摘要:
为了探究包覆铝粉爆炸火焰发展演化规律与传播机理，本文采用溶剂蒸发法制备了壳-核结构硬脂酸包覆铝粉（SA@Al），应用改进的哈特曼管，实验研究了粉尘云浓度对5%、10%与15%包覆浓度SA@Al粉尘爆炸火焰传播特性的影响；同时应用CHEMKIN模拟分析其气相爆炸反应动力学特征，进而揭示SA@Al爆炸火焰传播机理。结果表明，随粉尘云浓度增大，5%、10%和15%包覆浓度SA@Al粉尘爆炸火焰饱满度与连续性均先增强后减弱，平均火焰传播速度均呈先增大后减小的趋势，当粉尘云浓度为500 g/m3时火焰传播速度均达到最大。相比而言，纯铝粉爆炸火焰传播速度在750 g/m3时达到最大，表明硬脂酸包覆层促进了铝粉爆炸火焰的传播。此外，各粉尘云浓度下，10%包覆浓度SA@Al爆炸火焰最剧烈，平均火焰传播速度最大。SA@Al爆炸火焰升温主要包括两个阶段，快速升温阶段R2、R11和R10的温度敏感性较高，缓慢升温阶段R5、R11的温度敏感性较高。粉尘云浓度对缓慢升温阶段温升速率影响显著，使得500 g/m3时SA@Al的爆炸平衡温度最高。硬脂酸包覆层的燃烧促进了铝核的氧化，使爆炸反应得以强化，但过高的粉尘云浓度会导致O自由基受限，在一定程度上削弱反应强度。
Abstract:
In order to investigate the coated aluminum powder explosion flame development and propagation mechanism, a shell and core structure of stearic acid coated aluminum powder(SA@Al) was prepared by solvent evaporation method; the improved Hartmann tube was applied to experimentally study the influence of dust cloud concentration on the explosion flame propagation characteristics of SA@Al dust with 5%, 10%, and 15% coating concentration, observing the flame propagation behavior through high-speed photography and calculate flame propagation speed; and the CHEMKIN-PRO software was applied to analyze the kinetic characteristics of gas-phase explosion reaction, thereby revealing the mechanism of SA@Al dust explosion flame propagation. The results indicated that with the increase of dust cloud concentration, the fullness and continuity of 5%, 10%, and 15% SA@Al dust explosion flames were enhanced firstly and then weakened, and the average flame propagation speed showed a trend of first increasing and then decreasing. The flame propagation speed reached its maximum when the dust cloud concentration was 500 g/m3. In comparison, the pure aluminum powder explosion flame propagation velocity reached a maximum at 750 g/m3, indicating that the stearic acid coating layer promotes the propagation of the aluminum powder explosion flame. In addition, under each dust cloud concentration, 10% coating concentration SA@Al explosion flame were the most intense, and the average flame propagation velocity was maximized. The temperature rise of the SA@Al explosion flame with different dust cloud concentrations mainly consisted of two stages: rapid heating stage and slow heating stage. The rapid heating stage had higher temperature sensitivity for R2, R11, and R10, while the slow heating stage had higher temperature sensitivity for R5 and R11. The dust cloud concentration has a significant effect on the rate of temperature rise in the slow heating stage, resulting in the highest explosion equilibrium temperature for SA@Al at 500 g/m3. The combustion of stearic acid coating promotes the oxidation of the aluminum core, which strengthens the explosion reaction, but high dust cloud concentration leads to the limitation of O radicals, which weakens the reaction intensity to some extent.
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