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Research Papers: Fundamental Issues and Canonical Flows

Numerical Study of Slat Screen Pattern Effect on Design Parameters of Tuned Liquid Dampers

[+] Author and Article Information
Morteza Marivani

Thermal Processing Laboratory,
Department of Mechanical Engineering,
McMaster University,
Hamilton, Ontario, Canada
e-mail: marivani.m@gmail.com

M. S. Hamed

Thermal Processing Laboratory,
Department of Mechanical Engineering,
McMaster University,
Hamilton, Ontario, Canada

1Corresponding author.

Contributed by the Fluids Engineering Division of ASME for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received October 5, 2010; final manuscript received January 7, 2014; published online April 28, 2014. Assoc. Editor: Meng Wang.

J. Fluids Eng 136(6), 061201 (Apr 28, 2014) (11 pages) Paper No: FE-10-1344; doi: 10.1115/1.4026662 History: Received October 05, 2010; Revised January 07, 2014

Tuned liquid dampers (TLDs) are considered economical and effective dynamic vibration absorbers. They are increasingly being used to mitigate the dynamic resonant response of tall buildings and it is often designed to reduce the structure's acceleration at a serviceability limit state. Slat screens can increase the inherent damping factor of TLDs. They have been used as a common flow damping device in TLDs because of the simplicity of using them and also the ability to control their effects on the performance of a TLD. Two slat screens with the same solidity ratio and different patterns could have different effects on the TLD's performance. Many former numerical researches used the potential and linear theory as a base to describe the fluid flow behavior inside the TLD. The applicability of the linearized flow models was for the condition of the low amplitude of excitations. Under large excitation events such as high return period wind storms or earthquakes, the assumptions of linear theory are no longer valid. Moreover, in the linearized model, screens were modeled as a hydraulic resistance point as a function of the screen solidity ratio without the ability to consider the effect of screen pattern. In the present study, a numerical algorithm has been developed which can handle both the small and large amplitude of excitations. In this algorithm, the fluid flow through the screen is fully resolved and it can take into account the effect of the screen pattern on the TLD's performance. The major focus of this paper is to use this developed algorithm and conduct a numerical investigation to study the effects of the slat screen pattern on the inherent damping and natural frequency of the TLD, as the design parameters of the TLD. In this numerical investigation a selected TLD outfitted by different slat screens and interacted with the structure is exposed by both harmonic and random external excitations. The numerical results have been validated against experimental work. The effect of slat screen pattern on the damping effect and natural frequency of a TLD has been presented. Also in this study, two new parameters termed as slat ratio (SR) and effective solidity ratio (Seff) are presented to imply the physical significance of screen pattern.

Copyright © 2014 by ASME
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References

Figures

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Fig. 3

Schematic of a coupled TLD–structure system

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Fig. 2

Geometrical details of the slat screen

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Fig. 1

Dimensions of the TLD

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Fig. 4

The tune liquid damper tank setup side view [6]

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Fig. 5

The random excitation force applied to the TLD–structure system

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Fig. 6

Time history comparison of experimental results [6] and numerical results for (a) free surface response at the axial location of x = 0.05 L, (b) normalized TLD force, and (c) structural acceleration time histories

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Fig. 7

Variation of the normalized sloshing force F′ as function of excitation frequency ratio βw at amplitude of excitations of (a) 2.5 mm and (b) 12.5 mm

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Fig. 16

The effect of the variation of slat ratio on sloshing force of the TLD subjected to random excitation

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Fig. 8

Slat screen characteristic dimensions

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Fig. 9

Configuration of screens with the same solidity ratio (S) and with different slat ratios (SR)

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Fig. 12

The effect of the variation of slat ratio on sloshing force of the TLD subjected to harmonic excitation

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Fig. 13

The effect of the variation of slat ratio on the structure acceleration equipped with this TLD subjected to harmonic excitation

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Fig. 14

The effect of the variation of slat ratio on flow pattern inside the TLD subjected to a random excitation

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Fig. 15

The effect of the variation of slat ratio on deformation of free surface at the axial location of x = 0.05 L of the TLD subjected to random excitation

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Fig. 18

The effect of the variation of slat ratio on the acceleration of structure equipped by this TLD subjected to random excitation

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Fig. 10

The effect of the variation of slat ratio on flow pattern inside the TLD subjected to a harmonic excitation

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Fig. 11

The effect of the variation of slat ratio on deformation of free surface at the axial location of x = 0.05 L of the TLD subjected to harmonic excitation

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Fig. 17

The effect of the variation of slat ratio on the structure response equipped with this TLD subjected to random excitation

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Fig. 19

Configuration of slat screens used in the frequency sweep analysis

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Fig. 20

The relation between the maximum free surface deflection and the sloshing frequencies detected by the frequency sweep analysis

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Fig. 21

Flow patterns around the screen: (a) the screen with solidity ratio of 0.42 and slat ratio of 0.2 and (b) the screen with solidity ratio of 0.42 and slat ratio of 0.5

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