Study On Flame Temperature Filed Three-dimensional Reconstructions Based On Emission Spectral Tomography

Emission Spectral Tomography (EST) is a novel none-destructive testing technology, which is the combination of the emission spectral measurement with Optical Computed Tomography (OCT). EST shows the superiorities in testing thermophysical parameters and diagnosing plasma.It is the most important testing technology used in mechanism,metallurgy,aeronautics and astronautics. There are two problems in the application of EST.On the one hand it is difficult to obtain the data of emission intensity of multi orientations and wavelengths; on the other hand the algorithms of EST need to be applicable to limited-view and incomplete data conditions.A data acquisition system with narrow-band optical filter, broad-band beam spliter, height precision area array CCD camera and four-way image capture card was proposed in order to resolve the problem of data acquisition.We can obtain the real-time projection data of emission intensity of two-orientation and two-wavelength by this system.We could obtain the data of more orientation and wavelength if there is more powerful image card.To improve the reconstruction precision in the case of few views, detailed studies on the traditional OCT algorithms, including transform-based and iterative algorithms were accomplished. A new computed tomography reconstruction algorithm based on multipurpose optimal criterion and simulated annealing theory (Multi-criterion Simulated Annealing Reconstruction Technique, MCSART) was proposed in this paper. The result of the simulating experiment shows that the MCSART algorithm is superior to the traditional iterative algorithms such as ART and SIRT under various conditions.Focusing on the two-view tomography a new algorithm (Two-view Maximum Entropy Reconstruction Technology, TVMERT) based on maximum entropy theory and Lagrange multiplier method was studied.We can get precise reconstruction result of symmetrical field and signle apex asymmetrical field with TVMERT algorithm.A flame temperature filed three-dimensional reconstruction system based on above data acquisition and computed tomograthy algorithm was developed.The software of the system was compiled in VC++6.0. Three-dimensional temperature filed on-line reconstruction can be achieved by the system.In addition several problems were studied such as image preprocessing, temperature scale, geometry scale and display of reconstruction result in the paper.Finaly,the temperature field of a candle flame was reconstructed with the system and the result shows the feasibility of the system.