高度局域线偏振时空光涡旋的生成方法

携带横向轨道角动量的时空光涡旋是一种新型光脉冲波包,受到越来越多的关注。本文报道一种经过高数值孔径透镜聚焦,在透镜焦平面上产生偏振态可控的线偏振时空光涡旋的方法。为克服聚焦透镜对入射时空涡旋产生的时空像散效应,需对入射时空波包作预劈裂处理。基于Richards Wolf矢量衍射公式仿真了不同偏振态下的高度局域时空涡旋的三维时空场分布,并对其强度和相位特性进行了分析。生成的水平偏振、垂直偏振以及45°偏振高度局域时空涡旋证明了本文所提方法的有效性。     

金属纳米线阵列红外偏振器

本文用电磁场理论推导了多排金属纳米线有序阵列的光学损耗表达式，并进行了数值模拟。采用电化学沉积工艺将金属银电镀到氧化铝的孔中，得到含银纳米线氧化铝膜有序阵列复合结构，测量了含银纳米线氧化铝膜的光学损耗。理论和实验研究表明，含银纳米线氧化铝膜有序阵列的光学损耗显著依赖于光的偏振方向，在红外波段表现出良好的偏振特性，是一种新型红外微偏振器。     

基于局域表面等离子体共振的近场偏振测量

在近场条件下金纳米粒子能引起光场矢量局部变化,针对金纳米粒子的这一特性,提出了一种检测近场光偏振态的新方法。将半径为50 nm的金纳米小球组成金纳米粒子阵列结构,利用该结构产生一定的光强分布图案,用于检测不同偏振态的光场矢量。利用数值模拟软件FDTD对金纳米粒子阵列结构进行模拟仿真,结果表明,从仿真图案上可以直观地分辨出5种不同偏振态的光场。     

强度调制偏振光谱仪的系统设计

理论分析和实验研究了强度调制偏振光谱仪系统参数的设计。介绍了强度调制偏振光谱仪的结构原理,分析了调制器设计、光谱仪选型与系统指标间的匹配关系。给出了一个完整的设计实例,以搭台方式建立了强度调制偏振光谱仪原理实验装置,并对平行光管直接输出的光和经起偏器起偏后输出的光进行了偏振光谱测量和分析。结果表明:在有效测量波段内(525～700nm),以卤钨灯为光源的平行光管直接输出光的偏振度值10%;经过线偏振器起偏后输出光的偏振度值接近100%,与理论分析的结果一致,验证了基于强度调制技术设计偏振光谱仪方法的可行性。     

光纤迈克尔逊干涉仪的理论与应用分析

介绍了光纤传感器,特别是干涉式光纤传感技术的优点。给出了光纤Michelson干涉仪系统的结构。重点给出了光纤Michelson干涉仪系统中信号光与参考光干涉原理以及影响干涉光强因素的理论分析。详细阐述了单模光纤偏振控制器结构、工作原理以及其对光纤Michelson干涉仪系统传感臂偏振态的控制。最后,给出了光纤Michelson干涉仪系统的应用分析。     

基于DSP的偏振光位移传感器

提出了一种新型偏振光直线位移传感器的DSP实现。基于光的偏振特性、马吕斯定理和法拉第旋光效应,采用同光源双光路检测,实现了大量程直线位移的测量。     

集成多测量技术的自动检测系统

介绍了现有接触式测量技术与非接触式光学测量技术的优缺点。为了实现工业产品的高精度高效测量,提出了一种新型的自动检测系统。此系统在三坐标测量机上集成了视觉系统和锥光偏振全息光学测量系统,并可根据不同的精度要求和零件结构选择适当的测量装置。文章介绍了系统的总体方案以及核心模块。     

新型聚合物光可变衰减器阵列

光可变衰减器是密集波分复用网络中的重要器件之一。介绍了一种新型聚合物光可变衰减器 (VOA)的设计方法 ,利用聚合物的热光效应 ,动态范围可达 2 5 d B。这种新型聚合物 VOA不仅体积尺寸小 ,插入损耗小 ,功耗低的优点 ,而且表现出良好的偏振独立性 ,对该器件进行了相关性能的分析和模拟     

新型聚合物光可变衰减器阵列

光可变衰减器是密集波分复用网络中的重要器件之一.介绍了一种新型聚合物光可变衰减器(VOA)的设计方法,利用聚合物的热光效应,动态范围可达25dB.这种新型聚合物VOA不仅体积尺寸小,插入损耗小,功耗低的优点,而且表现出良好的偏振独立性,对该器件进行了相关性能的分析和模拟.     

新型聚合物光可变衰减器阵列

光可变衰减器是密集波分复用网络中的重要器件之一.介绍了一种新型聚合物光可变衰减器(VOA)的设计方法,利用聚合物的热光效应,动态范围可达25dB.这种新型聚合物VOA不仅体积尺寸小,插入损耗小,功耗低的优点,而且表现出良好的偏振独立性,对该器件进行了相关性能的分析和模拟.     

Optical investigation of the fuel injector influence in a PFI spark ignition engine for two-wheel vehicles

This paper describes the results obtained in a port fuel injection spark-ignition (PFI SI) engine by optical diagnostics during the fuel injection and the combustion process. A research optical engine was equipped with the fuel injection system, the head and the exhaust device of a commercial 250 cc engine for scooters and small motorcycles. Two injectors were tested: standard 3-hole injector that equipped the real reference engine and a 12-hole injector. The intake manifold was modified to allow the visualization of the fuel injection using an endoscopic system coupled with CCD camera. Size and number of the fuel droplets were evaluated through an image processing procedure. The cycle resolved visualization and chemiluminescence allowed to follow the combustion process from the spark ignition to the exhaust phase. All the optical data were correlated with engine parameters and exhaust emissions. The effect of the fuel injector type on deposits formed by fuel accumulation and dripping on the intake valves steams and seats was investigated. In particular, the evolution of diffusion-controlled flames due to the fuel deposits burning was analyzed. These flames were principally located near the intake valves, and they persisted well after the normal combustion event. The consequences were the formation and emission of soot and unburned hydrocarbons. The multi-hole injector helped reducing wall wetting and deposit formation so that the emission characteristic can be improved. The use of 12-hole injector allowed a more homogeneous distribution for a lower time of fuel droplets in the intake manifold than the 3-hole injector. This study also investigated the detailed physical/chemical phenomena to figure out reasons for the improvement using optical measurements.     

Cylinder Liner Surface Analysis During SI Engine Break-In

Surface texture of an engine cylinder liner at the top-ring reversal point was observed by using Scanning Electron Microscopy (SEM) and optical microscopy. Experiments were conducted on a single-cylinder spark ignition engine over the engine break-in period. The surface texture of the cylinder liner was observed before and after the break-in test. The changes of surface texture and the wear mechanisms during the engine break-in were analyzed. The primary wear mechanisms were found to be abrasion and plastic deformation.     

基于角域振动信号特征统计量的发动机故障分类方法

为了提高发动机故障分类的准确率和成功率,提出了基于角域信号特征统计量的发动机故障分类方法。包括：利用编码器进行发动机振动信号的等角度采样;采用小波包分析和相关系数法获取发动机角域信号的特征阶次;选取特征阶次信号的能量比、标准差比、谱能量比及谱均值比4组参数作为角域信号特征统计量来提取发动机故障特征;采用支持向量机法对发动机故障进行分类。连杆轴承配合间隙故障的台架试验结果证明:相比于传统的分类方法,该方法明显提高了发动机故障分类的准确率。     

Optical Diagnosis of the Geometry of an Axisymmetric Controlled Nozzle of a Gas-Turbine Engine

Modern aviation industry solves the problem of developing multifunction engines capable of flying both at subsonic and supersonic speeds. An important part in such engines is a variable area nozzle, which allows varying the geometry of the engine exhaust unit and, accordingly, its technical characteristics. This study touches upon an computer vision based optical noncontact method for reconstructing a nozzle shape. The reconstruction requires data recorded by two optical three-dimensional recorders directed toward the inner part of the nozzle when the engine is subjected to ground tests. The diagnosis is complicated by the presence of a hot jet being in the way of the sensor vision, the regime-dependent variation of the nozzle glow brightness, and intense mechanical vibrations. The performed bench tests confirm the efficiency of the proposed method. According to their results, in a low-gas regime, the standard deviation of the diagnosed diameters of the exhaust unit and critical sections for each frame does not exceed 0.3% of the corresponding sizes. The data obtained as a result of this diagnosis can be taken into account when upgrading the exhaust unit of the engine and the thrust control system of a gas turbine engine.

     

普通量仪测量凸轮的方法构思及测点坐标求解

论述了在通用光学测量仪器(“万工显”、“大工显”、投影仪)上,采用影像法模拟直动对心式(或偏置式)滚柱测头、刀口测头、平面测头测量发动机凸轮的方法.分析和实践表明,该方法测量简便、快速、准确度高,满足了没有专用凸轮测量仪的非专业生产厂家发动机凸轮精密测量的需要.     

超燃发动机流场组分浓度的在线测量

为了正确评价超燃发动机试验状态,采用自发拉曼散射技术在线测量了超燃发动机流场的主要组分。基于发动机试验条件和发动机与光学诊断技术的接口,建立了用于发动机流场组分测量的自发拉曼散射实验系统;测量了多车次发动机试验过程中流场主要组分的拉曼光谱;最后,通过光谱计算获得了流场主要组分浓度信息并重点分析了来流氧气含量及其变化情况。实验显示:发动机试验中,部分车次试验补氧后的来流中氧气的最大含量达到了30%,最小含量为18%,说明发动机试验过程中,对补氧量的控制精确和稳定性还有待提高。结果表明:采用自发拉曼散射技术可以较好地完成来流主要组分浓度测量工作,测量结果可用于发动机试验数据的分析及来流补氧控制方式和控制精度的改进。     

Fibre Optic Sensors for Long-Term Monitoring of Oil Film Pressure in Diesel Engine Main Bearing

The oil film pressure is one of the key parameters in journal bearings influencing the performance of the bearings. A fibre optic sensor was developed for online determination of actual oil film pressure under load without disturbing the actual tribological contact. Four optical sensors were integrated in a hydrodynamic journal bearing of a Wärtsilä Vasa 4R32 LN E medium-speed diesel engine with four cylinders, maximum power of 1,640 kW and rotating speed on 750 rpm. Online engine tests were carried out with different loads to study the sensor operation in real operating conditions. The engine tests were repeated six times over 4 years of operation reaching up to thousand hours of the engine use. The results showed differences in bearing pressure depending on the position of the sensor and on the operating cycle of the cylinders. The pressure peaks of all four cylinder work cycles could be identified in the measured pressure curves, and the pressure variations within the pressure curves fit well to the diesel engine’s work cycle and mass forces. The sensors had good repeatability over the whole test period.     

YZ4105ZQ增压柴油机用复合材料活塞

为满足YZ4105ZQ型废气涡轮增压柴油机对活塞的使用要求,研制液态模锻法生产陶瓷短纤维局部增强铝基复合材料活塞,采用金相显微镜观察复合材料增强部位的金相组织,测试复合材料的高温力学性能,并采用扫描电镜观察拉伸断口形貌；复合材料活塞装机后进行了600h台架可靠性试验和500h台架热冲击试验。试验结果表明,复合材料活塞的增强部位纤维分布均匀,与未增强的活塞裙部界面结合过渡平缓,陶瓷纤维与铝基体之间的结合良好；体积分数为15％的Al_2O_(3f)/ZL109复合材料在613K的高温抗拉强度达到132MPa,比未增强基体铝合金高50％左右；使用复合材料活塞装机的YZ4105ZQ增压柴油机,通过了600h台架可靠性试验和500h热冲击试验,整机的性能指标优于设计要求；复合材料活塞的尺寸稳定性、耐磨性等均表现良好,符合装车要求。     

A study on the measurement of temperature and soot in a constant-volume chamber and a visualized diesel engine using the two-color method

In this study, the measurements of soot and temperature were used to investigate the turbulent diesel diffusion flame in a constant-volume chamber and a visualized direct injection (D.I.) diesel engine using the two-color method and a high-speed camera. Through these experiments, we effectively acquired information on the temperature and soot by the two-color method in a turbulent diesel diffusion flame. In addition, this experiment revealed that the KL factor was high on the parts of the chamber where the temperature dropped. On the other hand, the KL factor was low where the temperature increased rapidly. Also, the highest temperatures of the flame in a constant-volume chamber and in a D.I. diesel engine were approximately 2300K and 2400K, respectively. This study suggests the measurement of not only the temperature but also the soot of a diffusion flame of the diesel engine through an optical methodology.     

孔探检测在航空发动机维护中的应用

发动机孔探检查,就是借助工业内窥镜,对发动机的内部结构进行检查,定期监测发动机部件工作状况、及时发现损伤缺陷,以评估发动机的整体性能和健康状况,为航空发动机的安全运行和维修工作提供可靠的技术依据。