Combustion LES of a Multi-Burner Annular Aero-engine Combustor using a Skeletal Reaction Mechanism for Jet-A Air Mixtures

摘要

In this study we describe combustion simulations of a single sector and a fully annular generic multi-burner aero-engine combustor. The objectives are to facilitate the understanding of the flow, mixing and combustion processes to help improve the combustor design and the design process, as well as to show that it is now feasible to perform high-fidelity reacting flow simulations of full annular gas turbine combustors with realistic combustion chemistry. For this purpose we use a carefully validated finite rate chemistry Large Eddy Simulation (LES) model together with a range of reaction mechanisms for kerosene-air combustion. The influence of the chemical reaction mechanism on the predictive capability of the LES model, and on the resulting understanding of the combustion dynamics has recently been proved very important and here we extend this for kerosene-air combustion. As part of this work a separate study of different kerosene-air reaction mechanism is comprised, and based on this evaluation the most appropriate reaction mechanisms are used in the subsequent LES computations. A generic small aircraft or helicopter aero-engine combustor is used, and modeled both as a conventional single sector configuration and more appropriately as a fully annular multi-burner configuration. The single-sector and fully annular multi-burner LES predictions are similar but with the fully annular multi-burner configuration showing different combustion dynamics and mean temperature and velocity profiles. For the fully annular multi-burner combustor azimuthal pressure fluctuations are clearly observed, resulting in successive reattachment-detachment of the flames in the azimuthal direction.