Gas turbine combustors are used to extract chemical energy from the combustion of fuel in presence of an oxidizer to power turbines. Environmental concerns provide motivation to develop more efficient and less polluting gas turbine engines. To achieve good emission performance, lean burn combustors with low pollutant emissions have been developed. These combustors operate at fuel lean conditions and they can be classified into lean premixed and pre-vaporized (LPP) combustor, where the fuel and oxidizer are premixed and pre-vaporized to form a homogeneous mixture in a dedicated region, premixer, just before the fuel-oxidizer mixture enters the combustion chamber, and lean direct injection (LDI) combustor, where the fuel is directly injected into the flame zone without any premixing with oxidizer [1]. The premixing and pre-vaporizing reduce the residence time, the amount of time the gases are in the combustion chamber. The reduction in residence time reduces the NO x emissions, as the high NO x emissions are produced with a long residence time in the combustion chamber.The flow behavior of non-reacting and reacting flow in a lean premixed swirl combustor, adapted from KAUST experimental rig, has been studied using RANS in the commercial software, Ansys -Fluent. Turbulence is modeled using the two equation realizable k − model and the turbulence -chemistry interaction is modeled by a flamelet generated manifold (FGM) technique. At first, non-reacting flow was simulated in lean premixed swirl combustor. These simulation results were compared to the experiments done by Sabatino et al. [2] and LES work of Maestro et al. [3]. This non-reacting flow solution was used as an initial condition to the reacting flow for a faster convergence of the solution, with methane-air mixture at an equivalence ratio of 0.67. GRI 3.0 mechanism was used for modeling chemistry, which had 325 i I specially thank Dr. Urmila Ghia, for supporting me all the time. I would like to thank Ohio Supercomputer Center for letting me use the resources.I would like to thank my friends and people from work, for being patient, cooperative and supportive all these years in Cincinnati. All this could not be possible without my parents and my older brother. I so grateful to my parents and my brother for always believing in me.Their unconditional love and support always made me to dream big and achieve my dreams with ease. Finally, I am so thankful to my Master and Sir for their continuous blessings and guidance throughout my life . v
