Research On Temperature Detection Of Premixed Flame Based On Free Radical Spectrum

Combustion flame temperature is an important parameter of combustion,which is related to combustion stability,safety,economy and environmental protection.The two-color method is simple and reliable,because there is no soot particles in the premixed gas combustion,it can not be used directly.Therefore,this paper studies the temperature measurement of premixed gas combustion flame based on the spectrum of C2*free radicals,analyzes the formation mechanism of soot particles and the relationship between C2*free radicals and soot particles,and theoretically proves that C2*free radicals can be used as the conditions of temperature particles.Methane/air and butane/air are used for combustion of two premixed gases respectively to verify the temperature measurement algorithm.The main work of this paper is as follows:Firstly,based on Planck’s law and Wayne’s formula,the formula of two-color thermometry is obtained,and the applicable conditions of the formula are analyzed.The soot particles are the main products that can emit blackbody radiation in the combustion flame of hydrocarbon fuel.The formation process of soot particles is analyzed and studied.The important substances that participate in the formation of soot particles before the initial nucleus of soot particles are explored to find the particles with blackbody radiation.The precursor of soot particles is polycyclic aromatic hydrocarbons.The analysis of the group composition and reaction of polycyclic aromatic hydrocarbons shows that C2*radical is an important way to generate polycyclic aromatic hydrocarbons,which lays a theoretical foundation for the measurement of premixed gas flame temperature by dichroism based on C2*radical spectrum.Secondly,the distribution,characteristics and reactions of different free radicals in the combustion flame were analyzed.And it is theoretically analyzed and proved that C2*radicals meet the qualification conditions of temperature indicating particles.Therefore,C2*radicals have the characteristics of temperature indicating particles.If C2*radicals spectrum is selected,the applicable conditions of dichroism method can be met,thus the temperature measurement of premixed gas combustion flame can be carried out.Finally,two kinds of premixed combustion test-bed of gas(methane,butane)are built,including burner,multi-point temperature inspection instrument and spectrum acquisition system.Based on the multi-point temperature inspection instrument,the temperature of the combustion flame is measured,and the thermocouple temperature is compensated for the heat loss and data processing,as the measured temperature of the combustion flame.Based on the spectrum acquisition system to obtain the spectrum information of combustion flame at the characteristic spectrum line of C2*radical,the combustion flame temperature is calculated by two-color method,and compared with the measured temperature of thermocouple.The results show that the two-color method based on C2*radical is effective to measure the premixed gas flame temperature.