Experimental investigation of an axisymmetric, impinging turbulent jet. 1. Velocity field

Fairweather, Michael; Hargrave, Graham K.

doi:10.1007/s00348-002-0479-7

Cited by 66 publications

(62 citation statements)

References 16 publications

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“…In this respect, several experimental and direct numerical simulations (DNS) studies have been carried out in the past (e.g., [5][6][7][8][9][10][11][12][13][14][15][16][17]) in order to provide a deeper understanding about the underlying physical effects in such flows. The majority of these studies were focused on a single jet impinging normally on a heated solid surface using well-defined, fully-developed turbulent inlet conditions.…”

Section: Introductionmentioning

confidence: 99%

“…Fairweather and Hargrave [10] applied particle image velocimetry (PIV) to analyze the recirculation zone within the flow that carries material from the periphery of the wall-jet back to its initial regions. Regarding turbulent flow dynamics at the stagnation region, Tummers et al [5] reported on detailed near-wall measurements of mean velocities and Reynolds stresses using two-component LDV and PIV.…”

Section: Introductionmentioning

confidence: 99%

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Database of Near-Wall Turbulent Flow Properties of a Jet Impinging on a Solid Surface under Different Inclination Angles

Ries

Rißmann

et al. 2018

Fluids

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Abstract:In the present paper, direct numerical simulation (DNS) and particle image velocimetry (PIV) have been applied complementarily in order to generate a database of near-wall turbulence properties of a highly turbulent jet impinging on a solid surface under different inclination angles. Thereby, the main focus is placed on an impingement angle of 45 • , since it represents a good generic benchmark test case for a wide range of technical fluid flow applications. This specific configuration features very complex flow properties including the presence of a stagnation point, development of the shear boundary layer and strong streamline curvature. In particular, this database includes near-wall turbulence statistics along with mean and rms velocities, budget terms in the turbulent kinetic energy equation, anisotropy invariant maps, turbulent length/time scales and near-wall shear stresses. These properties are useful for the validation of near-wall modeling approaches in the context of Reynolds-averaged Navier-Stokes (RANS) and large-eddy simulations (LES). From this study, in which further impingement angles (0 • , 90 • ) have been considered in the experiments only, it turns out that (1) the production of turbulent kinetic energy appears negative at the stagnation point for an impingement angle other than 0 • and is balanced predominantly by pressure-related diffusion, (2) quasi-coherent thin streaks with large characteristic time scales appear at the stagnation region, while the organization of the flow is predominantly toroidal further downstream, and (3) near-wall shear stresses are low at the stagnation region and intense in regions where the direction of the flow changes suddenly.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Database of Near-Wall Turbulent Flow Properties of a Jet Impinging on a Solid Surface under Different Inclination Angles

Ries

Rißmann

et al. 2018

Fluids

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“…To overcome limitations of the hot-wire measurement near the impingement region where high turbulence occurs, advanced measuring techniques are employed by e.g. Fairweather and Hargrave (2002) and Narayanan et al (2004) for investigations of impinging jet flow.…”

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].…”

Section: Background 21 Impinging Jetsmentioning

confidence: 99%

“…This is usually due to their high heat and mass transfer rates that leads to use in many heating, cooling and drying operations such as in the paper, electronics and textiles industries [2]. The mass transfer properties are exploited in applications such as mine ventilation, spray painting, rockets and vertical-take-off-and-landing vehicles [3]. As well as their many industrial and practical applications impinging jets lend themselves very well to being used as benchmark test cases for numerical validation as the relatively simple geometries have flow characteristics that can be extremely complex and challenging to model.…”

Section: Introductionmentioning

confidence: 99%

Exploration of a horizontal confined impinging heated jet using both experimental and numerical methods

Fahey¹,

Wakes²,

Shaw³

2007

The International Journal of Multiphysics

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Experimental investigation of an axisymmetric, impinging turbulent jet. 1. Velocity field

Cited by 66 publications

References 16 publications

Database of Near-Wall Turbulent Flow Properties of a Jet Impinging on a Solid Surface under Different Inclination Angles

Database of Near-Wall Turbulent Flow Properties of a Jet Impinging on a Solid Surface under Different Inclination Angles

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

Exploration of a horizontal confined impinging heated jet using both experimental and numerical methods

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