## 3 Results and Discussion
### Influence on Unsteady Wake Transport in AITD  
Figure 8 shows the circumferential distribution of the turbulence intensity (T\({}_{\text{u}}\)) at the midspan of different streamwise sections inside the AITD. As shown in Section B1, the width and intensity of the wakes increased significantly with increasing \(d/s\) value. Taking the case of \(d/s\) = 0.122 as an example, the wake width (\(w\)/\(s\) = 0.464) and the peak turbulence intensity (18.86%) increased by 28.9% and 42.8% compared with the case of \(d/s\) = 0.078 in this section, respectively. With the transport inside the AITD, the wakes moved downstream in a clockwise direction (as viewed in the flow direction), as shown by the red and black straight arrow lines in Figure 8, because of the tangential velocity due to the rotation of the sweeping rod. Meanwhile, they were also diffusing continuously, as shown by their increasing width and decreasing peak turbulence intensity in Sections B2-B6 of Figure 8. In comparison, the high turbulence intensity of the wake when \(d/s\) was large often meant faster energy exchange with the surrounding fluid, which made its diffusion speed and dissipation rate greater than the cases with a small \(d/s\). Compared with the case of \(d/s\) = 0.078, the wake width was increased by 36.4% and the reduction of peak turbulence intensity was increased by 2.5% in Section B6 of Figure 8 when \(d/s\) = 0.122. When \(d/s\) \(\geq\) 0.10, the adjacent swept wakes in the AITD diffused to contact each other at a certain position upstream of Section B5, the interaction between wakes occurred, and the dissipation of their turbulence intensity was further enhanced. This behavior was another reason for the increasing dissipation rate of the wake peak turbulence intensity in the case of a large \(d/s\). Figure 7: Comparison between experimental and numerical results. Figure 9 shows the distribution of the time-averaged static pressure coefficient on the hub and shroud of the AITD for different \(d/s\) values. The sweeping wake, which blocked the effective flow area of the AITD as a low-energy fluid mass, not only led to a decrease in total pressure but also caused an increase in velocity (constant flow) by blocking the flow area, which inevitably resulted in a decrease in static pressure in the AITD. With the increase in \(d/s\), the increasing width and intensity of the sweeping wakes further enhanced their blockage effect, resulting in a greater reduction in the static pressure coefficient. As shown in Figure 9, the static pressure coefficients on the AITD shroud and hub decreased with increasing \(d/s\) in all cases, which supported the above inference. However, the different surfaces in the AITD had different responses to the wake blocking effect: (1) At the first bend of the AITD (\(x/C_{x}\) = 0-1.8), the static pressure coefficient on the hub decreased more than that of the shroud with increasing \(d/s\), which reduced the radial pressure gradient from the hub to the shroud. The differential Cp\({}_{\rm s}\) was 0.62, 0.61 and 0.57 at \(x/C_{x}\) = 0.4 when \(d/s\) was 0.078, 0.10 and 0.122, respectively. (2) In contrast, at the second bend of the AITD (\(x/C_{x}\) = 2.0-3.0), the static pressure coefficient on the shroud decreased more than that of the hub with increasing \(d/s\), which reduced the radial pressure gradient from the shroud to the hub. The differential Cp\({}_{\rm s}\) was 0.84, 0.84 and 0.83 at \(x/C_{x}\) = 2.8 when the \(d/s\) values were 0.078, 0.10 and 0.122, respectively. Under the different sweeping wake conditions, the change in the radial pressure gradient in the AITD would affect the development of internal secondary flow and the vortex migration and interaction process, which will be analyzed in detail below. Figure 8: Circumferential distribution of turbulence intensity at the midspan of different passages inside the AITD. Figure 9: Time-averaged wall static pressure coefficient on the hub and shroud of the AITD.