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arXiv 1406.0926physics.flu-dyn
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空间不均匀性对稳定爆轰波近极限传播的影响

Effect of Spatial Heterogeneity on Near-Limit Propagation of a Stable Detonation

Jianling Li, Xiaocheng Mi, Andrew J. Higgins

摘要:

通过计算研究了在爆炸介质中引入空间不均匀性对爆炸传播速度的影响。所研究的爆炸系统是一个理想气体,具有单一的放热反应,由压力相关的反应速率($p^n$)控制,压力指数为$n = 3$。一个压力依赖的反应速率,而不是指数依赖的反应温度的阿克里尼乌斯动力学,使用,使爆轰波是稳定的均匀的情况下,可以模拟与简单的,分析技术,从而引入非均匀性的效果可以清楚地识别。炸药的二维板被一层惰性气体包围,惰性气体具有与炸药相同的热力学性质。通过在模拟初始化中密度的大幅度二维正弦波动将不均匀性引入到炸药中,同时保持恒定的压力。计算模拟初始化与ZND解决方案的理想CJ爆轰,爆轰被允许传播到炸药层。模拟结果表明,非均匀介质中的爆轰波具有复杂的激波相互作用的胞状结构。爆炸能够传播到一个显着更薄的炸药层,并可以表现出比相应的均匀情况下更大的速度。改变正弦波的波长的参数研究表明存在最佳尺寸的异质性,在该最佳尺寸处,有利的效果是最大的,对应于约为理想CJ爆震的半反应区长度的10至50倍的波长。随着波长减小到反应区长度的大小,行为恢复到均匀的情况。

英文摘要:

The effect of introducing a spatial heterogeneity into an explosive medium is studied computationally by examining the detonation velocity near the limit to propagation in a thin explosive layer. The explosive system studied is an ideal gas with a single exothermic reaction governed by a pressure-dependent reaction rate ($p^n$) with a pressure exponent of $n = 3$. A pressure-dependent reaction rate, rather than the exponential dependence of reaction on temperature of Arrhenius kinetics, is used so that the detonation wave is stable in the homogeneous case and can be modelled with simple, analytical techniques, and thus the effect of introducing heterogeneity can be clearly identified. The two-dimensional slab of explosive is bounded by a layer of inert gas with the same thermodynamic properties as the explosive. The heterogeneity is introduced into the explosive via a large-amplitude, two-dimensional sinusoidal ripple in density in the initialization of the simulation, while maintaining a constant pressure. The computational simulations are initialized with a ZND solution for the ideal CJ detonation, and the detonation is allowed to propagate into the explosive layer. The simulations show that the detonation in the heterogeneous media exhibits a cellular-like structure of complex shock interactions. The detonation is able to propagate into a significantly thinner layer of explosive and can exhibit a greater velocity than the corresponding homogeneous case. A parametric study of varying the wavelength of the sinusoid shows the existence of an optimal size of heterogeneity at which the favorable effect is the greatest corresponding to a wavelength that is approximately 10 to 50 times the half reaction zone length of the ideal CJ detonation. As the wavelength is decreased to the size of the reaction zone length, the behavior reverts back to the homogeneous case.

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