Conjugated Heat Transfer on a Horizontal Surface Impinged by Circular Free-Surface Liquid Jet.

This study characterized the mean and fluctuating parts of the radial component of the local velocity in the stagnation region of an impinging, free-surface liquid jet striking a smooth flat plate. Four different nozzle exit conditions were studied, including fully developed pipe flow, a contoured nozzle, and turbulence-damped and -undamped sharp-edged orifices. Liquid jet Reynolds numbers in the range 30,000 to 55,000 were investigated. Velocities were measured using laser-Doppler velocimetry. Mean velocities were found to vary nearly linearly with radial location, with the slope of the line being a function of distance from the impingement plate. Dimensionless mean velocity gradients, of relevance to the heat transfer, were found to be a strong function of nozzle type, but roughly independent of jet Reynolds number for a given nozzle type. Turbulence levels were also found to be strongly influenced by the nozzle exit condition. Local heat transfer data corresponding to the flow structure measurements presented here are reported in Part 2 of this study.

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Heat transfer in the hydraulic jump region of circular free-surface liquid jets

International Journal of Heat and Mass Transfer ◽

10.1016/j.ijheatmasstransfer.2019.118823 ◽

2020 ◽

Vol 146 ◽

pp. 118823 ◽

Cited By ~ 1

Author(s):

Hossein Askarizadeh ◽

Hossein Ahmadikia ◽

Claas Ehrenpreis ◽

Reinhold Kneer ◽

Ahmadreza Pishevar ◽

...

Keyword(s):

Heat Transfer ◽

Free Surface ◽

Hydraulic Jump ◽

Liquid Jets ◽

Surface Liquid

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Impingement Heat Transfer of Free-Surface Liquid Jets

Heat Transfer, Volume 1 ◽

10.1115/imece2002-39396 ◽

2002 ◽

Cited By ~ 1

Author(s):

Albert Y. Tong

Keyword(s):

Heat Transfer ◽

Free Surface ◽

Stokes Equations ◽

Numerical Study ◽

Navier Stokes ◽

Liquid Jets ◽

Liquid Jet ◽

Stagnation Region ◽

Navier Stokes Equations ◽

Impingement Heat Transfer

The problem of convective heat transfer of a circular liquid jet impinging onto a substrate is studied numerically. The objective of the study is to understand the hydrodynamics and heat transfer of the impingement process. The Navier-Stokes equations are solved using a finite-volume formulation. The free surface of the jet is tracked by the volume-of-fluid method. The energy equation is modeled by using an enthalpy-based formulation. Detailed flow fields as well as free surface contours and pressure distributions on the substrate have been obtained. Local Nusselt number variations along the solid surface have also been calculated. The effects of several key parameters on the hydrodynamics and heat transfer of an impinging liquid jet have been examined. It has been found that the jet-inlet velocity profile and jet elevation have a significant effect on the hydrodynamics and heat transfer, particularly in the stagnation region, of an impinging jet. The numerical results have been compared with experimental data obtained from the literature. The close agreement supports the validity of the numerical study.

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Effect of Nozzle Configuration on Transport in the Stagnation Zone of Axisymmetric, Impinging Free-Surface Liquid Jets: Part 2—Local Heat Transfer

Journal of Heat Transfer ◽

10.1115/1.2911896 ◽

1992 ◽

Vol 114 (4) ◽

pp. 880-886 ◽

Cited By ~ 62

Author(s):

Y. Pan ◽

J. Stevens ◽

B. W. Webb

Keyword(s):

Heat Transfer ◽

Nusselt Number ◽

Free Surface ◽

Radial Velocity ◽

Velocity Gradient ◽

Local Heat Transfer ◽

Local Heat ◽

Liquid Jets ◽

Stagnation Zone ◽

Surface Liquid

This is the second of a two-part study on the flow structure and heat transfer characteristics of turbulent, free-surface liquid jets. Part 2 deals with the effect of selected nozzle configurations on the local heat transfer in the stagnation zone. Infrared techniques have been used to characterize the local heat transfer for the four nozzle configurations whose mean and turbulent flow structure was detailed in Part 1. The results show that for identical jet Reynolds numbers, significant differences exist in the magnitudes of the local Nusselt number for the nozzle types studied. Differences of approximately 40 percent were observed. Local heat transfer results reveal that for already turbulent jets, the mean radial velocity gradient appears to be more influential in determining the heat transfer than incremental changes in the level of turbulence (as measured by the radial component of the fluctuations). An empirical correlation of the experimental data supports this conclusion, and reveals that the stagnation Nusselt number is affected independently by the jet Reynolds number and the dimensionless mean radial velocity gradient.

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Free-surface liquid jet impingement on rib patterned superhydrophobic surfaces

Physics of Fluids ◽

10.1063/1.3593460 ◽

2011 ◽

Vol 23 (5) ◽

pp. 052104 ◽

Cited By ~ 22

Author(s):

D. Maynes ◽

M. Johnson ◽

B. W. Webb

Keyword(s):

Free Surface ◽

Jet Impingement ◽

Superhydrophobic Surfaces ◽

Liquid Jet ◽

Surface Liquid

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Numerical Simulation of a Radial Free Surface Liquid Jet Impinging on a Heated Surface

Journal of Fluid Flow Heat and Mass Transfer ◽

10.11159/jffhmt.2021.005 ◽

2021 ◽

Author(s):

Alok Khaware ◽

Likitha S. Siddanathi ◽

Patrick Sharkey ◽

Amine Ben Hadj Ali ◽

Vinay K. Gupta

Keyword(s):

Numerical Simulation ◽

Free Surface ◽

Heated Surface ◽

Liquid Jet ◽

Surface Liquid

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Pressure Drop in Generating Free-Surface Liquid Microjet Array From Short Cylindrical Orifices

Journal of Fluids Engineering ◽

10.1115/1.4004085 ◽

2011 ◽

Vol 133 (6) ◽

Cited By ~ 4

Author(s):

Avijit Bhunia ◽

C. L. Chen

Keyword(s):

Free Surface ◽

Pressure Drop ◽

Functional Dependence ◽

High Heat ◽

Current Data ◽

Nonlinear Dependence ◽

Liquid Jet ◽

High Heat Flux ◽

Research Attention ◽

Surface Liquid

Liquid microjet arrays have received a lot of research attention in recent years due to its high heat flux cooling capability. The microjets are generated from a jet head cavity with a liquid inlet port on one wall and an array of micro-orifices on another wall. An important, yet relatively less studied aspect of the topic is the pressure (also frequently referred to as the pressure drop) necessary to generate the jets and maintain certain jet velocity. In this study we investigate the pressure drop for17 different array patterns of liquid jet issuing in a surrounding gas (air) medium, i.e., a free surface liquid jet. The number of jets varies from 1 to 126, while the jet diameter ranges from 99 to 208 μm. The current results show more than 200% deviation from the existing correlations in the literature. Through a systematic experimental study we identify the functional dependence of pressure drop on the various geometric parameters. The results uncover the reasons behind the widespread disagreement between the current data and the existing correlations. Pressure drop shows a weak, nonlinear dependence on the orifice wall thickness, compared to the linear dependence used in the existing correlations. Furthermore, the depth of the jet head cavity is shown to be an important parameter dictating pressure drop, unlike the previous studies that inherently assume the cavity to be an infinite reservoir. A new dimensionless pressure drop parameter is proposed and its variation with the jet Reynolds number is correlated. The new correlation predicts all the experimental data within a ± 10% range.

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