Research On Temperature Measurement Method Base On Tunable Diode Laser Absorption Spectroscopy Technology

In combustion diagnostics,the measured parameters mainly include the gas concentration and the combustion temperature.For high-temperature combustion environment,the measurement and analysis of these two parameters has been a hot spot.Currently,laser spectroscopy is an advanced measurement technique that enables rapid,non-contact,multi-component simultaneous measurement of multiple parameters.In this paper,Tunable Diode Laser Absorption Spectroscopy?TDLAS?is used to study the temperature measurement in the combustion environment.The gas molecular absorption spectroscopy theory,temperature measurement methods,spectral line selection,design systems and experiments were studied.These studies provide strong support for the feasibility of TDLAS theory temperature measurement and engineering applications.On the aspect of temperature measurement theory,this paper describes the gas absorption line intensity and line type and other related theories.The detailed analysis of different methods of TDLAS temperature measurement,and gives the corresponding temperature calculation.The temperature measurement models of direct absorption and wavelength modulation are designed,and compare the difference between the two systems development and measurement performance,to determine the wavelength modulation method for temperature measurement.On the aspect of feature line extraction,this paper uses program software to extract spectral parameter data and designs a detailed absorption spectrum pair selection scheme.And select H₂ O molecules and CO₂ gas molecules corresponding spectral pairs by absorption linear simulation.Analyze the upper limit of temperature and sensitivity of the selected line pair by simulation.On the aspect of system construction and design,combining with the results of line pair selection and system analysis,this paper selects the suitable device models,and conduct parameter analysis and performance testing on the main instruments such as lasers and detectors.Through the modulation test experiment,select the appropriate modulation parameters.On the aspect of experiment demonstration,this paper designs the experiment of measuring the ambient temperature of flat-bladed furnace with water molecule as target molecule,and proposes to calculate the value of modulation coefficient in double-line temperature measurement algorithm by experimental calibration.By comparing with thermocouple temperature measurement results and summarizing and analyzing the uncertainty factors of temperature measurement process,the feasibility of TDLAS temperature measurement is verified.