Reduction of flow-induced forces on a circular cylinder using a detached splitter plate

Hwang, Jong‐Yeon; Yang, Kyung‐Soo; Sun, Seung-Han

doi:10.1063/1.1583733

Cited by 197 publications

(66 citation statements)

References 9 publications

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“…Looking at our baseline case for SSG at U ∞ = 11 m/s for consistency, we find that for x sp /t 0 = 3 the value of T u peak decreases from 0.146 to 0.107, a reduction of 27%. Moreover, x sp /t 0 = 3 is close to x sp /D = 2.5 − 2.7, which was found to be the optimal distance for suppressing vortex shedding from a circular cylinder (see Roshko, 1954;Lin and Wu, 1994;Hwang et al, 2003).…”

Section: Vortex Shedding Suppressionmentioning

confidence: 99%

Vortex shedding effects in grid-generated turbulence

2016

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The flow on the centerline of grid-generated turbulence is characterised via hot-wire anemometry for 3 grids with different geometry: a regular grid (RG60), a fractal grid (FSG17) and a single square grid (SSG).Thanks to a higher value of the thickness t0 of its bars, SSG produces greater values of turbulence intensity T u than FSG17, despite SSG having a smaller blockage ratio. However the higher T u for SSG is mainly due to a more pronounced vortex shedding contribution. The effects of vortex shedding suppression along the streamwise direction x are studied by testing a new 3D configuration, formed by SSG and a set of four splitter plates detached from the grid (SSG+SP). When vortex shedding is damped, the centerline location of the peak of turbulence intensity x peak moves downstream and T u considerably decreases in the production region. For FSG17 the vortex shedding is less intense and it disappears more quickly, in terms of x/x peak , when compared to all the other configurations. When vortex shedding is attenuated, the integral length scale Lu grows more slowly in the streamwise direction, this being verified both for FSG17 and for SSG+SP.In the production region, there is a correlation between the vortex shedding energy and the skewness and the flatness of the velocity fluctuations. When vortex shedding is not significant, the skewness is highly negative and the flatness is much larger than 3. On the opposite side, when vortex shedding is prominent, the non-Gaussian behaviour of the velocity fluctuations becomes masked.

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Section: Vortex Shedding Suppressionmentioning

confidence: 99%

Vortex shedding effects in grid-generated turbulence

2016

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“…Theposition and length of ribbons have a significant effect on the drag reduction. Hwang et al [7] applied a detached splitter plate for the control of flowinduced forces on a circular cylinder in their numerical study of laminar flow. They revealed that optimal location of splitter plate reduces the drag coefficient.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Effect of Boundary Layer on Flow Structure Around a Cylinder with a Strip

Yayla

Tekşin

2015

EPJ Web of Conferences

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Abstract. In this study, the flow characteristic of the circular cylinder was placed vertically in channel which has dimensions as 8000 mm, 1000 mm, 750 mm, lenght, width and height repectively, was investigated. The cylinder was located in boundary layer with a diameter of 60 mm (D) and a elastic stripwhich has a 1400 N/mm 2 modulus of elasticity vinyl PVC transperent film was attached behind the cylinder. Lenght of the strip (L) was 240 mm L/D=4. The Reynolds number was fixed at Re=7500. The time-averaged and instantaneous velocity vector maps, vorticity contours, Reynold shear and normal stresses, turbulent kinetic energy and frequency of shedding were obtained using the particle image velocimetry (PIV) technique. It was found that the elastic plate which exists behind the cylinder has a slight influence on the flow structure of the wake-boundary layer interaction. Values of turbulent kinetic energy, streamwise Reynold stress, transverse Reynold stresses were decreased by attaching strip.

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“…Reduction of VIV amplitude is a method that reduces stresses and fatigue damage which can be achieved using different ways such as increasing structural damping, avoiding resonance and manipulate the wake. [5]), shrouds (Zdravkovich [6]), splitter plate (Hwang et al [7]), rear-wake stabilizer (Eisenlohr and Eckelmann [8]), and small rods (Zhao et al [9]; Zhao et al [10]). Geometric modifications of cylinder wall are the main methods for these passive controls, which inevitably increase the mass ratio and sometimes increase the drag coefficient (e.g., helical strake).…”

Section: Introductionmentioning

confidence: 99%

The Effect of Shifting Natural Frequency on the Reduction of Vortex-Induced Vibrations of Marine Risers

Komachi¹,

Mazaheri²,

Tabeshpour

2017

ijcoe

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Many procedures suggest for reduction of responses of riser to Vortex Induced Vibrations (VIV). Natural frequencies of marine risers is an important parameter that can affect the responses of riser to VIV. Change of riser properties such as top tension and bending stiffness can alter natural frequencies. In this study effects of riser specifications on the responses and fatigue damage of marine risers were investigated analytically and numerically. For numerically analysis 2D wake-structure coupled model is used for modeling of VIV of riser in two directions of Cross Flow (CF) and In Line (IL). The wake dynamics, including IL and CF vibrations, is represented using a pair of non-linear Van der Pol equations that solved using modified Euler method. The Palmgren-Miner Rule is used for evaluation of fatigue damage. Riser of Amir-Kabir semisubmersible placed in Caspian sea is used for case study. Because VIV is self-limiting, it is showed that lower modes have lower curvature, that in some cases this is lead to lesser stress and also fatigue damage. The results show that for tension dominant modes of vibration, natural frequencies was increased with top tension and for a certain Strouhal frequency, dominant modes of vibration was reduced which leads to reduction of stress and fatigue damage. The results show that stress and fatigue damage increased with module of elasticity of riser and reduction of this leads to reducing of stress and fatigue damage. Therefore suitable procedure for reduction of VIV responses of riser should be selected based on the current velocity.

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Reduction of flow-induced forces on a circular cylinder using a detached splitter plate

Cited by 197 publications

References 9 publications

Vortex shedding effects in grid-generated turbulence

Vortex shedding effects in grid-generated turbulence

Investigation of Effect of Boundary Layer on Flow Structure Around a Cylinder with a Strip

The Effect of Shifting Natural Frequency on the Reduction of Vortex-Induced Vibrations of Marine Risers

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