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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-474-8

ISBN Online: 978-1-56700-473-1

International Heat Transfer Conference 16
August, 10-15, 2018, Beijing, China

EFFECTS OF HOLE GEOMETRY AND CURVED SURFACE ON FILM COOLING EFFECTIVENESS AND HEAT TRANSFER COEFFICIENT MEASURED WITH COMPENSATION OF THREE-DIMENSIONAL HEAT CONDUCTION

Get access (open in a dialog) DOI: 10.1615/IHTC16.ctm.023780
pages 4037-4042

Résumé

Effects of hole geometries (spanwise hole pitch, laidback length, and injection angle) on film cooling performance were experimentally investigated. Test sections with convex and concave surfaces had spanwise one row of arrowhead-shaped cooling holes. A steady-state thermographic method with compensation of three-dimensional heat conduction was adopted to measure detailed spatial distributions of both film cooling effectiveness and heat transfer coefficients for the convex and concave surfaces. Overall film cooling performance was also evaluated by Net Heat Flux Reduction (NHFR). Three-dimensional heat conduction analysis of the curved wall, which used measured temperatures as surface boundary conditions, was performed to calculate surface heat fluxes taking the wall heat conduction effects into consideration. The hole geometries were varied in the following ranges: spanwise hole pitches to a cooling hole diameter ratios of 4.0-9.0, laidback lengths to the diameter ratios of 0.90-4.50, and injection angles of 35-60 deg. Measurements were performed under a main-flow Reynolds number of 20,000 and three blowing ratios of 0.5, 1.0 and 1.5. In the present results, surface-averaged heat transfer coefficients for both convex and concave surfaces showed only a little variation due to the hole geometries and the blowing ratios. Surface-averaged film cooling effectiveness for the concave surface was lower than that for the convex surface, and it was insensitive to the blowing ratios. Higher surface-averaged values of NHFR were obtained for longer laidback length and smaller injection angle.