Effect of Fuel Particle Size on the Stability of Swirl Stabilized Flame in a Gas Turbine Combustor

摘要

Combustion stability is examined in a swirl stabilized aero gas turbine combustor using computational fluid dynamics. A 22.5 degrees sector of an annular combustor is modeled for the study. Unstructured tetrahedral meshes comprising 1.2 x 10(6) elements are employed in the model where the governing equations are solved using CFD flow solver CFX using eddy dissipation combustion model. The effect of fuel particle size on the combustion and its stability has been studied at steady state and transient conditions. The time for complete evaporation is increased exponentially when drop size increases. It delays heating up the mixture and subsequent ignition. This strongly affects the stability of the combustion flame as the incoming fresh mixture will have a quenching effect on the existing temperature field. Transient analysis at low fuel-air ratio and high particle size shows that there is a series of flame extinction and re-ignition prior to complete extinction which is observed from the fluctuation of gas temperature in the primary zone.