Numerical Simulation Of Gas Deflagration To Detonation In Pipeline With Obstacles

In the development and application of detonation engine,how to obtain stable detonation wave is one of the most important links.How to obtain detonation wave in small energy and short distance has become the focus of research.Compared with other initiation modes,the DDT process in the obstacle pipeline has the following advantages: the required ignition energy is small,the structure is relatively simple,but the distance of DDT is long,so it is difficult to apply to engineering practice.In order to shorten the DDT distance in the obstruction pipeline,the DDT process in the obstruction pipeline is defined firstly,and the relationship between the DDT distance and the factors such as the distance between the obstruction,gas initial pressure,ignition energy,jet ignition and two-point ignition is deeply studied.The research results have important reference value for how to shorten the DDT distance in the obstruction pipeline.The main contents of this paper are as follows:(1)Aiming at the ambiguity of flame acceleration mechanism in DDT process in obstacle pipeline,the flame acceleration process in obstacle pipeline is divided into laminar flame period,vortex-flame period,shock-flame period and detonation period.The flame acceleration mechanism in each period is explained.In order to further analyze the flame acceleration mechanism of DDT,the distance between obstacles is studied by numerical simulation.The results show that the DDT distance is the shortest when the barrier spacing is 1D,and the larger the initial gas pressure is,the shorter the DDT distance is.(2)The relationship between ignition energy and jet ignition mode and DDT distance is obtained by numerical simulation.The results show that with the increase of ignition energy,DDT distance decreases gradually.Jet ignition can effectively shorten DDT distance.The optimum size of jet generator is 20 mm,the optimum installation angle of jet generator is 90 degrees,and the optimum location of jet generator is 5mm from the closed end.Place.(3)Aiming at the influence of two-point ignition on DDT distance,numerical simulation is carried out.The results show that two-point ignition can effectively shorten the DDT distance,and the optimum two-point ignition distance is 25 mm;sequential ignition can not shorten the DDT distance.