Flow-induced vibration of a cube orientated at different incidence angles

Research output: Contribution to journalArticleResearchpeer-review

Abstract

This study experimentally investigates the transverse flow-induced vibration (FIV) of an elastically mounted cube at three different incidence angles of α=0, 20 and 45, corresponding to two centreplane mirror-symmetric cases and one asymmetric case. The FIV response is characterised by analysing the vibration amplitude and frequency responses, together with the fluid force coefficients and phases, over the reduced velocity range of 1.2⩽U⩽16. Here, U=U∕(fnwH), with U the free-stream velocity, fnw the natural frequency of the system in quiescent fluid (water) and H the frontal projected width of the body. It was found in the α=0 case that two synchronisation regions could be identified, where the periodic body vibration was synchronised with oscillatory shear layers. The vibration amplitude was found to increase with U in the second synchronisation region, with the largest value of Amax ≃0.74 observed at the highest U value tested. In the asymmetric orientation case of α=20, a synchronisation region occurred over 6.0<U<8.6, where the amplitude tended to increase to its local peak of Amax ≃0.25 at U=8.6. For higher U values, synchronisation was lost, but the cube still exhibited high amplitude oscillations. However, in the α=45 case, while the vibration amplitude tended to increase with U (i.e. Amax ≈0.3 at U=16), the FIV response was found to be desynchronised over the entire U range. The findings indicate that body vibration is strongly coupled with the oscillatory separating shear layers for all α cases, which can result in significant vibration.

Original languageEnglish
Article number102701
Number of pages19
JournalJournal of Fluids and Structures
Volume91
DOIs
Publication statusPublished - 1 Nov 2019

Keywords

  • Bluff body wakes
  • Cube
  • Flow-induced vibration

Cite this

@article{bc268c792c5e446c9a5e2e0aa42178e9,
title = "Flow-induced vibration of a cube orientated at different incidence angles",
abstract = "This study experimentally investigates the transverse flow-induced vibration (FIV) of an elastically mounted cube at three different incidence angles of α=0∘, 20∘ and 45∘, corresponding to two centreplane mirror-symmetric cases and one asymmetric case. The FIV response is characterised by analysing the vibration amplitude and frequency responses, together with the fluid force coefficients and phases, over the reduced velocity range of 1.2⩽U∗⩽16. Here, U∗=U∕(fnwH), with U the free-stream velocity, fnw the natural frequency of the system in quiescent fluid (water) and H the frontal projected width of the body. It was found in the α=0∘ case that two synchronisation regions could be identified, where the periodic body vibration was synchronised with oscillatory shear layers. The vibration amplitude was found to increase with U∗ in the second synchronisation region, with the largest value of Amax ∗≃0.74 observed at the highest U∗ value tested. In the asymmetric orientation case of α=20∘, a synchronisation region occurred over 6.0<U∗<8.6, where the amplitude tended to increase to its local peak of Amax ∗≃0.25 at U∗=8.6. For higher U∗ values, synchronisation was lost, but the cube still exhibited high amplitude oscillations. However, in the α=45∘ case, while the vibration amplitude tended to increase with U∗ (i.e. Amax ∗≈0.3 at U∗=16), the FIV response was found to be desynchronised over the entire U∗ range. The findings indicate that body vibration is strongly coupled with the oscillatory separating shear layers for all α cases, which can result in significant vibration.",
keywords = "Bluff body wakes, Cube, Flow-induced vibration",
author = "Jisheng Zhao and John Sheridan and Kerry Hourigan and Thompson, {Mark C.}",
year = "2019",
month = "11",
day = "1",
doi = "10.1016/j.jfluidstructs.2019.102701",
language = "English",
volume = "91",
journal = "Journal of Fluids and Structures",
issn = "0889-9746",
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Flow-induced vibration of a cube orientated at different incidence angles. / Zhao, Jisheng; Sheridan, John; Hourigan, Kerry; Thompson, Mark C.

In: Journal of Fluids and Structures, Vol. 91, 102701, 01.11.2019.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Flow-induced vibration of a cube orientated at different incidence angles

AU - Zhao, Jisheng

AU - Sheridan, John

AU - Hourigan, Kerry

AU - Thompson, Mark C.

PY - 2019/11/1

Y1 - 2019/11/1

N2 - This study experimentally investigates the transverse flow-induced vibration (FIV) of an elastically mounted cube at three different incidence angles of α=0∘, 20∘ and 45∘, corresponding to two centreplane mirror-symmetric cases and one asymmetric case. The FIV response is characterised by analysing the vibration amplitude and frequency responses, together with the fluid force coefficients and phases, over the reduced velocity range of 1.2⩽U∗⩽16. Here, U∗=U∕(fnwH), with U the free-stream velocity, fnw the natural frequency of the system in quiescent fluid (water) and H the frontal projected width of the body. It was found in the α=0∘ case that two synchronisation regions could be identified, where the periodic body vibration was synchronised with oscillatory shear layers. The vibration amplitude was found to increase with U∗ in the second synchronisation region, with the largest value of Amax ∗≃0.74 observed at the highest U∗ value tested. In the asymmetric orientation case of α=20∘, a synchronisation region occurred over 6.0<U∗<8.6, where the amplitude tended to increase to its local peak of Amax ∗≃0.25 at U∗=8.6. For higher U∗ values, synchronisation was lost, but the cube still exhibited high amplitude oscillations. However, in the α=45∘ case, while the vibration amplitude tended to increase with U∗ (i.e. Amax ∗≈0.3 at U∗=16), the FIV response was found to be desynchronised over the entire U∗ range. The findings indicate that body vibration is strongly coupled with the oscillatory separating shear layers for all α cases, which can result in significant vibration.

AB - This study experimentally investigates the transverse flow-induced vibration (FIV) of an elastically mounted cube at three different incidence angles of α=0∘, 20∘ and 45∘, corresponding to two centreplane mirror-symmetric cases and one asymmetric case. The FIV response is characterised by analysing the vibration amplitude and frequency responses, together with the fluid force coefficients and phases, over the reduced velocity range of 1.2⩽U∗⩽16. Here, U∗=U∕(fnwH), with U the free-stream velocity, fnw the natural frequency of the system in quiescent fluid (water) and H the frontal projected width of the body. It was found in the α=0∘ case that two synchronisation regions could be identified, where the periodic body vibration was synchronised with oscillatory shear layers. The vibration amplitude was found to increase with U∗ in the second synchronisation region, with the largest value of Amax ∗≃0.74 observed at the highest U∗ value tested. In the asymmetric orientation case of α=20∘, a synchronisation region occurred over 6.0<U∗<8.6, where the amplitude tended to increase to its local peak of Amax ∗≃0.25 at U∗=8.6. For higher U∗ values, synchronisation was lost, but the cube still exhibited high amplitude oscillations. However, in the α=45∘ case, while the vibration amplitude tended to increase with U∗ (i.e. Amax ∗≈0.3 at U∗=16), the FIV response was found to be desynchronised over the entire U∗ range. The findings indicate that body vibration is strongly coupled with the oscillatory separating shear layers for all α cases, which can result in significant vibration.

KW - Bluff body wakes

KW - Cube

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DO - 10.1016/j.jfluidstructs.2019.102701

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VL - 91

JO - Journal of Fluids and Structures

JF - Journal of Fluids and Structures

SN - 0889-9746

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