气膜出流条件下回转通道流动特性的实验研究

采用实验方法研究气膜出流条件下带肋回转通道流动特性,其中回转通道为带90°直肋变截面通道。根据研究问题的特点,利用单元分析方法,定义了壁面有效压力及单元有效压力系数。结果表明:通道出口段存在气膜出流与无气膜出流情况相比出口段有效压力分布发生变化,并且使整个通道的流阻下降。影响流动的主要因素是通道的阻塞比、长径比、宽高比、气膜出流比和进口雷诺数。     

非定常尾迹对叶栅气膜冷却效率的影响

通过实验的方法研究了非定常尾迹对气膜冷却效率的影响,在平面叶栅实验台上安装了尾迹发生器,用来产生非定常尾迹。用热电偶测量了雷诺数5 04×104,1 08×105,斯托劳哈儿数0 04～0 18时气膜的绝热冷却效率,通过实验数据分析了非定常尾迹的宽度和扫过频率对气膜绝热冷却效率的影响。发现非定常尾迹通过两方面来影响气膜冷却效率,一方面是通过对气膜层的扰动来降低气膜冷却效率,另一方面是通过改变局部吹风比来影响气膜冷却效率。     

气膜孔布局对前缘气膜冷却效率影响的实验

针对叶片前缘结构的特点,建立了前缘气膜冷却实验台,实验模型由半圆柱面和两个平板组成,在距离滞止线2倍气膜孔直径距离位置布置了1排气膜孔。主流在前缘的湍流度为8%,二次流和主流密度比为1.5,动量比变化范围为0.5~4,分析了在不同动量比下气膜孔间距和径向角变化对径向平均气膜冷却效率的影响。径向角分别为0,°45,°65,°孔间距与孔径的比分别为2,3,4。研究结果表明,随着孔间距的增加,径向平均冷却效率逐渐降低。径向角对径向平均冷却效率的影响非常复杂。     

红外可见兼容隐身薄膜的制备与性能

采用多弧离子镀制备了多彩Al/TiNO(掺氮TiO2)薄膜,利用SEM观察了薄膜的表面、断面形貌,并测量了其膜厚.采用XRD研究了薄膜的相结构.利用紫外一可见分光光度计研究了TiNO膜的可见光谱特性,用红外比辐射率测量仪测量了样品的红外发射率.结果表明:在不改变Al箔在8～14 um波段低红外发射率的情况下,实现了其物理着色.所得薄膜为锐钛矿型TiO2结构,薄膜表面平整、致密,结合力较好.TiNO薄膜呈明显柱状生长,薄膜试样表面未出现明显缺陷,薄膜表面致密,柱状颗粒生长完好.TiNO薄膜的沉积速率达120 nm/min.     

低红外发射率迷彩填料的制备及光谱特性

采用化学液相沉淀法获得了具有核层结构的 Al/ SiO2/Fe2O3颜料,在基本不改变Al粉在8～14靘波段红外发射率的情况下,实现了片状Al粉的物理着色.分析了正硅酸乙酯(TEOS)水解一缩聚反应及氯化铁水解反应机理,并以此制备了Al/SiO2/Fe2O3三层结构的复合粒子,研究了包覆的工艺条件.通过扫描电镜、能谱、X射线衍射、紫外-可见光吸收谱等方法对包膜后的片状Al粉粒子进行了分析与表征.实验结果表明,通过液相沉积法在Al粉表面成功包覆了SiO2/Fe2O3薄膜,得到了低红外发射率的迷彩Al粉颜料.     

孔间距和前倾角对进出口扩张形气膜孔流量系数的影响(英文)

Discharge coefficients of 3-in-1 hole of three inclination angles and three spacing between holes are presented which described the discharge behavior of a row of holes. The inlet and outlet of the 3-in-1 hole both have a 15° lateral expansion. The flow conditions considered are mainstream turbulence intensities and density ratios of secondary flow to mainstream. The momentum flux ratios varied in the range from 1 to 4. The comparison is made of the discharge coefficients of three shaped holes to find an optimal hole with low flow loss. The results show that the discharge coefficients of 3-in- 1 hole are highest in three shaped holes and therefore this article is focused on the measurements of discharge coefficients of 3-in-1 hole for various geometries and aerodynamic parameters. The measured results of 3-in-1 hole indicate that turbulence intensities, density ratios and momentum flux ratios have weak influence on discharge coefficients for inclination angle of 20°. The high turbulence intensity yields the small discharge coefficients for inclination angle of 45° and 90°. The increased both momentum flux ratios and density ratios lead to the increased discharge coefficients for inclination angle of 45° and 90°. The increased inclination angle causes the rapidly increased discharge coefficients. There is a weak dependence of discharge coefficients on hole pitches.     

Aviation-oriented Micromachining Technology-Micro-ECM in Pure Water

This article proposes a precise and ecofriendly micromachining technology for aerospace application called electrochemical machining in pure water （PW-ECM）. On the basis of the principles of water dissociation, a series of test setups and tests are devised and performed under different conditions. These tests explain the need for technological conditions realizing PW-ECM, and further explore the technological principles. The results from the tests demonstrate a successful removal of electrolytic slime by means of ultrasonic vibration of the workpiece. To ensure the stability and reliability of PW-ECM process, a new combined machining method of PW-ECM assisted with ultrasonic vibration （PW-ECM/USV） is devised. Trilateral and square cavities and holes as well as a group of English alphabets are worked out on a stainless steel plate. It is confirmed that PW-ECM will be probably an efficient new aviation precision machining method.     

退火工艺对磁控溅射LiCoO2薄膜形貌与力学性能的影响

采用磁控溅射方法在单晶Si(100)上制备LiCoO_2薄膜并选择不同退火温度、保温时间和退火气氛对薄膜进行热处理,研究不同退火条件对LiCoO_2薄膜形貌、组成、晶体结构和力学性能的影响。结果表明:退火过程将LiCoO_2薄膜表面粗糙度从11.63 nm降低至6.13 nm,且退火气氛对LiCoO_2薄膜表面形貌影响最大;LiCoO_2薄膜退火产生Li_2O、CoO、Co_3O_4等副产物,薄膜组成被破坏;任一退火条件均能使LiCoO_2薄膜结晶,平均晶粒尺寸约为30 nm,退火温度对LiCoO_2薄膜晶粒尺寸和残余应力影响最大;LiCoO_2薄膜退火后,其硬度H、杨氏模量Er增大一个数量级,最优退火工艺下(600℃,60 min,纯O_2气氛),H~3/E_r~2比例为0.03 GPa,抵抗塑性变形能力好。     

耐高温有机无机杂化聚酰亚胺树脂及其复合材料

文摘综述了近年来国内外在有机无机杂化聚酰亚胺树脂及其复合材料方面的研究进展,重点介绍了含笼状倍半硅氧烷和硅氧烷结构的有机无机杂化聚酰亚胺树脂的制备方法,对树脂的分子结构与其耐热性和热氧化稳定性之间的关系进行了分析总结,并对有机无机杂化聚酰亚胺树脂及其复合材料的应用和未来发展进行了探讨。     

高长径比银纳米线的制备及其透明导电薄膜性能

为改善产品长径比,本文在经典多元醇法的基础上,经过常压滴注路线和密闭溶剂热路线分别制备银纳米线。详细讨论了反应时间、反应气氛及反应物投料比等相关参数对银纳米线的产率和长径比的影响。发现密闭溶剂热法在缓解环境污染的同时降低了生长过程中的扰动,所得银纳米线平均直径约55 nm,长度约65μm,长径比接近1 200。以之制备的透明导电薄膜的方阻仅6Ω,波长550 nm下透光度为78. 6%,品质因数(FOM)高达246,优于常压滴注路线。