEM模型和测量提供了一个配套文件的基础，该文件报告了气溶胶研究中常用的双谐振器PA单元的声学特性和优化。
Photoacoustic spectroscopy is the technique-of-choice for non-contact and in situ measurements of light absorption coefficients for aerosols. For most aerosol photoacoustic (PA) detectors, a key process is the amplification of the acoustic pressure wave generated from light absorption through excitation of a pressure eigenmode of a PA cell. To our knowledge, no modeling of the acoustics, sensitivity or signal-to-background ratio (SBR) has been performed for the PA cells applied commonly to aerosol absorption measurements. In this Part 1 manuscript, we develop a finite element method (FEM) framework to simulate the acoustic response and SBR of photoacoustic cells. Furthermore, we validate this modeling framework by comparing FEM predictions of single-resonator PA cells with measurements using a prototype single-resonator cell, the geometry of which can be readily adjusted. Indeed, single-resonator cells are applied commonly to aerosol absorption measurements. We show that our model predicts accurately the trends in acoustic properties with changes to cell geometry. We investigate how common geometric features, used to suppress detection of background and noise processes, impact on the SBR of single-resonator PA cells. Such features include using multiple acoustic buffer volumes and tunable air columns. The FEM model and measurements described in this article provide the foundation of a companion paper that reports the acoustic properties and optimization of a two-resonator PA cell used commonly in aerosol research.