Direct numerical simulation of turbulent lean methane-air bunsen flame with mixture inhomogeneities

Abstract

Direct Numerical Simulations of three-dimensional spatially developing turbulent slot Bunsen burner methane/air flames are performed. Three flames are simulated; they differ for the level of premixing of the fuel inlet: one has a fully premixed inlet, the other two have a partially premixed inlet that mimic a common injection strategy in stationary gas turbines. The jet consist of a methane/air mixture with global equivalence ratio ɸ = 0.7 and temperature of 800 K. The simulations are performed at 4 atm. The grid has a resolution of 20 μ m resulting in a total of 350 million points. Supporting simulations were performed to generate the inflow conditions for the jet. The velocity field and a fuel/air field were extracted from a fully developed channel simulation with scalar injection. Chemistry is treated with a new skeletal chemical mechanism developed specifically for the DNS. The data are analyzed to study possible influences of partial premixing on the flame structure and the combustion efficiency.