Numerical Analyses of Discrete Gust Response for an Aircraft

Based on Navier-Stokes equations and structural and flight dynamic equations of motion, dynamic responses in vertical discrete gust flow perturbation are investigated for a supersonic transport model. A tightly coupled method was developed by subiterations between aerodynamic equations and dynamic equations of motion. First, under the assumption of rigid-body and single freedom of motion in the vertical plunging, the results of a direct-coupling method are compared with the results of quasi-steady model method. Then, gust responses for the one-minus-cosine gust profile arc analyzed with two freedoms of motion in plunging and pitching for the airplane configurations with and without the consideration of structural deformation.

带有两个共线裂纹载流薄板的温度场及热应力强度因子

采用复变函数的方法,给出带有两个等长度共线穿透裂纹的无限大载流薄板在瞬间电流作用下,裂纹尖端附近产生的温度场的表达式,得到温度在裂纹尖端的奇异特征.在通入垂直于裂纹的均匀电流作用下,由于裂纹的存在,裂纹尖端出现绕流现象,产生焦耳热,瞬时高温形成点热源.通过点热源在金属薄板内形成的温度场, 可以导出裂纹尖端产生的热应力强度因子表达式.将其与外载荷产生的应力强度因子叠加,可建立通电状态下的断裂判据.算例分析表明,点热源在裂纹尖端附近产生的热应力强度因子为负值,可以部分抵消无穷远处施加的拉应力产生的应力强度因子的作用,进而达到止裂的目的.文中建立带有两个等长度共线穿透裂纹载流薄板的热应力强度因子的概念.其研究结果对工程结构实施电磁热效应裂纹止裂具有理论意义和实用价值.

水平弯管内气液流动对管道振动影响的实验研究

通过水平弯管内气液两相流的实验研究，分析了管道内流体流动参数对管道振动的影响，给出了在实验参数范围内影响管道振动的一些认识。初步实验结果表明，当液相流量固定不变时，气相流量的逐渐增加时，管道振动逐渐减弱。而当气相流量固定不变时，随着液相流量的增加，管道振动逐渐加剧，而且振动振幅出现极大值，随后管道振幅减小，但振动频率增大。

菱铁矿热转变过程中岩石磁学性质基本特征

利用吉林大栗子铁矿纯菱铁矿样品，系统测量了菱铁矿在空气环境的的磁化特征，揭示出其饱和曙剩磁（ＳＩＲＭ）、剩磁矫顽力（ＨＣＲ）和居里温度（ＴＣ）随加热温度升高而秘珠系列变化，菱放氧化中准稳定态性矿物磁赤铁矿是中间产物之一，并且具有较高的热稳定性，Ｘ射线衍射和穆斯堡尔效应等分析结果证实了岩石磁学研究所揭示的菱铁矿氧化中磁性矿物转变过程，菱铁矿氧化过程中结晶结构的转变可能会影响其氧化产物的磁性特性。

MMCs的冲击力学性能及拉压不对称性研究

利用动态Hopkinson装置和Instron 4026测试了15%SiC_P/Al-5Cu、15%SiC_P/2124、15%SiC_P/Al-Li、15%SiC_W/6061和30%SiC_P/6061铝合金等几种复合材料的准静态和冲击力学性能，探讨了应变率对于强度、硬化模量和失效应变等的影响。同时观察了上述材料动态拉伸断口，揭示了金属基复合材料破坏的几种不同控制机理。最后讨论了实验中发现的上述复合材料挤压不对称性的新特征，其中考虑了金属基复合材料的热失配应力和不同的损伤、破坏控制机理。

Numerical Simulation of Gaseous Detonation of H_2-O_2 Mixture with Detailed Chemical Reaction Model

采用高精度的ENO格式和基于基元化学反应的真实化学反应模型求解氢氧混合气体一维爆轰波的精细结构。采用直接起爆方法得到稳定传播的爆轰波,计算的爆轰波阵面参数和实验相当符合。对爆轰波反应区化学反应的研究表明,参与反应的不同组分具有不同类型的变化特征。网格尺寸影响的研究表明,计算结果的精度随着网格尺寸的增加而增加,并能保持较好的收敛性。移动网格研究结果表明,网格运动速度和爆轰速度接近时,两者的相互作用对计算结果产生一定影响。

求解Euler方程的区域分解方法与并行算法

将复杂形状区域划分成多块子区域，研究发展了一种多块区域之间迎风守恒型的内边界耦合方法，实现相邻子区域解的光滑过渡，使多区耦合得到总体流场的数值解。对二维翼型跨音速流动和圆板形隆起物超音速流动等进行了分区数值计算，并将计算结果与单区计算结果和实验结果作了比较。并行分区计算引入“先进先出”的同步控制等待机制，实现了高效率并行计算，还分析了影响并行效率的主要因素。

A Continuation Method of Parameter Inversion for Non-Equilibrium Convection-Dispersion Equation

Based on the homotopy mapping, a globally convergent method of parameter inversion for non-equilibrium convection-dispersion equations (CDEs) is developed. Moreover, in order to further improve the computational efficiency of the algorithm, a properly smooth function, which is derived from the sigmoid function, is employed to update the homotopy parameter during iteration. Numerical results show the feature of global convergence and high performance of this method. In addition, even the measurement quantities are heavily contaminated by noises, and a good solution can be found.

强度空间分布对脉冲激光表面强化的影响

建立了包含脉冲激光强度时空分布、温度相关的材料热物性参数以及多次相变特征在内的脉冲激光表面强化三维有限元模型。温度场和强化区深度分别得到了解析解和试验验证。针对不同脉冲能量级别，研究了强度空间分布形式和光斑几何形状对表面最高温度、强化区深度以及强化区形状等的影响。结果表明，激光强度空间分布是影响强化区的重要因素。为达到理想的强化效果，应根据不同的脉冲能量选择适当的空间分布形式和光斑几何形状。

Direct Numerical Simulation of Passive Scalar in Decaying Compressible Turbulence

The passive scalars in the decaying compressible turbulence with the initial Reynolds number (defined by Taylor scale and RMS velocity) Re=72, the initial turbulent Mach numbers (defined by RMS velocity and mean sound speed) Mt=0.2-0.9, and the Schmidt numbers of passive scalar Sc=2-10 are numerically simulated by using a 7th order upwind difference scheme and 8th order group velocity control scheme. The computed results are validated with different numerical methods and different mesh sizes. The Batchelor scaling with k(-1) range is found in scalar spectra. The passive scalar spectra decay faster with the increasing turbulent Mach number. The extended self-similarity (ESS) is found in the passive scalar of compressible turbulence.

Influence of the Processing Conditions on the Characteristics of the Clad Layers Produced with Laminar Plasma Technology

Laminar plasma technology was used to produce ceramic hardened layers of Al2O3-40% mass Ni composite powders on stainless steel substrates. In order to investigate the influences of processing conditions on the morphologies of the surface modified layers, two different powder-feeding methods were tested, one with carrier gas called the powder injection method, and the other without carrier gas called powder transfers method. The microscopic investigations demonstrate that the cross-section of the clad layers consists of two distinct microstructural regions, in which the Al2O3 phases exhibit different growth mechanisms. When the powder transfers method is adopted, the number density and volume fraction of the Al2O3 particles increase considerably and their distributions exhibit zonal periodical characteristics. When the powder-feeding rate increases, the microstructure of the Al2O3 phases changes from a small globular to a long needle shape. Finite element simulations show that the transient thermo-physical features of the pool substances, such as solidification rate and cooling rate, influence strongly the mechanisms of the nucleation and the directional growth of the Al2O3 phases in the thermal processing.

超声速气流中含灰气体点源流动特性

采用Lagrange方法，研究了超声速气流中含灰气体点源的流动特性，求得了对称辆附近激波层内的流动参数。计算数值模拟结果揭示了大惯性颗粒在激波层内沿着相互交叉的振荡轨迹运动，颗粒分布形成了高、低密度层交错出现的“多层结构”，而且粒子子在轨迹包络线附近急剧聚集。