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As with other types of wind turbines, the ducted wind turbine has a bright future. On the other hand, flow separation has a consistent effect on this type of turbine, resulting in aerodynamic losses and load fluctuations. As a result, flow control systems for ducted wind turbines are critical for improving aerodynamic performance. Additionally, in this technological age, noise pollution has developed into a serious problem that must be minimized and controlled to the greatest extent feasible. This research investigates the impact of a plasma actuator as an active control approach on the flow dynamics on the blades using a finite volume code. To decrease computing costs, the URANS model and mesh adaptive methods are applied. The numerical results are confirmed by comparing them to a previously collected experimental dataset. The flow dynamics and noise emission of a micro dielectric-barrier-discharge plasma actuator were examined under the impact of discontinuous pulsing. This actuator was fitted in three distinct places at the beginning point of separation in the blade without using the ducted wind turbine’s control approach. The results indicated that positioning the actuator near the blades’ tip improves aerodynamic performance. Additionally, when the plasma actuator’s power is raised, the vortex cancellation is maximized. The results indicated that the DBD actuator generated a considerable portion of reverse flow, in this case in the opposite direction to the tip flow. The reverse flow was used to alter the pressure gradient in the tip gap area, thereby eliminating the vortex. Also, using the plasma actuator reduces the ducted wind turbine’s noise output by cutting down on the wake zone and vortices, which are the main sources of noise.

A pair of plasma actuators with horseshoe shape is proposed for dynamic manipulation of forebody aerodynamic load at high angles of attack. Preliminary wind tunnel pressure measurements show that asymmetric force over a conical forebody with semi-apex angle 10° can be manipulated by activating the plasma actuator mounted on one side of the cone tip. Further work is suggested.

The structures of a flow field induced by a plasma actuator were investigated experimentally in quiescent air using high-speed Particle Image Velocimetry (PIV) technology. The motivation behind was to figure out the flow control mechanism of the plasma technique. A symmetrical Dielectric Barrier Discharge (DBD) plasma actuator was mounted on the suction side of the SC (2)-0714 supercritical airfoil. The results demonstrated that the plasma jet had some coherent structures in the separated shear layer and these structures were linked to a dominant frequency of $f_0$ = 39 Hz when the peak-to-peak voltage of plasma actuator was 9.8 kV. The high speed PIV measurement of the induced airflow suggested that the plasma actuator could excite the flow instabilities which lead to production of the roll-up vortex. Analysis of transient results indicated that the roll-up vortices had the process of formation, movement, merging and breakdown. This could promote the entrainment effect of plasma actuator between the outside airflow and boundary layer flow, which is very important for flow control applications.

Alternating current dielectric barrier discharge plasma actuators driven by steady and unsteady mode were experimentally optimized in a static atmosphere. The purpose of this optimization is to enhance the effective controllability of flow control. Electrical properties were evaluated using the measured voltage, current and power consumption data. The dielectric barrier with different materials was tested and the aerodynamic characteristics were identified by particle image velocimetry and electronic force balance. Meanwhile, the duty-cycle technique was applied to operate the actuator in unsteady mode. The dynamic characteristics of induced flow were analyzed by processing the results with the phase-locked method. The development of induced flow structure at different frequencies was compared. Results showed that the plasma actuator with 4 mm-thick Teflon dielectric barrier induced the maximum force and velocity of 75 mN/m and 5.6 m/s, respectively. The discharge frequency has little effect on the control authority at the kilohertz level. The dimensionless area of the induced flow is about $6.5\times 1$ under steady actuation. The phase-locked results confirm that the scale and strength of the induced vortex vary with the duty-cycle frequencies. The effectiveness of unsteady flow control can be explained as the promotion of the boundary layer and the mainstream.

Mechanism of flow separation control by the micro or small devices such as plasma actuators is discussed based on a series of computations of low speed flows over an NACA 0015 airfoil with devices attached near the leading edge. The DBD plasma actuator is shown to be very effective for controlling flow separation at a Reynolds number of 6.3 × 10⁴. Flow attachment phenomenon induced by these devices is strongly related to the turbulent transition but the study reveals that it is not the only factor for the flow separation control. Analysis of the phase-average flow structures reveals that there exist remarkable structures in the flow near the airfoil surface, which characterizes the actuator-oriented flows to reduce flow separation.