The ignition delay of aluminum particles can be profoundly influenced by the agglomeration and combustion characteristics of solid propellants. In this experimental study, the ignition of individual aluminum particles in nitrate ester plasticized polyether (NEPE) and hydroxyl‑terminated polybutadiene (HTPB) propellant atmospheres was examined using laser ignition tests and high-speed photography. Focus was directed at the effects of the atmospheric composition, pressure, and aluminum particle size (500, 800 and 1000 µm). It was observed that the non-homogeneous reaction heat generation and convective heat exchange rates during particle ignition could be increased by increasing the CO content or ambient temperature, resulting in a shorter ignition delay time. This explains why aluminum particles tended to burn more efficiently in nitrate ester plasticized polyether than in hydroxyl‑terminated polybutadiene. In addition, it was found that the ignition delay time decreased with increasing pressure and was inversely proportional to the particle size squared. An ignition model for aluminum particle ignition in a multi-component atmosphere was developed and validated to describe the temperature change and energy transfer during ignition. The calculated ignition delay times were found to be within 5% of the experimental values. The model also showed that increasing the ambient temperature was more effective than increasing the CO content at enhancing ignition, and that CO was more effective than O, which was itself more effective than HO. Overall, this study provides useful insight into the ignition characteristics of aluminum particles in different propellant environments. The results could be used to develop more effective propellant formulations, optimize combustion processes, and improve safety in the handling and use of aluminum-based propellants.

中文翻译：

---

各种推进剂环境中铝颗粒点火动力学的研究


铝颗粒的点火延迟会受到固体推进剂的团聚和燃烧特性的深刻影响。在这项实验研究中，使用激光点火测试和高速摄影检查了硝酸酯增塑聚醚（NEPE）和羟基封端聚丁二烯（HTPB）推进剂气氛中单个铝颗粒的点火情况。重点关注大气成分、压力和铝颗粒尺寸（500、800 和 1000 µm）的影响。研究发现，通过增加CO含量或环境温度，可以增加颗粒点火过程中的非均质反应产热和对流换热速率，从而缩短点火延迟时间。这解释了为什么铝颗粒在硝酸酯增塑聚醚中比在羟基封端聚丁二烯中燃烧效率更高。此外，还发现点火延迟时间随着压力的增加而减少，并且与颗粒尺寸的平方成反比。开发并验证了多组分气氛中铝颗粒点火的点火模型，以描述点火过程中的温度变化和能量传递。计算得出的点火延迟时间与实验值的误差在 5% 以内。该模型还表明，在增强点火方面，提高环境温度比增加 CO 含量更有效，并且 CO 比 O 更有效，而 O 本身又比 H2O 更有效。总的来说，这项研究为了解不同推进剂环境中铝颗粒的点火特性提供了有用的见解。 研究结果可用于开发更有效的推进剂配方、优化燃烧过程并提高铝基推进剂处理和使用的安全性。