高速水射流倒空弹体装药安全性研究

本文阐述了高速水射流倒空弹体装药的机理,建立了确定水射流引爆炸药的临界速度的模拟实验方法和模型,进行了高速水射流冲击炸药的安全性试验,并对试验结果进行了分析,证明在工作泵压下高速水射流倒空弹体装药安全、可靠。     

平面B—样条曲线的拐点定理

利用插入节点的算法,本文研究了Ｂ—样条曲线的形状,得到了Ｂ—样条曲线拐点的一个定理。该定理描述了当控制多边形只有一个拐向点时Ｂ—样条曲线的拐点、尖点和二重点的关系。此项研究对于工程应用中的ＣＡＤ有较实际的指导作用。     

载人飞船标准返回轨道设计

本文研究载人飞船三自由度标准返回轨道的设计方法。基本的设计思想是在返回坐标系中建立飞船返回轨道运动方程,用非等值的速度滚动角γｖ（ｔ）使飞船再入过载均匀化及减小标准返回轨道与升力失控时自旋轨道的航程差,并引入侧向制导思想解决γｖ（ｔ）的反向问题。仿真中用二重迭代方法确定有关参数,避免了参数选择的盲目性。仿真计算表明,本文提出的设计思想具有良好的实用价值。     

基于CFD的磁射流抛光去除机理分析

应用计算流体动力学(CFD)方法分析了一种新型精密抛光技术——磁射流抛光的材料去除机理。磁射流抛光中,含有磨料的磁流变液射流被喷嘴出口附近的局部外加纵向磁场磁化,产生准直的硬化射流束来进行相对远距离的精密抛光。介绍了磁射流抛光的原理和实验装置,分析了磁流变液聚束射流的形成,通过一系列定点抛光实验研究了磁射流抛光工艺的材料去除分布特征,利用计算流体动力学的方法分析了垂直冲击和倾斜冲击情况下,磁流变液射流与工件表面相互作用时径向流场功率密度的分布特征。实验结果和仿真计算结果表明:磁流变液射流在工件表面径向扩展流动产生的径向剪切作用导致了材料去除;CFD方法能模拟抛光区去除率的三维分布,因此可以准确地预测抛光区形状。     

单兵火箭燃气射流噪声抑制的实验研究

为了能够有效抑制单兵火箭发射时的燃气射流噪声,设计了液体水圆柱形平衡体安置在火箭发动机后面,对平衡体降噪进行实验研究。在实验中利用压电式传感器测得了发射筒周围的冲击波超压值,与没加液体水平衡体实验测得的超压值相比较,发现放液体水平衡体时在改进发动机推力性能的同时,降低了整个观测区域的噪声,尤其是射流上游,起到了显著的降噪效果,并分析了火箭燃气射流与液体水平衡体相互作用的机理。实验结果对单兵火箭发射的噪声防护问题研究提供了科学依据。     

超声辅助喷射电沉积Ni镀层的表面形貌及硬度

试验以直接超声方式,在喷射电沉积装置的基础上加载超声设备,分别在20℃和50℃两种镀液温度下在A3钢基体上制备了加载超声和不加载超声Ni镀层,研究了超声波及温度对Ni镀层表面形貌和硬度的影响。试验结果分析表明：在20℃条件下,超声可避免镀层裂纹的产生,提高镀层的硬度;在50℃条件下,超声可细化镀层的组织,且可显著提高镀层硬度;超声波对喷射电沉积层组织和性能的影响机理主要在于超声空化引起的析氢减少、细晶强化和加工硬度。     

横向运动板干扰聚能射流的数值模拟

基于有限元分析软件ANSYS/LS-DYNA和LS-PREPOST,用ALE算法对射流垂直侵彻横向运动防护板的过程进行模拟分析。防护板在不同速度下干扰射流时,对防护板和后效板上的开坑形状进行分析,并计算后效板上的最终侵深及射流轴线上的速度降,得到射流在横向防护板作用下后效板侵深及射流轴线上的速度降随防护板速度变化的曲线。结果表明,防护板抗射流侵彻能力随防护板速度的增加而增强,尤其是防护板横向速度在0～100m/s增加时,抗射流侵彻能力增强较为明显。     

Theoretical and numerical simulation study on jet formation and penetration of different liner structures driven by electromagnetic pressure

The use of a shaped liner driven by electromagnetic force is a new means of forming jets. To study the mechanism of jet formation driven by electromagnetic force, we considered the current skin effect and the characteristics of electromagnetic loading and established a coupling model of"Electric—Magnetic—Force"and the theoretical model of jet formation under electromagnetic force. The jet formation and penetration of conical and trumpet liners have been calculated. Then, a numerical simulation of liner collapse under electromagnetic force, jet generation, and the stretching motion were performed using an ANSYS multiphysics processor. The calculated jet velocity, jet shape, and depth of penetration were consistent with the experimental results, with a relative error of less than 10％. In addition, we calculated the jet formation of different curvature trumpet liners driven by the same loading condition and ob-tained the influence rule of the curvature of the liner on jet formation. Results show that the theoretical model and the ANSYS multiphysics numerical method can effectively calculate the jet formation of liners driven by electromagnetic force, and in a certain range, the greater the curvature of the liner is, the greater the jet velocity is.     

Chain damage effects of multi-spaced plates by reactive jet impact

Chain damage is a new phenomenon that occurs when a reactive jet impacts and penetrates multi-spaced plates.The reactive jet produces mechanical perforations on the spaced plates by its kinetic energy(KE),and then results in unusual chain rupturing effects and excessive structural damage on the spaced plates by its deflagration reaction.In the present study,the chain damage behavior is initially demonstrated by experiments.The reactive liners,composed of 26 wt％Al and 74 wt％PTFE,are fabricated through a pressing and sintering process.Three reactive liner thicknesses of 0.08 CD,0.10 CD and 0.12 CD(charge diameter)are chosen to carry out the chain damage experiments.The results show a chain rupturing phenomenon caused by reactive jet.The constant reaction delay time and the different penetration velocities of reactive jets from liners with different thicknesses result in the variation of the deflagration position,which consequently determines the number of ruptured plates behind the armor.Then,the finite-element code AUTODYN-3D has been used to simulate the kinetic energy only-induced rupturing effects on plates,based on the mechanism of behind armor debris(BAD).The significant discrepancies between simulations and experiments indicate that one enhanced damage mechanism,the behind armor blast(BAB),has acted on the ruptured plates.Finally,a theoretical model is used to consider the BAB-induced enhancement,and the analysis shows that the rupturing area on aluminum plates depends strongly upon the KE only-induced pre-perforations,the mass of reactive materials,and the thickness of plates.     

Investigate the effects of magnetic fields on the penetration ability of a shaped charge jet at different standoffs

The influence of a magnetic field on the stability of a shaped charge jet is experimentally investigated at standoffs of 490, 650 and 800 mm. The experimental results without and with the magnetic field are compared in terms of the shaped charge jet form, stability and penetration ability. A theoretical model based on one-dimension fluid dynamics is then developed to assess the depth of penetration of the shaped charge at those three standoffs and magnetic conditions. The results show that the penetration capability can be enhanced in more than 70% by the magnetic field. The theoretical calculations are compared with the experimental results with reasonably good correlation. In addition, the parameters introduced in the theory are discussed together with the experiments at three standoffs studied.