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Increasing Adiabatic Film-Cooling Effectiveness by Using an Upstream Ramp

[+] Author Affiliations
S. Na, T. I.-P. Shih

Iowa State University, Ames, IA

Paper No. GT2006-91163, pp. 931-938; 8 pages
  • ASME Turbo Expo 2006: Power for Land, Sea, and Air
  • Volume 3: Heat Transfer, Parts A and B
  • Barcelona, Spain, May 8–11, 2006
  • Conference Sponsors: International Gas Turbine Institute
  • ISBN: 0-7918-4238-X | eISBN: 0-7918-3774-2
  • Copyright © 2006 by ASME


A new design concept is presented to increase the adiabatic effectiveness of film cooling jets without unduly increasing surface heat transfer and pressure loss. Instead of shaping the film-cooling hole at its downstream end as is done for shaped holes, this study proposes a geometry modification upstream of the film-cooling hole to modify the approaching boundary-layer flow and its interaction with the film-cooling jet. Computations, based on the ensemble-averaged Navier-Stokes equations closed by the realizable k-ε turbulence model, were used to examine the usefulness of making the surface just upstream of the film-cooling hole into a ramp with backward-facing step. The effects of the following parameters were investigated: angle of the ramp (8.5°, 10°, 14°), distance between the backward-facing step of the ramp and the film-cooling hole (0.5D, D), and blowing ratio (0.36, 0.49, 0.56, 0.98). Results obtained show that an upstream ramp with a backward-facing step can greatly increase film-cooling adiabatic effectiveness. The laterally averaged adiabatic effectiveness with ramp can be two or more times higher than without the ramp. Also, the ramp increases the surface area that each film-cooling jet protects. However, using the ramp does increase drag. The increase in surface heat transfer was found to be minimal.

Copyright © 2006 by ASME
Topics: Cooling



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