Research on the selection and layout of the cantilever sensor based on photoacoustic spectroscopy gas detection technology

Abstract

Gas detection has become an indispensable part of the power equipment maintenance. Because of many advantages, cantilever enhanced photoacoustic(PA) spectroscopy was studied by many researchers. In this paper, with the help of Finite Element Method (FEM) simulations with the commercial software COMSOL, we have analyzed the distribution of the sound pressure inside the gas cell, in addition, we have analyzed the relationship between the Young’s modulus and size of the cantilever beam and its deformation, the relationship between the cantilever size and its eigen-frequencies were also obtained. Besides, we have performed the experiment of the deformation measurement. The results show that: for the gas cell, when it works at the first order resonance frequency, the maximum value of the sound pressure appears at the geometric center. For the main resonance cavity, with its length and radius increase, the first order resonance frequency of the gas cell decreases. Under the condition of ideal linear sound source, as the length and radius of the main resonance cavity changes, in the frequency domain, the sound pressure response curve changes, the maximum sound pressure corresponds the PA cell with 85 mm in length and 2 mm in radius. For the cantilever beam, with the increase of the Young’s modulus, the deformation decreases. The deformation is proportional to the fourth power of the length, whereas it is inversely proportional to the width and inversely proportional to the third power of the thickness. However, the experimental results showed that there may be a deviation in the vibration measurements by the vibration meter. As for the first order eigen-frequency, it is negatively correlated with the length and positively correlated with the thickness, but independent of the width. With the increase of the distance between the sound source and the cantilever beam, the deformation decreases.