Numerical Simulation Of Explosion Characteristics Of Hydrogen-air Premixed Gas Clouds In Open Space

With the development of new energy industry in China,hydrogen energy,as a kind of efficient clean energy,has a good development prospect.However,the safety of hydrogen energy in use becomes a constraint for further application of hydrogen energy because of its dangerous characteristics of low explosion limit and high explosion energy.Therefore,the study of hydrogen explosion hazard characteristics in air is helpful to determine the explosion hazard consequences,and then take measures to control the consequences of hydrogen explosion accidents.In this paper,a numerical model of hydrogen-air gas cloud explosion in open space was established based on FLUENT fluid mechanics calculation software.LES model was used to simulate fluid turbulence,and partial premixed combustion model was used to simulate combustion process.After the model is established,the feasibility of numerical simulation of gas cloud explosion is verified by comparing with the data of previous gas cloud experiments.On this basis,the variation rules of flame propagation,explosion overpressure,explosion dynamic pressure and explosion impulse of gas cloud explosion under different equivalent ratio and gas cloud size are studied.The simulation results show that the horizontal expansion deformation of the gas cloud boundary is larger than the vertical expansion deformation due to the ground constraint,and this phenomenon becomes more obvious with the increase of the chemical equivalent ratio.The time when the explosion overpressure of the gas cloud reaches its peak is consistent with the time when the flame surface covers the boundary of the gas cloud.The gas cloud overpressure peak,dynamic pressure peak and impulse all increase with the increase of chemical equivalent ratio.And there is an optimal chemical equivalent ratio to make the propagation velocity of explosion flame and explosion shock wave reach the maximum value,which is 2.0 in this paper.The peak values of overpressure and dynamic pressure increase with the increase of cloud size,while the action time and impulse of overpressure and dynamic pressure increase with the increase of cloud size.By comparing the simulation results of overpressure of gas cloud explosion of different chemical equivalent ratios and different gas cloud sizes with TNT equivalent method,it can be seen that TNT equivalent method has a small deviation in the calculation of far field of gas cloud explosion,but a large deviation in the calculation of near field of explosion.Therefore,Compared with TNT equivalent method,the open space gas cloud explosion model established in this paper can better reflect the overpressure characteristics of gas explosion with different chemical equivalent ratios and different cloud sizes.In this paper,the explosion overpressure simulation results compared with TNO pluripotent models found that the development trend of gas cloud explosion pressure on,and puts forward according to the gas cloud on the basis of different equivalent ratio,gas cloud size determination by TNO pluripotent model method,overcome the TNO pluripotent model in the application level of defects is difficult to determine explosion.In addition,based on the overpressure criterion and the overpressure-dynamic pressure criterion,the explosion damage evaluation of the gas cloud explosion results with different equivalent ratios and different cloud sizes was carried out to determine the explosion damage radius.