涡轮风扇发动机紧凑压缩系统气动性能

通过数值方法研究了由2级风扇、4级高压压气机及外涵组成的紧凑压缩系统的气动性能.探讨了双涵双轴压缩系统气动性能的评估方法及数值计算中相应的边界给定方法.通过对紧凑压缩系统的一体化数值模拟,分别获取了风扇及高压压气机的设计转速特性,并与设计值进行了对比,结果表明流量、压比、效率都达到了设计要求,而风扇失速裕度仅为7.8%...     

飞行模拟器电动操纵负荷系统多余力抑制研究

飞行模拟器操纵负荷系统是一种被动式力伺服系统,其多余力的抑制是提高操纵负荷系统力跟踪精度的关键。以研制的飞行模拟器电动操纵负荷系统原理样机为平台,对系统的工作原理和结构进行介绍,通过系统建模,在MATLAB/SIMULINK中仿真,对经典的前馈补偿和PID复合控制方法的多余力抑制效果进行仿真分析,并在原理样机上进行试验测试。试验结果验证了复合控制策略有效地抑制了多余力,提高了系统的跟踪精度。     

Optimization design of satellite separation systems based on Multi-Island Genetic Algorithm

The separation systems are crucial for the launch of satellites. With respect to the existing design issues of satellite separation systems, an optimization design approach based on Multi-Island Genetic Algorithm is proposed, and a hierarchical optimization of system mass and separation angular velocity is designed. Multi-Island Genetic Algorithm is studied for the problem and the optimization parameters are discussed. Dynamic analysis of ADAMS used to validate the designs is integrated with iSIGHT. Then the optimization method is employed for a typical problem using the helical compression spring mechanism, and the corresponding objective functions are derived. It turns out that the mass of compression spring catapult is decreased by 30.7% after optimization and the angular velocity can be minimized considering spring stiffness errors. Moreover, ground tests and on-orbit flight indicate that the error of separation speed is controlled within 1% and the angular velocity is reduced by nearly 90%, which proves the design result and the optimization approach.     

Uncertainties and effects on geocenter motion estimates from global GPS observations

Global positioning system (GPS) observations can be used to estimate the geocenter motion, but are subjected to large uncertainties and effects due to uneven distribution of GPS stations and high-degree aliasing errors. In this paper, uncertainties and effects on geocenter motion estimates from global GPS observations are investigated and assessed with different truncated degrees and selected GPS network distributions based on different plate motion models, including NUVEL-1A, MORVEL56 and ITRF08. Results show that the selected GPS stations have no big effects on geocenter motion estimates based on different plate motion models, while large uncertainties are found at annual and semi-annual components when using different truncated degrees. Correlations of geocenter motion estimates from selected GPS networks with GRACE and SLR are better with truncated degree 3, and higher truncated degrees will degrade geocenter estimates. Smaller RMS also shows better results with the truncated degree 3 and the NUVEL1A has the worse results because more GPS sites are eliminated. For annual signal with truncated degree 3, four GPS strategies can reduce annual amplitudes by about 29.2% in X, 5.6% in Y, and 27.9% in Z with respect to truncated degree 1. Annual phases of all GPS solutions from MORVEL56 and ITRF08 are almost close to the GRACE solution with truncated degrees from 3 to 10, while the semi-annual signals are relatively weaker for all cases.     

霍尔电推进离子能量后加载设计及工作特性

典型的全电推进通信卫星通常设计使用寿命约为15年,对霍尔电推力器的使用寿命要求达到了104h量级,因此,长寿命设计技术是影响其能否工程应用的关键技术.简要调研了国内外霍尔推力器延寿技术的发展,分析得到壁面及磁极腐蚀程度是影响推力器寿命的核心物理过程.通过分析推力器放电过程离子加速场的建立过程,提出一种具有离子能量后加载...     

发动机试车台推力测量系统中心加载现场校准技术研究

介绍了发动机试车台推力秤中心加载校准方法,并与平面加载校准方法进行了试验比较,进而得出相应结论。     

轻型通用飞机发动机功率估算方法

在轻型通用飞机总体设计阶段的参数设计中,快速准确地预估发动机总功率数值是其重要的一步.选定发动机型号,根据设计目标与适航要求等约束条件,统计大量轻型通用飞机的相应总体参数数据与发动机信息,研究得出经验公式及参数之间的函数关系,计算发动机总功率的对应取值区间.结果表明:在同时满足设计目标与适航要求的约束条件下,可获得发动机总功率数值的取值交集,对更加快速准确地选出合适的发动机具有重要的指导作用.     

用等效平均损伤模型计算剩余寿命方法的研究

分析了复杂载荷下材料的损伤累积过程和疲劳寿命计自身材料疲劳损伤与其不可逆电阻变化响应的联系。疲劳寿命计自身材料疲劳损伤演变、损伤累积过程以电阻变化速率和变化量显示了其全貌。假设其等效平均损伤等一般规律与金属材料的疲劳情况相类似,结合本文给出拟合精度很好的材料应力寿命曲线,得出随机载荷下剩余寿命计算的简便方法,具有较高可信度。初步实验验证很令人满意。     

飞机结构试验用加载作动器设计与效率分析

针对飞机结构试验尤其是静力试验中加载速度低、系统流量低的特点,设计了一种新型的基于阀控的飞机结构加载试验用的电液一体化作动器,阐述了其系统组成和工作原理,分析了阀控系统的效率问题,提出降低油源压力设计值来提高系统效率的方案,并通过AMESim高级建模仿真平台,对该电液一体化作动器系统进行建模仿真,验证了降低油源压力设计值方案对提高系统效率的有效性.其仿真结果表明所设计的电液一体化作动器能够满足设计要求,在飞机结构加载试验中具有很好的应用前景.     

三维机织芳纶／环氧复合材料应变率压缩响应研究

研究三维机织芳纶/环氧复合材料在高应变率下的压缩力学性能.运用分离式霍普金森杆(SHPB)测试不同应变率在复合材料厚度方向的压缩性能,同时对材料在准静态情况的力学性能进行测试,与高应变率下的力学性能比较表明,三维机织芳纶/环氧机织复合材料是应变率敏感材料,随着应变率的增加,压缩刚度和最大应力增加,而相应最大应力的应变则减小.