Super-Lift Coefficient of Active Flow Control Airfoil: What is the Limit?

2017 ◽  
Author(s):  
Yunchao Yang ◽  
Gecheng Zha
Keyword(s):  
Flow Control ◽  
Active Flow Control ◽  
Lift Coefficient ◽  
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.

Active Flow Control of Flapping Airfoil Using Openfoam

2019 ◽  
Vol 36 (3) ◽  
pp. 361-372
Author(s):  
Vedulla Manoj Kumar ◽  
Chin-Cheng Wang
Keyword(s):  
Flow Control ◽  
Active Flow Control ◽  
Lift Coefficient ◽  
Unsteady Motion ◽  
Plasma Actuators ◽  
Beneficial Effects ◽  
Plasma Actuation ◽  
Reduced Frequency ◽  
Flapping Airfoil ◽  
Active Flow

ABSTRACTThe concept of the fixed wing Micro Air Vehicles (MAVs) has received increasing interest over the past few decades, with the principal aim of carrying out the surveillance missions. The design of the flapping wing MAVs still is in infancy stage. On the other hand, there has been increasing interest over the flow control using plasma actuators in worldwide. The aim of this research is to study the flow control of a flapping airfoil with and without plasma actuation in OpenFOAM. The OpenFOAM CFD platform has been used to develop our own plasma solver. For the plasma induced turbulence in the flow regime, k-ε turbulence model was adopted to address the interaction between plasma and fluid flows. For the plasma-fluid interaction, we use reduced-order modelling to solve the plasma induced electric force. A two dimensional NACA0012 flapping airfoil without plasma actuation study has been benchmarked with previous published literature. We have not only focused on the active flow control but also analyzed the important parameter reduced frequency at different values, those are 0.1, 0.05 and 0.025. Reduced frequency (κ) is very important parameter of an airfoil in the unsteady motion. Our major contribution is testing the several reduced frequencies with the plasma actuation. The positive and beneficial effects of the plasma actuator for all cases have been observed. From the observed results, the flapping with plasma actuation at reduced frequency of 0.1 showed the 14.285 percent lift improvement and the 16.19 percent drag reduction than the flapping without plasma actuation at the respective dynamic stall angles. The maximum lift coefficient is increased with the increase in reduced frequency. In overall, plasma actuators are effective in the flow control of a flapping airfoil. In future, the combination of the flapping with plasma actuators will be a promising application to boast the maneuverability of MAVs.

Experimental Investigation on Stall Separation Control on NACA0015 Airfoil by Steady Plasma Aerodynamic Actuation

2012 ◽  
Vol 516-517 ◽  
pp. 726-730 ◽  
Author(s):  
Min Sun ◽  
Bo Yang ◽  
Jian Min Li ◽  
Ming Kai Lei
Keyword(s):  
Experimental Investigation ◽  
Flow Control ◽  
Free Stream ◽  
Active Flow Control ◽  
Lift Coefficient ◽  
Actuation Voltage ◽  
Control Effectiveness ◽  
Plasma Flow Control ◽  
Stall Angle ◽  
Active Flow

Experimental investigation was performed to study the influence law of the free-stream speed, angle of attack and actuation voltage on the control effectiveness of NACA0015 airfoil stall separation suppression by steady plasma aerodynamic actuation. It is found that plasma actuation can effectively suppress flow separation on the airfoil at free-stream speeds in the range from 20 m/s up to 65 m/s. When the speed is 25m/s, the stall angle will be delayed by 3°, lift coefficient will increase and drag coefficient will decrease by 10.4% and 28.9% respectively. Moreover, Experimental results indicate that the threshold voltage increases with the increasing free-stream speed and attack angle. Meanwhile, both of smoke flow visualization and flow control experiments were carried out, conclusions show that the direction of induce flow has little effect on plasma flow control effectiveness, which means that momentum transferring is not the basic cause of active flow control of plasma aerodynamic actuation.

Active Flow Control over the Car

2011 ◽  
Vol 110-116 ◽  
pp. 2521-2528
Author(s):  
Deepesh Kumar Singh ◽  
Gautam Bandyopadhyay
Keyword(s):  
Flow Control ◽  
Aerodynamic Drag ◽  
Active Flow Control ◽  
Lift Coefficient ◽  
Boundary Layer Suction ◽  
Car Model ◽  
The Standard Model ◽  
Drag And Lift ◽  
Drag And Lift Coefficient ◽  
Active Flow

Active flow control methods are used to reduce the aerodynamic drag over a car model. Method of Boundary layer suction at the top rear and air injection at the back of the car are used as the active flow control tools to suppress the aerodynamic drag. The computational results obtained using the standard model for the car model are verified first against the practical results obtained by wind tunnel experimentation so as to obtain the range of turbulence. Then a parametric study on the effect of the drag and lift coefficient of the car with respect to the parameters governing the active flow control is done. The drag coefficient is reduced by 20.25% using this strategy with 19.4% increase in the lift coefficient.

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