Investigation Of Flame Acceleration Mechanism For Methane-Air Premixed Gas In Tube

The gas explosion is one of the most destructive disasters in our life and industry manufacture, which always lead to casualties and economic losses, especially for coal gas explosion and gas pipeline explosion. It's difficult for us to control the disaster case when the explosion takes place, therefore it's necessary to study the inner mechanism of flame accelerating and further to prevent the gas explosion accidents.The experimental system on premixed flame fine structure was built up on the basis of visual combustion tube, which was used to explore the microscopic characteristics and acceleration mechanism of premixed flame propagation by the use of theoretical analysis, experiments, numerical simulation.(1) High speed schlieren photography system was used to record the dynamic process of premixed flame propagation clearly, then, instantaneous flame propagation speed can be calculated; precise measurement system was used to probe the changes of over press and ion current etc, such as dynamic pressure sensors and ion probe, thus, the microscopic characteristics of premixed flame propagation can be analyzed.(2) Flame acceleration mechanism of premixed gas with different concentrations of methane has been studied in tube to explore the effects of different methane content on the flame propagation speed and the transition from laminar flame to turbulence; interaction between pressure shock wave and flame can cause the changes of flame structure, promote the production and development of turbulent flame and ultimately speed up the flame speed, as well as coupling between flow and flame.(3) Numerical simulation was used to discuss premixed flame acceleration characteristic in different tubes, the tubes have the same section and different lengths. The effects of tubes of different lengths on flame propagation speed and over press can be analyzed; the effect of flow temperature on flame propagation speed can be obtained.