## 3 Results at Constant Angle of Attack
On the basis of these results, the traveling wave  
Figure 7: Time history of unsteady lift \(C_{\text{l}}\), drag \(C_{\text{d}}\) and mid-chord moment coefficient \(C_{\text{m}_{v/2}}\) at constant angle of attack of two degrees; Re \(\sim\)350,000.  
mode simulations discussed in the following section are performed with a larger body force on the suction side and a smaller one on the pressure side. Figure 9 shows the pressure coefficient distribution for the clean blade, compared to the configuration with PS and SS actuation, respectively. Consistently with the results achieved in terms of flow field, PS actuation yields a clearly visible negative peak in the plasma region. The opposite occurs for the SS actuation. The most influential effect induced by the actuation can be seen by looking at the pressure distribution upstream the actuation, up to the leading edge. Indeed, SS actuation yields an overall modification of the pressure distribution, characterized by a covered area that is smaller compared to the clean configuration. This causes an overall attenuation of blade loading. The opposite occurs with PS actuation. This latter induces a modification of the pressure distribution, such that the area covered by the curve is significantly larger relative to the clean configuration. As a consequence, an increase in blade loading is expected. It is worth remarking that these results are in qualitative agreement with the assessments of Refs. [16; 17; 18; 19; 20], where the same effects were obtained with a mechanical L-tab deflected  
Figure 8: Trailing edge detail of velocity magnitude, normalized by the freestream velocity, and of z-vorticity magnitude, normalized by the chord/freestream velocity ratio, for the clean cascade and with PS/SS actuation; Re \(\sim\)350,000; \(\alpha=2\) degrees. downward or upward, installed on a helicopter blade section. Additionally, the computed flow fields are qualitatively consistent with the Particle Image Velocimetry measurements of [PERSON] et al. [21] on a low-speed fixed wing section with PS plasma actuation opposite to the freestream direction. Figure 10 shows an histogram of the aerodynamic loads, computed on the clean, PS- and SS-actuated configurations, at angles of attack ranging from 0 to 12 degrees. Namely, the lift coefficient C\({}_{\text{I}}\), the drag coefficient C\({}_{\text{d}}\) and the mid-chord moment coefficient C\({}_{\text{mc/2}}\) are reported. As anticipated, actuation yields a modification of the effective camber, opposite for PS and SS plasma, alongside a chord-wise shift of the Kutta condition downstream of the trailing edge. Both PS and SS actuations provide lift and pitching moment modifications, which are also quantitatively comparable to those of Refs. [16; 17; 18; 19; 20], achieved with a mechanical Gurney flap. In particular, PS actuation allows for increasing the lift coefficient without changing the blade angle of attack, and with no significant drawbacks in terms of drag. The moment coefficient--nose-down positive--increases in magnitude, relative to the non-actuated counterpart. That is, PS actuation has a stabilizing effect on the mean airfoil torsion (see [46]). On the other hand, SS actuation yields effects that are comparable to those exhibited by upward deflections of control surfaces. Namely, lift is reduced compared to the clean configuration, with potential benefits in counteracting stall phenomena [19]. A reduction of the pitching moment, relative to the clean configuration, is observed. Again, no major effects are encountered in terms of drag rise. The affection of the actuation on the pitching moment is regarded as particularly important for this work. Within this framework, it is worth remarking that the behavior of pitching moment according to PS/SS actuation is consistent with the results of several works in literature, dealing with mechanical trailing edge control surfaces, e.g., Refs. [19; 47; 48].