Investigation On Flow Control Over Wings Using DBD Plasma Actuator

The application of flow control on aircraft can effectively improve the aerodynamic characteristics performance with drag reducing and lift increasing. Dielectric barrier discharge plasma flow control is a new active control technology by means of controlling the separation of boundary layer nearby aircraft which increases the lift-drag ratio and stall angle of attack, thereby decreasing the take-off and landing distance. In this dissertation plasma effects on flow field around the wing are investigated with deploying dielectric barrier discharge plasma actuator on wing surface. Furthermore, the regulation of plasma perturbation on airfoil is concluded and the plasma control mechanism on boundary layer separation is researched. The content of this dissertation can be listed as follows.Firstly the numerical simulation method of DBD flow control is built based on the research project; secondly, comprehensive experimental methods and scheme of wind tunnel force test, PIV test and continuous laser sheet method are established; next, the experimental facilities are induced, as well as other considerations related, which lay the foundation for the next study.In the experiment, NACA23018 airfoil and one kind of high-lift configuration are chosen as research object. The DBD actuators are deployed at different places on foil surface, with excitation voltage, excitation frequency, free stream speed, electrode span, and electrode length as variables to investigate and evaluate the control effects. To probe into the couple effects, single and multiple actuators are respectively taken into experiment to compare their impacts on flow control. The study found that plasma perturbation imposed nearby the flow separation point can achieve best control effect and also showed that control effect can get stronger along with increasing excitation voltage and frequency. Comparing with single actuator, multiply actuators can induce stronger control effect because of coupling.Surface tuft method is used to demonstrate the flow pattern around foil in experiment. It shows that the silk thread on upper foil stick to surface closely after plasma perturbation is exerted, which means that flow separation diminish. To capture the overall process of the flow field with plasma perturbation, flow records, shot by continuous laser sheet, indicates that a stable jet flow is induced upon the electrode, which interacts with flow in boundary layer, strengthening the mixing inside and outside boundary layer. This effect increases the ability to resistance against boundary layer separation and leads to a smaller separation zone upon the foil which all does good to drag reducing and lift increasing. Application of PIV flow visualization technology also recorded the changing process of flow passing the foil under the effect of plasma and indicated the mechanism of DBD plasma control on boundary layer separation. This can offer reference to application of DBD plasma control on high lift complex configuration.Finally, perturbation parameter regulations of DBD plasma control in flow are concluded, as well as flow control mechanism. In conclusion, in this dissertation, an effective DBD plasma control method on flow is obtained and the computation and experiment results can be useful in flow control of high lift complex configuration in new concept of lift increasing and drag decreasing.