Numerical analysis of heat transfer characteristics in ribbed two-passed channel with varied cross section

Abstract

The mid-chord region of turbine blades typically employs internal cooling channels to enhance heat transfer. However, traditional internal cooling channels are mostly designed in the form of straight channels, and studies based on it may not address the needs of variable cross section channels. Therefore, this study investigates the effect of rib configurations in variable cross section channels on channel performance. First, the cross sectional area of the two-passed channels is modified by altering the inclination angle of the dividers (−3°, 0°, and +3°). The flow pattern and heat transfer features within a two-passed channel with variable cross section under four different rib configurations of NP, NN, PN, and PP are investigated using numerical simulation. N denotes the ribs rotated 45° clockwise relative to the flow direction, while P denotes the ribs rotated 45° counterclockwise. Subsequently, the optimal rib configuration within the variable cross sectional two-passed channels is determined for Reynolds numbers ranging from 10 000 to 50 000. Results show that, at +3°, the PP exhibits the maximum decrease of up to 18.2% in transfer performance factor (TPF), while at −3°, the NN shows the maximum decrease of up to 12.7%. It is evident that the optimal rib configuration for two-passed channels under different divider inclinations is not consistent. At +3°, the NP exhibits the best TPF, while at −3°, the PP demonstrates the optimal TPF. This study provides insights into selecting appropriate rib configurations when the cross sectional area of internal channels within turbine blades varies. Compared to the studies that have focused on traditional straight channels, the research provides guidance for the design of ribbed two-passed channels with varied cross section.