采用针孔照相方法测量弹丸飞行姿态

一、引言 测量弹丸飞行姿态,特别是出炮口100—200m以内的飞行姿态,是外弹道测试的重要内容。它与弹丸的飞行稳定性及射出密集度的研究有着非常密切的关系。 弹丸摆动幅值(攻角)及摆动波长的大小因弹而异,通常攻角幅值约2°～15°,波长约几米到几十米。要求至少可能测量3～5个摆动波长的攻角变化曲线。     

利用线列CCD像机交汇测量弹丸攻角

提出了一种新的测量弹丸攻角的方法。利用线列CCD像机交汇形成一光靶 ,测量弹丸通过光靶的瞬时位置 ,将获得的位置信息按时间序列进行排列后即可获得弹丸的攻角。首先分析了利用线列CCD像机交汇测量弹丸攻角的测量原理及可行性 ,在此基础上提出了实现这一目标的测量系统的组成与功能 ,然后对测量系统的攻角测量精度进行了分析和讨论。结果表明 ,在目前CCD狭缝像机还不具备实际应用条件的前提下 ,利用此方法可以解决狭缝像机不能实时测量的问题     

弹丸章动周期的光学立靶测量法

提出了一种新的测量弹丸初始弹道章动周期的方法,采用非接触式光学立靶测量原理测量弹丸章动周期测量弹丸通过立靶的瞬时位置,计算出弹丸章动角,根据多组章动角数据获得弹丸的章动周期并提出了实现这一目标的测量系统的组成与功能,对系统的攻角测量准确度进行了分析.     

基于高速面阵像机扫描成像的弹丸攻角测量方法

攻角是指飞行中弹丸的轴线与其质心运动方向的夹角,是描述弹丸飞行姿态的重要参数,以往都是采用狭缝相机来进行测量。提出了一种基于高速面阵像机测量弹丸攻角的方法。该方法是从面阵序列图像每帧中提取出固定列像元,然后按时序拼接形成一幅图像,等同于线阵扫描的图像;对于扫描速度同影像运动速度不同步时,建立了攻角计算修正模型。采用2台像机从非正交方向进行拍摄,基于面面交会原理,得到三维攻角。实测结果表明:该方法能完成弹速达到1 000 m/s的目标测试,攻角测量精度优于0.1。     

采用针孔照相法测量炮弹飞行姿态

测量炮弹的飞行姿态,特别是距炮口200米内的飞行姿态,是外弹道实验最重要的内容之一,因为飞行姿态与飞行稳定性及射击密集度的研究密切相关。当前,测量飞行姿态的方法有攻角纸靶、弹道靶道及高速摄影等。攻角纸靶简单、经济,但它对弹丸的运动有干扰,精度较低;弹道靶道能得到精确的飞行姿态数据,但必须建立一系列火花闪光照相站,耗费巨大;弹道同步照相及高速分幅照相也可测量姿态,但因精度较低,化费大,实际上没有得到广泛应用。 用在弹头上安装针孔照相机的方法,并借助一个频闪平行光源,能够直接记录攻角——时间变化曲线。此法比较简单、经济、精确,其缺点是需要回收射击的炮弹。     

二级轻气炮弹丸速度过程测量实验技术

轻气炮弹丸在膛内的速度、加速度及弹底压力是轻气炮及发射系统设计的关键参数，实验测量这些参数对完善内弹道理论、研究新型轻气炮以及对常规武器进行校验等有着非常重要的指导意义。     

平衡炮试验弹丸膛内过载计算模型及应用

平衡炮是一种两头发射的滑膛无后坐力炮。在平衡炮试验中，对弹丸膛内过载进行测试及研究是研究弹丸结构设计、壳体强度、装药安定性以及引信设计等方面的基础。     

平衡炮实验弹丸膛内过载计算模型及应用

 针对平衡炮的具体结构特点,为了精确计算弹丸膛内过载变化过程,利用经典内弹道法对某口径的平衡炮进行了仿真计算,得出了内弹道诸元随时间的变化曲线,再根据膛压与过载的关系,推导出了过载随时间变化的曲线图,理论计算与实验结果相吻合,该计算方法可为此类火炮的内弹道参数评估和弹丸设计提供依据。     

蒸汽爆炸推进机理的数值研究

蒸汽爆炸(BLEVE)是一种剧烈的相变现象,可应用于推进、发射等领域。采用VOF(Volume of Fraction)模型对蒸汽爆炸的两相流场变化过程进行了数值模拟,并根据流场参数的变化对Navier-Stokes方程中的源项进行动态优化,同时采用非结构化动网格技术追踪弹丸的运动轨迹。选取3种温度的过热水,模拟了不同填装量条件下过热水的蒸汽爆炸过程,并对流场压力、流体膨胀速率、相变过程和弹丸加速情况进行了对比分析。结果表明,蒸汽爆炸的产生条件较简单,能量转换迅速,膨胀的混合流体在数十毫秒内便可将弹丸发射出膛。     

用激光干涉仪测量弹丸在膛内的速度

测量弹丸在炮管中的运动速度是研究发射药内弹道效率的重要手段;是炮、弹设计所关心的重要问题之一。弹丸在炮管内经过发射,其速度从零到出炮口时每秒1千多米,速度变化大,在几毫秒内完成此过程。因为弹丸在炮管内运动,直接观察、测量是较困难的。     

应用高速莫尔形貌法测量飞弹偏角

本文提出了利用飞弹表面的高速莫尔形貌所包含的三维信息测量飞弹偏角的新方法。对于攻角而言,该方法可以从一张照片上,同时判读得到飞弹攻角在两个垂直面内的分量,从而简化了实验设备。文中,推导了有关计算公式,并对各个参数进行了误差分析;介绍了从静态到动态莫尔形貌的三步实验。实弹结果表明,用该方法可以精确地测量飞弹攻角。     

一种针对高速小目标的偏航角测算方法

射弹偏航角是影响电磁轨道发射装置发射精度的关键参数,为实时、高精度测量射弹偏航角,提升电磁轨道发射装置发射精度,基于双目视觉原理提出一种无需目标速度的射弹偏航角测算方法。利用高速射弹轨迹图像,通过构建像机线性成像模型解算高速射弹图像坐标,实现目标偏航角的测量。分析了光学系统参数对测量精度的影响,理论误差约为14.5 μrad。偏航角测量实验结果表明该方法能够实时、准确测算射弹偏航角,测算量偏差平均值为0.58 mrad。     

能识别弹丸飞行方向的弹丸空间炸点三维坐标测试方法

针对现有测量装置在测量近炸引信弹丸空间炸点三维坐标时存在的不足,提出了一种采用6光幕阵列配合火焰探测器测量弹丸空间炸点的三维坐标测试方法.提出的方法包含两台多光幕天幕靶、一台空间炸点火焰探测器和一台多路数据采集仪.两台多光幕天幕靶的6套光路和光电转换部件在空间构成6光幕探测阵列,当弹丸穿过6个探测光幕时,多路数据采集仪...     

用于弹道测量的实时测速同步触发仪设计

介绍了一种实时获取当发弹丸速度的同步触发系统.采用两台天幕靶和测时电路实时测量当发弹丸的速度,根据测得的速度和事先确定的靶距,计算输出测试仪器触发需要的延时值.同时,设计了滤除蚊虫、飞鸟等外界环境干扰的电路,确保输出的触发信号稳定可靠.详细介绍了系统组成、工作原理与逻辑电路的设计.设计的系统经过实弹射击试验验证,工作稳...     

激光反射式光幕探测技术研究

针对现有天幕靶探测灵敏度低、易受天空亮度影响、夜间不能工作等问题,提出了一种基于激光反射的主动式光幕探测方案,该方案采用一字线结构光半导体激光器作为主动光源,采用光学镜头、狭缝光阑、滤光片和光电倍增管组成光路探测系统。当飞行弹丸穿越一字线结构光半导体激光器和光路探测系统共同组成的探测光幕时,弹体表面反射回的部分光线被光路探测系统接收,经光电探测器件光电转换,并经后续信号处理电路对光电探测器件产生的电信号进行处理,输出与飞行弹丸穿越探测光幕面时刻相对应的模拟信号和脉冲信号。对系统光能量进行分析和计算,并通过实弹试验测试,结果表明:系统能够在夜间正常使用,灵敏度达到200倍以上弹径。     

Photonic time-stretch analog-to-digital converter employing envelope removing technique

The previously proposed differential time-stretch preprocessor can eliminate the distortions induced by the non-uniformity of optical pulse and the pulse-to-pulse variations of the optical source. However, the time-delay element in this method reduces the processing speed of the system. In this paper, we propose an envelope removing technique to mitigate these distortions and improve the time efficiency of time-stretch system simultaneously. To verify the feasibility of this technique, a comprehensive mathematical model for this technique is developed and numerical simulation is also presented. Simulation results show that this method can effectively eliminate non-uniformity and pulse-to-pulse variations in time-stretch system. This method has two times faster processing speed than the differential time-stretch preprocessor.     

A Color Holographic Reconstruction System by Time Division Multiplexing with Reference Lights of Laser

3D-TV systems by holography technique have been studied in the world. In this paper, we report a color holographic reconstruction system by time division multiplexing method with reference lights of laser. The method can reconstruct a color holographic image by switching reference lights of red, green and blue colors at certain intervals. We can observe a color holographic image using red and green lasers as the reference lights, a high minute liquid crystal display (LCD) panel as a spatial light modulator (SLM) and electro-shutters as the shuttering device of the laser lights in the optical system. This approach has some advantages. Namely, the structure of the optical system can be simple and the number of LCD panels in the optical system can be decreased.     

Visualization of the non-steady state oblique detonation wave phenomena around hypersonic spherical projectile

We studied experimentally the shock waves and combustion waves generated by a hypersonic spherical projectile in an explosive mixture. An acetylene/oxygen mixture diluted with argon (2C₂H₂ + 5O₂ + 7Ar) was used with various initial pressures (detonation cell sizes) to observe optically with a shadowgraph imaging system a shock-induced combustion (SIC), a stable oblique detonation wave (ODW), and a wave called a Straw Hat type consisting of a strong SIC and ODW. The criticality of stabilizing an ODW around a projectile is expressed by the ratio of the projectile diameter, d, to the cell size, λ, as d/λ = 3.63–4.84. Although the Straw Hat type wave in the vicinity of criticality is an unstable phenomena, it has been mainly observed by a single frame picture to date, so that it is difficult to discuss the time history of its wave structure. In this study, it was remarkable to directly carry out continuous optical observations using a high speed video camera which can continuously film 100 pictures with a 1 μs frame speed so as to allow an investigation of the sustaining mechanism of the unstable wave structure. Our results allowed the identification of an increase in unsteadiness in the relative distance between the projectile fronts and the transition points to an ODW as the time increased. They also showed local explosions in the SIC region near transition point transformed the ODW front upstream.     

Multi-optical-wavelength ultrasound-modulated optical tomography: a phantom study

We used multiple optical wavelengths to study ultrasound-modulated optical tomography (UOT) in tissue phantoms. By using intense acoustic bursts and a CCD camera-based speckle contrast detection technique, we observed variations of the ultrasound-modulated signal at various optical absorptions. The experimental variations were found to be highly correlated with predictions from Monte Carlo simulations. By irradiating the sample at two optical wavelengths, we quantitatively estimated the total concentration and the concentration ratio of double dyes in objects embedded in tissue phantoms. The results suggest that UOT can potentially provide noninvasive functional imaging of the total concentration and oxygen saturation of hemoglobin in biological tissue.