Gas explosion is a process involving complex hydrodynamics and chemical reactions.In order to investigate the interaction between the flame behavior and the dynamic overpressure resulting from the explosion of a premi...Gas explosion is a process involving complex hydrodynamics and chemical reactions.In order to investigate the interaction between the flame behavior and the dynamic overpressure resulting from the explosion of a premixed gasoline-air mixture in a confined space,a large eddy simulation(LES)strategy coupled with sub-grid combustion model has been implemented.The considered confined space consists of a long duct and four branches symmetrically distributed on both sides of the long duct.Comparisons between the simulated and experimental results have been considered with regard to the flame structure,flame speed and overpressure characteristics.It is shown that the explosion process can qualitatively be reproduced by the numerical simulation.Due to the branch structure,vortices are generated near the joint of the branch and long duct.Vortices rotate in opposite directions in the different branches.When the flame propagates into the branch,the flame front is influenced by the flow field structure and becomes more and more distorted.The overpressure displays a similar behavior in the two branches which have a different distance from the ignition point.It is finally shown that the overpressure change law can directly be put in relation with the shape of flame front.展开更多
In order to investigate detonation propagation and distribution problems of premixed CH_(4)+2O_(2)mixture around a concrete structure such as a refuge chamber,detonation experiments in one small size tube were conduct...In order to investigate detonation propagation and distribution problems of premixed CH_(4)+2O_(2)mixture around a concrete structure such as a refuge chamber,detonation experiments in one small size tube were conducted.A simulation method was developed to obtain the flow field load distribution in the coal mine lane and pressure load of each part for the refuge chamber.Firstly,a physical model of a full-size explosiontest lane was established,which included the refuge chamber.With the calculations of the exact initial detonation pressure,the propagation characteristics of CH_(4)+2O_(2) premixed mixture detonation in the lane was simulated.Simulation results of various parts from AUTODYN are recorded,and the shock wave arrival time and the pressure peak can be observed from the detonation pressure-time curve over the changing propagation distance.So curve differences in different locations cannot be ignored.Then by detonation experiments in the small size tube,detonation pressure-time curves and velocity were obtained.Finally the simulation waveform of variation curve agreed well with the experimental results,which validated the detonation simulation method.The difference between shockwaves of the two sensors confirmed that detonation wave changed along with distance and time.These results should be taken into serious consideration for the detonation progration and distribution problem in future researches.展开更多
基金supported by the National Outstanding Youth Science Fund Project of National Natural Science Foundation of China[grant numbers 51704301]Foundation Strengthening Project of China[grant numbers 2019-JCJQ-JJ-024].
文摘Gas explosion is a process involving complex hydrodynamics and chemical reactions.In order to investigate the interaction between the flame behavior and the dynamic overpressure resulting from the explosion of a premixed gasoline-air mixture in a confined space,a large eddy simulation(LES)strategy coupled with sub-grid combustion model has been implemented.The considered confined space consists of a long duct and four branches symmetrically distributed on both sides of the long duct.Comparisons between the simulated and experimental results have been considered with regard to the flame structure,flame speed and overpressure characteristics.It is shown that the explosion process can qualitatively be reproduced by the numerical simulation.Due to the branch structure,vortices are generated near the joint of the branch and long duct.Vortices rotate in opposite directions in the different branches.When the flame propagates into the branch,the flame front is influenced by the flow field structure and becomes more and more distorted.The overpressure displays a similar behavior in the two branches which have a different distance from the ignition point.It is finally shown that the overpressure change law can directly be put in relation with the shape of flame front.
基金Supported by the National Science Foundation of China(E041003)the Fundamental Research Funds for the Central Universities(FRF-TP-15-105 A1)the Postdoctoral Science Foundation of China(2015M580049)
文摘In order to investigate detonation propagation and distribution problems of premixed CH_(4)+2O_(2)mixture around a concrete structure such as a refuge chamber,detonation experiments in one small size tube were conducted.A simulation method was developed to obtain the flow field load distribution in the coal mine lane and pressure load of each part for the refuge chamber.Firstly,a physical model of a full-size explosiontest lane was established,which included the refuge chamber.With the calculations of the exact initial detonation pressure,the propagation characteristics of CH_(4)+2O_(2) premixed mixture detonation in the lane was simulated.Simulation results of various parts from AUTODYN are recorded,and the shock wave arrival time and the pressure peak can be observed from the detonation pressure-time curve over the changing propagation distance.So curve differences in different locations cannot be ignored.Then by detonation experiments in the small size tube,detonation pressure-time curves and velocity were obtained.Finally the simulation waveform of variation curve agreed well with the experimental results,which validated the detonation simulation method.The difference between shockwaves of the two sensors confirmed that detonation wave changed along with distance and time.These results should be taken into serious consideration for the detonation progration and distribution problem in future researches.
