Three-Dimensional Computerized Tomographic Reconstruction of Instantaneous Distribution of Chemiluminescence of a Turbulent Premixed Flame(<Special Issue>Experimental Mechanics in Heat and Fluid Flow)

The advanced CT (computerized tomography) reconstruction technique for measuring an instantaneous three-dimensional distribution of chemiluminescence of a turbulent premixed flame is accomplished. In the technique, first, instantaneous two-dimensional images ('projection' images) of an objective flame are simultaneously taken from forty horizontal directions with a forty-lens camera. Next four hundred horizontal CT images, which are reconstructed from the 'projection' images by MLEM (maximum likelihood expectation maximization) algorithm, are vertically accumulated, resulting in an instantaneous three-dimensional distribution of flame-chemiluminescence. Results for a propane-air fuel-rich-premixed turbulent flame are as follows. The flame front is observed to be a thin wrinkled luminous region of 0.6mm in thickness. The three-dimensional result clearly shows that the cusps observed in horizontal cross-sections correspond to ridges of the three-dimensional flame front. The luminosity is quenched at the ridges by Lewis number effect. Finally, various types of display of three-dimensional distribution are performed to demonstrate the three-dimensionality of data acquisition.