ERT/ECT技术电学特性与激励频率研究

电学层析成像技术包括ERT、ECT和EMT,但其对应系统的适用被测对象不同。为使电学层析成像技术更好地适用于多相流测量问题,采用数值仿真的方法,研究了多相流介质的电导率和介电常数对电学敏感场分布的影响,并且比较了不同电学特性参数介质场的频率特性。结果表明,电学层析成像系统的类型和激励频率可根据被测对象的电学特性参数决定。电导率较大(10~(-3)S/m)时采用电阻抗实部成像,选用ERT系统;电导率极低(10~(-5)S/m)且介质间介电常数相差较大时采用电阻抗虚部成像,选用ECT系统;且系统激励频率可选范围随电导率的增加而增大。最后将仿真结果与4种不同电导率被测场的实际测量数据进行对比验证,验证了仿真结果的正确性。

A Study ofSElectrical Properties and Excitation Frequency in ERT/ECT

TheSelectricalStomography consists of ERT, ECT and EMT, but to which the measured objects corresponding are different. To make the electrical tomography system more suitable for the measurement of multiphaseSflow, the method of numerical simulation is proposed to study the effects of the electrical conductivity and dielectricSconstant of the multiphase flow medium on the distribution of sensitive electrical field. Furthermore, the frequency characteristics of media fields with different characteristic parameters are compared. Experiments show that the electrical tomography system and its excitation frequency can be selected according to the characteristic parameters of the measured object. ERT system with the real part of impedance for imaging should be chosen when conductivity is larger (>10-3S/m), while ECT system with the imaginary part of impedance for imaging when conductivity is smaller (<10-5S/m). And the range of excitation frequency expands with the increase of conductivity. Finally, comparing the simulation results with actual measured data of four different conductivity measured fields, we verify the accuracy of the simulation results.