Flow and heat transfer of the rotating composite cooling channel with axial jet holes

Research on turbine blade internal cooling channels is gradually transitioning from simplified structural channels to more intricate ones that closely approximate actual blade cooling channels. The present study conducts an experimental and numerical research to investigate the flow and heat transfer behaviors within a composite cooling channel under static and rotating states. The studied composite channel contains a U-shaped channel and a lateral outflow pin-fins channel, which are interlinked by middle axial jet holes. The inlet Reynolds number ( Re ), temperature ratio (TR), and rotation number (Ro) studied vary from 10,000 to 40,000, 0.07 to 0.14, and 0 to 0.33, respectively. Under static states, axial jet inflow along the pass can avoid the formation of low heat transfer zones within pin-fins channel. Axial jets impact on pin-fins can increase heat transfer by 17 % to 28 %. Under rotating states, the lateral outflow by axial jet holes can weaken rotating influence and reduce heat transfer discrepancy between the leading and trailing walls of the second pass. Along the second pass, the reduction in fluid velocity results in a trade-off between Coriolis force and buoyancy force, which has a significant effect on secondary flow, resulting in a higher heat transfer on the leading wall at TR = 0.07 than TR = 0.14, with a difference of up to 27 % in some zones. The axial inflow avoids the influence of Coriolis force, thereby ensuring consistency in heat transfer on the leading and trailing walls of pin-fins channel. Moreover, the flow resistance is also investigated.