Numerical Investigation of Film Cooling over a Flat Plate with Varying Injection Angle

Document Type : Original Article

Authors

1 Libyan Armed Forces, Libya.

2 Egyptian Armed Forces, Egypt.

Abstract

Numerical investigations have been conducted in order to find appropriate turbulence model and near wall treatments to study the effect of injection angle. For this purpose, different turbulence models such as k- ε models (standard, RNG and realizable), and k- ω models (standard and the Shear Stress Transport (SST) model) were examined to solve for the most convenient accurate prediction of the flow field. In addition, two different wall functions (standard wall function and enhanced two-layer wall function were tested and compered with the experimental study at two blowing ratios (0.5, 1) and two injection angles (35o, 55o). It was found that the realizable k–ε model with enhanced all treatment (two-layer approach) was in reasonable agreement with experimental data, which proved its advantage as compared with other turbulence models. So the realizable k–ε model with enhanced wall treatment (two-layer approach) was selected in this paper to study the effect of injection angle variation. The film cooling geometry in the present paper is similar to that used in a previous study. The coolant flow temperature was kept constant at 188 K at a velocity 6.25 m/s and a constant density ratio of 1.6. The results showed a reduction in effectiveness for the injection angle of 55o as compared to effectiveness for the injection angle of 35o.

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