The present study employs computational fluid dynamics (CFD) to explore the complexities of scaling film cooling performance measurements from ambient laboratory conditions to high temperature engine conditions. In this investigation, a single shaped hole is examined computationally at both engine and near ambient temperatures to understand the impact of temperature dependent properties on scaling film cooling performance. By varying select flow and thermal parameters for the low temperature cases and comparing the results to high temperature flow, the parameters which must be matched to scale film cooling performance are determined. The results show that only matching the density and mass flux ratios is insufficient for scaling to high temperatures. In accordance with convective heat transfer fundamentals, freestream and coolant Reynolds numbers and Prandtl numbers must also be matched to obtain scalable results. By virtue of the Prandtl number for air remaining nearly constant with temperature, the Prandtl number at ambient conditions is sufficiently matched to engine temperatures. However, laboratory limitations can prevent matching both the freestream and coolant Reynolds numbers simultaneously. By examining this trade-off, it is determined that matching the coolant Reynolds number produces the best scalability. It is also found that by averaging the adiabatic effectiveness of two experiments in which the freestream and coolant Reynolds number are matched, respectively, results in significantly better scalability for cases with a separated coolant jet.
Scaling of Film Cooling Performance From Ambient to Engine Temperatures
Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received September 9, 2014; final manuscript received September 27, 2014; published online December 30, 2014. Editor: Ronald S. Bunker.
This material is declared a work of the U.S. Government and is not subject to copyright protection in the United States. Approved for public release; distribution is unlimited.
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Greiner, N. J., Polanka, M. D., and Rutledge, J. L. (July 1, 2015). "Scaling of Film Cooling Performance From Ambient to Engine Temperatures." ASME. J. Turbomach. July 2015; 137(7): 071007. https://doi.org/10.1115/1.4029197
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