基于ERSM涡轮盘径向变形的非线性动态概率分析

为了准确设计高压涡轮盘和叶尖间隙,从概率的角度进行了涡轮盘径向变形的分析。介绍了高精度高效率的非线性动态概率分析的极值响应面方法 (Extremum Response Surface Method,ERSM),并建立了其数学模型。考虑材料属性和边界条件的非线性,以及热载荷和离心载荷的动态性,基于ERSM对涡轮盘径向变形进行了非线性动态概率分析,得到了输入输出参数的分布特征和影响涡轮盘径向动态变形的主要因素。最后,通过方法比较,验证了ERSM在保证计算精度的前提下能大大提高计算速度,节约计算时间,改善计算效率。为进行更有效的涡轮盘设计和优化,改善叶尖间隙设计和控制的合理性提供了有效依据。     

3D打印骨架增强石蜡燃料燃烧机理实验研究

针对固-液混合火箭发动机中石蜡基固体燃料机械性能差的问题,使用3D打印聚合物骨架镶嵌石蜡的方法增强了石蜡基燃料的结构强度,分析了骨架增强石蜡燃料在直/旋流喷注下的燃烧机理。通过对七种骨架材料进行SEM扫描、力学、热力学分析和纯氧条件下的燃烧试验,获得了不同骨架材料的微观表面结构、机械性能、热分解性能以及在纯氧环境下的燃烧性能;使用直/旋流固-气掺混燃烧试验系统,开展了螺旋型和六角型骨架增强石蜡燃料的燃烧试验,并与ABS固体燃料进行了对比。结果显示,在多种骨架材料中,ABS材料加工性能、机械性能及热分解性能良好;燃烧过程中,骨架增强石蜡燃料结构稳定性良好,石蜡液滴主要出现在石蜡-骨架交界处;旋流喷注和螺旋型骨架可促进石蜡液滴的夹带现象;在直流喷注工况中,骨架的凹槽结构增加了燃料与氧化剂的接触面积,尾部骨架结构具有稳焰作用,可促进后燃烧室的掺混燃烧;石蜡燃料和骨架燃速差异较大,发动机内弹道性能可能受此影响。     

不同型线结构船艏表面压力特性对比实验研究

为优选船艏结构型线方案,在风洞中针对三个在结构型线上仅有细微差别的船艏方案进行表面压力特性对比测试。实验获得了各型线方案模型表面压力空间分布特性和压力脉动特性,并通过表面压力特性的综合对比进行了结构型线评估,为船艏的结构型线设计提供直接的技术依据。     

Reconfigurable Flight Control Design for Combat Flying Wing with Multiple Control Surfaces

With control using redundant multiple control surface arrangement and large-deflection drag rudders,a combat flying wing has a higher probability for control surface failures.Therefore,its flight control system must be able to reconfigure after such failures.Considering three types of typical control surface failures(lock-in-place(LIP),loss-of-effectiveness(LOE) and float),flight control reconfiguration characteristic and capability of such aircraft types are analyzed.Because of the control surface redundancy,the aircraft using the dynamic inversion flight control law already has a control allocation block.In this paper,its flight control configuration during the above failures is achieved by modifying this block.It is shown that such a reconfigurable flight control design is valid,through numerical simulations of flight attitude control task.Results indicate that,in the circumstances of control surface failures with limited degree and the degradation of the flying quality level,a combat flying wing adopting this flight control reconfiguration approach based on control allocation could guarantee its flight safety and perform some flight combat missions.     

着陆姿态对地外天体表层采样的影响研究

表层采样技术是获得地外天体特性的重要手段,是完成地外天体采样任务的一项关键技术。文章结合4自由度表层采样装置的特点,建立了表层采样装置的逆运动学模型,分析了极限着陆姿态下表层采样装置安装位置在当地参考坐标系中的变化,并针对一次封装与二次封装过程中表层采样装置的位置和姿态要求,明确了末端采样器姿态补偿方法,提出了着陆姿态对表层采样影响的分析算法。仿真结果表明,该算法能有效分析着陆姿态对表层采样的影响,可为表层采样装置适应性设计提供支持。     

嵌金属丝推进剂燃烧起始阶段增速特性研究

考虑了使用嵌金属丝装药的发动机工作过程中的多种因素,建立了金属丝与药柱、燃气间相互作用的控制方程组,并对方程组进行了数值求解,得到了嵌金属丝推进剂在燃烧起始阶段,增速比随时间的详细变化过程。结果表明,金属丝的热扩散率、熔点、直径和黑度以各自不同的方式影响金属丝的增速效果,熔点相对较低的金属丝可能会在内弹道曲线的初始阶段形成一个轻微的压强峰,固有燃速较低、着火温度较低的推进剂对嵌入金属丝较为敏感。文中数值方法计算量小,结果可靠,适于工程应用。     

多跑道内水平障碍物限制面边界确定方法

对机场多跑道系统的障碍物限制面——内水平面的边界确定方法进行了系统研究。通过将N条（N≥3）复杂构形跑道简化为2N个点集，根据国际民航组织内水平面障碍物限制面形成原理并利用多边形凹凸性几何特征，给出了内水平面边界的确定方法和计算步骤。     

用大面积源检定核应急机载/车载伽玛能谱仪

人工核素大面积源标准是核工业航测遥感中心等单位经过十余年研究建立的新型计量保障标准,使用该标准,可对监测核应急伽玛辐射环境的机载/车载伽玛能谱仪进行检定.使用大面积源标准检定,可以有效地弥补因机载/车载伽玛能谱仪系统的角响应影响因素复杂而难于模拟计算的缺陷,为监测核应急伽玛辐射环境的机载/车载伽玛能谱仪提供了量值传递的保障.本文介绍了大面积源检定的原理和技术方法.     

A theoretical model of semi-elliptic surface crack growth

A theoretical model of semi-elliptic surface crack growth based on the low cycle strain damage accumulation near the crack tip along the cracking direction and the Newman–Raju formula is developed. The crack is regarded as a sharp notch with a small curvature radius and the process zone is assumed to be the size of cyclic plastic zone. The modified Hutchinson, Rice and Rosengren(HRR) formulations are used in the presented study. Assuming that the shape of surface crack front is controlled by two critical points: the deepest point and the surface point.The theoretical model is applied to semi-elliptic surface cracked Al 7075-T6 alloy plate under cyclic loading, and five different initial crack shapes are discussed in present study. Good agreement between experimental and theoretical results is obtained.     

Analysis of crack opening stresses for center- and edge-crack tension specimens

Accurate determination of crack opening stress is of central importance to fatigue crack growth analysis and life prediction based on the crack-closure model. This paper studies the crack opening behavior for center- and edge-crack tension specimens. It is found that the crack opening stress is affected by the crack tip element. By taking the crack tip element into account, a modified crack opening stress equation is given for the center-crack tension specimen. Crack surface displace- ment equations for an edge crack in a semi-infinite plate under remote uniform tension and partially distributed pressure are derived by using the weight function method. Based on these displacements, a crack opening stress equation for an edge crack in a semi-infinite plate under uniform tension has been developed. The study shows that the crack opening stress is geometry-dependent, and the weight function method provides an effective and reliable tool to deal with such geometry depen- dence.