统一二阶矩模型用于模拟旋流湍流两相流动

用统一二阶矩模型（ＵＳＭ）模拟了旋流数为０４７和１５的气粒两相流动，并和实验结果以及ｋ ε ｋｐ模型的模拟结果进行了对比．研究结果表明，提高旋流数减小了轴向速度反流区，增大了切向速度似固核区．ＵＳＭ和ｋ ε ｋｐ模型预报旋流数为０４７时的两相速度场差别不大，并都和实验结果接近，但前者预报的旋流数为１５的两相速度场比后者有改进，在两种情况下，前者都能揭示出后者无法预报的两相湍流各向异性规律．     

微重力下密闭腔体内火焰传播过程的数值模拟

建立了微重力条件下火焰沿固体可燃物表面蔓延的数学模型．在考虑固相传热和热解过程的基础上，研究气相的燃烧动力学过程，并且给出了体现微重力燃烧两相耦合作用的相界面处理方法．首次用数值模拟的方法研究了密闭腔体内火焰传播的三维非稳态过程，对于微重力大小分别为１０－４ｇ和１０－２ｇ时的计算结果进行了分析对比．数值模拟的结果基本合理．     

洗衣机液体平衡环仿真模拟

波轮式洗衣机在脱水过程中会因离心力而产生强烈的振动，液体平衡环的纠偏特性是减振的最主要方式之一．平衡环通过环内液体流动产生的离心力来达到减振目的，因此平衡环内液体离心力数值的准确性直接影响仿真模拟的结果．过往研究采用离心力理论公式进行的仿真模拟与实验结果有较大偏差．而本文将FLUENT仿真得到的离心力数值，代入ADAMS中进行洗衣机整机的仿真，可以得到与实验更为接近的仿真结果．     

洗衣机液体平衡环偏心旋转研究

洗衣机在旋转过程中会产生较大离心力,由于偏心旋转,引起内筒与壁面的强烈撞击．为了减小撞击引起的振动,洗衣机上安装液体平衡环．平衡环结构的设计,包括平衡环环道的数量、平衡环内部腔体的数量、隔断上面开孔的位置和大小、注入液体体积等．对五种结构的平衡环进行了数值模拟分析,包括单环无腔平衡环、双环无腔平衡环、单环3腔平衡环、双环3腔平衡环和双环24腔平衡环;研究了3 mm、5 mm的不同偏心距以及25rpm、30rpm、40rpm、50rpm等不同转速和平衡环启动阶段0~15s的动态转速等旋转条件的影响．本文首先对平衡环偏心旋转离心力的现有理论计算模型进行改进,然后,通过四种平衡环、四种转速、两种偏心距下的离心力数值模拟,验证了所做改进的合理性和有效性,最后,对三种平衡环、两种偏心距进行启动阶段的动态数值模拟,并对模拟结果进行分析,从而给出平衡环结构上的设计建议．     

基于格子Boltzmann两相模型的粘弹流体挤出胀大分析

挤出胀大的数值模拟是非牛顿流体研究中具有挑战性的问题．本文运用格子Boltzmann方法(LBM)分析Oldroyd-B和多阶松弛谱PTT粘弹流体的挤出胀大现象，采用颜色模型模拟出口处粘弹流体和空气的两相流动，通过重新标色获得两种流体的界面，并最终获得胀大的形状．Navier-Stokes方程和本构方程的求解采用双分布函数模型．将胀大的结果与解析解、实验解和单相自由面LBM结果进行了比较，发现格子Boltzmann两相模型结果与解析解和实验结果相吻合，相比于单相模型，收敛速度更快，解的稳定性更高．研究了流道尺寸对胀大率的影响，并对挤出胀大的内在机理进行了分析．     

液态铝在多孔介质中低压渗流过程的模拟实验研究

本文根据相似原理对液态铝在多孔介质中的低压向上渗流过程进行了模拟试验研究，试验表明，渗流液面以平面沿垂方向推进，位移－时间关系符合四次方根规律；某一时刻Ｔ的雷诺数，阻力系数和沿程损失可用相应的公式计算外加渗流气压的最佳值为０．４０ａｔ．。实验还将模拟充填时间与原型充填时间进行了对比，两者得到了良好的一致性。     

环空后台阶管道内气固两相流动的数值模拟研究

环空管道后台阶突扩流动是空气正循环钻井过程中十分重要的关键部分,直接决定了钻探岩屑是否能够顺利上返地面.本文采用Euler-Lagrange两相流研究方法,气相湍流采用Realizable k-ε模型,固相采用离散相模型(DPM),固相的湍流耗散采用随机轨道模型,对环空后台阶突扩管道内气固两相流动进行了数值模拟研究.得出了气相场大涡演变规律,在此基础上研究了不同粒径时颗粒在流道中的浓度分布规律、运动轨迹,以及速度场分布规律.这为细观框架下研究气固两相相互作用规律提供了依据.     

固体、流体多相孔隙介质中的波动理论及其数值模拟的进展

简要回顾了两相或三相多孔介质中波动理论和数值模拟的研究历史和现状，着重介绍了用有限元方法对饱水土层中波动进行数值模拟的研究进展，并讨论了有待进一步研究的问题．     

油滴在液-液旋流分离中的随机轨道数值模拟

在不考虑相间相互作用的条件下，对水相采用DSM湍流模型，油相采用随机轨道模型，成功地模拟了两组不同粒径的油滴群在两种典型液一液旋流分离管中的运动轨迹，较好地揭示了不同粒径油滴在旋流管中的分离过程．通过比较可知油滴在优选结构旋流管中的捕集过程明显比F型旋流管中快，有关结果与对该两种旋流管的分离特性研究结果相吻合，由此说明了优选结构旋流管具有更好的分离作用．     

气液两相涡街的数值计算

本文利用有限差分法，建立了模拟气液两相涡街的物理模型和数值计算方法，成功地利用数值方法模拟出了气液两相涡街及涡街中含气率分布等主要特征，该方法简便，理论计算出的结果与实验值相符较好     

GENERAL SOLUTION OF THE OVERALL BENDING OF FLEXIBLE CIRCULAR RING SHELLS WITH MODERATELY SLENDER RATIO AND APPLICATIONS TO THE BELLOWS (Ⅳ)-CALCULATION FOR U-SHAPED BELLOWS

ＩｎｔｒｏｄｕｃｔｉｏｎＵ＿ｓｈａｐｅｄｂｅｌｌｏｗｓａｒｅｕｓｕａｌｌｙｓｅｅｎｉｎｔｈｅｐｉｐｅｌｉｎｅｓｙｓｔｅｍ (Ｆｉｇ .1) ,ｗｈｉｃｈａｒｅｕｓｅｄｔｏｃｏｍｐｅｎｓａｔｅｆｏｒｔｈｅａｘｉａｌｍｏｖｅｍｅｎｔ,ｔｈｅｒｏｔａｔｉｏｎａｎｄｔｈｅｄｅｆｌｅｃｔｉｏｎｏｆｔｈｅｐｉｐｅｌｉｎｅｓｄｕｅｔｏｔｈｅｔｈｅｒｍａｌａｃｔｉｏｎ ,ｔｈｅｂａｓｅｕｎｅｑｕａｌｓｅｔｔｌｅｍｅｎｔｓａｎｄｔｈｅｉｎｓｔａｌｌａｔｉｏｎｅｒｒｏｒｓ.Ｔｈｅａｘｉｓｙｍｍｅｔｒｉｃａｌｄｅｆｏｒｍａｔｉｏ…     

Shaped charge with an axial channel

A shaped charge with an axial channel is considered. The charge is initiated by an impact of an annular plate. As a result, the shaped charge is initiated at all points of the domain shaped as a ring. The impact plate material and parameters (velocity, thickness, width, and distance covered by the plate) that ensure stable penetration of the shaped charge are determined. The results obtained can be used to develop a composite (e.g., “tandem”) shaped charge of the “base-head” type (the charge located farther from the target is first initiated, followed by initiation of the charge located closer to the target).     

Experimental study of toroidal shock wave focusing in a compact vertical annular diaphragmless shock tube

The paper reports results of experiments regarding toroidal shock wave focusing in a vertical shock tube as a part of a series of converging shock wave studies. This compact vertical shock tube was designed to achieve a high degree of reproducibility with minimum shock formation distance by adopting a diaphragmless operating system. The shock tube was manufactured in the Institute of Fluid Science, Tohoku University. An aspheric lens shaped cylindrical test section was connected at the open end of the shock tube to visualize the diffraction and focusing of the toroidal shock wave released from the ring shaped shock tube opening. Pressure transducers were flush mounted on the shock tube’s test section to measure pressure histories at the converging test section. Double exposure holographic interferometry was employed to quantitatively visualize the shock waves. The whole sequence of toroidal shock wave diffraction, focusing, and its reflection from the symmetrical axis were successfully studied. The transition of reflected shock waves was observed.     

On the sign of the internal stresses in a problem of plane elasticity

An elastic plane body, shaped like a circular ring or a disk, is subjected to radial surface forces varying according to a sinusoidal law. The existence of a tensile region included in a purely compressive one is proven and its asymptotic behaviour studied when the surface forces converge to two concentrated loads acting along the same diameter. The results show that any maximum principle for the principal stress components would require conditions stronger than the simple negativity of both on the boundary of the domain.     

夹层聚能装药作用过程的数值模拟

基于凝聚炸药冲击起爆的Lee-Tarver模型,利用AUTODYN有限元计算软件对夹层聚能装药作用过程进行了数值模拟。分别对夹层聚能装药爆轰波形传播过程及其特性参数进行了数值计算,对典型聚能装药采用单一结构装药、夹层装药的射流成型过程进行了数值研究,最后对不同爆速炸药匹配关系的夹层聚能装药射流参数进行了计算分析。计算结果表明,相对于单一结构装药,夹层装药射流头部速度提高了20%,夹层聚能装药能有效提高聚能金属射流头部速度、提高侵彻深度、增加炸药装药的作功能力。     

Organizational Modes of Large-Scale Vortices in an Axisymmetric Turbulent Jet

Large vortices occurring in the axial plane of a self-similar axisymmetric turbulent jet are educed by spatially filtering PIV data. First, the instantaneous PIV frame is convolved with a Gaussian kernel to obtain a smooth (low-pass) field. Next, the low-pass field is Galilean transformed to expose the large vortices residing near the edges of the jet. Large vortices tend to organize themselves in preferred modes; evidence of ring and helical modes is revealed by Galilean transformation of the low-pass filtered field. Both modes seem to occur prominently in jets, with the helical mode being the more frequent. The overall diameter of both ring and helical modes is comparable with the local jet width. The low-pass field occasionally exhibits arrowhead shaped structures with large entrainment at their downstream tips. Stochastic estimates computed from the Galilean-transformed low-pass filtered field indicate that jet meander and a sweep-in of ambient fluid are sufficient to reconstruct large vortices. The frequency of occurrence of modes agrees with previously quoted results. This revised version was published online in July 2006 with corrections to the Cover Date.     

Jet formation and penetration mechanism of W typed shaped charge

Existing classical shaped charges are well known for their longer jets capable of achieving large hole depth to hole diameter ratios in metallic targets. However, in some situations, there arises demand to obtain 1：1 ratio for hole depth to hole diameter which is beyond normal shaped charges capability. A new variant of shape charge, named W typed shape charge （WSC）, is proposed in this paper, which can meet the demand of 1：1 ratio, and is based on the geometry that can produce annular jets upon proper initiation scheme. In this paper, we present formation and penetration results of WSC based on three different schemes. We also show that not all WSC designs can form annular jets, only annularly initiated WSC, which also fulfils the ＂Internal-External Liners Equal-Impulse＂ criterion, has the capability to form annular jet. The experimental and numerical results show that when the ratio between annular initiation ring diameter and the charge diameter is 0.75, an annular jet is formed, which was also supported by high speed photographs performed in vacuum. 2D numerical simulations are performed with indigenously developed simulation software, where Eulerian approach with multi-material interface tracking algorithm is utilized, to find various mechanisms involved during jet formation process. The calculation results are found in good agreement with the experimental results, indicating that the interface treatment algorithm proposed in this paper can not only deal with large deformation problem, but also depict clearly the variation of materials interface. It is especially suitable for simulation of the process from liner collapse to formation of shaped charge jet.     

聚能装药对混凝土靶板的侵彻研究

系统开展了不同药型罩材料、不同锥角、不同壁厚的聚能装药在不同炸高下侵彻混凝土试验, 研究了罩材料、锥角、壁厚、炸高等结构参数对漏斗坑直径、侵彻孔洞直径、漏斗坑深度以及侵彻深度等参数的影响规律;应用空腔膨胀理论计算了混凝土靶体阻力, 采用改进的伯努利方程和两阶段空腔膨胀理论获得了混凝土靶板在侵彻体作用下的侵彻深度和孔洞直径, 理论结果与试验结果基本吻合;基于AUTODYN 软件平台, 采用与试验一致的聚能装药结构, 开展了57 种工况下侵彻体成形过程的数值模拟研究, 并对其中典型工况的侵彻混凝土过程进行了数值模拟, 计算所得孔洞直径和侵彻深度与试验结果吻合较好, 在此基础上深入探讨了聚能装药作用下混凝土漏斗坑的形成机理, 分析表明, 铝药型罩的开坑机理不同于钢和铜药型罩.      

一种新型聚能破甲弹的应用研究

基于能量利用的观点提出一种新型聚能破甲弹装药结构，对其破甲性能进行研究；在进行射流与弹丸的成型过程和破甲机理理论分析基础上，采用静破甲实验对该破甲弹装药结构的关键参数和大、小锥角聚能罩材料之间匹配关系对破甲效果影响进行了系统研究．实验结果表明：在各自最佳炸高条件下，该新型聚能装药结构比EFP装药结构，在保持相当穿孔孔径、同等装药和壳体约束条件下，可以提高穿深达50％左右；进一步深化和丰富了聚能效应内涵．     

反钢筋混凝土串联聚能装药技术研究

根据钢筋混凝土目标的特点,提出了一种高速杆流与低速杆流相结合的新型串联聚能装药结构。利用有限元软件分别对前级装药、后级装药的成型过程进行了数值仿真。在此基础上开展了系列串联聚能装药毁伤钢筋混凝土目标的静破甲实验。结果表明:该串联装药可有效提高对钢筋混凝土目标的毁伤能力,能起到对钢筋混凝土的扩孔作用。实验和数值仿真计算结果都表明该串联装药在对付钢筋混凝土、机场跑道、多层间隔靶等反硬目标串联型战斗部中有较好的应用前景。