IDOMENEO - Influence of temperature distributions on modern engine centre frames optimization

In today's attempt to reduce the emissions of pollutants, especially the greenhouse gas CO2, and to achieve more strictly limits, aero engine manufacturers try to reduce weight of their engines in order to reduce fuel consumption. This is done by lightweight designs and shorter engines due to smaller axial distance between blade and vanes. These measures also lead to shorter casing parts. Due to this development, the available time for hot streaks to mix out is reduced. Such hot streaks are typical for combustion chamber outlets and can be found in every engine. Therefore, it is assumed that such non-uniform temperature distribution from the outlet of the combustor (OTDF of app. 25%) will affect more downstream parts such as the Turbine Centre Frame (TCF) as well as the flow through these components. Because of aggressive TCF designs to additionally save weight of the engine, it is crucial to know the influence of hot streaks onto the flow through the TCF and the boundary layer that is close to separation. Further, the amount of cooling air should be reduced together with an increase of temperature level and pressure ratio to achieve higher efficiencies. But this leads to higher temperatures of the streak if the OTDF is nearly the same. The interaction of that hot streak with engine components reduces engine life time drastically or leads to fatal malfunctions of components in the hot gas path. Therefore, it is crucial to quantify these interactions and risks for the sake of safety, economics and environmental protection. These risks must be considered already during the design process. Within this project an annular sector cascade is designed, manufactured and brought into service in order to experimentally study the effect of hot streaks onto the aerodynamics and heat transfer to the TCF struts surfaces and end walls. As inlet condition an engine realistic flow field is simulated. The investigation is conducted for several radial and circumferential positions of the hot streak regarding to the leading edge of the TCF strut. The experimental investigation of this realistic effect under engine representative conditions goes beyond state-of-the-art.