Research On Two-dimensional Reconstruction Technology Of Temperature Field Based On Tunable Laser Absorption Spectrum

Temperature is an important evaluation index of the combustion process.The accurate measurement of the two-dimensional temperature distribution in the combustion flow field has certain application value and research significance in the in-depth study of combustion mechanism,optimization of burner control strategy and fault diagnosis.To this end,this paper takes a low-emission tower coaxial staged combustion chamber as the measurement object,and carries out simulation and experimental research around the practical application of laser absorption spectroscopy tomography in the field of two-dimensional temperature distribution measurement,aiming to achieve combustion The main research work carried out on the reconstruction of the two-dimensional temperature field at the exit of the chamber with high spatial resolution is as follows.First,the research on the mechanism of laser absorption spectroscopy tomography technology was carried out,combined with actual measurement requirements,the selection of spectral line and temperature measurement performance analysis were carried out,and various measurement systems and reconstruction algorithms were studied in depth.On this basis,a two-dimensional temperature field reconstruction numerical simulation was carried out,and an improved algebraic iterative algorithm was discussed,and the single-peak and double-peak temperature field simulation models were inversely reconstructed using this algorithm.The error analysis of the reconstructed temperature distribution results is carried out,and the noise resistance analysis is carried out by introducing different levels of uniform white noise.After that,the overall design of a two-dimensional field measurement system based on tunable laser absorption spectroscopy technology was completed.According to the results of spectral line selection,two lasers with center wavelengths of 1391 nm and 1468 nm were selected to build an integrated measurement host together with the laser control board,fiber splitter,industrial computer and other hardware.A set of host computer software was designed and developed to realize voltage output,multi-channel parallel data acquisition and spectral signal processing.At the same time,a 7×7 orthogonal optical path measurement tool was designed according to the actual size of the burner.Finally,on the basis of numerical simulation and system construction,an experimental study of two-dimensional temperature field reconstruction based on absorption spectroscopy technology is carried out.First,the reconstruction experiment of candle flame temperature distribution under steady-state conditions is used to verify the reliability of the measurement scheme and the system in practical applications,and the reconstruction results are compared with the temperature measurement values of the thermocouple.Afterwards,the measurement experiment was carried out for the coaxial staged combustion chamber,and the two-dimensional distribution diagram of the temperature at the outlet of the combustion chamber under typical working conditions was obtained,and the reasons for the measurement error were briefly analyzed.The reconstruction results preliminarily verify the applicability of the tunable laser absorption spectroscopy tomography technology in the field of measuring the temperature distribution of the combustion chamber outlet,and it has certain reference value for the subsequent real-time monitoring of the combustion chamber operation status and optimization of control strategies..