Many analyses in the literature have assessed the appropriate manner in which to scale an experimental test rig to represent film-cooled engine components. For conventional testing using low conductivity models, the key parameters are the mainstream Reynolds number, scaled coolant flow rate, and the adiabatic film effectiveness. The few studies that have sought scaling parameters for conjugate testing have identified that one must additionally match the heat transfer coefficient ratio between the internal and external surfaces and external Biot number. However, these analyses have focused on blade or nozzle regions with single or sparse film rows. The validity of this scaling approach to regions or components with substantial bore cooling contributions is unclear — for example the showerhead and/or platform of a blade or nozzle, or a component like a shroud. The present analysis outlines the drivers for potential departure from the accepted scaling. A numerical study is performed to assess potential errors due to the traditional scaling. The results of the analysis demonstrate that the additional parameter, the ratio of bore cooling to external heat transfer coefficient, is more appropriate in the near hole region especially in cases where film cooling is not significant.

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