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COBEM 2021
26th International Congress of Mechanical Engineering
STUDY OF FLAME ACCELERATION IN CLOSED AND HALF-OPEN DUCTS
Submission Author:
Rafael Quines , RS
Co-Authors:
Rafael Quines, Manuel Nzinga, Andrés Armando Mendiburu Zevallos
Presenter: Rafael Quines
doi://10.26678/ABCM.COBEM2021.COB2021-0283
Abstract
The objective of the present study is to validate the available theory of early-stage flame acceleration in closed and half-open ducts. To achieve this goal, first, a review of the flame propagation inside ducts was presented. Afterward, several results from published works related to flame acceleration in ducts were collected and analyzed. The study of flame propagation inside ducts is relevant to the safety of industrial facilities. The flame propagation can be classified into deflagrations and detonations. The deflagrations occur at a subsonic speed (M<1), while detonations occur at supersonic speed (M>1). The present work is focused on deflagrations. The flame acceleration develops with a finger shape flame front, growing exponentially over time. The mechanism of the flame front inversion will be discussed and outlined. Thus, parameters as the equivalence ratio and the type of fuel will be considered for analysis. The theory for the initial stages of flame acceleration for low Mach numbers, proposed by Valiev, was validated with experimental data published in recent works. The results show that the available theory is accurate for the determination of the maximum flame speed by using experimental data of flame tip position at the time at which the flame skirt touches the sidewalls. A relevant parameter in flame propagation is the maximum calculated flame tip velocity ratio to the experimental value. A good correlation was obtained between this parameter, the laminar flame velocity, and the time at which the flame skirt touches the sidewalls.
Keywords
flame propagation, closed ducts, premixed flames, flame front inversion
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