Compressible Dynamic Stall Control: Comparison of Two Approaches

Chandrasekhara, M. S.; Wilder, Michael C.; Carr, L. W.

doi:10.2514/2.2812

Cited by 10 publications

(5 citation statements)

References 15 publications

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“…height) to obtain detailed information about the NACA 0012 airfoil operating under conditions that produce dynamic stall [7]. The Reynolds number was around 6x10 5 and the average dimensionless pitching frequency (k) was 0.1. The airfoil was constrained so that sinusoidal oscillations (α = 15.05° + 10.25° Sin ωt) in pitch could be imposed.…”

Section: Experimental Setup and Instrumentationmentioning

confidence: 99%

“…Unsteady separating flows over pitching airfoils have therefore been extensively investigated [1]. Attempts have been made to manipulate the flow using various types of active flow-control devices, such as, steady blowing, periodic zero-mass-flux wall blowing and mechanically forced deformable leading edge nose [2,3,4,5]. Exter-nally driven flexible walls form another important mode of flow control.…”

Section: Introductionmentioning

confidence: 99%

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An Interesting Phenomenon Observed in the Wind Tunnel

Lal Mangla,

K Sinha

2023

joast

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An extremely high lift was observed over a pitching NACA 0012 airfoil model placed in a low speed subsonic wind tunnel. A leading edge mounted flexible actuator was electrically excited at a given frequency. The excitation power was around 1 W. A 1.5 HP motor, used for pitching the airfoil slowed down and finally stopped. The motor regained its motion when the actuator excitation was stopped. The high lift generated is backed by the pressure measurements made along the central chord axis of the airfoil model. The phenomenon was repeated many times.

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Section: Experimental Setup and Instrumentationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An Interesting Phenomenon Observed in the Wind Tunnel

Lal Mangla,

K Sinha

2023

joast

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“…The study reported in Ref. 8 addresses this using a variable shape leading-edge in compressible dynamic stall, and this is an interesting candidate approach. However, the leading-edge environment on a rotor is severe, as evidenced by the use of erosion strips along most operational rotors, and flow control actuation in this region may be difficult to engineer.…”

Section: Nomenclature Amentioning

confidence: 99%

Trailing-edge flap flow control for dynamic stall

Green

Gillies²,

Wang³

2011

Aeronaut. j.

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Results of a series of oscillatory dynamic stall tests of a rotor aerofoil fitted with a pulsed, trailing-edge flap are presented. Flap deflection amplitude, motion profile, duration and starting phase were investigated to assess the potential of the flap for mitigating the adverse effects of dynamic stall, which is one of the limiting factors for rotor blades on the retreating side of a helicopter rotor. The tests were a continuation of the investigations by Ref. 1 who used a computational fluid dynamics method on a symmetric NACA section, and our results broadly confirm their conclusions by experimental test, using a modern rotor section. The results presented in this paper also confirm the observations from experimental work by Refs 2 and 3, which were undertaken at lower Reynolds number and with a larger flap. In the present study, the flap mitigates the high negative pitching moment and negative pitch damping seen in dynamic stall by strong suction being generated over the aerofoil lower surface, and it is the modification to the lower surface shape by the flap that creates this effect. The dynamic stall vortex acts to enhance the lower surface suction, and careful flap phasing and flap motion profile shaping can make the control more effective.

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“…Unsteady separating flows over pitching airfoils have therefore been extensively investigated [1] and details of the underlying physics unraveled, especially at low Reynolds numbers. Using this knowledge attempts have been made to manipulate the flow using various types of active flow-control devices, such as, steady blowing, periodic zero-mass-flux wall blowing and mechanically forced deformable leading edge nose [2,3,4,5,6,7,8]. Externally driven flexible walls form another important mode of flow control.…”

Section: Introductionmentioning

confidence: 99%

Controlling Dynamic Stall With an Active Flexible Wall

Mangla,

Sinha

2023

joast

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A low energy active flexible wall transducer has been used to interact with unsteady separating boundary layers over a pitching NACA 0012 airfoil, at a Mach Number of 0.1, Reynolds Number around 6 E 05 and reduced frequencies around 0.1. The transducer consisted of an array of thin strip shaped high and low electrodes covered with an aluminized Mylar membrane. An electric excitation was given to two adjacent strips generating vibrations of the membrane of around 0.01 μm amplitude over the actuated strips. The pressures were measured along the central chord axis using a pressure scanner. The electric excitation of the transducer at a frequency corresponding to Strouhal Number (based on strip spacing and local free stream velocity) of approximately 1 delayed the onset of dynamic stall by 2°. The maximum actuation power consumption was 1 W for 30 cm of actuated length in the span wise direction.

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Compressible Dynamic Stall Control: Comparison of Two Approaches

Cited by 10 publications

References 15 publications

An Interesting Phenomenon Observed in the Wind Tunnel

An Interesting Phenomenon Observed in the Wind Tunnel

Trailing-edge flap flow control for dynamic stall

Controlling Dynamic Stall With an Active Flexible Wall

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