Circulation Control for High Lift and Drag Generation on STOL Aircraft

1975 ◽  
Vol 12 (5) ◽  
pp. 457-463 ◽  
Author(s):  
Robert J. Englar
Keyword(s):  
Circulation Control ◽  
High Lift ◽  
Lift And Drag

scholarly journals A Parametric Study of Trailing Edge Flap Implementation on Three Different Airfoils Through an Artificial Neuronal Network

Symmetry ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 828
Author(s):  
Igor Rodriguez-Eguia ◽  
Iñigo Errasti ◽  
Unai Fernandez-Gamiz ◽  
Jesús María Blanco ◽  
Ekaitz Zulueta ◽  
...  
Keyword(s):  
Aerodynamic Coefficients ◽  
Trailing Edge ◽  
High Lift ◽  
Trailing Edge Flaps ◽  
Artificial Neural Network Ann ◽  
Lift And Drag ◽  
Artificial Neuronal Network ◽  
Naca 0012 ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Trailing edge flaps (TEFs) are high-lift devices that generate changes in the lift and drag coefficients of an airfoil. A large number of 2D simulations are performed in this study, in order to measure these changes in aerodynamic coefficients and to analyze them for a given Reynolds number. Three different airfoils, namely NACA 0012, NACA 64(3)-618, and S810, are studied in relation to three combinations of the following parameters: angle of attack, flap angle (deflection), and flaplength. Results are in concordance with the aerodynamic results expected when studying a TEF on an airfoil, showing the effect exerted by the three parameters on both aerodynamic coefficients lift and drag. Depending on whether the airfoil flap is deployed on either the pressure zone or the suction zone, the lift-to-drag ratio, CL/CD, will increase or decrease, respectively. Besides, the use of a larger flap length will increase the higher values and decrease the lower values of the CL/CD ratio. In addition, an artificial neural network (ANN) based prediction model for aerodynamic forces was built through the results obtained from the research.

Circulation Control Span-Wise Blowing Location Optimization for a Helicopter Rotor Blade

2010 ◽  
Author(s):  
Alan M. Didion ◽  
Jonathan Kweder ◽  
Mary Ann Clarke ◽  
James E. Smith
Keyword(s):  
Stress Reduction ◽  
Rotor Blades ◽  
Helicopter Rotor ◽  
Base Line ◽  
Control Technology ◽  
Circulation Control ◽  
High Lift ◽  
Location Optimization ◽  
Helicopter Rotor Blades ◽  
Length Reduction

Circulation control technology has proven itself useful in the area of short take-off and landing (STOL) fixed wing aircraft by decreasing landing and takeoff distances, increasing maneuverability and lift at lower speeds. The application of circulation control technology to vertical take-off and landing (VTOL) rotorcraft could also prove quite beneficial. Successful adaptation to helicopter rotor blades is currently believed to yield benefits such as increased lift, increased payload capacity, increased maneuverability, reduction in rotor diameter and a reduction in noise. Above all, the addition of circulation control to rotorcraft as controlled by an on-board computer could provide the helicopter with pitch control as well as compensate for asymmetrical lift profiles from forward flight without need for a swashplate. There are an infinite number of blowing slot configurations, each with separate benefits and drawbacks. This study has identified three specific types of these configurations. The high lift configuration would be beneficial in instances where such power is needed for crew and cargo, little stress reduction is offered over the base line configuration. The stress reduction configuration on the other hand, however, offers little extra lift but much in the way of increased rotor lifespan and shorter rotor length. Finally, the middle balanced configuration offers a middle ground between the two extremes. With this configuration, the helicopter benefits in all categories of lift, stress reduction and blade length reduction.

Wind Tunnel Test of a Blended Wing Aircraft in Ground Effect With Active Flow Control

2016 ◽  
Author(s):  
Michael Mayo ◽  
Jonathan Carroll ◽  
Nicholas Motahari ◽  
Warren Lee ◽  
Robert Englar
Keyword(s):  
Wind Tunnel ◽  
Active Flow Control ◽  
Wind Tunnel Test ◽  
Ground Effect ◽  
Circulation Control ◽  
Wing Model ◽  
Subsonic Wind Tunnel ◽  
Test Methodology ◽  
Tunnel Floor ◽  
Lift And Drag

This paper describes the test methodology and results for a wind tunnel experiment featuring a blended wing aircraft in ground effect with built-in circulation control. A 82.55cm wingspan blended wing model was tested in a subsonic wind tunnel at velocities ranging from 18m/s – 49m/s and corresponding Reynolds numbers ranging from 130k – 350k. Pitch angle was held constant at 0 degrees and the height above the wind tunnel floor was modified to determine lift and drag modification due to ground effect. At a normalized height (y/bw) of 0.06, ground effect increased lift production by 24% and reduced drag by 22% when compared to a normalized height of 0.5. The addition of the circulation control significantly increased the lift production of the model at a cost of increased drag. At a normalized height of 0.031, the lift production increased by 200% at a blowing coefficient of 0.01, but the drag also increased by 72%, ultimately increasing L/D by 178%. Experimental results also suggest that ground effect and circulation control have a synergistic effect when used simultaneously. The effects of Reynolds number and circulation control slot height are also investigated.

Circulation Control Technology Applied to Propulsive High Lift Systems

1984 ◽  
Author(s):  
Robert J. Englar ◽  
James H. Nichols ◽  
Michael J. Harris ◽  
Joseph C. Eppel ◽  
Michael D. Shovlin
Keyword(s):  
Control Technology ◽  
Circulation Control ◽  
High Lift

High Lift Circulation Controlled Helicopter Blade

2006 ◽  
Author(s):  
Gerald M. Angle ◽  
Wade W. Huebsch ◽  
Zenovy S. Wowczuk ◽  
Jacky C. Prucz ◽  
James E. Smith
Keyword(s):  
Wind Tunnel ◽  
Lift Coefficient ◽  
Fold Increase ◽  
General Aviation ◽  
Circulation Control ◽  
Main Rotor ◽  
High Lift ◽  
Helicopter Blade ◽  
Drag Forces ◽  
Lift Capacity

Circulation control techniques have a long history of applications to fixed wing aircraft. General aviation has used circulation control to delay flow separation and increase the maximum lift coefficient achievable with a given airfoil. These techniques have been gradually expanded to other applications, such as ground vehicles, to reduce drag. Circulation control technology can, potentially, be applied also to each blade of the main rotor in a helicopter, in order to increase the lift capacity of the rotor. Applications of circulation control technologies to fixed wing aircraft have demonstrated the potential of a three-fold increase in the lift coefficient, as compared to a conventional airfoil. This finding would suggest that a rotorcraft equipped with circulation control of the main rotor blades could, conceivably, lift up a payload that is approximately three times heavier than the maximum lift capacity of the same helicopter without circulation control. Alternatively, circulation control could reduce the required rotor diameter by up to 48%, if the maximum lift capacity remains unaltered. A High Lift, Circulation Controlled Helicopter Blade will be undergoing initial testing in the subsonic wind tunnel facility at West Virginia University. Two-dimensional elliptic airfoil models with air blowing slots for circulation control will be used as specimens in these tests in order to determine the aerodynamic changes, especially in lift and drag forces, achievable with various blowing slot configurations. Based on the results of the wind tunnel testing, an improved, detailed design will be developed for the entire main rotor of a helicopter with circulation control.

Lift and Drag Characteristics of an Airfoil and Feedback Flow Control by Flap Actuators in the Low Reynolds Number Region

2015 ◽  
Author(s):  
Toshiki Mori ◽  
Masashi Yamaguchi ◽  
Kyoji Inaoka ◽  
Mamoru Senda
Keyword(s):  
Reynolds Number ◽  
Wind Speed ◽  
Unsteady Flow ◽  
Flow Control ◽  
Flow Condition ◽  
Low Reynolds Number ◽  
High Lift ◽  
Unsteady Flow Condition ◽  
Lift And Drag ◽  
Drag Ratio

The present paper describes the applicability of the flow control device, mini actuators attached on the leading edge of an airfoil, for the flow separation control under unsteady flow condition in the low Reynolds number region. Lift and drag have been measured for a wide variety of the wind speeds (Reynolds numbers) and the angles of attack. Then, effects of simple feedback flow control, where the time-dependent signal of the lift-drag ratio has been used as an input to detect the stall and served as a trigger to start the actuation, have been explored under the unsteady flow condition for evading the stall. For every Reynolds number from 30,000 to 80,000, the actuators worked quite well to delay the stall, increasing both in the lift and the stall angle of attack. Then, threshold value of the lift-drag ratio was determined to detect the stall. Effectiveness of the feedback control of the actuation was demonstrated under the condition of the wind speed decrease which would lead to the stall if no-actuation. Immediately after the velocity decrease, the decrease in the lift-drag ratio below the threshold were detected and the dynamic actuations were started, resulting in evading the stall and keeping high lift. The additional operation of the feedback, stopping the actuation when the lift-drag ratio showed lower than the second threshold, was revealed effective to keep the high lift force under the condition combined with the wind speed increase and decrease.

Airfoil Selection for a Straight Bladed Circulation Controlled Vertical Axis Wind Turbine

2009 ◽  
Author(s):  
Henry Z. Graham ◽  
Chad Panther ◽  
Meagan Hubbell ◽  
Jay P. Wilhelm ◽  
Gerald M. Angle ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Vertical Axis ◽  
Circulation Control ◽  
Vertical Axis Wind Turbine ◽  
Trailing Edge ◽  
Drag Coefficients ◽  
Initial Investigation ◽  
Edge Radius ◽  
Lift And Drag ◽  
Drag Ratio

A vertical axis wind turbine (VAWT) prototype is being developed at West Virginia University that utilizes circulation control to enhance its performance. An airfoil was chosen for this turbine based on its performance potential, and ability to incorporate circulation control. The selection process for the airfoil involved the consideration of camber, blade thickness, and trailing edge radius and the corresponding impact on the lift and drag coefficients. The airfoil showing the highest lift/drag ratio augmentation, compared to the corresponding unmodified airfoil was determined to be the most likely shape for use on the circulation control augmented vertical axis wind turbine. The airfoils selected for this initial investigation were the NACA0018, NACA2418, 18% thick elliptical, NACA0021, and the SNLA2150. The airfoils were compared using the computational fluid dynamics program FLUENT v.6.3.26 with a blowing coefficient of 1% [1]. The size of the trailing edge radius and the slot heights were varied based on past experimental data [2]. The three trailing edge radii and two blowing slot heights were investigated. The thickness of the airfoil impacts the circulation control performance [3], thus it was studied by scaling the NACA0018 to a 21% thickness and compared to an SNLA2150 airfoil. The airfoils’ lift and drag coefficients were compared to determine the most improved lift-drag ratio (L/D). When comparing the increases of the L/D due to circulation control, the NACA0018 and 2418 airfoils were found to outperform the elliptical airfoil; the NACA0018 performed slightly better than the 2418 when comparing the same ratio L/D. The results showed that the 21% thick airfoils produced a decreased L/D profile compared to the NACA0018 airfoils. Therefore, the NACA0018 was found to be the optimal airfoil based from this initial investigation due to an increased L/D compared to the other airfoils tested.

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