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Momentum-Preserving Film-Cooling Shaped Holes
Category(s):
For Information, Contact:
Jay Bjerke
Commercialization Manager, Engineering
515-294-4740
licensing@iastate.edu
Web Published:
5/7/2015
ISURF #
3458
Summary:
Iowa State University researchers have developed a new shape-hole design concept to enable more effective film-cooling for gas turbine engines and other applications.

Development Stage:
Description:
Film cooling is a widely used method to protect materials exposed to hot gases whose temperatures may exceed the melting temperature of the materials, for example in gas turbine engines used in aerospace and power generation.  Film cooling protects the material by injecting a layer of cooler air to insulate the material surface from the hot gas; however, it can be inefficient because film-cooling jets can lift off from the material surface that they are intended to protect and draw in or entrain hot gases underneath them.  In addition, film-cooling can increase drag.  Previous efforts to improve the effectiveness of film cooling include shaping the hole near its exit, using slots instead of circular holes, placing tabs at the exit of holes, indenting a region around the film cooling hole, and using compound angles.  However, these efforts may not enable sufficient cooling to satisfy the increasingly higher inlet temperatures desired for maximum efficiency of gas turbine engines or may result in an unacceptable increase in drag.  For example, while previous shaped hole designs have lead to an increase lateral spreading, downstream penetration of the coolant was reduced because the expanding cross-sectional area decreased the momentum of the cooling flow.  To overcome these deficiencies, ISU researchers have developed a new film-cooling shaped hole design that preserves momentum for greater lateral and streamwise coverage.  As a result, significant improvement in film-cooling effectiveness especially at low blowing ratios is observed.

Group:
Advantage:
• Keeps the film-cooling flow cross-sectional area nearly constant so that momentum can be preserved to increase both lateral and streamwise coverage of the film-cooling jet.
Application:
Turbine cooling; film cooling

References:
Patent Information:
*To see the full version of the patent(s), follow the link below, then click on "Images" button.
Country Serial No. Patent No. Issued Date
United States 11/975,064 7,997,867* 8/16/2011


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