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Journal of Enhanced Heat Transfer

Impact factor: 0.244

ISSN Print: 1065-5131
ISSN Online: 1563-5074

Journal of Enhanced Heat Transfer

DOI: 10.1615/JEnhHeatTransf.v10.i4.70
pages 431-444

Effects of Rib Height on Heat Transfer Performance Inside a High Aspect Ratio Channel with Inclined Ribs

Robert Kiml
Tokyo University of Agriculture and Technology, Department of Mechanical Systems Engineering, Koganei-shi,Nakacho 2-24-16,Tokyo 184-8588, Japan
Sadanari Mochizuki
Tokyo University of Agriculture and Technology, 2-24-16, Naka-cho, Koganei-shi, Tokyo 184, JAPAN
Akira Murata
Department of Mechanical Systems Engineering, Tokyo University of Agriculture and Technology, Koganei-shi, Tokyo 184-8588, Japan

ABSTRACT

Heat transfer and pressure drop experiments were performed in a rectangular high aspect ratio channel (5:1, 45 ґ 9 mm) representing a turbine blade trailing edge cooling passage. The oblique ribs were attached to two opposing long side walls and were intended to function as secondary flow inducers as well as turbulators to improve the heat transfer of the both rib-roughened and rear (one of the short side walls) walls. The experiments were performed for three rib heights—h = 3 mm, h = 2 mm, and h = 1 mm (h-rib height)—for two rib arrangements, transverse (90°) and inclined (60°). It was verified that (1) the heat transfer enhancement on the rear wall was attributed to the rib-induced secondary flow, which carries the cold air from the passage core region toward the rear wall and enhances the heat transfer appreciably; and (2) heat transfer and pressure drop strongly deteriorate with a decreasing rib height because of the weakening of the rib-induced positive effects as a turbulence promoter and secondary flow inducer.