New method to measure non-symmetric 3-D temperature distribution of a coal flame

Three-dimensional (3-D) temperature distribution of a flame can faithfully and comprehensively represent the state of combustion. A simple, fast, economic, and relatively accurate method of measuring non-symmetric 3-dimensional temperature distribution in a coal flame with emission tomography is developed. In this method, projection data in different directions are obtained simultaneously. This eliminates the defect of a multiangular scanning CT technique in which great errors are brought about owing to the unsteady state of the flame. A finite series-expansion method is used in reconstructing the 3-D temperature distribution. This enables the application of the special feature of smooth distribution and some other, a priori, information of flames as constraints. The results of computer simulation confirm that a finite series-expansion reconstruction algorithm is more suitable to measurement of temperature distribution in a flame using limited views. Six views are used in our experiment. The measurement results were compared with the results from a thermocouple, which shows that the method is reasonable and useful for flame measurement.