Integrated optimization on aerodynamics-structure coupling and flight stability of a large airplane in preliminary design

The preliminary phase is significant during the whole design process of a large airplane because of its enormous potential in enhancing the overall performance. However, classical sequential designs can hardly adapt to modern airplanes, due to their repeated iterations, long periods, and massive computational burdens. Multidisciplinary analysis and optimization demonstrates the capability to tackle such complex design issues. In this paper, an integrated optimization method for the preliminary design of a large airplane is proposed, accounting for aerodynamics, structure, and stability. Aeroelastic responses are computed by a rapid three-dimensional flight load analysis method combining the high-order panel method and the structural elasticity correction. The flow field is determined by the viscous/inviscid iteration method, and the cruise stability is evaluated by the linear small-disturbance theory. Parametric optimization is carried out using genetic algorithm to seek the minimal weight of a simplified plate-beam wing structure in the cruise trim condition subject to aeroelastic, aerodynamic, and stability constraints, and the optimal wing geometry shape, front/rear spar positions, and structural sizes are obtained simultaneously. To reduce the computational burden of the static aeroelasticity analysis in the optimization process, the Kriging method is employed to predict aerodynamic influence coefficient matrices of different aerodynamic shapes. The multidisciplinary analyses guarantee computational accuracy and efficiency, and the integrated optimization considers the coupling effect sufficiently between different disciplines to improve the overall performance, avoiding the limitations of sequential approaches utilized currently.     

大振幅非定常实验数学模型与动导数仿真实验

本文通过对大振幅非定常实验数据进行处理,采用Ｄｕｈａｍｅｌ积分方法,可获取模型迎角按任意 规律变化时的非定常空气动力,并在此基础上,发展了一种从大振幅实验获得小振幅导数的新方法。     

FEM Analysis of Spring-backs in Age Forming of Aluminum Alloy Plates

The age forming technology, characterized by huge spring-backs, has been developed to manufacture large integral wing-skin panel parts, which necessitates devising a method of predicting spring-backs. A 7B04-T7451 aluminum alloy creep test in tension is accomplished at 155 ℃, and the creep curves are obtained. The material constants of the mechanism-based creep constitutive equations are determined through experiments. The age forming process and the spring-backs of 7B04 aluminum alloy plates are analyzed using the commercial finite element software ABAQUS. The effects of plate thickness and forming time on spring-backs are researched. The spring-backs decrease with the increase of plate thickness and forming time. The test results verify the reliability of the finite element method （FEM） analysis.     

三维超声速混合层内标量混合的大涡模拟

对三维对流马赫数0.62的超声速混合层流动的标量混合进行大涡模拟, 控制方程对流项采用五阶精度的WENO格式求解, 小尺度涡的作用采用一方程LDKM亚格子模型处理, 过滤后的组分方程中的亚格子组分对流通量采用梯度扩散模化.模拟得到了混合层流场大尺度拟序结构以及标量场的演化过程, 研究表明标量混合过程受混合层内涡系演化所控制, 标量场具有明显的三维特征.模拟得到的速度、组分及其脉动的统计时均结果和实验结果相符较好.      

温度载荷下装药内外径比和长径比对结构完整性影响的规律研究

在固体火箭发动机装药设计中通常将药柱的外径与内径之比定义为m数(m=R/r)为研究装药设计参数m数和药柱长径比在温度载荷下对装药结构完整性的影响, 采用基于Total Lagrangian方法的热粘弹性大变形增量本构关系, 通过选取9种m数以及8种药柱长径比, 共72个计算模型, 对装药结构完整性进行了计算, 结果表明温度载荷下药柱最大Von Mises等效应力、应变值受药柱m数以及长径比共同影响.并得出当长径比大于3时, 药柱最大等效应力、应变值主要取决于m数的结论.      

欠膨胀椭圆射流的流动结构

为了探讨超声速欠膨胀椭圆射流的流动特征,采用大涡模拟（LES）方法与高精度混合格式对出口压力比N分别为14、24、40的欠膨胀椭圆射流流场结构进行数值模拟。结果清晰描述了欠膨胀椭圆射流的三维(3 D)结构特征与发展规律,并分析了因喷嘴方位曲率不一致而导致长轴与短轴平面上激波结构出现差异的原因。另外,结果还发现:当N为24时,短轴平面上射流域内的激波结构已由正规反射转变为马赫反射,但长轴平面上仍维持正规反射,而当N为40时,长轴与短轴平面上的激波结构均为马赫反射结构,由此可知喷嘴方位曲率变化越平缓,马赫反射形成所需的出口压力比越大。      

压气机叶栅端壁叶尖涡系结构非定常特性研究

为了研究压气机带间隙平面叶栅近失速工况下叶尖涡系结构特点以及其非定常流动特性,本文采用大涡模拟(Large eddy simulation,LES)方法对典型叶栅进行数值计算并结合Q准则分析叶尖涡系结构特点,探索流动规律及叶尖涡系耦合过程。研究表明:与额定工况相比,近失速工况叶尖流场更为复杂,并通过大涡模拟观察到了次泄漏涡的存在;额定工况下泄漏涡不发生破碎,主次泄漏涡在近失速条件下均发生破碎,破碎后形成的低能流体与尾缘分离涡是造成叶尖堵塞及损失的主要原因;次泄漏涡在不同时刻生成点位置及与弦长夹角周期性变化,次泄漏涡的摆动与叶尖角区分离涡团的周期性脱落是叶尖非定常性的主要原因。     

大入射余角实测高分辨 海杂波数据幅度统计特性

基于Ku波段高分辨大入射余角(擦地角)海杂波数据,采用瑞利分布、韦布尔分布、对数正态分布、K分布和KK分布进行仿真,并与实测数据对比,分析了这些分布方式的拟合效果。结果表明,海杂波的幅度在大入射余角情况下基本还是逼近瑞利分布的,海杂波在某些距离单元上的幅度分布曲线尾部偏离瑞利分布,此时K和KK分布可在拖尾处达到更好的拟合效果。     

对我国商业航天测控管理有关问题的初步探讨

国际商业航天的蓬勃发展带动了国内商业航天的兴起。以实现商业卫星高效便捷管理为目的,调研了国内外商业航天与商业航天测控的发展现状,分析了国外商业航天以及商业航天测控发展对我国商业航天测控管理的有关启示,得出了测控管理多元化大势所趋、适度鼓励商业航天测控发展势在必行等结论。同时,对我国商业航天测控管理中加强航天立法、探索商业航天测控管理新模式、加强商业卫星管理服务等问题进行了初步探讨,建议从国家层面、行业规范层面制定航天法规,卫星任务中心应支持对外联网,并加强商业航天测控地面站的国际合作,从而提高商业卫星频率、轨位、空间目标编目、发射与回收等管理服务能力。     

波音公司生产性物流运输研究

"主制造商-供应商"模式下民机研制的全球化程度越来越高,为了完成民机产品的最终总装,波音、空客需要将来自全球各地的零部件运输到相应的部段装配线,完成部段装配后还需将其进一步运送至总装厂。供应网络的全球化加上主制造商自身工厂分布的分散性,使得民机研制过程中零部件的运输工作变得更为复杂和难以控制。通过调研分析波音公司在民机研制过程中的生产性物流运输业务运作模式,总结其物流运输业务的运作经验,以期有所借鉴。