The influence of gap- and chord-widths for multi-box girders: Superposition of flat plate flutter derivatives and section model tests

2022 ◽  
Vol 109 ◽  
pp. 103489
Author(s):  
Michael Styrk Andersen ◽  
Mads Beedholm Eriksen ◽  
Søren Vestergaard Larsen ◽  
Anders Brandt
Keyword(s):  
Flat Plate ◽  
Model Tests ◽  
Box Girders ◽  
Plate Flutter ◽  
Section Model ◽  
Flutter Derivatives

Section model tests on human – structure lock-in

2003 ◽  
Vol 156 (2) ◽  
pp. 71-79 ◽  
Author(s):  
A. McRobie ◽  
G. Morgenthal ◽  
J. Lasenby ◽  
M. Ringer
Keyword(s):  
Model Tests ◽  
Section Model ◽  
Lock In

Comparison Between Static, Forced Oscillation and Free Oscillation Model Tests for the Assessment of Galloping Instability at High Reynolds Numbers

2013 ◽  
Author(s):  
Alexandre Cinello ◽  
François Pétrié ◽  
Thierry Rippol ◽  
Bernard Molin ◽  
Guillaume Damblans
Keyword(s):  
Cross Sections ◽  
Cross Flow ◽  
Reynolds Numbers ◽  
Model Tests ◽  
Square Cylinder ◽  
Vortex Induced Vibrations ◽  
Electric Power Line ◽  
Section Model ◽  
High Reynolds ◽  
Fixed Cylinder

Galloping may take place for non-circular cross sections, such as an ice-coated electric power line or a riser bundle, under current action. This type of instabilities occurs at lower frequency than Vortex Induced Vibrations but with unbounded amplitude, and might be detrimental for riser integrity. In a recent joint industry project, the CITEPH “Gallopan” project, galloping instabilities were investigated for two types of cylinders: an academic square cylinder and a generic riser tower cross section. Model tests and numerical computations were performed to assess the propensity of both cylinders to gallop. Experiments on the square cylinder are reported here. Three types of tests were performed in steady flow: loads measurement on fixed cylinder, at various headings; loads measurement on the cylinder with over imposed cross-flow harmonic oscillations; free transverse oscillations. By using analytical calculations, the ability to predict galloping instability occurrence and amplitude, of each of the three above methods, was compared. Compared to typical results found in literature, these experiments were conducted at a larger scale, and thus with Reynolds number closer to on-site values, i.e. over 105.

Investigation on the effect of vibration frequency on vortex-induced vibrations by section model tests

2015 ◽  
Vol 20 (2) ◽  
pp. 349-361 ◽  
Author(s):  
X.G. Hua ◽  
Z.Q. Chen ◽  
W. Chen ◽  
H.W. Niu ◽  
Z.W. Huang
Keyword(s):  
Vibration Frequency ◽  
Model Tests ◽  
Vortex Induced Vibrations ◽  
Section Model

Flutter Derivatives of the Kao-Pin Hsi Cable-Supported Bridge

2016 ◽  
Vol 821 ◽  
pp. 172-179
Author(s):  
Andrija Buljac ◽  
Stanislav Pospíšil ◽  
Hrvoje Kozmar ◽  
Sergej Kuznetsov ◽  
Radomil Král
Keyword(s):  
Flat Plate ◽  
Bridge Deck ◽  
Engineering Structures ◽  
Long Span ◽  
Vibration Technique ◽  
Centre Of Excellence ◽  
Double Degree ◽  
Torsional Instability ◽  
Large Width ◽  
Flutter Derivatives

Long-span cable-supported bridges, characterized with low natural frequencies and mechanical damping, are very sensitive to wind effects. Therefore, investigation of the aeroelastic behaviour of bridges is particularly important when designing these complex engineering structures. The focus is on evaluation of dimensionless aeroelastic coefficients, i.e. flutter derivatives, which are considered as indicators of the aeroelastic stability of bridges. A comprehensive experimental study on dynamic wind-induced behaviour of the Kao-Pin Hsi Bridge in Taiwan is carried out in the Climatic Wind Tunnel of the Centre of Excellence Telč (CET), Czech Republic. The bridge-deck section is tested at a multipurpose experimental setup originally developed in the CET. Flutter derivatives are obtained by the means of the free-vibration technique for the double-degree-of-freedom (DDOF) system. The results are compared to those of a thin flat plate with large width to height ratio, which previously proved to be stable with respect to the flutter phenomenon. While the torsional instability is observed for the Kao-Pin Hsi bridge-deck section, the flat plate proves to be aeroelastically stable.

Unsteady Flow Over a Dragonfly Wing-Section Model

2009 ◽  
Author(s):  
Sadid Salajegheh ◽  
Mehran Tadjfar
Keyword(s):  
Reynolds Number ◽  
Unsteady Flow ◽  
Flat Plate ◽  
Steady Flow ◽  
Aerodynamic Performance ◽  
Dragonfly Wing ◽  
Wing Section ◽  
Flow Reynolds Number ◽  
Section Model ◽  
Better Than

Here we study the flapping of a dragonfly’s wing section where the frequency of the wing flapping is about 25–30 HZ. We have translational and rotational velocities in a single stroke. In this article we investigate dragonfly’s 2D sections and we want to study the effect of the corrugations during unsteady flight at low Reynolds number. We find that in contrast to the published results for steady flow over the wings, where the corrugation seems to have improved the performance over a profiled wing-section, here a simple flat plate seems to perform better than the corrugated one. However, the corrugated wing-sections have a better aerodynamic performance than the traditional profiled wing-sections. The flow Reynolds number in this study is 8000.

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