Flame Temperature Distribution Diagnoses By Infrared-Rays Absorption Computed Tomography

Up to now, the main energy source of human being is the energy produced during the combustion process of mineral fuel, such as oil, coal. While such fuel is not a renewable energy source, it will be exhausted in the near future. It has been the research interest of many scientists to burn fuel clearly and have high efficiency at the same time. Especially under dual pressure of environmental protection and energy crisis, the above problem becomes more instant.During the combustion process, many physical and chemical parameters are changed. Of these parameters, temperature is one of the most important, not only it is the crucial factor if the bum can occur, but also it is one of the main factor decide the combustion efficiency. For combustion theory and its engineering application, understanding temperature change law in the combustion has significant scientific and practical value.There are many temperature measurement methods, no matter thermal couples method or laser diagnoses technology cannot gain flame temperature distribution. Now X梤ay Computed Tomography(CT) technology has been successfully used in clinical circumstance. Integrating medium infrared radiation absorption phenomena and CT technology, a two-dimensional temperature distribution diagnosis method is proposed, which is named as infrared radiation absorption CT technology. The technology, carried out in combustion process, may lead to breakthrough in thermal science.As the physical theoretical basis, fundamentals of gas infrared radiation and absorption > molecular spectrum are presented. Additionally, laws of flame infrared radiation and absorption are detailed introduced; the principle formula and practical calculation methods are deduced. As the mathematical basis, several methods to reconstruct image from projections and presented and compared. In order to use in the experimental system co designed by author, digital calculating algorithm suited for computer is detailed deduced sequentially. As a result, the temperature distribution measurement principle by infrared radiation absorption CT technology can be understood easily.In order to verify the validity and feasibility of temperature distribution measurement principle, an experimental bench using infrared radiation absorption CT technology has been established. Temperature distribution of pre-mixed steady plane flame and unsteady flame in a combustion bomb are measured on the bench. The experimental results accord well to theoretical analysis results and experimental results using other methods, which manifests the measurement accuracy is high. Therefore, the measurement principle is proved to be correct and practical to diagnose flame temperature. The system is also proved to be properly designed, can operate conveniently.Up to now, researchers have not well understood the quantitative accuracyanalysis of CT temperature distribution technology. For the first time, on the view of algorithm and experimental system, the author analyze all the factors influcing the diagnose accuracy. On the basis of these analyses, "window" and convolving function with the best accuracy are selected, at the same time, the formulas of errors are deduced. All the above provide theoretical basis for the optimization of experimental system.At last, the conclusions of the whole thesis are drawn, and it is put forward that the future research emphases on the infrared radiation absorption CT technology should focus on: instantly get the absorption projections are the crucial factor to utilize the technology industrially; on the basis of the hypothesis that the gas is ideal gas, species concentration of particular gas medium can be measured at the same time, which must be helpful to comprehend combustion essence; if laser source to replaces blackbody stove, for irradiant flame, interferometric projection can be attained, and its temperature distribution will known. Which widens the technology application field.