筒形机匣连接凸耳疲劳寿命及其影响因素

分析了筒形机匣连接凸耳疲劳寿命的主要影响因素。结果表明,５个试验件凸耳组织的再结晶程度有很大的差别,正是由于凸耳组织再结晶程度的分散性导致了其疲劳寿命的分散性。进一步的分析表明,凸耳组织再结晶程度的分散性是由于模锻时材料原始晶粒大小和形变量不同造成的。此外,凸耳孔壁表面的加工缺陷也是降低凸耳疲劳寿命的一个重要因素。     

镍基高温合金铸件的晶粒组织控制──铸造工艺参数的影响

以ＩＮ７３８ＬＣ合金为例,研究了镍基高温合金在各种铸造工艺条件下的晶粒组织。结果表明,降低合金液均匀化处理温度可以明显细化冷凝后基体的晶粒。在浇注温度、铸型预热温度以及合金液均匀化处理温度等铸造工艺参数中,后者对晶粒尺寸的影响大于前两者。     

反压条件下同轴式喷嘴雾化特性的试验研究

利用作者设计的反压试验装置和MF激光散射测粒仪, 在0.1～0.6MPa反压条件下, 测量了不同工况液雾的索太尔平均直径SMD等雾化特性参数, 并对试验数据进行最小二乘拟合, 得到了影响雾化特性相关参数的经验公式, 对同轴式喷嘴的设计将有一定的指导意义。      

Experimental of combustion instability in NTO/MMH impinging combustion chambers

This paper presents an experimental study into dynamics of chamber pressure and heat release rate during self-excited spinning and standing azimuthal mode in NTO/MMH (nitrogen tetroxide/monomethylhydrazine) impinging combustion chambers. Nine cases including two combustion chamber configurations were conducted. The operating conditions of all unstable cases were located in the instability region according to Hewitt empirical correlation. The results show that chamber pressure oscillations keep pace with the corresponding OH* chemiluminescence intensity over the whole combustion region in the spinning and standing modes. It is indicated that the Rayleigh index is positive over the whole combustion area in all the unstable cases. A significant supersonic flame front structure of the first-order spinning mode was found in a cylindrical chamber, which means that a detonation wave could exist in the cylindrical chamber without a center body. The pressure and heat release rate oscillations at the pressure node are nonnegligible although their amplitudes are lower than those at the pressure antinode in the first-order standing mode with an annular chamber. Besides, the dominant frequency of pressure and heat release rate oscillations at the pressure node is twice as high as that at the pressure antinode.     

Wear Behaviour of Electroless Ni-P-Diamond Composite Coatings

The wear behaviour of composite coatings is related to the nature of embedded particles.The effects of particle size on the wear behaviour of composite coatings are analyzed.Electroless nickel composite coatings containing diamond particles with the sizes in the range of 0—0.5,0.5—1,1—2μm are prepared.The surface morphology of diamond particles and composite coatings are observed by scanning electron microscopy(SEM).The wear tests of composite coatings are comparatively evaluated by sliding against a cemented tungsten carbide ball.The 3D morphology of worn scar is evaluated by using a 3Dprofiler.The results show that the hardness and wear resistance of composite coatings can increase with the increase of particle sizes.The mixture mechanism of adhesive wear and abrasive wear turn into single abrasive wear with the increase of particle sizes as well.The transformation of wear behaviour is mainly attributed to particle roles during wear process.     

航空用6061铝合金板材性能验证试验研究

介绍了6061铝合金板材性能特点及其在飞机上应用情况,结合飞机使用要求,分析国产6061板材在飞机上应用存在问题,并对板材焊接、成形及耐压进行考核验证试验。结果表明,国产6061铝合金板材焊接接头连接效率可达90%以上,与传统防锈铝相当,拉伸强度高于进口板材;利用拉深工艺制备大规格薄壁管型件是可行的,研制出的工件尺寸完全符合图纸要求;耐压性能满足使用要求,但国产材料的耐压稳定性略低于进口材料。     

Post-Newtonian tracking formulae to increase the shooting accuracy of autonomous LEO laser trackers

We introduce five post-Newtonian tracking formulae that would allow increasing the accuracy of the shooting systems on board autonomous LEO laser trackers. These formulae should be used when the current formulae cannot provide instants close enough to the optimal instants at which the trackers could safely shoot down unwished LEO middle-distant targets. In fact, they allow the trackers to produce not only the safest shooting actions, but also the most efficient ablations that might make the targets fall into the atmosphere for them to burn. The fact of the matter is in the falsifiability procedure introduced below, which allows to simulate sequences of unharming shooting actions with very narrow laser beams leading to identify the optimal pointing directions to previously selected debris objects whose size and composition are representative of these targets.     

移动粒子半隐式方法GPU加速的双股射流撞击雾化模拟

为实现双股射流撞击雾化过程的高效数值求解并探究射流速度和撞击角度对雾化特性的影响规律，实现了移动粒子半隐式方法（MPS）GPU加速的双股射流撞击雾化模拟。GPU加速程序的最大加速比为16，取得了较好的加速效果。将GPU加速MPS方法应用于典型工况下的双股射流撞击雾化模拟，成功捕捉到了多尺度的液膜形成、液膜破碎成液丝继而破碎成液滴的瞬态过程，模拟得到的液膜破碎长度及雾化角度与试验较为吻合，误差分别为11.7%和0.5%，验证了GPU加速MPS方法在双股射流撞击雾化问题中处理能力。参数化分析了射流速度和撞击角度对液膜破碎长度、雾化角度及一次雾化液滴索尔直径的影响。结果表明撞击角度增加或者射流速度增加均会导致液膜破碎长度减小、雾化角度增加、一次雾化液滴索尔直径减小。     

晶粒尺寸对钛合金TIG焊接接头组织及力学性能的影响

进行了2μm及8μm,19μm三种晶粒尺寸的细晶粒TC4钛合金常规TIG焊试验,分析了母材晶粒尺寸对钛合金焊接接头组织转变规律及力学性能的影响。结果表明,细晶粒TC4钛合金焊缝中心和热影响区组织相似,为α马氏体组织。相同焊接规范下,随着晶粒尺寸的减小,焊缝中心和热影响区组织由编织(网篮)状α组织向片状组织过渡;随着晶粒尺寸的减小,热影响区晶粒长大越来越明显,热影响区细晶区(FHAZ)明显变窄,热影响区粗晶区(CHAZ)明显变宽,焊缝—热影响区—母材的晶粒梯度增大,焊接接头三区域晶粒过渡越来越差;随着晶粒尺寸的减小,焊接接头拉伸强度和伸长率均有不同程度的提高。常温拉伸断口呈准解理断裂特征,随着母材晶粒度的增大,焊接接头解理断裂特征越明显。     

裂纹萌生寿命预腐蚀影响规律

对不同预腐蚀时间的裂纹萌生寿命进行统计分析,并选取了4种函数形式对（CT）数据进行拟合对比分析。结果表明,指定裂纹尺寸的裂纹萌生寿命随腐蚀时间的增加而降低,在工程常用的时间范嗣内,若假定裂纹萌生寿命服从对数正态分布,指定裂纹尺寸的对数裂纹萌生寿命标准差与预腐蚀时间基本无关,单参数指数函数形式拟合的不同裂纹尺寸的C-T曲...