Resumen de Assessment of detailed combustion and soot models for high-fidelity aero-engine simulations
In recent years, interest in the development of efficient and clean aviation powerplants has increased due to the detrimental impact on health and the environment caused by conventional combustion systems. In this context, the research community has increasingly focused its efforts on the study of turbulent combustion and the generation of pollutant emissions such as soot particulates. With recent advances in computational power, high-fidelity simulations emerge as a valuable alternative to reproduce and analyze these phenomena. Specifically, Large Eddy Simulations (LES) are considered as one of the most promising numerical tools to provide further insight into the complex dynamic processes that characterize reactive turbulent flows and predict soot emissions in aeronautical applications.
In the present work, turbulent combustion and soot production is studied and analyzed in gas turbine engine applications by means of high-fidelity LES. Combustion modelling is addressed by a flexible tabulated chemistry method based on the flamelet concept, which is able to represent complex chemical phenomena with an affordable computational cost. In addition, an Eulerian- Lagrangian description is employed for the gas phase and droplets in order to correctly represent the multiphase flow in spray flames. A recently developed approach based on the sectional method and coupled to the tabulated chemistry framework is considered for soot prediction in computationally efficient simulations.
This numerical modelling framework is used in this work to analyze the combustion process and evaluate its capabilities to predict soot and flame characteristics in representative gas turbine burners. First, an atmospheric non-swirled spray flame is studied in terms of two-phase flow combustion. This burner shows a double reaction front structure and local extinction occurs in the inner layer due to both droplet-flame and turbulence-flame interactions, which is properly characterized by LES. Subsequently, combustion and soot production is investigated in a pressurized swirled model combustor which includes secondary dilution jets inside the combustion chamber. The assessment of the reacting flow field and soot is addressed for burner configurations with and without secondary air, showing excellent predictive capabilities in both cases. The present modelling approach accurately reproduce the complex swirled flow field, flame structure and soot dynamics and is able to provide different particle size distributions depending on the variations of the soot formation and oxidation processes.
In summary, the different practical cases studied allow to consolidate and validate the computational methodology followed in the present thesis. The proposed tabulated modelling strategy is sufficiently valid and suitable for reproducing complex combustion and soot formation phenomena, in view of the consistency of the analysis, the accurate predictions and the satisfactory agreement with the experimental measurements.
