# Control of Corner Separation with Plasma Actuation in a High-Speed Compressor Cascade
## 3 Results
### Performances of Plasma Actuations in Suppressing the High-Speed Compressor Cascade Flow Separation  
2.1 Influences of Plasma Actuations on the High-Speed Compressor Cascade Flow Loss at Different Streamwise Planes  
Figure 8 shows the influences of plasma actuations on the high-speed compressor cascade flow loss at different streamwise planes. The \(\Delta\omega\) is obtained through the subtraction of the total pressure  
Figure 6: Flow structures within the high-speed compressor cascade corner separation and the development of the corresponding flow loss at an incidence angle of \(-4^{\circ}\). (**a**) Flow structures; (**b**) The development of flow loss. Figure 7: Flow structures within the high-speed compressor cascade corner separation and the development of the corresponding flow loss at an incidence angle of \(8^{\circ}\). (**a**) Flow structures; (**b**) The development of flow loss. loss coefficient of baseline condition from the plasma actuations, and the positive value in the figure indicates that the total pressure loss coefficient is reduced by the plasma actuations. The corresponding body force of each single plasma actuator in Figure 8 is confined to 837 mN/m. Based on Figures 5-8, it can be found that the influences of the suction surface and the endwall plasma actuations on the high-speed compressor cascade flow loss are closely related to the developments of the corner separations. When the high-speed compressor cascade corner separation occurs, the corresponding flow loss is obviously reduced by both the suction surface and the endwall plasma actuations. However, the locations and shapes of the regions where the suction surface and endwall plasma actuations reduce the flow loss are quite different. This phenomenon will be discussed later in this paper. According to Figure 8, the area of the regions where the high-speed compressor cascade flow loss is reduced by both the suction surface and the endwall plasma actuations keeps almost constant with the increase of incidence angles, and this is because the scope of the influences of plasma actuations is limited to the regions near solid walls. Since the strength and size of the high-speed compressor cascade corner separation increases dramatically with the increase of incidence angles, it can be concluded that the plasma actuation will impose a relatively smaller influence on the high-speed compressor  
Figure 8: Influences of plasma actuations on the high-speed compressor cascade flow loss at different streamwise planes. (**a**) With an incidence angle of \(-4^{\circ}\); (**b**) With an incidence angle of \(0^{\circ}\); (**c**) With an incidence angle of \(8^{\circ}\). cascade corner separations of large positive incidence angles than on that of smaller and negative incidence angles. As the high-speed compressor cascade corner separation is suppressed by the plasma actuations, the overall blockage of the cascade flow is reduced. As a result, the flow loss outside the high-speed compressor cascade corner separation region will be increased by the plasma actuations. Especially at negative incidence angles, as shown in Figure 8a, the original pressure side separations are obviously enhanced by both the suction surface and endwall plasma actuations. On the other hand, the endwall plasma actuation increases the flow loss near mid-span regions too, and this indicates that the endwall plasma actuation is incapable of suppressing the airfoil separations, which will be discussed later in this paper. 2.2 Influences of Plasma Actuations on the High-Speed Compressor Cascade Outlet Flow Loss, Static Pressure Rise and Blockage  
Figure 9 shows the influences of plasma actuations on the high-speed compressor cascade total pressure loss, static pressure rise, and blockage coefficients at different incidence angles.