感应同步器测角系统误差分析及补偿

本文讨论了提高感应同步器精度的硬件方法和软件方法。硬件方法即根据误差来源，针对不同谐波成分误差，用电路调节的方法消除误差。软件方法就是采用计算机通过误差曲线拟合来减小误差。     

周边切口短圆柱试件的杆杆型冲击拉伸试验系统的弹塑性有限元分析

基于一维试验原理提出了用带有周边切口的短金属圆柱试件进行平面应变型弹塑性动态断裂韧度的测试方法；对该复杂的动力学系统进行了轴对称的弹塑性有限元分析，并计算了动态围道^J积分；根据对试件功能转换关系的分析和Rice公式的物理意义，提出了用试件两端平功载荷－两端相对位移曲线（P^-△）推广Rice公式计算试件的远场J积分，由此得到的P^-△曲线基本上消除了与裂纹运动无关的质心运动动能的影响。论证了J积分作为裂端的表征参量，且当切口深度比大于70％时，Rice公式有较高的计算精度，为平面应变型弹塑性动态断裂韧度的表征与测试提供了依据。     

Inverse problem for the viscoelastic medium with discontinuous wave impedance

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气固两相圆射流场涡结构影响固粒扩散的研究

用三维离散涡丝方法模拟轴对称圆射流场涡结构的发展·所得结果在某个周向位置上与用二维点涡方法计算的结果符合较好·然后采用单向耦合模型模拟固粒在圆射流中的运动,说明当固粒Ｓｔ数远小于１时,固粒受流场的作用较明显,当Ｓｔ数为１时,固粒主要分布在涡结构的周围,分布较均匀;当Ｓｔ数远大于１时,固粒受流场的影响较弱·当对涡环沿周向施以五个波长的扰动时,固粒扩散的范围较宽·固粒的扩散与扰动的振幅成正比·文中所得结论与一些实验结果相符,对实际应用有指导意义     

Particle modulations to turbulence in two-phase round jets

The particle modulations to turbulence in round jets were experimentally studied by means of two-phase velocity measurements with Phase Doppler Anemometer （PDA）. Laden with very large particles, no significant attenuations of turbulence intensities were measured in the farfields, due to small two-phase slip velocities and particle Reynolds number. The gas-phase turbulence is enhanced by particles in the near-fields, but it is significantly attenuated by the small particles in the far-fields. The smaller particles have a more profound effect on the attenuation of turbulence intensities. The enhancements or attenuations of turbulence intensities in the far-fields depends on the energy production, transport and dissipation mechanisms between the two phases, which are determined by the particle prop- erties and two-phase velocity slips. The non-dimensional parameter CTI is introduced to represent the change of turbulence intensity.     

旋转运动导电圆板的磁弹性参数振动分析

针对磁场中旋转运动圆板,在动能、应变能表达式基础上,根据哈密顿原理导出圆板的磁弹性振动方程．应用伽辽金积分法,得到横向磁场中旋转变速运动圆板的轴对称参数振动微分方程．通过坐标变换得到包含两个变系数项的马蒂厄振动方程．应用弗洛凯理论和平均法对系统的参数振动问题进行求解．通过数值计算得到周期稳定图、对应的振动响应特性图和相轨迹图．结果表明：在稳定区域内,系统的幅频曲线呈现为周期或概周期变化形式;在不稳定区内,系统的幅频响应曲线呈现为发散变化形式．     

Reacting, Circular Mixing Layers in Transition to Turbulence

The evolution of a reacting, circular mixing layer - a model of round-jet flow - in its transition to turbulence was studied by direct numerical simulation. An economical Fourier pseudospectral method was combined with the third-order Adams-Bashforth scheme to integrate Navier-Stokes and scalar transport equations. The Reynolds number based on initial mixing-layer diameter and velocity difference was 1600. The initially thin mixing layer encloses a cylindrical core of fuel that mixes and reacts with the surrounding oxidizer. Both fast and finite-rate reactions were examined. The stages in transition are characterized by roll-up of the mixing layer into a sequence of vortex rings, pairing of adjacent rings, azimuthal instability, and breakdown to a disordered (turbulent) state. Reaction surfaces in the fast reaction limit become extended, folded and pinched off at various times corresponding to the dynamics of the vortices observed in the simulations. When the equivalence ratio is O(1) or smaller,the progress of reaction is determined by the dynamics of vortex rings. For larger ratios there is a qualitative difference: Initially, the flame is located well outside the rings and is relatively unaffected. Following breakdown to turbulence, there is a steep increase in flame surface area resulting in a noticeable change in fuel consumption rate. At smaller reaction rates (small Damkohler numbers), the reaction zones are diffuse and fill the vortical (mixed) regions. Product accumulates in and its presence raises the temperature of vortex cores, but reaction rates remain low due to low reactant concentrations. Reaction rates are highest in the braids between vortex rings where scalar dissipation rates and compressive strain rates show the highest values. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effect of temperature dependent viscosity on revolving axi-symmetric ferrofluid flow with heat transfer

The prime objective of the present study is to examine the effect of temperature dependent viscosity μ(T) on the revolving axi-symmetric laminar boundary layer flow of an incompressible, electrically non-conducting ferrofluid in the presence of a stationary plate subjected to a magnetic field and maintained at a uniform temperature. To serve this purpose, the non-linear coupled partial differential equations are firstly converted into the ordinary differential equations using well-known similarity transformations. The popular finite difference method is employed to discretize the non-linear coupled differential equations. These discretized equations are then solved using the Newton method in MATLAB, for which an initial guess is made with the help of the Flex PDE Solver. Along with the velocity profiles, the effects of temperature dependent viscosity are also examined on the skin friction, the heat transfer, and the boundary layer displacement thickness. The obtained results are presented numerically as well as graphically.     

Numerical study on the stability and mixing of vertical round buoyant jet in shallow water

IntroductionAsimplewaytodisposeofthelargequantitiesofwasteheatresultingfromsteamelectricpowergeneration ,istodischargetheheatedcondenserwaterthroughasubmergedroundoutfalllocatedatthebottomofthereceivingwater.Inrecentyears,suchkindsofhighvelocityinjectionsystemshaveincreasinglybeenusedaseffectivemixingdevices,frequently ,thesedevicesarelocatedinwatersofonlyafewportdiametersdeep ,anddischargingareaisrelativelysmall.Thusanunderstandingoftheinducedexcesstemperaturedistribution ,inrelationshiptothe…