气路静电监测技术在涡喷发动机试车中的应用

将气路静电监测技术应用于涡喷发动机状态监控。在利用静电电压信号计算电荷信号的过程中,利用最小二乘法解决了电荷信号存在漂移趋势的问题。分析了试车过程中电荷信号及其特征参数,表明航空发动机燃烧室积碳故障能够引起静电信号特征参数出现异常变化。结合模糊数学理论并借鉴民航发动机故障图方法,建立了某型涡喷发动机试车过程中的分解决策模型,采用实际数据验证了该模型能在一定程度上解决试车过程中发动机存在的过分解和欠分解的工程实际问题。     

黄铜全流量在线磨粒静电监测实验研究

为深入了解静电监测方法对黄铜的监测能力,采用自制的全流量在线磨粒静电传感器开展黄铜的静电监测方法研究。研究了润滑条件下轴承钢-黄铜滑动摩擦荷电磨粒的产生机理并设计了磨粒静电监测系统,开展了三种尺寸的轴承钢球和黄铜球的单颗粒注入实验、双颗粒注入实验以及相同载荷、不同滑动速度的轴承钢-黄铜滑动摩擦磨损实验,对摩擦因数、静电感应信号、静电信号均方根值进行相关性分析。研究结果表明:全流量在线磨粒静电传感器具有较好的检测一致性;静电监测方法对黄铜的监测能力强于对轴承钢的监测能力;摩擦因数与静电监测信号具有相关性,在磨损阶段,静电感应信号出现脉冲尖峰与持续上升。     

静电传感器对滑油系统磨粒 电量测量方法研究

根据静电感应原理,磨粒出现在空间不同位置时,静电传感器电极感应到的电荷量相差很大,由于磨粒出现的位置是未知的,因此很难精确测量磨粒的带电量。借助数学模型,对传感器输出信号与磨粒的关系进行仿真分析。由仿真结果可知,信号的幅值与磨粒携带的电荷量以及磨粒在传感器中所处的径向位置有关;而在已知管道中滑油流速分布的情况下,脉冲宽度只与径向位置有关。提出了通过脉冲宽度确定磨粒所处的径向位置,根据传感器在该径向位置处的灵敏度获得比较准确的磨粒带电量的测量方法。通过带电油滴模拟磨粒,对该方法进行实验验证,实验结果与仿真分析结果基本重合,该方法的测量结果与通过静电计测得的结果相比,误差不超过5%。     

Characteristics analysis and experiment verification of electrostatic sensor for aero-engine exhaust gas monitoring

An electrostatic sensor is a critical component of the electrostatic monitoring system for an aero-engine gas path. In this paper, the basic principles of the electrostatic sensor are described and the materials selection process for sensor electrodes and an isolation medium is introduced. The finite element method was adopted to calculate the sensitivity distribution, and the influence of relevant structural parameters on the sensitivity distribution characteristic is analyzed. The data fitting method was employed to acquire the unified spatial sensitivity distribution functions for a given structure sensor, which provides a useful reference for the sensor’s installation location. Based on the unified function, the sensitivity distribution function along the particle moving direction and the frequency characteristic of the electrostatic sensor were acquired. Then the corresponding influence factors of the frequency properties were analyzed. An experiment platform was established to verify the model and the theoretical analysis results. Then, simulated experiments were applied to verify the feasibility and validity of the electrostatic sensor, and the experiment results provided a useful reference for the identification of abnormal particles as a characteristic of aero-engine faults.     

差分式中红外一氧化碳检测仪的研制

根据CO分子在中红外波段的吸收特性,利用红外热辐射光源(IR55)和双通道热释电探测器(LM244),研制了一种差分式CO检测仪。通过双通道锁相放大器对探测器输出的两路信号进行处理,有效地抑制了系统噪声,提高了仪器的检测精度。介绍了系统的检测原理,给出了光学系统和双通道锁相放大器的实现方案,该锁相放大器能提取的最小标准信号幅度为1 m V,移相误差小于0.2%。利用配备的体积分数为0~1×10~(-3)的CO样品,开展了气体检测实验。实验结果表明:系统的检测下限为1×10~(-5),相对测量误差小于15%。当气体体积分数为0×10~(-6)时,测得浓度的波动范围为-5.2×10~(-6)~6.2×10~(-6)。考虑静态配气时气体在气室中扩散的时间,仪器的响应时间约为58~62 s。同基于量子级联激光器和分布反馈激光器的CO检测仪相比,所研制的仪器具有结构简单、性价比高等优势,在煤矿、环保等场合的CO检测方面具有较好的应用前景。     

Identification of gas/solid two-phase flow regimes using electrostatic sensors and neural-network techniques

In the gas/solid two-phase system, solid particles can accumulate a large number of electrostatic charges because of collision, friction and separation between particles or between particles and the wall. Through the detection and processing of the induced fluctuation charge signal, a measuring system can obtain two-phase flow parameters, such as flow regime, concentration and velocity. A novel methodology via introducing the characteristics of speech emotion recognition into flow regime identification is proposed for improving the recognition rate in gas/solid two-phase flow systems. Three characteristics of electrostatic fluctuation signals detected from an electrostatic sensor are extracted as the input of back propagation (BP) neural networks for flow regime identification. They are short-term average energy, Mel-frequency cepstral coefficients (MFCC) and cepstrum. The results show that the method based on each characteristic of the electrostatic fluctuation signal and BP neural networks can identify the three flow regimes of gas/solid two-phase flow in a horizontal pipe, and the identification rate of the method based on the three characteristics and BP neural networks is up to 97%, much higher than the methods based on a single characteristic.     

织物静电电位分布测量仪的研制

研制了织物静电电位分布测量仪，由高灵敏度电压传感器、信号放大器、数据采集卡、扫描控制系统组成。可对织物或其他片状物的静电压分布进行检测。采用可视化人机对话操作界面，可实现扫描、测量及数据采集，特别适合于含导电纤维纺织品经摩擦后的静电电位分布曲线的检测，可从静电分布规律人手进行抗静电机理研究和抗静电纺织品的设计。     

航空发动机气路静电传感器优化设计与安装

航空发动机气路静电传感器的结构参数直接影响着传感器的性能。采用有限元的方法,分析了传感器的结构参数对静电传感器特性的影响规律。分析结果表明:增加传感器的感应探极,传感器的灵敏度有所提高,灵敏度分布空间也增大;随着绝缘材料的介电常数增加,灵敏度值有所增加;而绝缘材料厚度的增加将会导致灵敏度下降,且随着轴向位置增加,绝缘层厚度对灵敏度值的影响逐渐减小。对于给定结构参数的传感器,采用数据拟合的方法,获得传感器的灵敏度分布函数,基于拟合系数的变化特点来确定传感器的安装布局;最后通过模拟实验对本文的方法进行了有效性验证。     

Study on electrodynamic sensor of multi-modality system for multiphase flow measurement

Accurate measurement of multiphase flows, including gas/solids, gas/liquid, and liquid/liquid flows, is still challenging. In principle, electrical capacitance tomography (ECT) can be used to measure the concentration of solids in a gas/solids flow and the liquid (e.g., oil) fraction in a gas/liquid flow, if the liquid is non-conductive. Electrical resistance tomography (ERT) can be used to measure a gas/liquid flow, if the liquid is conductive. It has been attempted to use a dual-modality ECT/ERT system to measure both the concentration profile and the velocity profile by pixel-based cross correlation. However, this approach is not realistic because of the dynamic characteristics and the complexity of multiphase flows and the difficulties in determining the velocities by cross correlation. In this paper, the issues with dual modality ECT/ERT and the difficulties with pixel-based cross correlation will be discussed. A new adaptive multi-modality (ECT, ERT and electro-dynamic) sensor, which can be used to measure a gas/solids or gas/liquid flow, will be described. Especially, some details of the electrodynamic sensor of multi-modality system such as sensing electrodes optimum design, electrostatic charge amplifier, and signal processing will be discussed. Initial experimental results will be given.     

一种温、湿度及静电测试仪

静电及温、湿度检测报警装置是对静电的检测并对危险的情况及时给出报警信号。在爆炸性危险场所,静电的测量是静电防护工作中重要组成部分,而环境条件特别是环境的温度、湿度对静电性能的测量有较大影响。该测试仪采用温、湿度及静电传感器直接测量装配空间的温度、湿度和带电物体的静电电压(电位),采集信号经过放大器和A/D转换器等,由液晶显示出装配空间的温、湿度以及被测物体的静电电压。     

定容式粉体静电在线监测仪的设计

介绍了一种可实现与DCS系统通讯的粉体静电在线监测仪。它利用定容式法拉第筒原理，即在管道旁路中放置法拉第筒结构的定容电荷室。通过控制装在定容电荷室下面的电磁阀，实现对粉体的在线采样。通过建立粉体荷质比和静电监测仪输出电压之间的关系，实现对粉体荷质比的直接测量。该粉体静电监测仪能够实现对粉体静电的实时、在线、远程监测。这种方法比直接测量静电电压和静电电场的方法具有更高的精度，同时它弥补了DQJ-2粉体静电监测器需要手动操作的不足。定容式粉体静电在线监测仪和静电消除器配套使用，可以有效地对静电电量进行监测和消除，减少燃爆事故的发生，保证企业的安全生产。     

A cryogenic circulating advective multi-pass absorption cell

A novel absorption cell has been developed to enable a spectroscopic survey of a broad range of polycyclic aromatic hydrocarbons (PAH) under astrophysically relevant conditions and utilizing a synchrotron radiation continuum to test the still controversial hypothesis that these molecules or their ions could be carriers of the diffuse interstellar bands. The cryogenic circulating advective multi-pass absorption cell resembles a wind tunnel; molecules evaporated from a crucible or injected using a custom gas feedthrough are entrained in a laminar flow of cryogenically cooled buffer gas and advected into the path of the synchrotron beam. This system includes a multi-pass optical White cell enabling absorption path lengths of hundreds of meters and a detection sensitivity to molecular densities on the order of 10(7) cm(-3). A capacitively coupled radio frequency dielectric barrier discharge provides ionized and metastable buffer gas atoms for ionizing the candidate molecules via charge exchange and the Penning effect. Stronger than expected clustering of PAH molecules has slowed efforts to record gas phase PAH spectra at cryogenic temperatures, though such clusters may play a role in other interstellar phenomena.     

Note: He puff system for dust detector upgrade

Local detection of surface dust is needed for the safe operation of next-step magnetic fusion devices such as ITER. An electrostatic dust detector, based on a grid of interlocking circuit traces biased to 50 V, has been developed to detect dust on remote surfaces and was successfully tested for the first time on the National Spherical Torus Experiment. In this note, we report a helium puff system that clears residual dust from this detector and any incident debris or fibers that might cause a permanent short circuit. Two consecutive helium puffs delivered by three 0.45 mm nozzles at an angle of 30° cleared the entire 5 cm × 5 cm surface of the detector.     

基于波长调制技术的甲烷气体浓度检测的研究

与谐波检测相结合的波长调制技术是目前检测有害气体的主要方法。主要是用实验的方法找到了甲烷气体在1 650 nm附近的一根吸收线,然后采用正弦信号对激光器的驱动进行了调制,实现了甲烷气体浓度的谐波检测。用锁相放大器RS830来提取二次谐波,然后根据锁相放大器的原理,用LabVIEW软件实现了锁相放大器的设计,来提取一次谐波信号,节约了成本。由气体吸收室中的GRIN透镜引起的标准具效应是影响检测灵敏度的主要原因,最后对该噪声和其他可能的影响进行了分析。     

激波探测系统传感器信号调理电路设计

采用压电式传感器测量激波信号时,由于其检测到的激波声压信号弱,输出为微电流,一般的信号调理电路不能满足要求,基于此问题,开展针对激波的信号调理电路的研究,该电路主要由电荷放大电路、带通滤波电路、输出放大电路等组成,其中带通滤波器的带宽设计为3～8 kHz,选用高精度单片运放OP07实现;电荷放大电路选用高阻、低偏置电流...     

基于PVDF压电薄膜的冲压模具凸模监测方法

利用PVDF压电薄膜厚度薄、耐冲击、频响范围宽等特性,提出了一种能够监测冲压加工中细小凸模折断的监测方法.理论分析和模拟实验证明该方法非常适合对冲压加工中的凸模进行监测.     

驻极体空气过滤器用于燃气轮机末滤的效率特性

某燃气轮机机组使用驻极体空气过滤器作为末级过滤,一段时间后出现效率曲线快速下降、压气机水洗频率增加等异常。基于EN 779—2012标准,在EN3600实验台等试验设备上设计了褶尖检测试验和多工况效率试验。结果表明,驻极体空气过滤器静电效应随使用时长增加下降过快;对于需长期连续使用的过滤系统末级,在静电电荷逸失较快的问题未得到改善之前,应慎重选用驻极体过滤器。研究结果可为相关从业人员的设计、选型和科研提供参考。     

自聚焦光纤在油液磨粒监测中的应用

结合在线监测,根据油液中悬浮颗粒对光线的散射的特性,提出了利用双光路光纤传感器,通过检测激光透射过不同油液后的透射光强,并把测量量进行相关计算,得到油液中的磨粒信息,及时了解设备的工作状态,从而实现了对设备的实时在线状态监测。     

Effects of particle charging on electrical capacitance tomography system

A multimodal tomography system based on the electrical capacitance and electrostatic sensor arrays is proposed to investigate the effects of particle charging in the pipe on electrical capacitance tomography (ECT). The effect of the charge in the pipe on the detection circuit of ECT is firstly analyzed. Then the simulations are performed to make further investigation on the effect of the charge distribution on ECT. The simulation results indicate that the electrostatic effects on ECT vary with the spatial distribution of the charge in the pipe. The charges near the pipe wall have greater effect on ECT than those in the center of the pipe. The capacitance electrode-pairs near the charge distribution are greatly affected. Experiments are also performed on a pulley rig, which verify the simulation results.     

Multiple model-based detection and estimation scheme for gas turbine sensor and gas path fault simultaneous diagnosis

In this paper, a multiple model (MM)-based detection and estimation scheme for gas turbine sensor and gas path fault diagnosis is proposed, which overcomes the coupling effects between sensor faults and gas path faults, and simultaneously realizes an accurate diagnosis of sensor and gas path faults. First, an adaptive fault detection and isolation (FDI) framework based on the MM method was established to detect and isolate sensor faults and gas path faults. Then, a fault amplitude estimation method was proposed according to the FDI results, and a fault validation method based on the Chi-square test was proposed to confirm the actual fault. Finally, hardware in the loop (HIL) simulation platform was established to validate the effectiveness of the proposed method. Several simulation case studies were conducted based on a two-shaft marine gas turbine with common gas path faults and sensor faults. The simulation results show that the proposed method can accurately diagnose the fault and estimate the corresponding fault amplitude when both the sensor fault and the gas path fault coincide.