Investigation of Heat Transfer and Flow Characteristics in Rotating Combined Three-Pass Channels

The combination cooling channels for the three-pass turbine blades are arranged based on the outer contour of the blades, with the flow area changing radially along the blades, and the channels arranged at certain angles to each other. In this study, the copper plate method was employed to investigate the heat transfer characteristics along the channels. The experimental fluid is air, and the maximum uncertainty of the Nusselt number is 7.99%. A detailed exploration of the flow and heat transfer patterns within the variable cross-section combined channels was conducted for Reynolds numbers ranging from 20,000 to 80,000 and rotation numbers ranging from 0 to 0.14. The research results indicate that as the flow area of the channel decreases, the flow accelerates, the disturbance effect of the ribs strengthens, and the heat transfer in the channel sharply increases. Rotation gradually increases the heat transfer difference between the leading side (LS) and trailing side (TS), but as the flow area decreases, the inertial effect strengthens, weakening the impact of rotation on heat transfer. Additionally, the numerical method was employed to study the coupling effects of each passage in the three-passage combined channels. The first passage and turning section enhance the turbulence of the flow but also introduce significant flow losses. Compared to split channels, the turning section leads to an increase in heat transfer in the second passage, but a decrease in heat transfer in the third passage.