Insight into flickering/shedding in buoyant droplet-diffusion flame during interaction with vortex

Thirumalaikumaran, SK and Vadlamudi, G and Basu, S (2022) Insight into flickering/shedding in buoyant droplet-diffusion flame during interaction with vortex. In: Combustion and Flame, 240 .

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Abstract

The interaction of incident vortex with buoyant diffusion flame of a pendant fuel droplet (n-dodecane) is investigated in the present study. The flame stretching/shedding events occur depending on vortex strengths, which are characterized using vortex Reynolds number (Rev). Different flame response regimes have been identified for different vortex strengths. The velocity scale associated with the vortices is higher when compared to natural convection velocity leading to forward extinction, followed by flame lift-off. The flame lift-off increases with Rev, and partial extinction occurs at very high Rev. In all the cases, the flame oscillates/sheds during the vortex interaction, which causes a momentary increase in the flame heat release rate. As the vortex moves past the flame, the oscillations dampen gradually, and the flame regains the natural buoyant behavior. The high-velocity scales imposed during vortex interaction make the flow momentum-dominant, resulting in a low Richardson number (Ri). Since, the flickering frequency scaling valid for Ri>>1 is not obeyed, a new scaling has been proposed to incorporate the vortex momentum effect by using vortex circulation instead of gravity. Only a portion of the incident vortex circulation contributes to the shedding as some of it is lost to forward extinction and lift-off events. Thus, the reduced vortex velocity scale is used to estimate the critical circulation. The flame shedding height calculated using new scaling in the critical circulation equation agrees with experimental observations. © 2022 The Combustion Institute

Item Type:	Journal Article
Publication:	Combustion and Flame
Publisher:	Elsevier Inc.
Additional Information:	The copyright for this article belongs to Elsevier Inc.
Keywords:	Buoyancy; Combustion; Diffusion; Drops; Reynolds number; Velocity; Vorticity, Buoyant diffusion flames; Circulation; Droplet combustion; Flame lift-off; Scalings; Velocity scale; Vortex circulation; Vortex flame interaction; Vortex interactions; Vortex strength, Vortex flow
Department/Centre:	Division of Mechanical Sciences > Mechanical Engineering
Date Deposited:	17 Feb 2022 06:36
Last Modified:	17 Feb 2022 06:36
URI:	http://eprints.iisc.ac.in/id/eprint/71301

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