文武双全的“天基红外系统”——美国新一代导弹预警卫星

据美国全球安全网2010年12月13日报道,美国已成功完成首颗＂天基红外系统＂地球静止轨道卫星的最终集成系统测试,该卫星将于2011年春天用宇宙神-5火箭从卡纳维拉尔角空军基地发射,它将显著提升美国的导弹预警能力和对其他重要国家安全任务的同步支持能力,包括导弹防御、技术情报和战场太空感知。     

2010年各国航天发射活动回顾(上)

2010年全球共进行74次航天发射,其中美国15次(卡角8次,肯尼迪3次,范登堡3次,科迪亚克1次),俄罗斯31次(拜科努尔24次,普列谢茨克6次,亚斯内1次),欧洲(库鲁)6次,中国15次(西昌8次,酒泉4次,太原3次).日本(种子岛)2次,印度(斯里哈里科塔)3次,韩国(罗老宇宙中心)1次,以色列(帕勒马希姆)1次.     

众眼看宇宙

火红的云气如烈焰般肆虐飞舞,这就是御夫座AE星（红色区域的中心）呈现给我们的奇观,它也因此而得名“火焰星”,周围的星云（编号为IC 405）则称为火焰星云。事实上,这些奔涌着的红色的烟尘,与我们熟知的烈火没有半点关系。一般的火焰是物质在氧气助燃时形成的光热现象,在恒星周围氧原子稀缺的区域,当然无法产生火焰。照片中的红色云气其实大部份是散布在星际空间中的氢原子,     

众眼看宇宙

纠结的旋臂加上怪异的星系之“眼”,让这个名为NGC1097的旋涡星系呈现出魔幻般的妖异气息。其实那只“眼睛”的蓝白色“瞳仁”是一个正在吸积物质而发出炽热辐射的超级黑洞,外围的白色光晕则是无数聚集成环的恒星,受到向星系棒上掉落的气体的引力扰动,其中正在诞生大量新恒星。     

60亿千米云和月“隼鸟”远行7年后回家

6月13日,日本宇宙探索局的“隼鸟”号小行星探测器再入大气层,降落在澳大利亚南部伍麦拉附近的沙漠地带,时隔7年后回归地球。期间,多灾多难,百折不挠,“隼鸟”由此也博得“不死鸟”的尊称。     

俄罗斯计划发射2个太空实验室

据中国国防科技信息网2012年9月3日消息,俄罗斯正在规划未来4年内发射2个太空实验室。其中一个太空实验室波普-RG(Spektr-RG),用于观察X射线和研究宇宙超大质量黑洞构造,将在2013年发射,质量2 385kg,可携带有效载荷1 100kg,在轨寿命预计7.5年。     

众眼看宇宙

黑洞是爱因斯坦广义相对论预言的一种天体。这幅图片是一位艺术家所作,为我们展示了一个快速旋转的黑洞,它周围的吸积盘以及中心产生的喷流。从物理常识中,我们知道一个物体的运动速度过快,便会由于离心运动而四分五裂,但是黑洞却不会。     

复合材料层合板结构冲击损伤数值模拟的损伤力学模型

针对复合材料结构低速冲击损伤问题,基于连续损伤力学提出了一种动力学冲击条件下的三维损伤数值模型。模型中区分了层内损伤（纤维拉伸与压缩失效、纤维间拉伸与压缩失效）和层间分层损伤不同的失效模式。采用三维Puck失效准则与考虑压缩抑制效应的Aymerich准则对上述两类损伤进行判定,材料失效后基于连续损伤力学中线性软化模型对材料损伤进行演化。模型中考虑了复合材料层合板结构中子层的就位效应和损伤分析中的“连锁效应”。通过对Shi的冲击试验进行数值模拟,模型预测的冲击接触载荷、分层形状和尺寸与试验结果吻合较好,证明了所提出的数值模型对复合材料层合板结构低速冲击损伤预测的有效性。     

An Overview of Performance Characteristics, Experiences and Trends of Aerospace Engine Bearings Technologies

In this paper, the operating conditions, technical requirements, performance characteristics, design ideas, application experiences and development trends of aerospace engine bearings, including material technology, integration design and reliability, are reviewed. The development history of aerospace engine bearing is recalled briefly at first. Then today＇s material technologies and the high bearing performances of the bearings obtained through the new materials are introduced, which play important roils in the aeroengine bearing developments. The integration design ideas and practices are explained to indicate its significant advantages and importance to the aerospace engine bearings. And the reliability of the shaft-bearing system is pointed out and treated as the key requirement with goals for both engine and bearing. Finally, as it is believed that the correct design comes from practice, the pre-qualification rig testing conducted by FAG Aerospace GmbH ＆ Co. KG is briefly illustrated as an example. All these lead to the development trends of aerospace engine bearings from different aspects.     

Experimental Investigation of a Fixed-geometry Two-dimensional Mixed-compression Supersonic Inlet with Sweep-forward High- light and Bleed Slot in an Inverted ＂X＂-type Layout

A fixed-geometry two-dimensional mixed-compression supersonic inlet with sweep-forward high-light and bleed slot in an inverted ＂X＂-form layout was tested in a wind tunnel. Results indicate： （1） with increases of the free stream Mach number, the total pressure recovery decreases, while the mass flow ratio increases to the maximum at the design point and then decreases; （2） when the angle of attack, a, is less than 6°, the total pressure recovery of both side inlets tends to decrease, but, on the lee side inlet, its values are higher than those on the windward side inlet, and the mass flow ratio on lee side inlet increases first and then falls, while on the windward side it keeps declining slowly with the sum of mass flow on both sides remaining almost constant; （3） with the attack angle, a, rising from 6° to 9°, both total pressure recovery and mass flow ratio on the lee side inlet fall quickly, but on the windward side inlet can be observed decreases in the total pressure recovery and increases in the mass flow ratio; （4） by comparing the velocity and back pressure characterristics of the inlet with a bleed slot to those of the inlet without, it stands to reason that the existence of a bleed slot has not only widened the steady working range of inlet, but also made an enormous improvement in its performance at high Mach numbers. Besides, this paper also presents an example to show how this type of inlet is designed.