EFFECT OF SWIRL ON COMBUSTION CHARACTERISTICS IN NON-PREMIXED GAS TURBINE COMBUSTOR

Abstract

To stabilize the flame and reduce the pollutants, a combustion chamber needs to have recirculation. Air swirlers induce a swirling flow in order to ensure recirculation inside the combustion chamber. The flow field inside the combustor is influenced by the liner's dimensions and shape, the wall side holes' dimensions and shapes, and the primary air swirler's placement. The main consideration while developing swirlers is the swirl number (Sn). To obtain recirculation, swirl (Sn) needs to be greater than 0.6. This paper aims to optimize the design of a swirler considering the key elements of a non-premixed combustion chamber. CFD models are used to simulate this recirculation phenomenon. The findings show that at greater levels of swirl intensities, substantial radial and axial pressure gradients are created near the nozzle exit, leading to axial recirculation in the form of a central toroidal recirculation zone. Recirculation zone is also desirable for high combustor fficiency and uniform exit temperature profile. The mixing characteristics can be improved by the use of swirl in non-premixed combustion.