“德尔它”商用中型运载火箭

概述“德尔它”Ⅱ中型运载火箭发射商用载荷的情况.“德尔它”系列火箭的特点是可靠性很高.航天飞机的失事,使美国重新考虑起用一次性使用运载火箭.“德尔它”Ⅱ便能满足90年代卫星商业市场的需求,经过不断改进,它最终能将1450—1800kg的载荷送上地球同步轨道.详细介绍“德尔它”Ⅱ的性能与各级的结构特点,及火箭目前的研制状况.     

特殊套装的可变面积比可延伸出口锥的设计特性和现状

本文论述一种新的 EEC 方案,本方案不受其它“传统的”EEC 方案的限制,它具有某些特有的设计优点。盖板折叠 EEC(SLEEC)由烧蚀材料或者碳碳材料做成的许多块内外盖板组成。这些盖板重叠特殊,并且紧密套装在喷管固定出口锥的周围,从而使收藏体积大为缩小。作动系统由同步的轴向和径向传动装置组成,这种传动装置当反作用力引起轴向和环向载荷时同时提供延伸和径向扩展。因此锥越来越大而得到展开,使锥成为一个膨胀面确实可变的装置,在火箭发动机的加速级允许最佳高度补偿。对 SLEEC 的不同应用所获得的性能作了对比研究。     

固体推进剂空隙含量的体积模量测定

本研究采用体积压缩系数测量来确定固体推进剂中因气体逸出而导致的内部空隙含量(空隙区)的变化。而且测定了复合改性双基(CMDB)、交联双基(XLDB)和硝酸酯增塑聚醚(NEPE)三种推进剂体内空隙形成的速率。发现在400mm立方体内空隙含量和体积压缩系数,同用X—射线的检查结果具有良好的一致性。在这三种推进剂中,采用70和80℃下的高温贮存来加速空隙的形成。其中CMDB推进剂显示出最高的空隙形成速率。最后,探讨了断裂力学在空隙形成研究中应用的最新进展。     

A380发动机的最新进展

GE-普惠联盟公司和罗-罗公司都在为A380研制发动机,前者研制的是GP7000,后者研制的是遄达900。GP7000现已完成大量地面试验,预计9月末进行空中试车台首飞。遄达900的研制进度稍快些,现已完成空中试车台首飞,并将在10月取得适航合格证,明年初装在A380上进行首飞     

碳纤维复合材料电火花加工(EDM)机理究研

应用于航空航天技术的碳纤维复合材料具有相当高的比强度、高弹性模量、重量轻、热膨胀小、以及具有导电性、对酸、碱有机溶剂有很大的耐蚀性等诸多的优点。但由于材料本身为纤维织物的层压浸渍结构,使其在切削加工时难于达到较高的光洁度与精度,     

双轴载荷下孔边疲劳裂纹的扩展

 在AISI316奥氏体不锈钢制成的十字形带中心孔（圆孔和椭圆孔）试件上进行的双轴载荷疲劳裂纹扩展试验表明:应力双轴性对疲劳裂纹扩展的影响,仅发生在靠近开孔的局部区域内。等双轴应力较单轴应力状态下的裂纹扩展速率减慢,而纯剪切状态下的裂纹扩展速率加快。在孔的影响区之外,所有的结果服从Paris规律,与应力双轴性无关。     

测量GSRS导弹自旋和姿态的TMR处理技术

本报告详细叙述了用动目分辨(TMR)技术处理来自白沙靶场MPS-36,FPS-16测量雷达的数据,从而获得GSRS地-地导弹的成锥形运动和自旋运动测量值。处理了实际飞行试验数据,验证了这种技术。本文还叙述了为此编制并安装于白沙计算机的软件。     

Isothermal study of effusion cooling flows using a large eddy simulation approach

An isothermal numerical study of effusion cooling flow is conducted using a large eddy simulation(LES) approach.Two main types of cooling are considered,namely tangential film cooling and oblique patch effusion cooling.To represent tangential film cooling,a simplified model of a plane turbulent wall jet along a flat plate in quiescent surrounding fluid is considered.In contrast to a classic turbulent boundary layer flow,the plane turbulent wall jet possesses an outer free shear flow region,an inner near wall region and an interaction region,characterised by substantial levels of turbulent shear stress transport.These shear stress characteristics hold significant implications for RANS modelling,implications that also apply to more complex tangential film cooling flows with non-zero free stream velocities.The LES technique used in the current study provides a satisfactory overall prediction of the plane turbulent wall jet flow,including the initial transition region,and the characteristic separation of the zero turbulent shear stress and zero shear strain locations.Oblique effusion patch cooling is modelled using a staggered array of 12 rows of effusion holes,drilled at 30° to the flat plate surface.The effusion holes connect two channels separated by the flat plate.Specifically,these comprise of a channel representing the combustion chamber flow and a cooling air supply channel.A difference in pressure between the two channels forces air from the cooling supply side,through the effusion holes,and into the combustion chamber side.Air from successive effusion rows coalesces to form an aerodynamic film between the combustion chamber main flow and the flat plate.In practical applications,this film is used to separate the hot combustion gases from the combustion chamber liner.The numerical model is shown to be capable of accurately predicting the injection,penetration,downstream decay,and coalescence of the effusion jets.In addition,the numerical model captures entrainment of the combustion chamber mainstream flow towards the wall by the presence of the effusion jets.Two contra-rotating vortices,with axes of rotation along the stream-wise direction,are predicted as a result of this entrainment.The presence and characteristics of these vortices are in good agreement with previous published research.      

Experiment LEND of the NASA Lunar Reconnaissance Orbiter for high-resolution mapping of neutron emission of the Moon

The scientific objectives of neutron mapping of the Moon are presented as 3 investigation tasks of NASA's Lunar Reconnaissance Orbiter mission. Two tasks focus on mapping hydrogen content over the entire Moon and on testing the presence of water-ice deposits at the bottom of permanently shadowed craters at the lunar poles. The third task corresponds to the determination of neutron contribution to the total radiation dose at an altitude of 50 km above the Moon. We show that the Lunar Exploration Neutron Detector (LEND) will be capable of carrying out all 3 investigations. The design concept of LEND is presented together with results of numerical simulations of the instrument's sensitivity for hydrogen detection. The sensitivity of LEND is shown to be characterized by a hydrogen detection limit of about 100 ppm for a polar reference area with a radius of 5 km. If the presence of ice deposits in polar "cold traps" is confirmed, a unique record of many millions of years of lunar history would be obtained, by which the history of lunar impacts could be discerned from the layers of water ice and dust. Future applications of a LEND-type instrument for Mars orbital observations are also discussed.     

基于图像的测量方法在工业风洞跨声速流测量中的最新进展

风洞中非定常复杂流场的实验研究要求先进的测量技术.基于图像的测量技术中最重要的是测量平面流速度场、平面压强分布、模型位置和变形、模型温度以及定量的高速流可视化等技术.DLR(德国宇航研究院)对这些技术的应用包括从低速流到跨声速流、从增升装置到螺旋桨和旋翼、从弹射装置和水塔储水罐尾迹流旋涡到三角翼上涡破裂现象等的研究.由于跨声速风洞的特殊环境,将基于图像的测量技术用于跨声速流要求专门的技术开发和有经验的科学家.给出了DLR空气动力学和流动技术研究所将基于图像的测量技术应用于跨声速流研究的最新进展.