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71.
为研究初容室容积变化对燃气弹射载荷与内弹道性能的影响,建立了含二次燃烧和尾罩运动边界的二维轴对称数值模型。在实验数据验证模型可靠性的基础上,研究了初容室容积变化导致流场结构和二次燃烧核心区域改变的机理,分析了弹射过程中影响建压的主导因素,得到了不同初容室容积下的流场、载荷和内弹道性能规律。结果表明:随着初容室高度的增加,燃气射流反射点由筒底转移至筒壁面,二次燃烧核心区域由发射筒上部转移至下部;对于弹底初始冲击压力峰值,容积因素占据主导,对于二次压力峰值,总压因素占据主导;导弹加速度峰值和出筒速度先减小后增加,出筒时间先变长后变短。实验装置初容室高度增加100mm,为最优内弹道设计方案。 相似文献
72.
A. Krishnaveni Neeraj Kumar Verma A.G. Menon Atanu K. Mohanty 《International journal of mass spectrometry》2008,275(1-3):11-20
We report on numerical investigations of directionality of ion ejection in stretched rectilinear ion traps (RIT). Three 4-electrode trap geometries have been investigated. In all cases, one pair of electrodes has slits at their center and the other pair has no slits. The studied traps include the RIT-S, in which the mass analyzer electrodes are symmetrically positioned around the central axis; the RIT-X, in which the mass analyzer has a stretch in the direction of the electrodes which have slits (labeled as x-direction); and the RIT-Y, in which the mass analyzer has a stretch in the direction of the electrodes which have no slits (labeled as y-direction).Our analysis has been carried out on two-dimensional (2D) fields at the centre of an infinitely long mass analyzer. The boundary element method (BEM) has been used for field computations. The trajectory of ion motion has been generated using Runge Kutta fourth order integration.Three sets of simulations have been carried out on each of the RIT-S, the RIT-X and the RIT-Y to check for directionality of ion ejection. In the first, we numerically obtain the stability region on the potential (Udc– Vrf) axes. In the second we generate an escape velocity plot with Udc=0 for different values of Vrf. In the third, we simulate the mass selective boundary ejection experiment on a single ion.In the symmetric RIT-S, as expected, all three simulations show that there is an equal probability of ion reaching the trap boundary in either of the x- or y-directions. For the stretched traps, however, the results are dramatically different. For the RIT-X, all three simulations suggest that ion destabilization at the stability boundary occurs in the x-direction. Similarly, for the RIT-Y, ions preferentially get destabilized in the y-direction. That is, ions reaching the trap boundary overwhelmingly prefer the stretch direction. 相似文献
73.
74.
Three quantitative methods, namely profilometry, high speed imaging and recoil momentum measurements using a ballistic pendulum, are used to determine the interplay of vaporization, melt displacement and melt ejection on nanosecond laser induced material removal. At low to moderate fluences (<7 J cm−2) material removal occurs via vaporization and melt displacement in aluminium. At high fluences (>7 J cm−2), material removal occurs predominantly via the explosive ejection of liquid droplets from the melt pool. 相似文献
75.
本文主要研究铝自由面微粒子喷射量随压力加载速率的关系,重点是对微射流机制的研究。用人工楔形槽作为自由面上的模拟几何缺陷,用斜波发生器技术改变加载速度,用石英传感器技术测量微粒子喷射量。研究结果表明:在楔形槽尺寸和峰值应力不变的条件下,微粒子喷射量及其最大喷射速度,均随加载速度(加载波阵面宽度的一种度量)的减小而减小;在压力加载条件不变时,发现微粒子喷射量有随几何缺陷体积的增加而增大的迹象。用HELP编码对本实验进行的二维数值模拟结果表明,在数值上与实测数据基本符合。 相似文献
76.
Qiankun Dang Fuxing Xu Xiaohua Huang Xiang Fang Rizhi Wang Chuan‐Fan Ding 《Journal of mass spectrometry : JMS》2015,50(12):1400-1408
It is well known that superimposition of some positive octopole field will benefit the performance of ion trap mass analyzer. In the radial‐ejection linear ion trap (LIT), adding some octopole field component to the main quadrupole field is usually accomplished by stretching the ejection rod pair. In this study, the effect of octopole potential and some other higher order potential on the performance of LIT mass analyzer is investigated. A simple and effective method, which is to add some octopole component by building a LIT with a pair of rectangular electrodes and a pair of semi‐circular electrodes, is reported. Its properties were studied by numerical simulations and experiments. The results showed that a certain amount of positive octopole component could be produced by simply adjusting the position and width of the rectangular electrodes. A resolution of over 1200 at m/z 609 (~1600 Da/s) was observed in this type of LIT. They also performed tandem mass spectrometry well. The device with optimum geometry for ion ejection from rectangular electrodes provided comparable performance to that for ion ejection from semi‐circular electrodes. This type of LIT design is easy for fabrication and assembly. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
77.
卢雅琳 《陕西理工学院学报(自然科学版)》2002,18(2):12-14
针对链节胎模锻存在起模困难的问题 ,设计了一套杠杆式顶出机构顶出制件 ,采用此机构可提高生产率 ,同时 ,减少了热锻件的闷模时间 ,提高模具的使用寿命。 相似文献
78.
Mrevlishvili G. M. Sottomayor M. J. Ribeiro da Silva M. A. V. Mdzinarashvili T. D. Al-Zaza M. Tediashvili M. Tushishvili D. Chanishvili N. 《Journal of Thermal Analysis and Calorimetry》2001,66(1):103-113
Journal of Thermal Analysis and Calorimetry - Bacterial viruses genome- ds-DNA -expulsion from the phage capsid is induced by temperature and is not accompanied by heat effects (temperature... 相似文献
79.
粉体成型非同时三次加压与保压脱模 总被引:5,自引:0,他引:5
论述了机械式自动式压自动成型的工艺过程,及其非同时三次加工的工作原理,介绍了克服压块脱膜弹性后效的保压脱模工作方式及其结构原理。 相似文献
80.