ガスタービン翼後縁部球状ディンプル付きカットバック面フィルム冷却におけるブロー比の影響のLES解析

概要

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Cooling at trailing edge of gas turbine airfoil is one of the most difficult problems because of its thin shape: high thermal load from both surfaces, hard-to-cool geometry of narrow passages, and at the same time demand for structural strength. In this study, both heat transfer coefficient and film cooling effectiveness on pressure-side cutback surface were numerically simulated by using Large Eddy Simulation with a dynamic Smagorinsky model. Two different cutback geometries were examined: smooth and spherical-dimpled cutback surfaces. The Reynolds number of the main flow defined by the mean velocity and two times of the channel height was 20,000 and the blowing ratio was varied in the range of 0.5-1.5. The LES results were verified by the experimental results measured for the same geometry. The increase of the blowing ratio resulted in different tendencies between film cooling effectiveness and Nusselt number. The spherical dimple case showed 17% higher Net Heat Flux Reduction (NHFR) at most than the smooth case. The installation of dimples on cutback surfaces enhances film cooling performance.
2014-01-20