Numerical simulation of a laboratory-scale turbulent slot flame

Abstract

We present three-dimensional, time-dependent simulations of the flowfield of a laboratory-scale slot burner. The simulations are performed using an adaptive time-dependent low Mach number combustion algorithm based on a second-order projection formulation that conserves both species mass and total enthalpy. The methodology incorporates detailed chemical kinetics and a mixture model for differential species diffusion. Methane chemistry and transport are modeled using the DRM-19 mechanism along with its associated thermodynamics and transport databases. Adaptive mesh refinement dynamically resolves the flame and turbulent structures. Detailed comparisons with experimental measurements show that the computational results provide a good prediction of the flame height, the shape of the time-averaged parabolic flame surface area, and the global consumption speed (the volume per second of reactants consumed divided by the area of the time-averaged flame). The thickness of the computed flame brush increases in the streamwise direction, and the flame surface density profiles display the same general shapes as the experiment. The structure of the simulated flame also matches the experiment; reaction layers are thin (typically thinner than 1 mm) and the wavelengths of large wrinkles are 5-10 mm. Wrinkles amplify to become long fingers of reactants which burn through at a neck region, forming isolated pockets of reactants. Thus both the simulated flame and the experiment are in the "corrugated flamelet regime."

Subgrid Scale Modeling in Large-Eddy Simulation of Turbulent Combustion Using Premixed Flamelet Chemistry

“…The flame is similar to the flames studied by Filatyev et al [9], Bell et al [10], and Sankaran et al [11], with parameters somewhat altered in our case, to enable direct numerical simulation (DNS) with moderate computational effort. Both LES and DNS in the present paper assume flamelet chemistry, but unlike LES, the DNS resolves both flame thickness and turbulence down to the Kolmogorov length-scale.…”

Three-dimensional direct numerical simulation of turbulent lean premixed methane combustion with detailed kinetics

“…Bell et al [5] produced the first simulation of a turbulent methane flame in three dimensions with moderate-fidelity kinetics using DRM-19, which 20 is a simplified mechanism derived from GRIMech 1.2. Simulations using DRM-19 for a variety of experimental configuration have been presented in [6,7]. Sankaran et al [8] performed a DNS of the lean premixed preheated methane flame stabilised on a slot burner using a skeletal mechanism with 13 species derived from GRIMech 1.2.…”

A hypothetical burning-velocity formula for very lean hydrogen–air mixtures

“…This software is the product of the mathematical and computational research reported in [27,[30][31][32] and references therein. Calculations made with this methodology compare well with turbulent flame experiments [33,34] The calculations reported here consider a hydrogen-air mixture with equivalence ratio φ=0.2 (volume of fuel 7.75%) which does not appear to support a planar flame at standard temperatures and pressures. The percentage of fuel is above the listed [35] flammability limit (4%) but between the values (4% and 9%) reported (e. g. [15], p.10) for upwardly and downwardly propagating, non-planar flames.…”