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Turbulence Heat and Mass Transfer 6. Proceedings of the Sixth International Symposium On Turbulence Heat and Mass Transfer
September, 14-18, 2009, Rome, Italy

DOI: 10.1615/ICHMT.2009.TurbulHeatMassTransf


ISBN Print: 978-1-56700-262-1

ISSN: 2377-2816

Large-Eddy Simulations of trailing-edge cutback film cooling at low blowing ratio

page 12
DOI: 10.1615/ICHMT.2009.TurbulHeatMassTransf.940
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ABSTRAKT

For high-pressure turbine blades, an efficient cooling of the trailing edge can be achieved by ejecting a cooling film into the flow over a cutback on the pressure side of the blade. Here, results of well-resolved Large Eddy Simulations (LES) are reported that match an existing experimental setup. A low blowing ratio M = 0:5 was chosen and compared to results for an engine-typical value of 1.1. Reasonably good agreement of mean velocity profiles and adiabatic cooling effectiveness with the experimental data was obtained. By imposing either laminar or time-dependent fully turbulent channel flow profiles within the coolant channel, the LES show that the flow regime of the coolant at ejection has a significant impact on the performance of the resulting cooling film for both blowing ratios. A surprising result is that, for the low blowing ratio, a turbulent coolant enables the cooling film to sustain a larger effectiveness farther downstream compared to a laminar coolant, whereas, for M = 1:1, the opposite is the case. This may be related to the different kinds of large coherent structures that are shown to be formed for the two cases.

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