Numerical Analysis on Aerodynamic Force Generation of Biplane Counter-Flapping Flexible Airfoils

2009 ◽  
Vol 46 (5) ◽  
pp. 1785-1794 ◽  
Author(s):  
Jr-Ming Miao ◽  
Wei-Hsin Sun ◽  
Chang-Hsien Tai
Keyword(s):  
Numerical Analysis ◽  
Aerodynamic Force ◽  
Force Generation ◽  
Flexible Airfoils

Unsteady aerodynamic force generation by a model fruit fly wing in flapping motion

2002 ◽  
Vol 205 (1) ◽  
pp. 55-70 ◽  
Author(s):  
Mao Sun ◽  
Jian Tang
Keyword(s):  
Aerodynamic Force ◽  
Lift Coefficient ◽  
Unsteady Aerodynamics ◽  
Fruit Fly ◽  
Force Generation ◽  
Generation Process ◽  
Flapping Motion ◽  
Unsteady Aerodynamic ◽  
The Mean ◽  
Unsteady Aerodynamic Force

SUMMARY A computational fluid-dynamic analysis was conducted to study the unsteady aerodynamics of a model fruit fly wing. The wing performs an idealized flapping motion that emulates the wing motion of a fruit fly in normal hovering flight. The Navier–Stokes equations are solved numerically. The solution provides the flow and pressure fields, from which the aerodynamic forces and vorticity wake structure are obtained. Insights into the unsteady aerodynamic force generation process are gained from the force and flow-structure information. Considerable lift can be produced when the majority of the wing rotation is conducted near the end of a stroke or wing rotation precedes stroke reversal (rotation advanced), and the mean lift coefficient can be more than twice the quasi-steady value. Three mechanisms are responsible for the large lift: the rapid acceleration of the wing at the beginning of a stroke, the absence of stall during the stroke and the fast pitching-up rotation of the wing near the end of the stroke. When half the wing rotation is conducted near the end of a stroke and half at the beginning of the next stroke (symmetrical rotation), the lift at the beginning and near the end of a stroke becomes smaller because the effects of the first and third mechanisms above are reduced. The mean lift coefficient is smaller than that of the rotation-advanced case, but is still 80 % larger than the quasi-steady value. When the majority of the rotation is delayed until the beginning of the next stroke (rotation delayed), the lift at the beginning and near the end of a stroke becomes very small or even negative because the effect of the first mechanism above is cancelled and the third mechanism does not apply in this case. The mean lift coefficient is much smaller than in the other two cases.

Aerodynamic Force Generation in Hovering Flight in a Tiny Insect

AIAA Journal ◽  
2006 ◽  
Vol 44 (7) ◽  
pp. 1532-1540 ◽  
Author(s):  
Mao Sun ◽  
Xin Yu
Keyword(s):  
Aerodynamic Force ◽  
Force Generation ◽  
Hovering Flight

Sensitivity Analysis of the Factors Affecting Force Generation by Wing Flapping Motion

2013 ◽  
Author(s):  
Alok A. Rege ◽  
Brian H. Dennis ◽  
Kamesh Subbarao
Keyword(s):  
Sensitivity Analysis ◽  
Insect Flight ◽  
Aerodynamic Force ◽  
Force Production ◽  
Force Generation ◽  
Preliminary Review ◽  
Flow Solver ◽  
Factors Affecting ◽  
Flapping Motion ◽  
Wing Section

Insect flight comes with lot of intricacies that cannot be explained by conventional aerodynamics. Insects rely on a peculiar high frequency wing flapping mechanism to produce the aerodynamic forces required for sustainable flight. Broad study of this mechanism for producing forces is imperative to attain a reasonably accurate representation of these forces. In this research, sensitivity analysis is performed on the factors governing the aerodynamic force production due to flapping motion of a two-dimensional wing section of a Micro Air Vehicle (MAV). Published results obtained on a wing section of an MAV model by the authors in their previous work are used for preliminary review. The flapping path parameters are nondimensionalized and the moving mesh problem is solved in a numerical flow solver. A thorough sensitivity analysis is done to realize the effects of the flapping wing Reynolds number, Strouhal number, and the absolute angle of attack on the force generation.

scholarly journals Numerical Investigation of Galloping Instabilities in Z-Shaped Profiles

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Ignacio Gomez ◽  
Miguel Chavez ◽  
Gustavo Alonso ◽  
Eusebio Valero
Keyword(s):  
Numerical Analysis ◽  
Parametric Analysis ◽  
Aerodynamic Force ◽  
Flexible Structures ◽  
Turbulence Models ◽  
Standard Code ◽  
Airport Terminal ◽  
Stability Maps ◽  
Aeronautical Industry ◽  
Shading Devices

Aeroelastic effects are relatively common in the design of modern civil constructions such as office blocks, airport terminal buildings, and factories. Typical flexible structures exposed to the action of wind are shading devices, normally slats or louvers. A typical cross-section for such elements is a Z-shaped profile, made out of a central web and two-side wings. Galloping instabilities are often determined in practice using the Glauert-Den Hartog criterion. This criterion relies on accurate predictions of the dependence of the aerodynamic force coefficients with the angle of attack. The results of a parametric analysis based on a numerical analysis and performed on different Z-shaped louvers to determine translational galloping instability regions are presented in this paper. These numerical analysis results have been validated with a parametric analysis of Z-shaped profiles based on static wind tunnel tests. In order to perform this validation, the DLR TAU Code, which is a standard code within the European aeronautical industry, has been used. This study highlights the focus on the numerical prediction of the effect of galloping, which is shown in a visible way, through stability maps. Comparisons between numerical and experimental data are presented with respect to various meshes and turbulence models.

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