Fluid Flow in a 180 Deg Sharp Turning Duct With Different Divider Thicknesses

Liou, Tong‐Miin; Tzeng, Yaw-Yng; Chen, Chung-Chu

doi:10.1115/98-gt-189

Cited by 17 publications

(4 citation statements)

References 6 publications

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“…Only a few studies focused on the effect of controllable parameters on the structure of the flow. Liou et al (1999Liou et al ( , 2000 experimentally showed that the divider thickness (the thickness of the structure between the inflow and outflow channels) mainly influenced the intensity and uniformity of turbulence.…”

Section: Introductionmentioning

confidence: 99%

Linear stability of confined flow around a 180-degree sharp bend

et al. 2017

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This study seeks to characterise the breakdown of the steady 2D solution in the flow around a 180-degree sharp bend to infinitesimal 3D disturbances using a linear stability analysis. The stability analysis predicts that 3D transition is via a synchronous instability of the steady flows. A highly accurate global linear stability analysis of the flow was conducted with Reynolds number $Re<1150$ and bend opening ratio (ratio of bend width to inlet height) $0.2\leq\beta\leq5$. This range of $Re$ and $\beta$ captures both steady-state 2D flow solutions as well as the inception of unsteady 2D flow. For $0.2\leq\beta\leq1$, the 2D base flow transitions from steady to unsteady at higher Reynolds number as $\beta$ increases. The stability analysis shows that at the onset of instability, the base flow becomes three-dimensionally unstable in two different modes, namely spanwise oscillating mode for $\beta=0.2$, and spanwise synchronous mode for $\beta \geq 0.3$. The critical Reynolds number and the spanwise wavelength of perturbations increase as $\beta$ increases. For $1<\beta\leq2$ both the critical Reynolds for onset of unsteadiness and the spanwise wavelength decrease as $\beta$ increases. Finally, for $2<\beta\leq5$, the critical Reynolds number and spanwise wavelength remain almost constant. The linear stability analysis also shows that the base flow becomes unstable to different 3D modes depending on the opening ratio. The modes are found to be localised near the reattachment point of the first recirculation bubble

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Section: Introductionmentioning

confidence: 99%

Linear stability of confined flow around a 180-degree sharp bend

et al. 2017

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“…The cooling air flows through a complicated serpentine passage inside the blade that comprises of several channels along the blade height with the adjacent channels connected by sharp 180 • bends. Many other applications such as the hot gas manifold of the space shuttle main engine power head (Kwak, 1986) and ventilation piping systems (Liou, 1999) involve two adjacent ducts connected by a 180 • bend. The space constraints in coolant blade passages dictate a small radius of curvature for the 180 • turn, often smaller than the hydraulic diameter.…”

Section: Introductionmentioning

confidence: 99%

“…Flow fields in such sharp 180 • bends comprise of the turning geometry: induced secondary flow, flow separation, re-circulation, and reattachment. This results in noticeable effects on the pressure loss and non-uniformity in heat transfer distributions (Liou, 1999). Hence, the design of the cooling passages involving sharp 180 • bends requires detailed knowledge of the flow resistances offered by the cooling passages.…”

Section: Introductionmentioning

confidence: 99%

“…They concluded that both the channel aspect ratio and turn clearance have an important influence on the pressure drop characteristics of two-pass smooth rectangular channels. Liou et al (1999) investigated the effect of divider wall thickness on the fluid flow in a two-pass smooth square duct with a 180 • straight corner turn. They found that the divider wall thickness has profound effects on the flow features inside and immediately after the turn.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Pressure Drop Distribution in Smooth and Rib Roughened Square Channel with Sharp 180° Bend in the Presence of Guide Vanes

Rao.D

Prabhu

2004

International Journal of Rotating Machinery

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An experimental investigation is carried out to study the effect of several turn treatments like single guide vane (short and long) and multiple guide vanes on the pressure drop distribution in smooth and rib roughened square channels with a sharp 180 • bend. The sharp 180 • turn is obtained by dividing a rectangular passage into two square channels using a divider wall with a rounded tip at the location where the flow negotiates the turn. In rib roughened channels, ribs are configured on the top and bottom surfaces in a symmetric arrangement with an angle of 90 • to the mainstream flow. Rib height-to-hydraulic diameter ratio (e/D) is maintained constant at 0.14 with a constant pitch-to-rib height ratio (P/e) of 10. The pressure drop distribution normalized with the mainstream fluid dynamic pressure head is presented for the outer surfaces. Results suggest that 90 • multiple guide vanes result in the decrease of overall pressure drop by around 40% in smooth square channels. However, a reduction in overall pressure drop by only 15% is achievable through guide vanes in rib roughened square channels.

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Thermo-fluid-dynamic analysis of the flow in a rotating channel with a sharp “U” turn

2012

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Infrared thermography has been employed to carry out a detailed convective heat transfer measurements at Re = 20,000 in a two-pass square channel both for the static case (absence of channel rotation) and for the rotating case (Ro = 0.3). At the same time, the main and secondary flow fields have been measured by means of particle image velocimetry with the aim to investigate how the flow behavior affects the local distributions of the convective heat transfer coefficient for the two cases. The normal-towall velocity component (w) and the turbulent kinetic energy, both measured close to the heat exchanging wall, have been used to formulate an empirical heat transfer correlation within an attempt to identify the role performed by these two quantities on the convective heat transfer coefficient distributions. The latter ones have been reported in terms of normalized Nusselt number (Nu/Nu*) maps, where Nu* is the Nusselt number evaluated with the classical Dittus-Bölter correlation.

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Fluid Flow in a 180 Deg Sharp Turning Duct With Different Divider Thicknesses

Cited by 17 publications

References 6 publications

Linear stability of confined flow around a 180-degree sharp bend

Linear stability of confined flow around a 180-degree sharp bend

Pressure Drop Distribution in Smooth and Rib Roughened Square Channel with Sharp 180° Bend in the Presence of Guide Vanes

Thermo-fluid-dynamic analysis of the flow in a rotating channel with a sharp “U” turn

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