1种低红外发射率涂层耐热性能研究

为有效降低飞行器高温部位表面的红外发射率,以改性有机硅为黏结剂体系、金属铝粉为主要填料,制备了在8~14μm波段具有较低红外发射率的涂层。在50~400℃温度范围内考察了涂层的耐热性能,并采用扫描电镜、TGA等手段对其进行表征,研究了涂层的红外发射率、光泽度和力学性能随温度的变化规律及影响机理。结果表明:制备的涂层在300℃以下具有良好的力学性能,可长期使用,在8~14μm波段的红外发射率与温度成反比,光泽度与温度成正比;当环境温度高于300℃,涂层开始发生热降解现象,光泽度降低,涂层的力学性能降低。     

低发射率薄膜的红外隐身特性研究

利用磁控溅射法制备了氧化铟锡（ITO）、掺铝氧化锌（ZAO）、TiO2/Ag/TiO2纳米多层等三种透明的低发射率薄膜。研究了这些低发射率薄膜以及降低材料红外发射率对降低红外辐射强度和红外隐身所起的作用。结果表明：降低红外发射率可以有效地抑制由于温度升高所带来的附加红外辐射;低红外发射率薄膜在红外隐身中有潜在应用价值。     

改性三元乙丙橡胶用于红外隐身涂层的研究

采用正交试验制备了三元乙丙橡胶接枝马来酸酐(EPDM-g-MAH),并以此为黏合剂,铜粉为填料制备了发射率可调的热红外隐身涂层,对涂层进行了红外光谱、红外发射率、微观形貌、力学性能等方面的分析.结果表明该涂层发射率可低至0.15左右,且可以显著减少填料的用量,明显提高涂层的力学性能:附着力可以从3级提高到1级,铅笔硬度从2B提高到3H,柔韧性都为1 mm,耐冲击力都大于50 cm.根据正交试验得到了优化试验条件,获得了涂层力学性能较好、红外发射率低的黏合剂材料.     

红外隐身涂层及对雷达吸波性能的影响

研究了红外雷达兼容隐身涂层红外发射率及雷达波隐身兼容性的影响因素,包括填料的类型、质量分数及涂层厚度。研究表明,以填充30wt%的HW-3型铝粉为填料,制备的涂层厚度为20μm时,涂层红外发射率达到0.25,能大幅降低材料表明红外辐射温度,且对微波隐身兼容性良好。     

大气及地面红外辐射对高空飞机长波低发射率红外隐身效果的影响

计算分析了蒙皮反射的大气及地面红外辐射对高空飞机采用低发射率材料的红外隐身效果的影响.蒙皮温度采用恢复温度,红外辐射采用反向蒙特卡罗法计算.考虑了夏季和冬季两种典型大气和地面条件,亚声速巡航和超声速巡航两种飞行状态.结果表明:蒙皮对背景红外辐射的反射使得低发射率材料对飞机红外辐射强度的抑制效率降低1.5%~6%;考虑反射的背景红外辐射时,探测距离增加20%~70%;背景红外辐射对低速飞机的红外辐射影响较大,且夏季比冬季更明显;当飞行速度较低时,降低飞机上表面发射率,当飞行速度较高时,降低飞机全部表面的发射率,可获得更好的红外隐身效果.      

空间航天器低吸收-低发射率热控涂层的设计与制备

针对密封舱类航天器在载人登月、天地往返以及绕月飞行的极端工况下保持舱内热平衡的问题,提出了适应于空间与地面环境特性的低吸收-低发射率热控涂层材料体系,采用铝粉与有机硅树脂为主要制备原材料,通过Bruggeman模型有效介质理论与Fresnel公式计算出体积分数与涂层反射率之间的变化规律,最后制备了不同配比的热控涂层,并进行了热辐射性能测试。结果表明:低吸收-低发射率型热控涂层太阳吸收比α_S=0.15、半球发射率ε_H=0.15;涂层的铝粉填料占比越高,热辐射性能越低,该规律符合体积分数与涂层反射率之间的模拟计算结论。     

环氧改性有机硅/Al-Sm_2O_3复合涂层的耐温性能

以Al粉、Sm_2O_3为颜料,环氧改性有机硅为黏合剂,采用喷涂法制备了环氧改性有机硅/Al-Sm_2O_3复合涂层。研究了不同耐热温度及耐热时间对涂层外观、微结构、近红外反射率、红外发射率及力学性能的影响。结果表明:所制备涂层在300℃下热处理5 h后,其外观、微结构保持不变;发射率和1.06μm近红外反射率可分别低至0.607和64.7%;涂层的硬度、附着力和耐冲击强度等力学性能可分别保持在4 H、1级和50 kg·cm;所制备涂层在250℃下热处理100 h后,其外观、微结构仍然保持不变;发射率和1.06μm近红外反射率可分别低至0.624和67.1%;涂层的硬度、附着力和耐冲击强度等力学性能可分别保持在4 H、1级和50 kg·cm。     

降低表面温度和发射率抑制排气系统红外辐射的研究

为了降低涡扇发动机轴对称排气系统的红外辐射特征,研究了降低排气系统腔体表面温度和发射率抑制红外辐射的规律。首先通过模拟实验研究了对中心锥进行冷却和涂覆低发射率涂层的红外抑制效果;然后用实验数据对本文使用的红外辐射特征计算方法和程序进行了验证;最后通过数值计算研究了典型尺寸的涡扇发动机排气系统降温和发射率分布对红外辐射特征的影响规律。结果表明：降低中心锥等部件的温度和发射率可明显降低排气系统在α〈15°范围内的红外辐射强度;若中心锥的温度降低100K,中心锥、涡轮和径向稳定器等部件的表面发射率降至0.2,则排气系统尾向的红外辐射强度可降低40%以上,探测距离缩短20%左右。     

低发射率材料涂敷方案对排气系统红外特性的影响

为了研究低发射率材料涂覆方案对排气系统红外特性的影响,建立了航空发动机排气系统模型,制定4种低发射率材 料涂敷方案,将涂敷部位的发射率分别设置为0.3和0.1,针对低发射率材料对航空发动机排气系统3～5 μm和8～14 μm波段的红 外辐射特性的影响进行数值仿真。结果表明：涂敷低发射率材料对排气系统3～5 μm和8～14 μm波段的红外辐射均有明显抑制 作用;在3～5 μm和8～14 μm波段,最优的涂覆方案对红外辐射强度最大值的抑制效果可达56%与37%。对排气系统中的加力 筒体、喷管等部位涂敷低发射率材料,在3～5 μm波段会增大其有效红外辐射强度,在8～14 μm波段会减小喷管的有效红外辐射 强度,增大加力筒体的有效红外辐射强度。     

多弧离子镀Cr/Cr2O3薄膜红外及可见光谱特性

采用多弧离子镀制备了具有不同色彩的Cr/Cr2O3薄膜,利用紫外-可见光分光光度计研究了薄膜在可见和红外波段的光谱特性,利用SEM进行薄膜表面结构和形貌的分析,利用四探针测阻仪测试了样品的方块电阻,利用红外发射率测量仪测试了样品的红外发射率。结果表明:Cr/Cr2O3薄膜具有丰富的色彩,在可见光区有明显的反射峰,可见光区光谱特性主要受膜厚的影响,方块电阻随膜厚增加而有变大,样品的红外发射率主要取决于金属层,平均红外发射率最小降至0.371。     

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。     

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.     

基于飞机油箱模型形状特征油量测量切片步长选择方法研究

 在分析飞机数字式油量测量过程中目前广泛使用的切片法油量测量原理的基础上,针对现有的定步长切片法无法得到准确、可靠的燃油质量特性数据库的缺陷,结合对飞机油箱模型形状特征的分析,提出了基于飞机油箱模型形状特征的油量测量切片步长选择方法。此方法包括切片步长整体和局部选择两个过程,整体选择以实现相邻两切片平面所夹油箱模型体积近似相等为目的来确定切片步长,以体现油箱模型截面整体变化规律;局部选择以设计切片平面与截面突变平面重合或尽可能接近的方式,突出油箱截面的局部变化特征。实验结果表明：该切片步长选择方法较定步长方法能够建立更为合理、可靠的燃油质量特性数据库,从而提高了油量测量精度。     

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.      

二维翼段颤振的μ控制

 采用超声电机作为作动器来实现含控制面的翼段颤振鲁棒抑制。针对作者设计的二维翼段颤振主动抑制系统，通过理论与实验相结合的方法，建立了考虑沉浮方向阻尼和作动器模型参数不确定性的控制系统模型，设计了μ控制器，并对控制器做了降阶处理。数值仿真和风洞试验表明，μ控制器可有效地抑制颤振的发生，将颤振临界速度提高23.4%。相对于H_∞控制器，μ控制器的控制效果和鲁棒性更好。     

航空发动机管路测量数据分割方法

 为了提高航空发动机管路测量数据的反求建模效率,提出了一种区域增长分割算法。该方法主要是利用管路表面在曲面索引系数映射、主曲率映射、高斯映射上的特性,并基于均值漂移算法和遗传算法提出了区域分割算法中种子区域的选择策略。然后利用区域增长分割方法实现了对管路测量数据的分割。经过仿真和实测数据验证,所提管路分割算法具有较好的分割质量和效率。     

Abnormal Shape Mould Winding

为解决网格化芯模的缠绕问题,本文提出了复合材料面片缠绕机理;接着详细分析了面片缠绕过程中的芯模凹曲面上纤维滑线和架空现象,应用微分几何曲面理论和空间几何理论,提出判据及其解决方案;最后,针对飞机发动机进气道的缠绕成型,编制缠绕控制程序并进行相应的实验,验证了面片缠绕方法的可行性。     

Interfacial Properties Modification of Carbon Fiber/ Polyarylacetylene Composites

This work was dedicated to performing surface oxidation and coating treatments on carbon fibers (CF) and investigating the changes of fiber surface properties after these treatments, including surface composition, relative volume of functional groups, and sur- face topography with X-ray photoelectron spectroscopy (XPS) and atom force microscopy (AFM) technology. The results show that, after oxidation treatments, interfacial properties between CF and non-polar polyarylacetylene (PAA) resin are remarkably modified by removing weak surface layers and increasing fiber surface roughness. Coating treatment by high char phenolic resin solution after oxida- tion makes interface of CF/PAA composites to be upgraded and the interfacial properties further bettered.     

Thermal Stresses and Cracks During the Growth of Large-sized Sapphire with SAPMAC Method

本文利用有限元法对冷心放肩微量提拉法(SAPMAC)生长大尺寸蓝宝石单晶过程中的热应力进行了模拟计算,应用临界缺陷理论解释了裂纹的萌生与扩展机理。研究表明,晶体内的热应力主要与晶体生长速率,环境温度和结晶取向有关;较大热应力多出现在结晶界面,放肩、收尾以及直径急剧变化等位置;最大热应力总是出现在籽晶与新生晶体的界面附近。裂纹将在临界缺陷位置产生,并在应力作用下沿a或m面扩展。计算结果与实验结果基本吻合,通过晶体生长系统和生长工艺的改进,对晶体的开裂问题得到了有效的抑制。     

Optimization Design System for Composite Structures Based on Grid Technology

To solve the topology optimization of complicated multi-objective continuous/discrete design variables in aircmit structure design, a Parallel Pareto Genetic Algorithm （PPGA） is presented based on grid platform in this paper. In the algorithm, the commercial finite element analysis （FEA） software is integrated as the calculating tool for analyzing the objective functions and the filter of Pareto solution set based on weight information is introduced to deal with the relationships among all objectives. Grid technology is utilized in PPGA to realize the distributed computations and the user interface is developed to realize the job submission and job management locally/remotely. Taking the aero-elastic tailoring of a composite wing for optimization as an example, a set of Pareto solutions are obtained for the decision-maker. The numerical results show that the aileron reversal problem can be solved by adding the limited skin weight in this system. The algorithm can be used to solve complicated topology optimization for composite structures in engineering and the computation efficiency can be improved greatly by using the grid platform that aggregates numerous idle resources.