Nitryl Cyanide,NCNO2

The elusive nitryl cyanide, NCNO₂, has been synthesized and characterized. It was prepared in good yield, isolated by fractional condensation, characterized by NMR and vibrational spectroscopy, and studied by theoretical calculations. Nitryl cyanide holds promise as a high energy density material (HEDM) and might also prove useful as a HEDM building block. The simplicity and inherent stability of nitryl cyanide, together with the known multitude of nitriles in interstellar space, suggest that the compound might also be a potential candidate for observations in atmospheric and interstellar chemistry.     

基于空中发射的运载火箭气动特性实验研究

为了研究空中发射运载火箭的气动特性,本文针对15°半顶角的圆锥-圆柱组合体火箭模型,在1.2m×1m的低速风洞进行实验研究。利用六分量天平测量0°α80°、60m/s以下8个速度的力和力矩特性,基于圆锥底部的雷诺数范围由0.129×106到0.456×106。实验结果显示,随着迎角的增加,火箭流场经历了附体流动、对称旋涡、非对称旋涡到类卡门涡街的变化历程,旋涡的变化决定了火箭的气动特性。特别是30°α70°的大迎角区域,侧力受雷诺数的影响明显,反映了雷诺数变化对火箭流场亚临界区域和临界区域的影响规律。为提高火箭纵向稳定性和姿态的调整,设计了收敛-扩张形尾部并进行了实验验证。研究结果可为空射火箭的外形设计和稳定性分析奠定一定的理论基础。     

基于CATIA的固体火箭发动机系统设计

发动机图形绘制与性能计算是火箭设计的关键步骤,通过对固体火箭发动机设计过程的分析,提出CATIA参数化图形绘制技术;以单孔管状装药发动机为例,建立了发动机燃烧室与喷管模型,在VC环境下利用CATIA Automation二次开发技术实现了燃烧室与喷管参数化设计,完成了两者装配与动态显示;利用Matcom实现内弹道压力时间曲线计算,发射段轨道分析;最后完成系统软件编制;实际使用情况表明,使用该软件可快速构造发动机,进行全面的性能分析,为固体火箭发动机方案论证与初步设计提供了有力的工具。     

温度循环载荷对柔性接头界面损伤的影响

固体火箭发动机在生产、运输和储存的过程中会受到环境湿热和老化载荷的作用,导致柔性接头界面的力学性能产生退化.为研究柔性接头界面力学性能退化对界面损伤的影响规律,基于双线性内聚力模型建立了一种描述界面力学性能退化的数学模型.以某柔性接头为研究对象,为便于研究,以温度循环载荷代替环境老化载荷开展了界面损伤分析,并采用ABAQUS 6.14进行了仿真.结果 表明,与后法兰粘接的界面损伤程度最大.当温度循环周期达到672次时,界面13和界面14的损伤程度分别由初始状态的2.9％和4.3％增加到5.2％和8.2％,增幅分别高达81.2％和91.7％.同时,温度循环载荷会加速柔性接头的界面损伤.该界面力学性能退化模型可为柔性接头老化研究提供参考.     

固体火箭发动机羽流辐射光谱测温方法研究

固体火箭发动机羽流具有高温、高速与强辐射特征,羽流温度是发动机工作状态与性能的重要表征参数。准确测量固体火箭发动机羽流温度对了解发动机内部燃烧情况以及发动机综合性能具有重要的参考价值。随着激光与光谱学的发展,激光光谱技术逐步应用于固体推进剂燃烧及发动机羽流温度测量。辐射光谱测温法通过测量火焰辐射光谱来实现温度的非接触在线测量,具有测温范围宽、响应快及可靠性高等优点,可应用于固体火箭发动机羽流温度测量。在此提出了基于火焰辐射光谱的固体火箭发动机羽流温度测量方法,采用350～1 000 nm波段光纤光谱仪搭建了发动机羽流火焰辐射光谱测量系统,利用标准辐射黑体炉开展光谱仪响应系数标定,获得响应系数随波长的变化曲线,并以此用作羽流辐射光谱数据修正。之后将该测量系统应用于标准Φ118固体火箭发动机地面试验,开展典型12%铝质量含量推进剂发动机羽流辐射光谱实验测量,选取不同时刻羽流辐射光谱分析了发动机羽流辐射光谱特征,并利用双色法灰性判断原理对羽流火焰灰体特性进行讨论,验证在675～745 nm波段发动机羽流火焰辐射可近似认为灰体,该波段辐射率随波长变化最大相对偏差为4.01%,相对均方差为1.53%。因此,基于普朗克辐射定律开展辐射光谱拟合参数获得不同时刻羽流温度与辐射率参数,并讨论测量结果与发动机工作状态的关系。最后,开展12%,15%与19%铝质量含量的不同推进剂配方固体火箭发动机羽流辐射光谱测量,将辐射光谱法温度测量值与理论热力计算值进行比较,两者最大偏差值为5.40%,讨论了不同铝含量推进剂发动机羽流辐射光谱特征,并结合温度与辐射率测量结果,分析了固体推进剂铝含量对辐射光谱、羽流温度及辐射率的影响。通过固体火箭发动机羽流辐射光谱测温方法研究,为固体火箭发动机性能评估及推进剂配方优化等研究提供了有效的羽流参数测量手段。分析获得的推进剂铝含量对发动机羽流辐射光谱、温度及辐射率参数的影响,为降低固体发动机羽流特征信号提供了重要的实验数据支撑。     

A numerical investigation of side‐loads resulting from rigid body motions of an overexpanded engine nozzle

A numerical model for fluid–structure interactions is presented. Its purpose, within the context of 2D overexpanded engine nozzles, is to improve understanding of interactions between side‐loads and rigid body rotations, and more generally of the underlying physics between a shock in motion and nozzle movements. The model is based on three different solvers, for fluid, structure and mesh deformation respectively, which are linked to a coupling scheme in a parallel environment. In particular it is shown that the nozzle has a natural torsional frequency for which the measured side‐loads are the greatest. This phenomenon is associated with a transversal wave in the flow between the two internal walls of the nozzle. For free coupling cases, our calculations go some way to explain how the mechanical energy is dissipated with a transfer of energy to the shock that encounters the largest motions to dissipate it. It has also been observed that the compression shock may adopt a quasi‐steady state response with regard to nozzle rotations at low frequencies, whereas this will no longer be the case at higher frequencies, where a phase shift may occur between side‐loads and rotational position. This study is aimed at enhancing the only current aeroelastic stability model for overexpanded nozzles (AIAA, 29th Joint Propulsion Conference and Exhibit, Monterey, CA, 28–30 June 1993). Copyright © 2010 John Wiley & Sons, Ltd.     

Carbon Nanostructures Derived through Hypergolic Reaction of Conductive Polymers with Fuming Nitric Acid at Ambient Conditions

Hypergolic systems rely on organic fuel and a powerful oxidizer that spontaneously ignites upon contact without any external ignition source. Although their main utilization pertains to rocket fuels and propellants, it is only recently that hypergolics has been established from our group as a new general method for the synthesis of different morphologies of carbon nanostructures depending on the hypergolic pair (organic fuel-oxidizer). In search of new pairs, the hypergolic mixture described here contains polyaniline as the organic source of carbon and fuming nitric acid as strong oxidizer. Specifically, the two reagents react rapidly and spontaneously upon contact at ambient conditions to afford carbon nanosheets. Further liquid-phase exfoliation of the nanosheets in dimethylformamide results in dispersed single layers exhibiting strong Tyndall effect. The method can be extended to other conductive polymers, such as polythiophene and polypyrrole, leading to the formation of different type carbon nanostructures (e.g., photolumincent carbon dots). Apart from being a new synthesis pathway towards carbon nanomaterials and a new type of reaction for conductive polymers, the present hypergolic pairs also provide a novel set of rocket bipropellants based on conductive polymers.     

轻型火箭发射噪声场的分布特性

为了解小火箭发射噪声特性及其在喷口外围的声压场分布规律,针对燃气射流产生噪声问题进行了实验研究和数值计算。讨论了超声速射流噪声的3个主要成分(湍流混合噪声、啸音和宽带激波相关噪声)及相关特点,指出它们产生的根本原因是湍流射流的速度扰动。通过分析不同实验测点的射流噪声声压级峰值,得到了燃气射流噪声在轴向和径向上的分布规律,即随着离喷口距离的增大,轴向噪声的衰减程度大于径向。在实验基础上,利用大涡模拟与FW-H(Ffowcs Williams-Hawkings)声学比拟相结合的方法对燃气射流噪声的声学特性进行计算。结果表明,此方法获得的计算结果与实验结果吻合较好,可为进一步研究射流噪声控制提供参考。     

火箭配电器测试系统设计

火箭配电器作为箭上电气系统的重要部件,对火箭飞行试验起着至关重要的作用;配电器测试直接反映其各项功能达标情况,测试方法的优劣会影响对配电器性能的评价高低;配电器测试系统以加固计算机为开发平台,通过PXI数据采集板卡对调理后的信号进行采集和控制,并在显示器上显示测试结果与数据,从而完成配电器的各项功能测试;测试系统原理样机测试某箭上配电器,比较测试值与设计值结果相符,可以得出系统设计可行、可靠;该测试系统大大改进了以往的测试手段,具有体积小、可靠性高、易于携带等优点。