The recent advances in nanoscience
DBD-VGs were able to control rotating stall, whereby steady forcing at Up/U′ ≈ 0.1, Cμ ≈ 0.02% reduced the torque due to aerodynamic drag by 11–24%. This should be accompanied by a similar increase in lift to yield a significant increase in turbine power output. No direct power measurements were possible due to the complexities in instrumenting rotating high voltage components for the MLN 9708 actuators. Nevertheless, the DBD-VGs appeared to postpone trailing edge separation over the outboard part of the blade in a manner very similar to the 2D case. Entrainment into the DBD plays a key role here, along with re-energizing the boundary layer through streamwise vortical mixing. At the same time, DBD-VGs appeared to shift the separation zone closer to the hub. Though this enhanced the separation near the hub, it greatly improves the flow over the mid and outer blades which are, after all, most important for generating power. This is believed to be because the DBD-VGs induce a radial flow towards the hub which counteracts the Coriolis-induced flow towards the tip in the separation zone. This hypothesis is reinforced by the fact that DBD-CFs had very little effect on rotating stall, and these actuators only produced a body force in the chord-wise direction. Thus a radial body force component was a necessary requirement for flow control in this experiment. Counteracting the Coriolis-induced radial flow in the separation zone is recommended for smart rotor control using dielectric barrier discharge plasma actuators.