Numerical modeling and analysis of grooved surface applied to film cooling

In order to improve the efficiency of film cooling, numerical investigation was carried out to study the effects of different film-cooled plates on surface heat transfer. Both grooved and non-grooved surfaces were concerned. The modeling was performed using Fluent software with the adoption of Shear-Stress Transport (SST) k-ω model as the turbulence closure. The coolant was supplied by a single film cooling hole with an inclination angle of 30°. The Mach numbers for the coolant flow and the mainstream flow were fixed at 0 and 0.6, respectively. At three blowing ratios of 0.5, 1.0 and 1.5, the aerodynamic behaviour of the mixing process as well as the heat transfer performance of the film cooling were presented. The numerical results were validated using experimental data extracted from a benchmark test. Good agreements between numerical results and the experimental data were observed. For the film cooling efficiency, it shows that both local and laterally averaged cooling effectiveness can be improved by the non-smooth surface at different blowing ratios. Using the grooved surface, the turbulence intensity upon the plate can be reduced notably, and the mixing between the two flows is weakened due to the reduced turbulence level. The results indicate that the cooling effectiveness of film cooling can be enhanced by applying the grooved surface.

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