The Development And Application Of 3D FE Analysis Software On ECT System

Electrical Capacitance Tomography (ECT) is a kind of Process Tomography (PT) based on capacitance sensor. ECT has the advantage of being non-intrusive, fast in response, simple in structure and low in cost. The electrostatic field inside an ECT sensor has complicated boundary shape and boundary condition; the distribution of medium is complicated, too. This kind of question has no analytical solution. So the Finite Element (FE) simulation is important to the research of ECT. The existing commercial FE simulating software is general-service, and their computing precision has been verified for a long time, but usually they are expensive and not easy to grasp. Furthermore, the commercially available packages are not flexible enough for ECT investigation. Some functions necessary to ECT investigation, for example, the calculation of field sensitivity, are shortage. Therefore, developing special FE simulating software for ECT system is necessary.In this paper, the composition, the working principle and the mathematical model of Electrical Capacitance Tomography System are described. All kinds of solution method of the electrostatic field are compared, and the Finite Element Method (FEM) is educed. Then the main function of the FE simulating software package designed by writer is introduced in detail when the main steps of FEM are discussed.The software package is developed in MATLAB under the environment of Windows 98. It is special 3D FE analyzing software for ECT, including three functions: pretreatment, FE analyzing and after-treatment. A FE-mesh generator is programmed using Matlab. The FE-mesh can be generated by this mesh generator or downloaded from the well-known commercial FE package called ANSYS. The fast calculation method of field sensitivity is improved in this paper; as a result, the computation time is reduced greatly while the correctness and accuracy of results are kept, in-depth study on ECT becomes more achievable. In after-treatment, flexible 3D cutting function is presented and various view fashions are designed to show voltage, capacitance, electrical energy intensity and field sensitivity. The friendly interface is programmed to convenience the users.The correctness and accuracy of results calculated by our software package has been tested against some analytical results and against ANSYS when the same FE mesh was used. Test results verified the high dependability and precision of our software package. Various 3D analysis of ECT sensors made by our software package is given in this paper. Some of analysis results are compared with the experiment data.