混合发动机的研究现状及应用前景

混合发动机技术是一项新型的、具有广阔发展前景的推进技术。本文介绍了混合发动机技术发展的现状和特点,综述了国内外混合发动机技术的应用情况,分析了当前混合发动机技术研究中存在的主要技术难点。     

Observations of the ozone and nitrogen dioxide profiles in the TROICA-4 experiment

To investigate the vast area of Russia, a mobile scientific facility based in a railway carriage was developed. It is capable to perform continues measurements being coupled in a passenger train traveling along railroads. It was first equipped with a spectrometer for remote sensing of ozone and nitrogen dioxide in the atmosphere for the transcontinental observations into the chemistry of the atmosphere-4 expedition performed from February 18 to March 5, 1998. A twilight DOAS method, which was applied for retrieval of the nitrogen dioxide profiles basing on spectral measurements at the visible wavelengths (434–451 nm), is described in the paper. Main features of a new algorithm for retrieval of the ozone profile and total content using the differential structure of the UV spectrum (310–335 nm) are presented. The ozone and nitrogen dioxide contents are obtained and shortly validated against available alternative data.     

Re-entry trajectory tracking of reusable launch vehicle using artificial delay based robust guidance law

A Reusable Launch Vehicle (RLV), during the re-entry phase of its flight, experiences uncertain environment and extreme turbulence. This calls for an effective control strategy to guide the vehicle efficiently on a trajectory that allows safer landing conditions while providing robustness against external disturbances and system uncertainties. In this regard, a Time-Delayed Control (TDC) strategy has been proposed to track the space vehicle on a predetermined trajectory in the presence of these uncertainties. In the proposed approach, the system vector and the uncertainties are lumped into a single function which is estimated using the input and output data from the previous instant. Theoretical analysis of the control strategy executed using Lyapunov’s method, proves Uniformly Ultimately Bounded (UUB) stability of the closed loop system. The efficacy of the proposed approach has been verified through simulation studies which affirm robust tracking of the optimal trajectory generated through Pseudo-Spectral method (PSM), in the presence of time-varying uncertainties.     

中国航天进入无人航天与载人航天相结合的新时期--"十五"计划期间中国航天发射情况述评

回顾了"十五"计划期间中国的航天发射情况,比较了各五年计划期间中国的航天发射情况,讨论了"十五"计划期间中国航天发射的特点.     

下一代主力运载火箭发展思考

针对我国下一代主力运载火箭后续发展问题,首先回顾了世界主要航天国家和地区运载火箭发展历程,分析了当前我国运载火箭发展问题,基于运载火箭自身代际发展技术规律和外部发展需求两方面,构建了运载火箭发射效能公式,据此提出了我国下一代主力运载火箭4个重点发展方向,最后给出了发展目标和建议。     

基于期望任务寿命的可重复运载火箭RMT参数规划模型研究

随着世界航天领域科技的高速发展,可重复运载火箭一直是国内外的研究热点。伴随着该技术的蓬勃发展,高可靠性、高安全性、高质量成为新一代运载火箭设计目标,在可重复运载火箭的高可靠性背景下,对系统的可靠性、维修性、测试性的相关指标进行设计与参数规划显得尤为重要。针对上述问题,综合运用可靠性工程理论、可用度、马尔可夫状态转移过程理论等等,准确地对可重复运载火箭的发射过程进行解析,并且根据复杂装备的指标要求,对其进行分析与研究,最终得到一个较为可靠的可重复运载火箭RMT指标的参数规划模型。     

磁控热防护系统在天地往返运载器上的应用仿真

磁控热防护技术在高超声速领域显现出广泛的应用前景。考虑高超声速流动磁流体力学控制涉及的等离子体生成机制、多电离组分导电机理以及电磁流动能量/动量输运机制,通过耦合求解电磁场泊松方程和带电磁源项的高温热化学非平衡流动控制方程组,搭建了高超声速磁控热防护数值模拟平台。结合美国航天飞机\"哥伦比亚\"号（OV-102）近似外形和5种磁场配置方案,较为系统地开展了磁控热防护系统在高超声速\"滑翔返回式\"天地往返运载器上的应用仿真研究。结果表明：搭建的磁控热防护仿真平台具备偶极子磁场、均匀磁场、螺线管磁场及多个磁场组合条件下复杂外形飞行器气动热环境数值模拟能力,其校验结果与文献或飞行试验数据符合较好;采用合适的磁场配置能有效降低航天飞机的表面热流,显著改善了航天飞机的气动热环境,典型状态的表面热流下降25%以上;局部磁场方向与流动方向的夹角,在一定程度上决定了洛伦兹力的强度和方向,对磁控效果的影响明显。     

CP—20卡槽零件一次滚弯成形

介绍了在自制简易滚床上，改进滚模设计，替代原滚边－－折弯相结合的工艺方法，实现一次滚弯成形。改进后的形成方法，保证了产品质量，提高工效８倍，原材料也得到充分利用。     

机动发射下空间飞行器上升段弹道快速计算方法

机动发射条件下,为提高空间飞行器变射面横向机动模型的诸元计算速度,设计了基于牛顿迭代算法的诸元快速计算模型。以基准弹道诸元参数为迭代初值,选取了6个关键参数,在同一弹道模型基础上,采用牛顿迭代法对诸元进行快速求解。仿真结果表明,在一定范围内,迭代后的变射面横向机动弹道能够与飞行中段弹道高精度交班,且计算耗时不超过2 s,能够满足机动发射需求。