Coupling of Fluid Field and Electrostatic Field for Electrical Capacitance Tomography

Abstract

The performance of an electrical capacitance tomography (ECT) sensor is usually evaluated by static experiment with solid material(s) for some typical distributions encountered in two-phase flows. Considering the soft-field effect of an ECT sensor, the existing evaluation method is not appropriate for evaluating the performance of ECT for the real complex two-phase flows. In this paper, a new simulation model is proposed by coupling two physical fields: fluid field and electrostatic field, based on a mixture model and an electrostatic model. The mixture model is based on the diffusive flux model, which is suitable for liquid–solid mixtures with high concentration of solid particles. An ECT sensor with 12 electrodes is modeled based on an electrostatic model with a periodic excitation signal. The two models are coupled by an additional electric force in the momentum conservation equation in the mixture model. The time-varying permittivity distributions and capacitance data are obtained from the computational simulation based on the coupling model to investigate the performance of the ECT sensor and image reconstruction. Linear backprojection and Landweber iteration with different parameters are used to reconstruct images. Experiment was carried out using a rotation device with a 12-electrode ECT sensor to validate the simulation results. Both simulation and experimental results verify that the proposed coupling model is valid for evaluating the performance of ECT sensors and image reconstruction algorithms.