高热壁油气热爆燃实验研究

设计了高热壁油气热爆燃实验系统,对地下受限空间油气混合物在高热壁条件下的热爆燃现象进行研究,获得了油气热爆燃过程中测点的温度和各成分体积分数变化历程,以及热起燃过程的时序照片。根据实验结果,讨论了油气混合物热爆燃的着火方式、着火条件及着火延滞期规律。结果表明,高热壁条件下,密闭坑道内的油气混合物的着火温度高于自燃点近80 K。高热壁周围极大的温度梯度是着火温度远高于自燃点的原因之一。热壁条件下油气混合物引燃过程分为缓慢氧化阶段、快速氧化段和着火段3个阶段。热壁着火的延迟期在实验条件下相当长,着火方式以热壁表面油气点燃为起点。

热壁条件下油汽热爆燃数值模拟研究

探讨了汽油-空气混合物受热起燃过程的详细化学反应机理,建立了基于化学动力学和热力学相结合的油汽热爆燃起燃过程统一的仿真模型;基于该模型,对在密闭坑道的油汽混合物受到热壁的加热作用而着火过程,采用PISO算法进行了数值模拟;数值模拟结果与笔者实验结果吻合较好;同时根据计算结果,对热壁条件下的油汽热爆燃的引燃过程和特征参数的变化规律进行了分析。研究结果表明,统一模型综合考虑了详细化学反应、边界条件、传热传质,能较好解决油汽热爆燃的起爆过程的数值模拟问题;热壁条件下油汽混合物引燃分为五个阶段,即：缓慢氧化阶段、快速氧化段、着火段、熄火段、熄灭段;快速氧化段和缓慢氧化段以汽油自燃点为分界;油汽的着火温度远高于汽油自燃点;各组分在化学反应中的不同阶段的特征和作用并不相同。

基于统一理论的油气热爆燃模型研究

主要目的是探索详细化学反应模型引入油气热爆燃的热力学模型中的方法。首先建立了油气热爆燃的详细化学模型,即基于化学位确定系统组分,根据油气热爆燃起爆的特点确定控制热着火的主要化学链,基于组分的Arrhenius速度公式和热力学参数之间的关系,确定组分的消耗和生成速度以及组分化学反应放热率。然后以低马赫数、可压缩方程作为流场控制方程组,耦合详细化学模型和辐射模型,建立了基于化学动力学和热力学统一的油气热着火起燃过程的数学模型,即统一模型。基于该模型,对绝热受限空间内油气连续接触温升热壁条件下的热着火过程进行了数值仿真研究,并把计算结果和SCRS系统、零维模型以及实验值进行对比分析,研究结果表明：统一理论模型综合考虑了详细化学反应、复杂边界条件、流体流动,能较好解决油气热着火起燃过程的数值模拟问题。

Effects of charge size on explosives thermal initiation critical temperature under constrained conditions

In order to study the relationship between charge size and thermal initiation critical temperature of explosive in defined conditions,cook-off test about JH explosive was carried out at a heating rate of 1 ℃/min using self-designed cook-off experiment setup based on thermostatic control technology.Numerical simulation was conducted to study the effects of different charge sizes on thermal initiation critical temperature of explosives with FLUENT software.Experiment results show that there is a thermal initiation critical temperature in cook-off bomb.Simulation results show that when the ratio of the length to diameter of explosives grains is a fixed value,the thermal initiation critical temperature of explosives decreases with the increase of the diameter of explosives grains.When the grains diameter of explosives increase up to a certain value,the influence of charge size on thermal initiation critical temperature tends to be weakened.Charge size has no influence on the ignition point of explosives.The ignition point is always in the center of the grain.

Mathematical Modeling of Peat Self-ignition at Ambient Temperature Oscillations

In the classical formulation, the problem of thermal explosion in a finite volume of the reacting material in the presence of harmonic oscillations of the ambient temperature has been solved. It is shown that in the oscillation periods, commensurate with the adiabatic induction period of thermal explosion, implement a kind of resonance which corresponding with average ambient temperature. At both high and very low frequencies oscillations at ambient temperature, their influence on the critical condition and on the induction period of thermal explosion is negligible. However, at low-frequencies influence of ambient temperature oscillations, even a relatively low amplitude, on critical condition and especially on induction period of thermal explosion, can be very strong.