Computational Study on Dynamic Stall and Flow Control in a Pitching Airfoil

2021 ◽  
pp. 1-10
Author(s):  
Patibandla B. L. V. Ramana ◽  
Akshoy Ranjan Paul ◽  
Anuj Jain ◽  
Kazuo Matsuura
Keyword(s):  
Flow Control ◽  
Computational Study ◽  
Dynamic Stall ◽  
Pitching Airfoil

Computational Study of Inlet Active Flow Control

2007 ◽  
Author(s):  
Sonya T. Smith ◽  
Angela Scribben ◽  
Matthew Goettke
Keyword(s):  
Flow Control ◽  
Computational Study ◽  
Active Flow Control ◽  
Active Flow

Active Flow Control of Dynamic Stall by Means of Continuous Jet Flow at Reynolds Number of 1 × 106

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Mehran Tadjfar ◽  
Ehsan Asgari
Keyword(s):  
Reynolds Number ◽  
Flow Control ◽  
Pressure Difference ◽  
Active Flow Control ◽  
Velocity Ratio ◽  
Dynamic Stall ◽  
Hysteresis Curve ◽  
Small Range ◽  
Active Flow ◽  
The Impact

We have studied the influence of a tangential blowing jet in dynamic stall of a NACA0012 airfoil at Reynolds number of 1 × 106, for active flow control (AFC) purposes. The airfoil was oscillating between angles of attack (AOA) of 5 and 25 deg about its quarter-chord with a sinusoidal motion. We have utilized computational fluid dynamics to investigate the impact of jet location and jet velocity ratio on the aerodynamic coefficients. We have placed the jet location upstream of the counter-clockwise (CCW) vortex which was formed during the upstroke motion near the leading-edge; we have also considered several other locations nearby to perform sensitivity analysis. Our results showed that placing the jet slot within a very small range upstream of the CCW vortex had tremendous effects on both lift and drag, such that maximum drag was reduced by 80%. There was another unique observation: placing the jet at separation point led to an inverse behavior of drag hysteresis curve in upstroke and downstroke motions. Drag in downstroke motion was significantly lower than upstroke motion, whereas in uncontrolled case the converse was true. Lift was significantly enhanced during both upstroke and downstroke motions. By investigating the pressure coefficients, it was found that flow control had altered the distribution of pressure over the airfoil upper surface. It caused a reduction in pressure difference between upper and lower surfaces in the rear part, while substantially increased pressure difference in the front part of the airfoil.

Experimental investigation of dynamic stall flow control for wind turbine airfoils using a plasma actuator

Energy ◽  
2019 ◽  
Vol 185 ◽  
pp. 90-101 ◽  
Author(s):  
Li Guoqiang ◽  
Zhang Weiguo ◽  
Jiang Yubiao ◽  
Yang Pengyu
Keyword(s):  
Experimental Investigation ◽  
Flow Control ◽  
Wind Turbine ◽  
Plasma Actuator ◽  
Dynamic Stall ◽  
Turbine Airfoils

Power extraction from stall-induced oscillations of an airfoil

2017 ◽  
Vol 29 (7) ◽  
pp. 1407-1417 ◽  
Author(s):  
Flávio D Marques ◽  
Daniel A Pereira ◽  
Mohamed Y Zakaria ◽  
Muhammad R Hajj
Keyword(s):  
Electrical Power ◽  
Average Power ◽  
Dynamic Stall ◽  
Experimental Conditions ◽  
Aerodynamic Efficiency ◽  
Pitching Airfoil ◽  
Power Extraction ◽  
Naca0012 Airfoil ◽  
Structural Nonlinearities ◽  
Air Speed

Aerodynamic and structural nonlinearities of aeroelastic systems control different aspects of their limit cycle oscillations and bifurcations. One strong nonlinear unsteady aerodynamic effect that results in self-induced oscillations of airfoils is the dynamic stall. So, the concept of power extraction from stall-induced oscillations of a pitching airfoil is investigated. Experiments are performed to explore and enhance the conversion of the oscillations of a NACA0012 airfoil that is restrained elastically in pitching to electrical power. Wind tunnel tests are performed on an airfoil model connected to a DC electric motor to harvest the energy. The effects of varying the position of the axle, which defines the elastic axis, are investigated. Bifurcation diagrams as the air speed is increased and average power estimates for different experimental conditions are used to analyze the power extraction features. The results show an aerodynamic efficiency of about 40% indicating that an airfoil oscillating under the effects of dynamic stall is an adequate platform for energy harvesting.

New combinational active control strategy for improving aerodynamic characteristics of airfoil and rotor

2019 ◽  
Vol 234 (4) ◽  
pp. 977-996
Author(s):  
Yi-yang Ma ◽  
Qi-jun Zhao ◽  
Guo-qing Zhao
Keyword(s):  
Flow Control ◽  
Control Strategy ◽  
Active Flow Control ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Synthetic Jet ◽  
Dynamic Stall ◽  
Trailing Edge ◽  
Trailing Edge Flap ◽  
Cfd Method

In order to improve the aerodynamic characteristics of rotor, a new active flow control strategy by combining a synthetic jet actuator and a variable droop leading-edge or a trailing-edge flap has been proposed. Their control effects are numerically investigated by computational fluid dynamics (CFD) method. The validated results indicate that variable droop leading-edge and synthetic jet can suppress the formation of dynamic stall vortex and delay flow separation over rotor airfoil. Compared with the baseline state, Cdmax and Cmmax are significantly reduced. Furthermore, parametric analyses on dynamic stall control of airfoil by the combinational method are conducted, and it indicates that the aerodynamic characteristics of the oscillating rotor airfoil can be significantly improved when the non-dimensional frequency ( k*) of variable droop leading-edge is about 1.0. At last, simulations are conducted for the flow control of rotor by the combinational method. The numerical results indicate that large droop angle of variable droop leading-edge can better reduce the torque coefficient of rotor and the trailing-edge flap has the capability of increasing the thrust of rotor. Also, the synthetic jet could further improve the aerodynamic characteristics of rotor.

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