Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
NUMERICAL STUDY OF THE BUOYANT DIFFUSION FLAMES STABILITY IN A RECTANGULAR GROOVE
Submission Author:
Jean Carlos Guedes Souza , ES
Co-Authors:
Renan Batista Matheus Ferreira, Jean Carlos Guedes Souza, Fernando Filho Fachini, Caio Maioli, Guilherme Alvarez, Eduardo Reis Sampaio Filho, Leandro M. Fernandes
Presenter: Guilherme Alvarez
doi://10.26678/ABCM.COBEM2023.COB2023-1014
Abstract
The objective of this work is to study numerically the transient behavior of buoyant diffusion flames in a rectangular groove, in which the fuel is methane. The simulations are performed by the fireFOAM solver, included in OpenFOAM, because it describes very well reacting flow driven by buoyancy. The instability of buoyant diffusion flames is a classic problem arising from the formation of vortices at the base of the flame. These vortices are generated by the difference in velocities in the shear layer at the base of the flame. The natural flow, typical of combustion with very low velocity, increases the intensity of the vortices and displaces them towards to the tip of the flame. During the at work displacement, the vortices augment their radii. Depending on the height of the flame, the effect of the vortices can be flickering or puffing. Flickering is the oscillatory movement of the flame tip caused by the passage of vortices and puffing is the flame squeezing which leads to a local extinction and a pocket flame is separated from the main flame and transported away. Most of the studies already carried out in this issue involve flames with axisymmetric geometry. At the present analysis, the flame geometry is imposed by a rectangular groove. No pyrolysis and soot chemistry were considered. In this work, the infinite-fast chemistry combustion model is assumed. The groove geometry allows a two-dimensional analysis and symmetric condition is imposed to reduce even more the computational cost. The Reynolds number, based on the groove width and fuel velocity or the air flow imposed by the buoyancy, shows that the flow is in the laminar regime. The simulation results capture the physics of the phenomenon in question: the shape of the flame, the oscillation frequency, and the vortices dynamics. Also the structure of the flow field and the temperature field are obtained.
Keywords
Groove, Flickering, Buoyant Diffusion Flames
