Dynamic stall control over an airfoil by NS-DBD actuation*

Abstract

The wind tunnel test was conducted with an NACA 0012 airfoil to explore the flow control effects on airfoil dynamic stall by NS-DBD plasma actuation. Firstly, light and deep dynamic stall states were set, based on the static stall characteristics of airfoil at a Reynolds number of 5.8 × 105. Then, the flow control effect of NS-DBD on dynamic stall was studied and the influence law of three typical reduced frequencies (k = 0.05, k = 0.05, and k = 0.15) was examined at various dimensionless actuation frequencies (F + = 1, F + = 2, and F + = 3). For both light and deep dynamic stall states, NS-DBD had almost no effect on upstroke. However, the lift coefficients on downstroke were increased significantly and the flow control effect at F + = 1 is the best. The flow control effect of the light stall state is more obvious than that of deep stall state under the same actuation conditions. For the same stall state, with the reduced frequency increasing, the control effect became worse. Based on the in being principles of flow separation control by NS-DBD, the mechanism of dynamic stall control was discussed and the influence of reduced frequency on the dynamic flow control was analyzed. Different from the static airfoil flow separation control, the separated angle of leading-edge shear layer for the airfoil in dynamic stall state is larger and flow control with dynamic oscillation is more difficult. The separated angle is closely related to the effective angle of attack, so the effect of dynamic stall control is greatly dependent on the history of angles of attack.

Experimental study on dynamic stall control based on AC-DBD actuation

“…As we know, for a static airfoil's separation control, the actuation's control effect extensively depends on the airfoil's α, and the stall can only be delayed by 2-3 degrees [9]. This means that the plasma actuation has a range of capabilities, and it has no effect at the small angle of attack where the leading edge does not separate and the high α is much larger than the stall α.…”

“…During the past 10 years, the dielectric barrier discharge (DBD) plasma actuation has been extensively researched due to its advantages of simple construction, no moving components, broad frequency band and fast response. Recently, nanosecond dielectric barrier discharge (NS-DBD) has attracted attention in the field of dynamic stall control by virtue of its stronger disturbance ability to the flow field [8,9], while alternating current dielectric barrier discharge (AC-DBD) is the most widely used actuation method. Compared with NS-DBD, AC-DBD has smaller electromagnetic interference.…”

“…The discharge parameter testing system consists of a highvoltage probe, current probe and digital oscilloscope to measure the discharge voltage and current of the actuator [9]. Figure 3 shows the voltage(V )-current(I) signals collected when the actuation peak-to-peak voltage V p-p =9 kV, the pulsed actuation frequency f p =200 Hz, and the duty ratio DC=50%.…”

Experimental investigation of dynamic stall flow control using a microsecond-pulsed plasma actuator

“…In the work of Singhal et al [31], the aerodynamic hysteresis effect and DSV strength were reduced by nanosecond DBD plasma (NS-DBD) actuators, and the DSV was completely eliminated by sufficiently high actuation frequency. Yang et al [32] also used NS-DBD to explore the flow control effects on airfoil dynamic stall at a Reynolds number of 5.8×10 5 ; DBD actuation performed more effectively in the downstroke stage, and the control effect gradually became weaker with a reduced frequency increase. Li and Yi [33] applied a large eddy simulation numerical calculation to verify the plasma unsteady actuation mechanism on dynamic stall, the results showed that the separation vortices are broken and dissipated by the DBD actuation, and led to a strong nonlinear oscillation of aerodynamic force caused by the interaction between dynamic vortex structures with plasma actuation.…”

Flow Separation Control of Nacelle Inlets in Crosswinds by Dielectric Barrier Discharge Plasma Actuation

“…It has attracted wide attention in recent years and is widely used in biomedicine [12][13][14][15][16], environmental purification [17][18][19][20], catalytic technology [21][22][23][24], material handling [25][26][27], flow control, and other fields. Surface Dielectric Barrier Discharge (SDBD) [28] which has the advantages of easy adhesion, rapid response, and adjustable parameters, has been widely used in the fields of stall control [29][30][31][32][33][34], boundary layer rotation [35][36][37][38][39][40], lift enhancement [41][42][43], anti-icing [44][45][46][47][48] and other flow separation control applications. Surface dielectric barrier discharge is classified as Alternating Current Dielectric Barrier Discharge (AC-DBD), Microsecond Dielectric Barrier Discharge (µS-DBD), and Nanosecond Dielectric Barrier Discharge (NS-DBD), of which AC-DBD and NS-DBD are more widely used than µS-DBD.…”