Heat transfer and entropy generation in air jet impingement on a model rough surface

Xu, Peng; Sasmito, Agus P.; Qiu, Shuxia; Mujumdar, Arun S.; Xu, Long; Geng, Liping

doi:10.1016/j.icheatmasstransfer.2016.01.007

Cited by 52 publications

(16 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, reliable reference data including entropy production maps for validation purpose are often not available in the literature, also in the case of turbulent impinging cooling. Only a few numerical studies based on RANS addressed entropy production generation mechanisms in turbulent impinging cooling, e.g., [68][69][70]. Reliable scale-resolved simulations like LES or DNS including a second law analysis are not reported in the literature.…”

Section: Introductionmentioning

confidence: 99%

Near-Wall Thermal Processes in an Inclined Impinging Jet: Analysis of Heat Transport and Entropy Generation Mechanisms

Ries

Klingenberg

et al. 2018

Energies

View full text Add to dashboard Cite

In this work, near-wall thermal transport processes and entropy generation mechanisms in a turbulent jet impinging on a 45 ∘ -inclined heated surface are investigated using a direct numerical simulation (DNS). The objectives are to analyze the subtle mechanisms of heat transport in the vicinity of an inclined impinged wall, to determine the causes of irreversibilities that are responsible for the reduction of performance of impingement cooling applications and to provide a comprehensive dataset for model development and validation. Results for near-wall thermal characteristics including heat fluxes are analyzed. An entropy production map is provided from the second law analysis. The following main outcomes can be drawn from this study: (1) the location of peak heat transfer occurs not directly at the stagnation point; instead, it is slightly shifted towards the compression side of the jet, while at this region, the heat is transported counter to the temperature gradient; (2) turbulent thermal and fluid flow transport processes around the stagnation point are considerably different from those found in other near-wall-dominated flows and are strongly non-equilibrium in nature; (3) heat fluxes appear highly anisotropic especially in the vicinity of the impinged wall; (4) in particular, the heated wall acts as a strong source of irreversibility for both entropy production related to viscous dissipation and to heat conduction. All these findings imply that a careful design of the impinged plate is particularly important in order to use energy in such a thermal arrangement effectively. Finally, this study confirms that the estimation of the turbulent part of the entropy production based on turbulence dissipation rates in non-reacting, non-isothermal fluid flows represents a reliable approximate approach within the second law analysis, likewise in the context of computationally less expensive simulation techniques like RANS and/or LES.

show abstract

Section: Introductionmentioning

confidence: 99%

Near-Wall Thermal Processes in an Inclined Impinging Jet: Analysis of Heat Transport and Entropy Generation Mechanisms

Ries

Klingenberg

et al. 2018

Energies

View full text Add to dashboard Cite

show abstract

“…Figure 3 clearly show the shear layer detachment at the step corner, followed by the reattachment, as well as the recirculation vortex induced in the vicinity of the step. As mentioned by [ 22 ], this effect induce a decrease of the local heat transfer. These phenomena were also observed experimentally by [ 20 ] and [ 23 ], and numerically by [ 19 ].…”

Section: Resultsmentioning

confidence: 87%

Numerical Analysis of Single Jet Impinging a Flat and Non-flat Plate

Barbosa

Teixeira

2020

Computational Science and Its Applications – ICCSA 2020

View full text Add to dashboard Cite

The complexity of the flow field and heat transfer in jet impingement has led to several studies in order to increase the processes and products performance. Jet impingement is widely implemented, since it ensures high average heat transfer coefficients and the uniformity of the temperature over the target surface. However, the flow generated depends on several parameters related to the jet flow, such as jet velocity and temperature, and the target plate geometry. Complex impinging surfaces are identified in the majority of the applications, such as reflow soldering and cooling of turbines or solar systems. To increase the process efficiency, it is important to fully understand the interactions between the jet and the target surface. Considering the interest of this field, the present study is conducted to investigate the influence of the target surface on heat transfer in a single jet impingement process. To minimize the number of experiments, decreasing time and costs, the implementation of numerical tools is fundamental. In that sense, the impingement of the hot air jet over a flat and non-flat plate was predicted numerically using the ANSYS FLUENT software. The velocity and temperature profile were analyzed and the Nusselt number were compared for both cases. The results show the complexity of the flow generated in the vicinity of the step and the changes of the jet flow structure when it impinges a complex surface.

show abstract

“…Ghadi et al [18] elucidated that pulsating flows generated larger and greater coherent vorticities than steady flows in circular impinging jets. This phenomenon resulted in higher heat transfer in pulsation flows [18,28]. Fig.…”

Section: Resultsmentioning

confidence: 96%

A detailed analysis of flow and heat transfer characteristics under a turbulent intermittent jet impingement on a concave surface

2022

View full text Add to dashboard Cite

A computational study is carried out of the three-dimensional flow field and heat transfer under a turbulent intermittent circular jet impingement on a concave surface. The control-volume procedure with the SIMPLE algorithm is employed to solve the unsteady RANS (use full form) equations. The RNG k-? model is implemented to simulate turbulence due to its success in predicting similar flows. The numerical results are validated by comparing them with the experimental data. The effects of jet Reynolds number and oscillation frequency on the flow and heat transfer are evaluated. The profiles of instantaneous and time-averaged Nusselt numbers exhibit different trends in axial (x) and circumferential (s) directions. It is found that increasing frequency from 50 to 200 Hz results in considerable time-averaged Nusselt number enhancement in both axial and curvature directions. The intermittent jet at a frequency of 200 Hz enhances the total average Nusselt number by 51.4%, 40%, and 33.7% compared to the steady jet values at jet Reynolds numbers of 10000, 23000, and 40000, respectively. In addition, a correlation for the average Nusselt number is proposed depending on the Reynolds number and the Strouhal number.

show abstract

Heat transfer and entropy generation in air jet impingement on a model rough surface

Cited by 52 publications

References 36 publications

Near-Wall Thermal Processes in an Inclined Impinging Jet: Analysis of Heat Transport and Entropy Generation Mechanisms

Near-Wall Thermal Processes in an Inclined Impinging Jet: Analysis of Heat Transport and Entropy Generation Mechanisms

Numerical Analysis of Single Jet Impinging a Flat and Non-flat Plate

A detailed analysis of flow and heat transfer characteristics under a turbulent intermittent jet impingement on a concave surface

Contact Info

Product

Resources

About