scholarly journals Low speed flutter and limit cycle oscillations of a two-degree-of-freedom flat plate in a wind tunnel

2013 ◽  
Vol 43 ◽  
pp. 244-255 ◽  
Author(s):  
X. Amandolese ◽  
S. Michelin ◽  
M. Choquel
Keyword(s):  
Wind Tunnel ◽  
Flat Plate ◽  
Limit Cycle ◽  
Degree Of Freedom ◽  
Limit Cycle Oscillations ◽  
Low Speed ◽  
Two Degree Of Freedom

Triggering Mechanisms of Limit Cycle Oscillations in a Two Degree-of-Freedom Wing Flutter Model

2005 ◽  
Author(s):  
Young S. Lee ◽  
Alexander F. Vakakis ◽  
Lawrence A. Bergman ◽  
D. Michael McFarland ◽  
Gae¨tan Kerschen
Keyword(s):  
Limit Cycle ◽  
Degree Of Freedom ◽  
Resonance Capture ◽  
Limit Cycle Oscillations ◽  
Wing Flutter ◽  
Wing Model ◽  
Pitch Frequency ◽  
Frequency Components ◽  
Triggering Mechanisms ◽  
Two Degree Of Freedom

We show numerically that the triggering mechanisms of limit cycle oscillations (LCOs) due to aeroelastic instability are composed of a series of resonance captures. We consider a two degree-of-freedom (DOF) wing model with cubic nonlinear stiffnesses in the support, assuming quasi-steady aerodynamics and subsonic flow around the wing. Then, we establish the slow flow dynamics model, using the complexification / averaging technique and considering three frequency components; i.e., the two linear natural frequencies corresponding to heave and pitch and the superharmonic component which appears as three times the pitch frequency. It turns out that the LCO triggering mechanisms consist of mainly three stages: (i) transient resonance capture (TRC); (ii) escape; and (iii) permanent resonance capture (PRC). We examine the characteristics of each stage by way of time response, wavelet transform, phase plane, and instantaneous energy.

Extensions to Maskell’s theory for blockage effects on bluff bodies in a closed wind tunnel

2001 ◽  
Vol 105 (1050) ◽  
pp. 409-418 ◽  
Author(s):  
J. E. Hackett ◽  
K. R. Cooper
Keyword(s):  
Wind Tunnel ◽  
Flat Plate ◽  
Correction Method ◽  
The Other ◽  
Bluff Bodies ◽  
Low Speed ◽  
Test Conditions ◽  
Lift And Drag ◽  
Low Speed Wind Tunnel

Abstract Extensions to Maskell’s original correction method, developed over several years, are consolidated and designated ‘Maskell III’. The procedures were applied to dedicated tests on a family of flat-plate wing models in a small, low-speed wind tunnel at NRC. Test conditions included angles of attack from -10° to 110° and models of up to 16% of tunnel area. Off-centre tests were included with model-to-wall distances down to 0.72 chords. Corrected lift and drag data correlated well between models of different sizes and at different offsets from the tunnel centreline. Comparisons are made with corrections using the pressure-signature and two-variable methods, emphasising post-stall conditions. These showed that the ‘Maskell III’ procedures, which require minimal input, correlated as well as the other methods for most model sizes and positions in the tunnel.

Control of a Wing Type Flat-Plate for an Ornithopter Autonomous Robot With Differential Flatness

2020 ◽  
pp. 209-245
Author(s):  
Elkin Yesid Veslin Díaz ◽  
Cesar Francisco Bogado-Martínez ◽  
Max Suell Dutra ◽  
Luciano Santos Constantin Raptopoulos
Keyword(s):  
Flat Plate ◽  
Wind Velocity ◽  
Feedback Loop ◽  
Angle Of Attack ◽  
Autonomous Robot ◽  
Degree Of Freedom ◽  
Differential Flatness ◽  
Control Scheme ◽  
Three Degree Of Freedom ◽  
Two Degree Of Freedom

In this chapter, a two-degree-of-freedom controller that exploits the flat properties of a three degree-of-freedom wing type flat-plate for an Ornithopter Autonomous robot is proposed. A set of kinematical patterns inspired by nature is used to simulate the wing's movement around two wingtip trajectories; also, the effects of the aerodynamical forces as a function of the wind velocity and the wing's angle of attack are considered. In order to control the system, the effects of these forces are viewed as disturbs that affect the wing's dynamics. The proposed control scheme drives the device through the desired path by generating a set of desired inputs which are compensated by a feedback loop when the aerodynamical forces actuate upon the system.

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