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The effects of aluminum particle size on aluminized propellant combustion.

机译：铝颗粒尺寸对铝化推进剂燃烧的影响。

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The goal of this thesis was to: test current ideas regarding the complex behavior of aluminized propellant combustion, extend understanding to conditions not previously clarified, and demonstrate the applicability of the results in the tailoring of propellant formulations to specific applicational needs. The study focused on ammonium perchlorate (AP), hydrocarbon binder, aluminum (Al) formulations. All formulations had 11% polybutadiene (PBAN) binder and 89% solids (i.e., 18% Al and 71% AP). The primary propellant formulations were Al and fine AP (fAP) particle sizes. The values of these variables were chosen according to current practical standards and ideas on how to tailor the Al behavior. Bimodal size distributions were used for AP and Al. For bimodal Al formulations, the coarse Al particle size was 30μm (nominal) and the fine Al particle size was 0.1μm (nominal), and for bimodal AP, the cAP particle size was 400μm (nominal) and the fAP particle size was either 82.5μm or 10μm (nominal). The effects of the Al particle size, Al c/f ratio, fAP particle size and the AP c/f ratio were examined for monomodal and bimodal aluminized propellants. This experimental investigation challenges conventional thinking with regards to the mechanisms involved with Al combustion and provides guidelines in formulating propellants with minimal losses in performance.; The results showed the existence of an intense aluminized burning region (ABR) very close to the propellant surface with ultra-fine Al (UFAl) and 3μm Al that encouraged heat feedback to the flame front and to the propellant surface in the form of radiation and conduction. The high burning rates observed with UFAl were part of a continuum of reducing the size of the Al particles, which also lead to the presence of a dense ABR close to the propellant surface. It was also shown that major modification to the burning rates could be achieved by moderate amounts of UFAl and/or significant reduction in the AP c/f ratio. A detailed investigation was carried out on the nature of the gas phase flame complex with the goal of identifying (mapping) where the gas phase temperature is high enough to melt the Al2O3. The results showed the amount and degree of modification to the burning rates was found to be dependent upon the ability to ignite the Al through leading edge flames (LEF) and/or the matrix flame.; The use of UFAl significantly reduced the total production of the Non-Smoke Combustion Residue (NSCR) and increased the Smoke Combustion Residue (SCR). This phenomenon was found to be very dependent on the Al c/f ratio, AP c/f ratio and fAP size. The amount of agglomeration was found to be dependent upon the Al c/f ratio and pressure to the extent that large agglomerations were eliminated from the collected NSCR. The UFAl was found to burn to submicron residuals and SCR, this suggested the UFAl agglomerated significantly. In addition, the presence of the ABR close to the propellant surface was thought to disrupt and alter the conventional burning of the 30μm Al. This disruption in the 30μm Al burning was thought to be significant and responsible for large reductions in the collected NSCR.; The results from the investigation demonstrated that manipulation of bimodal Al distribution could effectively tailor both burning rates and residual oxide production.
机译：本文的目的是：测试有关铝化推进剂燃烧的复杂行为的当前观点，将理解扩展到以前未阐明的条件，并证明该结果在根据特定应用需求量身定制推进剂配方时的适用性。该研究集中在高氯酸铵（AP），碳氢化合物粘合剂，铝（Al）配方上。所有制剂均具有11％的聚丁二烯（PBAN）粘合剂和89％的固体（即18％Al和71％AP）。主要的推进剂配方为Al和精细AP（fAP）粒径。这些变量的值是根据当前的实用标准和有关如何调整Al行为的想法选择的。双峰尺寸分布用于AP和Al。对于双峰Al配方，粗Al粒度为30μm（标称），细Al粒度为0.1μm（标称）;对于双峰AP，cAP粒度为400μm（标称），而fAP粒度为82.5 μm或10μm（标称值）。研究了单峰和双峰镀铝推进剂的Al粒径，Al c / f比，fAP粒径和AP c / f比的影响。该实验研究挑战了有关铝燃烧机理的常规思维，并为配制性能损失最小的推进剂提供了指导。结果表明，在极靠近推进剂表面的地方存在强烈的铝化燃烧区（ABR），其中包含超细Al（UFAl）和3μmAl，可促进热量以辐射和辐射的形式反馈至火焰前沿和推进剂表面。传导。用UFAl观察到的高燃烧速率是减少Al颗粒尺寸的连续过程的一部分，这也导致靠近推进剂表面存在致密的ABR。还显示通过适量的UFAl和/或AP c / f比的显着降低可以实现对燃烧速率的重大改变。对气相火焰络合物的性质进行了详细研究，目的是确定（映射）气相温度足以熔化Al 2 O 3 。结果表明，燃烧速率的改变量和改变程度取决于通过前缘火焰（LEF）和/或基体火焰点燃铝的能力。 UFAl的使用显着降低了无烟燃烧残渣（NSCR）的总产量，并增加了烟气燃烧残渣（SCR）。发现该现象非常取决于Al c / f比，AP c / f比和fAP尺寸。发现团聚的量取决于Al c / f比和压力，以至于从收集的NSCR中消除了大的团聚。发现UFAl燃烧至亚微米残留物和SCR，这表明UFAl显着聚集。此外，认为靠近推进剂表面的ABR的存在会破坏和改变30μmAl的常规燃烧。人们认为，在30μm的Al燃烧中产生这种破坏是很明显的，并导致NSCR的大量减少。调查结果表明，控制双峰Al分布可以有效地调整燃烧速率和残留氧化物的产生。

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