Three Flow Features behind the Flow Control Authority of DBD Plasma Actuator: Result of High-Fidelity Simulations and the Related Experiments

Kozo Fujii

doi:10.3390/app8040546

Abstract

Both computational and experimental studies are conducted for understanding of the flow separation control mechanism of a DBD (dielectric barrier discharge) plasma actuator. Low speed flows over an airfoil are considered. A DBD plasma actuator is attached near the leading edge of an airfoil and the mechanism of flow control of this small device is discussed. The DBD plasma actuator, especially in burst mode, is shown to be very effective for controlling flow separation at Reynolds number of 6.3 × 104, when applied to the flows at an angle of attack higher than the stall. The analysis reveals that the flow structure includes three remarkable features that provide good authority for flow separation control with the appropriate actuator parameters. With proper setting of the actuator parameters to enhance the effective flow features for the application, good flow control can be achieved. Based on the analysis, guidelines for the effective use of DBD plasma actuators are proposed. A DBD plasma actuator is also applied to the flows under cruise conditions. With the DBD plasma actuator attached, a simple airfoil turns out to show higher lift-to-drag ratio than a well-designed airfoil.

Highlights

Flow separation is a common phenomenon in many industrial applications, including transportation vehicles and rotating machinery
We have focused on Topic (3), because we believe that understanding of the reason that burst mode works better than continuous mode for the same applied voltage would lead to finding the key features of the DBD plasma actuator
The mechanism of flow control by the DBD plasma actuator is discussed based on a series of computations and experiments for low-speed flows over airfoils with these devices attached near the leading edge

Summary

Introduction

Flow separation is a common phenomenon in many industrial applications, including transportation vehicles and rotating machinery. The plasma actuator induces a weak jet-like flow (with a maximum speed of a few meters per second in general) in a small region near the airfoil surface as a result of ion motion in the plasma due to dielectric barrier discharge phenomenon induced by the high alternating current (AC) voltage applied on the electrodes. Both the experimental and computational analysis showed that this device is very effective for flow separation control at the Reynolds numbers less than 105 [5,6,7,8,9,10,11].

Methods

Results

Conclusion