Experimental Study of a Cellular Ethanol Flame Evaporating "On the Ceiling"
R. Kh. Abdrakhmanov, B. F. Boyarshinov
Kutateladze Institute of Thermophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: диффузионное пламя, ячейки, смешанная конвекция, грибовидные структуры, PIV, массоперенос, неустойчивость Рэлея-Тейлора, diffusion flame, cells, mixed convection, mushroom-shaped structures, mass transfer, Rayleigh-Taylor instability
Abstract
This paper describes the study of evaporation and combustion of ethanol under a horizontal wall in a stratified shear gas layer in the case of the Rayleigh - Taylor instability. The data on the nature of flow are obtained with the use of particle image velocimetry (PIV), and temperature profiles are recorded by a thermocouple. It is shown that the formation of cells occurs in a narrow range of air velocity of 0.6±0.05 m/s and does not depend on the height of the obstacle (backward step or an edge is 0-7 mm in height). The flow between the wall and flame front is an alternation of mushroom-shaped structures moving from one wall to another. In the cellular flame, the flow of substance (with respect to the air flow) exceeds its level in a standard laminar boundary layer three times. The averaged transverse velocity is directed away from the wall in the boundary layer with combustion without cells, and it is reduced and directed toward the wall in the cellular flame between the wall and flame front.
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