燃气二次喷射对推力矢量控制发动机内流场的影响

采用准一维非定常N-S方程对固体火箭发动机燃气二次喷射推力矢量控制过程进行数值仿真,研究燃气引出和燃气二次喷射对发动机燃烧室及喷管内流场的影响。重点研究了燃气引出对燃烧室压强波动的影响并对其形成机理进行了初步分析。结果表明,燃气二次喷射推力矢量控制工作过程中,燃烧室压强波动很大,速度在一定程度上脉动,温度基本上不受影响。由于高温高速二次燃气的加入,喷管扩散段二次喷射孔附近及其下游喷管内压强、速度和温度有明显的变化。     

基于机内测试的故障注入系统设计

随着机内测试(Built-in Test, BIT)的深入研究和广泛应用,对其验证和评价提出了迫切要求,也使这一领域成为新的研究热点.通过故障注入的方式检测BIT性能是一种有效的验证其测试性水平的方法.在综合国内外相关研究的基础上,详细分析了BIT验证和评价的重要性、迫切性及其实用价值,着重阐述了关于BIT验证和评价的故障注入系统设计方案,并给出了系统实现的总体结构框图、工作流程图、系统中各子模块的关系图以及实验数据等.在硬/软件设计实现的基础上,进行了初步的BIT验证实验,模拟一定数量的故障注入到被测电路中,用以验证BIT测试的有效性.结果表明该故障注入系统能够满足验证BIT设计指标的要求,达到了预期的初步设计目的.      

故障注入方法与工具的研究现状

本文将故障注入技术分为基于模拟的故障注入和基于物理的故障注入两类，并从应用方法和工具结构两方面介绍了该项技术的研究现状。     

基于推力矢量控制的固体火箭发动机气体二次喷射研究

采用二维雷诺平均方程和κ-ε湍流模型,对固体火箭发动机气体二次喷射复杂干扰内流场进行了数值模拟。借助数值模拟技术,对气体二次喷射推力矢量喷管的部分方案进行了初步探索,研究了不同喷射参数对气体二次喷射流场特征及侧向控制力的影响,并分析了其原因。结果表明,二次喷射气体的喷射孔位置、喷射角及喷射总压等因素对侧向力的影响相互耦合,适中的喷射孔位置、逆流喷射角及较大的喷射总压都能有效增加侧向力及矢量角。     

凹腔超声速燃烧室氢气燃烧流场数值模拟

对带长深比为10的凹腔结构的燃烧室二维氢燃烧流场进行数值模拟,燃料喷注方式采用凹腔上游喷注加辅加凹腔前壁、底壁、后壁喷注。采用三阶MUSCL格式求解二维含组分守恒N-S方程组,湍流模型采用剪切修正的RNGk-ε湍流模型,对喷氢燃烧工况进行了计算研究,并分别分析了凹腔中不同燃料喷注方式对燃烧特性的影响。结果表明：凹腔是火焰驻留的主要区域;凹腔上游喷注氢,可以使燃料在凹腔中混合燃烧,辅加凹腔中喷氢的三种方式对燃烧状况产生一定的影响。在凹腔前壁、底面辅加喷氢,没有增强凹腔的稳焰特性,对整个燃烧状态影响不大;在凹腔后壁喷氢,能够增加凹腔中的燃料含量,加强了回流效果,对燃烧状态影响较大。三种喷注方式都没有从根本上改变凹腔燃烧流场的特性。     

Relationship of the diffuse aurora and SAR arc dynamics to substorms and storms

Investigation results of a diffuse aurora (DA) and stable auroral red (SAR) arc dynamics based on spectrophotometric observations at the Yakutsk meridian (199°E geomagnetic longitude) are presented. The relationship of an equatorward extension of DA in the 557.7 nm emission to a substorm growth phase during the magnetospheric convection intensification after the turn of IMF B_Z to the south is shown. The formation of SAR arc during the substorm expansion phase is investigated. The association of SAR arc dynamics with the development of asymmetric ring current (substorm injection) during the main phase of a storm is analyzed. It is shown how the pulsating precipitations of energetic ring current particles develop in the outer plasmasphere based on photometric observations.     

Study of magnetic flux emergence and related activity in active region NOAA 10314

We study the extremely complex active region (AR) NOAA 10314, that was observed from March 13–19, 2003. This AR was the source of several energetic events, among them two major (X class) flares, along a few days. We follow the evolution of this AR since the very first stages of its emergence. From the photospheric evolution of the magnetic polarities observed with SOHO/MDI we infer the morphology of the flux tube that originates the AR. Using a computation technique that combines Local Correlation Tracking with magnetic induction constrains, we compute the rate of magnetic helicity injection at the photosphere during the observed evolution. From our results we conclude that the AR originated by the emergence of a severely deformed magnetic flux tube having a dominantly positive magnetic helicity.     

有迎角旋转钝锥的烧蚀滞后滚转力矩的算法

有迎角的再入旋转钝锥由于周向烧蚀滞后将产生滚转力矩。在烧蚀滞后滚转力矩的计算方法中。本文主要介绍滞后引射率和粗糙度对壁面磨擦系数联合影响的一种快速计算方法。给出计算结果与实验数据的比较，分析烧蚀滞后滚转力矩的模数随飞行参数的变化。     

Graph-tree-based software control flow checking for COTS processors on pico-satellites

 This paper proposes a generic high-performance and low-time-overhead software control flow checking solution, graph-tree-based control flow checking (GTCFC) for space-borne commercial- off-the-shelf (COTS) processors. A graph tree data structure with a topology similar to common trees is introduced to transform the control flow graphs of target programs. This together with design of IDs and signatures of its vertices and edges allows for an easy check of legality of actual branching during target program execution. As a result, the algorithm not only is capable of detecting all single and multiple branching errors with low latency and time overheads along with a linear-complexity space overhead, but also remains generic among arbitrary instruction sets and independent of any specific hardware. Tests of the algorithm using a COTS-processor-based onboard computer (OBC) of in-service ZDPS-1A pico-satellite products show that GTCFC can detect over 90% of the randomly injected and all-pattern-covering branching errors for different types of target programs, with performance and overheads consistent with the theoretical analysis; and beats well-established preeminent control flow checking algorithms in these dimensions. Furthermore, it is validated that GTCGC not only can be accommodated in pico-satellites conveniently with still sufficient system margins left, but also has the ability to minimize the risk of control flow errors being undetected in their space missions. Therefore, due to its effectiveness, efficiency, and compatibility, the GTCFC solution is ready for applications on COTS processors on pico-satellites in their real space missions.     

综合通信导航识别系统的故障注入方法研究

针对综合通信导航识别系统的综合化、模块化特点，在综合分析系统故障检测诊断机制、构建系统故障信息库的基础上，设计了一种面向综合通信导航识别系统的软件故障注入方案，可提高综合通信导航识别系统故障诊断软件的效能。通过利用此方案进行故障注入试验，验证了综合通信导航识别系统故障诊断软件的功能和性能。