The effect of mass ratio on the structural response of a freely vibrating square cylinder oriented at different angles of attack

Jisheng Zhao, Justin Leontini, David Lo Jacono, John Sheridan

Research output: Contribution to journalArticleResearchpeer-review

Abstract

This study reports on an experimental investigation of the effect of mass ratio on the transverse flow-induced vibration (FIV) response of an elastically mounted square cylinder placed at three different incidence angles: two symmetric with respect to the centreplane, α=0° and 45°; and one asymmetric at 20°. These three angles display different dominant FIV phenomena: transverse galloping and combined vortex-induced vibration (VIV) and galloping for α=0°, VIV for α=45°, and higher branch subharmonic (period-doubled) VIV for α=20° (Nemes et al., 2012). The mass ratio is defined as the ratio of the total oscillating mass (m) to the displaced fluid mass (m d ), m =m∕m d . The present results show that the mass ratio (m =2.64 – 15.00) has a significant influence on the structural vibration response for all FIV phenomena, and can dictate whether two of these modes exist at all. Three primary observations are presented: for the α=0° case, the combined VIV–galloping response is diminished as the mass ratio is increased, and it ceases to exist for m ⩾11.31; for the α=45° case, the peak values of the normalised oscillation amplitude during VIV are only reduced marginally with increasing m , however the body oscillation amplitude in the desynchronised regions is significantly attenuated; for the α=20° case, there exists a critical mass ratio (m crit ≃3.50) above which the higher branch subharmonic VIV does not persist.

Original languageEnglish
Pages (from-to)200-212
Number of pages13
JournalJournal of Fluids and Structures
Volume86
DOIs
Publication statusPublished - 1 Apr 2019

Keywords

  • Flow-induced vibration
  • Fluid–structure interaction
  • Square cylinder

Cite this

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title = "The effect of mass ratio on the structural response of a freely vibrating square cylinder oriented at different angles of attack",
abstract = "This study reports on an experimental investigation of the effect of mass ratio on the transverse flow-induced vibration (FIV) response of an elastically mounted square cylinder placed at three different incidence angles: two symmetric with respect to the centreplane, α=0° and 45°; and one asymmetric at 20°. These three angles display different dominant FIV phenomena: transverse galloping and combined vortex-induced vibration (VIV) and galloping for α=0°, VIV for α=45°, and higher branch subharmonic (period-doubled) VIV for α=20° (Nemes et al., 2012). The mass ratio is defined as the ratio of the total oscillating mass (m) to the displaced fluid mass (m d ), m ∗ =m∕m d . The present results show that the mass ratio (m ∗ =2.64 – 15.00) has a significant influence on the structural vibration response for all FIV phenomena, and can dictate whether two of these modes exist at all. Three primary observations are presented: for the α=0° case, the combined VIV–galloping response is diminished as the mass ratio is increased, and it ceases to exist for m ∗ ⩾11.31; for the α=45° case, the peak values of the normalised oscillation amplitude during VIV are only reduced marginally with increasing m ∗ , however the body oscillation amplitude in the desynchronised regions is significantly attenuated; for the α=20° case, there exists a critical mass ratio (m crit ∗ ≃3.50) above which the higher branch subharmonic VIV does not persist.",
keywords = "Flow-induced vibration, Fluid–structure interaction, Square cylinder",
author = "Jisheng Zhao and Justin Leontini and {Lo Jacono}, David and John Sheridan",
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doi = "10.1016/j.jfluidstructs.2019.02.008",
language = "English",
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The effect of mass ratio on the structural response of a freely vibrating square cylinder oriented at different angles of attack. / Zhao, Jisheng; Leontini, Justin; Lo Jacono, David; Sheridan, John.

In: Journal of Fluids and Structures, Vol. 86, 01.04.2019, p. 200-212.

Research output: Contribution to journalArticleResearchpeer-review

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T1 - The effect of mass ratio on the structural response of a freely vibrating square cylinder oriented at different angles of attack

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AU - Leontini, Justin

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N2 - This study reports on an experimental investigation of the effect of mass ratio on the transverse flow-induced vibration (FIV) response of an elastically mounted square cylinder placed at three different incidence angles: two symmetric with respect to the centreplane, α=0° and 45°; and one asymmetric at 20°. These three angles display different dominant FIV phenomena: transverse galloping and combined vortex-induced vibration (VIV) and galloping for α=0°, VIV for α=45°, and higher branch subharmonic (period-doubled) VIV for α=20° (Nemes et al., 2012). The mass ratio is defined as the ratio of the total oscillating mass (m) to the displaced fluid mass (m d ), m ∗ =m∕m d . The present results show that the mass ratio (m ∗ =2.64 – 15.00) has a significant influence on the structural vibration response for all FIV phenomena, and can dictate whether two of these modes exist at all. Three primary observations are presented: for the α=0° case, the combined VIV–galloping response is diminished as the mass ratio is increased, and it ceases to exist for m ∗ ⩾11.31; for the α=45° case, the peak values of the normalised oscillation amplitude during VIV are only reduced marginally with increasing m ∗ , however the body oscillation amplitude in the desynchronised regions is significantly attenuated; for the α=20° case, there exists a critical mass ratio (m crit ∗ ≃3.50) above which the higher branch subharmonic VIV does not persist.

AB - This study reports on an experimental investigation of the effect of mass ratio on the transverse flow-induced vibration (FIV) response of an elastically mounted square cylinder placed at three different incidence angles: two symmetric with respect to the centreplane, α=0° and 45°; and one asymmetric at 20°. These three angles display different dominant FIV phenomena: transverse galloping and combined vortex-induced vibration (VIV) and galloping for α=0°, VIV for α=45°, and higher branch subharmonic (period-doubled) VIV for α=20° (Nemes et al., 2012). The mass ratio is defined as the ratio of the total oscillating mass (m) to the displaced fluid mass (m d ), m ∗ =m∕m d . The present results show that the mass ratio (m ∗ =2.64 – 15.00) has a significant influence on the structural vibration response for all FIV phenomena, and can dictate whether two of these modes exist at all. Three primary observations are presented: for the α=0° case, the combined VIV–galloping response is diminished as the mass ratio is increased, and it ceases to exist for m ∗ ⩾11.31; for the α=45° case, the peak values of the normalised oscillation amplitude during VIV are only reduced marginally with increasing m ∗ , however the body oscillation amplitude in the desynchronised regions is significantly attenuated; for the α=20° case, there exists a critical mass ratio (m crit ∗ ≃3.50) above which the higher branch subharmonic VIV does not persist.

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