Улучшение подъемных характеристик крыла со сверхкритическим профилем при использовании модулированного импульсного струйного актуатора

In this experimental investigation, a pulse flow control system on a high-lift device of a wing with a NASA SC(2)-0714 airfoil within the Reynolds number range of the take-off and landing phases, is proposed. In this study, an innovative method of signal modulation has been used in order to simultaneously exploit the benefits of both low and high excitation frequencies in one actuator driving signal that are known to be effective in separation control. It is observed that the lift and drag coefficients are improved due to the use of modulated pulse jets compared to the simple pulse jet.

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

Symmetry ◽

10.3390/sym12050828 ◽

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.

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Effect of an internal nonlinear rotational dissipative element on vortex shedding and vortex-induced vibration of a sprung circular cylinder

Journal of Fluid Mechanics ◽

10.1017/jfm.2017.504 ◽

2017 ◽

Vol 828 ◽

pp. 196-235 ◽

Cited By ~ 15

Author(s):

Ravi Kumar R. Tumkur ◽

Arne J. Pearlstein ◽

Arif Masud ◽

Oleg V. Gendelman ◽

Antoine B. Blanchard ◽

...

Keyword(s):

Circular Cylinder ◽

Nonlinear Energy Sink ◽

Stream Velocity ◽

Rectilinear Motion ◽

Mean Flow ◽

Number Range ◽

Vortex Induced Vibration ◽

Concomitant Reduction ◽

Fixed Radius ◽

Lift And Drag

We computationally investigate coupling of a nonlinear rotational dissipative element to a sprung circular cylinder allowed to undergo transverse vortex-induced vibration (VIV) in an incompressible flow. The dissipative element is a ‘nonlinear energy sink’ (NES), consisting of a mass rotating at fixed radius about the cylinder axis and a linear viscous damper that dissipates energy from the motion of the rotating mass. We consider the Reynolds number range $20\leqslant Re\leqslant 120$, with $Re$ based on cylinder diameter and free-stream velocity, and the cylinder restricted to rectilinear motion transverse to the mean flow. Interaction of this NES with the flow is mediated by the cylinder, whose rectilinear motion is mechanically linked to rotational motion of the NES mass through nonlinear inertial coupling. The rotational NES provides significant ‘passive’ suppression of VIV. Beyond suppression however, the rotational NES gives rise to a range of qualitatively new behaviours not found in transverse VIV of a sprung cylinder without an NES, or one with a ‘rectilinear NES’, considered previously. Specifically, the NES can either stabilize or destabilize the steady, symmetric, motionless-cylinder solution and can induce conditions under which suppression of VIV (and concomitant reduction in lift and drag) is accompanied by a greatly elongated region of attached vorticity in the wake, as well as conditions in which the cylinder motion and flow are temporally chaotic at relatively low $Re$.

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