共查询到19条相似文献,搜索用时 515 毫秒
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从静/动态空腔膨胀模型的理论体系出发,介绍了空腔膨胀模型在不同方向上取得的成果,主要涉及理想侵彻条件的空腔膨胀压力计算模型及数值模拟方法和空腔膨胀模型在典型侵彻问题及复杂弹靶条件下的应用。在理想侵彻条件下的空腔膨胀压力计算模型中,主要讨论了靶体材料、屈服准则和状态方程对空腔边界应力的影响规律及空腔膨胀模型的适用性问题;根据数值模拟中初始条件的不同,介绍了空腔表面恒定速度/恒定压力两种数值模拟方法,证明了数值模拟方法的可靠性;整理了空腔膨胀模型的基本假设、适用范围、工程应用特点,列举了其在典型侵彻问题及多层复合靶板、约束靶体、弹体刻槽和异形截面形状弹体等复杂弹靶条件下的应用。针对空腔膨胀模型的研究现状,总结了目前空腔膨胀模型在冲击动力学领域的应用方向,归纳了空腔膨胀模型应用中尚存在的问题,展望了空腔膨胀模型下一步的重点发展方向。 相似文献
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Stokes流问题中的辛本征解方法 总被引:8,自引:0,他引:8
通过引入哈密顿体系,将二维Stokes流问题归结为哈密顿体系下的本
征值和本征解问题. 利用辛本征解空间的完备性,建立一套封闭的求解问题方法. 研究结果
表明零本征值本征解描述了基本的流动,而非零本征值本征解则显示着端部效应影响特点.
数值算例给出了辛本征值和本征解的一些规律和具体例子. 这些数值例子说明了端部非规则
流动的衰减规律. 为研究其它问题提供了一条路径. 相似文献
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蒙特卡罗直接模拟(Direct Simulation Monte-Carlo)方法是一种基于分子动力论的随机性数值模拟方法,它在各类稀薄气体流动模拟中得到了广泛应用。本文首先讨论了DSMC方法的基本原理,引用文献结果论述了DSMC方法与Boltzmann方程的内在一致性,采用DSMC方法从分子运动论层次对过渡区开式空腔流动进行精细模拟,再现空腔内旋涡的形成及发展过程,了解复杂流场的流场特性。模拟和分析了空腔的形状(展弦比)、壁温以及Knudsen数(稀薄性)等因素对空腔内流动和旋涡结构的影响。研究表明,空腔的展弦比、壁面温度以及流动Knudsen数等因素对空腔内旋涡的大小、形状、位置、个数都有极大的影响,应用DSMC方法可以真实再现稀薄条件下的开式空腔流动。 相似文献
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为提高金属靶的抗弹性能,设计了一种含有月牙形空腔结构的金属靶。利用ABAQUS软件对月牙形空腔结构在12.7 mm穿甲燃烧弹弹芯侵彻下的弹体偏转性能进行了数值模拟研究,讨论了月牙形状、弹着点和空间排布对弹体偏转效果的影响。结果表明:月牙形状对弹体的偏转效果有显著的影响;空腔结构在不同弹着点表现出不同的弹体偏转性能,处于空腔胞元最薄弱处附近的弹着点弹体偏转角度明显小于其他位置;空腔胞元空间排布的非对称化处理能够提升空腔结构对子弹的偏转效果。 相似文献
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爆轰载荷作用下球形空腔的动力响应 总被引:7,自引:1,他引:7
以位移为未知量,利用拉普拉斯变换法,研究了球形空腔在爆轰载荷作用下的动力响应问题,获得了问题的参数解,并通过直接代入,验证了解的正确性。 相似文献
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采用二维大涡模拟方法进行了空腔水流场的数值计算, 考察空腔前缘动量损失厚度及来流速度等因素如何影响空腔流的振荡, 同时考察了空腔长深比与空腔流振荡模式的关系. 用空腔水流场的粒子图像测速测量结果验证了数值计算的可信性.结果表明, 空腔水流是否发生振荡取决于壁面摩擦速度.瞬时涡结构和空腔阻力系数2个方面的特征显示空腔水流场有2种典型的振荡模式, 剪切层模式与尾流模式, 确定振荡模式的关键因素是空腔长深比. 相似文献
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Symplectic solution system for reissner plate bending 总被引:3,自引:0,他引:3
Based on the Hellinger-Reissner variatonal principle for Reissner plate bendingand introducing dual variables, Hamiltonian dual equations for Reissner plate bending werepresented. Therefore Hamiltonian solution system can also be applied to Reissner platebending problem, and the transformation from Euclidian space to symplectic space and fromLagrangian system to Hamiltonian system was realized. So in the symplectic space whichconsists of the original variables and their dual variables, the problem can be solved viaeffective mathematical physics methods such as the method of separation of variables andeigenfunction-vector expansion. All the eigensolutions and Jordan canonical formeigensolutions for zero eigenvalue of the Hamiltonian operator matrix are solved in detail, and their physical meanings are showed clearly. The adjoint symplectic orthonormal relation of the eigenfunction vectors for zero eigenvalue are formed. It is showed that the alleigensolutions for zero eigenvalue are basic solutions of the Saint-Venant problem and theyform a perfect symplectic subspace for zero eigenvalue. And the eigensolutions for nonzeroeigenvalue are covered by the Saint-Venant theorem. The symplectic solution method is notthe same as the classical semi-inverse method and breaks through the limit of the traditional semi-inverse solution. The symplectic solution method will have vast application. 相似文献
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In this paper,a new analytical method of symplectic system.Hamiltonian system,is introduced for solving the problem of the Stokes flow in a two-dimensional rectangular domain.In the system,the fundamental problem is reduced to all eigenvalue and eigensolution problem.The solution and boundary conditions call be expanded by eigensolutions using ad.ioint relationships of the symplectic ortho-normalization between the eigensolutions.A closed method of the symplectic eigensolution is presented based on completeness of the symplectic eigensolution space.The results show that fundamental flows can be described by zero eigenvalue eigensolutions,and local effects by nonzero eigenvalue eigensolutions.Numerical examples give various flows in a rectangular domain and show effectivenees of the method for solving a variety of problems.Meanwhile.the method can be used in solving other problems. 相似文献
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In this paper, a new analytical method of symplectic system, Hamiltonian system, is introduced for solving the problem of the Stokes flow in a two-dimensional rectangular domain. In the system, the fundamental problem is reduced to an eigenvalue and eigensolution problem. The solution and boundary conditions can be expanded by eigensolutions using adjoint relationships of the symplectic ortho-normalization between the eigensolutions. A closed method of the symplectic eigensolution is presented based on completeness of the symplectic eigensolution space. The results show that fundamental flows can be described by zero eigenvalue eigensolutions, and local effects by nonzero eigenvalue eigensolutions. Numerical examples give various flows in a rectangular domain and show effectiveness of the method for solving a variety of problems. Meanwhile, the method can be used in solving other problems. 相似文献
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用状态向量法,引出陀螺线性系统的广义本征问题,证明了本征向量之间的加权共轭辛正交关系,以及用本征向量对任意状态向量的展开定理。运用反对称矩阵胞块组成的LDL~T分解,将本征方程导向辛本征问题的标准型。这套方法适用于陀螺系统K阵不正定的情形。对于辛本征问题用SH变换将矩阵化为半边三对角线胞块阵或三对角线胞块阵,然后再求解其全部本征解。为陀螺系统的模态分析打下了基础。 相似文献