Difference between swirl and conventional flame pulsations in a model fire
M.V. Sherstobitov
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
Keywords: thermal imaging camera, vortex combustion, flame radiation, FFT processing
Abstract
It is known that the formation of vortex structures in a fire negatively impacts the consequences: swirling high-temperature flows of combustion products cause greater destruction than a normal fire. Identifying such vortices is a pressing issue. For this purpose, in the big aerosol chamber of the Institute of Atmospheric Optics SB RAS, two isopropanol flame plumes were simultaneously studied by the thermal imaging method. One of them was a vortex flame obtained by blowing around a stationary container installed on the axis of an ascending swirling air flow, and the other was in a container without blowing. Using the fast Fourier transform (FFT) of the time pulsations of the thermal imaging signal, the power spectra of the pulsation frequencies were calculated. In the calculated spectra, a frequency interval was determined where a significant difference between the mentioned flames was observed. The influence of distance and the averaging effect of the size of the initial region of thermal imaging signal reception on the difference in flame spectra was analyzed.
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