CN-122016659-A - Photo-thermal acoustic coupling simulation optimization method and system based on photo-acoustic spectrum gas detection

CN122016659ACN 122016659 ACN122016659 ACN 122016659ACN-122016659-A

Abstract

The invention discloses a photo-thermal acoustic coupling simulation optimization method and system based on photo-acoustic spectrum gas detection, and relates to the technical field of trace gas detection. The method comprises the steps of designing a geometrical structure model of the photoacoustic cell, setting simulation environment parameters, carrying out multi-physical-field simulation on the coupling process of light, heat and sound based on composite modulation incident laser excitation to obtain a sound pressure waveform, carrying out correction processing and data analysis on the sound pressure waveform, carrying out reverse optimization on simulation model parameters after comparing the sound pressure waveform with preset judgment conditions, and carrying out analysis and evaluation on the simulation model parameters after the reverse optimization to obtain a simulation optimization scheme. The invention solves the problems of simplified physical process, incomplete energy transmission chain, larger calculation result and experimental deviation and the like in the existing photoacoustic simulation method.

Inventors

JIANG MINGSHUN
SHI KAIXIN
JIANG MINGFEI
Pan Xinzhe
ZHOU QINGYU

Assignees

山东大学

Dates

Publication Date: 20260512
Application Date: 20251229

Claims (10)

1. The photo-thermal acoustic coupling simulation optimization method based on photo-acoustic spectrum gas detection is characterized by comprising the following steps of: designing a geometrical structure model of the photoacoustic cell, and setting simulation environment parameters; performing multi-physical-field simulation on the light, heat and sound coupling process based on the composite modulation incident laser excitation to obtain sound pressure waveforms, wherein the electric field spatial distribution of the incident laser in the photoacoustic cell is solved, the volume heat source is calculated based on the electric field spatial distribution output by the electromagnetic field module, the time domain response solution of the temperature field is obtained, and the thermal expansion sound source is constructed based on the time domain response of the temperature field and the sound field response is solved; performing correction processing and data analysis on the sound pressure waveform, and performing reverse optimization on simulation model parameters after comparing the sound pressure waveform with preset judgment conditions; and analyzing and evaluating the simulation model parameters after the reverse optimization to obtain a simulation optimization scheme.
2. The photo-thermal acoustic coupling simulation optimization method based on photo-acoustic spectrum gas detection according to claim 1 is characterized in that designing a photo-acoustic cell geometric structure model comprises designing a resonant cavity structure, particularly setting cavity length and radius, designing a buffer cavity structure, particularly setting cavity length and radius, designing an optical window, particularly setting thickness, diameter and position of the window, setting material properties, giving material characteristics to each domain in the model, defining boundary conditions, and setting a sound pressure detection point probe inside the resonant cavity of the photo-acoustic cell.
3. The photo-thermal acoustic coupling simulation optimization method based on photo-acoustic spectrum gas detection according to claim 1, wherein the specific steps of solving the electric field spatial distribution of the incident laser in the photo-acoustic cell are as follows: obtaining incident laser after composite modulation, wherein a composite modulation mode combining sawtooth wave modulation and sine wave modulation is adopted; and calculating the electric field space distribution after the incidence of the composite modulation driving laser.
4. The photo-thermal acoustic coupling simulation optimization method based on photo-acoustic spectrum gas detection according to claim 1, wherein the specific steps of calculating the electric field spatial distribution after the incidence of the compound modulation driving laser are: Describing laser propagation by adopting a Gaussian beam to obtain an electric field vector; The spatial light intensity distribution is solved based on the electric field.
5. The photo-thermal acoustic coupling simulation optimization method based on photo-acoustic spectrum gas detection according to claim 1, wherein the specific steps of calculating a volumetric heat source and obtaining a time domain response solution of a temperature field based on electric field spatial distribution output by an electromagnetic field module are as follows: Calculating a volumetric heat source according to the electric field spatial distribution by using the beer lambert law; the temperature field time domain response is solved from the volumetric heat source based on the thermal conduction equation.
6. The photo-thermal acoustic coupling simulation optimization method based on photo-acoustic spectrum gas detection according to claim 1, wherein the specific steps of performing correction processing and data analysis on the acoustic pressure waveform and performing inverse optimization on simulation model parameters after comparing with preset judgment conditions are as follows: Preprocessing the sound pressure waveform; Processing the time domain signal by using a window function, and reducing spectrum leakage caused by sampling truncation; Performing fast Fourier transform on the windowed time domain signal, converting the time domain signal into a frequency domain signal, and calculating to obtain the amplitude and phase of each frequency component; Identifying a second harmonic component in the amplitude spectrum; Converting microphone noise to obtain a minimum sound pressure value limit; Threshold judgment is carried out on the second harmonic component according to the minimum sound pressure value limit, and corresponding control parameters are corrected according to the threshold judgment result; and establishing a concentration calibration model according to the calibration relation between the concentration and the 2f amplitude, and carrying out quantitative inversion of the gas concentration.
7. Photo-thermal acoustic coupling simulation optimization system based on photoacoustic spectrum gas detection is characterized by comprising: the parameter setting module is configured to design initial parameters of the photoacoustic cell and acquire incident laser; The optical-thermal-acoustic full-coupling simulation module is configured to simulate coupling processing of the incident laser based on optics, heat and acoustics according to the photoacoustic Chi Chushi parameters, wherein the electric field spatial distribution of the incident laser in the photoacoustic cell is solved, the volume heat source is calculated and the time domain response of a temperature field is obtained based on the electric field spatial distribution output by the electromagnetic field module, and the thermal expansion sound source is constructed and the sound field response is solved based on the time domain response of the temperature field; The data processing analysis reverse optimization parameter module is configured to perform correction processing and data analysis on the sound pressure waveform, and perform reverse optimization on simulation model parameters after comparing the sound pressure waveform with preset judgment conditions; And the performance and index evaluation and design optimization scheme output module is configured to analyze and evaluate the simulation model parameters after reverse optimization to obtain a simulation optimization scheme.
8. A computer program product, characterized in that the computer program product comprises a computer program which, when being executed by a processor, implements a photo-thermo-acoustic coupling simulation optimization method based on photo-acoustic spectral gas detection as claimed in any of claims 1-6.
9. A computer readable storage medium, characterized in that the computer readable storage medium stores a computer program adapted to be loaded by a processor and to perform a photo-thermo-acoustic coupling simulation optimization method based on photo acoustic spectral gas detection as claimed in any of claims 1-6.
10. A computer device, comprising: a processor adapted to execute a computer program; a computer readable storage medium having stored therein a computer program which, when executed by the processor, implements the photo-thermo-acoustic coupling simulation optimization method based on photo-acoustic spectral gas detection as claimed in any one of claims 1-6.

Description

Photo-thermal acoustic coupling simulation optimization method and system based on photo-acoustic spectrum gas detection Technical Field The invention relates to the technical field of trace gas detection, in particular to a photo-thermal acoustic coupling simulation optimization method and system based on photo-acoustic spectrum gas detection. Background The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art. Trace gases refer to component gases that are extremely low in concentration in air or other gas mixtures. Trace gas detection is practically applied in various fields nowadays, and can realize climate change evaluation by detecting greenhouse gas in real time in the fields of environmental monitoring and atmospheric science, and can realize real-time detection of gas leakage or not in the fields of industrial safety by analyzing fault diagnosis of decomposed gas in transformer oil and SF 6 decomposed gas detection scene in a high-voltage power system, thereby effectively ensuring production safety. At present, the detection of trace gas is mainly based on a laser spectrum method, which comprises an optical cavity ring-down spectroscopy (CRDS), a Tunable Diode Laser Absorption Spectroscopy (TDLAS), a photoacoustic spectroscopy (PAS) and the like. The photoacoustic spectroscopy technology has the advantages of high sensitivity and high selectivity, natural zero background characteristic, no requirement of an expensive high-reflection cavity mirror or an ultra-long optical path, compact system structure, easiness in miniaturization and the like, and is particularly suitable for high-precision online trace gas monitoring. The photoacoustic spectroscopy technology is an indirect absorption spectroscopy technology, and the basic principle is that gas absorbs modulated laser light, non-radiative relaxation generates periodic heating, and pressure waves (namely sound waves) with the same frequency as the light modulation are excited and detected by an acoustic sensor. Photoacoustic spectroscopy system PAS gas detection system is a complete instrument comprising a light source, a gas processing system (for controlling the gas concentration ratio in the laboratory stage), a photoacoustic cell and electronics for gas detection (microphone, lock-in amplifier, signal acquisition card and computer). The most critical component is the photoacoustic cell, which is an enclosed space isolated from the outside, all of which occur within the cell. Numerical simulation of photoacoustic cells is of great importance in photoacoustic spectroscopy research. Through simulation, the acoustic performance and the system response characteristic of the photoacoustic cell can be quantitatively evaluated before experiments, so that the working performance of the photoacoustic cell is analyzed, the structural design is optimized, and the experimental cost is remarkably reduced. The simulation research at present mainly focuses on three aspects of acoustic modal analysis, namely determining the main modal distribution and sound field enhancement position of a cavity by solving the characteristic frequency and modal morphology of a photoacoustic cell, providing theoretical basis for subsequent acoustic sensor arrangement and structural optimization, resonant frequency response analysis, namely carrying out frequency sweep under specific excitation to obtain a response curve of sound pressure amplitude along with frequency change, thereby determining the optimal working frequency and quality factor, and structural parameter optimization, namely researching the influence of geometrical parameters (such as cavity length, radius and the like) of the resonant cavity and a buffer cavity on the sound pressure amplitude and the resonant frequency by a system, and optimizing the structure to improve the intensity of a photoacoustic signal and the stability of the system. However, conventional simulation methods also have significant limitations. First, conventional models often consider only a single acoustic physical field, simulating the photoacoustic effect by directly applying a simplified periodic heat source or normal velocity excitation in the acoustic module. Although the method can qualitatively obtain the distribution of the resonant frequency and the sound pressure, the actual process of light field absorption and heat conduction cannot be reflected, so that the influence of key optical factors such as laser power, wavelength, light spot beam waist position and the like is ignored. Secondly, the result of the traditional acoustic simulation output is often dimensionless or relative sound pressure value, and the result can only be used for comparing the relative performances of different structures, but absolute sound pressure output with real physical significance cannot be obtained. Meanwhile, due to the lack of a driving term in the time di