| With the development of country and the change of energy strategy, now the structure of energy has important changes, in other word, natural gas and liquefied petroleum gas will play more important roles in our life and industry. Meanwhile, with the development of modern industrial countries, the widespread use of flammable gas, industrial safety problems are becoming increasingly prominent. Mine gas explosion and other accidents not only cause a lot of casualties, but also caused huge economic losses to the country. Therefore, studies of the flame propagation characteristics in the pipeline, especially the research process of change of flame structure, the effective control of the explosion to prevent the occurrences of disasters is important.In this paper, the premixed combustion and the standard k-? turbulence model is used,and the multistep is selected to be the mechanism chemical reaction model to simulate the methane?ethylene?propane/air mixture in the 2D flame propagation process, then discuss the propagation characteristics of premixed flames. The main work of this paper consists of 3parts;(1)Simulation of the burning of three kinds of mixture gas in smooth tube and the tube with obstacles, the premixed gas under same initial conditions: initial temperature is 300 K,initial pressure is 1 atm. Simulation results show that: the flame of ethylene is faster than flame of methane and propane, because laminar flame speed of ethylene is bigger than others.(2) Simulation of the burning process of methane-air mixture in a two-dimensional tube with fixed ratio(? = 1), fixed distance between two obstacles(S=D), and change blocking ratio(BR = 0.3, 0.5, 0.7) obstruction. Observe the difference between all the results of the simulations, then compare it with the results in the smooth pipe under the same conditions,analyze the acceleration mechanism of premixed flames. The simulation results showed that:obstacle can improve the speed of flame, in a certain range, a higher BR will product a higher flame speed.(3) Simulation of the burning process of methane-air mixture in a two-dimensional tube with fixed ratio(? = 1), fixed blocking ratio(BR=0.5) obstruction, and change distance between two obstacles(S=0.5D, 1D, 1.5D). Observe the difference between all the results of the simulations, then compare it with the results in the smooth pipe under the same conditions,analyze the acceleration mechanism of premixed flames. The simulation results showed that:obstacle can improve the speed of flame, in a certain range, a smaller distance between two obstacles will product a higher flame speed. |
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