Large-Eddy Simulation in an Industrial Gasturbine Combustor for NOx Prediction

NOx emission reduction is important for developing gas-turbine engines. Predicting the thermal profile and pollutant-emission factor by numerical simulation is effective for reducing the development costs. Here a large eddy simulation coupled with a 2-scalar flamelet approach is applied to the numerical analysis of an industrial gas-turbine combustor. The combustor of an L20A-DLE gas-turbine engine is calculated. Combustor performance under different loads is investigated. NOx production decreases with reducing load, and this tendency agrees well with the experimental results. It is said that NOx production due to a large amount of supplemental burner fuel. NOx production in the simulation is lower than in the experiment. The simulated temperature in the combustor outlet is also lower than the adiabatic temperature. Moreover, the fuel is not burned completely within the combustor region. The difference in the combustion status in a supplemental burner is investigated. For the diffusion flame, a high-temperature region is observed locally owing to the presence of a fuel-rich region. For NOx production, NOx emission reduction is expected using a burner that introduces a premixed flame. From the simulation results, we can estimate NOx production in a gas-turbine combustor. The tendencies in the differences of the loads agreed well with the experimental data, and the superiority of a premixed flame was indicated.