阵列式静电-电容传感器灵敏度特性研究

结合静电和电容传感技术各自的特点,提出了阵列式静电-电容传感器用于气固两相流中固相颗粒的局部速度、局部浓度以及局部流量测量。利用静电极片阵列与电容极片阵列获取管道内颗粒的速度分布与浓度分布,进而计算出颗粒的局部流量。该阵列式传感器参数测量的准确性直接取决于它的空间灵敏度分布特性。对静电极片阵列和电容极片阵列的灵敏度特性进行了研究。首先,建立了静电极片阵列的三维静电场模型,通过有限元法分析静电极片阵列的结构参数(电极长度、电极覆盖角等)对传感器灵敏度特性的影响;然后根据电磁场理论建立电容极片阵列的数学模型,并对其进行数值计算,研究管道厚度、管道介电常数、电极覆盖角等参数对传感器灵敏度特性的影响;最后搭建了传动带装置进行了实验研究,实验结果证实了模拟结果的准确性,为阵列式静电-电容传感器的优化设计提供理论依据。

Spatial sensitivity of electrostatic-capacitance sensor array

An electrostatic capacitance sensor array is proposed to measure the local velocity, local volumetric concentration and local mass flowrate of particles in gas solid two phase flow system, combining the electrostatic and capacitive sensing technology. The velocity distribution and the concentration distribution of particles over the cross section of the pipeline can be measured by the electrostatic electrode array and capacitance electrode array, respectively. Thus, the local mass flowrate can be calculated. The accuracy of the solid flow measurement directly depends on the sensitivity distribution of the electrostatic capacitance sensor array. In this paper, the spatial sensitivities of the electrostatic electrode array and the capacitance electrode array are investigated numerically and experimentally. Firstly, in terms of the electrostatic electrode array, a 3 D electrostatic field model of electrostatic electrode array is established, and the effect of the parameters of electrostatic sensor array (length of electrode and electrode coverage, etc.) on its sensitivity is analyzed through the finite element analysis. Then, the mathematical model of capacitance electrode array is built based on electromagnetic field theory. Simulations are carried out and the influence of the thickness of pipe, pipeline permittivity and the electrode coverage of capacitance array on its sensitivity are further discussed. Finally, experiments were performed on a belt conveyor to validate the simulations. The numerical and experimental results consistency is proved by the numerical and experimental results. The work presents the theoretical basis for optimal design of the electrostatic capacitance sensor.