Delay of Dynamic Stall Using Pulsed Air-Jet Vortex Generators

Green, R. B.; Prince, Simon; Wang, Y.; Khodagolian, Vahik; Coton, F. N.

doi:10.2514/1.j056560

Cited by 3 publications

(2 citation statements)

References 18 publications

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“…On the one hand, this was because they faced a rapidly changing working environment, where passive control struggled to consistently maintain high control efficiency. The active flow control methods included air blowing control [43][44][45][46][47], a synthetic jet [48], and plasma control technology [49][50][51][52][53][54], among others. The blowing control technology involved injecting high-momentum gas into the boundary layer to reduce the flow instability [55], suppress flow separation, and consequently delay dynamic stall.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation on the Evolution Process of Different Vortex Structures and Distributed Blowing Control for Dynamic Stall Suppression of Rotor Airfoils

Li,

Yi,

et al. 2024

Actuators

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The influencing characteristic for the evolution mechanism of a dynamic stall vortex structure and distributed blowing control on rotor airfoils was investigated. Based on the moving-embedded grid method, the finite volume scheme, and Roe’s FDS scheme, a simulation method for the unsteady flow field of a pitch-oscillating airfoil was established. The flow field of the NACA63-218 airfoil was calculated using Reynolds-averaged Navier–Stokes equations. The evolution processes of different vortex structures during dynamic stall and the principal controlled vortex mechanism affecting aerodynamic nonlinearity were analyzed based on the pressure contours Cp and Q of the flow field structure and the spatiotemporal evolution characteristics of the wall pressure distribution. The research indicated that dynamic stall vortices (DSVs) and shear layer vortices (SLVs) were the major sources of the increase in aerodynamic coefficients and the onset of nonlinear hysteresis. Building upon these findings, the concept of distributed blowing control for DSVs and shear layer vortices (SLVs) was introduced. A comparative analysis was conducted to assess the control effectiveness of dynamic stall with different blowing locations and blowing coefficients. The results indicated that distributed blowing control effectively inhibited the formation of DSVs and reduced the intensity of SLVs. This led to a significant decrease in the peak values of the drag and pitch moment coefficients and the disappearance of secondary peaks in the aerodynamic coefficients. Furthermore, an optimal blowing coefficient existed. When the suction coefficient Cμ exceeded 0.03, the effectiveness of the blowing control no longer showed a significant improvement. Finally, with a specific focus on the crucial motion parameters in dynamic stall, the characteristics of dynamic stall controlled by air blowing were investigated. The results showed that distributed air blowing control significantly reduced the peak pitching moment coefficient and drag coefficient. The peak pitching moment coefficient was reduced by 72%, the peak drag coefficient was reduced by 70%, and the lift coefficient hysteresis loop area decreased by 46%. Distributed blowing jet control effectively suppressed the dynamic stall characteristics of the airfoil, making the unsteady load changes gentler.

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Section: Introductionmentioning

confidence: 99%

Numerical Investigation on the Evolution Process of Different Vortex Structures and Distributed Blowing Control for Dynamic Stall Suppression of Rotor Airfoils

Li,

Yi,

et al. 2024

Actuators

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“…In general, flow control approaches can be divided into active flow control and passive flow control, according to whether there is energy injection. Common passive flow control methods include leading edge rods [9], variable droop leading edges [10], vortex generators [11], and trailing edge flaps [12], and active flow control methods include air jets [13], dielectric barrier discharge (DBD) actuators [14][15][16][17] and co-flow jets [18].…”

Section: Introductionmentioning

confidence: 99%

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

Zeyang

Gao

et al. 2023

Plasma Sci. Technol.

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To alleviate the performance deterioration caused by dynamic stall of the wind turbine airfoil, the flow control by microsecond-pulsed dielectric barrier discharge (MP-DBD) actuator on the dynamic stall of a periodically pitching NACA0012 airfoil was investigated experimentally. The unsteady pressure measurements with high temporal accuracy were employed in this study, and the unsteady characteristics of the boundary layer were investigated by wavelet packet analysis and the moving root mean square (RMS) method based on the acquired pressure. The experimental Mach number was Ma =0.2, and the chord-based Reynolds number was Re = 870000. The dimensionless actuation frequencies F+ were chosen to be 0.5, 1, 2, and 3, respectively. For the light dynamic regime, the MP-DBD plasma actuator plays the role of suppressing flow separation from the trial edge and accelerating the flow reattachment due to the high momentum freestream flow being entrained into the boundary layer. Meanwhile, actuation effects were promoted with the increasing dimensionless actuation frequency F+. The control effects of the deep dynamic stall were to delay the onset and reduce the strength of the dynamic stall vortex (DSV), due to the accumulating vorticity near the leading edge being removed by the induced coherent vortex structures. The laminar fluctuation and K-H (Kelvin-Helmholtz) instabilities of transition and relaminarization were also mitigated by the MP-DBD actuation, and the alleviated K-H rolls lead to the delay of the transition onset and earlier laminar reattachment, which improved the hysteresis effect of the dynamic stall. For the controlled cases of F+ = 2, and F+ = 3, the laminar fluctuation was replaced by relatively low frequency band disturbances corresponding to the harmonic responses of the MP-DBD actuation frequency.

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Numerical simulation of dynamic stall flow control using a multi-dielectric barrier discharge plasma actuation strategy

Zeyang

Gao

et al. 2022

Physics of Plasmas

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To alleviate the deterioration in wind turbine performance caused by dynamic stall, the flow control of a pitching NACA0012 airfoil is investigated through numerical simulation of an alternating current dielectric barrier discharge (AC-DBD) plasma actuator at a Reynolds number Re = 135 000. To avoid the harmonic oscillations of aerodynamic force caused by unsteady DBD actuation, this work focuses on improving the control potential for steady actuation. The control mechanisms of actuators at various positions are investigated using five groups of actuators mounted at 0%, 3%, 10%, 45%, and 80% chord lengths c above the upper surface of an airfoil. The actuator at 80% c performs more efficiently in terms of lift enhancement in the initial upstroke and the final downstroke. The actuator at 0% c suppresses the growth of the leading-edge vortex and maintains the suction of the dynamic stall vortex (DSV). After the shedding of the DSV, it suppresses the secondary separation to delay the onset of dynamic stall. At the flow reattachment stage, the actuators at 3% c and 10% c accelerate the boundary layer reattachment by momentum injection. From these results, a multi-DBD control strategy is proposed. The scheme selects the optimal actuator in operation at a certain stage of dynamic stall and takes advantage of actuators at different positions to enhance the average and maximum aerodynamic force, delay the onset of dynamic stall, accelerate flow reattachment, and avoid excessive energy consumption.

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Delay of Dynamic Stall Using Pulsed Air-Jet Vortex Generators

Cited by 3 publications

References 18 publications

Numerical Investigation on the Evolution Process of Different Vortex Structures and Distributed Blowing Control for Dynamic Stall Suppression of Rotor Airfoils

Numerical Investigation on the Evolution Process of Different Vortex Structures and Distributed Blowing Control for Dynamic Stall Suppression of Rotor Airfoils

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

Numerical simulation of dynamic stall flow control using a multi-dielectric barrier discharge plasma actuation strategy

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