scholarly journals Calculations of Unsteady Aerodynamic Forces of a Flat Plate at Torsional 1DOF Oscillation using CFD

2005 ◽  
Vol 30 (2) ◽  
pp. 37-46
Author(s):  
Hirokazu Hirano ◽  
Akira Maruoka ◽  
Yoshihiko Ohsa ◽  
Ryusuke Higashi
Keyword(s):  
Flat Plate ◽  
Aerodynamic Forces ◽  
Unsteady Aerodynamic

scholarly journals A Modified Van Der Pol Oscillator Model for the Unsteady Lift Produced by a Flapping Flat Plate for Different Positions of the Rotation Axis

Symmetry ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 88
Author(s):  
Chedhli Hafien ◽  
Abdellatif Messaoudi
Keyword(s):  
Flat Plate ◽  
Rotation Axis ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Van Der Pol Oscillator ◽  
Aerodynamic Forces ◽  
Van Der Pol ◽  
Unsteady Aerodynamic ◽  
Rotation Motion ◽  
Unsteady Lift

To understand the nonlinear interaction between unsteady aerodynamic forces and the kinematics of structures, we theoretically and numerically investigated the characteristics of lift coefficients produced by a flapping thin flat plate controlled by the rotation axis position. The flat plate was placed in a 2-D incompressible flow at a very low Reynolds number (Re = 300). We showed that the behavior of the unsteady aerodynamic forces suggests the existence of a limit cycle. In this context, we developed a Reduced Order Model (ROM) by resolving the modified van der Pol oscillator using the Taylor development method and computational fluid dynamics (CFD) solutions. A numerical solution was obtained by integrating the differential equation of the modified van der Pol oscillator using the fourth-order Runge–Kutta method (RK4). The model was validated by comparing this solution with the reformulated equation of the added mass lift coefficient. Using CFD and ROM solutions, we analyzed the dependency of the unsteady lift coefficient generation on the kinematics of the flapping flat plate. We showed that the evolution of the lift coefficient is influenced by the importance of the rotation motion of the Leading Edge (LE) or Trailing Edge (TE), according to the position of the rotation axis. Indeed, when the rotation axis is moved towards the LE, the maximum and the minimum values of the lift coefficient are proportional to the downward and upward motions respectively of the TE and the rotation axis. However, when the rotation axis is moved towards the TE, the maximum and the minimum values of the lift coefficient are proportional to the downward and upward motions respectively of the LE and the rotation axis.

Minimization of time-averaged and unsteady aerodynamic forces on a thick flat plate using synthetic jets

2015 ◽  
Vol 54 ◽  
pp. 522-535 ◽  
Author(s):  
Maher Ben Chiekh ◽  
Mohsen Ferchichi ◽  
Jean-Christophe Béra ◽  
Marc Michard
Keyword(s):  
Flat Plate ◽  
Synthetic Jets ◽  
Aerodynamic Forces ◽  
Unsteady Aerodynamic

Control of Unsteady Aerodynamic Forces

1990 ◽  
Author(s):  
Chih-Ming Ho ◽  
Ismet Gursul ◽  
Chiang Shih ◽  
Hank Lin ◽  
Mario Lee
Keyword(s):  
Aerodynamic Forces ◽  
Unsteady Aerodynamic

Unsteady Aerodynamic Forces Measured on a Fluttering Profile

2014 ◽  
Author(s):  
Igor Zolotarev ◽  
Václav Vlček ◽  
Jan Kozánek
Keyword(s):  
Mach Number ◽  
Flow Field ◽  
Degrees Of Freedom ◽  
Air Flow ◽  
Optical Measurements ◽  
Energy Contribution ◽  
Aerodynamic Forces ◽  
Unsteady Aerodynamic ◽  
New Information ◽  
Drag And Lift

The study presents evaluation of optical measurements of the air flow field near the fluttering profile NACA0015 with two-degrees of freedom, Mach number of the flutter occurrence were M=0.21 and M=0.45. Aerodynamic forces (drag and lift components) were evaluated independently on the upper and lower surfaces of the profile. Using the mentioned decomposition, the new information about mechanism of flutter properties was obtained. The forces on the upper and lower surfaces are phase shifted and are partially eliminated as a result of the circulation around the profile. The cycle changes of these forces cause the permanent energy contribution from the airflow to the vibrating system.

scholarly journals Aerodynamic Detuning Analysis of an Unstalled Supersonic Turbofan Cascade

1986 ◽  
Vol 108 (1) ◽  
pp. 60-67 ◽  
Author(s):  
D. Hoyniak ◽  
S. Fleeter
Keyword(s):  
Flow Field ◽  
Leading Edge ◽  
Rotor Blades ◽  
Driving Mechanism ◽  
Aeroelastic Stability ◽  
Aerodynamic Forces ◽  
Unsteady Aerodynamic ◽  
Influence Coefficients ◽  
Blade Row ◽  
The Stability

A new, and as yet unexplored, approach to passive flutter control is aerodynamic detuning, defined as designed passage-to-passage differences in the unsteady aerodynamic flow field of a rotor blade row. Thus, aerodynamic detuning directly affects the fundamental driving mechanism for flutter, i.e., the unsteady aerodynamic forces and moments acting on individual rotor blades. In this paper, a model to demonstrate the enhanced supersonic unstalled aeroelastic stability associated with aerodynamic detuning is developed. The stability of an aerodynamically detuned cascade operating in a supersonic inlet flow field with a subsonic leading edge locus is analyzed, with the aerodynamic detuning accomplished by means of nonuniform circumferential spacing of adjacent rotor blades. The unsteady aerodynamic forces and moments on the blading are defined in terms of influence coefficients in a manner that permits the stability of both a conventional uniformly spaced rotor configuration as well as the detuned nonuniform circumferentially spaced rotor to be determined. With Verdon’s uniformly spaced Cascade B as a baseline, this analysis is then utilized to demonstrate the potential enhanced aeroelastic stability associated with this particular type of aerodynamic detuning.

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