Lean blow-out mechanism in a swirl-stabilized turbulent spray combustion in a realistic gas turbine combustor*

The present study involves identification of lean blow-out mechanism in a swirl-stabilized turbulent spray combustion in a realistic gas turbine combustor using large eddy simulation.  A modified Cartesian cut-cell technique and a gradient-adaptive mesh refinement are employed. Combustion is modeled using a finite rate chemistry approach with compact kinetic models for fuel chemistry. The subgrid stress tensor in the filtered momentum equation is evaluated by solving a transport equation for subgrid kinetic energy. Subgrid turbulence-chemistry interactions are accounted using a partially stirred reactor closure. The multiphase spray is modeled with discrete injections of droplets in a Lagrangian framework to simulate an air-blast atomizer. Injection droplet diameter distributions are derived from experiments. Lean blow-out calculations are carried out by the gradual reduction in the fuel flow rate. These results are further utilized to understand the physics of the lean blow-out process by studying the coupled interactions between fluid dynamics and combustion.