Airbreathing Engine's Combustors. Part 1 : Operation and Main Physical Phenomena

Aeronautical combustors are not only critical in terms of performance and safety, but also in terms of reducing the environmental footprint of air transport (both in terms of decarbonization and improved air quality). To keep pace with the evolution of the technologies used, digital simulation is playing an increasingly important role, supported by increasingly powerful computing infrastructures and ongoing advances in physical modeling and software engineering. While experimental characterization of systems remains essential for direct access to the physical mechanisms involved, digital simulation provides access to all variables of interest to the engineer (pressure, velocity, temperature, mass fractions of different species, etc.) and to the entire volume of the configuration under study (including areas of space where access using a probe or laser would be complex, if not impossible), at no significant extra cost. What's more, the cost of producing a numerical simulation of a combustion chamber is often much lower than that of carrying out a test campaign, provided that a suitable model is chosen.

Given the scope of the subject, it will be covered in two articles in the Techniques de l'Ingénieur collection, which form a coherent "whole" but can also be read independently. In the first article, the various concepts needed to understand the major design issues for aeronautical combustors (operability, safety, limiting environmental impact, etc.) will be introduced. Next, the major physical phenomena occurring in these chambers (reactive turbulent flows, fuel fragmentation in droplet form, evaporation, radiative transfer) will be synthetically described. Finally, using the appropriate dimensionless numbers, the main regimes encountered in an aeronautical combustor will be highlighted for each phenomenon.

Thus, at the end of this article, a general picture of the operation and the main physical phenomena taking place in an aeronautical combustion chamber will have been painted, paving the way for the second article [TRP 4 012] "Aeronautical combustion chambers – Part 2: modelling and numerical simulation".