The anchoring mechanism of a bluff-body stabilized laminar premixed flame

Kedia, Kushal S.; Ghoniem, Ahmed F.

The anchoring mechanism of a bluff-body stabilized laminar premixed flame

Type

Article

Authors

Kedia, Kushal S.

Ghoniem, Ahmed F.

KAUST Grant Number

KUS-11-010-01

Date

2014-09

Abstract

The objective of this work is to investigate the mechanism of the laminar premixed flame anchoring near a heat-conducting bluff-body. We use unsteady, fully resolved, two-dimensional simulations with detailed chemical kinetics and species transport for methane-air combustion. No artificial flame anchoring boundary conditions were imposed. Simulations show a shear-layer stabilized flame just downstream of the bluff-body, with a recirculation zone formed by the products of combustion. A steel bluff-body resulted in a slightly larger recirculation zone than a ceramic bluff-body; the size of which grew as the equivalence ratio was decreased. A significant departure from the conventional two-zone flame-structure is shown in the anchoring region. In this region, the reaction zone is associated with a large negative energy convection (directed from products to reactants) resulting in a negative flame-displacement speed. It is shown that the premixed flame anchors at an immediate downstream location near the bluff-body where favorable ignition conditions are established; a region associated with (1) a sufficiently high temperature impacted by the conjugate heat exchange between the heat-conducting bluff-body and the hot reacting flow and (2) a locally maximum stoichiometry characterized by the preferential diffusion effects. © 2014 The Combustion Institute.

Citation

Kedia KS, Ghoniem AF (2014) The anchoring mechanism of a bluff-body stabilized laminar premixed flame. Combustion and Flame 161: 2327–2339. Available: http://dx.doi.org/10.1016/j.combustflame.2014.02.005.

Acknowledgements

This work was supported by King Abdullah University of Science and Technology (KAUST) award number KUS-11-010-01. We would like to acknowledge Dr. Habib Najm, Dr. Cosmin Safta and Dr. Jaideep Ray (Combustion Research Facility, Sandia National Laboratories, Livermore, CA, USA) for their major contribution towards the SAMR tool development.