Analysis of Influence of Variable Airflow Distribution on Reactive Flow in a Gas Turbine Model Combustion Chamber

The objective of the present work is to investigate the influence of varying the percentage of distributed air flow rate via swirler, primary jets and dilution jets on reactive flow characteristics and NOX and CO emissions in a gas turbine model combustor. A Finite Volume staggered grid approach is employed to solve the governing equations that are linearized implicitly and also discretized by a second order method. The central difference discretization and second-order upwind schemes are applied respectively for the space derivatives of the diffusion and the advection terms in all transport equations. In the numerical simulation of reactive two-phase flow of this combustion chamber, the realizable k-ε turbulence model, steady flamelet combustion model and discrete ordinates radiation model have been used. The spray and atomization of liquid fuel droplet is modeled by an Eulerian–Lagrangian method. The present study is performed for four different cases of air injection and in the first case, boundary conditions are based on the laboratory conditions. After validation of the numerical results for the first case using experimental data, the subsequent cases are studied. Among the outcomes of the present work, the followings can be mentioned: comparison of velocity and temperature distributions, mass fraction percentage of the carbon dioxide, carbon monoxide and nitrogen oxide concentration at exit plane, as well as the formation method of flow structure in longitudinal cross-section of combustion chamber for the above-mentioned four reactive flow cases. Results show that the air distribution of the first case in laboratory conditions is not optimal and in the case where the air flow rate is reduced from the beginning to the end of the combustion chamber, the mass fraction of carbon monoxide and nitrogen oxide are minimum and the amount of carbon dioxide is maximum.