3次元熱伝導を考慮した過渡応答法によるディンプル面の熱伝達特性の計測 : ディンプル前縁・後縁傾斜の影響

概要

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Recently, heat transfer enhancement with dimples is becoming attractive for internal cooling of gas turbine blade because it induces small pressure loss. As compared to spherical dimples, teardrop-shaped dimples which have straight slope at leading edge showed higher heat transfer by suppressing flow separation at the leading edge. However, mechanism of heat transfer enhancement is not well understood especially with respect to the relation to the flow field. In this study, for three types of dimples (spherical, teardrop with leading- or trailing-edge slope), heat transfer experiment by using transient technique with compensation of three-dimensional heat conduction was performed for Re=16000-36000. In addition, flow visualization with combination of oil-film method and PIV was performed for Re=30000. The present results clearly showed the areas of flow separation and reattachment and the role of leading- and trailing-edge slopes on the heat transfer. The heat transfer at the same blowing power was the highest for the teardrop-shaped dimple with leading-edge slope, and it was higher than the spherical and teardrop-shaped dimple with trailing-edge slope by 17% and 53%, respectively, at Re=36000.
公益社団法人日本ガスタービン学会の論文
2012-11-20