Design Of Flame Colorimetric Temperature Measurement System Based On Image

Whether the flame temperature is normal or not is closely related to the safety and the cost of industrial production.Colorimetric temperature measurement is an effective means of flame temperature measurement,and the existing colorimetric thermometry has two shortcomings,one of them is to assume the flame as a gray body model,which is not realistic,the other one is the selection of CCD camera to capture images for processing,while the CCD’s R and G signals in the same temperature domain of unsaturated zone is a narrow range,resulting in a narrow temperature range.Aimed at the two problems of the colorimetric temperature measurement method,this thesis designed the flame temperature measurement system based on image colorimetric method,A flame emissivity model based on the radiation characteristics of carbon black was proposed,realized the dynamic adjustment of the flame temperature measurement range to improve the CCD temperature range narrow.The main research contents of this thesis are as follows:(1)Theoretical analysis of image colorimetric temperature measurement method.The flame temperature measurement system based on colorimetric method has been set up.Design suitable filter,imaging lens and CCD camera parameter combination according to demand.(2)The radiation characteristics of flame combustion products were analyzed:in the flame,the radiation of carbon black particles plays a major role,while carbon black particles do not conform to the gray body radiation,the emissivity formula of carbon black particles is introduced to establish an improved image colorimetric flame temperature measurement formula.The temperature field was iteratively solved by using Newton’s downhill method.And software structures used VS2010’s MFC programming to build a temperature measurement system of man-machine interface,realized the solution pretreatment,the temperature field of the flame image and output of the pseudo color map history data,dynamic adjust the exposure time,interesting region’s extraction and analysis,real-time rendering of single point temperature change curve function.(3)The luminance temperature has been determined and the dynamic adjustment of the range of temperature measurement has been studied.When the setting of parameters were unchanged,collected images at different temperatures of the blackbody furnace,polynomial fitting has been used to get R and G’s gray value and brightness temperature correspondence.After the high temperature image was attenuated by a certain factor,there must be a low temperature unreduced image’s R,G two-color gray value and high temperature image attenuation G two-color gray value equal,using this principle,we derive the formulas that map each other by changing the attenuation coefficient between different temperatures,and a black body furnace was used to verify the experiment,and the error was within 3%.(4)The flame of different kinds of fuel(alcohol,kerosene,shortening and candle)has been used to measure the temperature.The carbon content of these fuels increased gradually.When the combustion conditions are the same,the formation of carbon black is related to the carbon content of fuels.The S type thermocouple was used to compare the temperature measurement results,with the deviation of about 5%.