风扇/压气机周向模态识别中传感器角度偏差的影响

基于任意角度压缩感知(CS)方法分析了传感器安装角度偏差对风扇/压气机周向模态识别重构的影响,设计了一套自适应角度优化程序修正重构误差。利用数值试验探究了传感器角度偏差和数量对周向模态重构结果的影响,研究表明:当角度偏差等级为2.5%时,平均重构误差达到10%以上,若保证重构误差基本不变,将传感器数量从7个增加至25个,仅可以将角度偏差等级放宽至4%。而采用小生境微种群遗传算法进行自适应角度优化,在20 dB信噪比下,通过自适应角度优化可将角度偏差等级从2.5%放宽至10%,降低了传感器安装的精度要求。成功优化了一款冷却风扇在前三阶叶片通过频率下的主要周向声模态重构幅值。自适应角度优化算法有效提升了基于压缩感知的风扇/压气机周向模态重构可靠性。     

高温高速气流总焓接触测试法对比分析

发动机尾焰、燃烧加热、电弧加热器等高温高速气流总焓测量存在较大误差,采用结构优化的质量吸入水冷焓探针,标定后的驻点热流和驻点压力探针(Fay-Riddell公式法)对高温高速气流总焓进行了对比测试。结果表明:焓值为2.5~5 MJ/kg时,焓探针的测试误差约为3.38%,采用Fay-Riddell公式法获得焓值的误差约为3%。焓探针与Fay-Riddell公式法平均偏差约为4.65%。在地面模拟试验时采用两种测焓方法确定测试精度,对减小高温高速气流测焓误差,提高试验模拟精度具有积极的作用。     

Corrosion mechanism investigation of TiN/Ti coating and TC4 alloy for aircraft compressor application

It is imperative to develop multifunctional erosion and corrosion resistant coatings for compressor blades of aircraft engines in harsh environment. PVD (Physical Vapor Deposition) technology has the advances in processing erosion-resistant coatings; however, the performance of PVD coatings to combat corrosion depends on various coating defects. Determining and comparing the corrosion performances of PVD TiN/Ti coating and uncoated TC4 alloy was the main objective of present work. The 960 h salt spray corrosion and 116 h hot corrosion tests were conducted to simulate the grounding and working environments of the aircraft compressors. The corrosion mechanisms due to the coating defects such as pinhole, columnar boundary and large grain were analyzed based on the OM, Confocal microscope, electrochemical measurements, SEM, XRD and EDS results. Owing to the disordered state associated with the columnar boundary and the coating defect, nitrogen could be easily replaced by oxygen in the hot corrosion process, these structures were channels for fast diffusion of oxygen. Moreover, the Gibbs energy changes of Ti oxidation and TiN oxidation were thermodynamically calculated according to the working condition of aircraft compressors, and considerable research effort was focused on mapping out the phase diagram of Ti, TiN and high pressure gases. The findings of this research can provide insights into developing multifunctional coatings for future aircraft engines.     

Optimization and verification of free flight separation similarity law in high-speed wind tunnel

Based on the similarity of separation time, a similarity law optimization method for high-speed weapon delivery test is derived. The typical separation state under wind load is simulated by the numerical method. The real separation data of aircraft, separation data of previous test methods, separation data of ideal wind tunnel test of previous methods, and simulation data of the proposed optimization method are obtained. A comparison of the data shows that the method proposed can improve the performance of tracking. Similarity law optimization starts with the development of motion equations and dynamic equations in the windless state to address the problems of mismatching between vertical and horizontal displacement, and to address the problems of separation trajectory distortion caused by insufficient gravity acceleration of the scaling model of existing light model. The ejection velocity of the model is taken as a factor/vector, and is adjusted reasonably to compensate the linear displacement insufficiency caused by the insufficient vertical acceleration of the light model method, so as to ensure the matching of the vertical and horizontal displacement of the projectile, and to improve the consistency between the test results of high-speed projection and the actual separation trajectory. The optimized similarity law is applicable to many existing free-throwing modes of high-speed wind tunnels. The optimized similarity law is not affected by the ejection velocity and hanging mode of the projectile. The optimized similarity law is suitable not only for the launching of the buried ammunition compartment and external stores, but also for the test design of projectile launching and gravity separation.     

用于光波纳米推力器的颗粒供应技术和光聚积技术研究

为提高光波纳米推力器在轨应用的可行性,针对与其匹配的颗粒供应技术和光聚积技术进行研究。提出整个推进系统的设计思路,通过建立理论计算和数值计算模型,分析颗粒供应技术和光聚积技术的各项核心结构参数的设计方法。计算结果表明:颗粒供应装置的正负电极内径之比(W/D)会影响正负电荷产生的总量之比,在W/D=300/322附近时,正负电荷比例接近1:1。静电诱导电压为9 V,当中和通道长度大于37.5mm时,正负颗粒可以视为完全中和。光聚积设计思路可令聚积球对光能的利用率在32.8%左右。两种相关技术的装置与推力器在结构上能够对接、在性能上可以匹配,从理论上表明了两种支撑技术的可行性。     

舰载直升机理论风限图飞行模拟获取方法

获取舰载直升机实用风限图,仅依靠实装飞行试验或建模仿真都是非常困难的。通过起降飞行模拟试验获取理论风限图,结合少量的海上实装飞行验证试验是一种综合较优的方法。起降飞行模拟试验需要真实飞行员和高等级飞行模拟器参与,飞行模拟器中的母舰气流场数据、母舰运动可由建模仿真或试验测试得到,且必须考虑母舰气流场的非定场特性;只有当飞行员视景或视觉反馈受限时(如能见度降低时),飞行模拟器基座的六自由度运动才是必需的;用DIPES或Bedford方法量化飞行员主观操纵负担,结合记录的客观操纵数据,评判起降难度;典型的飞行模拟试验程序包含了不同风况下的进近和甲板着舰,通常每隔15°和5kn一个风况。通过起降飞行模拟试验得到的理论风限图,可以更加有效和安全地指导海上实装飞行验证试验,最终获得实用风限图。     

三脉冲冷原子陀螺仪中基于内态演化的拉曼光光强补偿算法

由于在复杂环境中拉曼光功率不稳定会导致原子脉冲的宽度发生改变,从而影响陀螺仪的测量精度.通过对冷原子干涉仪的干涉全过程进行建模,计算得出了陀螺仪在拉曼光改变情形下输出相位的解析表达式,即建立了拉曼光在非近共振条件下强度变化时陀螺仪的输出值与外界载体运动之间的关系.与此同时,基于该解析表达式提出了一种对拉曼光光强的补偿算...     

A swept fin-induced flow field with different height mounting gaps

In order to apply the air fin successfully and ensure the maneuverability of hypersonic vehicle, a key problem to be studied urgently is the heat flux brought by the fin mounting gap. The appearance of mounting gap and fin shaft can induce many complex flow structures which need more attentions to be investigated. Under Ma 6, Nano-tracer-based Planar Laser Scattering (NPLS) and Temperature Sensitive Paints (TSP) were applied to visualize and measure transient flow structures and heat flux distribution of a swept fin-induced flow field with different height mounting gaps. Complementarily, Reynolds-averaged N-S equations were solved with k-ω SST turbulent model. The heat flux distribution results of numerical simulation and TSP observed the change of high heat flux region with different mounting gap, both in position and magnitude. The streamlines based on Computational Fluid Dynamics (CFD) and flow visualization results obtained by NPLS revealed the cause of high heat flux region. The high heat flux region in this flow field is mainly related to the reattachment of vortex and flow stagnation. The increase of gap height can lead to stronger gap overflow and shaft-induced horseshoe vortex, which are source of the high heat flux around the fin. The case with the highest mounting gap (4 mm) en-counters the most severe aerodynamic heating, both on the surface of fin and plate. Thus, under the premise of ensuring the flexibility of the fin, the gap should be set as small as possible.     

石墨填料对浸渗热解-熔融浸渗方法制备的C/SiC复合材料结构和性能的影响

采用石墨树脂浆料浸渍三维针刺碳毡增强体,热解后得到C/C多孔体,并采用反应熔体浸渗法制备C/SiC复合材料.研究了石墨填料对C/C多孔体的结构以及C/SiC复合材料力学性能的影响.结果 表明,石墨树脂浆料浸渍时树脂填充束间小孔形成结构致密的亚结构单元,而石墨可以有效填充胎网层等大孔隙,一次浸渍热解后碳产率有效提高.所得...     

冲偏出跑道事件风险影响指标分析

目前对冲偏出跑道风险的研究多基于事故统计数据,较少从飞行数据及飞行操作特征的角度进行分析。基于飞行数据,对冲偏出跑道事件开展风险分析。将飞行数据分为飞行状态、操作指令、信息3 类,以此研究飞机在起飞滑跑、着陆、着陆滑跑3 个阶段的状况及风险影响指标;通过数据所反映的操作特征,结合标准操作程序,推导出飞机偏离正常数据、与标准操作不相符的操作,得到影响正常飞行的风险因素;基于行为安全2-4 模型,建立冲偏出跑道风险评价指标体系,对实际案例的事故致因机理进行研究,着重分析操作特征及人为因素,并提出冲偏出跑道风险防控措施。结果表明：通过对飞行操作特征及飞行参数的分析,从操作类、数据类以及环境类3 个维度建立风险影响指标体系,可以降低指标因素对冲偏出跑道事件的影响;从人、机、环、管方面提出改进措施,可有效降低冲偏出跑道事件发生的概率。