XXXIX Meeting of the Italian Section of the Combustion Institute II2.1 NO x formation in a spatially developing turbulent premixed Bunsen flame S. Luca, A. Attili, F. Bisetti [email protected]King Abdullah University of Science and Technology (KAUST), Clean Combustion Research Center (CCRC), Thuwal, Saudi Arabia Abstract A Direct Numerical Simulation of a three-dimensional lean methane/air flame in a spatially developing turbulent slot Bunsen burner is performed. This configuration is of interest as it retains selected characteristics of real devices, such as turbulent production by mean shear. The jet consist of a methane/air mixture with equivalence ratio ϕ = 0.7 and temperature of 800 K. The simulation is performed at 4 atm. The coflow is composed of Argon at the temperature of the combustion products. The flame is in the thin-reaction zone regimes and the Reynolds number based on the jet width and velocity is 5600. The grid has a resolution of 20 μm resulting in a total of 350 million points. A supporting simulation is performed to generate the inflow conditions for the jet. Chemistry is treated with a new skeletal chemical mechanism developed specifically for the DNS with 33 species. The macroscopic and microscopic characteristics of the flame are analyzed. Due to the inert coflow, the flame develops from a location few millimeters above the nozzle. The flame structure is found to be similar to the one of one-dimensional premixed flame. Heat release rate and NO rate of formation are analyzed taking into account four paths of decomposition on N 2 as initiation steps for NO formation: NNH, Thermal, Prompt and N 2 O. Configuration & Numerical Methods The DNS configuration consists of a central premixed jet surrounded on both sides by a heated coflow. This arrangement is similar to the piloted flame used in experiments [1]. The jet is a methane/air mixture with equivalence ratio equal to ϕ = 0.7 and temperature of 800 K. The coflow is composed of Argon at the temperature of the combustion products. This temperature value is obtained from a fully burnt equilibrium solution with initial conditions equal to those imposed in the central jet. The choice of the coflow is made in order to stabilize the flame with the hot gas, without affecting NO x production with a coflow containing Nitrogen. A summary of relevant parameters of a freely propagating one-dimensional laminar flames is given in Table 1.
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x formation in a spatially developing turbulent premixed Bunsen flame · spatially developing turbulent slot Bunsen burner is performed. This configuration is of interest as it retains
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XXXIX Meeting of the Italian Section of the Combustion Institute