高温处理对中密度针刺C/C复合材料性能的影响

针对C/C复合材料脆性问题,对密度为1.60 g/cm3的碳布叠层针刺C/C复合材料进行了1800、2 000、2 200和2 500℃的高温处理,研究了不同热处理温度对C/C复合材料微晶结构、力学和抗热震等性能的影响.结果表明,高温处理使针刺C/C复合材料的层间剪切和面内拉伸强度出现不同程度的降低,但材料的断裂伸长率和抗热震性能得到大幅度提高.其中,1 800℃高温处理后的C/C复合材料具有优异的力学和抗热震性能.     

复合材料用国产中温固化结构胶膜性能研究

研制了一种新型国产中温固化结构胶膜ACTECH^?1206F,通过DSC、流变、挥发分和单位面积重量等测试表征其理化性能,通过单搭接剪切强度、滚筒剥离强度、平面拉伸强度等测试表征其对不同基材的粘接性能,并与目前常用的进口胶膜FM-73进行对比试验。结果显示,与FM-73相比,ACTECH^?1206F胶膜在室温下Al-Al单搭接剪切强度、室温下碳纤复合材料单搭接剪切强度、室温下蜂窝夹层结构平面拉伸强度等方面表现较好,室温下Al-Al单搭接剪切强度可达37.7 MPa,室温下碳纤复合材料(BA3202W)单搭接剪切强度可达28.8 MPa,室温下蜂窝夹层结构平面拉伸强度可达10.32 MPa。同时,通过SEM观察了ACTECH^?1206F胶膜树脂浇铸体的断口形貌,断口较为粗糙,具有明显的曲折裂痕,是典型的韧性断裂,表明ACTECH^?1206F胶膜树脂具有良好的韧性。整体来看,ACTECH^?1206F胶膜整体性能与FM-73大致相同,可以基本满足民机复合材料领域对中温固化结构胶膜的需求...     

陶瓷前驱体基高温高辐射涂层制备及表征

以陶瓷前驱体树脂为成膜物,以过渡金属氧化物和硼化物为填料,采用空气喷涂工艺在镍基高温合金和C/C基材上制备出了高温散热性能好、抗热震性好的高温高辐射涂层,并用DSC-TG、光学显微镜和风洞对涂层性能进行表征。结果表明:该涂层室温~827℃发射率达到0.85~0.92,827℃~室温抗热震循环20次后涂层不剥离、不脱落;该涂层在290 k W/m2冷壁热流、300 s时长的风洞考核条件下,可将镍基高温合金基材温度从686℃降到646℃,降温40℃。     

热压辅助先驱体裂解制备的三维Cf／Si—O—C复合材料的微观结构与力学性能

采用聚硅氧烷(PSO)先驱体浸渍裂解工艺制备出碳纤维三维编织物增强Si—O—C复合材料(3D-B C_(?)/Si—O—C)。研究发现,第一周期采用热压辅助裂解可以显著提高材料的力学性能与致密度。第一周期经1600℃、10MPa的条件热压裂解处理5min后,材料的弯曲强度和断裂韧性从未处理前的246.2MPa和9.4MPa·m~(1/2)提高到502MPa和23.7MPa·m~(1/2)。该材料的弯曲强度在真空中可以保持到1400℃。探讨了工艺参数对材料结构与力学性能的影响。高温裂解弱化界面结合同时提高纤维就位强度以及加压提高材料致密度是热压辅助裂解能提高材料力学性能的主要原因。     

蜂窝夹层结构粘接用聚酰亚胺胶膜的研究

采用热固性聚酰亚胺胶黏剂KHPIA-S制备了聚酰亚胺胶膜,系统研究了胶膜的厚度以及表面处理剂对复合材料蜂窝夹层结构粘揍性能的影响规律.结果表明,制备的聚酰亚胺胶膜具有优异的高温粘接性能,在320℃下对不锈钢试片粘接的剪切强度超过11 MPa,对蜂窝夹层结构粘接的平拉强度最高可达2.1 MPa.     

陶瓷防热瓦用应变隔离垫的制备及性能

通过SEM等手段对以芳纶纤维为原料,采用针刺工艺制备的应变隔离垫的微观结构、力学、粘接和耐温性能进行表征与分析。结果表明：当针刺密度为35 针/cm²、材料密度为0.18 g/cm³时,材料具有很好的应变协调能力和力学性能,经200℃以下温度热处理,材料无明显变化,强度仍可达0.9 MPa。在风洞考核环境下,陶瓷瓦热防护组件最高表面温度1 500℃,风洞考核后,组件无开裂、松动现象,验证了应变隔离垫用于陶瓷瓦粘接的可靠性。     

Mo-Si涂层C/SiC复合材料的氧化性能

采用刷涂法在C/SiC复合材料表面制备Mo-Si抗氧化涂层,研究涂层的微观结构、氧化性能和热震性能.结果表明,涂层中存在微裂纹等缺陷,物相组成为MoSi2、SiO2、SiC和Si.1 400℃氧化时,微裂纹等缺陷迅速愈合.单层Mo-Si涂层试样经5 h氧化后,失重率高速5.90%,贯穿裂纹是涂层失效的主要原因.三层Mo-Si涂层试样经140h氧化后,失重率仅为1.37%,失重速率为3.80×10-5g/(cm2·h).在1 400℃(←→)100℃的热震过程中,涂层保持完整,热震50次的失重率为0.34%.经25次和50次热震后,涂层试样的弯曲强度保持率分别为90.30%和74.56%.三层涂层具有优异的抗氧化和抗热震性能,这与涂层的制备工艺和结构密切相关.     

国产芳纶纤维复合材料用环氧树脂体系

研制了一种环氧/ 芳香胺体系,采用DSC、固化反应动力学分析等方法对树脂体系进行了表征,并
对其浇注体、复合材料NOL 环以及Φ150 mm 压力容器性能进行了研究。结果表明,该树脂体系具有优良的浇
注体力学及热性能,其拉伸强度为101 MPa,断裂伸长率达4. 1%,弯曲强度为177 MPa,马丁耐热温度为
142． 2℃;与国产芳纶纤维的界面粘接性能良好,其NOL 环层间剪切强度可以达到52. 1 MPa,制备的复合材料
Φ150 mm 压力容器PV / W 值可达38. 44 km。     

原位生成Si2N2O与β-Si3N4晶种协同增韧Si3N4复相陶瓷研究

采用原位生成Si2N2O与添加β-Si3N4晶种的方法协同增韧,利用凝胶注模成型、无压烧结制备了Si3N4复相陶瓷材料,研究了协同增韧对材料力学性能和显微结构的影响.结果表明:通过添加5%(质量分数)的SiO2原位生成Si2N2O使材料的弯曲强度和断裂韧度有明显提高,分别达到359.8 MPa和4.67 MPa·m1/2,通过添加5%质量分数的β-Si3N4晶种,得到的Si3N4复相陶瓷材料中柱状β-Si3N4相生长完好、均匀分布,与板状Si2N2O结合良好.综合以上两种增韧机制使材料的力学性能进一步提高,弯曲强度为486.7 MPa,断裂韧度达到6.38 MPa·m1/2.     

Ti/Ni/Ti复合层TLP扩散连接Si3N4陶瓷与接头质量控制

研究了Ti/Ni/Ti复合层TLP扩散连接Si3 N4 陶瓷。结果表明 ,Ni Ti过渡液相存在时间短 ,在此期间形成的界面结合强度低 ;必须进一步固态扩散反应才能形成高强度接头 ,相应的接头显微结构为 :Si3 N4 /TiN/Ti5Si3+Ti5Si4 +Ni3 Si/NiTi/Ni3 Ti/Ni。连接时间、连接温度、连接压力及Ti和Ni的厚度影响接头组织和强度 ,其最佳值为 6 0min ,10 5 0℃、2 .5MPa、2 0 μm和 40 0 μm ,所得接头室温和 80 0℃剪切强度分别为 142MPa和 6 1MPa。     

有翼高超声速再入飞行器气动设计难点问题

有翼高超声速再入飞行器是近年来的研究热点,气动设计是飞行器设计的关键。为了更清楚地认识有翼高超声速再入飞行器气动设计的难点问题,对有翼高超声速再入飞行器的发展、优势及总体任务剖面进行了介绍,从5个方面详细介绍了该类飞行器气动设计的难点问题,包括多约束复杂面对称气动布局设计、高温真实气体效应对气动特性影响、天地差异与天地换算方法、反作用控制系统(RCS)喷流干扰对气动特性的影响以及气动数据不确定度等,简要阐明了这些难点问题对总体设计的重要性以及初步的解决思路,为有翼高超声速再入飞行器气动设计提供了一些参考。     

Simulation and Analysis of Crashworthiness of Fuel Tank for Helicopters

Crashworthiness requirement of fuel tanks is one of the important requirements in helicopter designs. The relations among the protection frame, textile layer and rubber layer of the fuel tank are introduced. Two appropriate FE models are established, one is for an uncovered helicopter fuel tank without protection frame, and the other is for fuel tank with protection frame. The dynamic responses of the two types of fuel tanks impinging on the ground with velocities of 17.3 m/s are numerically simulated for the purpose of analyzing energy-absorbing capabilities of the textile layer and protection frame. The feasibility of the current crashworthiness design of the fuel tank is examined though comparing the dynamic response behaviors of the two fuel tanks.     

The effect of inlet conditions on the flow and heat transfer in multiple rotating cavity with axial throughflow

This paper discusses experimental results from two different build configurations of a heated multiple rotating cavity test rig.Measurements of heat transfer from the discs and tangential velocities are presented.The test rig is a 70% full scale version of a high pressure compressor stack of an axial gas turbine engine.Of particular interest are the internal cylindrical cavities formed by adjacent discs and the interaction of these with a central axial throughflow of cooling air.Tests were carried out for a range of non-dimensional parameters representative of high pressure compressor internal air system flows(Re up to 5×106 and Rez up to 2×105).Two different builds have been tested.The most significant difference between these two build configurations is the size of the annular gap between the(non-rotating) drive shaft and the bores of the discs.The heat transfer data were obtained from thermocouple measurements of surface temperature and a conduction solution method.The velocity measurements were made using a two component,LDA system.The heat transfer results from the discs show differences between the two builds.This is attributed to the wider annular gap allowing more of the throughflow to penetrate into the cavity.There are also significant differences between the radial distributions of tangential velocity in the two builds of the test rig.For the narrow annular gap,there is an increase of non-dimensional tangential velocity V/Ωr with radial location to solid body rotation V/Ωr=1.For the wider annular gap,the non-dimensional velocities show a decrease with radial location to solid body rotation.      

突破技术趋同，波音再现竞争优势

 波音公司面临着来自空客公司的巨大挑战,企业战略性创新才是公司成功的关键。为此波音公司的全部战略性研究集中在扩大产品的差异性上,体现在3个方面：电子化（e-Enabled）运营环境、整体复合材料机身部件的制造技术和支持波音787客机的全球协同环境（GCE）。     

ν-gap度量及其在飞行控制律评估中的应用

 传统控制律评估方法主要用于单输入单输出（SISO）系统，且对模型参数摄动考虑不够全面,针对这些不足，研究了ν-gap度量方法。在介绍系统广义稳定裕度相关概念的基础上，给出了ν-gap度量的定义、特点和性质以及近似摄动模型的计算，提出ν-gap度量评估控制律的步骤。实例结果表明，该方法不仅克服了上述传统评估方法的缺陷，而且还有根据所求的各摄动影响情况忽略影响小的元素，以减少计算量及可以找到最坏情况下的参数摄动组合等优点。     

临近空间飞行器测控与信息传输系统频段选择

 临近空间飞行器是高性能信息化武器平台,测控（TT&;C）与信息传输系统是其信息保障的核心,而选择合理、可行的频段是展开系统设计的前提和基础。频段选择影响到整个技术方案的制定,是一个需综合考虑、影响深远并具有战略意义的关键问题,从国际电联（ITU）国际标准、高速数传、接收信噪比（SNR）、“三抗”、超视距中继、黑障、雨衰以及设备研制成熟度8个方面全面、细致论证了近空间平台测控系统的频段选择问题,最终得出在视距链路中以Ka频段为宜,在超视距链路中以Ku/Ka双频段为宜的结论。     

基于弯曲激波压缩系统的高超声速进气道反设计研究进展

总结了近十年来弯曲激波压缩研究的主要成果。提出了弯曲激波压缩系统的新概念,即利用特殊设计的楔形弯曲压缩面或空间弯曲压缩面,产生一系列与前缘弱激波相互交汇或叠加的压缩波系,从而使前缘激波弯曲,形成特殊的弯曲激波,它与波后的等熵压缩波来共同完成对气流的压缩。在此基础上,实现了由给定出口气动参数的超声速内流道反设计,实现了由给定压缩面压力分布和给定压缩面马赫数分布要求的型面反设计,实现了由给定激波波面的压缩型面反设计。研究证明,弯曲压缩面-弯曲激波压缩系统具有良好的综合气动性能,为高性能高超声速进气系统的气动设计提供了一种全新的设计方法。     

Integrated Entry Guidance for Reusable Launch Vehicle

A method for the implementation of integrated three-degree-of-freedom constrained entry guidance for reusable launch vehicle is presented. Given any feasible entry conditions, terminal area energy management interface conditions, and the reference trajectory generated onboard then, the method can generate a longitudinal guidance profile rapidly, featuring linear quadratic regular method and a proportional-integral-derivative tracking law with time-varying gains, which satisfies all the entry corridor constraints and meets the requirements with high precision. Afterwards, by utilizing special features of crossrange parameter, establishing bank-reversal corridor, and determining bank-reversals according to dynamically adjusted method, the algorithm enables the lateral entry guidance system to fly a wide range of missions and provides reliable and good performance in the presence of significant aerodynamic modeling uncertainty. Fast trajectory guidance profiles and simulations with a reusable launch vehicle model for various missions and aerodynamic uncertain-ties are presented to demonstrate the capacity and reliability of this method.     

Experimental Study on Effects of Fuel Injection on Scramjet Combustor Performance

In order to investigate the effects of fuel injection distribution on the scramjet combustor performance, there are conducted three sets of test on a hydrocarbon fueled direct-connect scramjet test facility. The results of Test A, whose fuel injection is carried out with injectors located on the top-wall and the bottom-wall, show that the fuel injection with an appropriate close-front and centralized distribution would be of much help to optimize combustor performances. The results of Test B, whose fuel injection is performed at the optimal injection locations found in Test A, with a given equivalence ratio and different injection proportions for each injector, show that this injection mode is of little benefit to improve combustor performances. The results of Test C with a circumferential fuel injection distribution displaies the possibility of ameliorating combustor performance. By analyzing the effects of injection location parameters on combustor performances on the base of the data of Test C, it is clear that the injector location has strong coupled influences on combus- tor performances. In addition, an inner-force synthesis specific impulse is used to reduce the errors caused by the disturbance of fuel supply and working state of air heater while assessing combustor performances.     

(高)超声速流动试验技术及研究进展

近年来,与高速飞行器相关的(高)超声速流动受到了极大的关注。这类流动所具有的非定常性、强梯度和可压缩性对试验方法和风洞设计技术提出了挑战。超声速纳米示踪平面激光散射(NPLS)技术是由作者所在团队研发的非接触光学测试技术。它能够以较高的空间分辨率来揭示超声速三维流场的一个瞬态剖面的时间解析的流动结构。介绍了NPLS技术以及基于NPLS开发的密度场测量、雷诺应力测量和气动光学波前测量等方法,并回顾了这些技术在超声速边界层、超声速混合层、超声速压缩拐角、激波/边界层相互作用和光学头罩绕流等流动中的应用,清晰地再现了边界层、混合层、激波等典型流场结构及其时空演化特性。另外,为了模拟和研究高空大气条件下边界层自然转捩和超声速混合层的转捩特性,介绍了高超声速静风洞、超-超混合层风洞的设计技术以及层流化喷管的设计方法。