Numerical simulation of a laboratory-scale turbulent slot flame

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 (20-species, 84-reaction) mechanism derived from the GRI-Mech 1.2 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.” The overall turbulent burning velocities of the simulation and experiment were, respectively, 2.45 and 2.55 times the laminar flame speed.