Abstract
A multi-spectral imaging system is proposed to reconstruct the soot temperature and volume fraction fields of a laboratory-scale ethylene flame. The Charge-coupled device (CCD) cameras with Liquid Crystal Tunable Filters (LCTF) were applied to capture the multispectral flame images for obtaining monochromatic radiative intensities. The LCTFs provide images of the flame at multiple wavelengths and generate high-resolution spectra at every pixel. A least square QR decomposition (LSQR) method is applied to solve the large ill-posed equations and obtain the multi-wavelength local emission distributions from which temperature and volume fraction profiles can be extracted. Before conducting the experimental measurement, the calibration method of the multi-spectral imaging system is introduced, and the calibration results with 6 different wavelengths are demonstrated. The measured region of the flame is divided into 7×7×3 volume elements, and specifically it is dispersed to 3 layers in the vertical direction. Considering the measured distribution profiles, the experimental reconstruction results are determined to be reasonable.
