CFD Numerical Simulation Of Deflagration Characteristics Of Combustible Cloud Based On Premixed Combustion Model

Vapor cloud explosion is one of the most dangerous accidents in petrochemical production.Due to the flammability,volatility and explosiveness of raw materials,intermediates and products,as well as the high temperature and high pressure of production environment and devices,the potential risk of explosion accidents is extremely high.At the same time,explosion will cause serious damage to the surrounding pipelines and tanks.Once the flammable gas leaks under high pressure,its volume will expand rapidly.Combustible gas mixtures(oil vapor clouds)can cause subsequent explosions after sparks,resulting in more serious secondary disasters.There are abundant studies on the mechanism of vapor cloud explosion damage at home and abroad.However,the research on the load model of gas cloud explosion on anti-explosion structure is not perfect.Different from the traditional TNT equivalent method or other equivalent model method,this paper adopts the method of combining experimental and computational fluid dynamics(CFD)numerical simulation to build the model.The flow field characteristics and shock wave parameters of open space gas cloud explosion are studied.Based on Realizable k-? turbulence model and premixed combustion model,a computational model of gas explosion flow field is established by using fluent software.The time history curves of overpressure at different positions are analyzed and compared with the factors of different gas cloud concentration,radius,ignition position and mode.The difference is compared with the experimental results in the literature.The results show that the law of overpressure propagation in the air is consistent with the energy equivalence.That is,with the distance from the center of the cloud increasing,the peak overpressure decreases approximately reciprocally,and the numerical deviation is acceptable.The gas cloud explosion overpressure is preliminarily proposed.The formula for calculating pressure relation can be used in the application of engineering.A series of experiments on explosive shock wave characteristics of premixed gases were carried out by means of a large-scale experimental loading system of combustible premixed gas explosion.The curves of explosive shock wave over-pressure-time history under different charging time and concentration were obtained.The experimental results were compared with the numerical simulation results.It is clear that the method can be used to simulate gas cloud explosion within the acceptable range of error.