Numerical Study of Aerodynamic Performance of Airfoils at Low Angles of Attack by Active Flow Control of Trailing Edge Vortices

2006 ◽  
Author(s):  
Jose Vadillo ◽  
Ramesh Agarwal
Keyword(s):  
Flow Control ◽  
Numerical Study ◽  
Active Flow Control ◽  
Aerodynamic Performance ◽  
Trailing Edge ◽  
Active Flow

Surface suction on aerofoil aerodynamic characteristics at transonic speeds

1998 ◽  
Vol 212 (5) ◽  
pp. 339-351 ◽  
Author(s):  
N Qin ◽  
Y Zhu ◽  
D I A Poll
Keyword(s):  
Flow Control ◽  
Numerical Study ◽  
Active Flow Control ◽  
Effective Means ◽  
Active Surface ◽  
Aerodynamic Characteristics ◽  
Aerodynamic Performance ◽  
Surface Suction ◽  
Lift And Drag ◽  
Active Flow

This paper presents a numerical study of the effects of an active flow control through surface suction on shock boundary layer interactions over transonic aerofoils. Two different aerofoils were studied. Firstly, for the purpose of validation, an NACA64A010 aerofoil with a trailing edge flap was investigated and the numerical results were compared with experimental data with and without suction for surface pressure distributions and lift and drag coefficients. Grid sensitivity has also been studied regarding the numerical accuracy. The second geometry was an RAE9647 aerofoil, which was designed for superior aerodynamic performance when applied to a helicopter rotor blade. An active surface was used to prevent or alleviate shock-induced separation. The suction strength and location were varied to determine the effect on aerodynamic performance and to provide an effective means of suppressing undesirable flow features. In both cases, increases in both lift and drag were observed when surface suction was applied. However, the benefit of suction appeared in the form of a substantial increase in the lift-drag ratio. It was also found that the shock location and strength are very sensitive to the suction location and strength. Two different mechanisms for active flow control over transonic aerofoils are discussed.

Closed-Loop Active Flow Control of the Wake of a Compressor Blade by Trailing-Edge Blowing

2015 ◽  
Author(s):  
Matthias Kiesner ◽  
Rudibert King
Keyword(s):  
Flow Control ◽  
Mass Flow ◽  
Closed Loop ◽  
Active Flow Control ◽  
Hammerstein Model ◽  
Robust Controller ◽  
Trailing Edge ◽  
Velocity Deficit ◽  
Reference Velocity ◽  
Active Flow

This paper presents a closed-loop active flow control strategy to reduce the velocity deficit of the wake of a compressor stator blade. The unsteady stator-rotor interaction, caused by the incoming stator wakes, generates fast changes of the rotor blade loading, affecting the stability and the performance of the overall compressor. Negative effects will be seen likewise when unsteady combustion concepts, such as a pulsed detonation, produce upstream disturbances. Furthermore, the periodic unsteady flow leads to additional undesired effects such as noise and blade vibrations. A controlled reliable manipulation of the stator wake is a way to handle these issues. Therefore, investigations on wake manipulation with trailing-edge blowing were carried out on a new low-speed cascade test rig. Detailed information about the wake profile is obtained by five-hole probe measurements in a plane downstream of the cascade for the natural and the actuated flow at a Reynolds number of 6×105. These measurements show a significant reduction of the wake velocity deficit for the investigated actuator geometry with an injection mass flow of less than 1% of the passage mass flow. Based on these results a position in the wake was chosen which is representative for the actuation impact on the velocity deficit. There, a hot-wire-probe measurement serves as the controlled variable. A family of linear dynamic black-box models was identified from experimental data to account for nonlinear and unmodelled effects. Static nonlinearitiy was compensated for by a Hammerstein model to reduce the model uncertainty and get a higher controller performance. To handle off-design conditions, a robust controller working in a range of Reynolds numbers from 5×105 to 7×105 was synthesized. The task of the controller is to rapidly regulate the controlled variable to a reference velocity by changing the blowing amplitude. The synthesized robust controller was successfully tested in closed-loop experiments with good results in reference tracking for pulse series up to 20 Hz. This translates into a much higher frequency when scaled to the dimension of a real machine.

Trailing edge noise reduction of wind turbine blades by active flow control

Wind Energy ◽  
2014 ◽  
Vol 18 (5) ◽  
pp. 909-923 ◽  
Author(s):  
Alexander Wolf ◽  
Thorsten Lutz ◽  
Werner Würz ◽  
Ewald Krämer ◽  
Oksana Stalnov ◽  
...  
Keyword(s):  
Flow Control ◽  
Wind Turbine ◽  
Noise Reduction ◽  
Active Flow Control ◽  
Turbine Blades ◽  
Wind Turbine Blades ◽  
Trailing Edge ◽  
Trailing Edge Noise ◽  
Active Flow

scholarly journals Numerical study on the steady suction active flow control of hydrofoil in the profile of the blended-wing-body underwater glider

2021 ◽  
Vol 39 (4) ◽  
pp. 801-809
Author(s):  
Xiaoxu Du ◽  
Lianying Zhang
Keyword(s):  
Flow Control ◽  
Numerical Study ◽  
Active Flow Control ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Hydrodynamic Performance ◽  
Flow State ◽  
Underwater Glider ◽  
Blended Wing Body ◽  
Active Flow

The hydrodynamic performance of the blended-wing-body underwater glider can be improved by opening a hole on the surface and applying the steady suction active flow control. In order to explore the influence law and mechanism of the steady suction active flow control on the lift and drag performance of the hydrofoil, which is the profile of the blended-wing-body underwater glider, based on the computational fluid dynamics (CFD) method and SST k-ω turbulence model, the steady suction active flow control of hydrofoil under different conditions is studied, which include three suction factors: suction angle, suction position and suction ratio, as well as three different flow states: no stall, critical stall and over stall. Then the influence mechanism in over stall flow state is further analyzed. The results show that the flow separation state of NACA0015 hydrofoil can be effectively restrained and the flow field distribution around it can be improved by a reasonable steady suction, so as to the lift-drag performance of NACA0015 hydrofoil is improved. The effect of increasing lift and reducing drag of steady suction is best at 90° suction angle and symmetrical about 90° suction angle, and it is better when the steady suction position is closer to the leading edge of the hydrofoil. In addition, with the increase of the suction ratio, the influence of steady suction on the lift coefficient and drag coefficient of hydrofoil is greater.

Increasing the Aerodynamic Performance of a Formula Student Race Car by Means of Active Flow Control

2019 ◽  
Author(s):  
Ben Steinfurth ◽  
Arne Berthold ◽  
Steffen Feldhus ◽  
Frank Haucke ◽  
Julien Weiss
Keyword(s):  
Flow Control ◽  
Active Flow Control ◽  
Aerodynamic Performance ◽  
Race Car ◽  
Active Flow
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