数值分析

In this paper, the numerical simulation and experimental studies have been performed in order to understand the characteristics of the turbulent jets in crossflow, and the result is analyzed.

本文分别对缝隙和圆孔横向紊动射流的流场进行了数值模拟和实验分析，系统地分析了横向紊动射流的流场结构和流动机理。

In this thesis, the engineering property of the frozen earth in the frozen railway roadbed in Anduo section (between DK1561+975-DK1562+530) of Naquhe region of Qinghai-Tibet railway was studied indoor. The change of engineering property of the earth samples with different water content , density and temperature were researched. The influence of concentration of the diffluent salt to the frozen strength was pilot studied. The thermal conductivity of the soil was experimented. With the result and data of the tests, the earth temperature field in Anduo section was demonstrated by numerical analysis, the structure parameter of the spall revetmentd and the rubble berm was given, the stability of the railway roadbed was evaluated.

本文以青藏铁路格尔木-拉萨段那曲河地区安多段(DK1561+975～DK1562+530)冻土路基为对象，对该地区冻土的工程性质进行了室内试验研究；对不同含水率、不同压实度的土样，研究在特定温度变化范围内工程性质的变化：初步分析了易溶盐含量对冻结强度的影响：测试了土样的导热系数；在室内土工试验的基础上，根据测试结果和数据，对安多段区域地温场进行了数值模拟，分析了该工点区间内合理片石护道、碎石护坡结构参数，评价了路基稳定性。

Incurrent research, aiming at the rupture problem engendered in the shooting process of acertain 5.56mm automatic rifle, the strain and stress distributions on the cartridge caseunder the action of axial pull have been analyzed. Based on the theories of elastic-plasticmechanics and contact mechanics, a mathematic and physical model of the cartridge-caseand chamber system has been set up; and based on the platform of the general softwarepackage APDL of ANSYS for finite element analysis, a parameterized model of thecartridge-case and chamber system has also been established. The method for nonlinearFEA has been adopted to analyze the stress distribution on the entire cartridge-case andchamber system, and the method of contact element has been employed to investigate thecontact stress between the cartridge case and chamber, and then the influences of frictioncoefficient and locking space on the static and dynamic stress and strain response of thecartridge case and chamber to the action of power gas have also been discussed. On thebasis of a lot of numerical tests, a kind of element Plane13, which is concentrated incoupled computation of heat and construction, has been used finally to simulate thetransient response of the cartridge-case and chamber system to the power gas. Throughloading the temporary thermal characteristics of explosive gas in the procedure of emulate, the corresponding transient thermal stress distributed on the entire system under thecombined load of transient thermal stress and transient pressure has been obtained. Owingto these comprehensive considerations, the numerical results obtained in this paperrepresent the actual situations comparatively exactly.

本文针对某5.56mm自动步枪在工作中出现断壳的问题，分析了弹壳在轴向拉力作用下的应力应变；基于弹塑性力学及接触理论，建立了弹壳弹膛系统的数学、物理学模型，在通用有限元ANSYS软件的参数化建模工具APDL平台上，建立了弹壳弹膛系统的参数化模型；采用非线性有限元法计算了弹壳弹膛系统的整体应力，引入接触单元法分析弹壳和弹膛的接触压力，探讨了在不同的摩擦系数和不同的闭锁间隙对弹壳弹膛静、动态响应的影响；本文进行了大量的尝试，最后确定采用热、结构耦合单元Plane13，在计算中加载了火药气体的温度历程，成功的获得了弹壳弹膛系统在瞬态的热载荷和瞬态的压力载荷同时作用下弹壳弹膛系统的热应力数值解，考虑因素全面，比较真实的反映了弹壳弹膛系统在火药气体压力和热载荷下作用的情况。

The mathematical models of screed unit as well as hydraulic system parts are systematically answered, including the calculation of kinetical model based on hypothesis factors and dynamical model in consideration of forces acting on the screed.

在分析液压部件环节数学模型的基础上，首次系统地推导了熨平机构环节的运动学模型和动力学模型，并对系统的数值计算结果和实验结果作了对比分析。

Based on the analysis of kinetical process of CH4 -air oxidation, a numerical modeling of the species concentrations and temperature for CH4 jet diffusion combustion is made using a four-step reduced mechanism and two semi-detailed chemical kinetical reaction mechanismsW mechanism and Y mechansim.

在分析甲烷-空气氧化反应动力学过程的基础上，采用四步简化机理和两种半详细的化学反应动力学机理-W机理和Y机理，对甲烷射流扩散燃烧的组分浓度和温度进行了数值模拟，计算结果与实验结果进行了对比分析。

The high frequency combustion instability in liquid rocket engine LRE is analyti cally studied by usin g CFD methods.The comprehensive model and governing equations for numerical simu lation of high frequency combustion instability are presented.The PISO and MacCo rmack algorithms are compared in this study.Both methods can successfully handle combustion instability analysis.

应用CFD方法对液体火箭发动机中的高频燃烧不稳定性进行了分析研究，建立了液体火箭发动机不稳定燃烧数值模拟的综合模型和控制方程，比较了PISO和Ma cCormack两种算法，得出了两种算法均能成功应用于不稳定燃烧分析的结论。

For some rock slopes, which have not distinct failure surface, but have complicated structure or load on the top and so on, a stability analysis of this type slopes by finite element method is presented, the failure surface is defined by certain rule or strain zone from the computed model, and then the safety factor of the rock slope is abtained by finite element method and limit equilibrium methodAt last, using ANSYS , a famous commercial finite element analysis software, a example of high-steep slope which is bearing the load of the LongGe Mansion is presented, the stability of this slope is studied, as a paradign the the stability evalution of complicated high-steep slope under the action of load of building , the chapter gives some meritable reference in stability assessment of rock slopes using numerical simulation by three-dimension elastic-plastic finite element.

并用有限单元法建立边坡的具体模型，应用折减边坡岩体参数、逐级施加荷载等与边坡工作环境相似的方法进行模拟计算，根据计算结果，采用一定的判别准则或图形可视化方法，确定出边坡的滑裂面，再采用刚体极限平衡法或有限单元法计算其安全系数；最后，通过某一工程实例，用大型有限元程序对边坡在建筑物荷载作用下的稳定性进行分析研究，并以此作为计算分析复杂高边坡在高层建筑物作用下的稳定性评价的一个范例，在采用有限元弹塑性数值模拟岩质边坡稳定性方面提供一些有价值的参考。

In order to study theoretically the effects of complicated factors on traffic flow, by considering the drivers'sensitivity and prediction of forthcoming traffic situations, the deterministic deceleration step and the randomization one in the rules of the NaSch model are interchanged, which results in the sdNaSch model.

本文的工作旨在综合分析各种现有的交通流模型的基础上，提出更为符合实际的模型，并通过理论分析和数值模拟，探索交通系统中的各种非线性现象，特别侧重于交通流临界相变行为的研究，全文的工作由五部分组成

It is necessary to use the nonconventional data that has a high resolution due to the time-space limit of the conventional sounding system.

该文利用一个有限区域中尺度模式MM4，采用变分分析技术对有限区域的常规探空资料和非常规云图资料进行变分分析和数值模拟。

The multiresolution time-domain algorithm based on the scaling function of the Daubechies wavelet is introduced, and the perfectly matched layer absorbing boundary condition for the algorithm is deduced. In order to overcome the difficulties due to the nonlocalized property of the MRTD basis functions, the pure scattered-field formulation is adopted. The method presented is applied to the scattering analysis of multiple conducting objects, and the numerical results are compared with those by the traditional finite-difference time-domain method. It is shown that the computational resource is reduced drastically without sacrificing much accuracy.

对基于Daubechies小波尺度函数的时域多分辨分析算法进行了详细论述，推导了MRTD算法的完全匹配层吸收边界条件，为克服传统MRTD方法中基函数存在着非局部性的缺点，在源的加入上采用了纯散射场方法；并应用该算法对多目标的电磁散射特性进行了分析，数值结果表明，MRTD算法与传统的时域有限差分法结果相吻合，大大节约了计算资源。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。