New Structure Study Of Electrical Capacitance Tomographic Sensors Used For Multiphase Flow Measurement

Electrical capacitance tomographic technology,simply called ECT technology,is a kind of imaging technology which is usually used in multiphase flow measurement.Because of the advantage of contactless real-time imaging,it develops rapidly.As a new technology,ECT technology is faced with a lot of problems.Two main problems of them are imaging equality and noise immunity.There are two method to solve the problems.One is to improve the existing algorithms output forward new algorithms,the other is to optimize the construction of ECT sensors or design sensors with new construction.The main work of this article is about how to solve the main problems of ECT technology.The background and theory of ECT technology and ECT system are detailed introduced in this article.Several classical image reconstruction algorithms are also introduced.The simulation of 2D ECT sensors which uses different sensors and different algorithms is conducted.It shows that the imaging equality will decline when the distance of electrodes increases.It also proves that increase the number of electrodes will improve the imaging equality.But the distance of electrodes has greater influence than the number of electrodes.The LBP algorithm can reconstruct image rapidly,it performs well in simple flow field but performs very badly in complex flow field.The ART algorithm performs badly in every condition of the simulation.The Tikhonov algorithm is good at distinguish details of flow field.The Landweber algorithm has a good image equality of every condition,but its speed of image reconstruction is slower than other algorithms.The simulation of 2D ECT sensors proves that the construction of ECT sensors and algorithms have big influence in image reconstruction.After the study of 2D ECT sensors,this article mainly studies the construction of ECT sensors.A new sensor which is called ?-shaped ECT sensor is designed.Simulation of it with compared sensors are conducted.It tells people that ?-shaped ECT sensor can reconstruct image stably.Through the analysis of variance and evaluation of image,?-shaped ECT sensor is proved with excellent noise immunity.The ?-shaped ECT sensor and the method of analysis of variance are the innovation points of this article.The influence of image equality by metal shield of ECT sensors is also studied in this article.When add metal shield to ECT sensors,regular distortion will appear at the position which is close to the electrode.If the ?-shaped metal shield is added to the rectangular ECT sensors,the image equality of the central flow field will improve and become more stable.The experiment is designed on the basis of simulation.The experiment proves that the metal shield can increase the image equality obviously.It verifies the existence of regular distortion,too.Combine the simulation and experiment,the metal shield can be proved to increase the image equality.