Flow field and thermal behaviour in swirling and non-swirling turbulent impinging jets

Ahmed, Zahir U.; Al-Abdeli, Yasir M.; Guzzomi, Ferdinando

doi:10.1016/j.ijthermalsci.2016.12.013

Cited by 58 publications

(24 citation statements)

References 51 publications

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“…This may be because the large separation allows the jet spreading angle to increase (the stagnation area is smaller for H/D = 4, see Figure 12, and the secondary peak in the Nusselt occurs at earlier r/D distance) and thus the heat transfer, as seen in contours levels of Figure 11(a,b). When the swirl number is increased, our results agree with those reported in Ahmed et al (2017), where a transition is observed at S = 0.45. The experimental approach described in Nuntadusit et al (2012) led to equivalent results.…”

Section: Resultssupporting

confidence: 91%

“…This can be observed more clearly in Figure 10, where for instance φ = 8% is shown since all φ behave similarly. The increase of Nu as S is increased is due to the fact that the swirl enhances turbulence and mixing, as explained in Ahmed et al (2017). This effect is found in the present simulations as shown in the turbulence intensity contours in Figure 11 (left column is H/D = 2).…”

Section: Resultssupporting

confidence: 79%

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Computational study of the application of Al₂O₃ nanoparticles to forced convection of high-Reynolds swirling jets for engineering cooling processes

Granados-Ortiz

Leon-Prieto

Ortega-Casanova

2020

Engineering Applications of Computational Fluid Mechanics

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Section: Resultssupporting

confidence: 91%

Section: Resultssupporting

confidence: 79%

Computational study of the application of Al₂O₃ nanoparticles to forced convection of high-Reynolds swirling jets for engineering cooling processes

Granados-Ortiz

Leon-Prieto

Ortega-Casanova

2020

Engineering Applications of Computational Fluid Mechanics

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“…In some cases, the grooves were cut on the inner side of jet with different twisting angles to rotate the outlet flow of fluid. The effects of swirling jets on the flow and heat transfer of fluid were investigated by many authors [20][21][22]. The study of previous works on the effects of swirling jet on the flow and heat transfer of fluid led the authors to propose the idea of using swirling exhaust plume to disperse the pollutant.…”

Section: Introductionmentioning

confidence: 99%

Desirable effects of cutting grooves on inner side of small cooling tower on reduction in ground level pollutant concentration

Sedighi

Deldoost

Bazargan

2020

J Braz. Soc. Mech. Sci. Eng.

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The pollutant dispersion from a small cooling tower is numerically investigated in the current study. The behavior of exhaust plume from a grooved cooling tower is studied to control the dispersion of pollutant by swirling the plume. The pollutant concentration, i.e., mass of pollutant per unit mass of the mixture, and the plume rise, i.e., the geometric loci of the highest pollutant concentration points at each flow cross sections downstream of cooling tower, are investigated as significant parameters in the problem of pollutant dispersion from sources of air pollution. The various ways by which the counterrotating vortex pair as well as swirling plume affect the behavior of outflow from source of air pollution are investigated. An innovative structure for inner side of cooling tower by cutting the angular grooves is proposed in this article for reduction in pollutant concentration on the ground level and moving the plume rise to the higher altitude. The results indicate that the minimum value of pollutant concentration on the ground level is obtained by applying parallel grooves with respect to the axis of the cooling tower and the plume rise occurs in a higher altitude by increasing in the angle of the grooves. The physics of the outflow from the tower is investigated to examine the effects of the grooves angle on the path of plume and dispersion of pollutant.

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“…For the swirling impinging jet, Bakirci et al [ 20 ] found that increasing the helical angle can increase the uniformity of radial heat transfer on the plate surface. Ahmed et al [ 21 , 22 , 23 , 24 ] studied the impingement pressure, flow, and heat transfer characteristics of swirling and non-swirling flows. The results showed that the pressure coefficient at the stagnation point is the same as that of non-swirling flow for the low-intensity swirling flow, and has a maximum value.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Swirling Impinging Jet Issuing from a Threaded Hole under Inclined Condition

Xiong

et al. 2019

Entropy

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There are some inclined jet holes in the cooling structure of the leading edge region of gas turbine blades. In order to improve the cooling effect of traditional round holes, this paper proposes to replace the round holes with threaded holes, and studies the complex flow and heat transfer performance of the swirling impinging jet (SIJ) issuing from the 45° threaded holes in the inclined condition by numerical simulation. The influencing factors include jet inclination angle α (45°–90°), jet-to-plate distance (H/d = 2, 4, 6), and Reynolds number (6000–24,000). The results show that the inclination angle and jet-to-plate distance have a great influence on the size, shape, and position of vortices in the jet space, while the Reynolds number has little effect on the vortices. In the inclined state, the impinging cooling effect of the swirling impinging jet is better than that of the circular impinging jet (CIJ), both heat transfer coefficients will degrade significantly when the inclination angle is 45°. When the inclination angle is greater than 45°, compared with the round hole, the enhanced heat transfer region for the swirling jet is in the region of r/d < 3, while both of the Nusselt numbers in the wall jet region are weak, with a value of just 20. At the same time, with the increasing of the inclination angle (α > 45°), the average Nusselt number on target surface holds a constant value. Under the inclined conditions, the heat transfer coefficient on the target surface for the swirling jet is increased totally with the increasing of the Re, but when the Re is larger than 18,000, the rate of enhanced heat transfer gradually weakens.

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Flow field and thermal behaviour in swirling and non-swirling turbulent impinging jets

Cited by 58 publications

References 51 publications

Computational study of the application of Al₂O₃ nanoparticles to forced convection of high-Reynolds swirling jets for engineering cooling processes

Computational study of the application of Al₂O₃ nanoparticles to forced convection of high-Reynolds swirling jets for engineering cooling processes

Desirable effects of cutting grooves on inner side of small cooling tower on reduction in ground level pollutant concentration

Numerical Simulation of Swirling Impinging Jet Issuing from a Threaded Hole under Inclined Condition

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Flow field and thermal behaviour in swirling and non-swirling turbulent impinging jets

Cited by 58 publications

References 51 publications

Computational study of the application of Al2O3 nanoparticles to forced convection of high-Reynolds swirling jets for engineering cooling processes

Computational study of the application of Al2O3 nanoparticles to forced convection of high-Reynolds swirling jets for engineering cooling processes

Desirable effects of cutting grooves on inner side of small cooling tower on reduction in ground level pollutant concentration

Numerical Simulation of Swirling Impinging Jet Issuing from a Threaded Hole under Inclined Condition

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Computational study of the application of Al₂O₃ nanoparticles to forced convection of high-Reynolds swirling jets for engineering cooling processes

Computational study of the application of Al₂O₃ nanoparticles to forced convection of high-Reynolds swirling jets for engineering cooling processes