Large-Eddy Simulation of the lean-premixed PRECCINSTA burner with wall heat loss

Swirl burners are widely used in aeronautical engines and industrial gas turbines. These burners enhance the flame stabilization by bringing back hot products to the reactive zone and their topology ensures a good compactness. However, the outer recirculation zones created in these burners induce wall heat loss that affects the flame structure. This paper proposes a numerical strategy based on Large-Eddy Simulation (LES) and non-adiabatic boundary conditions with a skeletal chemistry approach coupled to the Dynamic Thickened Flame model (TFLES). Simulations were performed on the PRECCINSTA burner with meshes up to 877 millions elements. Results demonstrated the impact of the addition of wall heat loss on the lift-off of the external flame front, leading to a flame topology change from a M-shape to a V-shape. This lift-off height increases with the grid resolution showing the strong influence of the mesh resolution on the flame topology. Comparisons of the non-adiabatic LES results on the finest mesh with the experimental data show an unprecedented agreement. The flame quenching process is analyzed and exhibits the role of strain rate which controls the level of penetration of cooled products within the inner reaction zone. (C) 2018 The Combustion Institute. Published by Elsevier Inc. All rights reserved.