Flow over a system of several ribs under conditions of high free-stream turbulence

Терехов, В. И.; Yarygina, Nadezhda I.; Smulsky, Ya. I.

doi:10.1134/s0869864306030036

Cited by 4 publications

(3 citation statements)

References 8 publications

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“…It is shown in studies of separated flows [22][23][24][25][26][27]35,36,[39][40][41][42][43][44][45][46][47] that turbulence of the incoming flow has a more noticeable effect on them than on the boundary layers. Moreover, it is not correlated with high turbulence induced in the shear layer of the separated flow [26].…”

Section: Highly-turbulent Flow Around a Backward-facing Step And A Single Ribmentioning

confidence: 99%

“…The ribs can also be set at an angle to the flow. Flow visualization [40] showed that in the case of a low-turbulent flow around an assembly of three or more high ribs (H = 60 mm), a highly unstable flow can be seen in the second cell; it is associated with mass suction from next cell because of the low pressure behind the second rib and a reverse flow over the third rib (Figure 22). Thus, a multi-ribbed structure can be regarded as a feedback system, when the flow and heat transfer in the cell in front depends on how many cells are located after it.…”

Section: Heat Transfer In the Ribs Systemmentioning

confidence: 99%

“…Figure23. Distribution of the coefficient averaged heat transfer coefficient over the cell surface when flowing around from two to five fins (light symbols-Tu0 = 1.5%; dark ones-Tu0 = 15%)[40].…”

mentioning

confidence: 99%

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Heat Transfer in Highly Turbulent Separated Flows: A Review

Терехов

2021

Energies

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The study of flows with a high degree of turbulence in boundary layers, near-wall jets, gas curtains, separated flows behind various obstacles, as well as during combustion is of great importance for increasing energy efficiency of the flow around various elements in the ducts of gas-dynamic installations. This paper gives some general characteristics of experimental work on the study of friction and heat transfer on a smooth surface, in near-wall jets, and gas curtains under conditions of increased free-stream turbulence. Taking into account the significant effect of high external turbulence on dynamics and heat transfer of separated flows, a similar effect on the flow behind various obstacles is analyzed. First of all, the classical cases of flow separation behind a single backward-facing step and a rib are considered. Then, more complex cases of the flow around a rib oriented at different angles to the flow are analyzed, as well as a system of ribs and a transverse trench with straight and inclined walls in a turbulent flow around them. The features of separated flow in a turbulized stream around a cylinder, leading to an increase in the width of the vortex wake, frequency of vortex separation, and increase in the average heat transfer coefficient are analyzed. The experimental results of the author are compared with data of other researchers. The structure of separated flow at high turbulence—characteristic dimensions of the separation region, parameters of the mixing layer, and pressure distribution—are compared with the conditions of low-turbulent flow. Much attention is paid to thermal characteristics: temperature profiles across the shear layer, temperature distributions over the surface, and local and average heat transfer coefficients. It is shown that external turbulence has a much stronger effect on the separated flow than on the boundary layer on a flat surface. For separated flows, its intensifying effect on heat transfer is more pronounced behind a rib than behind a step. The factor of heat transfer intensification by external turbulence is most pronounced in the transverse cavity and in the system of ribs.

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Section: Highly-turbulent Flow Around a Backward-facing Step And A Single Ribmentioning

confidence: 99%

Section: Heat Transfer In the Ribs Systemmentioning

confidence: 99%

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Heat Transfer in Highly Turbulent Separated Flows: A Review

Терехов

2021

Energies

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The Effect of Longitudinal Pressure Gradient on Heat Transfer in a Separated Flow Behind a Sudden Expansion of the Channel

Терехов

Dyachenko

Smulsky

2020

Heat Transfer Engineering

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Two-Dimensional Flow Passage Through a Hot Ribbed Channel: Effect of First Rib Width

Omari

Mataoui

Salem

2018

Journal of Thermal Science and Engineering Applications

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This work investigates numerically by finite volume method using Low k–ω model, the forced turbulent convection through a channel roughened by seven heated ribs arranged transversely. These ribs of rectangular cross section have a blocking ratio H/h = 10 and pitch ratio λ/h = 3. The modeling the problem parameters are Reynolds number, ranging from 5480 to 68500, and the width of the first rib L1 ranging from 0.5h to 15h. The objective of this study is to look for the width of the first rib L1 which induces the best heat transfer. The flow configurations of identical ribs from the first one generate a large eddy spreading along the top of the two first ribs, blocking the flow of the first cavity. The widening of the first rib may solve this problem. This flow configuration is required in several engineering applications necessitating the flow periodicity starting from the first cavity. The streamlines show that the first rib acts as a forward facing step when L1 > 5h. The effect of the width of the first rib is highlighted by velocity, pressure, turbulent kinetic energy and temperature profiles. Nusselt number distributions confirm that the widening of the heated surface is not recommended for improving heat transfer in spite of flow periodicity in all cavities (roughness d-type). The best improvement in heat transfer of 18%, compared to a smooth wall is obtained for thinnest first rib of L1/h = 0.5. However, this configuration provides a minor heat exchange at the first pitch and the second rib, which might be a disadvantage for the material structure.

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Flow over a system of several ribs under conditions of high free-stream turbulence

Cited by 4 publications

References 8 publications

Heat Transfer in Highly Turbulent Separated Flows: A Review

Heat Transfer in Highly Turbulent Separated Flows: A Review

The Effect of Longitudinal Pressure Gradient on Heat Transfer in a Separated Flow Behind a Sudden Expansion of the Channel

Two-Dimensional Flow Passage Through a Hot Ribbed Channel: Effect of First Rib Width

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