共查询到17条相似文献,搜索用时 109 毫秒
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高强度冲击加载作用下金属材料的动态物理行为是当前冲击波领域基础研究和工程应用最为关注的焦点。采用光滑粒子法(SPH)开展不同位置起爆诱发的斜冲击波对碰加载金属铅的二维数值模拟研究,得到了金属铅内入射斜冲击波的角度和强度,并利用极曲线方法理论上导出发生马赫反射时的临界入射角和入射马赫数关系。根据计算结果可知,金属铅内入射斜波对碰后将发生马赫反射。随着起爆位置与金属铅表面距离的增加,不仅金属铅内入射冲击波强度和入射角增加,而且形成的马赫杆宽度也在增加。由自由面速度剖面给出了马赫杆宽度及张角,结果与理论预测的结果吻合较好。 相似文献
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结合实验和数值模拟,研究了散心冲击波在金属柱壳约束下沿有机玻璃内部的空间分布。进行了点起爆柱状炸药驱动飞片加载实验,采用Polyvinylidence Fluoride (PVDF)测试方法对有机玻璃内部的压力进行测试。实验结果显示:在冲击波传播过程中,在特定传播距离处,离中心轴越近,冲击波第一幅值压力越小,这是因为散心冲击驱动飞片成前凸形状,在飞片飞行过程中与有机玻璃碰撞面积越来越大,在远离对称轴部位冲击压力叠加累积效应更强引起的;但在随后的冲击波传播过程中,由于受到柱壳约束影响,离对称轴越近,冲击波幅值越小,这是由散心冲击波在约束柱壳边界反射与冲击波波阵面叠加的结果。通过对炸药网格大变形溢出柱壳翻转进行合理处理,对实验进行了数值模拟。数值模拟结果所得的冲击压力沿径向分布规律计算结果与实验结果定性相符。最后探讨了不同约束程度对这一规律的影响程度,结果表明,后续的冲击波幅值随着约束的增加而急剧增加。 相似文献
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为研究爆炸冲击波对钢化玻璃的毁伤阈值,开展了钢化玻璃冲击波毁伤效应实验。对每一发实验进行了爆炸参数测试,获得了冲击波超压随时间变化历程的实验数据。通过对实验数据的处理与分析,得到了爆炸冲击波基本参数,包括正反射超压、冲击波到时、正压作用时间、正反射冲量、负反射超压、负压作用时间和负反射冲量等。将实验结果与CONWEP计算结果进行了比较,比较结果表明二者误差很小,证明冲击波测试结果准确可靠。对冲击波正负反射参数进行了比较,结果表明冲击波正反射参数明显高于冲击波负反射参数。 相似文献
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本文分析了空气冲击波与运动刚壁的相互作用,给出了运动刚壁正反射或斜反射时壁面峰值反射超压的计算公式。当刚壁速度为零时,这些公式退化成空气冲击波遇固壁相互作用的计算公式。 相似文献
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本文讨论了真实空气中冲击波的正反射和正规反射,并用H.L.Brade拟合的空气状态方程进行了计算。计算结果表明,当入射冲击波超压小于约20大气压时,反射冲击波的超压值和动压值实际上和理想气体计算结果一致,当入射冲击波较强时,则反射冲击波参数比理想气体结果显著增大。 相似文献
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The head-on collision of a planar shock wave with a dust-air suspension is studied numerically. In this study the suspension
is placed inside a conduit adjacent to its rigid end-wall. It is shown that as a result of this collision two different types
of transmitted shock waves are possible, depending on the strength of the incident shock wave and the dust loading ratio in
the suspension. One possibility is a partially dispersed shock wave, the other is a compression wave. The flow fields resulting
in these two options are investigated. It is shown that in both cases, at late times after the head-on reflection of the transmitted
shock wave from the conduit end-wall a negative flow (away from the end-wall) is evident. The observed flow behavior may suggest
a kind of dust particle lifting mechanism that could shed new light on the complex phenomenon of dust entrainment behind sliding
shock waves.
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相比气体,固体介质在高压下的状态方程更为复杂,形式也多种多样.现有关于固体介质中激波反射的理论研究,一般直接采用某种状态方程,缺乏对采用不同状态方程得到的结果的对比.本项工作采用激波极曲线的理论分析方法,选择4种不同组合形式的状态方程(一次冲击激波采用线性的冲击波速度与粒子速度关系式,二次冲击激波采用Gr(u|¨)neisen状态方程;一次冲击和二次冲击激波均采用冲击波速度与粒子速度关系式:一次冲击激波采用线性冲击波速度与粒子速度关系式,二次冲击激波采用刚性气体状态方程;以及一次冲击激波和二次冲击激波均采用刚性气体状态方程),研究固体介质中的斜激波反射,比较了采用不同组合形式的状态方程对反射激波波后压力的影响.利用量纲分析方法讨论了简化状态方程达到较高精度的条件.此外,用ANSYS/LS-DYNA软件,对激波极曲线理论给出的结果进行了验证.本项工作可为固体介质中激波反射问题状态方程的选取提供一定的指导. 相似文献
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The collision of two blast waves is analyzed for the case of variable parameters of the gas behind the wave front and wave reflection at a plane, a cylindrical, and a spherical obstacle. The reflection of a blast wave from a nonmoving obstacle is investigated in detail. The problem of the collision of two shock waves with constant parameters behind the front is solved both in the symmetrical case (reflection from a nonmoving wall) and in the case of waves of different amplitudes by a system of algebraic relations for the compression shocks. The reflection of a strong point-source spherical shock wave from a wall has been treated in [1, 2]. The present article examines the initial stage of wave collision for an arbitrary distribution of the parameters behind the front.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 41–48, September–October, 1971.The authors are grateful to V. P. Korobeinikov for a discussion of the results and to V. P. Kolgan for furnishing the numerical solutions. 相似文献
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Regular reflection (RR) and Mach reflection (MR) are theoretically both possible in the dual-solution domain of oblique shock reflection. The physical difference between the two types of reflection is the pressure behind the reflected shock wave: that of MR is lower than that of RR for strong shock reflection. The magnitude relation of these pressures is inverted for weak shock reflection. In the present paper, we performed two kinds of experiment, depending on whether the oblique shock reflection is weak or strong. For strong shock reflection, we decreased the pressure behind the reflected wave of RR using a convex double-wedge. For weak shock reflection, we increased this pressure using a concave double-wedge. Thus, we investigated the stability of RR against pressure disturbances. The results indicate that RR in a shock tube is stable, in the dual-solution domain, for both weak and strong incident shocks. 相似文献
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In the present paper, the water wave diffraction by a two-dimensional floating elastic plate is analyzed in the presence of compressive force. The solutions in the cases of infinite and finite water depths are derived based on integro-differential equation method in the presence of compressive force under the assumption of small amplitude water wave theory and plate deflection. Further, wave diffraction by the floating elastic plate is analyzed under the assumption of shallow water approximation. The role of compressive force and its limiting values are obtained by using the hydroelastic analysis of the flexural gravity waves. The limiting values of oblique angle of incidence are obtained in different cases and the effect of compressive force on the oblique angle is analyzed. Effect of compressive force and angle of incidence on the hydroelastic behavior of the floating plate are studied by analyzing the reflection coefficients in different cases. 相似文献
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A holographic interferometric study was made of the focusing of reflected shock waves from a circular reflector. A diaphragmless
shock tube was used for incident shock Mach numbers ranging from 1.03 to 1.74. Hence, the process of reflected shock wave
focusing was quantitatively observed. It is found that a converging shock wave along the curved wall undergoes an unsteady
evolution of mach reflection and its focusing is, therefore, subject to the evolution of the process of shock wave reflections.
The collision of triple points terminates the focusing process at the geometrical focus. In order to interprete quantitatively
these interferograms, a numerical simulation using an Eulerian solver combined with adaptive unstructured grids was carried
out. It is found numerically that the highest density appears immediately after the triple point collision. This implies that
the final stage of focusing is mainly determined by the interaction between shock waves and vortices. The interaction of finite
strength shock waves, hence, prevents a curved shock wave from creating the infinite increase of density or pressure at a
focal point which is otherwise predicted by the linear acoustic theory. 相似文献
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Numerous authors have carried out rather extensive studies in the last twenty to thirty years of the problem of the interaction of shock and blast waves with obstacles in their paths. Owing to the complexity of the problem, they assumed certain limiting cases for the shock wave interactions in which the parameters behind the shock wave were usually taken to be constants. The first wave diffraction studies involving variable parameters behind the front were presented in [1, 2], wherein a development of the theory of “short waves” (blast waves at a substantial distance from the center of an explosion) and their reflection from a planar surface was given. The theory of short waves assumes that the jump in pressure at the wave front and the region over which the parameters vary are small. The problem concerning reflection of a blast wave from a surface was also considered in [3, 4], wherein a solution in the region behind the reflected wave was obtained at initial times. The initial stage in the reflection of a blast wave from a planar, cylindrical, or spherical surface (the one-dimensional case) was studied in [5]. In this paper we investigate the interaction of a spherical blast wave, resulting from a point explosion, with a planar surface; we consider both regular and non-regular reflection stages. In solving this problem we use S. L. Godunov's finite-difference method. We obtain numerical solutions for various values of the shock strength at the instant of its encounter with the surface. We present the pressure fields in the flow regions, the pressure distribution over the surface at various instants of time, and the trajectories of the triple point. The parameter values at the front of the reflected wave are compared with results obtained from the theory of regular reflection of shock waves. 相似文献