共查询到20条相似文献,搜索用时 15 毫秒
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为了研究超高速碰撞产生闪光辐射的速度及角度效应,利用建立的瞬态光纤高温计测量系统结合二级轻气炮加载系统,进行了6种实验条件下的超高速碰撞实验。每组实验使用一组光纤探头,基于实验所获原始数据结合标定,通过Matlab编程处理得到了给定实验条件及光纤探头安装条件下,超高速碰撞LY12铝靶产生的闪光辐射与碰撞速度和弹丸入射角度的关系。实验结果表明,超高速碰撞LY12铝靶产生的闪光辐射在温度峰值出现前近似与碰撞速度和弹丸入射角度(弹道与靶板平面的夹角)正弦乘积的平方成正比;碰撞闪光辐射在温度峰值出现后近似与碰撞速度和弹丸入射角度正弦乘积的0.75次幂成正比,与理论推导结果基本吻合。 相似文献
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Pica Ciamarra M Lara AH Lee AT Goldman DI Vishik I Swinney HL 《Physical review letters》2004,92(19):194301
Our experiments and molecular dynamics simulations on a projectile penetrating a two-dimensional granular medium reveal that the mean deceleration of the projectile is constant and proportional to the impact velocity. Thus, the time taken for a projectile to decelerate to a stop is independent of its impact velocity. The simulations show that the probability distribution function of forces on grains is time independent during a projectile's deceleration in the medium. At all times the force distribution function decreases exponentially for large forces. 相似文献
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超空泡射弹侵彻问题的实质是特殊水下结构受到高速冲击载荷作用下的动态响应。对12.7 mm口径超空泡射弹侵彻典型水下目标壳体的毁伤效果开展研究,基于LS-DYNA有限元分析软件建立水环境中超空泡射弹垂直侵彻曲面靶板的等效模型,探讨射弹侵彻过程中动能侵彻和气泡溃灭对靶板联合毁伤效果,获得了靶板在各阶段的应力变化和结构变形规律。结果表明:侵彻靶板前,射弹着靶速度为200 m/s时的头部表面水介质压力峰值达768 N,靶板表面有明显下凹变形;侵彻靶板时,伴随着射弹动能侵彻和气泡溃灭冲击,水介质造成的影响不足动能侵彻的2%;侵彻靶板后,在靶板正面形成峰值速度为42 m/s的水射流进一步作用于破口;靶板整体弯曲变形,在200~300 m/s范围内,随着射弹着靶速度的增加,靶板弯曲形变量减小;靶板局部发生延性穿孔,射弹在水环境中具有更好的破口效果,射弹速度变化对破口尺寸影响不大。 相似文献
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Katsuki S. Akiyama H. Yamada T. Eguchi N. Maeda S. Sato K.N. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1993,21(6):755-759
Preacceleration of a projectile is important for reducing the erosion of the bore surface in a railgun. Gas guns, electrothermal guns, and other railguns are commonly used to preaccelerate the projectile. A new method, called the plasma initiation separated from the projectile (PISP) method is proposed, and its effectiveness is confirmed experimentally. A thin copper wire is placed near the edge of the railgun, and it explodes and forms a plasma that has a fast flow velocity due to the Lorentz force. This fast flowing plasma collides with the projectile, which obtains an initial velocity mainly by the momentum transfer. Since the current increases while only the plasma is accelerated, the driving force of the projectile just after the collision of the plasma with the projectile is large. The PISP method works as an inductive energy storage circuit with an opening switch 相似文献
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本文详细介绍了利用二级轻气炮发射超高速弹丸的弹托分离技术。实验结果表明采用拦截器技术进行弹托分离,不像气动力分离技术那样损失弹丸速度,可以充分发挥炮的发射性能。拦截器结构简单,很容易保证系统的同轴性。弹丸能够顺利地进入拦截器分离,分离的成功率为100%。 相似文献
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In this paper, the dynamics of a spherical projectile obliquely impacting into a two-dimensional granular bed is numerically
investigated using the discrete element method. The influences of projectile’s initial velocities and impacting angles are
mainly considered. Numerical results show that the relationship between the final penetration depth and the initial impact
velocity is very similar to that in the vertical-impact case. However, the dependence of the stopping time on the impact velocity
of the projectile exhibits critical characteristics at different impact angles: the stopping time approximately increases
linearly with the impact velocity for small impact angles but decreases in an exponential form for larger impact angles, which
demonstrates the existence of two different regimes at low and high impact angles. When the impact angle is regarded as a
parametric variable, a phenomenological force model at large impact angles is eventually proposed based on the simulation
results, which can accurately describe the nature of the resistance force exerted on the projectile by the granular medium
at different impact angels during the whole oblique-impact process. The degenerate model agrees well with the existing experimental
results in the vertical-impact cases. 相似文献
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基于强爆轰效应,提出一种新的超高速弹丸发射装置。在二级轻气炮平台上,设计内置炸药柱的三级加速腔,将二级轻气炮发射的克质量弹丸由6~7 km/s,再次加速至9~10 km/s的超高速。通过数值模拟优化设计药柱与飞片的形状,以及弹丸的树脂封装,从而抑制强爆轰产生的中心射流对弹丸的破坏,并且在短脉冲强冲击过程中,避免在直径达厘米级的铝或钛合金弹丸内的层裂破坏。数值模拟结果表明,经过优化设计的三级加速腔可以将气炮出膛速度约6.0 km/s的1.03 g铝合金弹丸加速至9.6 km/s,弹丸最终形状仍保持类球形,速度增益约1.6。 相似文献
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斜入射弹丸着靶位置立靶测量原理 总被引:11,自引:1,他引:11
常规的立靶测量装置要求弹道垂直预定靶面,当弹道不垂直预定靶面时,得到的测量结果是错误的。在终点弹道,有时很难保证靶面垂直飞行弹道。提出了一种由多光幕阵列组成的光幕立靶,可以实现小于70°入射角的弹丸着靶坐标的测量,不要求飞行弹道垂直靶面。在X和Y方向分别采用四个成固定角度的光幕来实现入射角度的测量,一次射击可得到弹丸的速度、速度方向上的空间角和着靶位置坐标。 相似文献
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基于处理裸核离子与中性原子碰撞电离过程的OBKN和ECPSSR理论模型,系统计算了不同裸核离子与中性原子碰撞K壳层电子俘获截面和直接电离截面,并与其它文献已有的理论和实验结果进行了比较.研究结果表明:碰撞能量较低时,电子俘获截面大于直接电离截面,随着碰撞能量的增加,电子俘获截面和直接电离截面均是先增大后减小且直接电离截面减小地非常缓慢,高能时,直接电离截面大于电子俘获截面.当入射炮弹离子速度接近0.67倍靶原子K壳层电子速度时,电子俘获截面达到最大值,而当入射炮弹离子速度接近靶原子K壳层电子速度时,直接电离截面达到最大值. 相似文献
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基于处理裸核离子与中性原子碰撞电离过程的OBKN和ECPSSR理论模型,系统计算了不同裸核离子与中性原子碰撞K壳层电子俘获截面和直接电离截面,并与其它文献已有的理论和实验结果进行了比较.研究结果表明:碰撞能量较低时,电子俘获截面大于直接电离截面,随着碰撞能量的增加,电子俘获截面和直接电离截面均是先增大后减小且直接电离截面减小地非常缓慢,高能时,直接电离截面大于电子俘获截面.当入射炮弹离子速度接近0.67倍靶原子K壳层电子速度时,电子俘获截面达到最大值,而当入射炮弹离子速度接近靶原子K壳层电子速度时,直接电离截面达到最大值. 相似文献
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In shooting range, projectile burst location is an important indicator. To solve the question that multi-screens across measure method cannot gain projectile proximity fuze burst location parameters when projectile close to simulation object at high altitude, the method of lateral camera assistant multi-screens across was proposed to amend the coordinates of four screens across system and realize projectile proximity fuze burst three-dimensional coordinates. The principle and existed question of four screens across system in measuring projectile burst coordinate were analyzed, and according to their measure shortcomings, the calculation model of lateral camera assistant four screens across system was set up, its amendment arithmetic was educed and analyzed, at last, the amendment three-dimensional coordinates of projectile burst location was give out based on their space geometry relation, and the measure errors were analyzed. Through experiment, the amendment measure projectile proximity fuze burst three-dimensional coordinates arithmetic was validated, and the results show the amendments measurement method is scientific and feasible. 相似文献
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推导了碰撞产生闪光的射流起爆模型,并利用建立的光纤瞬态高温计测量系统和二级轻气炮加载系统,进行了碰撞速度相近、弹丸入射角度分别为45°和60°(与靶板平面的夹角)时球状铝丸超高速碰撞天然白云石板产生闪光现象的实验测试。实验结果表明:当弹丸为LY12铝、靶板为20mm厚的天然白云石板,碰撞速度分别为1.86km/s和1.96km/s时,弹丸入射角度为45°时的闪光强度峰值大于弹丸入射角度为60°时的闪光强度峰值。 相似文献
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帧间差分法是运动目标检测最为常用的方法之一,具有算法简单、数据处理量小、易于实现等优点,因而得到广泛应用。而帧间差分法通常是根据单一的光照条件设定的固定阈值以判断是否有运动物体,因此限制了其在不同光照条件下的应用。针对上述情况,以色度、饱和度、亮度(HSL)颜色空间中的亮度值为依据,建立光强-亮度-阈值表,从而以动态的阈值调整拓展了帧间差分法在不同光照条件下的应用。通过仿真和FPGA实现了该目标检测系统,并搭建了验证测试系统。实验结果表明,当光照强度为90 W/m2时,在3.0 m/s和0.5 m/s速度下,自适应阈值的检测正确率分别达到93%和95%,与固定阈值设定较大时的检测结果相近;在0.59 W/m2的低光照条件下针对上述运动速度,检测率分别达到84%和92%,与小固定阈值检测结果相近。 相似文献
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M.W. Mancini A.L. de Oliveira K.M.F. Magalhãaes V.S. Bagnato L.G. Marcassa 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(3):317-322
In an experimental study, the multi-ionisation of metallic clusters (Nan) has been analysed in collisions with light ions in low charge states (H+, He+, He2+, O3+) at collision velocities below 1 a.u. Cluster ions are produced in charge states up to 5+. The average charge of the nano-particles
is found to increase linearly with the variation of projectile velocity and the square of the effective projectile charge,
well in agreement with the electronic stopping power of the bulk material. A fraction of 50% to 30% of the total projectile
energy loss (decreasing with velocity) is transferred into vibrational modes in good agreement with recent theoretical predictions.
Received 8 November 2000 and Received in final form 26 January 2001 相似文献
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A solution to the problem of motion of a projectile in the bore of a pneumatic line launcher equipped with a fast-acting valve of large clear opening is obtained. The results are represented in the user-friendly graphical form and include a variety of the gasdynamic and design parameters of the launcher that influence the projectile velocity. The calculated data are in good agreement with data of multiparametric experiments. 相似文献