## 3 Results and Discussion
### Comprehensive Performance under Rotating Condition  
When rotating, the channel often exhibits different characteristics due to the Coriolis force and centrifugal force. Taking \(Ro\) = 0.4 as an example, the differences of flow and heat exchange characteristics are discussed as follows. Figure 13 shows the streamlines of channels with different thickness turning vanes. Under the action of rotating Coriolis force, the cooling medium impinges the protrusion structure on \(\mathrm{RS}_{\mathrm{TR}}\). Then, the streamline near the wall surface presents a bifurcation state from \(\mathrm{RS}_{\mathrm{TR}}\) to \(\mathrm{RS}_{\mathrm{LE}}\). The fluid accelerates and strongly impacts the corner of the first turning region under the combined action of cross-section shrinkage effect and centrifugal force, resulting in a strong overturning flow in this area. Similar to the static condition, after the turning vane is arranged, the first turning region is in the state of impact and accelerated flow, and the second turning region changes from the overall spiral flow state to the spiral flow in the inner basin and uniform flow in the outer basin. The difference is that when rotating, the transverse flow of the cooling medium in pass2 is enhanced. The mainstream reattachment region in the upstream of pass2 and pass3 appear earlier. Rotation can diminish the flow separation area and improve the flow state there, which is same as the research results of [PERSON] et al. [29]. Figure 14 shows vorticity based on Q criterion and streamline counter at the same position as Figure 5. As shown in the figure, under the rotating condition, the wall vortex of the middle cross section of case1 removes from the \(\mathrm{RS}_{\mathrm{LE}}\) to the center of the channel. The high vorticity intensity area of the outlet cross section is distributed in a ladder shape with a wide trailing edge and a narrow leading edge. After the arrangement of the turning vane, the characteristics in case1 only exist in the inner basin. The high vorticity intensity area in the inner basin of the outlet section is significantly reduced compared with case1. As the thickness of the turning vane increase, the level of flow separation in this area decreases. The area decreases under rotating condition compared with that under stationary condition, which confirms the conclusion that rotation effect can improve the flow separation characteristics mentioned above. The end-wall vortex distributes on turning vane outer wall, and its strength and area increase along the flow  
Figure 12: The variation of \(TP\) with \(Re\) for different channels. direction. Unlike the static condition, the wall vortex in the inner basin shows a trend of detachment from the wall, and the end-wall vortex in the outer basin generates and detaches earlier. When rotating, the fluid flow state in the turning region is more disordered. Figure 15 presents the \(Nu\) counter of RS\({}_{\text{TR}}\) and RS\({}_{\text{LE}}\) in different channels. Since the Coriolis force is pointing from RS\({}_{\text{LE}}\) to RS\({}_{\text{TR}}\), the wall \(Nu\) of pass1 and pass3 has a relative relationship of 'RS\({}_{\text{TR}}\) > RS\({}_{\text{LE}}\)'. In pass2, the Coriolis force is pointing from RS\({}_{\text{TR}}\) to RS\({}_{\text{LE}}\), which is contrary to channel profile effect. Under the combined action of the two, the \(Nu\) presents a state of 'RS\({}_{\text{LE}}\) > RS\({}_{\text{TR}}\)'. Owing to the enhanced transverse motion of the fluid, the low \(Nu\) near the side of pass1 disappears, and the lateral uniformity of pass2 is improved. For case3 and case5, the inlet streamlines of pass2 and pass3 are more uniform and \(Nu\) is lower there. Unlike the stationary condition, the protrusion structure of the rotating trailing side of pass1 is strongly impacted by the cooling medium, which greatly increases the \(Nu\) on the windward side surface of the structure.