叶轮机非定常气动设计的缘线匹配(II)数值研究

缘线匹配通过考虑多叶排叶轮机相邻叶排间前排叶片尾缘线与后排叶片前缘线空间相对位置匹配关系来进一步提升叶轮机性能,有潜力使叶轮机非定常设计走向工程实际。以一单级跨声轴流压气机和一单级轴流透平为例,尝试用基元流动展向积分方法和全优化方法改善其性能,从而示例应用缘线匹配的具体方法及前景。结果表明,缘线匹配为叶轮机非定常设计提供了可操作的自由度。     

复合材料动模量振动测定方法的研究

 本文采用Timoshenko梁理论,首次导出了悬臂梁和自由-自由梁自由端具有附加质量的特征方程,并进而讨论了多种因素对动模量计算值的影响。此外还提出了用弯曲振动确定剪切动模量G_(12)的一般方法。最后进行了实例分析和讨论。     

DO 28飞行试验数据一致性检验

 本文研究DO28试验机飞行试验数据一致性检验及其误差校正。建立了由非线性运动学方程及内容广泛的校正环节构成的一致性检验模型,解决了大地风场重构、测量信号时间延迟估计、ψ转换及测量控制信号的校正。为DO28参数估计提供了可靠、准确的飞行试验数据。     

模态参数识别在飞行颤振试验中的应用

 本文介绍了飞机飞行颤振试验的简况、颤振试飞数据处理的特点和一些特殊要求。简要介绍了用频域参数识别方法和时域参数识别方法识别模态频率和阻尼的基本原理和基本数学模型。文中着重介绍了为解决颤振试飞中所获得的信号的信噪比差,而又要求识别的模态阻尼值的精度比较高这个矛盾和为了尽量缩短数据分析所花费的计算时间而采取的若干措施。     

不同氧化剂对丁羟(HTPB)推进剂老化性能影响的研究

本文研究了不同氧化剂对丁羟(HTPB)推进剂老化性能的影响.实验结果表明:随着推进剂老化时间的延长,最大拉伸强度增加,伸长率降低,邵氏硬度升高,失重百分数略有下降,而相对交联密度也上升.由此可以得出结论:热稳定的、产物氧化性弱的氧化剂,对于提高丁羟推进剂的老化性能是有益的.本文进一步用热重分析方法和红外光谱法对上述结果作了验证,并对丁羟推进剂的老化机理进行了初步探讨.     

分布式航空电子系统信息传输机构设计研究

 航空电子系统日益增长的复杂性使其必须走向分布式处理的道路。本文介绍一个基于1553B总线的分布式航空电子系统的实验模型——EPDAS系统,讨论了EPDAS系统信息传输机构的有关组成部分:总线通信协议、通信管理软件和总线接口,本文在分析传统的同步总线控制方式的缺点之后,提出了询问和命令/响应相结合的总线控制方式,该方式能提高总线传输的效率和实时性。在EPDAS系统的总线接口设计中,引入了流水线并行处理技术,解决了总线接口的瓶颈问题,并使之易于VLSI化;伪DMA控制的概念,使总线接口电路更加简化;共享存贮器的互连技术,具有效率高、控制简单、容易实现等优点。EPDAS系统结构合理、效率高,符合国情、适合于新一代的飞机。     

推力向量控制方案及计算

本文归纳推力向量控制的主要方案,着重介绍摆动喷管、流体二次喷射方案的计算思路和结果.摆动喷管中的流场计算要考虑导弹偏摆对所产生的惯性力的影响;所得壁面压力畸变图说明,它是一个三维流场.在摆动喷管设计中要将铰链力减至最小,流体二次喷射的侧向力通过“等效实体模型”,用爆炸波的解来计算.     

三维侧面突扩燃烧室冷态气流场的数值模拟

本文对四侧30°进气并带有进气管道和尾喷口的突扩燃烧室冷态气流场进行了数值模拟.对这种复杂非规则边界的计算区域,首次采用分段算法进行计算.结果表明:分段算法可以提高网络利用率,缩短机时,消除虚假扩散,提高计算准确度,计算结果与试验结果基本符合.     

轮盘偏心孔低循环疲劳寿命预测法

本文在系统的试验研究基础上提出了应用光滑圆棒试样的低循环疲劳断裂寿命统计数据来精确地预测轮盘偏心孔的低循环疲劳起始中值寿命和可靠性寿命(存活率p=99.9％)的方法。研究表明,对近似于单轴应力状态的轮盘偏心孔来说,其起始寿命一般只与危险点上的最大应变历程有关,而与应变梯度关系不大。研究还表明,中值寿命通常只与钢的化学成份和热处理种类有关;而可靠性寿命则与许多因素有关。     

Gravitation and celestial mechanics investigations with Galileo

The gravitation and celestial mechanics investigations during the cruise phase and Orbiter phase of the Galileo mission depend on Doppler and ranging measurements generated by the Deep Space Network (DSN) at its three spacecraft tracking sites in California, Australia, and Spain. Other investigations which also rely on DSN data, and which like ours fall under the general discipline of spacecraft radio science, are described in a companion paper by Howard et al. (1992). We group our investigations into four broad categories as follows: (1) the determination of the gravity fields of Jupiter and its four major satellites during the orbital tour, (2) a search for gravitational radiation as evidenced by perturbations to the coherent Doppler link between the spacecraft and Earth, (3) the mathematical modeling, and by implication tests, of general relativistic effects on the Doppler and ranging data during both cruise and orbiter phases, and (4) an improvement in the ephemeris of Jupiter by means of spacecraft ranging during the Orbiter phase. The gravity fields are accessible because of their effects on the spacecraft motion, determined primarily from the Doppler data. For the Galilean satellites we will determine second degree and order gravity harmonics that will yield new information on the central condensation and likely composition of material within these giant satellites (Hubbard and Anderson, 1978). The search for gravitational radiation is being conducted in cruise for periods of 40 days centered around solar opposition. During these times the radio link is least affected by scintillations introduced by solar plasma. Our sensitivity to the amplitude of sinusoidal signals approaches 10^-15 in a band of gravitational frequencies between 10^-4 and 10^-3 Hz, by far the best sensitivity obtained in this band to date. In addition to the primary objectives of our investigations, we discuss two secondary objectives: the determination of a range fix on Venus during the flyby on 10 February, 1990, and the determination of the Earth's mass (GM) from the two Earth gravity assists, EGA1 in December 1990 and EGA2 in December 1992.