Combined effects of bleed hole extraction and rotation on internal heat transfer in a ribbed two-pass channel

Serpentine passages arranged with ribs, are commonly used to guide the cooling air and remove heat transferred from hot gas. In this study, the effects of bleed hole extraction on internal heat transfer of ribbed channel are numerically studied in a rotating frame. Three positions of bleed hole are studied as rotation number ranges from 0 to 0.2. The flow structure and heat transfer features are depicted and evaluated through qualitative and quantitative analysis. Numerical results reveal that heat transfer distribution features are quite different for channel with bleed holes at different locations. The allocation of bleed hole extraction flowrate varies distinctively under rotating condition. Rotation is responsible for affecting the flow reattachment and corresponding secondary vortex structures, and consequently heat transfer features. Channels rotated in clockwise and counter-clockwise direction share opposite Coriolis force acting direction, thus effects of heat transfer augmentation are different. The effects of bleed hole position on local heat transfer are more pronounced on the endwall opposite to the endwall where the Coriolis force acts. Channel with bleed holes at upstream position shows the poorest heat transfer enhancement at inter-rib regions, with maximum reduction by 11.4% under stationary condition and 13.2% under rotating condition.