usually the flow behavior is laminar, which is important for control of the flow [2].Methods to flow separation control include active and passive techniques which are based on energy expenditure and controlled by command. Passive separation control techniques generally constitute geometric changes such as vortex generator, slotted flaps/slats, etc. These control elements are effective if the aircraft is operating in a flight regime that is in their design envelope. However, in off-design conditions, passive control elements can have detrimental effects that are often manifested in the form of increased drag [3]. Active separation control techniques have benefits of passive techniques without their disadvantage in off-design conditions. Also, these techniques have the potential to be implemented in a feedback system that can create more benefits in flight efficiency and maneuverability [3].Dielectric barrier discharge (DBD) plasma actuator is one of the active flow control devices that have been successfully used in aerodynamic flow control applications. Thus, considerable researches have been carried out on DBD plasma actuators over the past decade [4]. The examples of aerodynamic flow control applications by DBD plasma actuators include separation control in leading edge [5, 6], trailing edge [3, 7], bluff bodies [8], low pressure turbine blade [9, 10], axial compressor [11], flow control over a hump [12], Stabilizing a laminar boundary layer [13, 14], bluff body induced sound control [15], airfoil lift increasing [16], etc. Special characteristics of DBD plasma actuator over traditional flow control devices include reduction in size, weight and drag, increasing reliability, inexpensiveness, wide frequency bandwidth, rapid on-off capability, no moving parts, low energy consumption, and increasing stealth.The actuator consists of two asymmetrical metal electrodes separated by a dielectric layer, normally kapton, or Abstract The body force effects of plasma origin on the flow over a NACA 0015 airfoil are investigated by numerical simulation. The plasma actuator effect is estimated based on a phenomenological DBD plasma model coupled with 2-dimentional compressible Navier-Stokes equations. The equations are solved using an explicit finite volume method on unstructured grids. The responses of a separated flow field to the effects of a plasma actuator body force in various magnitudes and locations are presented. Also the effects of plasma region dimensions on the flow separation control are studied. It is found that the dimensions of plasma region, the magnitude of the body force, and the location of the plasma actuator all have significant impacts on the separation control.
In this paper, the effects of streamwise Nanosecond Dielectric Barrier Discharge (NS-DBD) actuators on Shock Wave/Boundary Layer Interaction (SWBLI) are investigated in a Mach 2.5 supersonic flow. In this regard, the numerical investigation of NS-DBD plasma actuator effects on unsteady supersonic flow passing a 14° shock wave generator is performed using simulation of Navier-Stokes equations for 3D-flow, unsteady, compressible, and k ‐ ω SST turbulent model. In order to evaluate plasma discharge capabilities, the effects of plasma discharge length on the flow behavior are studied by investigating the flow friction factor, the region of separation bubble formation, velocity, and temperature distribution fields in the SWBLI region. The numerical results showed that plasma discharge increased the temperature of the discharge region and boundary layer temperature in the vicinity of flow separation and consequently reduced the Mach number in the plasma discharge region. Plasma excitation to the separation bubbles shifted the separation region to the upstream around 6 mm, increased SWBLI height, and increased the angle of the separation shock wave. Besides, the investigations on the variations of pressure recovery coefficient illustrated that plasma discharge to the separation bubbles had no impressive effect and decreased pressure recovery coefficient. The numerical results showed that although the NS-DBD plasma actuator was not effective in reducing the separation area in SWBLI, they were capable of shifting the separation shock position upstream. This feature can be used to modify the structure of the shock wave in supersonic intakes in off-design conditions.
A numerical simulation method is employed to investigate the effects of the unsteady plasma body force over the stalled NACA 0015 airfoil at low Reynolds number flow conditions. The plasma body force created by a dielectric barrier discharge actuator is modeled with a phenomenological method for plasma simulation coupled with the compressible Navier-Stokes equations. The governing equations are solved using an efficient implicit finitevolume method. The responses of the separated flow field to the effects of an unsteady body force in various interpulses and duty cycles as well as different locations and magnitudes are studied. It is shown that the duty cycle and inter-pulse are key parameters for flow separation control. Additionally, it is concluded that the body force is able to attach the flow and can affect boundary layer grow that Mach number 0.1 and Reynolds number of 45000.
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