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241.
本文总结了测量轴流压气机失速喘振工况及端壁边界层流场时所采用的方法,并提供若干典型结果。大量试验表明这些方法行之有效。用三支同型探针,沿周向不等间隔分布,失速喘振时,用频谱分析确定频率成分,用互相关分析确定两两信号的时差,即可判明是失速或喘振,并决定团数、团的传播速度及团的形状。用单丝旋转法测量端壁边界层以保证所测参数严格属于同一半径,同时又具有 X 型探针的二维能力,以测定速度矢量,湍流度及雷诺应力,在此测量中我们研究了机匣探针孔对边界层流场的干扰问题。灰尘油污的污染,气流温度随压气机工况的变化是遇到的主要问题。 相似文献
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A. N. Parmar G. Hasinger M. Arnaud X. Barcons D. Barret H. Bhringer A. Blanchard M. Cappi A. Comastri T. Courvoisier A. C. Fabian F. Fiore I. Georgantopoulos P. Grandi R. Griffiths A. Hornstrup N. Kawai K. Koyama K. Makishima G. Malaguti K. O. Mason C. Motch M. Mendez T. Ohashi F. Paerels L. Piro T. Ponman J. Schmitt S. Sciortino G. Trinchieri M. van der Klis M. Ward 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2004,34(12):2623
Europe is one of the major partners building the International Space Station (ISS) and European industry, together with ESA, is responsible for many station components including the Columbus Orbital Facility, the Automated Transport Vehicle, two connecting modules and the European Robotic Arm. Together with this impressive list of contributions there is a strong desire within the ESA Member States to benefit from this investment by utilizing the unique capabilities of the ISS to perform world-class science. XEUS is one of the astronomical applications being studied by ESA to utilize the capabilities of the ISS. XEUS will be a long-term X-ray observatory with an initial mirror area of 6 m2 at 1 keV that will be expanded to 30 m2 following a visit to the ISS. The 1 keV spatial resolution is expected to be 2–5″ half-energy-width. XEUS will consist of separate detector and mirror spacecraft (MSC) aligned by active control to provide a focal length of 50 m. A new detector spacecraft, complete with the next generation of instruments, will also be added after visiting the ISS. The limiting 0.1–2.5 keV sensitivity will then be 4 × 10−18 erg cm−2 s−1, around 200 times better than XMM-Newton, allowing XEUS to study the properties of the hot baryons and dark matter at high redshift. 相似文献
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李同起%王俊山%胡子君%王成扬 《宇航材料工艺》2006,36(2):1-6,55
在系统地分析了当今炭素材料研究的基础上,结合科学技术发展的方向提出了炭素科学的研究热点,认为多孔碳材料、纳米碳材料和碳基复合材料是当今炭素材料的研究热点,而由能源的开发与利用、环境的保护与治理和生命科学的发展所引出的新型应用领域则代表了未来几年乃至几十年的研究热点和发展趋势,这些炭素材料的应用则构成了当今炭素材料应用科学的主要研究内容。炭素材料的基础研究主要围绕着炭素材料的性能和应用展开。 相似文献
246.
采用热等静压预合金粉工艺对Ti-6Al-4V钛合金粉末冶金技术进行了研究,同时就原料粉状态对粉末钛合金性能的影响进行了初步研究,并进行了近净形成型工艺试验。结果表明,采用预合金粉工艺制备的Ti-6Al-4V粉末钛合金材料性能良好,且可实现近净形成型;这说明预合金粉工艺在制备高性能、低成本钛合金部件方面有良好的应用前景。 相似文献
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Microstructure and Property Analysis of AerMet100 Steel Manufactured by In-situ Rolling Mixed Wire Arc Additive Manufacturing 下载免费PDF全文
AerMet100 steel thick wall is fabricated by in-situ rolling composite wire arc additive manufacturing (WAAM). The microstructure and mechanical properties of AerMet100 steel after heat treatment are studied. The results show that after the introduction of in-situ rolling force, the grain of AerMet100 steel is broken, the anisotropy is eliminated, and the microstructure is refined obviously. The microstructure of AerMet100 steel after heat treatment is mainly lath martensite and reverse austenite. There are 40 nm?68.6 nm alloy carbides precipitated in the martensitic matrix, and the hardening mechanism is mainly Orowan bypass strengthening. The film-like reverse austenite with the thickness ranging from 2 nm to 5 nm exists between the martensitic lath, which improves the toughness of the maraging steel. Good combination of strength and toughness can be achieved through proper heat treatment process. 相似文献
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《中国航空学报》2021,34(8):192-201
Ti/Al/Mg laminated composites were successfully fabricated by hot roll bonding. The effects of the rolling reduction on the microstructural evolution and mechanical properties of the composites were explored. The results show that Ti/Al/Mg laminated sheets exhibit good interfacial bonding. The rolling reduction has a significant effect on the deformation inhomogeneity through the thickness of the Al layer. The initial grains of the Al layer near the Ti/Al interface are fragmented into fine equiaxed grains, and the grains at the center and near the Al/Mg interface are elongated. The R-cube shear texture of the Al layer forms near the Ti/Al interface and permeates into the center layer in the samples with greater rolling reductions. The β-fiber rolling texture of the Al layer is observed near the Al/Mg interface and increases with the increase of rolling reduction. The stress–strain curves indicate that the fracture appears first in the Mg layer. With the increasing rolling reduction, the ultimate tensile and yield strength values increase, and the elongation up to the Mg layer fracture decreases. 相似文献
250.
等离子体激励器控制平板边界层转捩实验研究 总被引:3,自引:1,他引:2
在低速射流风洞中,研究了单级介质阻挡放电等离子体激励器对光滑平板边界层转捩位置的控制作用。实验采用热线测量技术,以边界层速度脉动与平均速度型作为转捩判据。实验发现,在来流速度为15 m/s,激励器连续放电参数为输出电压峰峰值11 kV,频率4.7 kHz时,在激励器放电作用下,平板边界层转捩位置推迟约40 mm。在相同的来流条件和激励器布局下,研究了不同放电参数对边界层内速度型,速度脉动以及频谱分布的影响,发现提高放电电压、频率和占空比能进一步推迟转捩。实验结果表明:激励器产生的射流效应可以增强边界层流动的稳定性,随放电电压、频率以及占空比增强,射流能量增大,因此边界层稳定性进一步加强,转捩控制效果也更明显。 相似文献