At the large scale turbine rig (LSTR) at Technische Universität Darmstadt, Darmstadt, Germany, the aerothermal interaction of combustor exit flow conditions on the subsequent turbine stage is examined. The rig resembles a high pressure turbine and is scaled to low Mach numbers. A baseline configuration with an axial inflow and a swirling inflow representative for a lean combustor is modeled by swirl generators, whose clocking position toward the nozzle guide vane (NGV) leading edge can be varied. A staggered double-row of cylindrical film cooling holes on the endwall is examined. The effect of swirling inflow on heat transfer and film cooling effectiveness is studied, while the coolant mass flux rate is varied. Nusselt numbers are calculated using infrared thermography and the auxiliary wall method. Boundary layer, turbulence, and five-hole probe measurements as well as numerical simulations complement the examination. The results for swirling inflow show a decrease of film cooling effectiveness of up to 35% and an increase of Nusselt numbers of 10–20% in comparison to the baseline case for low coolant mass flux rates. For higher coolant injection, the heat transfer is on a similar level as the baseline. The differences vary depending on the clocking position. The turbulence intensity is increased to 30% for swirling inflow.

In order to fully understand the physical behavior of lean burn combustors and its influence on high pressure turbine stages in modern jet engines, the use of Computational Fluid Dynamics (CFD) promises to be a valuable addition to experimental techniques. The numerical investigations of this paper are based on the Large Scale Turbine Rig (LSTR) at Technische Universität Darmstadt, Germany which has been set up to explore the aerothermal combustor turbine interaction. The underlying numerical grids of the simulations take account of the complex cooling design to the fullest extent, considering coolant cavities, cooling holes and vane trailing edge slots within the meshing process. In addition to the k-ω-SST turbulence model, Scale-Adaptive Simulation (SAS) is applied for a computational domain comprising swirl generator and nozzle guide vanes in order to overcome the shortcomings of eddy viscosity turbulence models with regard to streamline curvature. The numerical results are compared with Five Hole Probe measurements at different streamwise locations showing good agreement and allowing for a more detailed examination of the complex flow physics caused by the interaction of turbine flow with lean-burn combustion and advanced film-cooling concepts. Moreover, numerically predicted Nu-contours on the hub end wall of the nozzle guide vane are validated by means of Infrared Thermography measurements.

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The Large Scale Turbine Rig (LSTR) at Technische Universit ät Darmstadt, Germany is used to examine the aerothermal interaction of combustor exit flow conditions on the subsequent turbine stage. The rig resembles a high pressure turbine and is scaled to low Mach number conditions. A baseline configuration with axial, low-turbulent inflow and an aerodynamic inflow condition of a state-of-the-art lean combustor is modeled by the means of swirl generators, whose clocking position towards the nozzle guide vane’s leading edge can be varied. A hub side coolant injection consisting of a double-row of cylindrical holes is implemented to examine the impact on endwall cooling. This paper is directed to study the effect of swirling inflow on heat transfer and film cooling effectiveness on the hub side endwall. Nusselt numbers are calculated using infrared thermography and the auxiliary wall method. This method allows for a high spatial resolution and in addition also yields adiabatic wall temperature data within the same measurement using a superposition approach. Aerodynamic measurements and numerical simulations complement the examination. The results for the baseline case show Nusselt numbers to increase significantly with higher coolant mass flux rates for the whole endwall area. With swirling inflow, in general, a decrease of film cooling effectiveness and an increase of Nusselt numbers is observed for identical mass flux rates in comparison to the baseline case. The difference varies depending on clocking position.

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