基于有限元法的电磁铁磁场的计算机定量分析

随着工程领域中对电磁铁磁场分析的计算精度要求的不断提高,要求有新的数值分析方法以适应这一需求,有限元法即是符合这一需求的分析方法。主要阐述了应用有限元法分析数字阀电磁铁问题的基本思想,并运用该方法对产品前期设计进行了精密的计算和性能预测,节省了大量的设计费用,经济可比性较高。     

Analysis of dynamic behaviour of inflatable booms in zigzag and modified zigzag folding patterns

The deployment behaviour of inflatable booms with zigzag and modified zigzag folding patterns is experimentally and theoretically investigated in this paper with the aim to deploy the booms as the actuator for future deployable large-scale membrane structures. Regarding the experimental approach, the stable deployment of a modified zigzag folding pattern is demonstrated, and the relation between stable and unstable deployment behaviour is considered in relation to air pressure and flow rate. In terms of the theoretical approach, the folding process and deployment behaviour are simulated using commercially available software (PAM-CRACH and PAM-SAFE). To create folding lines from the zero stress condition in the case of analytical inflatable boom models, the stress distribution and the shapes of the folding lines are considered for the initial self-deployment behaviour and deployment behaviour using the uniform pressure method. From the folding experiments and the results of folding analyses and UPM, the deployment behaviour of inflatable boom models in zigzag and modified zigzag folding patterns is compared by using the finite point-set method. For the sequential deployment behaviour, which is difficult to replicate, the uniform pressure method is used for the calculations, and the relation between inlet air flow and stable deployment behaviour is discussed through comparison of the experimental and analytical results.     

LC9型材机翼前梁制造工艺

农5飞机机翼前梁主缘条，采用LC9合金型制造，零件细长，外形复杂，成形和协调难度大。本文简要介绍了该零件的制造工艺。     

Numerical Simulation of Rotor-aerodynamic Surface Interaction in Hover Using Moving Chimera Grid

Three-dimensional unsteady Navier-Stokes equations are numerically solved to simulate the aerodynamic interaction of rotor, canard and horizontal tail in hover based on moving chimera grid. The variations of unsteady aerodynamic forces and moments of the canard and horizontal tail with respect to the rotor azimuth are analyzed with the deflection angle set at 0° and 50°, respectively. The pressure map of aerodynamic surfaces and velocity vector distribution of flow field are investigated to get better understanding of the unsteady aerodynamic interaction. The result shows that the canard and horizontal tail present different characteristics under the downwash of the rotor. The canard produces much vertical force loss with low amplitude fluctuation. Contrarily, the horizontal tail, which is within the flow field induced by the down wash of the rotor, produces only less vertical force loss, but the amplitudes of the lift and pitching moment are larger, implying that a potential deflection angle scheme in hover is 50° for the canard and 0° for the horizontal tail.     

小展弦比飞翼布局作战飞机可控性设计方法

 飞翼布局飞机取消了常规布局飞机采用的安定面和操纵面,由此引起其可控性设计的诸多新问题。以某小展弦比飞翼布局作战飞机为例,利用风洞试验结果研究了几种典型新型操纵面的操纵新机理及不同飞行条件下的操纵效能等。基于可控性设计的要求,估算了该飞翼构型作战使用所需的三轴最大控制力矩系数。通过引进舵容量的概念提出了新型操纵面的参数化设计方法,最后对这一新布局方案进行了可控性评估,为飞翼布局飞机概念设计阶段的新型操纵面布置和设计提供了一种实用的方法。     

弹性与后掠角对三角翼绕流结构的影响

为了研究低雷诺数下微小型飞行器布局的流动机理,在水槽中对展长/根弦长之比为0.5的一系列变弹性和后掠角机翼的绕流结构进行了氢气泡流动显示实验.结果表明,在低雷诺数条件下,流动结构变化规律如下:随着后掠角增大,弹性翼绕流遵循"Ω涡一对前缘涡一对前缘涡与双涡一对前缘涡、双涡与三涡一对前缘涡与双涡一对前缘涡"的变化规律,刚性翼绕流的涡结构变化规律与弹性翼相似,但不存在三涡结构.     

Topological model of the solar event including a flare and coronal mass ejection on October 19, 2001

Based on the analysis of a strong solar flare X1.6/2B on October 19, 2001 in the active region 9661, accompanied by a coronal mass ejection (CME) of the halo type, a topological model of development of this solar event is suggested. The model considers a unified process of development of CME and a chromosphere flare. According to the model, this process has a common source of energy supply: the turbulent current layer lying between the arcade of flare loops and the surface of CME going away. The structures on the ends of flare bands (SEFB) represent in this model chromosphere feet of the system of large-scale coronal magnetic arches at the initial stage of the dynamic processes whose evolution results in CME. Peripheral structures (PS) of the flare (elongated double bright emission strips beyond the limits of the active region) are interpreted as chromosphere bases of magnetic field lines that form an external shell (braid) of the CME at the late stage of the flare.     

Some peculiarities of changes in characteristics of proper atmosphere of space objects

We consider the behavior of the proper atmosphere of space objects in interaction with a flow of incident particles and when the orientation of an object changes. An asymmetry in the behavior of a sorption film with respect to an incident flow of atmospheric particles and the flow’s angular characteristics is shown, as well as the film influence on operation of sensors of the spacecraft’s attitude control system. A recommendation concerning usage of heavy gases for technological operations onboard spacecraft is given.     

Parametric resonance in the solar corona

When studying microwave emission of active regions on the Sun, an effect of parametric resonance between 5-min velocity oscillations in the solar photosphere and sound oscillations of coronal magnetic loops modulating the microwave emission has been discovered for the first time. The effect shows itself as simultaneous excitation in coronal magnetic loop of oscillations with periods 5, 10, and 3 min, which correspond to the pumping frequency, subharmonic, and the first upper frequency of parametric resonance. The parametric resonance can serve as an effective channel of transporting the energy of photospheric oscillations into the upper layers of the solar atmosphere. This effect opens up the important prospects in understanding the mechanisms of coronal plasma heating.     

Impact of helio-and geophysical disturbances on thermobaric and climatic characteristics of the Earth’s troposphere

We present the mechanism and the concept of a model of the solar activity impact on thermobaric and climatic characteristics of the troposphere. Both are based on the idea of parametric action. The results of analysis are presented concerning specific features and regularities of changes in temperature regime of the troposphere in the period of variable helio-and geophysical activity, as well as long-term variations of temperature and heat content of the troposphere. The influence of changes in circulation in the atmosphere and ocean on processes in the system atmosphere-ocean-cryosphere is considered: thermohaline circulation of the oceans and energy exchange between the atmosphere and ocean. The revealed regularities find their complete explanation within the context of a model and mechanism of solar activity impact on climatic characteristics of the troposphere that were suggested previously by the authors.