金属颗粒的电容式速度测量方法研究

Research on the capacitive velocity measurement method of metal particles

针对金属材料在静电场中呈现出的特殊性,设计了一种用于检测管道中金属颗粒速度的电容式传感器。首先,基于多电极理论建立了电容传感器测量金属物质的数学模型,在此基础上,使用COMSOL Multiphysics有限元分析工具建立了传感器三维仿真模型,并对其空间灵敏度分布特性进行了分析。然后,基于该传感器的空间滤波效应对金属颗粒速度测量原理进行了理论分析,建立了传感器输出信号功率谱截止频率和金属颗粒速度之间的关系式。最后,开发了基于三角电极电容传感器和电容数字转换芯片Pcap01的金属颗粒速度测量系统,并在重力输送装置进行了验证及分析。实验结果表明,该测量方法具有良好的可行性,在2.44~5.34 m/s的速度范围内,测量速度的重复性误差小于4%。

In view of the special characteristics of metal materials in electrostatic field, a novel electrode capacitive sensor is designed to detect the flow velocity of metal particles in the pipeline. Firstly, based on the multi-electrode theory, a mathematical model for measuring metallic substance with capacitive sensor is formulated. On this basis, a 3 D simulation model of the sensor is established by utilizing the COMSOL Multiphysics finite element analysis tool. The spatial sensitivity distribution characteristics of the sensor is analyzed. Then, based on the spatial filtering effect of the sensor, the principle of metal particle velocity measurement is introduced. The relationship between the cut-off frequency of the sensor output signal power spectrum and the metal particle velocity is established. Finally, a specific measurement system based on the triangular electrode capacitance sensor and the capacitance digital conversion chip Pcap01 is further developed. Experiments are verified and analyzed on a gravity transmission device. Theoretical and experimental results show that the measurement method has good repeatability. In the range of 2.44~5.34 m/s, the repeatability error of the measurement velocity is less than 4%.