An Experimental Investigation of a Turbulent Cylindrical Wall Jet Equipped with Front-Facing Step. Separation and Reattachment Properties of Wall Jet Flow.

Kozato, Yasuaki; Islam, Aminul; Imao, Shigeki; Tanaka, Toshio

doi:10.1299/jsmeb.42.355

Cited by 4 publications

(1 citation statement)

References 5 publications

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“…He confirms that when the conductivity ratio increases, average Nusselt number augments asymptotically approaching the non-conjugate value. Kozato et al, 1999); examined experimentally the case of a turbulent axisymetrical wall jet issuing from an annular nozzle impinging a forward facing step. (Anindya, 2007), investigated numerically and experimentally the effects of an impinging jet on cube-shaped buildings.…”

Section: Fig 1 the Geometry Of The Configurationmentioning

confidence: 99%

Fluid flow of a wall jet impinging a hot obstacle

Kabache

Mataoui

2015

JTST

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A numerical study is performed in order to investigate the effects of the inlet flow structure on the flow and heat transfer characteristics in the reattachment zones over open cavity. Indeed, two inlet flow configurations are tested ; a turbulent wall jet which has a particular structure with two sources of turbulence production (the first is due to the shear flow associated to the inner layer characterized by small scale and second one is of the free shear jet flow with large turbulence scales) and a free boundary layer flow .The inner region of these two flows is similar, but their external regions are extremely different. The separating and reattaching flow phenomena are of particular interest in engineering fields. The numerical results of the analyses the local convective heat transfer. The Nusselt number is more important and decreases immediately downstream the reattachment under the wall jet inlet flow. This detail may be explained from a dynamical point of view; the turbulent energy is more important but in small area around the each reattachment zone. The local Nusselt number increases when the Reynolds numbers augments. The evolution of local Nusselt , depends on incoming flow configuration. For the two configuration of incoming flow (Boundary layer or Wall jet), the distribution of mean Nusselt number is correlated according with some problem parameters.

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Section: Fig 1 the Geometry Of The Configurationmentioning

confidence: 99%

Fluid flow of a wall jet impinging a hot obstacle

Kabache

Mataoui

2015

JTST

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Numerical Study of Heat Transfer and Separated Flow over Rectangular Obstacle in Jet

Kabache

Mataoui

2014

Heat Trans. Asian Res.

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This paper is about a separated reattaching flow over a hot rectangular obstacle. Two types of incoming flow are examined in order to show the influence of the external zone of the flow on the reattachment process. It comes about due to a wall jet and a boundary layer. The inner region of these two flows is similar, but their external regions are extremely different. The separating and reattaching flow phenomena are of particular interest in engineering fields such as for an aeronautical application. Wall jet flow over an obstacle occurs in many engineering applications such as environmental discharges, heat exchangers, fluid injection systems, cooling of combustion chamber wall in a gas turbine, automobile design, and others. In electronics cooling, the prediction of the Nusselt number distribution along the obstacles is necessary before the design of the apparatus. For a heated obstacle at a constant temperature, T = 350 K and an aspect ratio of 10 (L = 10 H), the problem parameters are: (a) jet exit Reynolds number (Re) ranged from 1000 to 50000, (b) incoming flow configuration (boundary layer and wall jet). The ratio between the thickness of the nozzle (b) to the obstacle height (H) are examined simultaneously. The formulation is based on the SST k-turbulence model. The results show that the increasing of nozzle thickness; enhances the heat transfer and considerably modifies the stagnation point location. The highest incoming flow momentum provides the greatest values of average Nusselt number. Such as the boundary layer case in comparison with the wall jet cases. The average Nusselt number is correlated according to problem parameters (Nu obstacle = f (Re, b)). C⃝

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Study on the vortex-induced vibration and flow control of ribbed circular cylinder

Huang,

Yang,

Wang

et al. 2024

Physics of Fluids

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This work investigates the vortex suppression performance and mechanism of ribs on high-quality ratio cylinders. Through wind tunnel tests and numerical simulations, the surface wind pressure distribution characteristics and flow separation phenomena of different ribbed cylinders are explored, and the spanwise correlation and nonlinear vibration characteristics of vortex-induced vibrations of ribbed cylinder models are analyzed. The main conclusions are as follows: ribs change the position of the boundary layer separation point, and the difference in size of left and right separated vortices causes a pressure jump phenomenon, altering the wind pressure distribution of the segment model and reducing the wind pressure, resulting in an increase in the locked wind speed of the ribbed cylinder. Complex separated vortices form behind the ribs, affecting the size of the wake vortex and reducing the stability of the segment model at locked wind speeds. Cylinders with four ribs exhibit good vortex-induced vibration suppression performance at 0° and 45° positioning angles. In addition, the cylinder with four installed ribs cylinders exhibits two locked wind speed regions, each showing different motion states: at the primary locked wind speed, they mainly demonstrate quasi-periodic vibrations and degraded quasi-periodic vibrations, while at the secondary locked wind speed, primarily in a chaotic state dominated by high-frequency harmonic components. These research findings have significant implications for future studies and practical engineering applications.

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An Experimental Investigation of a Turbulent Cylindrical Wall Jet Equipped with Front-Facing Step. Separation and Reattachment Properties of Wall Jet Flow.

Cited by 4 publications

References 5 publications

Fluid flow of a wall jet impinging a hot obstacle

Fluid flow of a wall jet impinging a hot obstacle

Numerical Study of Heat Transfer and Separated Flow over Rectangular Obstacle in Jet

Study on the vortex-induced vibration and flow control of ribbed circular cylinder

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