微纳米尺度流动实验研究的问题与进展

微纳米实验流体力学研究的流动特征尺度在1mm～1nm范围,处于宏观流动到分子运动的过渡区。连续介质力学与量子力学这两个经典理论的衔接,提出了诸如连续性假设适用性、边界滑移等基本理论问题。同时从微纳米尺度研究界面处液/固/气的耦合,化学、电学性质对流动的影响值得关注。微纳米实验测量仪器融入了力、电等测量手段,要求测量空间精度达到nm量级,力的测量精度达到pN,时间分辨率达到ns。本文围绕连续性假设适用性、边界滑移、微纳米粒子布朗运动及微尺度涡旋测量等问题,介绍了 Micro/Nano PIV、示踪粒子流场显示等技术应用于微纳流场观测的进展与难点。目前微纳米流动测量仍然沿着经典流体力学测量“小型化”的思路开展,而纳尺度的测量期待着新的实验方法与技术的提出。     

Aeroelastic two-level optimization for preliminary design of wing structures considering robust constraints

An aeroelastic two-level optimization methodology for preliminary design of wing struc- tures is presented, in which the parameters for structural layout and sizes are taken as design vari- ables in the first-level optimization, and robust constraints in conjunction with conventional aeroelastic constraints are considered in the second-level optimization. A low-order panel method is used for aerodynamic analysis in the first-level optimization, and a high-order panel method is employed in the second-level optimization. It is concluded that the design of the abovementioned structural parameters of a wing can be improved using the present method with high efficiency. An improvement is seen in aeroelastic performance of the wing obtained with the present method when compared to the initial wing. Since these optimized structures are obtained after consideration of aerodynamic and structural uncertainties, they are well suited to encounter these uncertainties when they occur in reality.     

新型免抬式电动刀架的研究

本文介绍了一种ＣＮＣ机床新型免抬式电动刀架的机械结构及控制电路。该电动刀架采用梯形螺柱螺套副升降机构，可使刀架转位分度时无需抬起上刀体。刀架转位分度采用机－ 电结合的方法，即先在控制电路中使用霍尔元件进行粗定位，再在机械上采用三齿盘实现精定位。     

由Ω子群所决定的格序群的结构

设Ｇ是一个格序群，П（Ｇ），П（ｍ（Ｇ），Ｐ（Ｇ），Ｃ（Ｇ）分别是Ｇ的素子群，极小素子群，极子群，凸１－子群集合，Ω（Ｇ）是Ｐ（Ｇ）在Ｃ（Ｇ）中生成的闭子格。Ω（Ｇ）的元素称为Ｇ的Ω－子群。     

Assessment on critical technologies for conceptual design of blended-wing-body civil aircraft

Civil aviation faces great challenges because of its robust projected future growth and potential adverse environmental effects. The classical Tube-And-Wing(TAW) configuration following the Cayley's design principles has been optimized to the architecture's limit, which can hardly satisfy the further requirements on green aviation. By past decades' investigations the BlendedWing-Body(BWB) concept has emerged as a potential solution, which can simultaneously fulfill metrics of noise, emission and fuel burn. The purpose of the present work is to analyze the developments of critical technologies for BWB conceptual design from a historical perspective of technology progress. It was found that the high aerodynamic efficiency of BWB aircraft can be well scaled by the mean aerodynamic chord and wetted aspect ratio, and should be realized with the trade-offs among stability and control and low-speed performance. The structure concepts of non-cylinder pressurized cabin are of high risks on weight prediction and weight penalty. A static stability criterion is recommended and further clear and adequate criteria are required by the evaluations of flying and handling qualities. The difficulties of propulsion and airframe integration are analyzed. The energy to revenue work ratios of well-developed BWB configurations are compared,which are 31.5% and 40% better than that of TAW, using state-of-art engine technology and future engine technology, respectively. Finally, further study aspects are advocated.     

机匣沟槽对微型轴流涡轮叶尖泄漏流动的影响

本文通过对某微型涡喷发动机的单级轴流式涡轮进行机匣设计,采用剪切应力输运(SST)模型求解定常黏性雷诺平均Navier-Stokes方程,研究了不同机匣沟槽结构对其叶尖泄漏流动的影响。计算结果说明：当全机匣沟槽结构的叶顶浸入沟槽即d/c＞1.0时,封严效果较好;相较于全机匣沟槽结构,后开式机匣沟槽结构的封严效果更好, 随着沟槽前缘间隙的增大,封严效果减弱;沟槽深度a/c=1时,封严效果最佳,即泄漏流明显减弱,同时效率减小量较小。     

铝合金锻件重复淬火保温时间对组织性能的影响

分析了铝合金锻件重复淬火保温时间的长短及其组织性能的影响情况。根据大量的试验数据,证实了重复淬火保温时间及时效保温时间的长短对锻件性能的直接影响,并以此确定了合理的工艺参数。     

可伸缩挠性结构的稳定性研究

研究了一类可伸缩挠性梁结构的稳定性。主要结论有：一般可伸缩挠性梁结构的动力学可由刚体姿态运动、挠性体振动和梁伸缩运动相耦合的混合偏微分方程和常微分方程描述;结构振动与转动能量的耗散与积聚取决于梁的伸缩运动,在伸展过程中系统的能量被耗散,在收缩过程中系统能量被积聚,在平台保持过程系统能量维持不变。因此,梁的伸展过程是稳定的,梁的收缩过程是不稳定的,而平台保持过程是临界稳定的。     

火箭结构估重与总体优化设计的数字化实现及应用

火箭新型号总体方案论证时,一般借鉴国内外相近规模和相同推进剂火箭的结构系数进行类比确定子级结构系数,按照比例系数分配贮箱和壳段等部段的质量,但该质量分配不能反映载荷对结构设计的影响,在细化迭代设计中易造成方案无法闭环,导致设计工作反复。为了加快总体方案论证,提出一种基于载荷的箭体结构快速估重方法,开发形成结构估重数字化模块并嵌入总体设计平台。应用案例表明,提出的数字化估重平台能够有效提高估重精度,同时显著缩短论证周期,兼具总体方案比较和优化、全箭质量管理等功能,能有效降低方案推翻重新设计的风险,在新型号总体方案论证中发挥了重要作用。     

可重复使用航天器耐高温复合材料结构设计技术

针对未来可重复使用航天器需求,本文首先简要分析了国外典型重复使用航天器耐高温复合材料结构设计技术应用进展与特点,包括美国X系列、追梦者飞行器。然后从结构选材、设计和分析等方面,论述了可重复使用航天器大量应用先进耐高温树脂基复合材料整体结构相关的主要工程技术现状和发展方向,从工程应用角度为未来可重复使用航天器结构研制提供理论分析。最后介绍了未来需开展的可重复使用航天器耐高温复合材料结构设计技术重点研究内容。