Effects of a high Reynolds number and rotation on the leading-edge heat transfer of a ribbed cooling channel with a cross-section consisting of a semicircle and a rectangle

Owing to the recent increase in the demand for gas turbines with increased thrust, efficiency, and performances, the optimization of the heat transfer performance is necessary. In this study, the heat transfer performance in a combined-shaped cooling channel with angled ribs was investigated experimentally. The channel cross-section (D_h = 18.23 mm) was composed of a semicircle and a rectangle, which is appropriate for simulating a turbine blade leading-edge. The rib angle was 60° and staggered, and it was placed on the trailing and leading surfaces with a pitch-to-height ratio (P/e) of 10.0. The effects of the Reynolds number and rotation were studied. The Reynolds number varied from 18000 to 63000, and the rotation number ranged from 0 to 0.8. The results revealed that in the non-rotating ribbed channel, the Nu/Nu₀ ratio along the streamwise direction first increased and then decreased slightly after a peak, followed by an increase. The Nu/Nu₀ ratio reached a maximum of 6.4 in the rotating channel, and was greater than that in the non-rotating channel by a factor of 1.79. It was found that owing to the rib–rotation interaction, the Nu/Nu_s ratio exhibited different trends with an increase in Ro at different measurement points with small and large radii. The findings can serve as the basis for the development of high-performance gas turbines with increased thrust and efficiency.