带炮口制退器火炮发射流场数值模拟

为了研究带炮口制退器火炮发射流场结构,采用二维轴对称Navier-Stokes方程并结合标准k-ε湍流模型建立了流场数学物理模型.采用动网格技术对弹丸运动进行处理,在弹丸前后分别控制网格的生死.通过数值仿真得到了含炮口制退器膛口初始流场和膛口流场的数值分布,并对初始膛口流场和膛口流场的发展规律进行了讨论和分析.分析表明,流场数值模拟结果合理可信,该研究对膛口气流流动研究和炮口制退器设计具有指导意义.     

新型钛合金炮口制退器三维数值模拟与分析

以金属激光增材制造为技术手段,设计一种新型的钛合金航炮炮口制退器。基于三维非定常Euler方程,结合高精度Roe格式以及结构化网格技术,对带新型炮口制退器的膛口流场进行三维数值模拟,得到了小口径火炮的火药燃气速度以及冲击波的形成与发展过程。结果表明:新型炮口制退器起到分流与制退作用,多侧孔结构实现了大程度的分流效果,同时制退效率可达到29%。文中制退器的结构设计以及数值模拟仿真方法对于新型钛合金制退器的发展具有一定的参考意义。     

基于动网格的炮口制退器两相流场数值模拟

为较准确地研究火炮发射时高温高压高速的燃气射流经由炮口制退器的流场,对基于动网格的炮口制退 器两相流场进行数值模拟。利用FLUENT 软件,采用光顺和重构的非结构动网格更新方法,使用结构非结构混合网 格技术,建立炮口制退器的流场模型,对弹丸飞出炮口制退器过程中的膛口流场进行数值模拟,并对比分析了燃气 射流中的固相颗粒与气相耦合的两相流场和单纯气相流场对炮口制退器的影响。计算结果表明：考虑了两相的流场 与单纯气相流场在压强分布上存在明显的区别,可为后续炮口制退器的结构设计与优化研究提供一定的参考。     

利用消声原理降低炮口冲击波超压值

论述了利用消声原理降低炮口冲击波超压值的可行性。根据小孔扩散消声器的声压级计算公式,推导出了利用消声原理计算炮口冲击波超压值的数学计算方法。火炮发射时,当弹丸出炮口后,火药气体从膛内排空与小孔喷注类似。通过实例计算了制式炮口制退器和采用消声原理的炮口制退器的炮口冲击波超压值。计算值与实测值对比表明,在两种炮口制退器的效率基本相同的情况下,冲击波超压值可降低40%以上,且该计算方法简便易行。     

膛口装置三维流场的数值模拟及制退效率计算

基于三维非定常Euler方程,结合高精度Roe格式以及结构化动网格技术,对弹丸飞离开腔式膛口制退器过程中膛口流场的发展过程进行了数值模拟.根据数值计算结果,讨论了制退器内流场复杂三维瞬态效应的主要特征,与膛口流场的试验阴影照片相吻;根据数值计算结果对开腔式制退器的制退效率进行了计算,其结果与相关试验计算结果相符.文中方...     

一种新型炮口装置的膛口流场数值模拟

为研究一种新型炮口装置对火炮发射时膛口流场的影响,文中运用计算流体力学相关知识,采用包含动网格的膛口流场的二维非定常粘性可压缩N-S方程组进行模拟仿真。分析了在有无该装置的两种情况下,炮口流场的激波系结构形成与发展的过程。结果表明该新型膛口装置对弹丸出炮口后运动状态影响较小,炮口冲击波满足对环境及人员的要求。     

某大口径轻武器射流噪声的小波分析与数值模拟

针对某带膛口制退器的大口径轻武器射流噪声问题,在实验研究和数据分析基础上,对膛口噪声的气动特性进行探究。利用小波分析方法对实验测得的噪声数据进行分析,将膛口冲击波与膛口脉冲噪声的波形加以区分;采用计算流体力学与计算气动声学耦合算法对膛口噪声进行数值模拟,并将测点位置的噪声数值模拟结果与实验结果进行对比分析,验证该计算方法的可行性;分析了膛口制退器内的激波分布及带膛口装置的膛口噪声场指向性分布。研究结果表明：膛口噪声成分复杂,频带宽且声能较高,膛口制退器引起膛口周围流场的侧向分流,从而影响膛口噪声的指向性分布。     

高速弹丸穿越不同制退器时的膛口流场波系结构研究

基于二维非定常Euler方程,结合高精度Roe格式及结构化动网格技术,对弹丸从膛底飞离不同膛口装置过程中膛口流场的发展过程进行了数值模拟。数值计算结果清晰地揭示了光膛口以及分别加装开腔式和多孔制退器后膛口流场的不同波系结构,同时计算纹影图清楚地显示了其与弹丸相互作用及演变过程。计算结果与本课题组先前相关试验阴影照片相符。另外,根据数值流场结果,详细探讨了制退器降低后坐冲量的机理与膛口周围超压区域的分布,为制退器改进设计提供重要参考。     

带制退器的膛口燃烧流场并行数值模拟

采用三维非定常化学反应流控制方程组对带制退器的膛口燃烧流场进行了数值模拟,对流项和化学反应源项分别用TVD格式和基元反应模型进行处理,在多台PC机组成的集群并行系统中,基于域分解的思想对带制退器的三维膛口非平衡化学反应流场进行了数值计算.计算结果表明,膛口制退器能削弱膛口流场激波的强度,抑制二次焰的产生.     

反器材步枪膛口装置设计与仿真

某反器材步枪膛口装置为两腔冲击式制退器,由于结构设计原因,枪手在射击时,制退器后喷的火药燃气会产生较大的冲击波﹑声响及火焰,对射手容易造成伤害。为了解膛口装置制退效率的影响因素,优化其结构使其在相同制退效率下,减小冲击波等对射手的伤害,根据三维非定常Euler方程,利用Fluent软件对弹丸飞离改进后膛口装置时的流场建模并进行仿真,并利用Matlab软件编程对其制退效率进行了数值计算,两者结果相符。结果分析表明:优化后制退器可在保证相同制退效率下,有效地减小冲击波大小,可为解决同类问题提供有价值的借鉴。     

Nitrosation and Nitration of Tetraacetyldibenzylhexaazaisowurtzitane

Tetraacetyldibenzylhitane (TADBIW) was subjected to debenzylation by nitrosating with inorganic materials available commercially to synthesize tetraacetyldinitrosohexaazaisowurtzitane (TADNSIW). TADNSIW was purified, and its structure was determined by FTIR, 1H NMR, MS and element analysis. The debenzylation reaction of TADBIW gave quantitative benzaldehyde as a by-product. This indicates that the reaction produces an imine cation as an intermediate. Hexanitrohexaazaisowurtzitane (HNIW) was prepared from unpurified TADNSIW with the yield over 96.0 % and the purity more than 98.0 %. And the mechanism of the reaction from TADNSIW to HNIW is proposed to be oxidation of nitroso and nitration of acetyl on the molecule of TADNSIW, This reaction system involved is simple, and the reaction can complete within a short time and under mild conditions. The product can be easily to separate and the waste disposed readily.     

A Robust Algorithm for Watermarking 2D Vector Maps with Low Shape-Distortions

The technique of watermarking has been introduced into 2D vector maps for many potential applications such as protecting the copyright of important GIS （geographical information system） data and tracing the data source of military maps. In most previous works, although the validity of the map data could be preserved during the embedding procedure, the shape-distortions of the map elements are usually neglected which would tend to degrade the invisibility of the watermarking schemes. A shape-preserving algorithm for watermarking 2D vector maps is presented in this paper. A 1D distance sequence extracted from the original map is adopted as the cover data instead of 2D coordinates. A watermark bit is represented by changing the distributions of the cover data. The embedding procedure induces lower shape-distortions than in former works. Experimental results indicate better invisibility of the proposed scheme, as well as its robustness to certain attacks such as map simplification, interpolation, additive noise and most geometric transforms.     

Open Rule-setting System Applied to Conceptual Design of Engines

Open rule-setting method advanced in this paper concentrates on providing designers of engines with a convenient way to express their design innovations and develop the expected prototypes in the early CAD stage, and constitute effective models for the following analysis process of CAE and CAPP. The problems arisen in the process of conceptual design with the traditional experience-based development method are analyzed. Based on those analyses, open rule-setting method is presented and some associated technical problems are discussed. The functional framework of open rule-setting system was built as software engineering methods. The speciality of the engine product as a kind of complex product and the requirement of the engine product based on its structural particularity to rule-setting system are considered carefully. A demonstration is supplied to illustrate how the open rule-setting method enhances the efficiency and quality of the engine conceptual design.     

Research on Linux Network Device Driver

By analyzing the working principle of Linux network device driver, discussing the Linux network driver structure and its key technologies, the general network driver structure and its design methodologies in Linux system are summarized. Through modifying the network device driver of Linux device driver 3rd version snull, c and improving the COW technology, the Zero-Copy technology in Linux （kernel version 2.6.11 ） is implemented. In the end, the success test tells us that the thorough analysis of network device driver is the foundation of many applications, and it also provides a certain improvement to a lot of real applications, even to military application development.     

Method for Measuring Velocity of Warhead Fragments Based on Photoelectric Detection

For measuring velocity and impacting position of single fragment of warhead, a non-contact measuring method is proposed, in which a six-light-screen array, a position indicator, a multi-channel chronograph and a computer are used.The principle of measurement is described. The key device of the system is a light screen array sensor which consists of six light screens allocated with certain geometrical parameters. When the fragment flies through the light screen array, the time of passing through each of the screens is recorded by the multi-channel chronograph. According to the time data and the geometrical parameters of the array, the velocity vector and the location of the fragment can be calculated immediately. The presented method can be used to locate the fragment and to measure the real velocity on its flying direction. It can also be used to measure the velocity of a fragment swarm after the system is engineered further.     

数码电子雷管中影响点火头性能因素分析

阐述了数码电子雷管中,点火药剂细结晶三硝基间苯二酚铅（LTNR）的制备工艺;从点火药剂的种类、加入黏合剂的质量分数、桥丝直径、点火头的电阻值、防潮漆的蘸涂等方面对点火头性能的影响因素进行了探讨;通过震动试验、并联起爆试验、延期精度检测与考核,试验结果表明：一次性合成的细结晶LTNR是制造数码电子雷管点火头较为理想的点火药剂,按技术要求生产的点火头性能指标能够满足行业标准要求。     

Improvement and Experiment of the Reamer in Vibra Cutter Against Wave Edge of Titanium Sheet Alloy Parts

By analyzing the influencing factors of part quality making of sheet alloy of titanium by vibra cutter, the shape of upper reamer is set as cylinder and wedge-shaped form, and the lower reamer as plain and hemicycle form, and its main structural parameters are defined as well. Then it is validated further that such improved vibra cutter reamer can be used to process curve-edged parts of titanium alloy sheet. The experimental result shows that the titanium alloy sheet parts processed by above equipment have no sharpen angles for convex parts and evident crevasse of concave-edged part. In summary, such improvement can eliminate the free-waved edge and improve the manufacture quality of titanium alloy sheet parts greatly.     

Experimental Study on the Small Flyer Initiating Behavior of Fine-grained Explosives

The initiating behavior of fine-grained explosives by small flyer is studied. The diameter of small flyer in this device is 1 ram. The test results indicate that the granularity of explosives has great effect on its flyer initiating sensitivity.The flyer initiating sensitivity of the fine-grained explosives is higher and the critical initiating energy is lower than that of common explosives. For common explosive, the flyer initiating sensitivity increases as the density is reduced. But for the fine-grained explosive, the test results are exactly opposite.     

Algorithm for Multi-laser-target Tracking Based on Clustering Fusion

Multi-laser-target tracking is an important subject in the field of signal processing of laser warners. A clustering method is applied to the measurement of laser warner, and the space-time fusion for measurements in the same cluster is accomplished. Real-time tracking of multi-laser-target and real-time picking of multi-laser-signal are introduced using data fusion of the measurements. A prototype device of the algorithm is built up. The results of experiments show that the algorithm is very effective.     

Influence of Installing Error on the Surface Shape Precision of the Axial Symmetry Aspheric Workpiece in Lapping

A method to calculate the surface shape error, which is caused by the installing error between the workpiece and the lapping tool in the process of form lapping, is proposed. The mathematical model which the installing translation error influences on the workpiece surface shape error is established. The changing rule of the error is simulated through the calculating example of the paraboloid workpiece. The results indicate that the surface shape error of the workpiece is increasing with the increase of the installing translation error, it is also increasing gradually along the center point of the curve surface to the edge, and the influence is severer to the curve surface with great curvature than that of the small curvature when the translation error is the same.