RDX-CMDB推进剂燃速温度敏感系数的实验研究

为了揭示RDX-CMDB推进剂中各常见组分对其燃速温度敏感系数的影响规律,制备了一系列含RDX、铝粉及燃烧催化剂的CMDB推进剂样品。采用氮气靶线法测得其在2~14MPa下的燃速温度敏感系数(σp)。讨论了RDX含量、铝粉、燃烧催化剂对RDX-CMDB推进剂燃速温度敏感系数的影响。结果表明,提高工作压强、增加RDX含量、添加燃烧催化剂均有助于降低RDX-CMDB推进剂在一定初始条件下的燃速温度敏感系数。配方中引入铝粉后可降低中低压下RDX-CMDB推进剂的燃速温度敏感系数,且燃速温度敏感系数几乎不随压强变化而变化。选用含邻苯二甲酸铅和没食子酸铋锆作燃烧催化剂,均可在2~10MPa下降低RDX-CMDB推进剂的燃速压强指数,同时降低燃速温度敏感系数。     

固体推进剂燃速测试技术研究进展

综述了固体推进剂的静态燃速、动态燃速和特定环境下的燃烧测试技术的研究现状以及各种燃速测试方法的特点,分析认为固体推进剂燃速测试技术的总体发展规律是由静态燃速测试逐步发展到动态燃速测试,在动态燃速测试的基础上出现了旋转过载燃速测试技术和压强瞬变条件下的燃速测试技术。现有燃速测试技术还用于测试固体推进剂常用高能添加剂的燃烧性能。提出了固体推进剂燃烧性能测试技术的发展方向:高压(超高压)燃烧性能测试技术、超低压(真空)燃烧性能测试技术、低温微重力环境下的燃烧性能测试技术等。附参考文献55篇。     

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。     

丁羟推进剂高压燃速及其调控方法研究进展

从丁羟推进剂的燃烧波结构出发,分析了高低压下推进剂燃烧火焰结构和燃面结构的变化,并借助燃速表达式阐明气固两相的传热传质是影响燃速的重要因素。综述了HTPB、AP粒径分布、RDX和HMX粒径等对丁羟推进剂高压燃速的影响,总结了金属氧化物、二茂铁及其衍生物、纳米催化剂、碳材料及其复合物、复合燃速调节剂在燃烧性能调控方面的研究进展,并分析了高压下丁羟推进剂发生燃速突增的可能原因。最后指出今后应加强以下几方面研究：(1)研究配方对丁羟推进剂高压燃烧性能的影响,阐明燃速拐点压强的变化规律;(2)研究压强对丁羟推进剂中各个组分燃烧特性以及组分之间相互作用的影响;(3)开发新型燃速调节剂,实现对丁羟推进剂高压燃烧性能的有效调控。     

颗粒粘结高燃速推进剂燃速设计方法的研究

介绍了颗粒粘结高燃速固体推进剂的工艺特点,利用推进剂燃烧特征化学基团方法预估了几种小药粒和速燃粘结剂的燃速,提出了颗粒粘结高燃速固体推进剂燃速的设计方法.     

无铝低燃速NEPE推进剂的燃烧性能

采用水下声发射法测定了无铝低燃速NEPE推进剂的燃速,研究了增塑剂种类、高氯酸铵(AP)与奥克托今(HMX)含量、AP粒度级配以及降速剂对无铝NEPE推进剂燃烧性能的影响。结果表明,通过选择合适的增塑剂、调整AP/HMX的相对含量、AP粒度级配以及采用有效的降速剂可使推进剂基础配方在3.5MPa下静态燃速达到4.0~5.5mm/s,2~5MPa下静态压强指数可降至0.30以下;NEPE推进剂燃烧时,NO2的生成速度越慢或NO2的含量越低,则推进剂的燃速越小,反之则越高。     

超声波燃速测试技术在固体推进剂研制中的应用

介绍了通过连续测量超声脉冲在推进剂中的反射时间,确定推进剂燃烧端面的位移,从而得到推进剂燃速的测试方法。它可以设置不同的压强变量条件来进行连续的实时燃速测量。叙述了国外超声波燃速测试技术在推进剂稳态燃速特性、非稳态燃速特性以及各种发动机燃速特性研究领域中的应用。评述了超声波燃速测试方法的特点和适用性,并建议国内研究机构开展该项技术的研究工作。     

镁/铝合金水反应金属燃料推进剂的燃烧性能

通过高能球磨工艺制备了高活性球磨镁/铝合金粉,并制备了两组镁/铝基水反应金属燃料推进剂,用固体推进剂燃速测试系统测定了其燃速。采用氧弹量热仪测定了推进剂的爆热值,并收集推进剂的一次燃烧固相产物,将其放置于水蒸汽高温管式炉中模拟二次燃烧。采用SEM、XRD及化学分析方法表征了水反应金属燃料的一、二次燃烧固相产物。结果表明,高活性球磨镁/铝合金水反应金属燃料推进剂具有更高的燃速和爆热值;二次燃烧产物剩余铝含量更低,二次燃烧产物反应更彻底;高活性球磨镁/铝合金能够改善其水反应金属燃料推进剂的一次燃烧效果,可提高其在二次燃烧中铝的燃烧效率。     

特种压强指数的推进剂

总结了近10年来具有平台燃烧效应的复合固体推进剂的研制成果。燃速添加剂EM_(503)及组合添加剂MT在推进剂配方中应用,可以获得具有不同燃速的、特低压强指数的推进剂配方。此类配方工艺、力学性能良好,具有实用性。同时对取得平台燃烧效应的机理进行了实验分析。     

利用高燃速化合物提高双基推进剂燃速

叙述了含有高燃速化合物的双基推进剂配方、制备工艺及燃速测试结果。高燃速化合物是三硝基间苯二酚铅、苦味酸铅和二硝基重氮酚。发现这些化合物都能较大幅度地提高双基推进剂的燃速,并随高燃速化合物的含量增加而增高。利用所测燃速结果,导出了配方中二硝基重氮酚的含量与燃速的关系式。文章初步探讨了高燃速化合物提高推进剂燃速的机理。     

Burning Characteristics and Thermochemical Behavior of AP/HTPB Composite Propellant Using Coarse and Fine AP Particles

The burning rate of AP/HTPB composite propellant increases with increasing AP content and with decreasing AP size. In addition, the burning rate can be enhanced with the addition of Fe₂O₃. The burning characteristics and thermal decomposition behavior of AP/HTPB composite propellant using coarse and fine AP particles with and without Fe₂O₃ at various AP contents were investigated to obtain an exhaustive set of data. As the AP content decreased, the burning rate decreased and the propellants containing less than a certain AP content self‐quenched or did not ignite. The self‐quenched combustion began at both lower and higher pressures. The lower limit of AP content to burn the propellant with coarse AP was lower than that with fine AP. The lower limit of AP content to burn was decreased by the addition of Fe₂O₃. The thermal decomposition behavior of propellants prepared with 20–80 % AP was investigated. The decrease in the peak temperature of the exothermic decomposition suggested an increased burning rate. However, a quantitative relationship between the thermochemical behavior and the burning characteristics, such as the burning rate and the lower limit of AP content to burn, could not be determined.     

Flammability limits and ballistic properties of fuel-rich propellants

The flammability limits and ballistic properties of composite fuel-rich propellants were studied experimentally, using PBAN/AP propellant formulations. Higher pressure and AP contents as well as smaller AP particle size were found to promote sustained combustion and to increase burning rate. The addition of potassium perchlorate (KP) in place of AP increased the burning rate pressure exponent from about 0.3 to over 0.7 at optimum conditions. Ferric oxide and copper chromite catalysts caused an increase of the burning rate by a factor of 2, while the addition of aluminum powder at the expense of the fuel binder was found to have a remarkable effect on the burning rate with a maximum increase of as high as 5-fold.     

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.     

Effects of Different Metal Fuels on the Characteristics for HTPB‐based Fuel Rich Solid Propellants

The microstructures and granularity distribution of different metal particles were investigated and the energy, sensitivity, and combustion properties of fuel rich solid propellants with different metal particles were studied in detail. It was found that the magnesium particles are more uniform than other metal powders, the mean diameter of the magnesium particles d₅₀=67.6 μm is much higher than those of the other ones, which are in the range of 7.1 μm<d₅₀<20.5 μm. Additionally, the preparation process of the Mg‐based propellant is easier than those of the other ones. The experimental results showed that the propellant containing magnesium powder was less sensitive to friction and impact (165.1 NM and 21.9 NM, respectively), whereas, the burning rates of propellants with Zr and ZrH₂ particles increased, and the pressure exponents decreased.     

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.     

Burning Rate – Pressure Relationship of NG‐PE‐PCP‐based High Energy Propellants

Nitramines are known to produce lower burning rates and higher pressure exponent (η) values. Studies on the burning rate and combustion behavior of advanced high‐energy NG/PE‐PCP/HMX/AP/Al based solid propellant processed by slurry cast route were carried out using varying percentages of HMX and AP. It was observed that propellant compositions containing only AP and Al loaded (total solids 75 %) in NG plasticized PE‐PCP binder produce comparatively lower pressure exponent (η) values similar to AP‐Al filled HTPB based composite propellants. However, energetic propellants containing high level of nitramine (40–60 %) produce high pressure exponent (0.8–0.9) values in the same pressure range. Incorporation of fine particle size AP (ca. 6 μm) and change in its concentration in the propellant composition reduces η value marginally and influences the burning rate. However, such compositions have higher friction sensitivity.     

Analysis of the Solid Combustion Products of a Mg‐Based Fuel‐Rich Propellant used for Water Ramjet Engines

A high‐pressure combustor and a metal/steam reactor were used to simulate the two‐stage combustion of a fuel‐rich propellant used for water ramjet engines. The solid combustion products from the two stages were collected and characterized by scanning electron microscopy (SEM) and X‐ray diffraction (XRD). In addition, the thermal properties of the solid products of the primary combustion were characterized by differential thermal analysis (DTA) and simultaneous thermogravimetry (TG). The burning rates at different pressures were measured and the secondary combustion process in hot steam was monitored by high‐speed cinematography. The results showed that the propellant has a good combustion performance and a high burning rate. After primary combustion, the solid product mainly contained magnesium, magnesia, magnesium chloride, and carbon. During the secondary combustion, the ignition temperature was approximately 720 °C, and two burning stages were observed. The rest of magnesium hasn’t completely reacted with hot steam until the temperature reached a value higher than 800 °C for 30 min.     

Burning Characteristics of Ammonium Nitrate‐based Composite Propellants Supplemented with Ammonium Dichromate

Ammonium nitrate (AN)‐based composite propellants have attracted much attention, primarily because of the clean burning nature of AN as an oxidizer. However, such propellants have some disadvantages such as poor ignition and low burning rate. Ammonium dichromate (ADC) is used as a burning catalyst for AN‐based propellants; however, the effect of ADC on the burning characteristics has yet to be sufficiently delineated. The burning characteristics of AN/ADC propellants prepared with various contents of AN and ADC have been investigated in this study. The theoretical performance of an AN‐based propellant is improved by the addition of ADC. The increase in the burning rate is enhanced and the pressure deflagration limit (PDL) becomes lower with increasing amount of ADC added. The increasing ratio of the burning rate with respect to the amount of ADC is independent of the AN content and the combustion pressure. The optimal amount of ADC for improving the burning characteristics has been determined.     

固体贫氧推进剂研究

系统地综述了国内外固体贫氧推进剂的研究成果，对碳氢推进剂，含镁中能推进剂和含硼高能推进剂的配方特征，燃烧特征和燃速调节方法进行了评述，提出了各类推进剂应解决的主要问题。     

Ballistic Modification of Nitramine Propellants with Special Reference to NG‐PE‐PCP‐Based High Energy Propellants

The burning rate pressure relationship is one of the important criteria in the selection of the propellant for particular applications. The pressure exponent (η) plays a significant role in the internal ballistics of rocket motors. Nitramines are known to produce lower burning rates and higher pressure exponent (η) values. Studies on the burning rate and combustion behavior of advanced high‐energy NG/PE‐PCP/AP/Al‐ and NG/PE‐PCP/HMX/AP/Al‐based solid rocket propellants processed by a conventional slurry cast route were carried out. The objective of present study was to understand the effectiveness of various ballistic modifiers viz. iron oxide, copper chromite, lead/copper oxides, and lead salts in combination with carbon black as a catalyst on the burning rate and pressure exponent of these high‐energy propellants. A 7–9 % increase in the burning rates and almost no effect in pressure exponent values of propellant compositions without nitramine were observed. However, in case of nitramine‐based propellants as compared to propellant compositions without nitramines, slight increases of the burning rates were observed. By incorporation of ballistic modifiers, the pressure exponents can be lowered. The changes in the calorimetric values of the formulations by addition of the catalysts were also studied.