Abstract: Electrical capacitance tomography (ECT) is a technique for two-phase flow measurement. The image reconstruction of ECT is a nonlinear and ill-posed inverse problem. The sensitivity distribution of ECT is inhomogeneous and only few measurements can be obtained, which causes the low quality of reconstructed images for the objects in the center. More measurements can be obtained by increasing the number of electrodes. But it will cause the decrease of measurement values and lower measurement accuracy. Under the condition of ensuring the measurement accuracy,the 24 combined-electrode sensor for ECT was proposed and two exciting-measuring modes were studied. The values and the dynamic range of measured capacitance values, the uniformity of sensitivity distribution and the reconstructed images of different flow regimes were compared with the conventional 12-electrode sensor. Simulation results showed that the sensitivity distribution was more uniform and the reconstructed images for the objects in the central locations were improved obviously by using 24 combined-electrode ECT sensor.

Key words: electrical capacitance tomography, image reconstruction, combined-electrode, exciting-measuring mode

摘要： 电容层析成像图像重建为非线性不适定反问题，其敏感场分布不均匀，可获得的测量数据有限，中心处物体的成像效果不佳。增加电极数目，可获得更多的电容测量数据，减小其不定性，同时改善敏感场分布。但同时导致电容测量值变小，测量精度下降。在保证电容测量精度的前提下，提出了24电极组合式电容层析成像传感器结构，研究了两种激励测量方案，并与传统12电极电容层析成像传感器进行了对比分析，包括电容测量值的大小及其动态测量范围、灵敏场分布的均匀性以及不同流型下的重建图像。仿真结果表明,与12电极电容层析成像传感器相比，采用24电极组合式电容层析成像传感器，其电容测量值大，可较好地保证测量精度，其灵敏度分布更加均匀，对中心处物体的成像质量明显提高。

关键词: 电容层析成像, 图像重建, 组合电极, 激励测量模式