@Article{DoniniCrisFach:2020:GlFlSt,
author = "Donini, Mariovane S. and Cristaldo, Cesar Flaubiano da Cruz and
Fachini Filho, Fernando",
affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and
{Universidade Federal do Pampa (UNIPAMPA)} and {Instituto Nacional
de Pesquisas Espaciais (INPE)}",
title = "Buoyant Tsuji diffusion flames: global flame structure and flow
field",
journal = "Journal of Fluid Mechanics",
year = "2020",
volume = "895",
pages = "A17",
month = "July",
keywords = "laminar reacting flows, buoyancy-driven instability, vortex
dynamics.",
abstract = "The present work analyses how buoyancy is impacting the topology
of diffusion flames established around a horizontal cylindrical
burner. The flow conditions are chosen such that the system is
subjected to negative and positive buoyant forces. It is proposed
in this study to investigate the effect of a modulation of the
balance between these buoyant forces on the flame structure by
varying the temperature of the ambient atmosphere. More
specifically, conditions are sought for establishing a buoyant
Tsuji diffusion flame characterized by a very low level of strain
rate in its lower part (i.e. below the burner). To understand the
fundamental mechanisms controlling the whole flame topology, a
model is proposed which assumes steadiness and incompressibility
of the flow while retaining buoyancy effects in the momentum
balance. The results showed that an increase of the ambient
temperature leads to the appearance of a counterflow zone below
the burner where the flame is undergoing very low levels of strain
rate. The overall flame proves to be shorter than its counterpart
observed in the forced convection regime. In addition, it is shown
that an order of magnitude analysis is able to recover the
sensitivity of the flame behaviour to the Peclet and Froude
numbers as well as to the combustion parameters. In a certain
range of the ambient-atmosphere temperature, the flow field
changes dramatically: for the same boundary conditions, there are
two steady-state solutions which depend on the initial conditions,
i.e. the system presents a hysteresis.",
doi = "10.1017/jfm.2020.266",
url = "http://dx.doi.org/10.1017/jfm.2020.266",
issn = "0022-1120",
language = "en",
targetfile = "donini_buoyant.pdf",
urlaccessdate = "01 jun. 2024"
}