Computational fluid dynamics modeling of methane flame interaction with simulated rock rubble

ABSTRACT

Many researchers modeling fluid flow and methane gas transport through a longwall-coal-mine gob model the gob as a Darcy-type porous media. However, when studying methane gas explosions near the gob fringe, the Darcy flow assumption may not be applicable to describe flame interaction with the gob. Computational fluid dynamic studies were performed modeling methane flame propagation across a simulated gob, modeled as a Darcy porous medium and as discrete objects with varying circularity. Modeling the gob as a Darcy porous medium results in unrealistic flame propagation and does not allow for ignition within and subsequent flame propagation through the porous medium. Modeling the gob discretely (circles, hexagons, and squares) produces different levels of turbulence, impacting flame velocity, resulting in more realistic flame dynamics agreeing with experiments. This research demonstrates modeling methane gas explosions near the gob requires discrete modeling of obstacles to capture the coupling of fluid dynamics and combustion.

RÉSUMÉ

De nombreux chercheurs modélisent le flux fluide et le transport de méthane gazeux à travers un remblai de mine de charbon à longue paroi comme un milieu poreux de type Darcy. Toutefois, lors de l’étude des explosions de méthane près de la bordure du remblai, l’hypothèse du débit de Darcy peut ne pas être applicable pour décrire l’interaction de la flamme avec le remblai. Des études computationnelles dynamiques des fluides ont été réalisées en modélisant la propagation des flammes de méthane à travers un remblai simulé, modélisé comme un milieu poreux de Darcy et comme des objets discrets avec une circularité variable. La modélisation du remblai comme milieu poreux de Darcy entraîne une propagation de flamme irréaliste et ne permet pas l’inflammation à l’intérieur et la propagation subséquente de la flamme à travers le milieu poreux. La modélisation discrète du remblai (cercles, hexagones et carrés) produit différents niveaux de turbulence, ayant un impact sur la vitesse de la flamme, ce qui donne une dynamique de flamme plus réaliste, en accord avec les expériences. Cette recherche démontre que la modélisation des explosions de méthane près du remblai nécessite une modélisation discrète des obstacles pour capturer le couplage de la dynamique des fluides et de la combustion.

KEYWORDS:

• Computational fluid dynamics
• Flame propagation
• Longwall coal mining
• Methane combustion

MOTS CLÉS:

• combustion de méthane, dynamique computationnelle des fluides, extraction de charbon à longue paroi, propagation de flamme

Acknowledgments

The work described in this paper was made possible with the support of the National Institute for Occupational Safety and Health (NIOSH) Contract # 211-2014-60050. This research was performed using the supercomputer Mio at the Colorado School of Mines.

An earlier draft of this article was published in the Proceedings of the 17th North American Mine Ventilation Symposium (NAMVS 2019) prior to undergoing the CIM Journal peer-review process.

Additional information

Funding

This work was supported by the National Institute for Occupational Safety and Health (NIOSH) Office of Mine Safety and Health Research [211-2014-60050].

Notes on contributors

C. Strebinger

Dr. C. Strebinger is an Instructor in the Mechanical Engineering Department in the College of Science and Engineering at Seattle University and completed her Ph.D. in Mechanical Engineering from the Colorado School of Mines.

G. E. Bogin

Dr. G. E. Bogin, Jr. is an Associate Professor of Mechanical Engineering at the Colorado School of Mines and holds a joint appointment as a researcher at the National Renewable Energy Laboratory. [email protected]

J. F. Brune

Dr. J. F. Brune (PE) has worked in the mining industry since 1983 and is currently a Professor of Practice in Mining Engineering at the Colorado School of Mines and a Distinguished and Registered member of the Society of Mining, Metallurgy and Exploration.