Recovery of the Temperature Field in the Case of Combustion of Premixed Propane-Air Mixtures by Methods of the Hilbert Optics

Jet combustion of premixed propane-air mixtures is frequently encountered in various devices. In the present study, the flame is investigated by methods of the Hilbert optics. The diagnostic technique adapted to studying combustion products is based on visualization of phase perturbations induced in the probing light field by the examined medium with the use of polychromatic Hilbert and Foucault-Hilbert transforms combined with pixel-by-pixel processing of the dynamic structure of the recorded images. The diagnostic setup is based on the standard IAB-463M device with modified systems of optical filtration, source, and data processing. The dynamic phase structure of the propane-air flame is visualized. The temperature at reference points of the burning jet is measured by thermocouples. On axisymmetric segments, the phase function is recovered from the Hilbert curves, and the temperature field of the flame is retrieved by using the inverse Abel transform.