CFD coupling of a swirl injector to a lean premixed gas turbine combustor

Computational Fluid Dynamics (CFD) provides valuable insights into combustion processes in gas turbines, aiding components optimization. Current limitations include computational resource requirements for simulation. The complexity of reactive analysis implies high computational costs. The purpose of this study is to demonstrate the effectiveness and applicability of an alternative methodology, conceived to reduce the computational time of reactive simulation. In this thesis, a CFD analysis is performed on a simple model of an annular combustor using the proposed approach. Whereas the typical geometric model employed for simulation, comprises the combustion chamber, injection system, and mixing devices; herein, the geometry consists solely of the combustion chamber. The coupling between the injection system and the combustor is achieved through the utilization of the variables profiles such as species and temperature distribution together with the flow velocities obtained from a prior independent analysis of the injector. In this thesis, the first step involves the extraction of the fluid volume through a simplification of the combustor, specifically, it is a 30-degree sector of the complete geometry to exploit periodicity. The next step is the extrapolation of variable profiles from the previous simulation to be used as boundary conditions for the combustion chamber. It is important to emphasize that, all previous simulations exploited the swirler periodicity, thus reducing considerably computational time. At this point, the adaptation throughout rotation, translation, and duplication of the profiles is addressed with an in-house developed routine between the two components. This constitutes a crucial step for the exploitation of periodicity, both for injector and combustor, while ensuring proper coupling between the two. Velocity profiles are of major importance, in order to enable the retention of the swirl and mixing information within the chamber, without incorporating the injector into the control volume. The final steps are more canonical, involving cold flow analysis followed by reactive simulation of the combustion process. The outcome of this approach is underscored by two aspects: firstly, it facilitates the analysis of the components through the split into two different domains, by retaining at the same time crucial information such as flow stratification and direction without involving well-premixed assumptions. The results obtained from these analyses, lead to the conclusion that this novel methodology is robust and effective to divide the study of the combustor and the injector while reducing computational time.