高超声速双模块内转式进气道的流动特性研究-Part II 攻角影响

为了研究飞行攻角对高超声速双模块内转式进气道流动的影响,本文通过试验和仿真方法,获得了0°,4°和6°攻角条件下进气道模块内的流动结构。结果表明：在本文研究的攻角范围内,进气道均可起动,进气道压缩面侧的压力变化体现了基准流场的流动特性。在耦合作用下进气道模块间压缩面诱导的激波形态沿流向由弓形逐渐发展为钟形,并且在外压缩激波的扫掠影响下进气道的三个角区出现了强度不同的旋涡结构。进气道压缩面侧的角区旋涡随着攻角的增加而逐渐增强,而进气道出口截面上低能流区域随着攻角的增加而逐渐减小。低能流区域内的二次旋涡呈现不同的变化趋势,位于上半截面的旋涡随着攻角的增加其逐渐向上移动,而位于下半截面的旋涡位置基本保持不变。     

四轮起落架飞机地面滑跑转弯分析

现代飞机对其地面滑跑性能的要求日益提高,同时要求能够在条件更加苛刻的环境下运行.以四点式起落架布局飞机为研究对象,基于阿克曼转向几何原理,推导该飞机地面滑跑时两个前轮之间的转角关系.在Adams/Aircraft中建立四点式起落架飞机虚拟样机,并进行其地面滑跑仿真分析.探讨四点式起落架飞机不同前轮作为主动操纵轮时,对转弯半径的影响.结果表明:在相同滑跑条件下,当前轮操纵转弯时,四点式起落架飞机比常规的前三点式起落架飞机拥有更小的转弯半径;当主轮差动刹车转弯时,四点式起落架飞机的转弯半径略大于三点式起落架飞机;四点式起落架飞机的两前轮同时为主动操纵轮时,飞机的转弯半径最小.     

风云一号气象卫星星载天线隔离技术

为消除风云一号(FY-1)气象卫星星栽天线间的耦合，对天线间距离和极化形式对天线隔离度的影响进行了分析和试验，认为前者是影响星栽天线间隔离度的主要因素。据此，采取了利用卫星整流罩空间，选择天线极化方向、设置隔离器和滤波器抑制电磁干扰等综合措施来提高FY-1卫星天线间的隔离度。最终测试表明，所设计的天线系统布局合理，整星状态下天线电性能满足任务书要求。     

非线性比例导引系统研究

研究了非线性比例导引系统的性能。利用一种单输入双输出二阶非线性状态估计器估计弹目视线角速度和角加速度，状态估计器的输入直接采用来自导引头的信息，其输出量可以给出弹目视线角速度和角加速度的估计值，将此估计量作为补偿信号引入到比例导引系统中，形成了非线性比例导引系统。仿真研究表明，这种非线性比例导引具有良好的制导特性。     

用导弹"视频遥测"信号推算导弹脱靶量

论述了采用某导弹战斗弹遥测系统中的“视频遥测”信号推算导弹靶试时脱靶量的原理，介绍了两种处理脱靶量的方法。根据该导弹某次靶试时的遥测数据，对导弹的脱靶量进行了推算。推算结果证明，遥测数据的处理结果与光测数据的处理结果相近，用导弹“视频遥测”信号推算导弹脱靶量的方法具有一定的参考意义。     

基于建模仿真的飞机桶滚机动规避空空导弹效果及原因分析

基于飞机桶滚机动规避空空导弹攻击的作战背景,建立了导弹与飞机的空间交会模型。以导弹脱靶量、过载以及舵偏角速率为依据,对桶滚机动不同机动时机、周期下的规避效果以及规避原因进行了仿真分析。研究结果表明,导弹脱靶量与机动时机的关联性较弱,可随着机动周期的增大而减小。当机动周期为 2~3 s时,导弹脱靶量较大,飞机规避效果较好。飞机桶滚机动规避导弹的原因不仅在于导弹交会过程中过载的增大,而且还在于导弹交会过程中舵偏角速率的增大。     

On the association of quiet-time Pi2 pulsations with IMF variations

The association of quiet-time Pi2 pulsations with the variations of the interplanetary magnetic field (IMF) has been examined by using three reported events, occurring during extremely quiet intervals, of which the first was on 10 March 1997, the second 27 December 1997, and the third 11 May 1999. For the first event, the onset time of ground Pi2s maps to the IMF structure bearing a variation cycle of north-to-south and north again as seen by Wind in the upstream region and Geotail in the magnetosheath. Likewise, the second and the third events have respectively, four and three recurrent turnings propagating to the Earth sensed by multiple satellites. The comparison of geomagnetic perturbations, auroral brightenings, and energetic particle data in the magnetotail with the IMF observations shows successive substorm-like activations accompanied by ground Pi2 onsets. For a clear variation cycle, the first Pi2 burst appears 36 ± 8 min after southward turning of the IMF and the second one follows14 ± 4 min after a northward turning. Moreover, ground Pi2 onsets recur under low IMF clock angle conditions. These observational results can be interpreted with the prevailing models of externally triggered substorm. But the solar wind coupling to the magnetosphere under quiet conditions proceeds in a less efficient way than under substorm time conditions. Consequently, we suggest that recurrent quiet-time Pi2s can be associated with IMF variations and their cause can be the same as those for substorm times.     

A parameterized geometry design method for inward turning inlet compatible waverider

Intensive studies have been carried out on generations of waverider geometry and hypersonic inlet geometry. However, integration efforts of waverider and related air-intake system are restricted majorly around the X43A-like or conical flow field induced configuration, which adopts mainly the two-dimensional air-breathing technology and limits the judicious visions of developing new aerodynamic profiles for hypersonic designers. A novel design approach for integrating the inward turning inlet with the traditional parameterized waverider is proposed. The proposed method is an alternative means to produce a compatible configuration by linking the off-the-shelf results on both traditional waverider techniques and inward turning inlet techniques. A series of geometry generations and optimization solutions is proposed to enhance the lift-to-drag ratio. A quantitative but efficient aerodynamic performance evaluation approach （the hypersonic flow panel method） with lower computational cost is employed to play the role of objective function for opti- mization purpose. The produced geometry compatibility with a computational fluid dynamics （CFD） solver is also verified for detailed flow field investigation. Optimization results and other numerical validations are obtained for the feasibility demonstration of the proposed method.