An Experimental Study Of The Effect Of Vent On Explosion In A Small Length-to-diameter Ratio Chamber

Natural gas used in residential buildings continues to leak and meet the explosion conditions,an explosion can occur,causing harm to people’s personal safety and property safety.The usual main uses of windows in residential buildings are ventilation and lighting.When a natural gas explosion occurs,it is the main building component in the residential building that communicates with the outside world.At this time,the window is extremely important as a vent.Common windows in residential buildings can be roughly divided into squares and rectangles in shape,and there are differences in area and opening position.Therefore,it is of positive significance to carry out explosion research on square and rectangular vents under different conditions of vent area and opening position to determine the safe opening method of windows,and to reduce disasters in case of natural gas explosion in residential buildings.In this study,a natural gas explosion experiment platform with a size of 300mm×300mm×600mm and L/D=2 was independently designed.Through the system to change the shape of the vent,the vent area and the opening position,the main components of natural gas were studied The impact of methane explosion characteristics.The research shows that the evolution of the flame front structure,the position of the flame front and the flame propagation speed in the chamber are divided into the pre-opening stage and the post-opening stage by the opening of the vent.In the pre-opening stage,the initial flame burned and developed in the shape of a spherical flame that was not restricted by the wall surface,and then developed into a finger flame.The flame propagated at a large initial speed,tended to be gentle after oscillation,and the position of the flame front changed slowly with time;After opening,the flame first propagates in the shape of a finger flame,and then stretches and deforms until it propagates out of the chamber.The flame propagation speed first jumps to a larger speed and then decreases,then oscillates,and it increases significantly in the later stage of propagation.The position of the flame front gradually increases with time during this stage.Due to the effect of buoyancy,the methane-air premixed gas is unevenly distributed in the chamber and stratified,resulting in a significant difference in the structure of the pressure waveform near the upper and lower wall surfaces of the vent and the peak value of the overpressure when the explosion occurs.The explosion area and opening position have an influence on the evolution of the flame front structure in the square and rectangular vent chambers,the position of the flame front and the flame propagation speed,the structure of the explosion pressure waveform and the size of the overpressure peak,and the specific performance is different.When the vents are located in the upper,middle,and lower parts,the experimental conditions corresponding to the safer vent opening methods are Z-0.3S,C-0.1Z,and Z-0.3X.When the opening blocking ratio φ=0.1,0.3,0.5,0.7,0.9,the experimental conditions corresponding to the safer vent opening methods are: C-0.1Z,Z-0.3X,C-0.5Z,Z-0.7X,Z-0.9X.The research results of this paper have reference significance for reducing the losses caused by natural gas explosion by opening windows in residential buildings.