Invoking Pre-Rotation Induced Flow to Improve the Performance of Gas Turbine Film Cooling

Abstract

The present study proposes a novel method to improve the performance of film cooling. In this type of cooling, due to the presence of counter-rotating vortex pairs downstream of the injection hole, the formed film on the surface tends to detach from the surface. A new geometry is proposed to overcome this vortex pair. In this geometry, the injection passage is equipped with one or more helical ribs. These ribs induce rotation in the injected cooling fluid flow which prevents the separation of the coolant film from the surface. Analysis and optimization of the effective parameters are done including the injection angle, the height, thickness, number, and pitch of the ribs. The results show that by exceeding the injection angle from an optimum value, the mixing tendency of the injected fluid and main flow increases, and the cold fluid film liftoff occurs faster. On the other hand, as this angle decreases, the pressure drop rises. Considering both the heat transfer and pressure drop effects, the best performance is observed at the injection angle of 20°. Moreover, the best performance is achieved for the ribbed passage (of D diameter) with two ribs of 0.025D ​​thickness, 0.1D height, and 0.33D rib pitch.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

Mohamad Abolhasani-Moghadam

Mohamad Abolhasani-Moghadam obtained his B.Sc. and M. Sc. degrees in fluid mechanics and energy conversion from the Isfahan University of Technology, Isfahan, Iran. Currently, he is a Ph.D. candidate in energy conversion at the same university. His research interests are heat transfer, electronics cooling, and computational fluid dynamics.

Mohammad Reza Salimpour

Mohammad Reza Salimpour is a professor of thermal sciences in the Department of Mechanical Engineering, at the Isfahan University of Technology, Isfahan, Iran. He received his B.Sc., M.Sc., and Ph.D. in mechanical engineering from the University of Tehran in 2001, 2003, and 2007, respectively. His major research areas are heat transfer, electronics cooling, two-phase flow, and thermal design.