Optical Diagnostics of Hydrogen-Air Diffusion Jet Flame

The aim of this work is to adapt the methods of optical Hilbert diagnostics for visualization and study of phase optical density fields and flame temperature fields during combustion of H₂/N₂ in the air. The diagnostic complex is implemented on the basis of the IAB-451 Toepler shadow device with modified optical filtering, information source, and processing units. Visualization of phase perturbations induced by the studied medium in a probing multiwave light field is performed via polychromatic Hilbert and Foucault–Hilbert transformations in combination with registration and RGB-per-pixel processing of the dynamic structure of the images. The dynamic phase structure of the diffusion flame is visualized. From solution to the inverse problem of Hilbert optics, the temperature field of the flame is reconstructed and the value of the relative molar concentrations of the components of the fuel combustion products is restored. The reliability of the results is confirmed via comparison of hilbertograms obtained in the experiment and those reconstructed from the phase structures via the Abel transform.