Quantitative Imaging of Temperature and OH Concentration From Single Wavelength Planar Laser-Induced Fluorescence

Multiple species imaging from CFD fused H2O absorption spectral tomography and transfer learning

“…Fifteen different heights above the velocity inlets were selected at 5 mm intervals between 5 mm and 75 mm for each of the five cases to create 75 groups of reference images with 100 × 100 pixels. A pentagonal fan-beam layout derived from a real LAS tomographic sensor [20] was used to calculate projection values of normalized second harmonics and OH mole fractions. This layout contained 21 projections at each angle, so 105 projections were obtained from one reference image group.…”

“…Absorption spectrum of H 2 O at 7185.6 cm −1 and 7444.4 cm −1 In network fine-tuning, the normalized second harmonics projection values obtained from the LAS sensor in the experiment were used to form input vectors. Images of the OH mole fraction distributions were calculated from fluorescence images of OH and reconstructed temperature images [20]. Their spatial resolution was 1000 × 1000 pixels, much higher than that of reconstructed images from LAS tomography.…”

“…Besides the choice of more lasers for different absorption lines, planar laser-induced fluorescence (PLIF) is introduced in LAS tomography, and enables the concentration imaging of one extra species except for the target molecular species of LAS [20]. Higher spatial resolution can be achieved by the PLIF-fused LAS method, but concentration imaging of two or more extra species are still not available.…”