CFD-based Parametric Study of Swirl Effects on Combustion in Industrial Natural Gas Combustor

Accurate prediction of the temperature and various species concentrations at combustor exhaust is very important. This work presents numerical investigations of a can-type combustor used in industrial gas turbines for power generation. The methane-air combustion process is investigated using models based on Reynolds-averaged Navier-Stokes (RANS) equations. Enhancement of the mixing of air and fuel streams, which results in better combustion, is numerically investigated using different swirl rates. The investigation explores different combinations of turbulence, combustion, and radiation models to find the best possible combination that could accurately predict the combustion process. The numerical results are validated with the extensive experimental database available in the open literature. A structured grid is used to investigate the effect of different modelling parameters as it turned out to reduce the computational power and simulation time. It is found that a swirl improves the combustion process by forming recirculation zones of different lengths and time scales. The combustion lengths are reduced by the entrainment and rapid mixing of the reactants in the recirculation zones.