一种新型电容式空隙率传感器仿真研究

该文提出了一种侵入式多环套状结构电极的电容传感器,并研究它对气液两相流空隙率测量的可行性。通过建立多环套状电容传感器装置的有限元仿真数学模型,运用ANSYS软件对电容传感器有限元模型进行了二维静电场仿真。其分析了极板间的电位分布,计算不同相分布下传感器的电容及变化量,分析空隙率的设定值与仿真值对比结果,并以层流和环流为例比较并分析传感器的灵敏度以及受流型的影响。仿真结果表明,多环套状电极结构电容传感器可运用于两相流的空隙率测量技术上,为多环套状电极结构电容传感器的设计提供了部分理论依据。     

基于ECT/EST双模信息融合的磨粒图像重建算法

电容层析成像(ECT)技术因其非侵入、无辐射、可视化、响应快、成本低等优势在两相流测量中获得了广泛应用,但在发动机油路中,因摩擦产生的能量释放使磨粒荷电,对ECT传感器电容值的测量产生扰动,严重影响成像质量。为提高荷电颗粒存在情况下电容层析成像的图像重建质量,提出电容层析成像(ECT)与静电层析成像(EST)双模信息融合成像方法。该方法通过测量荷电颗粒在传感器矩形电极上感应的电荷值,得到荷电磨粒的信息;通过ECT系统得到一组电容值,并利用加权融合的修正方法,对ECT中畸变的电容值进行修正;用修正后的电容值进行图像重建。仿真实验证明:该方法能够弥补单一ECT模态的成像质量不高的不足,减弱荷电颗粒对ECT电容值测量的干扰,明显提高了图像重建质量,降低了成像误差;采用双模态重建图像方法可正确识别环状流、泡状流、核心流等几种典型流型。     

电容法多相流检测中相浓度的求解

从对电容传感器的有限元（FEM）分析及仿真入手,提出了求解油、水、气三相流相浓度的插值计算方法,并实现了三相流的定量测量。该方法所需测量参数少,便于实时、在线、连续和非侵入地检测石油多相流中各组分的含量。     

封闭管道内散装固体物料流截面相浓度测量方法研究

为了解决圆形封闭管道内散装固体物料流截面相浓度的实时测量问题，提出了一种新型有源栅极式截面相浓度检测方法，它可以有效地减少“位置效应”和“空间滤波效应”给测量精度和实时性带来的影响。设计研制了环形栅极式电容传感器及其变送电路。有限元数值分析及模拟各种流型的试验研究表明：采用这种栅极探头可使检测截面的电容灵敏度变分参数SVP显著减少，流型变化对测量精度的影响较小。该方法是一种较理想的圆形封闭管道内气固两相流相浓度检测方法。     

基于SVM及电容层析成像的两相流流型识别

两相流测量中,流型的准确识别是流动参数准确测量的基础.电容层析成像(ECT)技术是自20世纪80年代发展起来的新型检测技术,可用于两相流/多相流流型识别及固相浓度测量.支持向量机是一种基于统计学习理论的机器学习算法,即使在小样本情况下也能得到很好的分类效果.应用ECT系统测量的包含流型信息的电容测量数据,采用支持向量机算法进行流型识别,对4种典型空气-油两相流流型识别分别进行了仿真和静态实验.结果表明,该方法辨识速度快,可准确地识别典型的流型.     

一种新型的电容式油气两相流相份额传感器

本文介绍了一个高精度的电容式两相流相份额传感器。该传感器是非插入式,传感部件与测量电路集成一体,排除了寄生电容和杂散电容的影响,使测量精度和稳定性大大提高;输出是直流电压信号,便于计算机自动采集数据;动态反应快,适于实时在线测量。可用于管内油气两相流相份额测量、流型识别、两相流量测量和流动状态监测     

小管径管道气液两相流空隙率电容传感器设计

为了测量微小管道(内径5 mm)中气液两相流的空隙率,设计了具有螺旋结构电极的电容传感器。对螺旋电极电容传感器的螺距和电极宽度2个主要结构参数进行了仿真研究,结果表明当螺距在1.625~2.85倍管径、电极宽度在0.200~0.280倍螺距之间变化时,最大检测场均匀性误差小于25%,流型变化对空隙率的测量结果影响不大。静态实验结果表明,具有最优结构参数的传感器在分层流的空隙率测量中表现出了很好的线性特性。     

基于粗糙集理论两相流流型辨识方法研究

本文提出了一种基于粗糙集理论和电容层析成像系统辨识两相流流型的新方法。该法通过对极板电容测量数据进行属性分析，然后根据粗糙集理论化简属性，最后根据分类规则进行流型辨识。本流型辨识方法决策规则简单适合在线测量。仿真结果表明：此方法在两相流流型辨识中具有较高的判别精度。也为两相流流型提供了一种有效的手段。     

双层电容层析成像传感器及应用

电容层析成像在气力输送过程中具有十分重要的应用地位，可进行固相浓度分布测量，流型判断。利用双层电容层析成像传感器不仅可以进行浓度测量还可以进行相关测速。基于这种思想，设计了一种双层电容传感器，与电容测量系统结合，用于气力输送过程固相浓度和速度的测量。     

基于ECT传感器和模式识别的气液两相流空隙率测量新方法研究

基于电容层析成像(ECT)传感器和模式识别理论,提出了一种新型的气液两相流空隙率测量方法。根据流型几何特征分别建立了空隙率的三个模板库。测量时先对流型进行分类,再调用对应的模板库利用距离测度进行模板匹配,从而得到空隙率。实验结果表明该方法是可行的,有助于克服测量结果易受流型影响的问题,同时速度优于传统ECT技术方法,获得一个管截面空隙率值所花费的测量时间小于50ms,最大测量误差可小于5%,满足工业在线运行需要。     

高精度原油储罐液位计研究

通过对数字式电容液位计及等值基准电容补偿法的研究，提出将数字式电容液位计与压差法相结合，由数字式电容液位计测量原油液位和油水界面的高度，等值基准电容法补偿由于环境温度、极板腐蚀和油液粘结带来的测量误差，采用压差法测量混油密度，依据混油密度和液位高度求得油重及容积；通过高精度A/D板采集模拟和数字信号，连续对储罐内原油的液位、密度、温度等各种参数进行运算，并由智能监测仪实施全自动显示，其测量精度可达到毫米级。     

Investigation of using 60Co source and one detector for determining the flow regime and void fraction in gas–liquid two-phase flows

In this study, a simple detection system comprised of one ⁶⁰Co source and just one NaI detector was investigated in order to identify flow regime and measure void fraction in gas–liquid two phase flows. For this purpose, 3 main flow regimes of two-phase flows including stratified, homogenous and annular with void fractions in the range of 5–95% were simulated by Monte-Carlo N Particle (MCNP) code. At first step, 3 features (count under full energy peaks of 1.173 and 1.333 MeV, and count under Compton continuum) were extracted from registered gamma spectrum. These 3 extracted features were used as inputs of artificial neural network (ANNs). A primary network was trained for identifying the flow regimes, but after testing many different structures, it was found that just two regimes of stratified and annular could be completely identified from each other. After identifying the mentioned two flow regimes by the first ANN, two specific ANNs were also implemented for predicting the void fraction. Using the proposed method in this work, void fraction percentages were predicted with a mean relative error (MRE) of less than only 0.42%. Using fewer detectors is of advantage in industrial nuclear gauges, because of reducing economical expenses and also simplicity of working with these systems.     

Liquid holdup measurement in horizontal oil–water two-phase flow by using concave capacitance sensor

Due to the complex flow structures of horizontal oil–water flows, the liquid holdup measurement is still a challenging problem. In this paper, we using the finite element analysis build a two-dimensional model of the concave capacitance sensor and investigate the effect of sensor geometry on the distribution of the sensitivity field. Through calculating the sensor static response for different horizontal oil–water flow patterns, we figure out the optimum geometry of the concave capacitance sensor. In addition, we conduct experiment to obtain the measured response of the concave capacitance sensor and achieve the oil-holdup by using quick closing valve. The results indicate that the optimized concave capacitance sensor shows good performance for liquid holdup measurement of horizontal oil–water two-phase flow.     

轴承腔中润滑油气液两相分层流动研究

基于轴承腔中润滑油气液两相分层流动模型和湍流模型，采用VOF方法追踪气液界面等技术求解三维N—S公式，对腔内润滑油气液两相分层流动的特性进行了研究。分析了润滑油混合物空气体积比等结构工况参数对流体介质在轴承腔出口处压力和径向速度的影响，研究结果揭示了结构工况参数对出口压力和径向速度的不同影响趋势。将所计算得到的理论数据与国外类似结构的轴承腔工况条件和结构数据进行比较，证明了该计算方法和结果的正确性。     

Characterization of gas-liquid two phase flows using dielectric Sensors

Two phase flow regime identification and void fraction measurement is an area of considerable interest because of its wide applications in process industries. The principle involved in dielectric measurement is that the two phase flow regime is characterized by the changes in effective permittivity of the two phase fluid mixture. In the present work, a pair of parallel copper electrodes on the two sides of a glass tube acts as a dielectric sensor. As the void fraction in the glass tube changes, the effective permittivity of the medium changes. This causes a variation in the capacitance value across the electrodes. A standard IC, Oscillator 555 is employed as a tool to generate a rectangular wave. The variation in dielectric constant is analyzed based on the change in time period of the trough (T₀) of the rectangular wave that is recorded online by a data acquisition system. Experiments were performed in a 4.7 mm diameter tube with air-water, air-palmolein oil two phase fluids to study the variation in dielectric constant which is indicated as a change in time period of trough. The effect of conductivity of water on the capacitance variation is examined with water having Total dissolved solids (TDS) which is a measure of movable ions in the range 10-4000 ppm (16 µS/cm–6.3 mS/cm). The novelty in the present work is the determination of changes in capacitance value based on the change in time of trough of the rectangular wave. The technique does not require amplification or a filtering circuit, thereby leading to a precise identification of two phase flow regime.     

流体电容仪新的测量模型

本文针对油田生产测井中应用很广泛的流体电容含水率计在理论上和实验上进行了详细的研究。根据现有的实验事实，提出了高含水测量模。该模型认为，对于油水泡状流，即使在水矿化度很高时，流体电容仪仍在０－１００％的含水率范围内有油水分辨能力。     

Volume fraction measurement and flow regime recognition in dynamic gas–liquid two phase flow using gamma ray radiation technique

Gas–liquid two phase f low is probably the most important form of multiphase f lows and is found widely in industrial applications, particularly in the oil and petrochemical industry. In this study, in the first instance a gas–liquid two phase f low test loop with both vertical and horizontal test tube was designed and constructed. Different volume fractions and f low regimes were generated using this test loop. The measuring system consists of a ¹³⁷Cs single energy source which emits photons with 662 keV energy and two 1-inch NaI (Tl) scintillation detectors for recording the scattered and transmitted counts. The registered counts in the scattering detector were applied to the Multi-Layer Perceptron neural network as inputs. The output of the network was gas volume fraction which was predicted with the Mean Relative Error percentage of less than 0.9660%. Finally, the predicted volume fraction via neural network and the total count in transmission detector were chosen as inputs for another neural network with f low regime type as output. The f low regimes were identified with mean relative error percentage of less than 7.5%.