Research On The Ignition Mechanism And Critical Conditions Of Oil Vapor Under The Action Of Explosive Heat

Oil is an important fuel and an important strategic material for the country.Oil vapor,which are volatiles of oil,are highly unstable and are typical flammable and explosive hazards among hydrocarbons.The thermal strike of enemy ammunition is prone to fire and explosion,which seriously threatens the safety of oil vapor production and storage and transportation equipment and facilities.In view of this,this paper studies the explosive heat release model of explosive explosion,the characteristics of explosive explosion parameters,and the influencing factors of oil vapor ignition by the method of theoretical calculation combined with numerical simulation.critical condition.The main work and conclusions are as follows:1.The two heat release models of shock wave adiabatic compressed air and high temperature explosion fireball heat radiation after explosive explosion are calculated respectively by theoretical calculation method,including the calculation of shock wave overpressure peak,explosion high temperature fireball heat radiation flux and so on.The relationship between the radiative heat flow and the temperature field is coupled.The theoretical calculation results can be compared and verified with the numerical simulation results of the explosive parameter characteristics of explosives,which can be used as the initial conditions for the thermal ignition of oil vapor.2.The AUTODYN software is used to establish the model of TNT explosive explosion in the air domain,and the Euler method is used to analyze the parameter characteristics of the explosive explosion.The results show that the overpressure peak and temperature peak of the shock wave after the explosion of the TNT explosive are positively correlated with the charge amount.relationship,which is negatively correlated with the blast source distance.The temperature propagation trends of different equivalent TNT explosives after explosion are basically the same.When the detonation source distance is small,the shock wave overpressure peaks of different equivalents of TNT explosives are quite different.Unite.Using AUTODYN finite element numerical simulation software to calculate the temperature field of TNT explosive after explosion has certain limitations,only the temperature rise caused by shock wave adiabatic compressed air can be obtained.The Henrych formula and the shock wave adiabatic equation can respectively predict the overpressure peak value of the shock wave and the change of the temperature field after the explosive explosion.3.Use FLUENT software to establish the thermal ignition model of oil vapor in open space,adopt "Standard k-ε turbulence model + Finite-Rate combustion model",and take the temperature field and pressure field after explosive explosion as the initial conditions for different influencing factors.The law of explosion exothermic ignition was analyzed,and the following results were obtained: the three influencing factors of charge amount,explosion source distance and oil vapor concentration on the overall pressure change after oil vapor thermal ignition can be divided into "small pressure fluctuation-formation of negative pressureThe pressure surge reaches the overpressure peak-the formation of negative pressure" these four stages.There is a positive correlation between the charge amount and the overpressure peak value after oil vapor thermal ignition,but with the increase of the charge amount,its influence on the overpressure peak value gradually decreases.Increasing the distance from the detonation source or reducing the amount of charge can reduce the flame temperature and flame propagation speed after the oil vapor are ignited,and the flame shape changes slowly.In the later stage of flame propagation,the outer flame temperature of the flame decreases after the oil vapor is ignited under low oil vapor concentration.In the case of high oil vapor concentration,the flame temperature is relatively stable.When the amount of charge is increased,the distance from the explosion source is reduced,or the oil vapor concentration is about 1.7%,the overpressure peak value,pressure rise rate,explosion power index and flame propagation speed after the oil vapor hot ignition will increase,and it can be obtained under these conditions.Under high pressure,the reaction of explosives to detonate fuel gas is more intense,and the damage is also stronger.4.Establish a multi-factor influence simulation working condition.According to the thermal ignition of oil vapor,analyze the ignition mechanism and critical conditions of oil vapor by the explosion and release of explosives.It is obtained that the heating mechanism of oil vapor is mainly caused by the thermal radiation effect of the explosion fireball and the shock wave adiabatic compressed air.The temperature rise effect,and the ignition mechanism is mainly caused by the former.The critical temperature of oil vapor ignition is about 700 K.By fitting the TNT equivalent that can reach the critical ignition temperature of oil vapor at the corresponding explosion source distance,the critical condition of the oil vapor ignition charge and the explosion source distance under the action of the explosion heat of TNT explosive is obtained.The upper and lower explosion limits of oil vapor under the coupling action of temperature and pressure were fitted,and the critical condition of oil vapor concentration for oil vapor ignition under the action of TNT explosive heat was obtained.91.88%;the explosion limit of oil vapor increased by 285.5%.