Transient heat transfer characteristics of swirling and non-swirling turbulent impinging jets

İkhlaq, Muhammad; Al-Abdeli, Yasir M.; Khiadani, Mehdi

doi:10.1016/j.expthermflusci.2019.109917

Cited by 10 publications

(3 citation statements)

References 34 publications

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“…Impinging jets are extensively utilized in numerous thermal devices and industrial processes, such as heating, cooling and drying for their effective heat and mass transfer characteristics. Few applications are drying in the paper industry, cooling and heating in the food industry, cooling of gas turbine blades and electronic devices 1–4 . Higher convective rates of impinging jets ensure rapid cooling or heating of local heat transfer zones.…”

Section: Introductionmentioning

confidence: 99%

“…Few applications are drying in the paper industry, cooling and heating in the food industry, cooling of gas turbine blades and electronic devices. [1][2][3][4] Higher convective rates of impinging jets ensure rapid cooling or heating of local heat transfer zones. Single jets have shown their potential for many industrial applications, but most of the industrial applications require adding or removing heat from large areas.…”

Section: Introductionmentioning

confidence: 99%

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Thermal characteristics of arrays of swirling impinging jets: Effect of Reynolds number, impingement distance, and jet‐to‐jet separation

et al. 2022

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This paper numerically investigates both the inline and staggered arrays of circular multiple swirling air jets that impinge perpendicularly onto a smooth flat surface. The simulations were conducted for various flow and geometric parameters, such as Reynolds number (Re = 11,600, 24,600, and 35,000), jet‐to‐surface distance (H/D = 1, 2, 3, and 4), jet‐to‐jet separation distance (Z/D = 1.5, 3.0, and 4.5) and swirl numbers (S = 0, 0.3, and 0.75), where D is the nozzle diameter. For S = 0.75, a strong recirculation develops due to the vortex breakdown, depends on Z/D, around the axis and near the wall. The extent of the recirculation is larger for the staggered array. Intense heat transfer is anticipated at strong swirl and close impingement cases with the expense of uniformity; whereas a relatively even heat transfer is observed for larger impingements. The increase in jet‐to‐jet separation enhances the overall cooling effect and the staggered configuration of nozzles gives better performance. It appears that both the crossflow and turbulence around the periphery of each jet predominantly govern the heat transfer characteristics. The enhancement of heat transfer occurs for increasing Re, and the overall Nusselt number (Nu) prediction is scaled by Ren, with n dependent on S. Finally a correlation is developed for the average Nusselt number to relate different control parameters.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Thermal characteristics of arrays of swirling impinging jets: Effect of Reynolds number, impingement distance, and jet‐to‐jet separation

et al. 2022

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“…They also concluded that the recirculation strength of a swirling jet is larger than that of a non-swirling jet. Ikhlaq et al (2019) compared both swirling and non-swirling transient flow development. Liang Xu et al (2021) proposed a new swirling impingement cooling jet with four inner spiral grooves in internal threads.…”

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On the impingement of heat transfer using swirled air jets

Kotb

Askar²,

Saad³

2023

Front. Mech. Eng.

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Experimental analyses were conducted under identical experimental conditions on the heat transfer between a constant heat flux flat plate and a round air jet for both conventional and swirled jets. Vane-type swirl generators inserted at the nozzle exit were used to produce a swirl. The experimental measurements were performed at a fixed Reynolds number value (Re = 23,000) calculated on the jet tube’s inside diameter. A comparison between conventional air jets and swirl jets with swirl numbers of S = 0, 0.19, 0.42, and 0.72 was presented for the different nozzle-to-plate spacings Z/D = 2, 6, and 10. The results show that heat transfer to the plate decreases when the nozzle-to-plate distance increases. In addition, increasing the swirl number S increases heat transfer uniformity but decreases global heat transfer. At the low plate-to-jet distance Z/D = 2, the point of maximum heat transfer is shifted to a radial position depending on the swirl number. Also, for both Z/D = 6 and 10, the stagnation point and stagnation region heat-transfer enhances only for swirl numbers 0 and 0.19.

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