Concurrent measurement of temperature and soot concentration of pulverized coal flames

This paper presents a novel instrumentation system for the concurrent measurement of temperature and soot concentration of pulverized coal flames. The system operates on the two-color principle, combining CCD camera optical sensing and digital image processing techniques. The temperature and its distribution in a flame are calculated from the ratio between the grey-levels of corresponding pixels within two images captured at two carefully selected wavelengths. The soot concentration distribution of the flame is represented and estimated using the KL factor that is derived from intermediate information obtained during the temperature measurement. The system is calibrated using a tungsten lamp as a standard temperature source. The maximum relative error in the temperature measurement is 1.83%. Experimental results obtained on a 0.5 MW/sub th/ combustion test facility show that the temperature distribution of a coal-fired flame ranged from 1380 to 1700/spl deg/C, while the KL factor ranged from 0.18 to 0.33.     

Digital imaging-based three-dimensional characterization of flame front structures in a turbulent flame

This paper focuses on the application of a multicamera imaging system for three-dimensional (3-D) visualization and quantitative characterization of the flame front structures of a turbulent flame. The 2-D images of the flame front are captured simultaneously using identical monochromatic CCD cameras from three different directions around the flame. Dedicated computing algorithms have been developed to reconstruct the 3-D structures of the flame front using various image processing techniques such as edge detection, contour extraction, and mesh generation. A set of flame parameters, including ignition points, ignition volume, ignition surface area, and circularity, is determined from the models generated to characterize the flame front. Results obtained under a range of combustion conditions demonstrate the capability of the system for 3-D quantitative characterization of flame front structures.