Application Study Of Wavelet Analysis In Identifying Flow Regime Of Electrical Capacitance Tomography System

Process Tomography (PT) technique is a new technique developed rapidly in recent years, which has great developmental potential and wide industrial application prospect in solving the measurement problem of multiphase flow. Electrical Capacitance Tomography (ECT) technique is a kind of PT technique based on the sensitive principle of capacitance, and it has been the most popular research direction and the main development technique of PT, due to its many distinct advantages such as non-radiation, non-invade, high speed of response, simple structure, low cost, wide application range, better safety and so on. Wavelet analysis technique is a newly emerging science and practical tool which is developing faster and faster in recent twenty years, and in many applied domains it has shown tremendous superiority and vitality in the support of Matlab. Wavelet transform has the characteristics of analyzing signals in a time-frequency way, extracting local features of signals, and providing time-varying filtering. If wavelet analysis is used in the measurement of multiphase flow and the identification of flow regimes, it has obvious characteristics of needing fewer parameters, simple processing method, and powerful wavelet analysis tool, and it also has a characteristic of identifying flow regimes in a real-time and continuous way. The object of study in this paper is major in the ECT system of 8-electrode and the identification problem of flow regimes in oil/water two-phase flows is then studied according to establish the mathematic model of capacitance sensors on the working principle. At the same time the sensitivity field is dissected on the basis of the model of wavelet finite element, and projection data is obtained to do image reconstructions for typical flow regimes based on the genetic image reconstruction algorithm. The main study content and fruit is listed as follows: 1. Firstly the working principle of ECT technique is analyzed in theory, and the mathematic model of the relative sensitivity field is established; 2. The element dissection model of quadrilateral is utilized for the sensitivity field, and the simulation analysis is done for the system; 3. Six typical flow regimes of oil-water two-phase flows are analyzed, and different eigenvalues of flow regimes are extracted; 4. The fuzzy identification method is adopted and the fuzzy identification model is established, then the fuzzy identification is done for six flow regimes; 5. The image reconstruction algorithm based on genetic algorithm is established, and image reconstructions are done for six typical flow regimes.