Simulação da combustão em motores a jato utilizando CFD

Abstract

Computational Fluid Dynamics (CFD), usually applied in the simulation of flows, combined with the simulation of chemical reactions is an interesting tool in the design and development of highly complex equipment, such as engines and combustors. In the present study, a computational simulation of combustion in a jet engine was performed using ANSYS Fluent software, initially using methane as the fuel, considering 5 chemical species along the combustion reactions involved, and then using Jet A, considering 32 chemical species involved in the combustion reactions. The simulated results were compared with simulated results from the literature, in addition to empirical data. The adopted model consisted of a Steady Diffusion Flamelet with chemical state relation, in addition to a non-adiabatic treatment, with a k-epsilon Realizable turbulence model. From the mathematical model and numerical procedure verified, a simulation of the combustion of commercial fuel Jet A (A2) was performed, in addition to the use of a geometry based on real models of jet engine combustors, demonstrating advantages mainly in relation to the computational cost involved. There was a substantial correlation between empirical and simulated data in the study with methane, in addition to a reduction in time per iteration in relation to the modeling reference found in the literature, allowing for deeper analysis, related to reaction kinetics, for example, such as profiles of concentration of intermediate reaction products, at lower computational costs. In the study with Jet A fuel, points of improvement in the geometry could be observed through the profiles of concentration, temperature, velocity, among others, making it possible to achieve greater efficiencies with the equipment in question and lower rates of generation of pollutants such as NOx that are generated in zones of high temperature and long residence times, in addition to enabling a better understanding of its operation.