## 3 Results and Discussion
### Effect of Wake on the Integrated LPT-GV
In the tip region of the LPT-GV, the passage vortices (marked by 'PV' in Section C3 of Figure 16) entrained a large amount of low momentum fluid in the boundary layer of the end wall, resulting in the boundary layer of Section C3 being thinner than that of Section C2 in all cases. Comparing these passage vortices in different cases, the PV area in Section C3 decreased with increasing \(d/s\). This result was obtained because the boundary layer thickness of the end wall and radial pressure gradient, which are two important factors for the formation of passage vortices, decreased with increasing \(d/s\). Similarly, the strength and range of PV3 split from the passage vortices downstream of Section C3 and decreased with increasing \(d/s\). Unlike PV3, the influence range of the residual passage vortex increased with \(d/s\), as shown by the yellow contour marked by 'PV1' in Figure 10:2 This result was obtained mainly because many low momentum fluids were in the region around the shroud, which could be entrained by PV1, due to the dissipation of the residual wake vortices (as shown in  
Figure 10:3 Vortices in the integrated LPT-GV passage when \(d/s=0.078\). Section B6 of Figure 10) when \(d/s\) was large. This result also showed that the influence of wake on the vortices in the LPT-GV's tip region had an obvious two-sidedness: (1) it could weaken the passage vortices by reducing the radial pressure gradient; (2) the low-momentum fluid could enhance the passage vortices in the LPT-GVs' tip region due to its own strong dissipation. In the midspan of the LPT-GV, the boundary layer of the suction surface continuously thickened from Section C3 to Section C5 in Figure 16 because of the inverse pressure gradient (as shown in Figure 16). Moreover, with increasing \(d/s\), the boundary layer thickness of the suction surface increased in the same axial section. This result was obtained because the wake could trigger the earlier transition of the boundary layer with increasing \(d/s\), which increased the growth time of the turbulent boundary layer under an inverse pressure gradient. At the root of the LPT-GV with increasing \(d/s\), the decreasing radial pressure gradient, as mentioned above, also weakens the passage vortices in this region (as shown by 'PV4' in Figure 16), which is conducive to reducing the total pressure loss in the corresponding regions. Figure 10:4 Total pressure coefficient contour of the integrated LPT-GV passages. Figure 17 shows the radial distribution of the pitchwise mass-averaged total pressure coefficient at the integrated AITD outlet. From the general trend, the total pressure coefficient decreased with increasing \(d/s\), but the mechanism of flow loss differed between regions: (1) Near the hub (h/H! 0.1), the wake dissipated rapidly in all cases and was exhausted before reaching the inlet of LPT-GV, so the loss in this region was hardly affected by the sweeping wake, as shown by the coincident total pressure coefficient curves of this region in Figure 10:5 (2) In the middle region (h/H = 0.2-0.7), the loss mainly came from wake dissipation and boundary layer separation. Although the sweeping wake could further inhibit the time and space range of separation bubbles when \(d/s\) was large, the aerodynamic income was still insufficient to compensate for the total pressure loss caused by the wake dissipation. Therefore, the total pressure coefficient in this region decreased with increasing \(d/s\). (3) Near the shroud (h/H! 0.7), the loss mainly came from the passage vortex and the wake mixing. Based on the above conclusions, strong residual wake vortices were still in this region at the inlet of the LPT-GV, which can bring total pressure gain by suppressing the passage vortex and separation bubble, and this aerodynamic profit was significantly greater than that in the middle region, so the total pressure coefficient in this region was higher than that in the middle region.