火箭发动机尾焰红外辐射特性的数值模拟

建立火箭发动机尾焰红外辐射传输的有限体积离散模型,采用逐线积分方法计算气体光谱吸收系数,计算不同组分的尾焰红外辐射特性,得到组分分布对液体火箭发动机尾焰红外辐射特性的影响规律.     

复燃对氢氧火箭发动机尾焰流场及辐射特性影响数值研究

为深入研究复燃对氢氧火箭发动机尾焰流场及辐射特性的影响,以氢氧发动机喉部截面参数为入口条件,采用耦合Realizable k-ε湍流模型的三维N-S方程,考虑尾焰复燃反应影响,利用PISO算法求解得到尾焰流场参数。在此基础上,通过气体辐射传输方程和大气透过率计算模型SLG对尾焰辐射特性进行计算,对比复燃反应对尾焰流场及其辐射特性的影响。结果表明,复燃反应对氢氧发动机尾焰流场计算影响较大,使温度场以及燃烧产物的质量分数大幅增加,从而导致尾焰的辐射特性增强,因而在氢氧发动机尾焰流场和辐射计算中,考虑复燃反应是极为必要的。     

多喷管液体火箭动力系统尾焰辐射特性研究

为研究多喷管液体火箭动力系统尾焰辐射特性,以液氢/液氧和液氧/煤油发动机组成的多喷管动力系统为模型,采用CFD技术对尾焰流场进行计算,利用气体辐射传输方程和大气透过率计算模型对尾焰辐射特性进行计算,结果表明:复燃反应主要发生在尾焰的边界与空气掺混区域,导致尾焰的辐射特性增强;随着飞行高度及观测角的增加,尾焰辐射特性逐渐增强;可视化计算可以有效捕捉到尾焰流场的结构。     

矩形喷管外尾焰红外辐射特性的数值计算

为了掌握矩形喷管外尾焰的红外辐射光谱特性和强度分布,建立了矩形喷管的几何模型,采用Fluent6. 3 软件对矩形喷管外三维流场进行数值模拟,得到尾焰流场的温度、压强和密度等数据,并根据尾焰的特点确立红外辐射核心计算区域。采用洛伦兹线型的统计窄带模型,求出尾焰在某一窄带的平均吸收系数;采用有限体积法求解了气体介质中辐射传输方程;计算得到了矩形喷管外尾焰的红外辐射光谱特性与在3 ~5 滋m 波段的总强度分布。结果表明:矩形喷管外尾焰为扁平状,其宽边对称面内的红外辐射强度大于窄边对称面内的红外辐射强度,并且尾焰辐射在2. 7 滋m 和4. 3 滋m 处出现了2 个辐射峰。     

数值模拟液体火箭尾焰流场和红外辐射特性

为了研究液体火箭尾焰的流场及红外辐射特性,建立了一个相对完整的计算模型,分别使用FLUENT软件和有限体积法(FVM)计算尾焰流场和红外辐射特性,然后使用通用大气辐射传输(CART)软件计算大气透过率,并验证了模型的正确性。利用此模型研究了典型条件下火箭尾焰的流场及红外辐射特性。结果表明,尾焰在垂直于轴线方向的辐射强度最大,并集中在2.5’3.0μm和4.2’4.7μm两个波段,在10km高空大气对2.6’2.9μm和4.1’4.6μm两个波段的辐射吸收较强。     

某型液体火箭发动机喷注参数与尾焰红外图像特征研究

为了通过某型液体火箭发动机尾焰红外特征监测推力室喷嘴雾化状态,采用多学科仿真技术,耦合蒸发、燃烧和传热过程,建立了三维非稳态推力室蒸发-燃烧-尾焰场一体化仿真模型;采用尾焰图像识别方法,开展液体火箭发动机喷注参数与尾焰红外图像特征之间关系的研究。对比热试车尾焰红外图像特性表明,仿真模拟结果准确可靠。     

双机并联氢氧火箭发动机尾焰流场特性三维数值仿真研究

以氢氧火箭发动机为模型,采用耦合可实现k-ε湍流模型的N-S方程,对发动机在地面发射阶段双机并联工作状态下的尾焰流场进行数值仿真研究,得到尾焰流场的各项参数分布及其变化规律,与理论分析结果对比,证明了算法的有效性和正确性,为开展多台发动机并联工作下尾焰的撞击和辐射特性等研究奠定了基础。     

弹道导弹主动段红外成像特征仿真分析

为降低低轨导弹预警卫星的虚警概率,文中在分析弹道导弹主动段红外辐射特征的基础上,通过建立尾焰的几何特征模型和红外特征模型来描述导弹主动段的红外成像特征,并运用模型计算尾焰的红外辐射分布,构建了导弹尾焰的仿真图像,仿真图像能够准确反映导弹尾焰的红外图像真实情况,为有效识别导弹,提高导弹预警的准确性提供重要参考.     

偏二甲肼/四氧化二氮火箭发动机尾焰流场特性三维仿真研究

以偏二甲肼/四氧化二氮（UDMH/NTO）火箭发动机为研究对象,采用κ-ε湍流模型,运用PISO算法分别对发动机内流-场和尾焰流场进行三维仿真。采用相同方法计算液氢/液氧（LH2/LOX）火箭发动机尾焰,仿真结果和试验结果吻合得较好,证明了计算模型的正确性与有效性;同时对比分析了UDMH/NTO发动机与LH2/LOX发动机尾焰流场特性。结果表明,两者具有相似的温度和马赫数变化趋势,但是UDMH/NTO发动机尾焰核心区温度相对较低,而LH2/LOX发动机尾焰将更快衰减至亚声速射流。     

导弹喷焰流场与凝结尾迹的工程计算方法

为快速预估飞行器喷焰流场及其在一定空域内产生的凝结尾迹,为飞行器目标红外辐射研究提供条件,采用一种工程模型对含复燃效应和水汽凝结效应的喷焰流场进行计算分析。模型以燃气射流的一维流动理论、湍流混合以及化学平衡条件为基础建立控制方程,并采用四阶Runge-Kutta方法进行求解计算。模型校验和分析表明,该工程计算方法能够获得喷焰流场射流区的典型参数,并具有较高的计算效率。     

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.