脉冲发动机软隔离装置反向打开过程研究

通过显示动力学的方法,对一种软隔离装置反向打开过程进行了模拟,并通过燃气发生器-隔层试验装置,进一步验证了隔层的打开过程,模拟结果与试验结果吻合得较好,验证了计算方法的合理性。研究结果表明,脆性断裂准则可较准确地预测隔层的破坏位置和压强,同时在内压冲击载荷作用下隔层薄弱区域首先出现破裂,破裂后下隔层结构逐渐反向打开,最终端口发生严重破坏,研究结果可用于发动机隔层的初步设计。     

民机复合材料目视检查中的眼动与疲劳检测

疲劳是导致民机复合材料结构目视检查差错的重要诱因，疲劳检测对于减少人的差错，保障飞行安全具有重要意义。对基于眼动行为的疲劳度量与检测方法进行了研究，建立了民机复合材料结构目视检查实验场景，利用Tobii眼动仪提取了正常状态和疲劳状态下的目视检查眼动数据，分析了瞳孔直径、平均注视时间、平均注视频率、平均眼跳时间、平均眼跳频率、注视热点与轨迹和扫视速度等眼动行为与疲劳的关系，进而提取了能表征疲劳的瞳孔直径、平均注视时间和扫视速度3种眼动指标，以该指标构建特征向量，利用支持向量机（SVM）方法构建了目视检查疲劳检测模型。研究发现疲劳状态下的目视检查平均注视时间更长，扫视速度更慢、瞳孔直径减小，右瞳孔减小程度更大，核函数为径向基函数和高斯函数的SVM方法对疲劳的检测效果好。研究结果表明，利用SVM方法训练由瞳孔直径、平均注视时间和扫视速度构成的眼动特征向量能有效检测目视检查中的疲劳状态。     

Numerical exploration on the thermal invasion characteristics of two typical gap-cavity structures subjected to hypersonic airflow

In this paper, numerical investigation of hypersonic gas flow over two typical gap-cavity structures is carried out using all-speed preconditioned density-based solver. Such structures filled with porous seal in the gap are often present at the joint locations of control surfaces of the hypersonic vehicles. Single-domain approach is adopted to integrate the governing equations for both porous and fluid regions. The basic thermal invasion characteristic is first illustrated using the maze gap-cavity structure without sealing. Then, the influence of seal filling depth on the thermal invasion characteristic is investigated for the structure with sealing. Finally, a comparison of thermal invasion characteristics between maze and straight gap-cavity structures is performed to examine the influence of gap bending. Results show that the main source of hot airflow invading into the gap is from the millimeter scale gas layer within the boundary layer. And the invasion characteristic presents approximate stationary behavior. A primary vortex occurs in the gap adjacent to the leeward wall, which is ascribed to the impinging effect between the separate boundary flow and the windward wall. This effect is also the main driving force of thermal invasion. A treatment of filling the seal in certain depth inside the gap can significantly reduce the thermal load of seal and maintain an acceptable level of the invading mass flow rate. Additionally, it is found that the gap bending exerts a limited block effect on the thermal invasion without sealing, and this effect can be ignored with sealing. These results can provide a reference for optimizing the seal gap-cavity structure configuration.     

航空发动机整体叶盘磨料水射流开坯加工技术研究进展

整体叶盘结构是航空发动机技术发展的一个重要方向，且多采用难加工材料，如何实现整体叶盘高质高效加工是机械制造领域亟待解决的难题之一。通过高压磨料水射流（AWJ）加工技术实现整体叶盘毛坯的开坯粗加工，是一种有效缩短整体叶盘加工周期、降低昂贵铣削刀具成本、提高开坯效率的工艺手段。本文就磨料水射流加工材料去除机理、复杂曲面轨迹优化、多物理量和机械量参数组合优化和整体叶盘开坯设备概述了国内外的研究现状，在此基础上，针对当前具有复杂曲面结构的整体叶盘开坯面临的关键问题，提出了若干解决思路和技术途径，指出了高压磨料水射流在复杂曲面零件高效加工中的发展趋势。     

某型航空发动机涡轮机匣选材论证分析

以某型航空发动机高、低压涡轮机匣选材为例,对温度、强度和寿命进行了计算分析,并结合生产成本、材料供应状况和工艺成熟度,提供了涡轮机匣材料选择的方法。分析结果表明：GH4169合金比较适合作为航空发动机涡轮机匣材料。     

Material optimization: bridging the gap between conceptual and preliminary design

This paper presents a collection of tools for conceptual structure design. The underlying model is the ‘free material optimization’ problem. This problem gives the best physically attainable material and is considered as a generalization of the sizing/shape optimization problem. The method is supported by powerful optimization and numerical techniques, which allow us to work with bodies of complex initial design and with very fine finite-element meshes. The computed results are realized by composite materials. We consider a particular class of fibre-reinforced composite materials, manufactured by the so-called tape-laying technology. In the post-processing phase, stress/strain-trajectories are plotted which indicate how to place these tapes; they also show the proposed thickness of the tapes. Several examples demonstrate the efficiency of this approach to conceptual design of engineering structures.     

Microstructure and mechanical properties of hybrid fabricated 1Cr12Ni2WMoVNb steel by laser melting deposition

 Laser melting deposition was carried out to deposit a 1Cr12Ni2WMoVNb steel bar on a wrought bar of same material. Room-temperature tensile properties of the hybrid fabricated 1Cr12Ni2WMoVNb steel sample were evaluated, and microstructure, fracture surface morphology, and hardness profile were analyzed by an optical microscope (OM), a scanning electron microscope (SEM), and a hardness tester. Results show that the hybrid fabricated 1Cr12Ni2WMoVNb steel sample consists of laser deposited zone, wrought substrate zone, and heat affected zone (HAZ) of the wrought substrate. The laser deposited zone has coarse columnar prior austenite grains and fine well-aligned dendritic structure, while the HAZ of the wrought substrate has equiaxed prior austenite grains which are notably finer than those in the wrought substrate zone. Besides, austenitic transformation mechanism of the HAZ of the wrought substrate is different from that of the laser deposited zone during the reheating period of the laser deposition, which determines the different prior austenite grain morphologies of the two zones. Microhardness values of both the laser deposited zone and the HAZ of the wrought substrate are higher than that of the wrought substrate zone. Tensile properties of the hybrid fabricated 1Cr12Ni2WMoVNb steel sample are comparable to those of the wrought bar, and fracture occurs in the wrought substrate zone during the tensile test.     

导热增强型相变材料温控试验

为满足高超声速飞行器舱内温度要求,提出了在舵轴热短路区域使用相变材料进行热耗散的方案.通过开展导热增强型相变材料温控试验,获得了不同试验方案对舵轴及周围金属壳体的降温效果.结果表明,导热增强型相变材料由于良好的导热性能,能够很好地发挥相变吸热能力,对降低舵轴热短路区域的局部高温具有显著效果;金属壳体内、外同时使用低温和中温相变装置,能够将舵轴周围金属壳体温度控制在允许工作温度范围内(150℃).本研究可为飞行器舵轴温控设计提供指导.     

气体传感器的研究及发展方向

介绍了气体传感器的特性；根据气体传感器使用的气敏材料以及气敏材料与气体相互作用的效应不同，对气体传感器进行了分类；介绍了目前气敏元件的加工技术；论述了气体传感器的发展方向。     

固体发动机复合材料壳体的电子束固化

叙述了电子束固化技术在固体火箭发动机复合材料壳体工艺中的应用，讨论了该技术的优点和局限性，介绍了在航空航天其它领域内的推广情况。