Abstract An appropriate concentration of micro/nano aluminum powder (MNAP) cloud is necessary for fuel air explosive (FAE) detonation. However, because of the fast dynamics, uncertainty interference, and transient characteristics of MNAP diffusion, experimental research on the measurement of MNAP cloud concentration is still lacking. Here, a pair of ultrasonic transducers were developed based on pulse drive, to measure the dynamic MNAP cloud concentration during MNAP diffusion in a standard 20-L explosion vessel. The measurement method was based on Lloyd-Berry ultrasonic attenuation theory. The experimental results showed that the ultrasonic pulse had a strong anti-interference ability, high precision, and real-time response to enable the characterization of MNAP diffusion concentration. The diffusion concentration gradients of MNAP were established and agreed well with the trend predicted by computational fluid dynamics simulations. The results also indicated that aluminum nanoparticles have better distribution characteristics than those of aluminum microparticles. These analyses provide technical support to improve FAE detonation energy.

中文翻译：

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微/纳米铝粉动态浓度测量

摘要 燃料空气炸药（FAE）爆炸需要适当浓度的微/纳米铝粉（MNAP）云。然而，由于 MNAP 扩散的快速动力学、不确定性干扰和瞬态特性，MNAP 云浓度测量的实验研究仍然缺乏。在这里，基于脉冲驱动开发了一对超声波换能器，用于测量标准 20 升爆炸容器中 MNAP 扩散过程中的动态 MNAP 云浓度。测量方法基于 Lloyd-Berry 超声衰减理论。实验结果表明，超声脉冲抗干扰能力强、精度高、响应实时，能够表征MNAP扩散浓度。建立了 MNAP 的扩散浓度梯度，并与计算流体动力学模拟预测的趋势非常吻合。结果还表明，铝纳米颗粒比铝微粒具有更好的分布特性。这些分析为提高 FAE 爆轰能量提供了技术支持。