伞盘结构对大长径比发动机药柱结构完整性的影响

为了提高大长径比发动机药柱结构完整性水平,基于三维黏弹性有限元法,计算某大长径比固体发动机在温度和内压荷载联合作用下的结构响应;研究伞盘结构及其位置对药柱最大Von Mises应变的影响规律;讨论当伞盘位于药柱中部时,伞盘最大Von Mises应变随伞盘宽度、深度以及顶部圆弧半径比的变化规律。结果表明,伞盘位于药柱中部时可以有效地降低大长径比药柱的最大Von Mises应变,增加伞盘宽度、深度或选取合适的半径比均可降低伞盘结构的最大Von Mises应变。所得结论可为固体发动机设计提供参考。     

固体燃料冲压发动机飞行性能分析

固体燃料冲压发动机性能通过进气道与导弹飞行工况关联在一起,其工作过程需考虑导弹飞行参数对发动机性能的影响。与其它冲压发动机相比,固体燃料冲压发动机一个显著特点是推进剂燃烧过程不仅与推进剂配方、发动机结构和燃烧室压强有关,还取决于燃烧室入口空气参数,因此工作过程较为复杂。在国内首次建立固体燃料冲压发动机工作过程仿真模型,并分析导弹飞行马赫数和高度对发动机性能的影响规律。     

穿甲子弹偏心入射陶瓷/钢复合靶板试验

设计并进行了7.62mm穿甲子弹侵彻陶瓷/低碳钢复合靶板的弹道试验,得到了极限速度及陶瓷锥底部半径等数据。分析了锥底半径与入射速度、面板及背板厚度的关系,着重分析了偏心入射时靶板的抗弹机理。结果表明:陶瓷锥可分为破碎区和粉碎区,粉碎区半径约为面板厚度与弹丸半径之和;当弹着点距离陶瓷面板边缘大于5mm时,靶板的抗弹性能变化不大,而弹着点位于距陶瓷面板边缘小于5mm的板边区时,抗弹性能明显降低,靶板的有效防护面积应扣除板边区。     

大长径比固体火箭发动机点火瞬态过程数值分析

研究大长径比固体火箭发动机点火瞬态特性,采用守恒型N S方程描述了集点火器、燃烧室和喷管于一体的数学仿真模型,应用NND-3差分格式进行数值求解,计算结果表明,点火期间,发动机内除了压强急升之外,还存在振荡和拍击现象。     

复合固体推进剂颗粒填充模型及其统计特性分析

复合固体推进剂属于高填充比颗粒类复合材料,氧化剂和金属颗粒在基体中的随机分布使其在细观尺度具有非均质的特点。从细观尺度研究固体推进剂燃烧及力学性能时,必须考虑颗粒级配、空间分布和种类等因素的影响。采用分子动力学方法,以硝酸酯增塑聚醚高能复合固体推进剂为研究对象,将固体颗粒模型化为球形,生成其在基体内随机分布的颗粒填充模型。利用Monte-Carlo算法模拟计算颗粒填充模型细观结构的两点概率函数,并研究了颗粒填充体积分数、尺寸与级配等参数对其的影响规律。从统计意义上给出具有各态历经性、统计均匀性和各向同性特点的颗粒填充构型最小周期性代表体元尺寸,可有效减小后续研究的计算量,节约计算成本。所构建的推进剂细观几何构型及对最小周期性代表体元尺寸的计算为后续开展复合固体推进剂细观尺度燃烧、燃面处铝团聚及力学性能数值研究奠定了基础。     

Recent advances in catalytic combustion of AP-based composite solid propellants

Composite solid propellants (CSPs) have widely been used as main energy source for propelling the rockets in both space and military applications. Internal ballistic parameters of rockets like characteristic exhaust velocity, specific impulse, thrust, burning rate etc., are measured to assess and control the performance of rocket motors. The burn rate of solid propellants has been considered as most vital parameter for design of solid rocket motors to meet specific mission requirements. The burning rate of solid propellants can be tailored by using different constituents, extent of oxidizer loading and its particle size and more commonly by incorporating suitable combustion catalysts. Various metal oxides (MOs), complexes, metal powders and metal alloys have shown positive catalytic behaviour during the com-bustion of CSPs. These are usually solid-state catalysts that play multiple roles in combustion of CSPs such as reduction in activation energy, enhancement of rate of reaction, modification of sequences in reaction-phase, influence on condensed-phase combustion and participation in combustion process in gas-phase reactions. The application of nanoscale catalysts in CSPs has increased considerably in recent past due to their superior catalytic properties as compared to their bulk-sized counterparts. A large surface-to-volume ratio and quantum size effect of nanocatalysts are considered to be plausible reasons for improving the combustion characteristics of propellants. Several efforts have been made to produce nanoscale combustion catalysts for advanced propellant formulations to improve their energetics. The work done so far is largely scattered. In this review, an effort has been made to introduce various combustion catalysts having at least a metallic entity. Recent developments of nanoscale combustion catalysts with their specific merits are discussed. The combustion chemistry of a typical CSP is briefly discussed for providing a better understanding on role of combustion catalysts in burning rate enhancement. Available information on different types of combustion nanocatalysts is also presented with critical comments.     

使用I-DEAS软件进行产品结构标准的计算

介绍了产品结构(productarchitecture)的定义和研究背景.目前有若干种方法来衡量产品结构,其中一种是结合实体建模程序自动完成量化工作,文中重点介绍了此方法.采用I DEAS软件,基于Steiner方法,所编程序植入I DEAS,从而实现产品结构的计算.     

固体发动机星形药柱的形状优化分析

为了极大地提高发动机的结构完整性能,利用MSC.Nastran软件的结构优化功能,对星形药柱发动机进行了形状优化分析.探讨了发动机形状优化中位移模式和辅助模型的建立方法,根据发动机的结构和受力特点,建立了星形药柱的平面应变模型,对星形药柱的控制参数进行了灵敏度分析,并在此基础上对星形药柱进行了形状优化.优化结果表明:增大星边夹角和顶弧倒角可有效地缓解应力应变的集中程度.     

子空间预测控制在固体氧化物燃料电池中的应用

为使固体氧化物燃料电池(SOFC)输出满足一定约束的稳定电压、提高其输出功率跟踪性能,采用文献中给出的SOFC动态模型,设计了基于子空间矩阵的预测控制器。将子空间辨识和预测控制算法结合起来,直接从开环输入输出数据获得预测控制器的控制矩阵,而不须经过中间参数模型辨识的步骤。仿真结果验证了所提子空间预测控制算法(SPC)的实用性。     

论火灾现场物证的提取

火灾现场物证是火灾原因认定的证据之一,火灾现场物证的提取是关键,不同的火灾物证其提取方法不同,对火灾物证提取要求和方法进行了讨论。