Experimental Study On Ethylene Diffuse Flame By Several Monochromatic Images Between 0.6-0.7 Microns

Combustion is the main means of human use of energy. Undoubtedly, with the development of technology, the importance of burning in various fields will be further enhanced. Therefore, deepen the research of combustion is an effective way to develop high-efficiency clean combustion technology. Although combustion for the improvement of living standards and social progress of mankind is of great significance, with the rapid development of economy of China, the situation of energy supply is becoming tighter and tighter, and the environmental pollution produced by burned fuel is becoming more and more serious.The soot produced by the incomplete burning of hydrocarbons is still one of the most difficult issues to resolve in the field of combustion. It is not only related to the effective use of hydrocarbon fuel, and also to the protection of the environment and human health.Soot studies include research on the theory, numerical simulation and experimental study. Of all, experimental study is the key. In this dissertation, the present situation of investigations about soot measurement, and visualization of physical properties in flame by flame image processing at home and abroad is analyzed in detail. Besides, the present situation of how to solve the inverse problem of radiative transfer equation is also discussed.For visualizing non-uniform absorbing, emitting, non-scattering, axisymmetric sooting flames, conventional two-color emission methods are no longer suitable. In this dissertation, a mathematics model basing on the mechanism of solving the inverse problem of radiative transfer and image processing technology, used to calculate the distributions of temperature and soot concentration in laminar ethylene flames from the monochromatic radiation intensity images captured by a flame image detector is put forward. Then, least squares method, regularization method and linear programming method are separately used to solve the inverse problem of radiative transfer equation. The results indicate that linear programming method is the best appropriate method compared with the other two methods for the region of axisymmetric flame where the radiative intensity is relative small. Finally, the experimental study on measurement of distributions of temperature and soot concentration is implemented. The results indicate that the greater soot concentration lies inside the higher flame temperature in both types of flame, both inside the flame front and outside the flame axis. It is shown that the distribution of the soot concentration is the result of competition between soot formation and soot oxidation. Soot formation is related to the location in the flame, while soot oxidation has relationship with the temperature of the flame. Therefore, the distribution of the soot concentration in the laminar flame is associated with the flame structure and the temperature of the flame.