Al和AP粒径对CL-20推进剂燃面团聚及凝相产物特性的影响

为了研究Al和AP粒径对CL-20推进剂燃面团聚及凝相产物特性的影响,通过铝颗粒团聚可视化拍摄结合凝相燃烧产物(CCPs)特性分析的方法,对CL-20高能推进剂中铝的团聚过程进行了拍摄,并收集了CCPs;统计了燃面处不同粒径团聚物的滞留时间,对CCPs进行了微观形貌观察、物相分析及粒度分布测量,分析了Al和AP粒径对CL-20推进剂团聚及CCPs特性的影响。结果表明,随着团聚物粒径的增大,燃面处团聚物的滞留时间逐渐增大;对于粒径分布在60～270μm之间的团聚物,其滞留时间在1～20ms; CCPs中主要存在Al_2O_3和Al两种物质,包括粒径约1μm的氧化铝烟尘颗粒和粒径大于100μm的团聚物颗粒;Al粒径的减小导致CCPs最大峰值粒度增大,1μm左右的粒子体积分数增大,团聚程度增大;AP粒径的减小导致CCPs最大峰值粒度减小,1μm左右的粒子体积分数减小,团聚程度减小。     

含Mg/Al合金CMDB推进剂的燃烧性能

用PDSC、SEM、EDS和XRD研究了含Mg/Al合金粉和Al粉CMDB的热分解特性、熄火表面和固体燃烧产物组成.探讨了Mg/Al合金对燃烧机理的影响,建立了燃烧物理模型.结果表明,用等质量的Mg/Al合金粉替代Al粉,可提高推进剂的燃速、凝聚相热分解的剧烈程度和Al的燃烧效率;同时推进剂压强指数降低、凝聚相热分解放热量减少且其熄火表面上存在大直径Al熔凝颗粒团的现象消失.     

含铝HMX-CMDB推进剂燃烧残渣特征分析

为进一步了解CMDB推进剂中含铝凝聚相燃烧产物的形成机制及影响因素,对Al/HMX-CMDB推进剂燃烧残渣的形貌、表面成分及粒径分布进行了研究;制备了具有不同HMX/Al质量比(30∶7、22∶15)及不同铝粉粒径(1～2、13、30μm)的4种推进剂样品。采用靶线法测定了推进剂样品在压强为2～18MPa范围内的燃速;在恒压燃烧室中收集了推进剂在1MPa下产生的凝聚相燃烧产物;利用扫描电子显微镜(SEM)和光学显微镜对残渣形貌进行了观测,利用X衍射射线能谱(EDS)对残渣表面成分进行分析,并对残渣粒径进行了统计。结果表明,在2～18MPa下,增加铝粉含量和降低铝粉粒径会使推进剂燃烧效率降低,使铝团聚难以充分燃烧而产生大量残渣;观察到6类粒径大于20μm的球形和不规则形状残渣颗粒,其表面主要由铝和氧化铝构成;对残渣粒径统计表明,使用粒径13μm铝粉并且在其质量分数为7%时产生的残渣粒径较小,而质量分数增至15%时会使残渣粒径增大。     

铝含量和含氟有机化合物对丁羟推进剂燃烧性能的影响

为进一步提高HTPB推进剂的能量并抑制铝粉在燃烧过程中的团聚,制备了铝粉质量分数为16%~22%的端羟基聚丁二烯(HTPB)推进剂,并分别加入含氟有机化合物(OF)作为铝燃烧促进剂,研究了铝含量和OF对HTPB推进剂燃烧性能的影响;使用氧弹量热仪测定了推进剂在氩气氛围下(3 MPa)的爆热;收集在3 MPa下推进剂燃烧的凝聚相产物,采用激光粒度仪、X射线光电子能谱仪(XPS)及X射线衍射仪(XRD)等分别对其进行粒度分布、元素和物相分析;通过线扫描摄像机和高压燃烧室系统测定推进剂的燃速;利用高速摄影系统观察推进剂燃面上熔铝粒子的团聚过程。结果表明,HTPB推进剂在铝粉质量分数为20%时实测爆热最大,含氟有机物OF的引入使得爆热有所下降;随着HTPB推进剂中铝含量的提高,燃面上熔铝粒子的团聚愈加严重,凝聚相燃烧产物的尺寸和残留铝含量均逐渐增加;加入含氟有机物OF能够促使-Al2O3和AlF3的生成,有效抑制铝颗粒在燃烧过程中的团聚,使凝聚相燃烧产物的尺寸和残留铝含量显著降低,当铝粉质量分数为20%时,OF的加入使得残留铝的生成率降低了50%;较低的铝含量和OF的添加有利于HTPB推进剂燃速的提高。     

含铝固体推进剂燃烧过程中铝粉团聚现象研究进展

介绍了固体推进剂中铝的凝聚相燃烧产物种类及收集方法;分析了铝粉在燃烧表面区域的团聚物演化过程;综述了氧化剂粒径、燃烧压强、铝粉粒径和推进剂燃速对铝团聚的影响,并总结了各因素的作用原理;介绍了抑制铝粉团聚的方法。建议进一步开展铝团聚机理研究,深入揭示推进剂燃烧凝聚相及气相环境对铝团聚行为的影响,构建基于推进剂燃烧物理过程的铝团聚仿真模型,掌握满足高能量要求的铝团聚抑制技术。附参考文献74篇。     

DB/AP系燃烧剂的设计与性能研究

设计了以双基(DB)推进剂、高氯酸铵(AP)为主要组分的燃烧剂,并加入金属可燃剂B、Mg、Al来调整燃烧剂的燃烧性能,采用全自动量热仪、数码摄像机、热电偶和TG-DSC测试了燃烧剂的燃烧热、燃速、火焰温度和热性能.结果表明,金属粉的加入可以提高燃烧剂的燃烧热、燃速和火焰温度,并可以改变其火焰结构;对于长距离、高沸点物质的引燃,3种金属粉中B粉的效果最佳,DB/AP/B的火焰温度可达1 070℃,火焰长度达25cm,其燃烧过程也更稳定,而DB/AP/Mg和DB/AP/Al在燃烧过程中产生大量的火星;AP和金属粉对DB推进剂的热分解没有影响.     

高氯酸铵对铝/冰燃料燃烧特性的影响

通过点火燃烧实验研究了高氯酸铵添加量对铝/冰燃料点火燃烧特性的影响.结果表明,添加高氯酸铵可促进铝/冰燃料燃烧,明显减短燃料表面引燃时间,提高燃烧最大升温速率,明显降低最快反应速率对应温度.但随高氯酸铵添加量增大,铝/冰燃料出现不稳定燃烧,升温过程中热量流失严重.未添加高氯酸铵的铝/冰燃料燃烧产物为Al_2O_3,主要呈球形颗粒,添加1%高氯酸铵的燃烧产物为Al_2O_3和nAl,主要呈絮状物,添加3%高氯酸铵的燃烧产物主要以球形颗粒并夹杂部分絮状物形式存在.     

DB/AP系燃烧剂的设计与性能研究（英文）

设计了以双基(DB)推进剂、高氯酸铵(AP)为主要组分的燃烧剂,并加入金属可燃剂B、Mg、Al来调整燃烧剂的燃烧性能,采用全自动量热仪、数码摄像机、热电偶和TG-DSC测试了燃烧剂的燃烧热、燃速、火焰温度和热性能。结果表明,金属粉的加入可以提高燃烧剂的燃烧热、燃速和火焰温度,并可以改变其火焰结构;对于长距离、高沸点物质的引燃,3种金属粉中B粉的效果最佳,DB/AP/B的火焰温度可达1 070℃,火焰长度达25cm,其燃烧过程也更稳定,而DB/AP/Mg和DB/AP/Al在燃烧过程中产生大量的火星;AP和金属粉对DB推进剂的热分解没有影响。     

高氯酸铵(AP)粒度对端羟基聚丁二烯(HTPB)推进剂燃烧特性的影响

本文研究了含铝粉的 HTPB 推进剂中 AP 粒度对推进剂燃烧速度和燃速压力指数的影响。结果表明:AP 粒度越小,推进剂燃烧速度就越高、燃速压力指数亦随之增加,并给出了相应的经验公式。本文应用 Summerfield 粒状扩散火焰模型对 AP 粒度与 HTPB 推进剂燃烧特性的关系进行了讨论。     

高氯酸铵(AP)粒度对端羟基聚丁二烯(HTPB)推进剂燃烧特性的影响

本文研究了含铝粉的HTPB推进剂中AP粒度对推进剂燃烧速度和燃速压力指数的影响。结果表明:AP粒度越小,推进剂燃烧速度就越高、燃速压力指数亦随之增加,并给出了相应的经验公式。本文应用Summerfield粒状扩散火焰模型对AP粒度与HTPB推进剂燃烧特性的关系进行了讨论。     

Agglomeration Characteristics of Aluminum Particles in AP/AN Composite Propellants

Most solid rockets are powered by ammonium perchlorate (AP) composite propellant including aluminum particles. As aluminized composite propellant burns, aluminum particles agglomerate as large as above 100 μm diameter on the burning surface, which in turn affects propellant combustion characteristics. The development of composite propellants has a long history. Many studies of aluminum particle combustion have been conducted. Optical observations indicate that aluminum particles form agglomerates on the burning surface of aluminized composite propellant. They ignite on leaving the burning surface. Because the temperature gradient in the reaction zone near a burning surface influences the burning rate of a composite propellant, details of aluminum particle agglomeration, agglomerate ignition, and their effects on the temperature gradient must be investigated. In our previous studies, we measured the aluminum particle agglomerate diameter by optical observation and collecting particles. We observed particles on the burning surface, the reaction zone, and the luminous flame zone of an ammonium perchlorate (AP)/ammonium nitrate (AN) composite propellant. We confirmed that agglomeration occurred in the reaction zone and that the agglomerate diameter decreased with increasing the burning rate. In this study, observing aluminum particles in the reaction zone near the burning surface, we investigated the relation between the agglomerates and the burning rate. A decreased burning rate and increased added amount of aluminum particles caused a larger agglomerate diameter. Defining the extent of the distributed aluminum particles before they agglomerate as an agglomerate range, we found that the agglomerate range was constant irrespective of the added amount of aluminum particles. Furthermore, the agglomerate diameter was ascertained from the density of the added amount of aluminum particles in the agglomerate range. We concluded from the heat balance around the burning surface that the product of the agglomerate range and the burning rate was nearly constant irrespective of the added amount of aluminum particles. Moreover, the reduced burning rate increased the agglomerate range.     

Flame-retardant properties and synergistic effect of ammonium polyphosphate/aluminum hydroxide/mica/silicone rubber composites

The flammability behaviors of ammonium polyphosphate/aluminum hydroxide/mica/silicone rubber (APP/Al[OH]₃/mica/SiR) ceramifying composites containing APP, Al[OH]₃, and mica are investigated by cone calorimeter test. The thermal degradation and the synergistic effect of APP/Al(OH)₃/mica/SiR composites are investigated by thermal gravimetric analysis, X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. APP/Al(OH)₃/mica/SiR composites with 25 wt% of APP, 20 wt% of Al(OH)₃, 25 wt% of mica, and 30 wt% SiR presents a much lower total heat release, the value of peak heat release rate (PHRR), the maximum average heat release rate, the longest time to ignition, and time to the PHRR (t_PHRR), compared with the flame-retardant properties from composites with filler of APP and mica or APP and Al(OH)₃ alone. The results indicate that there is an excellent synergism in APP, Al(OH)₃, and mica, which endows APP/Al(OH)₃/mica/SiR composites with both good flame retardancy and fire prevention. The study on the synergism effect between fire prevention and flame retardancy of APP/Al(OH)₃/mica/SiR composites indicates that compounds containing P-O-Al are formed due to the reaction between APP and Al(OH)₃ during combustion in the early stage and a coherent, dense, and sealed structure is formed due to the reaction in mica, phosphates, and the thermal decomposition products of SiR during combustion in the later stage.     

含AP包覆硼的富燃推进剂燃烧机理研究

通过微热电偶测温和火焰单幅照相技术测试了含硼富燃料推进剂燃烧波温度分布及燃烧火焰结构;用扫描电镜对熄火表面形貌进行了观察,并通过能谱仪进行局部元素分析;对DSC曲线进行积分,得到推进剂的凝相放热量;测量推进剂燃烧的爆热和低压燃速,获得了其低压燃烧特性和一次燃烧放热情况。结果表明,含AP包覆硼的推进剂燃烧更剧烈,推进剂的绝热火焰温度更高,AP包覆硼提高了含硼富燃料推进剂的凝相放热、爆热和低压燃速。初步确定了该类推进剂的燃烧过程,为建立含硼富燃料推进剂燃烧物理模型提供了依据。     

The influence of aluminium oxide trihydrate particle size on the combustion of polydimethylsiloxane

The regularities of thermal degradation of Al(OH)₃ powders and the compositions of polydimethylsiloxane and fire retardant with different particle sizes (from 2 μm to 45 μm) were studied by the use of dynamic thermogravimetry (TG), mass spectrometry (MS) and high-temperature pyrolysis. It was shown that the size of the flame-retardant particles influences the physico-mechanical characteristics and combustion of polymeric compositions based on polydimethylsiloxane. The filling of polymer with fine flame retardants improves the tensile properties of vulcanizates but the flame retardance is reduced markedly. The time of free combustion and the length of the burnt parts are increased, the oxygen index and time of ignition delay are decreased while the flame temperature near the surface of the burning sample rises.     

Reduction of agglomeration effect by aluminum trihydride in solid propellant combustion

Aluminum trihydride (AlH₃) has gained considerable attention as a substitute fuel for aluminum in solid propellants. In this study, we conducted a systematic investigation to evaluate the effects of AlH₃ content, ranging from 0 % to 18 %, on propellant ignition, combustion, and agglomeration. Experimental methods such as thermogravimetry−differential scanning calorimetry (TG-DSC), laser ignition, high-speed photography, and collecting condensed combustion products (CCPs) were employed. The results indicate that AlH₃ significantly promotes the high-temperature decomposition of ammonium perchlorate (AP). Meanwhile, the addition of cyclotetramethylene tetranitramine (HMX) in propellant does not affect the hydrogen release reaction of AlH₃. As the AlH₃ content increases from 0 % to 18 %, the spectral emission intensity of the propellants decreases, and the ignition delay time initially increases from 253 ms to 321 ms, and then decreases to 258 ms. Furthermore, the burning rate increases with increasing the AlH₃ content, while the pressure exponent is reduced from 0.551 to 0.460. The inclusion of AlH₃ in propellants significantly inhibits aluminum agglomeration near the burning surface. Additionally, as the AlH₃ content increases, the mean particle size D₄₃ of the CCPs decreases from 50.95 μm to 8.28 μm at 1 MPa. The agglomeration degree of aluminum is very weak at 7 MPa, especially when the AlH₃ content exceeds 9 %. The conclusions drawn from this study can serve as valuable guidance for optimizing propellant formulations.     

Investigation of aluminum particle combustion in the flame of solid rocket propellants

Aluminum is widely used in modern solid rocket propellants for many purposes, but mainly to increase the specific impulse by raising the flame temperature. Most of the aluminum present in the powder state in the propellant does not vaporize on the burning surface, tending later to agglomerate into large particles difficult to burn even in the flame. The aim of this work is to study the behavior of the aluminum particles on the burning surface and in the gaseous region of the propellant flame structure. Different diagnostic techniques have been used: SEM on the burning surface of extinguished samples, pictures taken during combustion by filtered still camera, and a newly developed laser diagnostic. By the use of an UV laser beam and a high-speed-shutter TV camera, the Al particles on the burning surface have been visualized. A suitable image processor to extract information from the frames has been adopted. Tests on an HTPB. 12/AP.68/Al.20 propellant in the pressure range 10–50 atm have been performed. Results show the reliability of the diagnostics used here and have contributed to a better characterization of the tested propellant.Published in Fizika Goreniya i Vzryva, Vol. 29, No. 3, pp. 115–119, May–June, 1993.     

Combustion Wave Structure of AP Composite Propellants

The combustion mechanism of ammonium perchlorate (AP) composite propellants were studied. The oxidizer-rich propellants tested were made with excess concentrations of AP particles. The pressure deflagration limit of propellant decreases with increasing the concentration of binder. The combustion wave consists of two reaction regions I and II: the region I is the zone of AP monopropellant flame and the region II is the zone of diffusion flame. The heat flux feedback from the gas phase to the burning surface increases as pressure increases, and the heat flux is responsible for the burning rate characteristics.     

铝–油酸/正庚烷基纳米浆体燃料液滴着火燃烧特性

采用液滴悬挂法研究了正庚烷液滴、油酸/正庚烷混合燃料液滴、含20wt%纳米铝粉的铝–油酸/正庚烷基纳米浆体燃料液滴在不同温度下(600~800℃)的着火燃烧特性。用高速摄像机观测液滴进入管式电阻炉后的着火燃烧过程,使用热电偶记录液滴周围的气相温度变化,同时通过对应的温度曲线计算液滴的着火延迟时间。结果表明,纳米铝粉和油酸的添加均能降低正庚烷液滴的着火延迟时间。随温度升高,正庚烷、油酸/正庚烷混合燃料、铝–油酸/正庚烷基纳米浆体燃料液滴的着火延迟时间显著降低,但变化趋势逐渐趋于平缓。铝–油酸/正庚烷基纳米浆体燃料液滴的着火延迟时间与环境温度满足阿累尼乌斯方程。与纯正庚烷、油酸/正庚烷混合液滴的燃烧过程相比,铝–油酸/正庚烷基浆体燃料液滴的燃烧过程有显著差异,其燃烧经历3个阶段：正庚烷稳定燃烧阶段、正庚烷微爆炸阶段和表面活性剂微爆炸阶段。铝–油酸/正庚烷基浆体燃料液滴燃烧时间延长,火焰熄灭后又复燃,且燃烧过程中发生剧烈的火焰形变和铝颗粒溅射现象,大部分铝以团聚体形式在第三阶段完成氧化还原反应。     

Combustion of Aluminum Particles near the Burning Surface in AP/AN Composite Propellants

Aluminum (Al) particles are commonly used in ammonium perchlorate (AP) composite propellants of solid rockets for increasing performance. When propellants including Al particles burn, Al particles easily agglomerate on the burning surface of the propellant. The diameters of agglomerated Al particles are greater than those of mixed particles. The combustion efficiency of the propellant decreases with increasing burning time of the agglomerated Al particles. Therefore, it is important to observe how the agglomerated Al particles burn on the burning surface of AP composite propellant. A lot of researchers have studied Al agglomerate characteristics. Previous studies clarified the relation between the agglomerated Al particle diameter and luminous flame diameter around Al particles near the burning surface. The shapes of luminous flames around agglomerated Al particles are spherical or elliptical. This study evaluates the shapes of the luminous flame around agglomerated Al particles at a constant diameter or a different diameter. When the proportion of the luminous flame diameter (D_f) to the diameter of agglomerated Al particles (D₀) is 1.54–1.71 at a constant D₀, the luminous flames are almost perfectly spherical. Otherwise, the luminous flames are elliptical at a constant D₀. Furthermore, when D_f/D₀ is close to the mean value, the luminous flame is more spherical than elliptical at different D₀. The evaporation rate and the burning rate of Al vapor are inversely proportional to D₀. The oxidation gas temperatures were changed and the activation energy of Al vapor was obtained as 39.2 kJ mol⁻¹.