阵列式静电传感器结构设计与优化研究

气固两相流广泛存在于自然界和工业生产过程中,利用阵列式静电传感器感应成像系统可以对两相流的流型、截面分布等信息进行可视化监测,进而得到其流动特性、运输效率、安全状况等情况,对于两相流体的理论研究以及相关生产过程的安全化、高效化和实时控制等具有重要意义。本文提出了一种新型的阵列式静电传感器结构,通过有限元方法分析静电传感器敏感场特性,进而验证传感器的结构参数对测量结果的影响;建立了两相流流动的仿真模型,通过对比传感器不同结构参数下的敏感特性,对相关参数进行优化,对提高静电成像系统的成像精度与准确度具有重要意义。     

基于阵列式静电传感器的密相气力输送表观气速测量方法研究

高压密相气力输送是加压气流床煤气化的关键技术之一,对其表观气速的测量是监测其流动状态变化的重要依据,目前主要采用测量温度、压力、流量等参数进行间接计算的方法获取。本文提出一种基于阵列式静电传感器直接测量的新方法,利用阵列式静电传感器局部敏感特性,通过对每个电极获取的静电信号进行EMD分解得到其多尺度能量比,进而提取出其高频高能分量,并进行功率谱分析和等效频率计算,对各电极的等效频率进行加权平均从而获取加权频率,进而建立加权频率与表观气速的关系。通过对3种粒径褐煤煤粉输送的实验验证,结果表明该方法可行,能够建立加权频率与表观气速的线性关系,并且该线性关系的斜率随着输送颗粒粒径的增大而减小,同时也为测量颗粒粒径提供了新的手段。     

用于形貌测量的反射式光纤传感器研究综述（英文）

区别于传统接触式表面形貌测量技术,光纤传感器具有非接触无损检测等独特优点。本文简要介绍了用于测量表面形貌的反射式强度调制光纤传感器(RIM-FOS)的原理及性能特点,并与其他几种主流形貌测量方法对比。综述其在表面形貌测量中的应用与发展过程,分析反射式光纤传感器在表面形貌测量中热点问题的研究现状,总结并展望今后的发展趋势。     

基于静电传感器的气固两相流质量流量测量方法的研究

固相微粒的体积浓度和平均速度是测量两相流质量流量的2个关键参数。本文研究了基于静电传感器的双参数法测量质量流量的新方法。对体积浓度的测量,首先通过对系统等效电路的分析及求解泊松方程并结合体积浓度与空间电荷密度的关系,建立了传感器输出电压与体积浓度之间的数学模型,而对固相速度的测量则采用了波形法,记录通过上、下游传感器的时间差,计算出固相速度。在得到固相体积浓度与速度的基础上,由质量流量的计算公式即可得到两相流的质量流量。     

振动传感器信号调理电路设计及分析（英文）

基于压电式传感器能把振动或冲击的加速度转换成与之成正比的电荷这一原理,提出了该类型传感器的等效电路。设计了基于采集测量系统的压电式传感器电荷/电压转换电路,分析了电路中关键元器件——反馈电容的温度特性对于转换电路输出的影响,对不同类型滤波器进行了特性分析,并根据实际传感器带宽配置了相应滤波电路。通过试验表明,该信号调理电路能有效滤除振动信号中的噪声信号,并能获取精确的振动信号。     

用于气固两相流流量测量的阵列式电容传感器和互相关测量系统

在电力、冶金、化工等工业生产过程中,大量存在气固两相流流动情况。气固两相流的流量测量对于计量、节能和控制具有重要意义。本文设计了阵列式电容传感器、信号测量电路和以ＭＣＳ—８０９８单片机为核心的智能互相关测量系统。通过在气固两相流试验装置上的试验研究表明,设计的测量系统可以用于直接测量气固两相流中分离相的速度、浓度和质量流量,该系统有较高的实时性和测量精度。     

基于ANSYS的润滑油路静电传感器建模与仿真特性分析北大核心CSCD

静电传感器的感应与监测性能与其特性参数相关,利用理论方法进行数学建模与计算是一种较有效的方法,但模型构建的难度较大。因此,采用基于有限元的建模和仿真研究方法,该方法可以对润滑油路静电传感器结构材质进行设定且无须通过复杂的理论公式推导。仿真结果表明:空间灵敏度在探极感应面中心区域内变化较明显;传感器效率随探极长度与直径比值增大而增大。仿真结果与理论模型计算结果变化趋势相一致,且更精确直观,对后续使用有限元方法研究结构更复杂的静电传感器的性能提供参考。     

一种研究线性霍尔传感器频率响应特性的测试平台（英文）

线性霍尔传感器被广泛用于测量磁场强度,但针对霍尔传感器动态响应特性的研究却很少。为此,设计并搭建了一种线性霍尔传感器的频率响应特性测试平台。该平台由可控恒流源、线圈、线性霍尔传感器、低噪声放大器和数据采集装置组成,通过构建系统传递函数并提出动态更新的传递函数的方法,实现了霍尔传感器动态响应特性的精确测量。利用该平台分别测试了NHE520F和P3A两款芯片的动态特性性能。结果显示,在2.5 kHz-2 MHz范围内,这两款霍尔传感器在幅频特性和相频特性方面的性能差异在测试平台上被充分显现,而且霍尔传感器的动态特性参数与静态特性参数并非必然一致,动态特性分布也不相同。此外,根据多种温湿度条件下测得的霍尔传感器幅频特性与相频特性,绘制了霍尔传感器的平均动态特性曲线和3个标准差包络曲线。基于该测试平台获得的实验数据对研究霍尔传感器动态响应特性具有重要意义。     

网状静电传感器弯管处颗粒速度与浓度的测量

为了对气力输送管道进行实时监控,并且提高炉膛内的燃烧效率,需要对气力输送管道中颗粒的速度与浓度分布进行测量。采用一种网状结构的静电传感器测量气力输送管道弯管处的颗粒速度与浓度分布。为了研究传感器的特性,首先建立了网状静电传感器的有限元模型。根据有限元仿真结果,优化网状静电传感器的设计,使其拥有更高更均匀的灵敏度分布,在实验室规模颗粒流实验平台上进行了实验研究。通过对上下游平面对应位置网状电极所得静电信号进行互相关运算,可以估测颗粒的轴向速度分布;通过对同一平面网状电极静电信号的均方根值进行重建,可以得到固体颗粒的相对浓度分布。实验研究表明,该网状静电传感器可以用来测量气力输送管道弯管处颗粒速度与浓度分布。     

斜面透镜光纤在反射式光纤位移传感器中的应用（英文）

介绍了一种斜面透镜光纤在反射式光纤位移传感器中的应用,即接收光纤采用斜面透镜光纤。基于平面式单光纤对光强调制特性函数表达式,建立了斜面接收光纤单光纤对光强调制特性的数学模型,通过对调制特性函数的仿真实验,得出了光纤间距、光纤芯径和光纤数值孔径等参量对传感器调制特性的影响规律。     

The double electrostatic ion ring experiment: a unique cryogenic electrostatic storage ring for merged ion-beams studies

We describe the design of a novel type of storage device currently under construction at Stockholm University, Sweden, using purely electrostatic focussing and deflection elements, in which ion beams of opposite charges are confined under extreme high vacuum cryogenic conditions in separate "rings" and merged over a common straight section. The construction of this double electrostatic ion ring experiment uniquely allows for studies of interactions between cations and anions at low and well-defined internal temperatures and centre-of-mass collision energies down to about 10 K and 10 meV, respectively. Position sensitive multi-hit detector systems have been extensively tested and proven to work in cryogenic environments and these will be used to measure correlations between reaction products in, for example, electron-transfer processes. The technical advantages of using purely electrostatic ion storage devices over magnetic ones are many, but the most relevant are: electrostatic elements which are more compact and easier to construct; remanent fields, hysteresis, and eddy-currents, which are of concern in magnetic devices, are no longer relevant; and electrical fields required to control the orbit of the ions are not only much easier to create and control than the corresponding magnetic fields, they also set no upper mass limit on the ions that can be stored. These technical differences are a boon to new areas of fundamental experimental research, not only in atomic and molecular physics but also in the boundaries of these fields with chemistry and biology. For examples, studies of interactions with internally cold molecular ions will be particular useful for applications in astrophysics, while studies of solvated ionic clusters will be of relevance to aeronomy and biology.     

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.     

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.     

A "tabletop" electrostatic ion storage ring: Mini-Ring

We report on the design, construction, and commissioning of a novel electrostatic ion storage ring of small dimensions--in the following referred to as "Mini-Ring." Mini-Ring consists of four horizontal parallel-plate deflectors and two conical electrostatic mirrors. Ions are injected through the two deflectors on the injection side and off axis with respect to the conical mirrors which face each other. The first injection deflector, originally at zero voltage, is switched to its set value such that the ions after one turn follow stable trajectories of lengths of roughly 30 cm. This design reduces the number of electrodes necessary to guide the ion beam through the ring in stable orbits. The six elements (deflectors and mirrors) are placed on a common grounded plate--the tabletop. Here, we present the design, ion trajectory simulations, and results of the first test experiments demonstrating the successful room-temperature operation of Mini-Ring at background pressures of 10(-6) - 10(-7) mbar.     

Design and evaluation of electrostatic sensors for the measurement of velocity of pneumatically conveyed solids

Electrostatic sensing technology in combination with correlation signal processing offers a promising solution to the on-line continuous measurement of velocity of particulate solids in pneumatic pipelines. This paper describes the fundamental mechanism of the electrostatic sensing and identifies the important aspects of the design of constituent elements of the sensor including electrodes, amplifiers and sensing heads. Experimental evaluation of a prototype commercial product called V-TESS 500 was conducted on 36 mm bore vertical and horizontal sections of a pneumatic conveyor circulating corn-flour and pulverised coal over a velocity range of 6 to 45 m/s for mass concentration of particles between 0.014 and 5.7 kg/m³. The performance of the instrument was quantified in terms of repeatability, linearity and response time. The uncertainty of the system was studied by comparing the measured solids velocity to the superficial air velocity in the pipeline. Effects of particles' accretion on the inner surface of the pipe wall on the measurement are also included. Results obtained demonstrate that the system is capable of providing solids velocity measurements with repeatability better than ±2% and response time less than 2.5 s.     

精密轴承套圈附加回火工艺改进

为了解决公司附加回火设备不足,节约电力和人力,精密套圈附加回火采用了回火工艺。试验证实,两种回火采用同一工艺对产品的硬度降低值和形状改变是可以接受的,亦是附加回火应该追求的。     

Comparative study of electrostatic sensors with circular and probe electrodes for velocity measurement of pulverised coal

This paper presents recent progress on the velocity measurement of pulverised coal in pneumatic pipelines using electrostatic sensors in combination with correlation signal processing techniques.A comparative study of electrostatic sensors with circular and probe electrodes was conducted on a 94 mm bore horizontal pipeline in a 4 MW furnace.The advantages and limitations of both sensors are discussed.Experimental results demonstrate that both sensors are capable of providing pulverised coal velocity measurement with excellent repeatability and dynamic response.     

弹性阀座加工方法的改进

对弹性阀座的机械加工工艺和冲压加工工艺进行了对比,并分析了冲压加工所产生的误差,介绍了冲压加工的特点及级进模的结构。     

Research on improvement of machining accuracy of micro-rods with electrostatic induction feeding ECM

Micro-rods were machined by electrochemical machining using the electrostatic induction feeding method, with which ultra-short current pulse duration of several tens of ns can easily be obtained. A tungsten plate and stainless steel (SUS304) rod were used as the tool electrode and workpiece, respectively. To improve the machining accuracy, the machining characteristics when the workpiece is fed in the axial and radial directions were investigated using NaCl aqueous solution as the electrolyte. When fed in the axial direction, the machinable length of the micro-rods was found to peak at the optimum feed speed because of the influence of pitting corrosion and collision between electrodes. When the workpiece was fed in the radial direction, the influence of pitting corrosion decreased, however, the micro-rod was shortened with increasing feed distance in the radial direction because of the stray current flowing through the end of the micro-rod. The simulation results of the material removal process agreed qualitatively with experimental results. Next, machining characteristics were compared between the electrolytes, NaCl and NaNO₃ aqueous solutions, by feeding the workpiece in the axial direction. It was found that the influence of pitting corrosion was eliminated with the NaNO₃ aqueous solution, and there was no machinable length limitation with suitable feed speeds. In addition, the taper angle and gap width were smaller with the NaNO₃ aqueous solution, compared with those of the NaCl aqueous solution. Stainless steel micro-rods of 100 μm in diameter with a high aspect ratio of 20 were fabricated with the NaNO₃ aqueous solution. According to the preliminary research results, the machinable minimum diameter of the micro-rods was investigated and micro-rods with an average diameter of 9 μm and length of 78 μm were machined successfully.