Experimental investigation of fluctuating forces exerted on a cylindrical tube (Reynolds numbers from 3000 to 30 000)

Tadrist, H.; Martin, R.; Tadrist, Lounès; Seguin, P.

doi:10.1063/1.857804

Cited by 15 publications

(5 citation statements)

References 16 publications

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“…[26], the inability of the two-dimensional method used to model three-dimensional turbulence is part of the reason. Also, it is stated [27,28] that the measured fluctuating forces are considerably affected by many factors, such as aspect ratio, blockage, turbulence intensity, tube end boundaries, etc.…”

Section: Resultsmentioning

confidence: 99%

The Interaction of Porous Material Coating With the Near Wake of Bluff Body

Liu¹,

Wei²,

2013

Journal of Fluids Engineering

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The flow around a circular cylinder with porous material coating (PMC) is numerically investigated based on unsteady Reynolds-averaged Navier-Stokes (URANS) method at subcritical Reynolds number. The results are compared with some available results in the open literature. The interaction of PMC with the near wake of a circular cylinder such as streamline, vorticity field, and shear stress are studied in detail. Subsequently, the fluctuation forces and velocity distribution in the boundary layer are analyzed and the effect of various thicknesses of PMC is investigated. The numerical results reveal that PMC has prominently modified the flow characteristic of the near wake of circular cylinder and significantly mitigated the fluctuations of aerodynamic forces from two aspects of frequency and amplitude. It means that the vortex shedding from the bluff body is suppressed. It also is found that the thickness of the PMC is a sensitive parameter to the aerodynamic forces and velocity distribution in the boundary layer. Furthermore, the mean drag can be reduced to a certain extent when the thickness is appropriate. It is expected that the modification of flow characteristic and aerodynamic forces is closely related to the flowinduced noise reduction. Those results will be helpful to understand the mechanism of flow control on bluff body flow by using porous material coating and accumulate meaningful information for further industrial application.

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Section: Resultsmentioning

confidence: 99%

The Interaction of Porous Material Coating With the Near Wake of Bluff Body

Liu¹,

Wei²,

2013

Journal of Fluids Engineering

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“…Schewe's (1983) measurements give lower fluctuating lift values, which is to be expected, since his lift coefficients are based on force measurements using the entire cylinder length (1OD) and will hence be affected by the limited spanwise correlation of vortex shedding. Tadrist et al (1990) results are also obtained from the whole span (12.5 < L I D < 30). Their results using different cylinders, of which only samples are shown here, are somewhat scattered.…”

Section: Discussionmentioning

confidence: 99%

“…Although the accuracy of their measurements is not given, the results imply that the fluctuating lift coefficient grows much slower with increasing Reynolds number than predicted by a twodimensional numerical simulation. Measurements by Tadrist et al (1990), using aspect ratio LID = 12.5-30, show that there is a sharp reduction in the fluctuating lift for Reynolds numbers below lo4, down to the lower boundary of their measured range (Re = 3000).…”

Section: Introductionmentioning

confidence: 96%

Aspect ratio and end plate effects on vortex shedding from a circular cylinder

1992

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Aspect ratio effects on the vortex shedding flow from a circular cylinder have been studied by using moveable end plates. Experiments were carried out to measure fluctuating forces, shedding frequency and spanwise correlation whilst varying end plate separation and Reynolds number. The aspect ratio (0.25–12) was found to have a most striking effect on the fluctuating lift. Within a certain range of Reynolds number an increase of the sectional fluctuating lift was obtained for reduced aspect ratio, and showed a maximum for an aspect ratio of 1, where the fluctuating lift could be almost twice the value for very large aspect ratios. This increase of the lift amplitude was found to be accompanied by enhanced spanwise correlation of the flow. The measurements were carried out over the Reynolds number range 8 × 103 < Re < 1.4 × 105. The strong increase in fluctuating lift with small aspect ratio did not occur at the lower and upper boundaries of this range. In the lower Reynolds number range (Re < 2 × 104) the trend could be reversed, i.e. the fluctuating lift decreased with decreasing aspect ratio. Also, with small aspect ratio, a shedding breakdown was found in the upper Reynolds number range (Re = 1.3 × 105). The main three-dimensional feature observed was a spanwise variation in the phase of vortex shedding, accompanied by amplitude modulation in the lift signal. However, the level of three-dimensionality can be reduced by using a small aspect ratio. Three-dimensional vortex shedding features are discussed and comparison of the results with those from both two-dimensional numerical simulations and other experiments using large aspect ratios are presented.

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“…lift coefficient by So and Savkar, 1981 is around 1.0, which is larger than that computed in this study. It is stated (Tadrist et al, 1990;Lam et al, 2003) that the measured fluctuating forces are considerably affected by many factors, such as aspect ratio, blockage, turbulence intensity, tube end boundaries, etc. In all of the following study the mesh density around the cylinder surface is kept the same as the fine mesh of the single cylinder case.…”

Section: Validation Of the Modelmentioning

confidence: 99%