Micro and Nano Scale Phenomena of Aluminum Agglomeration During Solid Propellant Combustion

Abstract

Combustion of aluminized solid propellants exhibits phenomena associated with accumulation, agglomeration, ignition, and combustion of micro and nano-size aluminum particles. In general, agglomeration is an undesirable phenomenon, as it turns small particles into relatively large agglomerates, each containing many original particles, resulting in long combustion times which may lead to incomplete reaction, reduced jet momentum, and enhanced slag formation which adds parasite mass and may damage the motor insulation. This article presents a physical mechanism explaining the agglomeration process, revealing that small particles tend to agglomerate more than large particles. In addition, it suggests ways to reduce agglomeration of the aluminum particles via nano-coatings generating reactive heating and promoting ignition.

Hot Bridge-Wire Ignition of Nanocomposite Aluminum Thermite Synthesized Using Sol-Gel-Derived Aerogel with Tailored Properties for Enhanced Reactivity and Reduced Sensitivity

“…The use of nano-aluminum in solid propellants has evinced the potential for enhancing combustion performance and reducing combustion times, thereby catalyzing improvements in jet momentum characteristics and mitigating slag formation propensities [14,15]. The synthesis of aluminum nanoparticles for fuel applications has been explored [16], underscoring their prospective integration into micro-electromechanical systems and as reactive nanomaterials across diverse application domains.…”

Effect of Metal Nanopowders on the Performance of Solid Rocket Propellants: A Review

“…The heat of explosion of composite propellant without nAl is 6045 J·g −1 , which is higher than that of the samples with nZr and nTi particles (5793 and 5821 J·g −1 ) but lower than that of the sample with nAl particles (6104 J·g −1 ). The mechanical sensitivity result reveals that the use of micro-sized powder leads to a decrease in the sensitivities of friction and impact for solid propellants, while the compositions with nano-sized particles show high friction sensitivity and impact sensitivity [ 94 , 95 ].…”

Nano-Sized and Mechanically Activated Composites: Perspectives for Enhanced Mass Burning Rate in Aluminized Solid Fuels for Hybrid Rocket Propulsion

“…Aluminum combustion under solid/hybrid rocket motor conditions implies the presence of condensed combustion products (CCPs) [75][76][77][78]. Condensed products feature different compositions, morphologies, and sizes, depending on their genesis conditions (i.e., solid propellant/fuel composition details and operating conditions).…”

“…A larger agglomerate particle size and mass fraction results in higher performance losses due to incomplete combustion and two-phase flow [17]. Experimental and numerical studies on the Al combustion in solid propellant formulations were discussed in References [75][76][77][78][79][80][81][82][83].…”