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Open AccessArticle

Effects of Flow Oscillations in the Mainstream on Film Cooling

1
Graduate Program in Acoustics, The Pennsylvania State University, University Park, PA 16802, USA
2
Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802, USA
*
Author to whom correspondence should be addressed.
Inventions 2018, 3(4), 73; https://doi.org/10.3390/inventions3040073
Received: 13 July 2018 / Revised: 15 September 2018 / Accepted: 11 October 2018 / Published: 24 October 2018
(This article belongs to the Special Issue Heat Transfer and Its Innovative Applications)
The objective of this study is to investigate the effects of oscillations in the main flow and the coolant jets on film cooling at various frequencies (0 to 2144 Hz) at low and high average blowing ratios. Numerical simulations are performed using LES Smagorinsky–Lilly turbulence model for calculation of the adiabatic film cooling effectiveness and using the DES Realizable k-epsilon turbulence model for obtaining the Stanton number ratios (St/Sto). Additionally, multi-frequency inlet velocities are applied to the main and coolant flows to explore the effects of multi-frequency unsteady flows and the results are compared to those at single frequencies. The results show that at a low average blowing ratio (M = 0.5) if the oscillation frequency is increased from 0 to 180 Hz, the effectiveness decreases and the Stanton number ratio increases. However, when the frequency goes from 180 to 268 Hz, the effectiveness sharply increases and the Stanton number ratio increases slightly. If the frequency changes from 268 to 1072 Hz, the film cooling effectiveness decreases and the Stanton number ratio increases slightly. If the frequency goes from 1072 to 2144 Hz, the film cooling effectiveness climbs up and the Stanton number ratio decreases. The results show that at high average blowing ratio (M = 1.0) the trends of the film cooling effectiveness are similar to those at low blowing ratio (M = 0.5) except from 0 to 90 Hz. If the frequency goes from 0 to 90 Hz at M = 1.0, the film cooling effectiveness increases and the Stanton number ratio decreases. It can be said that it is important to include the effects of oscillating flows when designing film cooling systems for a gas turbine. View Full-Text
Keywords: turbulent flows; numerical simulation; film cooling effectiveness; Stanton number ratio turbulent flows; numerical simulation; film cooling effectiveness; Stanton number ratio
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Baek, S.I.; Yavuzkurt, S. Effects of Flow Oscillations in the Mainstream on Film Cooling. Inventions 2018, 3, 73.

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