某型发动机压气机叶片对性能的影响分析

采用CFD数值模拟方法和厂内试车方法,对某型发动机压气机叶片设计状态(A状态)和产品实际情况(B状态,转接半径、叶型厚度偏离较大)下,叶片前缘形状对发动机性能的影响进行了分析和试车验证,结果表明:B状态叶片,气流沿叶型整个型面附面层厚度呈迅速增大趋势,在较大区域较早出现气流分离,易导致压气机处于非稳定性状态工作;试车结果表明其导致整机推力性能降低。     

基于改进ConvNeXt模型的压气机变几何系统T-step预测方法

为了实时监控航空发动机压气机变几何系统的状态并获取警告信号，提出一种基于改进ConvNeXt 模型的T步（T-step） 预测方法。与仿真数据和特定试验条件下生成的数据集相比，T-step预测方法采用了飞机数据采集系统记录的实际飞行数据。 证实了采用改进ConvNeXt模型预测压气机变几何系统参数的可行性，并在发动机过渡状态和稳态下分别进行了试验验证。结果 表明：采用改进ConvNeXt模型的T步（T-step）预测方法能精准地预测压气机VSV角度和VBV开度的变化，最低可达2.132°和 7.077°，预测误差在可接受范围内。该方法能识别和预测各类型航空发动机不同运行状态的变几何系统参数的角度，获得相对准 确的结果。     

Configuration studies for active electrostatic space radiation shielding

Developing successful and optimal solutions to mitigating the hazards of severe space radiation in deep space long duration missions is critical for the success of deep-space explorations. Space crews traveling aboard interplanetary spacecraft will be exposed to a constant flux of galactic cosmic rays (GCR), as well as intense fluxes of charged particles during solar particle events (SPEs). A recent report (Tripathi et al., Adv. Space Res. 42 (2008) 1043–1049), had explored the feasibility of using electrostatic shielding in concert with the state-of-the-art materials shielding technologies. Here we continue to extend the electrostatic shielding strategy and quantitatively examine a different configuration based on multiple toroidal rings. Our results show that SPE radiation can almost be eliminated by these electrostatic configurations. Also, penetration probabilities for novel structures such as toroidal rings are shown to be substantially reduced as compared to the simpler all-sphere geometries. More interestingly, the dimensions and aspect ratio of the toroidal rings could be altered and optimized to achieve an even higher degree of radiation protection.     

几种典型航天测控系统的最优布站

在测轨道某点风险函数最小准则下，研究了几种典型测控系统的最优布站和特性。这些系统是：测角（α、γ）体制的光学经纬仪；测距测角（Ｒ、Ｅ、Ａ）体制的脉冲雷达；测距离（Ｒ）［或测速（Ｒ）］体制的多Ｒ［或多（Ｒ）］系统。导出的结果公式计算十分简单，能估算测控系统定轨的精度极限。对试验场的设备布局、安置勘点、总体设计、精度估算与控制等，具有实际参考价值     

Analyzing Qualitative Spatio-Temporal Calculi using Algebraic Geometry

Abstract

Qualitative spatial reasoning is based on calculi which comprise relations and operation tables that encode operations like relation composition. Designing a calculus involves determining these tables and analyzing reasoning properties—a demanding task that is susceptible to errors if performed manually. This paper is concerned with automating computation of operation tables and analysis of qualitative calculi over real-valued domains like the plane ². We present an approach to specify qualitative relations using polynomial equations that allows methods from algebraic geometry to be applied. This paper shows how reasoning with qualitative relations can be posed algebraically and demonstrates algebraic reasoning using Gröbner base analysis. We evaluate this approach and describe our implementation, which is freely available as part of the spatial reasoning toolbox SparQ.     

A 3D hybrid grid generation technique and a multigrid/parallel algorithm based on anisotropic agglomeration approach

A hybrid grid generation technique and a multigrid/parallel algorithm are presented in this paper for turbulence flow simulations over three-dimensional (3D) complex geometries. The hybrid grid generation technique is based on an agglomeration method of anisotropic tetrahedrons. Firstly, the complex computational domain is covered by pure tetrahedral grids, in which anisotropic tetrahedrons are adopted to discrete the boundary layer and isotropic tetrahedrons in the outer field. Then, the anisotropic tetrahedrons in the boundary layer are agglomerated to generate prismatic grids. The agglomeration method can improve the grid quality in boundary layer and reduce the grid quantity to enhance the numerical accuracy and efficiency. In order to accelerate the convergence history, a multigrid/parallel algorithm is developed also based on anisotropic agglomeration approach. The numerical results demonstrate the excellent accelerating capability of this multigrid method.     

TBCC用轴对称进气道流量控制技术研究

为了满足组合动力进气道在宽马赫数范围内良好工作,开展了组合动力轴对称进气道设计,提出了多种轴对称进气道变几何方案以实现进气道/发动机流量匹配。理论分析及数值模拟研究了各变几何机制的可行性,对比分析各方案优劣。结果表明:外压段溢流、内压段溢流及扩压段溢流均能实现进气道/发动机流量匹配;外压段溢流变几何机制较复杂,其中改变唇罩角度和移动部分中心锥时进气道总压恢复系数较高,且移动部分中心锥时进气道压差阻力较小;内压段溢流各方案变几何机制相对简单,但溢流区域较大,斜激波易导致中心锥表面流动分离。其中采用外罩设置放气孔的形式时,进气道总压恢复系数较高,压差阻力较小;扩压段溢流方案实现简单,溢流区域小,进气道性能较好。      

变几何变工质涡轮性能预测及变工况性能计算

为适应涡轮在变工质，大变工况条件下的性能预测，研究了工质的性质，涡轮各种损失与涡轮流通通道内的临界堵塞流动，变几何涡轮的性能计算方法。这些研究的结果是变几何变工质涡轮理论分析的有用工具。     

利用极化信息实现目标重构的算法研究

本文研究了一个光滑的、理想导电的、凸散射体的轮廓重构问题。主要从物理光学散射场的一阶修正项入手,分析了散射场的共极化和交叉极化信息与目标表面形状之间的关系,获得了散射场的极化特性与散射体表面上镜面点的主曲率密切相关的概念。借助于微分几何中曲面再现问题,重构出目标的外形图象。     

RESEARCH ON NURBS SKINNING SURFACE VIA COMPLEX CURVES

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