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Trailing Edge Film Cooling of Gas Turbine Airfoils - Effects of Ejection Lip Geometry on Film Cooling Effectiveness and Heat Transfer

Trailing Edge Film Cooling of Gas Turbine Airfoils - Effects of Ejection Lip Geometry on Film Cooling Effectiveness and Heat Transfer
Autor:

Horbach,T.
Schulz,A.
Bauer,H.-J.

Quelle:

Journal of Heat Transfer,
Vol. 41, No. 8, 2010
Turbine-09
International Symposium on Heat Transfer in Gas Turbine Systems
Antalya, Turkey, 9-14 August, 2009

Abstract

The present paper concentrates on trailing edge film-cooling of modern high-pressure turbine blades using cooling ejection through planar slots with a pressure side cutback. The experimental test section consists of a generic scaled-up trailing edge model. The effects of different geometric configurations on the structure and the performance of the cooling-film are investigated in terms of film-cooling effectiveness, heat transfer coefficients, and discharge behavior. The interaction between an internal turbulator array of ribs with the ejection slot lip is of major interest. Different designs of the cooling ejection lip are applied. Four different ratios of lip thickness to ejection slot height (t/H = 0.2, 0.5, 1.0, 1.5) are investigated and three different lip contours representing typical manufacturing imperfections and wear. The experiments are performed at engine-realistic density ratios. The blowing ratios are varied between 0.2 < M < 1.25. The results show a strong dependency on the ejection lip thickness and only marginal changes when the lip shape is varied.