LARGE-EDDY SIMULATION OF TRANSIENT BEHAVIOR IN A COMBUSTION FIELD FOR GAS-TURBINE ENGINE

Combustion flow field in an industrial gas-turbine combustor was numerically investigated with a newly-developed turbulent combustion model. For turbulent model, large-eddy simulation technique was introduced to simulate unsteady phenomena in detail. The combustion model was based on a two-scalar flamelet approach coupling the two concepts of premixed and non-premixed flames expressed by the conservative scalar of mixture fraction and the levelset function of premixed flame surface, respectively. A fine full tetra computational mesh of 45.5 million cells and 7.7 million nodes was used to resolve turbulent fluctuation with high accuracy in the combustion field. The simulations were performed for two calculation conditions reproducing diffusion-like and premixed-like flames and for three conditions decreasing fuel inlet to investigate flame extinction behavior. It was indicated that premixed or partial premixed turbulent flames by complex burner system in the real scale combustor can be reasonably captured by the present simulation model.