模拟月尘对巡视器车轮轮轴材料的磨损试验研究

文章以CE-3巡视器车轮轮轴为研究对象,利用北京卫星环境工程研究所的月尘环境模拟器、摩擦磨损试验机以及自行研制的模拟月尘,对车轮轮轴主要材料进行了磨损试验研究。试验样品为轮轴常用的铝合金、聚四氟乙烯及轴承钢。文章分析了试验前后样品的表面形貌,采用测试系统获得了轮轴材料在不同试验条件下的摩擦系数曲线,采用电子天平测量了材料的质量损失;分析了真空、大气、有无月尘等试验条件以及材料本身在磨损试验中的效应。研究结果可为月面巡视器等月面应用设备的研制提供可借鉴的信息。     

并联硅基扩缩微通道热沉强化传热特性

采用去离子水作为冷却工质,实验研究了并联硅基扩缩微通道热沉内的流体流动与强化传热特性.基于微尺度强化传热机理,设计加工了两种并联硅基扩缩微通道热沉.通过测量流体的体积流量、进出口压降与温度、热沉底面加热膜温度,并以传统矩形直通道热沉为参照,获得了并联硅基扩缩微通道热沉在恒热流边界条件和不同体积流量工况下流体流动与对流传热特性参数.结果显示:相对于矩形直通道,并联硅基扩缩微通道热沉的表面传热系数可提高12.5%~85.1%,但摩擦因数只增加了-9.2%~31.4%.表明并联硅基扩缩微通道热沉具有优越的强化传热特性.      

火箭深弹水下减阻技术研究

基于Fluent软件,对火箭深弹的水下减阻技术进行了研究。提出了火箭深弹中部补气的减阻方式。通过对下潜速度和通气量2个影响因素的分析,得到了火箭深弹在8～100 m/s速度范围的流场计算结果。计算结果表明,中部补气能有效地减小阻力,最大减阻效率达到25%;火箭深弹在水中所受阻力随通气量的增大而减小,在通气量相同的条件下,减阻效率随下潜速度的减小而增大。计算结果与实验结果基本一致。     

高压载荷下旋转动密封结构转动力矩分析

对于高压下的旋转密封结构,开展O型橡胶圈的摩擦力矩影响因素分析,同时对摩擦力矩的近似解析算法和有限元算法进行计算对比,分析近似解析算法方法产生误差的原因,并利用地面压力容器试验装置进行计算结果的验证,得出近似解析算法仅适用于低压环境,而有限元计算结果对高低压环境均适用。     

隐身舰载战斗机气动力设计关键技术

围绕隐身舰载战斗机气动力设计中的关键技术问题,深入梳理了有益的工程设计经验,从多目标约束下的起降增升设计、跨超声速精细化减阻设计、全机均衡减载设计等3个方面,阐述了气动力设计在性能、操稳、重量、隐身等多专业强约束下的窄域设计方法。相关分析表明：采用机翼后缘简单襟翼的设计方式、结合机翼三维型面弯扭设计与舵面使用策略优化,能够满足强隐身约束下舰载战斗机的起降升力需求;合理配置座舱位置以及后机身上表面的激波压缩/膨胀波系、优化进气道溢流吸力矢量方向等,能够在不降低机身容积的前提下,有效降低机身阻力;利用机身下表面与拦阻钩舱门区的修型进行机身反弯设计,能够实现严重载荷状态下的平尾减载。     

Whole-process design and experimental validation of landing gear lower drag stay with global/local linked driven optimization strategy

Landing gear lower drag stay is a key component which connects fuselage and landing gear and directly effects the safety and performance of aircraft takeoff and landing. To effectively design the lower drag stay and reduce the weight of landing gear, Global/local Linked Driven Optimization Strategy (GLDOS) was developed to conduct the overall process design of lower drag stay in respect of optimization thought. The whole-process optimization involves two stages of structural conceptual design and detailed design. In the structural conceptual design, the landing gear lower drag stay was globally topologically optimized by adopting multiple starting points algorithm. In the detailed design, the local size and shape of landing gear lower drag stay were globally optimized by the gradient optimization strategy. The GLDOS method adopts different optimization strategies for different optimization stages to acquire the optimum design effect. Through the experimental validation, the weight of the optimized lower dray stay with the developed GLDOS is reduced by 16.79% while keeping enough strength and stiffness, which satisfies the requirements of engineering design under the typical loading conditions. The proposed GLDOS is validated to be accurate and efficient in optimization scheme and design cycles. The efforts of this paper provide a whole-process optimization approach regarding different optimization technologies in different design phases, which is significant in reducing structural weight and enhance design precision for complex structures in aircrafts.     

基于阻力跟踪的火星大气进入段非线性预测制导律设计

针对火星探测任务大气进入段的高精度着陆问题,提出一种基于阻力跟踪的非线性预测制导策略。基于火星探测器大气进入段的三维运动模型,综合考虑探测器气动参数摄动、火星大气密度摄动、外部扰动以及进入时刻状态初值不确定性,设计了基于优化思想的非线性预测制导律,并对所提出的制导方法进行仿真验证。仿真结果表明:非线性预测制导律在满足控制约束的条件下可以获得较高的着陆精度。     

Comparative study of two lay-up sequence dispositions for flexible skin design of morphing leading edge

Morphing leading edge has great potential for noise abatement and aerodynamic efficiency improvement. The drooping effect is realized by bending of the flexible skin which encloses to form the leading edge. Since the flexible skin is often made of composite laminates of Glass Fiber Reinforced Plastics (GFRP), the lay-up sequences have become the determinant, which affects not only the morphing quality but also the manufacturing complexity. Two optimizing methods of lay-up sequences are comparatively studied. In the first method, the laminal quantities in 0°, ±45° and 90° vary independently, while in the second one, the concept of isotropic laminate unit [0/45/−45/90]s is employed and the unit quantity is the unique variable. Final evaluation demonstrates that for both methods there is insignificant impact to the overall morphing quality; however, specific concern is equally necessary for these two methods to the tip of the leading edge where the skin is at its minimum thickness and bears the most severe bending deformation. In terms of computational efficiency and post-processing labor, the second method has better performance.     

铝和不锈钢FSW对搭接接头界面结构及性能研究

采用搅拌摩擦焊接方法,设计了基于“差高 偏置”的对搭接接头,对厚度为4　mm的 5A06铝合金和厚度为2　mm的316L不锈钢进行了搅拌摩擦焊接(Friction stir welding, FSW)焊接试验。通过观察焊缝金相形貌发现,焊接界面光滑平整,没有形成Hook钩,在焊缝靠近界面位置形成了钢颗粒增强铝基复合组织和河流状花样组织结构。通过SEM观察,铝 钢之间形成了一层厚度约为3　μm的中间过渡层。显微硬度及拉伸测试结果表明,过渡层的显微硬度较高,接头的拉伸强度达到了铝合金母材强度的89.7%。     

航天领域常用聚四氟乙烯性能试验研究

聚四氟乙烯因其具有优异的特性,在航天领域有着广泛的应用。文章对SFB-2、M-12、M-111、4FT-6这4种航天领域常用聚四氟乙烯材料的摩擦性能和压缩变形特性进行试验研究:50 N载荷下它们的磨损率分别为1.21×10-4、1.39×10-4、1.32×10-4、1.19×10-6 mm3/(N·m);而13.7 MPa压缩载荷作用下的压缩变形量依次为7.0%、6.1%、3.3%、3.3%。表明不同厂家、不同牌号聚四氟乙烯的摩擦性能和压缩变形特性存在显著差异,在进行产品设计、材料选型时必须因材施用。