基于转移和感应电荷信号分解与融合的气固两相流测量机理研究

The electrostatic method for gas-solid two-phase flow which has the advantages of simple structure & high sensitivity, integrating with industrial process automation, has a positive significance in increasing efficiency and saving energy. Aiming at the most widely used electrostatic sensors with flush-mounted electrodes, where the measured signal contains both transferred and induced charges, the coupled signals will be separated by a signal decomposition method. Combining spatio-temporal data of induced signal with the relationship among transferred information, particle flow behavior, and charge status, two research approaches can be verified and merged with each other. Finally the electrostatic method for gas-solid two-phase flow integrating “contact charge transfer” and “electrostatic induction” will be proposed. The highlights are as follows: firstly, based on the time-frequency domain characteristics, the signal decomposition method will be proposed for separating transferred and induced charge signals, then the information can be extracted and fused. Secondly, based on the cross-correlation sensitivity matrix and spatial sensitivity matrix, the particle velocity and concentration distributions will be reconstructed by the spatio-temporal data coupled with induced charge signal. Finally, combining macroscopic flow field with microscopic electron transfer model, the relationship between transferred information and particle flow behavior, and charge status will be obtained.

静电法气固两相流测量具有结构简单、灵敏度高等特点，与工业过程自动控制相结合，对于提高效率、降低能耗具有十分积极的意义。本申请针对应用最广泛的内壁嵌装电极式传感器采集的信号包含转移电荷和感应电荷信息的特点，提出适用的信号分解方法。结合感应电荷信号时空数据处理方法和转移电荷信息与颗粒流动、荷电状态的关系，从融合角度实现两条研究途径的相互印证和归并，建立综合“接触电荷转移”与“静电感应”的静电法气固两相流测量方法。其创新在于：(1)依据信号时频域特征，提出分解方法，将转移与感应电荷信号有效分解，再进行信息提取和融合；(2)以互相关灵敏度矩阵和空间灵敏度矩阵为基础，借助感应电荷时空耦合数据重建颗粒速度和浓度分布；(3)将流场的宏观分布信息与微观的电子迁移过程相结合，获得转移电荷信息与颗粒流动、荷电状态的关系。

在气固两相流测量中，内壁嵌装式静电传感器由于结构简单，且耐磨和耐压性能良好，是目前工业现场应用最广泛的静电法传感器形式。本项目针对内壁嵌装式静电传感器采集的转移电荷和感应电荷信号的时频域特点，分别提出了基于离散小波变换的频域信号分解法和时域波形特征的时域信号分解法。为了分析流场宏观流动特性与荷电颗粒分布和速度分布的关系，建立了一套基于CFD-DEM和COMSOL的耦合仿真平台，来实现对气固两相流场与静电场的耦合仿真。针对静电层析成像系统中独立测量信息数较少，空间灵敏场分布不均匀及测量信号信噪比较低的问题，构建了一套双截面32电极的静电层析成像系统和提出了一种结合感应电荷信号时空数据和互相关灵敏度矩阵的直接速度分布测量方法。针对不均匀的电荷分布给速度分布重构带来较大误差的问题，提出了一种基于电荷分布的直接速度分布测量方法，有效地增强了对不同位置颗粒速度的感知能力。分析了“接触电荷转移”或“静电感应”气固两相流测量的优缺点，依据转移电流信号时域特征（颗粒径向运动）的敏感性和感应电流信号频域特征（颗粒轴向运动）的宏观稳定性而定义了新的信号特征值，进而提出了一种综合运用转移和感应信号的气固两相流颗粒质量流量表征模型，与单独的信号源模型相比，其具有更高的精度和稳定性。