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Study On The Image Reconstruction For Electrical Capacitance Tomography And The Visualization Measurement Of The Two Phase Flow In Pneumatic Conveying

Posted on:2014-01-31Degree:DoctorType:Dissertation
Country:ChinaCandidate:Z P WangFull Text:PDF
GTID:1228330401457858Subject:Thermal Engineering
Abstract/Summary:PDF Full Text Request
Based on the measured capacitance data, electrical capacitance tomography (ECT) attempts to reconstruct the distribution of a dielectric object by an appropriate algorithm. Owing to the distinct advantages such as the high speed, non-intrusive sensing, high safety and low cost, ECT is considered as a promising visualization measurement technique.This thesis focuses mainly on the ECT image reconstructions and thevisualization parameter measurement of the two phase flow in the pneumatic conveying. Major contents are presented as follows:The basic principles, system structure and typical image reconstruction algorithms for ECT is discussed. Numerical experiments are implemented to compare numerical performances of the typical image reconstruction algorithms.The accuracy and speed of the image reconstructions play a vital role in the successful applications of ECT. One of the drawbacks that restrict the improvement of ECT measurement accuracy is lack of amount of information, which brings the ill-posed nature in the process of ECT image reconstruction. As a result, measurement ability of the complicated field in ECT visualization measurement is restricted. In this thesis, a reconstruction model that considers the ECT measurement information and the dynamic evolution information of the objects of interest is proposed, and a new objective functional is designed. Numerical simulation results indicate that the proposed algorithm has the advantages such as the low computational complex, and can overcome the numericalinstability of ECT image reconstruction. The spatial resolution of the reconstructed images is improved, and the distortions are relatively small.The flow field in the pneumatic conveying is complicated, in which accurately measuring the distribution of phases and the concentration of the solid particles are important to understand the physical mechanisms and improve the system efficiency. In the thesis, the visualization measurement study on the distributions of phases and the concentration of the solid particles is implemented. The experimental results indicate that ECT approach is feasible.A measurement approach that integrates the spatial filtering method and ECT is proposed to measure the mass flux of the solid particles in a two phase pipeline. Experimental results indicate that the proposed method is feasible, which paves a way for resolve the challenge of accurate measurement of the mass flux of the solid particles.
Keywords/Search Tags:pneumatic transport, gas-solid flow, electrical capacitance tomography, dynamic reconstruction algorithm, visualization measurement
PDF Full Text Request
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