Theoretical And Experimental Study On The Reconstruction Of Flame Temperature Field By TDLAS

The flame burning temperature is an important parameter to learn the flame burning state,with the environmental pollution caused by factory emissions increased,and our country makes efforts to strengthen the rectification,it is very important to obtain the flame combustion temperature to optimize the combustion process and reduce the discharge of pollutants.Tunable diode laser absorption spectroscopy?TDLAS?is a kind of measurement technology which has been paid close attention by many researchers in recent years because of its high selectivity,sensitive reaction,little interference,simple principle and convenient equipment,standing out of many other optical measurement technology.However,in terms of temperature measurement,TDLAS technology still has two important problems,during the measurement,the time and space can't be synchronized,and TDLAS measures the light of optical path integral average,which can cause the deviation of non-uniform temperature field measurement.We introduce a dual-wavelength coupling method to improve the shortcomings of existing measurement methods in this paper.Then based on this method,combining the spatial inversion algorithm,we extend the TDLAS temperature measurement from one-dimension to two-dimension,and through numerical simulation and experimental verification,we show the content and conclusions as follows:1.Introduce a dual wavelength coupling method into TDLAS measurement and combine the Fourier analysis to solve the problem of time and space can't be synchronized.Through the theoretical derivation,the formula of measuring the temperature by the dual wavelength coupling method is obtained.Select the spectral line of H₂O,we processed some numerical simulations and measured room temperature for experimental verification,with a measuring error about-1.33%.In the relatively uniform temperature environment provided by the tube furnace,we placed the thermocouple array with ten thermocouples,compared with the temperature measured by TDLAS,still selecting the spectral line of H₂O.Comparing the average of temperature distribution along the optical path measured by the thermocouples,we can see that the dual-wavelength coupling method has a certain degree of credibility on the temperature measurement,with a measuring error no more than-1.6%.2.Based on the dual wavelength coupling method,introducing the spatial inversion algorithm,we extend the TDLAS temperature measurement from one-dimension to two-dimension.Firstly,we simulated two kinds of temperature field models,axisymmetric temperature field and non-axisymmetric bimodal temperature field,according to the investigation and study.Secondly,three kinds of spatial inversion algorithms are introduced to simulate these two temperature field models.According to the simulation results and the comparison of the advantages and disadvantages of these algorithms,we can conclude that algebraic reconstruction technique?ART?is more suitable for popularizing in practical application.Then,the temperature field distribution of methane flame combustion,using the laminar diffusion burner as the experimental platform,was measured and calculated by ART algorithm,and the temperature field distribution of the methane cross section was obtained.