Aero-Thermal Analysis of Combustor/Turbine Interaction in Aero-Engines: the Challenge of today

Design practice for future development of aero-engines will take into account component interaction from both the aero-thermal and the aero-acoustic point of view. In particular, improved understanding of physical phenomena characterizing the combustor/turbine interaction (including metal parts) will enable a further optimization of such components, leading to an increased performance of new generation of engines. Lean-burn combustion technology has been identified to be the key  methodology for gas turbine combustion  systems to achieve legislative requirements for NOx emissions. Currently it is a mature technology in the power generation field but is still on development for aero engines. Combustors on which this type of combustion is implemented are characterized, in general, by high swirl numbers in order to provide adequate flame stabilization. Moreover, they are characterized by a reduction, or total absence, of dilution jets upstream to the turbine entry section. Such peculiarities make the aero-thermal field on the combustor/turbine interface very “aggressive”, being characterized by temperature non-uniformities, residual swirl and high turbulence intensity. Given the growing interest in the topic by industry, the present work aims to investigate, from a numerical point of view, the aero-thermal  aspects that characterize combustor/turbine interaction. Despite a large number of studies has been dedicated in scientific literature in the past, especially concerning hot streaks migration in turbine stages, comprehensive  studies of the combustor/turbine interaction are still very limited.

The presentation wants to  focus the actual trends and the key points from numerical as well  phenomenological point of view  in this frontier  sector where Turbine  is  strongly   involved as key element  in the energy conversion chain. The aim  is to discuss challenges and recent progresses in the understanding of the transport and mixing mechanisms taking place between the different components.