爆炸压强在建筑物表面分布的数值模拟

应用显式动力有限元软件AUTODYN建立了建筑物外部爆炸波传播的数值分析模型,分析了建筑物表面爆炸压强的分布规律,为在建筑物的抗爆设计中确定爆炸荷载模型提供了理论依据。

爆炸荷载作用下平板网架结构破坏倒塌分析

主要研究4种不同柱布置形式的平板网架结构在受到室外爆炸荷载作用时的动态响应行为和破坏倒塌模式,并分别计算不同边柱作为爆炸荷载受力柱时的极限爆炸压强。采用Johnson-Cock修正模型模拟在爆炸荷载作用下低碳钢材料的本构关系,综合考虑钢材塑性强度强化、应变率效应、物理损伤等力学特性。利用有限元显式求解器和相应辅助子程序实现对平板网架结构在爆炸荷载作用下结构响应、破坏和倒塌过程的数值模拟。研究表明,柱布置方案对平板网架结构的抗爆能力影响明显,且不同边柱受爆条件下平板网架结构的抗爆性能存在差异。

低压状态下航空煤油的爆炸危险研究

以3~#航空煤油为研究对象,通过可燃气体/蒸气爆炸极限测试装置测定航空煤油蒸气的爆炸参数,研究低压条件对航空煤油蒸气爆炸极限和爆炸压强的影响。初始环境压力设置为90、70、50 k Pa,温度设置为90℃,其他因素相同。通过实验研究不同低压状态下航空煤油的最大爆炸压强与相应的航空煤油蒸气体积分数的变化,以及在相同低压状态下最大爆炸压强与体积分数和爆炸所需时间的关系。随着航空煤油蒸气体积分数的增加,产生的最大爆炸压强先增加后减小。在初始压强一定的情况下,爆炸所需时间越长,爆炸产生的最大压强越低。

Effect of roadway turnings on gas explosion propagation characteristics in coal mines

In order to reveal the effect of turnings on explosion propagation, experiments were performed in three different pipes （single bend, U-shaped pipe and Z-shaped pipe）. Flame and pressure transducers were used to track the velocity at the explosion front. When the pipes were filled with methane, the explosion strength was significantly enhanced due to the turbulence induced by increasing the number of turnings, while the flame speed （Sf） and peak overpressure （ΔPmax） increased dramatically. In addition, the strength of the explosion increased in violence as a function of the number of turnings. However, when the bend was without methane, the turnings weakened the strength of the explosion compared with the ordinary pipe, shown by the decrease in the values of ΔPmax and Sf. In addition, the propagation characteristics in a U-shaped pipe were similar to those in a Z-shaped pipe and the values of APmax and Sf were also close. The results show that the explosion propagation characteristics largely depend on gas distribution in the pipes and the number of turnings. The different directions of the turnings had no effect.

Mechanical Model of Domestic Gas Explosion Load

With the increase of domestic gas consumption in cities and towns in China,gas explo-sion accidents happened rather frequently,and many structures were damaged greatly.Rational physical design could protect structures from being destroyed,but the character of explosion load must be learned firstly by establishing a correct mechanical model to simulate vented gas explo-sions.The explosion process has been studied for many years towards the safety of chemical in-dustry equipments.The key problem of these studies was the equations usually involved some ad-justable parameters that must be evaluated by experimental data,and the procedure of calculation was extremely complicated,so the reliability of these studies was seriously limited.Based on these studies,a simple mathematical model was established in this paper by using energy conservation,mass conservation,gas state equation,adiabatic compression equation and gas venting equation.Explosion load must be estimated by considering the room layout; the rate of pressure rise was then corrected by using a turbulence factor,so the pressure-time curve could be obtained.By using this method,complicated calculation was avoided,while experimental and calculated results fitted fairly well.Some pressure-time curves in a typical rectangular room were calculated to inves-tigate the influences of different ignition locations,gas thickness,concentration,room size and venting area on the explosion pressure.The results indicated that: it was the most dangerous con-dition when being ignited in the geometry centre of the room; the greater the burning velocity,the worse the venting effect; the larger the venting pressure,the higher the peak pressure; the larger the venting area,the lower the peak pressure.

Experimental study and theoretical analysis on the effect of electric field on gas explosion and its propagation

The effect of the electric field with different intensity on explosion wave pressure and flame propagation velocity of gas explosion was experimentally studied, and the effect of electric field on gas explosion and its propagation was theoretically analyzed from heat transportation, mass transportation, and reaction process of gas explosion. The results show that the electric field can affect gas explosion by enhancing explosion intensity and explosion pressure, thus increasing flame velocity. The electric field can offer energy to the gas explosion reaction; the effect of the electric field on gas explosion increases with the increase of electric field intensity. The electric field can increase mass transfer action, heat transfer action, convection effects, diffusion coefficient, and the reaction system entropy, which make the turbulence of gas explosion in electric field increase; therefore, the electric field can improve flame combustion velocity and flame propagation velocity, release more energy, increase shock wave energy, and then promote the gas explosion and its propagation.