H2-TCF - Aerothermal investigation of an aggressive turbine intermediate casing in the new stress field of hydrogen combustion

H2-TCF is an experimental test campaign to measure heat transfer and purge film cooling in an aerodynamically aggressive turbine center frame with non-turning structural Vanes (TCF) in within the new field of tension of hydrogen combustion. Due to the ever increasing turbine inlet temperature in an engine and the hot streaks from the combustor, which will be much more intense due to the use ofhydrogen, the TCF will become a thermally critical component in the future. In very simplified terms, hot streaks are the local temperature maxima downstream ofthe combustion chamber flames. These hot streaks are also still present at the TCF inlet with high intensity. Already today, TCF inlet temperatures are 1000°C.This is just about tolerated by the component without external cooling. Due to the increasing turbine inlet temperature and the hot-streaks intensified byhydrogen combustion, a comprehensive heat transfer investigation of this component is now indispensable. Furthermore, the cooling potential of the alreadyexisting high-pressure turbine purge air, primarily used to seal the cavities of the turbine, in the TCF shall be investigated, especially in the presence of hot-streaks. There was already a previous project (Opti-TCF) at ITTM on heat transfer in this TCF where a turbine (HPT) was running upstream. The results from Opti-TCF were so complex that only the quantification of the heat transfer was possible but not a full comprehension of the underlying mechanisms. Thisunderstanding, however, is essential for the sucessful introduction of hydrogen in aero engines. This will be solved with H2-TCF. The used test rig (AnCa) has modular components or inserts upstream of the TCF that gradually approximate the complexdownstream flow of a turbine. In addition, a hot-streak generator that can be installed in a modular fashion will also be used, allowing to study the influence andmigration of hot-streaks in the TCF. It is expected that the flow phenomena, which all occurred simultaneously and superimposed in Opti-TCF, will gradually adjust by adding the modularcomponents and inserts in the AnCa, allowing a deep understanding of the heat transfer and purge film cooling of the TCF to be derived. This understanding willthen be used to calibrate CFD simulations and create models that will allow to estimate the behavior of this component in the future. Furthermore, a statementcan be made as to whether the current TCF designs are at all suitable for more intense hot-streaks caused by hydrogen combustion and whether hydrogen istherefore drop-in capable from the point of view of the current TCFs. In international comparison with other investigations and especially in comparison with the FFG project IDOMENEO (874530), H2-TCF is the first project toinvestigate a state-of-the-art TCF with modular inflow conditions, purge cooling and a modular hot-streak generator. Thus, the interaction of the hot streaks withthe purge cooling films and the modular inflow conditions is especially investigated here. This is an absolute novelty. Besides its predecessor Opti-TCF, it is thefirst investigation ever to consider and investigate the cooling effect of purge air from the upstream turbine. In particular, we anticipate that the interactionsbetween hot-streak, purge air, and modular internals will produce highly non-trivial flow effects and phenomena. Knowledge of these will greatly accelerate thedesign of the hydrogen-capable TCF of the future.