共查询到20条相似文献,搜索用时 156 毫秒
1.
2.
为了对磁驱动实验提供高置信度的数值模拟,需要开展磁流体力学程序的验证与确认。采用人为解比较法、网格收敛性研究和与成熟程序比较等方法,对二维磁驱动数值模拟程序MDSC2进行了程序验证。数值模拟表明:MDSC2程序正确地表示了磁流体力学模型,其中热扩散、磁扩散的离散格式具有二阶收敛精度。采用与磁驱动实验相比较的方法,进行了MDSC2程序的确认。对聚龙一号装置上的PTS-061发次磁驱动单侧飞片发射和PTS-122发次磁驱动双侧飞片发射实验进行了模拟,模拟的飞片自由面速度与实验测量的飞片自由面速度相一致;对FP-1装置上的固体套筒实验进行了模拟,模拟的套筒内外半径与实验测量结果相一致。MDSC2程序能正确模拟磁驱动单侧飞片发射、磁驱动双侧飞片发射和磁驱动固体套筒等磁驱动实验。 相似文献
3.
4.
钝感炸药爆轰产物驱动金属飞片的研究工作直接同武器设计相联系。为探索研究爆轰产物驱动金属飞片的运动规律及金属材料本构关系对爆轰产物驱动飞片自身飞行的影响,用任意反射面速度干涉仪VISAR(Vclocity Interfcrometer Systcm for Any Rcflector)对不同厚度的铜半球飞层上多个点的速度历程进行了测量,得到了飞层运动的速度-时间曲线,给理论分析提供了实验数据。 相似文献
5.
在二维单介质磁驱动数值模拟程序(MDSC2)的基础上,采用局部结构整体非结构的网格拼接方法,研制了处理滑移界面的二维多介质程序。二维多介质程序解决了单介质程序无法处理的电极与飞片之间相互作用的模拟问题,能更准确地模拟磁驱动发射实验的飞片状态。计算结果表明:发射飞片的自由面部分始终保持固体密度状态;自由面速度历史和VISAR测量的速度曲线相吻合;飞片中间部分在电流加载过程中始终具有良好的平面性,飞片两端出现拖尾质量,产生不稳定性,这是由于飞片两端与飞片中间部分的磁场强度分布不同造成的。 相似文献
6.
在二维磁驱动数值模拟程序MDSC2中增加了LiF材料的材料参数和功能模块,使MDSC2程序具有了求解带窗口磁驱动准等熵压缩实验的能力。采用MDSC2程序,对大电流脉冲功率装置上的exp-3-window、exp-6-window带窗口磁驱动准等熵压缩实验进行了模拟。数值模拟结果表明,二维磁驱动数值模拟程序MDSC2能正确模拟带窗口磁驱动准等熵压缩实验exp-3-window和exp-6-window的全过程,模拟的飞片/窗口界面速度在飞片/窗口界面速度的上升阶段、峰值附近和卸载阶段与实验测量基本一致,验证了新程序的计算有效性。MDSC2程序对带窗口磁驱动准等熵压缩实验的正确模拟有助于磁驱动样品物性实验的研究。 相似文献
7.
采用Gurney理论,建立了激光作用复合膜体驱动飞片的理论计算模型。通过修正膜体材料的激光能量吸收系数,对激光作用复合膜体结构形成的飞片速度进行计算,分析了膜体材料和结构组成对飞片速度的影响,确定了形成高速飞片的复合膜体结构。进行了强激光作用复合膜体驱动飞片实验,采用压电薄膜测量了飞片到达不同距离的时间,计算得到飞片的速度和加速度。结果表明:不同激光能量作用下复合膜体飞片的加速特征基本相似,激光能量的变化对飞片加速时间的影响较小,飞片速度随着光爆层厚度的增加呈先增大后减小的趋势;对应于不同的激光能量,光爆层存在最优能量吸收厚度。 相似文献
8.
多点激光干涉测速系统和电探针技术均可用于测量高速运动物体的运动参数,为了相互验证测试结果,分析测试系统各因素对测量精度的影响,在平面爆轰波驱动飞片的实验中,利用多点激光干涉测速系统和多组电探针,同时测量金属飞片的自由面速度。将多点激光干涉测速系统测得的飞片速度-时间曲线进行积分,得到飞片的位移-时间曲线,并与电探针测得的飞片到达预定位置的时刻进行对比。结果表明:多点激光干涉测速系统各测点测得的飞片自由面速度随时间的变化曲线一致,各测点测得的速度最大相对偏差为1.45%;对两套测试系统的零时及信号传输时间进行修正后得到,当飞片飞行至5、10、15 mm位置时,电探针测得的飞片到达时刻与多点激光干涉测速系统测试结果的最大偏差值分别为0.02、0.02、0.07 μs;两套系统在同一测点的测试差值随飞片飞行距离的增加而增加,其原因可能是,炸药透镜的波形差对飞片运动的影响随着飞片飞行距离的增加而增大。 相似文献
9.
激光驱动飞片技术在动高压加载和模拟空间高速粒子运动规律等实验中有重要的应用价值。而激光与飞片的动量耦合模型研究是激光驱动飞片技术的重要内容之一,其实质是激光与物质的作用规律的宏观表征。以激光支持爆轰波(LSDW)理论为基础,建立了约束条件下激光驱动飞片的动量模型,模型考虑了激光功率密度、脉宽、聚焦焦斑、侧向稀疏波、飞片表面气体参数、飞片面积等因素的影响,比较全面地反映了LSDW对飞片的力学作用特性,理论计算结果与参考文献结果吻合较好,误差不超过25%。 相似文献
10.
为了确定磁驱动飞片发射实验结构系数的范围、影响因素、结构系数与影响因素的关系,对聚龙一号装置上的磁驱动飞片发射实验进行了数值模拟和分析。数值模拟表明,磁流体力学程序能正确模拟聚龙一号装置上各个磁驱动飞片发射实验;磁驱动双侧飞片发射实验的结构系数为0.7~0.8;磁驱动单侧飞片发射实验的结构系数为0.80~0.85。磁驱动飞片发射实验的结构系数与实验加载电流无关,仅由磁驱动飞片发射实验的负载结构决定。磁驱动飞片发射实验的结构系数取决于阴阳电极极板的初始宽度、阴阳电极之间的初始间隙以及阴阳电极上飞片厚度之和等三个因素。在磁驱动飞片发射实验中,电极初始宽度、阴阳电极之间的初始间隙不变的情况下,结构系数由阴阳电极上飞片厚度之和确定,阴阳电极上飞片厚度之和越大,结构系数越大。 相似文献
11.
Mark Short Eric K. Anderson Carlos Chiquete Scott I. Jackson 《Proceedings of the Combustion Institute》2021,38(3):3683-3690
We examine the diffraction dynamics of a two-dimensional (2D) detonation in a circular arc of the conventional HMX-based, high performance, solid explosive PBX 9501, for which the detonation reaction zone length scale is estimated to be of the order of 100–150 µm. In this configuration, a steady propagating detonation will develop, sweeping around the arc with constant angular speed. We report on results from three PBX 9501 arc experiments, exploring the variation in linear speed on the inner and outer arc surfaces for the steady wave along with the structure of the curved detonation front, as a function of varying inner surface radius and arc thickness. Comparisons of the properties of the motion of the steady wave for each arc configuration are then made with a spatially-distributed PBX 9501 reactive burn model, calibrated to detonation performance properties in a 2D planar slab geometry. We show that geometry-induced curvature of the detonation near the inner arc surface has a significant effect on the detonation motion even for conventional high explosives. We also examine the detonation driving zone structure for each arc case, and thus the subsonic regions of the flow that determine the influence of the arc geometry on the detonation propagation. In addition, streamline paths and reaction progress isolines are calculated. We conclude that a common approximation for modeling conventional high explosive detonation, wherein the shock-normal detonation speed is assumed equal to the Chapman–Jouguet speed, can lead to significant errors in describing the speed at which the detonation propagates. 相似文献
12.
13.
14.
Jackson Crane Xian Shi Jonathan T. Lipkowicz Andreas M. Kempf Hai Wang 《Proceedings of the Combustion Institute》2021,38(3):3585-3593
A geometric model with a low computational complexity capable of simulating detonation behavior in physical systems is proposed. In support of the geometric model development, a series of cylindrical 1D simulations with a variable size initiation kernel are performed in hydrogen-oxygen mixtures. From these 1D simulations a detonation cell stabilization mechanism is identified. The stabilization mechanism is predicated on the size of the gap between the pressure and temperature fronts at the point where the average pressure front velocity along one cell length is equal to the CJ velocity. This gap, in a multidimensional detonation, is the ignition kernel of a subsequent blast, and dictates the formation of the subsequent cell. Serial analysis of blasts in this context leads to a unique stable blast kernel size for any mixture, which, within the uncertainty of the initial kernel state, can predict the experimental cell length for mixtures considered in this study. Using a tabulation of the 1D simulations as an input, a formulation and sample results of the geometric model are shown. The geometric model can reproduce both qualitative and quantitative features of experimental detonation cellular structure. 相似文献
15.
《Proceedings of the Combustion Institute》2023,39(3):2935-2944
The present work reports new experiments of detonation diffraction in a 2D channel configuration in stoichiometric mixtures of ethylene, ethane, and methane with oxygen as oxidizer. The flow field details are obtained using high-speed schlieren near the critical conditions of diffraction. The critical initial pressure for successful diffraction is reported for the ethylene, ethane and methane mixtures. The flow field details revealed that the lateral portion of the wave results in a zone of quenched ignition. The dynamics of the laterally diffracting shock front are found in good agreement with the recent model developed by Radulescu et al. (Physics of Fluids 2021). The model provides noticeable improvement over the local models using Whitham’s characteristic rule and Wescott, Bdzil and Stewart’s model for weakly curved reactive shocks. These models provide a link between the critical channel height and the critical wave curvature. The critical channel heights and global curvatures are found in very good agreement with the critical curvatures measured independently by Xiao and Radulescu (Combust. Flame 2020) in quasi-steady experiments in exponential horns for three mixtures tested. Furthermore, critical curvature data obtained by others in the literature was found to provide a good prediction of critical diffraction in 2D. These findings suggest that the critical diffraction of unstable detonations may be well predicted by a model based on the maximum curvature of the detonation front, where the latter is to be measured experimentally and account for the role of the cellular structure in the burning mechanism. This finding provides support to the view that models for unstable detonations at a meso-scale larger than the cell size, i.e., hydrodynamic average models, are meaningful. 相似文献
16.
Results of experimental and theoretical studies of the unusual detonation properties of mixtures of high explosives (HEs)
with high-density inert additives (W and Pb) were analyzed and systematized. Typical examples of the nonideal detonation of
composite explosives for which the measured detonation pressure is substantially lower while the detonation velocity is higher
than the values calculated within the framework of the hydrodynamic model, with the specific heat ratio for the detonation
products being ∼6–8, are presented. Mathematical models capable of qualitatively and quantitatively describing the specificity
of the propagation of detonation in HE-W mixtures. Mechanisms of formation of anomalous pressure and mass velocity profiles,
which explain why the correlation between the Chapman-Jouguet pressure for HE-W and HE-Pb mixtures, the velocity of the free
surface of duralumin target, and the depth of the dent imprinted in steel witness plates, are described. 相似文献
17.
Michael Liberman Cheng Wang Chengeng Qian JianNan Liu 《Combustion Theory and Modelling》2019,23(3):467-495
Understanding the mechanisms of explosions is important for minimising devastating hazards. Due to the complexity of real chemistry, a single-step reaction mechanism is usually used for theoretical and numerical studies. The purpose of this study is to look more deeply into the influence of chemistry on detonation initiated by a spontaneous wave. The results of high-resolution simulations performed for one-step models are compared with simulations for detailed chemical models for highly reactive and low reactive mixtures. The calculated induction times for H2/air and for CH4/air are validated against experimental measurements for a wide range of temperatures and pressures. It is found that the requirements in terms of temperature and size of the hot spots, which can produce a spontaneous wave capable to initiate detonation, are quantitatively and qualitatively different for one-step models compared to detailed chemical models. The time and locations when the exothermic reaction affects the coupling between the pressure wave and spontaneous wave are considerably different for a one-step and detailed models. The temperature gradients capable to produce detonation and the corresponding size of hot spots are much shallower and, correspondingly, larger than those predicted using one-step models. The impact of the detailed chemical model is particularly pronounced for the methane-air mixture. In this case, not only the hot spot size is much greater than that predicted by a one-step model, but even at the elevated pressure, the initiation of detonation by a temperature gradient is possible only if the temperature outside the gradient is rather high, so that can ignite a thermal explosion. The obtained results suggest that the one-step models do not reproduce correctly the transient and ignition processes, so that interpretation of the simulations performed using a one-step model for understanding mechanisms of flame acceleration, DDT and the origin of explosions must be considered with great caution. 相似文献
18.
19.
SUI GuoFa LI JinShan SUN Feng* MA Bei & LI HongWei State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi’an China 《中国科学:物理学 力学 天文学(英文版)》2011,(5)
A 3D finite element model of the explosive welding process of three-layer plates with materials of steel-copper-copper is established. Based on the presented model, the bonding mechanism is simulated and analyzed, different detonation modes are also comparatively studied to indicate the driving force spread in few microseconds. The results show that the three layer plates bond together after many times of impact between the flyers and the base driven by detonation wave, which is damping rapidly at each impa... 相似文献