Experimental study on heat transfer characteristics in a ribbed channel with dimples, semi-spherical protrusions, or oval protrusions

Jang, Han Na; Park, Jung Shin; Kwak, Jae Su

doi:10.1016/j.applthermaleng.2017.12.030

Cited by 29 publications

(9 citation statements)

References 25 publications

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“…Figure 12 presents the percentage of Nu (%Nu) of the rib surface to the Nu of the channel at various Re. The %Nu is calculated using the expression (20). The Nu of the channel is the total Nu of the channel, including the rib surface.…”

Section: The Spatial Effect Of Rib In Channelmentioning

confidence: 99%

“…Augmentation of the heat transfer was observed to benefit from the dimples than rib. However, taking into account the low-pressure drop, the rib protrusion design is favorable in the experiment, according to Jang et al 20 Meanwhile, Liu et al investigated a novel groove design, a combination of cylindrical with a rounded transition that generates relatively lower pressure drop than the conventional cylindrical groove and ribbed wall. The factors influencing the thermal performance were observed among many other factors, such as vortex structures and higher velocity in the vicinity of the groove surface.…”

Section: Introductionmentioning

confidence: 99%

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Spatial effect of a vertical multi-faceted rib on thermal performance and flow characteristics in a square channel

Amir

Ir.

2022

Proceedings of the Institution of Mechanical Engineers, Part C:

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A multi-faceted vertical rib has been numerically investigated using the internal flow of rib in a rectangular channel method under turbulent flow for 17,000 < Re < 27,000. The vertical rib that can be encountered inside porous media design often creates a persisting issue of high-pressure drop. The challenge frequently intensifies, mainly when a two-phase state heat transfer is introduced inside the porous media. The vertical multi-faceted rib models the various surfaces often encountered inside the porous media. The effect of blockage ratio on the flow characteristics and thermal performance is observed. The results are compared to the more conventional circular rib, equal in surface area to the multi-faceted rib. The multi-faceted rib yields a higher average Nusselt number of approximately 33% and contributes to the higher average Nusselt number of the channel. The multi-faceted rib channel has a better thermal performance factor, in average of approximately 13% higher and lower pressure drop than the circular rib channel. The advantage of the multi-faceted rib is attributed to, surprisingly, the poor flow attachment on the rib surface, which results in a low Cf/ f ratio. Consequently, the multi-faceted rib suffers from very low velocity on the downstream rib surface. Ultimately, the spatial effect of the rib inside the square channel can be evaluated using the Cf/ f ratio, which takes into account the rib surface and channel walls. In the quasi two-phase state, the circular rib is observed to provide a more favorable condition for latent heat transfer under extreme condition investigated.

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Section: The Spatial Effect Of Rib In Channelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Spatial effect of a vertical multi-faceted rib on thermal performance and flow characteristics in a square channel

Amir

Ir.

2022

Proceedings of the Institution of Mechanical Engineers, Part C:

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“…It has been observed that combination of ribs and dimples resulted in higher heat transfer augmentation as well as higher thermal hydraulic performance as compared to ribs alone & dimple alone. Jang et al (2017) [23] studied heat transfer augmentation of a ribbed channel using dimple and protrusions of various shapes. The tested Reynolds numbers based on the channel hydraulic diameter are 30,000, 50,000 and 70,000.…”

Section: Configurationsmentioning

confidence: 99%

A Review of Heat Transfer and Pressure Loss Characteristics Through Convective Cooling Method for Gas Turbine Thermal Management

Bihari¹,

Bok²

2019

IJEAST

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Elevated temperatures in gas turbine operation exceeds the allowable temperature of the metal alloys used for turbine blades and combustor liners. Thus effective cooling strategies must be implement to ensure safe and efficient operation of gas turbines. Heat transfer enhancement can be achieved by increasing either the surface area or the heat transfer coefficient. Flow turbulence promoters such as ribs, dimples and protrusions induce a disturbance to the flow boundary layer. This lead to a regular separation and re-attachment of the near wall flow field, thus increasing the heat transfer coefficient. A number of geometric parameters like channel aspect ratio, rib-configurations, rib-orientation, blockage ratio, rib spacing, dimples and protrusions shape; depth and height have been investigated for cooling channels. The present study is aimed to review the investigation of these parameters on the heat transfer and pressure drop characteristics of cooling channels incorporated with turbulence promoters found in backside cooling of gas turbine combustor liner and internal cooling of turbine blades.

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“…It should be noted that in addition to the benefits of using these methods to increase the turbulence transport and heat transfer rate in the stream, there may be some disadvantages such as the pressure drop which is an important parameter [10], because the thrust level of the air breathing propulsion systems directly depends on the pressure drop and increasing the total pressure drop corrupts the engine performance. Different rib configurations are the most effective way for the heat transfer enhancement [11][12], sometimes may be used beside the other techniques [13][14]. It has been illustrated that the high-performance heat transfer improvement can be obtained by using the wavy walls while with lower pressure drops [15][16].…”

Section: Introductionmentioning

confidence: 99%

Using Wavy Fuel Surface to Improve the Performance of the Solid Fuel Ramjets

Reyhani

Tahsini

2022

Propellants Explo Pyrotec

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This paper introduces a new idea to augment the fuel regression rate in solid fuel ramjets. The heat transfer rate from the reacting flow field into the surface of the solid fuel grain determines directly its regression rate in this propulsion system, which is very low in comparison with solid rocket motors leads the low thrust levels. This innovative simple practical method is based on the geometrical treatment of the fuel grain, making the smooth ribs as a wavy surface, to increase the turbulence and the heat transfer rate into the evaporating surface where the fuel flow rate is determined. The finite volume solver of the turbulent reacting compressible flow is developed to study the flow field where the burning rate is computed using the conjugate heat transfer for the solid fuel. The influence of the amplitude and the period of the cosine function as the fuel surface geometry are investigated on the regression rate, and it is shown that the amplitude is more effective, and utilizing such surface treatments helps to augment considerably the fuel average regression rate.

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Experimental study on heat transfer characteristics in a ribbed channel with dimples, semi-spherical protrusions, or oval protrusions

Cited by 29 publications

References 25 publications

Spatial effect of a vertical multi-faceted rib on thermal performance and flow characteristics in a square channel

Spatial effect of a vertical multi-faceted rib on thermal performance and flow characteristics in a square channel

A Review of Heat Transfer and Pressure Loss Characteristics Through Convective Cooling Method for Gas Turbine Thermal Management

Using Wavy Fuel Surface to Improve the Performance of the Solid Fuel Ramjets

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