新的解跨音速Euler方程的隐式杂交方法

 本文提出一个新的杂交格式,它由Jameson-Turkel LU分解法和Harten TVD（total variation diminishing）格式的修正数值通量耦合而成。LU分解用于Euler方程隐式部分的离散化而Harten的数值通量控制所谓的稳态解残差。精心构造LU算子,可使矩阵算子L和U很容易逐点推进求逆;以Harten的数值通量计算杂交格式右边的通量,这样做在a=1/2的条件下,可保证收敛的稳态解具有二阶精度并能高分辨率地捕获激波。数值实验表明,本文格式对于稳态计算是有生命力的并能保证较高的激波分辨率。     

LY12CZ铝合金铆接件微动损伤防护技术研究

 本文详细地分析了LY_(12)CZ铝合金铆接件微动损伤的微观特征以及各种搭接表面处理方法对疲劳强度的影响。试验结果表明:对搭接表面采用恰当的处理方法,铆接件的疲劳寿命一般均有不同程度的提高,其中,胶铆结构的采用是防止铆接件产生微动损伤的有效措施。当轴向交变应力σ_(max)=125MPa以下时,胶铆试件的疲劳寿命比干涉铆接的疲劳寿命提高60％以上。     

声处理蜂窝夹层结构在飞机座舱降噪设计中的应用

 本文简要介绍了在螺旋桨飞机座舱降噪设计中采用的蜂窝刚度处理技木。通过对蜂窝夹层结构板的声透射理论分析,阐明了利用这种降噪处理方法改善低频螺旋桨飞机座舱噪声环境的原理;给出了机身侧壁壁板试件经过蜂窝刚度处理前后的隔声量试验结果。通过处理前后两种状态下隔声量曲线的比较,表明蜂窝刚度处理对改善机身侧壁壁板低频隔声量的效果。     

二维机翼二自由度跨音速颤振分析

 <正> On the assumption that airfoils take small amplitude ha-rmonic oscillating and middle reduced frequency, the two-dimensional, inviscid, small-disturbance nonlinear unsteady transonic flow equation can be split into two parts. One is the nonlinear steady small-disturbance equation, the other is the time-linearized unsteady small-disturbance equation. The steady equation is solved by Carlson code. The unsteady equation is solved by integral method. The standard v-g method is used to solve the flutter eigenvalue equations. A transonic flutter analysis is performed for a NACA 64A006 airfoil with pitching and plunging degrees of freedom.The Mach numbers considered are 0.7, 0.8, and 0.85. The aerodynamic coefficients are obtained by the above method. For each Mach number, the flutter speed and the corresponding flutter reduced frequencies are achieved by varying the airfoil-airmass ratio, plunge-pitch frequency ratio. The results are compared with other computational method and good agreement has been observe     

激光辐照强化技术的实验研究

 本文介绍了激光辐照强化技术在材料、结构方面的研究概况。在材料激光辐照参数优选的基础上,对Y7机长桁接头进行了辐照处理,并进行了模拟疲劳实验,研究了辐照参量对疲劳寿命的影响。试验结果表明辐照强化处理能显著地提高构件的疲劳寿命。     

分枝模态综合法的逆问题

 本文基于李兹分析论述了分枝模态综合法的逆问题,即结构的一个分枝系统的模态特性如何利用结构和其它分枝系统的模态特性而识别出来。其分析方法可应用于结构动态设计和结构模型修改问题。     

计算机模拟铰接式直升机的外挂施工

为了给直升机施工的安全分析提供理论基础和求解非线性外挂直升机运动方程,本文提出了用计算机模拟直升机外挂飞行的方法。所用直升机运动方程模拟程序采用美国宇航局兰利研究中心发布的铰接式单旋翼直升机模拟程序。期望航迹及外挂载荷的模拟,根据航迹及载荷反求操纵输入及配平参数的方法和运动方程的积分等将由本文给出。     

经营目标与产权结构

本文从产业组织理论出发,以企业产权结构的变革为前提,阐述和讨论了H—型、U—型和M—型股份制企业经营目标和行为目标的变异。     

带有前缘气膜冷却燃气轮机叶片的气热耦合研究(英文)

使用气热耦合数值计算方法对带有"淋浴喷头"式前缘气膜冷却的C3X燃气轮机叶片进行数值模拟。通过对使用不同湍流模型的计算结果与实验测量值进行对比,使用转捩模型能够比较准确的模拟带有气膜冷却射流的边界层内的流动和传热过程。气膜冷却射流在叶片吸力面上游层流边界层区域内表现出比较明显的三维湍流特性,但在吸力面下游边界层转捩为湍流以后,湍流使得气膜冷却射流与主流燃气掺混过程加速而使其三维流动特性迅速消失;在吸力面由于边界层流动始终为层流状态,冷却射流与主流掺混较缓慢而使其仍能保持较强的三维湍流特性。边界层内由高温燃气与被冷却叶片之间温度差形成的温度梯度有益于增强边界层流动的稳定性。     

Theory of Economic Life Prediction and Reliability Assessment of Aircraft Structures

The theory of economic life prediction and reliability assessment of aircraft structures has a significant effect on safety of air-craft structures.It is based on the two-stage theory of fatigue process and can guarantee the safety and reliability of structures.According to the fatigue damage process,the fatigue scatter factors of crack initiation stage and crack propagation stage are given respectively.At the same time,mathematical models of fatigue life prediction are presented by utilizing the fatigue scatter factors and full scale test results of aircraft structures.Furthermore,the economic life model is put forward.The model is of sig-nificant scientific value for products to provide longer economic life,higher reliability and lower cost.The theory of economic life prediction and reliability assessment of aircraft structures has been successfully applied to determining and extending the structural life for thousands of airplanes.