scholarly journals Aerodynamic Analysis of Active Trailing-Edge Flaps and Passive Surface Roughness on NACA 4412 Airfoil

2020 ◽  
Vol 943 ◽  
pp. 012036
Author(s):  
Thanesh A/L Manickam ◽  
Sukanta Roy
Keyword(s):  
Surface Roughness ◽  
Trailing Edge ◽  
Aerodynamic Analysis ◽  
Trailing Edge Flaps

Adaptive Neurocontrol of Simulated Rotor Vibrations Using Trailing Edge Flaps

1999 ◽  
Vol 10 (11) ◽  
pp. 855-871
Author(s):  
MICHAEL G. SPENCER ◽  
ROBERT M. SANNER ◽  
INDERJIT CHOPRA
Keyword(s):  
Trailing Edge ◽  
Trailing Edge Flaps

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.

scholarly journals An investigation of unsteady 3D effects on trailing edge flaps

2016 ◽  
Author(s):  
Eva Jost ◽  
Annette Fischer ◽  
Galih Bangga ◽  
Thorsten Lutz ◽  
Ewald Krämer
Keyword(s):  
Trailing Edge ◽  
Trailing Vortices ◽  
Trailing Edge Flaps ◽  
Negative Effect ◽  
3D Effects ◽  
Computational Fluid Dynamics Cfd ◽  
Trailing Edge Flap ◽  
The Impact ◽  
2D Airfoil ◽  
High Influence

Abstract. The present study investigates the impact of unsteady and viscous 3D aerodynamic effects on a wind turbine blade with trailing edge flap by means of Computational Fluid Dynamics (CFD). Harmonic oscillations are simulated on the DTU 10 MW rotor with a morphing flap of 10 % chord extent ranging from 70 % to 80 % blade radius. The deflection frequency is varied in the range between 1 p and 6 p. To quantify 3D effects, rotor simulations are compared to 2D airfoil computations and the 2D theory by Theodorsen. A significant influence of trailing and shed vortex structures has been found which leads to an amplitude reduction and hysteresis of the lift response in the flap section with regard to the deflection signal. For the 3D rotor results greater amplitude reductions and a less pronounced hysteresis is observed compared to the 2D airfoil case. Blade sections neighboring the flap experience however an opposing impact and hence partly compensate the negative effect of trailing vortices in the flap section in respect to integral loads. The comparison to steady flap deflections at the 3D rotor revealed the high influence of dynamic inflow effects.

scholarly journals Pressure Based Lift Estimation and its Application to Feedforward Load Control employing Trailing Edge Flaps

2020 ◽  
Author(s):  
Sirko Bartholomay ◽  
Tom T. B. Wester ◽  
Sebastian Perez-Becker ◽  
Simon Konze ◽  
Christian Menzel ◽  
...  
Keyword(s):  
Surface Pressure ◽  
Feedforward Control ◽  
Force Balance ◽  
Estimation Methods ◽  
Load Control ◽  
Trailing Edge ◽  
Trailing Edge Flaps ◽  
Feedforward Controller ◽  
Trailing Edge Flap ◽  
C 30

Abstract. This experimental load control study presents results of an active trailing edge flap feedforward controller for wind turbine applications. The controller input is derived from pressure based lift estimation methods that rely either on a quasi-steady method, based on a three-hole probe, or on an unsteady method that is based on three selected surface pressure ports. Furthermore, a standard feedback controller, based on force balance measurements, is compared to the feedforward control. A Clark-Y airfoil is employed for the wing that is equipped with a trailing edge flap of x/c = 30 % chordwise extension. Inflow disturbances are created by a two-dimensional active grid. The Reynolds number is Re = 290,000 and reduced frequencies of k = 0.07 up to k = 0.32 are analyzed. Within the first part of the paper, the lift estimation methods are compared. The surface pressure based method shows generally more accurate results whereas the three-hole probe estimate overpredicts the lift amplitudes with increasing frequencies. Nonetheless, employing the latter as input to the feedforward controller is more promising as a beneficial phase lead is introduced by this method. A successful load alleviation was achieved up to reduced frequencies of k = 0.192.

Surface roughness effect on rotor broadband noise

2018 ◽  
Vol 17 (4-5) ◽  
pp. 438-466 ◽  
Author(s):  
Baofeng Cheng ◽  
Yiqiang Han ◽  
Kenneth S Brentner ◽  
Jose Palacios ◽  
Philip J Morris ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Surface Roughness ◽  
Turbulent Boundary Layer ◽  
Layer Thickness ◽  
Turbulence Intensity ◽  
Boundary Layer Thickness ◽  
Broadband Noise ◽  
Ice Accretion ◽  
Trailing Edge ◽  
Trailing Edge Noise

The change of helicopter rotor broadband noise due to different surface roughness during ice accretion is investigated. Comprehensive rotor broadband noise measurements are carried out on rotor blades with different roughness sizes and rotation speeds in two facilities: the Adverse Environment Rotor Test Stand facility at The Pennsylvania State University, and the University of Maryland Acoustic Chamber. In both facilities, the measured high-frequency broadband noise increases significantly with increasing surface roughness height. Rotor broadband noise source identification is conducted and the broadband noise related to ice accretion is thought to be turbulent boundary layer-trailing edge noise. Theory suggests turbulent boundary layer-trailing edge noise scales with Mach number to the fifth power, which is also observed in the experimental data confirming that the dominant broadband noise mechanism during ice accretion is trailing edge noise. A correlation between the ice-induced surface roughness and the broadband noise level is developed. The correlation is strong, which can be used as an ice accretion early detection tool for helicopters, as well as to quantify the ice-induced roughness at the early stage of rotor ice accretion. The trailing edge noise theories developed by Ffowcs Williams and Hall, and Howe both identify two important parameters: boundary layer thickness and turbulence intensity. Numerical studies of two-dimensional airfoils with different ice-induced surface roughness heights are conducted to investigate the extent that surface roughness impacts the boundary layer thickness and turbulence intensity (and ultimately the turbulent boundary layer-trailing edge noise). The results show that boundary layer thickness and turbulence intensity at the trailing edge increase with the increased roughness height. Using Howe’s trailing edge noise model, the increased sound pressure level of the trailing edge noise due to the increased displacement thickness and normalized integrated turbulence intensity are 6.2 and 1.6 dB for large and small accreted ice roughness heights, respectively. The estimated increased sound pressure level values agree reasonably well with the experimental results, which are 5.8 and 2.6 dB for large and small roughness height, respectively.

The Dassault Mirage G

1969 ◽  
Vol 73 (708) ◽  
pp. 1027-1028
Author(s):  
Henri Deplante
Keyword(s):  
Leading Edge ◽  
Variable Geometry ◽  
Relative Thickness ◽  
Trailing Edge ◽  
High Lift ◽  
Profound Knowledge ◽  
Subsonic Speed ◽  
Trailing Edge Flaps ◽  
Leading Edge Slats

The interest of wings with variable sweepback springs directly from pure commonsense and appeals to no profound knowledge of aerodynamics for its justification. To realise the advantage of variable geometry, it is enough to know that only a wing of small relative thickness is capable of good performance at supersonic speeds and that by increasing the sweepback from 20° to 70° the thickness of a wing is divided by about 2. In the advanced position, the wing offers its full span to the airstream and with high-lift devices in action (leading-edge slats and trailing-edge flaps combined), the aeroplane can develop the considerable lift necessary for take-off and landing as well as for break-through and for slow approach. Wings still advanced but slats, flaps and undercarriage retracted, the aeroplane is in excellent maximum fineness condition for protracted cruising at subsonic speed or for a long wait. As soon as transonic (Mach No of more than 0-8) or supersonic speeds are in question, the wings are progressively folded back.

Sign in / Sign up

Export Citation Format

Share Document