Modification of junction flows by altering the section shapes of the cylinders

Wei, Qiang; Wang, J. M.; Chen, G.; Lu, Zhiming; Bi, Wu

doi:10.1007/bf03181926

Cited by 13 publications

(5 citation statements)

References 18 publications

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“…Matsuguchi et al [9] displayed a classification map of the necklace vortex system in front of a rectangular cylinder with a width-to-height ratio w/h = 2 in the projected area. Wei et al [13] [14] experimentally observed the steady necklace vortex and unsteady oscillating vortex in front of a long cylinder with various cross section shapes including circles, rectangles and prisms. On the other hand, Okamoto et al [11] showed the existence of a necklace vortex at a high Reynolds number through wind tunnel testing of the pressure distributions and oil film patterns observed on the ground wall surface around rectangular plates with width-to-height ratios 2, 4 and 7.…”

Section: Introductionmentioning

confidence: 99%

Visualization of a Laminar Necklace Vortex System in Front of a Vertical Rectangular Plate on a Ground Wall

Nakahara¹,

Yamada

2015

JFCMV

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Various properties of a necklace vortex system formed around a rectangular plate standing vertically on a flat ground wall were investigated by visualizations produced by injecting fluorescent dye into a water channel flow. As a result, it was found that the necklace vortex pattern had three steady systems depending on the Reynolds number Reh, the relative height h/δ of the rectangular plate compared with the laminar boundary layer thickness and the aspect ratio w/h. As it is expected that the aspect ratio of the rectangular plate will typify the projected area configuration of various three-dimensional bodies, the aspect ratio is varied widely from 0.5 to 7.0. The transitional boundaries of Reh and h/δ in the 2-vortex, 4-vortex and 6-vortex systems for each aspect ratio decreased when w/h < 3.0, and increased when w/h ≥ 3.0 as w/h increased. The x-direction length of the main vortex position XV1/h was almost constant when w/h < 3.0, and decreased when w/h ≥ 3.0 as Reh increased. Then, the separation length r 1 /h increased when w/h < 3.0 and Reh < 1000, and became almost constant when w/h ≥ 3.0 and Reh ≥ 1000 as w/h and Reh increased. Moreover, the increase of r 1 /h is notably rapid when w/h < 3.0.

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Section: Introductionmentioning

confidence: 99%

Visualization of a Laminar Necklace Vortex System in Front of a Vertical Rectangular Plate on a Ground Wall

Nakahara¹,

Yamada

2015

JFCMV

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“…Wei et al [9] investigated various cylinder cross-sections, including square, circular, and rhombuses with varying leading-edge angles. Based on their findings, they concluded that the cross-section bluntness had a strong effect on the location and strength of the primary horseshoe vortex.…”

Section: Parametric Effects Geometric Parametersmentioning

confidence: 99%

“…Wei et al [9] proposed a unique solution for modifying the horseshoe vortex. Based on the knowledge that small leading-edge radii and swept leading edges lead to weaker horseshoe vortices, they placed a thin, swept, circular cylinder in front of a square cylinder such that one end of the thin cylinder was attached to the wall, and the other end was attached to the square cylinder at some distance from the wall.…”

Section: Controlling Junction Flowmentioning

confidence: 99%

Parametric Exploration of Wing–Body Junction Flow Using Computational Fluid Dynamics

Hinson

Hoffmann

2015

Journal of Aircraft

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“…2. Wei et al (2008) experimentally studied the HSVs associated with surface-mounted square-, circular-, and diamond-shaped cylinders. They found that the size and strength of the HSV and its distance from, wall shear stresses at, and pressures near the cylinder's leading edge (LE) decreased as the cylinder's geometry was modi ed from a square to a circle and a diamond with leading vertex angles of 90°, 60°, and 30°.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation on Juncture Flow Associated with a Surface-Mounted Circular Cylinder Trailed by a Backward-Facing Step

Yang

Chow

2022

Preprint

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Juncture flows associated with surface-mounted obstacles can be characterized by a U-shaped tubular vortical flow known as a horseshoe vortex (HSV). Horseshoe vortices are usually detrimental to engineering applications. Therefore, numerous studies have investigated methods for reducing HSVs’ strength. To design a suitable method for reducing HSVs’ strength, the characteristics of HSVs influenced by external boundary geometries must first be understood. Thus, we experimentally investigated a juncture flow field associated with a fundamental geometry—a circular cylinder mounted perpendicular to a plane surface—with a trailing backward-facing step representing downstream effects on upstream-formed flow structures. This setup is one of the simplest nonplanar geometries that generates flow features such as an unsteady separated shear layer that may considerably affect an HSV. We used the particle image velocimetry (PIV) and PIV-based flow visualization techniques combined with a vortex-fitting algorithm to measure the juncture flow and identify the HSV and its kinematic modes at a low Reynolds number of 1100. We compared the results obtained with and without the backward-facing step and observed that the backward-facing step increased the number and complexity of kinematic modes, i.e. the unsteadiness, of the HSV, and reduced HSV’s stretching, which resulted in an increased vortex diameter and increased circulation; that is, the strength of the HSV was enhanced by the backward-facing step.

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Modification of junction flows by altering the section shapes of the cylinders

Cited by 13 publications

References 18 publications

Visualization of a Laminar Necklace Vortex System in Front of a Vertical Rectangular Plate on a Ground Wall

Visualization of a Laminar Necklace Vortex System in Front of a Vertical Rectangular Plate on a Ground Wall

Parametric Exploration of Wing–Body Junction Flow Using Computational Fluid Dynamics

Experimental Investigation on Juncture Flow Associated with a Surface-Mounted Circular Cylinder Trailed by a Backward-Facing Step

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