Experiments investigation on 2D distribution of soot temperature and volume fraction by image processing of visible radiation

A simple diagnostics method was presented that uses a low-cost camera to simultaneously reconstruct 2D distributions of flame temperature and soot concentration in laminar diffusion axisymmetric flames. A Manta G-504 camera with one million effective pixels was utilized for data collection, equipped with the lens type Computar TEC-55 with one customized double-bandpass filter mounted on front of the camera. This setup was used to obtain 615 and 517 nm monochromatic radiation flame images. Firstly, the spectral response spectrums and the directional emissive powers of the measurement system were calibrated. Then, the Tikhonov regularization method was used for inversing the spectral emission source term. Secondly, neglecting the self-absorption effect, the local temperature T(l) and soot concentration fv(l) could be calculated based on the ratio method. Finally, re-considering the self-absorption effect, the iterative computational method was implemented to update the calculated temperature T(l) and soot concentration fv(l). The resulting measurements reported in this study are in good alignment with the LII method and emission spectrum method. The proposed diagnostic method was found to be capable of simultaneous reconstruction of 2D distribution of soot temperature and concentration.