Influence of turn geometry on turbulent fluid flow and heat transfer in a stationary two-pass square duct

Erelli, Ramesh; Saha, A.; Panigrahi, Pradipta Kumar

doi:10.1016/j.ijheatmasstransfer.2015.05.081

Cited by 23 publications

(12 citation statements)

References 27 publications

(36 reference statements)

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“…Before initiating the computations for a rib roughened channel, certain validation runs were carried out to find the distribution of Heat transfer coefficient for plane channel. [27]. The variations between the results become prominent behind the turn towards the outlet of the channel because now the flow conditions also depend on the width (thickness) of the divider wall.…”

Section: Validation With Experimentsmentioning

confidence: 98%

Numerical analysis of heat transfer and friction factor in two-pass channels with variable rib shapes

Rasool¹,

Qayoum²

2018

IJHT

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Present investigation deals with the analysis of heat transfer and friction factor for turbulent flow of air through a two-pass square channel, having ribs of various crosssections. The cases undertaken are numerically investigated by commercial software 'Comsol 5.2a' using Standard k-ε model. The emphasis is towards investigating the potential impact of differing the shape of ribs for a comparative roughness pitch (p/e) of 10. Four different test cases were analyzed: square, boot, trapezoidal and house rib designs for the Reynold's number range of 5000-52000. The Nusselt number results obtained were validated by comparing with the experimentally and computationally obtained data from earlier studies under similar conditions. The impact of the Reynold's number on the overall performance of various rib shapes has been also investigated. The increment in average Nusselt number over that of the conventional square rib roughened channel is 1.19 and friction factor gets lowered by a factor of 1.3 as compared to square ribs respectively. The analysis shows that characteristics of heat transfer distribution and fluid flow in between the ribs are significantly influenced due to rib design and the boot-shaped rib design shows better heat transfer and friction factor performance than conventional square ribs, and therefore guarantees an enhanced thermo-hydraulic performance.

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Section: Validation With Experimentsmentioning

confidence: 98%

Numerical analysis of heat transfer and friction factor in two-pass channels with variable rib shapes

Rasool¹,

Qayoum²

2018

IJHT

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“…Erelli et al . 14 examined four different turn geometries under three different Reynolds numbers (25,000, 35,000, and 45,000) under stationary conditions to examine the influence of the turn configuration on heat transfer and fluid flow. They used a realizable k–ε model to simulate turbulent flow and concluded that the strength of the secondary flow could cause more heat transfer in the bend region for all cases tested.…”

Section: Introductionmentioning

confidence: 99%

“…They observed significant effects of secondary flows on the heat transfer coefficient and its positive influence on the heat transfer rate impinging the surface, particularly, on the trailing face in the rotating state. Erelli et al 14 examined four different turn geometries under three different Reynolds numbers (25,000, 35,000, and 45,000) under stationary conditions to examine the influence of the turn configuration on heat transfer and fluid flow. They used a realizable k-ε model to simulate turbulent flow and concluded that the strength of the secondary flow could cause more heat transfer in the bend region for all cases tested.…”

Section: Introductionmentioning

confidence: 99%

Effect of a curved turning vane on the heat transfer and fluid flow of four-pass internal cooling channels of gas turbine blades

Pouyaei,

Kayhani,

Norouzi

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part G:

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This numerical study examined the effects of a curved turning vane on the heat transfer and pressure loss of a four-pass internal cooling channel. Three-dimensional omega-based Reynolds stress (RSM-ω) turbulence model equations were used in the computation process. Three different curved turning vane configurations were studied using a simple, without a turning vane under stationary and rotating conditions for Reynolds numbers between 20,000 and 60,000 and a rotation number of 0.042. The numerical results showed good agreement with previous experimental data. Under both stationary and rotating conditions, the curved turning vane in a hub turn reduced the pressure drop significantly compared to the conventional turning vanes. Although a curved turning vane attenuated overall heat transfer, the local heat transfer increased it in particular regions, such as the hub turn and the fourth turn of cooling passages, particularly in cases with smaller radii. Coolant flow through the hub turn of the serpentine channel can reduce recirculation, separation, and flow impingement, which are unfavorable factors of pressure loss, owing to the semi-circular configuration of the curved turning vane. Regarding the rotating conditions, four-pass channels with a smaller radius of a curved turning vane provide better overall cooling performance.

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“…The investigation of bend shape on overall heat transfer performance [11] suggests the symmetrical bulb (bend) configuration enhances the thermal performance factor by 41%. However, Erelli et al [12] study the impact of bend geometry on flow and heat transfer characteristics of a smooth U-shaped channel, indicating that better heat transfer performance is obtained when the outer wall of the bend is sharply connected without round edge and the inner wall of the bend is hemi-circular shape. A recent numerical study of secondary flow in a two-pass channel with 45 degree ribs [13] shows that the secondary flow in the second passage is strongly influenced by the upstream secondary flow generated in the bend region and the first passage.…”

Section: Introductionmentioning

confidence: 99%

Improving heat transfer performance in two-pass ribbed channel by the optimized secondary flow via bend shape modification

Gao

Zhu

et al. 2019

International Communications in Heat and Mass Transfer

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The heat transfer performance and friction loss of two-pass ribbed channels are highly influenced by the combined effect of rib orientation and bend shape. This paper, for the first time, numerically investigates this effect for four rib orientations, two rib angles and eight different bend shapes at Reynolds number of 30000. The results show that rib orientation determines the rotation direction and the transverse position of secondary flow in straight passages, while bend shape determines the delivery of upstream secondary flow and the generation of local secondary flow. The key to heat transfer enhancement in the second passage is to promote local secondary flow using energy from upstream secondary flow with the same rotation direction. The upstream secondary flow with the same rotation direction should be guided to a proper position, in order to enhance the dominant secondary flow in the second passage and reduce energy loss due to the undesirable secondary flow interaction. The impact of different bend shape on the secondary flow has been summarized. The round inner corner for the bend is preferred for the significant friction loss reduction and the excellent secondary flow energy delivery capacity. Meanwhile, the secondary flow generated by the square outer corner can significantly enhance the cooling performance at the entrance of the second passage for some certain rib orientations. An optimized combination of 60-degree rib orientation and bend shape can either thermal performance factor by 10 % in the second passage or reduce the friction loss by 22.3 % in the whole channel, compared with the existing experimental design. By contrast, it is found cooling performance and pressure loss are not sensitive to bend shape for the rib angel of 45-degree. The optimized bend shape is inspired by an intuitive visualization of secondary flow evolution, which provides insight on the geometry optimization for heat and mass transfer applications.

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Influence of turn geometry on turbulent fluid flow and heat transfer in a stationary two-pass square duct

Cited by 23 publications

References 27 publications

Numerical analysis of heat transfer and friction factor in two-pass channels with variable rib shapes

Numerical analysis of heat transfer and friction factor in two-pass channels with variable rib shapes

Effect of a curved turning vane on the heat transfer and fluid flow of four-pass internal cooling channels of gas turbine blades

Improving heat transfer performance in two-pass ribbed channel by the optimized secondary flow via bend shape modification

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