Sub Topic: Fire 1 10 th U. S. National Combustion Meeting Organized by the Eastern States Section of the Combustion Institute April 23-26, 2017 College Park, Maryland Computational Study of Premixed Flame Propagation in a Gaseous-Dusty Environment with Various Dust Distributions Sinan Demir, Hayri Sezer, Torli Bush, and V’yacheslav Akkerman* Center for Alternative Fuels, Engines and Emissions (CAFEE) Center for Innovation in Gas Research and Utilization (CIGRU) Computational Fluid Dynamics and Applied Multi-Physics Center (CFD&AMP) Department of Mechanical and Aerospace Engineering, West Virginia University Morgantown, WV 26506-6106 * Corresponding Author Email: Vyacheslav.Akkerman@mail.wvu.edu Abstract: Propagation of a gaseous-dusty premixed flame front in a channel, resembling a methane-air fire scenario in a coalmine, is studied by means of the computational simulations. The core of the computational platform is a finite-volume, Navier-Stokes code solving for the reacting flow equations with a fully-compressible hydrodynamics and an Arrhenius chemical kinetics. The combustible coal dust particles are incorporated into the solver by means of the Seshadri formulation such that a real gaseous-dusty environment is replaced by an “effective fluid” with locally- modified, dust-induced flow and flame parameters. The originality of this work is in the consideration of various spatial dust concentration distributions such as the homogenous, linear, cubic and parabolic ones. Specifically, flame acceleration due to wall friction is analyzed for all these distributions; the similarity and differences in the evolutions of the flame morphology and velocity in each of these cases as well as in the case of purely gaseous combustion are identified. It is shown that a non-uniform dust distribution may result in an extra distortion or a local stabilization of the flame front, which respectively increases or reduces the total flame surface area, thereby promoting or moderating flame acceleration. Overall, the effects of non-uniform dust distribution become substantial when the channel width exceeds a certain critical value proportional to the flame thickness. Keywords: flame acceleration; gaseous-dusty combustion; computational simulation; coalmine fire safety 1. Introduction Accidental explosions of flammable gases due to the presence of the combustible dust impurities may result in injuries and deaths of personnel, as well as the destruction of expensive equipment, thereby constituting a serious demand for industries dealing with explosive materials, such as the coalmining industry that traditionally has ones of the highest injury and fatality rates. While combustion of gaseous fuels is studied reasonably well, as well as that of combustible dust, flame propagation in a combined gaseous-dusty environment, especially with a non-uniform dust distribution in a gas, remains an enigma that commands both fundamental and practical interests. While a planar premixed flame front would propagate steadily, with a certain speed L S with respect to the unburnt gas, such a flame occurs rarely in the practical reality. Indeed, the majority of industrial and laboratory flames are usually corrugated due to wall friction, in-built obstacles, turbulence, acoustics, shocks, combustion instabilities, etc. A corrugated flame front has a larger surface area relative to a planar one; therefore, it consumes more fuel per unit time and releases more heat, thus propagating faster than a planar flame front in the same mixture. Consequently, the continuous increase in the flame surface area is accompanied by flame acceleration.