# Effect of NS-DBD Actuator Parameters on the Aerodynamic Performance of a Flap Lifting Device
## 1 Introduction  
As an important part of aircraft aerodynamic design, the flap lift device affects the take-off and landing performance of the aircraft and is closely related to flight safety, environmental protection, and economy. A mechanical flap lift device usually consists of multi-element airfoils arranged along the chordwise direction, including leading edge slats, leading edge flaps, and trailing edge flaps, etc. To meet the lift requirements for take-off and landing for large aircraft, the flap lift device even has as many as five sections, which makes the control mechanism overly complicated and increases the empty weight. Improving the lift efficiency of the flaps can reduce the number of flap sections and the additional mass. The dielectric barrier discharge (DBD) plasma actuator, which has received extensive attention in recent years, is able to control the local or global flow field efficiently by using slight and local disturbances [1; 2; 3]. Current research on DBD plasma actuators includes active control of separation flow [4], boundary layer transition control [5], pneumatic noise control [6], side force control for the revolution body [7], flight control [8], plasma propulsion [9], flow control in the engine [10], plasma sensors [11], etc. Compared with the AC-DBD (alternating-current dielectric barrier discharge) actuator, the NS-DBD (nanosecond dielectric barrier discharge) actuator has the advantages of small size, high discharge frequency and high controllable inlet velocity. Many scholars have also carried out research on the control of separation flow by using NS-DBD [12; 13; 14; 15]. [PERSON] et al. [16] used an NS-DBD actuator to increase the stall angle of attack of the aircraft during the wind tunnel test. From their viewpoint, at a large angle of attack, the actuator will generate a spanwise vortex, thus promoting the mixing of the flow and realizing control of the separation flow. [PERSON] et al. [17] carried out research to control the separation flow with a Mach number of incoming flow within the range of 0.05-0.85. The NS-DBD actuator can effectively realize the control of separation flow, lift increase, and drag reduction, as well as noise control at high Mach number. [PERSON] [18] reported the disturbance phenomenon of NS-DBD on the laminar boundary layer by numerical simulation. They believe that the main NS-DBD mechanism is the generation of a T-S disturbance wave, and thus the flow control mechanism of the NS-DBD may include a large-scale vortex, flow transitions, or other factors. [PERSON] et al. [19; 20; 21], from Ohio State University, used a plasma aerodynamic actuator to conduct a study on simplified flow control of the high lift device. The results show that the plasma actuator with millisecond pulses can effectively control the separation of the boundary layer of the trailing edge flap at a Reynolds number of \(2.4\times 10^{5}\)-\(7.5\times 10^{5}\). The plasma actuator with nanosecond pulses can only control the separation of the leading edge at a Reynolds number of \(7.5\times 10^{5}\)-\(1.00\times 10^{6}\), and it is difficult to control the separation of the trailing edge flap. [PERSON] et al. [22] studied the control ability of airfoil flow separation by a millisecond pulse plasma actuator. The results show that the plasma actuator can effectively restrain the flow separation at the leading edge of the airfoil and significantly improve the maximum lift coefficient of the airfoil. The effect is optimal when the flow control is applied simultaneously at the flap and the rear section of the main wing. In this condition, the maximum lift coefficient can be increased by approximately 30%. Two disturbances generated by NS-DBD are considered as potential mechanisms of flow control, the first is compression wave, the second is vortex structure [23; 24; 25]. [PERSON] et al.