Numerical Investigation of the Effect of Coolant Injection Angle on the Pulsed Film Cooling Effectiveness of Square Wave Flow on Flat Plate

Document Type : Research Article

Authors

1 energy transfer,mechanical engineering,semnan university,semnan,iran

2 Mechanical Engineering Department, Semnan University

3 Department of mechanical engineering

Abstract

The effect of the angle of injection on the film cooling effectiveness with square wave pulsation is investigated at various frequencies. Four angles of injection are selected at 20, 25, 30 and 35 degrees. Film cooling is used to cool turbine blades and extend the life of blade. The pulsed flow is investigated at three frequencies of 2, 50 and 500 Hz. Finite volume method is used to solve the flow governing equations. The shear stress transport k-ω model is used to model the turbulence. The obtained results showed that the injection angle of 20 to 25 degrees had the most film cooling effectiveness for all frequencies. In higher frequency, 500 Hz, it is observed an increase in the effectiveness of the film cooling in close distances after the injection holes. At far distances, the lower frequency, 2 Hz, produces the most effectiveness. The largest difference in centerline effectiveness is achieved at 500 Hz for hole angles of 20 to 35 degrees with a value of 64.3%. This value is 98.9% for lateral effectiveness. As the frequency increases, the cooling mass flow interruptions are reduced, and as a result, the instantaneous effectiveness shows a slower variation than the lower frequencies. The blowing ratio of 0.5 had the most value in comparison with the blowing ratio of 0.75 and 1 in all angles and frequencies. The maximum difference in effectiveness is 187.4% for blowing ratio of 0.5, in comparison with the other two blowing ratios.

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References

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Amirkabir Journal of Mechanical Engineering
Volume 52, Issue 6
September 2020
Pages 1641-1658

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