IR thermography study of flow structure and parameters in diffusion flames

The flame structure and flow modes have been investigated in the process of diffusion combustion of a number of liquid fuels, such as ethanol, benzine, kerosene and diesel fuel, by using the technique of infrared (IR) thermography in the narrow spectral range (2.5–2.7 microm). IR thermography provides useful information on the thermal behavior of turbulent diffusion flames, which is the thermal representation of turbulent processes in the hydrodynamic structure of flames. By analyzing IR images and spectra of flame temperature fluctuations, seven characteristic zones with different flow modes have been identified in the flames. To estimate flame flow parameters, the turbulent Reynolds number has been used thus taking account the amplitude and frequency of the temperature fluctuations determined by processing IR images of flames. The Reynolds number strongly increases during the diffusion combustion of kerosene, in contrast to benzine, diesel fuel and ethanol. This can be explained by a more complex chemical composition of kerosene and a multi-stage character of chemical reaction