Insights into the flame transitions and flame stabilization mechanisms in a freely falling burning droplet encountering a co-flow

Vadlamudi, G and Aravind, A and Basu, S (2023) Insights into the flame transitions and flame stabilization mechanisms in a freely falling burning droplet encountering a co-flow. In: Journal of Fluid Mechanics, 977 .

PDF jou_flu_mec_997_20233.pdf - Published Version Restricted to Registered users only Download (2MB) | Request a copy

Abstract

The present study investigates the flame dynamics of a contactless burning fuel droplet under free fall subjected to a co-flow. The dynamic external relative flow established due to co-flow and droplet acceleration results in a series of droplet flame transitions. Different flame structures were observed, including a wake flame, reversed wake flame and enveloped flame. Following ignition, the droplet is allowed to fall through the central tube of a co-flow arrangement, and, at its exit, the droplet flame encounters the co-flow. The wake flame, which was established based on the droplet's instantaneous velocity of descent, encounters the abrupt relative velocity jump due to the co-flow. This causes the droplet flame to go through various transitions as it approaches equilibrium with the surrounding flow. Once it equilibrates, the droplet flame evolves in response to the instantaneous relative flow velocity. The droplet flame evolves by altering both its shape and the stabilization mechanism. Two stabilization mechanisms were identified for the droplet wake flame: edge-flame stabilization and bluff-body stabilization. The stabilization mechanism for different flame structures and the transition events have been theoretically analysed, and the relation between flame shape evolution and flow velocity has been determined based on the flow-field characteristics at the corresponding Re (Reynolds number) range. Furthermore, these correlations are employed in a mathematical formulation based on the spring-mass analogy, which predicts the droplet flame evolution after encountering the co-flow, including all the transition events. © The Author(s), 2023.

Item Type:	Journal Article
Publication:	Journal of Fluid Mechanics
Publisher:	Cambridge University Press
Additional Information:	The copyright for this article belongs to Cambridge University Press.
Keywords:	Drops; Flow velocity; Reynolds number; Stabilization; Wakes, Co-flow; Contact less; Droplet flames; Flame dynamics; Flame stabilization; Flame structure; Flame transition; Reacting multiphase flow; Relative flow; Stabilization mechanisms, Combustion, burning; combustion; fire; fuel; multiphase flow; stabilization
Department/Centre:	Division of Mechanical Sciences > Mechanical Engineering
Date Deposited:	01 Mar 2024 09:52
Last Modified:	01 Mar 2024 09:52
URI:	https://eprints.iisc.ac.in/id/eprint/84012

Actions (login required)

View Item