## 3 Results and Discussion
The third point is that the incident leakage flow at the leading edge of the stator has a certain radial velocity, which together with the flow blockage induces spanwise migration, thus increasing the total pressure recovery coefficient at the middle of the stator and decreasing the total pressure recovery coefficient at the root of the stator, which is also reflected in Figure 6.  
Figure 7: Absolute Mach number distribution. It was previously suggested that the seal cavity leakage flow in the clearance may increase the loss at the root of the stator by changing the incidence and destroying the structure of the flow field, thus further affecting the pressure ratio and efficiency of the single stage compressor. Figures 9 and 10 confirm this hypothesis. Figure 9 is a sketch map of the spanwise distribution of the stator inlet incidence. It can be seen that with the increase in leakage flow rate, the incidence at the stator root (below 10% elevation) increases dramatically. This will lead to flow separation and further blockage of the blade passage, which in turn reduces the total pressure recovery coefficient. The high incidence characteristic of the stator root reflects that the flow capacity of the fluid in the root is weak and the axial momentum is small. However, with the increase in leakage flow rate, the overall decrease of the incidence above 20% elevation indicates that the leakage flow induces the flow to migrate toward the blade tip. Considering the fact that the amount of leakage flow is very small (no more than 0.20% of the mainstream), the spanwise migration is mainly caused by the blockage of the stator root flow induced by the leakage flow rather than the radial velocity of the leakage flow itself. Figure 10a,b show the distribution of fluid axial momentum divided by a unified reference value along the spanwise direction at the leading edge of the stator (downstream the left branch of the cavity) and at the 1.5 chord length downstream of the trailing edge of stator (downstream of the right branch of the cavity). As can be seen both from Figure 10a,b, the influence of leakage flow on the stator flow field is not limited to the hub region, but extends to the whole span. The axial momentum of the fluid decreases gradually with the increase of leakage flow at the stator root near the hub (below 10% span). The decrease in axial momentum reflects the increase in flow blockage. The flow blockage at the stator root causes the spanwise migration  
Figure 8: The radial distribution of the Stator’s total pressure recovery coefficient. Figure 9: The radial distribution of the Stator’s inlet incidence. of the flow, and the axial momentum in the middle span of the blade increases accordingly. The variation of inlet axial momentum to leakage flow in Figure 10a is consistent with that of incidence to leakage flow in Figure 9.  
In order to further verify the previous analysis, the corresponding spanwise static pressure ratio distribution of the stator was compared, as shown in Figure 11. As the leakage flow increases, the static pressure ratio of stator decreases in the whole span, and the reduction at the hub area is greater. This is consistent with the previous analysis. For a specific working condition, the spanwise position of the maximum static pressure rise increases with the increase in leakage flow rate, which reflects the spanwise migration caused by leakage flow. Figure 5:0 The radial distribution of axial momentum.