Application of high-order accurate methods to solve the computational gas dynamics and aeroacoustics problems

The application of the low dissipative high-order accurate scheme for numerical solution of the Euler and Navier-Stokes equations in the two-dimensional statement is considered. The scheme of calculating space derivatives is the seven-point central-difference approximation of the fourth order with the coefficients optimized to reduce the dispersion errors. The optimized six-step Runge-Kutta method is used for evaluating the time derivatives. By means of filtration, spurious pulsations are suppressed and shocks are processed. The results of verifying the calculation scheme realized on the stationary problem of flow around the model turbine blades are presented.     

某型教练机嵌入式训练系统顶层设计技术研究

本文通过对该型教练机现有航空电子系统构型、驾驶员操作程序、接口控制文件深入研究,结合未来功能扩展需求,给出了合理的系统构型分析、功能分配、数据流规划、原相关系统软件改动分析,在此基础上还设计出了嵌入式训练系统技术方案.依据方案研制的嵌入式训练系统原理样机通过系统动态试验、航电系统地面综合试验和飞机地面通电试验,证明系统...     

A software package for computer-aided design analysis of thin-walled structures from composite materials

An algorithm of analyzing the design parameters for a thin-walled wing from composite material based on the efficient distribution of structural material between load-carrying elements is described. We consider the problems of convergence acceleration for the iteration design analysis. Also presented are the examples of determining the design parameters for a superlight aircraft wing and the rational parameters of the filler in the form of a three-dimensional rod structure.     

Water feed influence on nitric oxide emission under oxidation of near-stoichiometric air-methane mixtures

We considered the influence of temperature on the nitric oxide emission under combustion of the near-stoichiometric mixtures with and without water feed. We revealed the advantage of the method of fuel-water-air mixture combustion over that of the leaned mixture combustion.     

Calculations of shock wave energy parameters in the presence of high-voltage electrical discharge in water for the transition region

A technique for calculating the energy parameters of shock waves at electrical discharge in water is presented for the transition region of discharge channel expansion using as the base the predetermined characteristics of discharge circuit. The technique is based on the solution of energy transport equation that is similar in form to that of radiative transfer. The validity of the presented approach was experimentally verified.     

正反顺序加载下安装边螺栓预紧力分散度的数值模拟与试验验证

在航空发动机机匣安装边装配过程中,不同位置螺栓之间会产生弹性交互作用,不同加载方案会使装配后的螺栓预紧力存在一定的分散度。针对这一问题,建立了3层带止口机匣安装边3维接触有限元模型,研究不同加载方案下螺栓预紧力的施加方法。基于有限元模型数值模拟了3层机匣安装边分别在顺序加载方案、交叉加载方案和正反顺序2轮加载方案下螺栓预紧力的分散度。搭建了相应的试验装置,分别对3种加载方案的预紧力分散度进行试验验证。结果表明：采用正反顺序2轮加载后的螺栓预紧力分散度最小,在3层止口机匣安装边上采用正反顺序2轮加载方案后的螺栓预紧力分散度较小,在有限元仿真中螺栓预紧力分散度为2.43%,在试验中螺栓预紧力分散度为4.98%。采用此方案加载后,止口机匣安装边能达到更好的密封效果和较好的刚度对称性。     

考虑陀螺效应的转子动力学相似准则

针对考虑陀螺力矩的转子系统缩尺相似模型与原型是否满足动力学相似的问题,采用量纲分析法推导了考虑陀螺力矩的转子-简单支撑系统相似准则,得到了模型与原型各物理量相似比.通过求解不同相似比下Jeffcott转子系统临界转速的解析解,和利用有限元软件ANSYS对某转子系统临界转速和振型相似性进行了数值模拟,验证了所推导的考虑陀螺力矩转子系统相似准则的正确性.研究表明:考虑陀螺力矩、简单支撑和Rayleigh比例阻尼的转子系统,在相似转速下缩尺模型与原型的固有频率具有相似性,并且临界转速相似.      

Modelling of galactic Carbon in an asymmetrical heliosphere: Effects of asymmetrical modulation conditions

Observations of galactic cosmic rays (GCRs) from the two Voyager spacecraft inside the heliosheath indicate significant differences between them, suggesting that in addition to a possible global asymmetry in the north–south dimensions (meridional plane) of the heliosphere, it is also possible that different modulation (turbulence) conditions could exist between the two hemispheres of the heliosphere. We focus on illustrating the effects on GCR Carbon of asymmetrical modulation conditions combined with a heliosheath thickness that has a significant dependence on heliolatitude. To reflect different modulation conditions between the two heliospheric hemispheres in our numerical model, the enhancement of both polar and radial perpendicular diffusion off the ecliptic plane is assumed to differ from heliographic pole to pole. The computed radial GCR intensities at polar angles of 55° (approximating the Voyager 1 direction) and 125° (approximating the Voyager 2 direction) are compared at different energies and for both particle drift cycles. This is done in the context of illustrating how different values of the enhancement of both polar and radial perpendicular diffusion between the two hemispheres contribute to causing differences in radial intensities during solar minimum and moderate maximum conditions. We find that in the A > 0 cycle these differences between 55° and 125° change both quantitatively and qualitatively for the assumed asymmetrical modulation condition as reflected by polar diffusion, while in the A < 0 cycle, minute quantitative differences are obtained. However, when both polar and radial perpendicular diffusion have significant latitude dependences, major differences in radial intensities between the two polar angles are obtained in both polarity cycles. Furthermore, significant differences in radial intensity gradients obtained in the heliosheath at lower energies may suggest that the solar wind turbulence at and beyond the solar wind termination shock must have a larger latitudinal dependence.     

空间实验室大面积太阳电池阵技术研究

介绍了空间实验室大面积太阳电池阵的方案构型，并进行了模态分析、热结构耦合分析和动力学仿真分析。生产出了全尺寸的集成演示样机，进行了展开试验、主展开机构的模态试验，以及半刚性太阳电池板和二自由度驱动机构的振动试验。计算和试验结果表明，技术方案是可行的。     

基于PCI总线的主从式多轴控制器开发

针对运动控制的高精度要求,介绍了一种基于PCI(Peripheral Component Interconnect)总线的实时多轴控制系统.为了在执行复杂任务时,减少主机的工作量以及充分利用数字信号处理器(DSP,Digital Signal Processor)的数字处理能力,多轴控制器采用了主从控制结构.这种控制器还可以根据用户的需要使用串行通讯控制来代替PCI总线控制.控制器硬件的研发主要集中在多轴控制器、PCI总线接口电路和PCI局部总线的控制逻辑电路上,这些是设计控制器的关键技术.通过一个三自由度机器人沿一个空间螺旋轨迹运动的实例验证,所研发的多轴控制器可以实现具有准实时性能的高精度协调运动控制.