Numerical study of turbulent heat transfer in confined and unconfined impinging jets

Behnia, Masud; Parneix, S.; Shabany, Younes; Durbin, Paul A.

doi:10.1016/s0142-727x(98)10040-1

Cited by 268 publications

(182 citation statements)

References 21 publications

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“…Experimental data in the literature describing the heat transfer for impinging jets on a flat plate can show relatively large scatter (20 − 30%), see data [10][11][12][13][14][15][16] . The discrepancies in the available data can lie in slightly different geometrical configurations, boundary conditions, as well as in the experimental method itself and its accuracy.…”

Section: Experimental Methodsmentioning

confidence: 99%

Heat transfer measurements and CFD simulations of an impinging jet

Petera

Dostál

2016

EPJ Web of Conferences

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Abstract. Heat transport in impinging jets makes a part of many experimental and numerical studies because some similarities can be identified between a pure impingement jet and industrial processes like, for example, the heat transfer at the bottom of an agitated vessel. In this paper, experimental results based on measuring the response to heat flux oscillations applied to the heat transfer surface are compared with CFD simulations. The computational cost of a LES-based approach is usually too high therefore a comparison with less computationally expensive RANS-based turbulence models is made in this paper and a possible improvement of implementing an anisotropic explicit algebraic model for the turbulent heat flux model is evaluated.

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Section: Experimental Methodsmentioning

confidence: 99%

Heat transfer measurements and CFD simulations of an impinging jet

Petera

Dostál

2016

EPJ Web of Conferences

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“…The authors found that the constitutive relationship of the nonlinear models including k-ε and k-ω were shown to be dominated by the linear part, and also stated that both the linear and non-linear turbulence models can be used for impinging jet predictions with reasonable success. A hybrid two-equation/RSM model named f v  2 turbulence model developed by Durbin (1991) was shown to give excellent results, see Behnia et al (1998Behnia et al ( , 1999. In the f v  2 model, the fluctuating velocity component normal to streamline is used instead of k in a linear eddy viscosity formulation, so that overproduction of k is claimed to be suppressed.…”

Section: Impinging Jetmentioning

confidence: 99%

Experimental and numerical investigations of a ventilation strategy – impinging jet ventilation for an office environment

Chen¹

2014

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A well-functioning, energy-efficient ventilation system is of vital importance to offices, not only to provide the kind of comfortable, healthy indoor environment necessary for the well-being and productive work performance of occupants, but also to reduce energy use in buildings and the associated impact of CO 2 emissions on the environment. To achieve these goals impinging jet ventilation has been developed as an innovative ventilation concept.In an impinging jet ventilation system, a high momentum of air jet is discharged downwards, strikes the floor and spreads over it, thus distributing the fresh air along the floor in the form of a very thin shear layer. This system retains advantages of mixing and stratification from conventional air distribution methods, while capable of overcoming their shortcomings.The aim of this thesis is to reach a thorough understanding of impinging jet ventilation for providing a good thermal environment for an office, by using Computational Fluid Dynamics (CFD) supported by detailed measurements. The full-field measurements were carried out in two test rooms located in a large enclosure giving relatively stable climate conditions. This study has been divided into three parts where the first focuses on validation of numerical investigations against measurements, the second addresses impacts of a number of design parameters on the impinging jet flow field and thermal comfort level, and the third compares ventilation performance of the impinging jet supply device with other air supply devices intended for mixing, wall confluent jets and displacement ventilation, under specific room conditions. In the first part, velocity and temperature distributions of the impinging jet flow field predicted by different turbulence models are compared with detailed measurements. Results from the non-isothermal validation studies show that the accuracy of the simulation results is to a great extent dependent on the complexity of the turbulence models, due to complicated flow phenomena related to jet impingement, such as recirculation, curvature and instability. The f v  2 turbulence model shows the best performance with measurements, which is slightly better than the SST k-ω model but much better than the RNG k-ε model. The difference is assumed to be essentially related to the magnitude of turbulent kinetic energy predicted in the vicinity of the stagnation region. Results from the isothermal study show that both the SST k-ω and RNG k-ε models predict similar wall jet behaviours of the impinging jet flow. IVIn the second part, three sets of parametric studies were carried out by using validated CFD models. The first parametric study shows that the geometry of the air supply system has the most significant impact on the flow field. The rectangular air supply device, especially the one with larger aspect ratio, provides a longer penetration distance to the room, which is suitable for industrial ventilation. The second study reveals that the interaction effect of cooling ceiling, heat sources ...

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“…Pressure reflections from the impingement surface dampen velocity fluctuations normal to the wall, causing both slower growth of the radial wall jet compared to a free-air jet and sensitivity of the flow to streamline curvature [3]. These features prove to be somewhat difficult to represent with existing turbulence models [5]. Previous numerical studies of impinging jets have concentrated on turbulence or code performance.…”

Section: Background 21 Impinging Jetsmentioning

confidence: 99%

“…Recently slot jets have attracted more attention as they offer higher cooling effectiveness, greater uniformity and more controllability [7]. Again a jet maybe confined or unconfined [5,8]. Non-vertical configurations add complexity through non-uniform heating and buoyancy effects [8].…”

Section: Background 21 Impinging Jetsmentioning

confidence: 99%