Study On The Premixed Laminar Flame Characteristic Of Hydrocarbon Combustion

In recent years, the automobile output increase brings with energy and environment problems that are drawing more and more attentions. As oil price increase and global warming as well as other problems become more and more seriously, the automobile structure should be modified and fuel properties be improved to meet the requirements of energy and environment. Hydrocarbon fuels are used widely; however, whether from foreign or domestic, the basis research of the hydrocarbon fuels combustion is scanty. The paper studies the premixed laminar flame characteristic of several most common hydrocarbon fuels with optical measurement.Paper introduces several research methods of the internal combustion engine, focusing on the advantage and disadvantage of optical diagnostic test technology. Introduction of the principle and the establishment of the constant volume combustion bomb test system and the high speed camera system is presented, then it introduces the basic theory and relevant knowledge of the ignition and combustion.In order to study the premixed laminar flame characteristic of hydrocarbon, a constant volume combustion bomb test system was designed. A general introduction of principle, structure and specific characters about the experiment system which contained constant volume combustion bomb, mixture preparation system, heating system, ignition system, combustion pressure measurement system, high speed camera system and data acquisition system, was also presented.By analyzing the flame pictures and pressure profiles, the differences of ignition delay period, flame propagation velocity and Markstein length were studied. The results show that the stretched, unstretched flame propagation velocity and Markstein lengths of n-heptane increase with MTBE and ethanol blends, which increases their flame stability. At the samne time, with the same octane number, the stretched, outstretched flame propagation velocity and Markstein lengths of isooctane with n-heptane are higher than that of the gasoline, also do the flame stability. Based on the flame appearances, both of them are looked almost same at the initial period of burning. However, they are quite different with each other at the late periood, the gasoline flame belonging to the carbon particles burning, and the isooctane with n-heptane flame belonging to the fully premixed combustion.