Numerical Simulation Study On Unconfined Flammable Vapor Cloud Explosion

With the rapid development of modern chemical production enterprises,because of combustible gas leakage caused by frequent accidents of major accidents,combustible gas explosion often leads directly to major casualties and property losses,one of the i mportant reasons is the combustible gas Explosion mechanism and the law of the stud y is not sufficient,resulting in unexpected events,explosion and explosion suppression d evice failed to play a very good effect.So far,many scholars have conducted in-depth r esearch and explorations on the explosion of combustible gas.However,due to its explo sion risk and complexity,the study of explosion under different conditions is still the h ot and difficult point in this field.The rapid development of computers has provided m ore convenient conditions for the study of combustible gas cloud explosion,especially t he widespread application of CFD numerical simulation method.In this paper,the study is to fully understand the theoretical basis of combustible gas explosion,and learn from the relevant research results.Based on the governing equa tions of fluid mechanics,Realizablek-?model and Eddy-Dissipation combustion model,t he theoretical models of flammable vapor explosion was established.In this paper,the c oupled solve was adopted to simulate the three-dimensional model of acetylene-air,whi ch the radial is 0.5m.Taking the premixed gas which the mass fraction were 5.3%,10.4%,13.3% and 15.4% to get the over pressure distributions of vapor cloud with time and space.Comparing the max explosion pressure with experimental dates,the maximum deviation of calculation results are 13.79%.The result show that the maximum explosi on pressure occurs in the early cloud explosion,and decreasing quickly over the time.I n the short term,there is a periodic over pressure wave in the outward diffusion.In ad dition to,the explosion pressure is biggest when come to the most dangerous mass fra ction In the production industry,we should try to avoid the most dangerous gas concen tration reaching its dangerous mass fraction,and preventing the occurrence of accidents.Based on the established numerical model of flammable gas cloud explosion,furth er obstacles are placed in the open space,that is,under the obstacle inducement,the expl osion with great destructive force will occur.Therefore,Gas cloud explosion field,and pr ovide the theoretical basis and data support for the feasible explosion-proof and explos ion-proof scheme.Based on the numerical simulation of the acetylene-air explosion u nder the condition of built-in obstacle,the acceleration mechanism of the obstacle to the explosion overpressure,the effect of the obstacle on the deflagration intensity and the number of the obstacle to the explosion are analyzed.Overpressure.The results sho w that the time of reaching the peak overpressure is shortened obviously and the max imum explosion pressure is about 6 ~ 8 times of the obstacle,the maximum explosionpressure can reach 25.33 KPa,the obstacle Which can cause serious damage to the bui lding.When the obstacle is inside the gas cloud,the peak overpressure caused by the e xplosive gas cloud explosion increases with the distance between the obstacle and the ignition source;When the obstacle outside the flammable gas cloud,the peak overpres sure gradually reduced;combustible gas explosion overpressure and the number of obs tacles is proportional to,that is,with the increase in the number of obstacles,obstruction s of the shock wave impeded The greater the degree,the greater the degree of turbule nce,will have a greater explosive power.