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Extensive experimental studies on the heat transfer characteristics of two rows of aligned jet holes impinging on a concave surface in a wing leading edge were conducted, where50000 Rej 90000, 1.74 H/d 27.5, 66° a 90°, and 13.2 r/d 42.03. The finding was that the heat transfer performance at the jet-impingement stagnation point with two rows of aligned jet holes was the same as that with a single row of jet holes or the middle row of three-row configurations when the circumferential angle of the two jet holes was larger than 30°. The attenuation coefficient distribution of the jet impingement heat transfer in the chordwise direction was so complicated that two zones were divided for a better analysis. It indicated that: the attenuation coefficient curve in the jet impingement zone exhibited an approximate upside-down bell shape with double peaks and a single valley; the attenuation coefficient curve in the non-jet impingement zone was like a half-bell shape, which was similar to that with three rows of aligned jet holes; the factors,including Rej, H/d and r/d, affected the attenuation coefficient value at the valley significantly.When r/d was increased from 30.75 to 42.03, the attenuation rates of attenuation coefficient increased only by 1.8%. Consequently, experimental data-based correlation equations of the Nusselt number for the heat transfer at the jet-impingement stagnation point and the distributionof the attenuation coefficient in the chordwise direction were acquired, which play an important role in designing the wing leading edge anti-icing system with two rows of aligned jet holes. 相似文献
84.
Chen Long 《中国航天(英文版)》2013,(1):2-4
2012 was an impressive year for China’s space industry. Multiple national space programs proceeded well and as one of world’s well known rockets, the LM launch vehicles conducted 19 missions and sent 28 satellites/ spaceship into their preset orbits in 2012. All these spacecraft had been delivered to the customers for operation. CASC vice president Yuan Jie introduced the CASC space missions of 2012 when interviewed by Aerospace China. 相似文献
85.
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. 相似文献
86.
CHEN Long 《中国航天(英文版)》2015,(1):19-20
<正>Chang’e 5-T1,the Earth re-entry demonstrator in phase III of the Chinese Lunar Exploration Program was sent on an Earth-Moon free return trajectory onboard a LM-3C launch vehicle at 2:00 am Beijing Time on October 24,2014.Chang’e 5-T1 also carried a private mission to the moon as a piggyback payload called the 4M mission(Manfred 相似文献
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运动油滴/固体壁面斜碰撞的状态辨识及特征分析 总被引:2,自引:1,他引:1
航空发动机轴承腔油气两相流动与换热研究是轴承腔润滑与换热设计的重要基础工作,而运动油滴与轴承腔壁面的碰撞状态辨识及特征分析是轴承腔油气两相流动与换热研究的组成部分。基于VOF方法建立了运动油滴与固体壁面斜碰撞数值仿真模型,实现了运动油滴与固体壁面斜碰撞状态的数值模拟,分析了碰撞油滴直径、入射角和碰撞速度对沉积油膜铺展长度、油膜堆积厚度和溅射油滴数目等碰撞状态特征参数的影响规律,提出了运动油滴与固体壁面斜碰撞条件下的状态判断准则,并得到了文献的物理试验工作的支持。研究结果表明:随着油滴入射角减小,沉积油膜铺展长度和油膜堆积厚度增大,溅射油滴数目减少;随着碰撞速度和油滴直径的增大,沉积油膜铺展长度和溅射油滴数目均增大,但油膜堆积厚度对应前者呈减小趋势、对应后者仍呈增大趋势。 相似文献
89.
C. J. Gramling A. C. Long 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1995,16(12):77-80
The National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) is currently developing a Tracking and Data Relay Satellite (TDRS) System (TDRSS) Onboard Navigation System (TONS) to provide onboard knowledge of highly accurate navigation products autonomously to users of TDRSS. The TONS I operational system processes Doppler data derived from scheduled forward-link S-band services to provide onboard orbit and frequency determination and time maintenance. TONS I is implemented using a stable onboard frequency reference, a Doppler measurement capability in the user transponder, and onboard navigation/signal acquisition software. The success of the TONS experiment (1992/1993), which was implemented on the Explorer Platform/Extreme Ultraviolet Explorer (EP/EUVE) spacecraft, demonstrated the flight readiness of TONS I. TONS II-A provides the user with additional Doppler data derived from an S-band beacon signal, available approximately 80 percent of the time. This paper describes the TONS operational capabilities, configurations, and expected performance. 相似文献
90.
Knox S. Long 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1982,2(9):177-188
An extensive program to study nearby normal galaxies was carried out by various observers using the imaging instruments on the Observatory; more than 50 such galaxies were detected with 0.5 – 3.0 keV luminosities ranging from 2 × 1038 ergs s?1 to 3 × 1041ergs s?1. The X-ray luminosity of normal galaxies is ~2 × 10?4 of the optical luminosity and shows no strong correlation with morphological type. For the nearest galaxies, (the Large and Small Magellanic Clouds, M31 and M33,) studies, performed with the Observatory, were comparable to the survey of the Galaxy. Approximately 30 new SNR were recognized in the Magellanic Clouds as a result. Over 90 sources were detected in M31 of which at least 20 are identified with globular cluster. The numbers of luminous (>1037 ergs s?1) sources detected in the nearest galaxies per unit mass are similar to that found in our own galaxy. Individual X-ray sources in the arms of nearby spirals can be very luminous; seven with luminosities in excess of 1039ergs s?1 have been discovered. The nuclei of some, but not all, normal galaxies are luminous X-ray sources; X-ray activity is not presently predictable from the radio or optical properties of the nucleus. 相似文献