Correlation Structures of Pressure Field and Integrated Forces on Oscillating Prism in Turbulent Flows

Haan, Fred L.; Wu, Teng; Kareem, Ahsan

doi:10.1061/(asce)em.1943-7889.0001058

Cited by 12 publications

(3 citation statements)

References 27 publications

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“…Compared with previous researches (Haan et al, 2016;Li et al, 2016;Sarkar et al, 2009), the cases of large amplitude single pitching and single heaving motion, as well as coupled motion, were considered in this test campaign . The amplitude of single pitching motion  0 ranges from 2° to 16°, while the single heaving amplitude h 0 ranges from 3mm to about 27mm (corresponding to h 0 /B from 0.6%to 5.5%).…”

Section: Testing Casesmentioning

confidence: 99%

“…separation and vortex formation processes); therefore additional measurements should be conducted on the pressure field. Beyond a few forced motion tests for 5:1 rectangular cylinders, pressures of rectangles with aspect ratio of 6.67:1 under imposed heaving and small pitching motion were measured in both smooth and turbulent flow (Haan et al, 2016). The motioninduced forces were investigated through the ordinary flutter derivatives' theory (Scanlan, 1978).…”

Section: Introductionmentioning

confidence: 99%

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Effects of oscillation amplitude on motion-induced forces for 5:1 rectangular cylinders

Lin

Wang

Nikitas

et al. 2019

Journal of Wind Engineering and Industrial Aerodynamics

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While the 5:1 rectangular cylinder is a benchmark section, studied extensively, there are limited experimental studies commenting on any amplitude-dependence of its motion-induced forces. To this goal, such a cylinder is tested in wind tunnel through a forced vibration protocol for extracting distributed simultaneous pressure measurements under smooth flow conditions and for different heaving, pitching and coupled motion amplitudes. Ordinary flutter derivatives are extracted, and discrepancies due to oscillation amplitude are scrutinized. Spectral analysis is performed for the developing motion-induced forces, and it is found that torsional amplitudes above a threshold would increase higher harmonic frequency content. The phenomenon was also confirmed by means of Probability Density Functions and (PDFs) the Proper Orthogonal Decomposition (POD) of the unsteady wind force. In order to understand the link between the observed amplitude dependence and the flow field variation, the movement of the reattachment point on the cylinder surface is investigated by interpreting statistics of the recorded pressure measurements. The response in terms of instantaneous angle of attack is proven to be incompatible with respect to observations, since equal amplitudes of this variable result to different motion-induced forces.

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Section: Testing Casesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of oscillation amplitude on motion-induced forces for 5:1 rectangular cylinders

Lin

Wang

Nikitas

et al. 2019

Journal of Wind Engineering and Industrial Aerodynamics

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“…The section model wind tunnel tests are based on the assumptions that the shed vortices are two dimensional and the excitation forces due to vortex shedding are fully correlated along the length of the model. However, vortex-induced lift forces over the entire span in prototype bridges do not fully correlated in particular at small amplitudes of vibration, and can vary case by case for different bridge deck cross-sections [11][12][13]. Lack of knowledge on the correlation of excitation forces could lead to discrepancy between section model experiments and full scale [14].…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of correction factor for VIV amplitude of flexible bridges from an aeroelastic model and its 1:1 section model

Zhou

Hua

Chen

et al. 2017

Engineering Structures

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Evaluation of the maximum amplitudes of vortex-induced vibrations (VIV) in suspension bridges is mainly relied upon section model wind tunnel tests of bridge decks. Extrapolation to prototype responses requires addition correction to take into account the differences both in structural mode shape and in spanwise correlation of excitation forces between the section model and the prototype. The paper presents the results of VIV amplitudes measured on an aeroelastic model and on its section model with the same size of cross-section. The aeroelastic model is a new, elastically multi-supported one which is capable of reproducing the closely-spaced vertical modes of a suspension bridge. The vortex-induced vibrations for a number of vertical modes were successfully measured from the aeroelastic model test in smooth flow. The spring-mounted section model having the same size of cross-section as the aeroelastic model was also tested in smooth flow at the same mass, damping ratio and vibration frequency. It is shown that both the VIV onset wind velocity and lock-in range for each mode of vibration are in good agreement between the aeroelastic model and the section model. The aeroelastic model consistently produces a roughly 30% higher maximum amplitude than the section model for the observed modes of vibration. It is confirmed that the combined three-dimensional (3D) effects due to mode shape and imperfect correlation of excitation forces amplify the VIV amplitudes and disregarding these effects may underestimate the VIV amplitudes for section model tests. A correction factor of 1.3 for the VIV amplitude of vertical modes in suspension bridges may be adopted for practical use when extrapolating the section-model results to their corresponding full-scale values.

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Aerodynamic admittance of streamlined bridge decks

Larose³

2018

Journal of Fluids and Structures

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Correlation Structures of Pressure Field and Integrated Forces on Oscillating Prism in Turbulent Flows

Cited by 12 publications

References 27 publications

Effects of oscillation amplitude on motion-induced forces for 5:1 rectangular cylinders

Effects of oscillation amplitude on motion-induced forces for 5:1 rectangular cylinders

Experimental investigation of correction factor for VIV amplitude of flexible bridges from an aeroelastic model and its 1:1 section model

Aerodynamic admittance of streamlined bridge decks

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