Research On The Array Electrostatic Sensor Imaging System

The Gas-solid two-phase flow widely exists in scientific research and the process of industrial production. The measurement of the flow pattern is important for the theoretical study of two-phase flow and also favors the safety and efficiency of productive process. It has been a hotspot in current researches. The electrostatic measuring method is a novel inspection instrument, the detection of two-phase flow parameters is realized by the elec-trostatic characteristics of solid particles. This method has the advantages of being simple in structure, fast in response and low in cost. In this paper, the flow pattern was real-time visualized by using the array electrostatic sensor imaging system. The relevant theory and experiment device was studied in the paper.In the paper, the research status of electrostatic sensor and image reconstruction used in detection of two-phase flow parameters was analyzed. The basic principle of electro-static measuring method was studied. Based on these theory, the new structure of an array electrostatic sensor was proposed. The finite element model of the system was established by the COMSOL Multiphysics software. The non-uniformity of the sensing space of the sensor is verified. The distribution curves of the sensor sensitivity in axial, radial and circumferential directions were obtained. The structure of sensor and electrode size pa-rameter were optimized on the base of sensitivity distribution characteristic.The electrostatic tomography algorithm was analyzed according to the characteristic of the sensor. Firstly, modeling of forward problem and division of imaging area were fin-ished by the finite element model. Tikhonov regularization was used to solve the inverse problem. The edge error was corrected by using the method of boundary filtering and the image was sharpened by the Laplace operator. Based on the maximum entropy method, the binaryzation processing of the image was setup. These make higher accuracy and identifiable degree of the reconstructed imagesA gas-solid two-phase flow simulation experiment was established to test the system. The signal conditioning circuits and the control program were designed. The control pro-gram and the imaging program were designed. According to the simulation experiments, the new array electrostatic sensor has better performance than the traditional structure sensors. The experimental results of different flow pattern were compared and accurate imaging results were obtained.