Non-Circular Hydraulic Jump on a Moving Surface due to an Impinging Circular Free Surface Jet of Water

2012 ◽  
Vol 83 (7) ◽  
pp. 653-670
Author(s):  
Mohammad M. Seraj ◽  
Mohamed S. Gadala
Keyword(s):  
Free Surface ◽  
Hydraulic Jump ◽  
Moving Surface ◽  
Surface Jet

Toward Modular Prediction of Free-Surface Jet Array Cooling: The Hydraulic Jump Location and Non-Monotonous Heat Transfer

2016 ◽  
Author(s):  
Herman D. Haustein
Keyword(s):  
Heat Transfer ◽  
Free Surface ◽  
Hydraulic Jump ◽  
Liquid Extraction ◽  
Jet Interaction ◽  
Free Jet ◽  
Key Issues ◽  
Surface Jet ◽  
Prediction Approach ◽  
Jet Array

The present study develops the ground work for modular prediction of free-surface jet arrays. Jet arrays generate one of the highest single-phase heat transfer rates, while covering reasonably large areas with good thermal uniformity, relevant to electronics cooling. However, due to liquid evacuation problems, free-jet arrays suffer from flooding, cross-flow and jet interaction, together with the large amount of influencing geometrical parameters, this makes them very difficult to predict. For the modular prediction approach to be applied, key issues are here addressed: experiments were conducted employing de-ionized water in both single and basic multiple-jet array (2×2, with local liquid extraction in the jet interaction zones) configurations. Modular conditions, wherein all jets are similar to each other, were created experimentally in a consistent fashion, by use of liquid extraction in the jet-interaction zones. Based on present and previous experimental data the influencing parameters on the pre-jump depth were identified. This description was then used to predict the location of the hydraulic jump (as dependant on the measured post-jump depth). The model combines elements of two previous approaches the shallow-water vs. jump conservation model, and obtains good agreement with available data. In addition conditions were shown for maximizing the distance at which the hydraulic jump occurs — to the point that the supercritical flows of adjacent jets touch (standing fountain type jump). This not only permits prediction of the supercritical flow heat transfer distribution over almost the entire array area, but also reduces the low heat transfer post-jump regions to a minimum. Finally, a more universal single-jet heat transfer model was developed incorporating inherent self-similarities recently identified by the authors and considering all relevant parameters: jet velocity profiles, nozzle-plate spacing, and inclination relative to gravity, to predict stagnation heat transfer as well as its radial decay. It is further identified that the influence of inclination is also of vital importance to free-surface jets (breakage of symmetry) and must be examined in future studies. By addressing these three key issues the foundation for a modular prediction of heat transfer under a free jet array is laid.

Computation of Turbulent Flow in a Thin Liquid Layer of Fluid Involving a Hydraulic Jump

1991 ◽  
Vol 113 (3) ◽  
pp. 411-418 ◽  
Author(s):  
M. M. Rahman ◽  
A. Faghri ◽  
W. L. Hankey
Keyword(s):  
Free Surface ◽  
Hydraulic Jump ◽  
Grid Method ◽  
Optimization Procedure ◽  
Solid Boundary ◽  
Plane Flow ◽  
Recirculating Flow ◽  
Flow Configurations ◽  
Rapid Deceleration ◽  
Predictor Corrector

Numerically computed flow fields and free surface height distributions are presented for the flow of a thin layer of liquid adjacent to a solid horizontal surface that encounters a hydraulic jump. Two kinds of flow configurations are considered: two-dimensional plane flow and axisymmetric radial flow. The computations used a boundary-fitted moving grid method with a k-ε model for the closure of turbulence. The free surface height was determined by an optimization procedure which minimized the error in the pressure distribution on the free surface. It was also checked against an approximate procedure involving integration of the governing equations and use of the MacCormack predictor-corrector method. The computed film height also compared reasonably well with previous experiments. A region of recirculating flow as found to be present adjacent to the solid boundary near the location of the jump, which was caused by a rapid deceleration of the flow.

Jet Impingement of a Non-Newtonian Fluid

2006 ◽  
Author(s):  
Jiangang Zhao ◽  
Roger E. Khayat
Keyword(s):  
Boundary Layer ◽  
Free Surface ◽  
Hydraulic Jump ◽  
Similarity Solutions ◽  
Surface Velocity ◽  
Free Surface Velocity ◽  
Viscous Boundary Layer ◽  
Boundary Layer Region ◽  
Layer Region ◽  
Viscous Boundary

The similarity solutions are presented for the wall flow which is formed when a smooth planar jet of power-law fluids impinges vertically on to a horizontal plate, and spreads out in a thin layer bounded by a hydraulic jump. This problem is formulated analogous to radial jet flow problem and the solution procedure is accounted for by means of similarity solution of the boundary-layer equation [1] for Newtonian fluids. For the convenience of analysis, the flow may be divided into three regions, namely a developing boundary-layer region, a fully viscous boundary-layer region, and a hydraulic jump region. The similarity solutions of the film thickness and free surface velocity in fully viscous boundary-layer region include unknown constant L, which is solved numerically and approximately in the developing boundary-layer flow region. Comparison between the numerical and approximate solutions leads generally to good agreement, except for severely shear-thinning fluids. The boundary-layer solution depends on two parameters: power-law index n and α, the dimensionless flow parameters. The effect of α on film thickness and free surface velocity is investigated. The relations between the position of the hydraulic jump and dimensionless flow parameter are obtained and the effect of α on the position of the jump is presented.

scholarly journals Experimental Characterization of the Hydraulic Jump Profile and Velocity Distribution in a Stilling Basin Physical Model

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1758
Author(s):  
Juan Macián-Pérez ◽  
Francisco Vallés-Morán ◽  
Santiago Sánchez-Gómez ◽  
Marco De-Rossi-Estrada ◽  
Rafael García-Bartual
Keyword(s):  
Free Surface ◽  
Energy Dissipation ◽  
Velocity Distribution ◽  
Physical Model ◽  
Hydraulic Jump ◽  
Surface Profile ◽  
Air Entrainment ◽  
Stilling Basin ◽  
Free Surface Profile ◽  
Stilling Basins

The study of the hydraulic jump developed in stilling basins is complex to a high degree due to the intense velocity and pressure fluctuations and the significant air entrainment. It is this complexity, bound to the practical interest in stilling basins for energy dissipation purposes, which brings the importance of physical modeling into the spotlight. However, despite the importance of stilling basins in engineering, bibliographic studies have traditionally focused on the classical hydraulic jump. Therefore, the objective of this research was to study the characteristics of the hydraulic jump in a typified USBR II stilling basin, through a physical model. The free surface profile and the velocity distribution of the hydraulic jump developed within this structure were analyzed in the model. To this end, an experimental campaign was carried out, assessing the performance of both, innovative techniques such as the time-of-flight camera and traditional instrumentation like the Pitot tube. The results showed a satisfactory representation of the free surface profile and the velocity distribution, despite some discussed limitations. Furthermore, the instrumentation employed revealed the important influence of the energy dissipation devices on the flow properties. In particular, relevant differences were found for the hydraulic jump shape and the maximum velocity positions within the measured vertical profiles, when compared to classical hydraulic jumps.

scholarly journals Image processing for hydraulic jump free-surface detection: coupled gradient/machine learning model

2020 ◽  
Vol 31 (10) ◽  
pp. 104003
Author(s):  
Robert Ljubičić ◽  
Ivana Vićanović ◽  
Budo Zindović ◽  
Radomir Kapor ◽  
Ljubodrag Savić
Keyword(s):  
Machine Learning ◽  
Image Processing ◽  
Free Surface ◽  
Hydraulic Jump ◽  
Learning Model ◽  
Surface Detection ◽  
Machine Learning Model

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

2020 ◽  
Vol 146 ◽  
pp. 118823 ◽  
Author(s):  
Hossein Askarizadeh ◽  
Hossein Ahmadikia ◽  
Claas Ehrenpreis ◽  
Reinhold Kneer ◽  
Ahmadreza Pishevar ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Free Surface ◽  
Hydraulic Jump ◽  
Liquid Jets ◽  
Surface Liquid

Hydrodynamics of quenching with impinging free-surface jet

2012 ◽  
Vol 55 (13-14) ◽  
pp. 3677-3685 ◽  
Author(s):  
Nitin Karwa ◽  
Lukas Schmidt ◽  
Peter Stephan
Keyword(s):  
Free Surface ◽  
Surface Jet

Classical hydraulic jump: free surface profile

1993 ◽  
Vol 20 (3) ◽  
pp. 536-539 ◽  
Author(s):  
Willi H. Hager
Keyword(s):  
Free Surface ◽  
Channel Flow ◽  
Hydraulic Jump ◽  
Simple Formula ◽  
Open Channel ◽  
Surface Profile ◽  
Novel Approach ◽  
Flow Hydraulics ◽  
Channel Surface ◽  
Free Surface Profile

Based on a large number of experiments, a simple formula is developed for the time-averaged free surface profile of a classical hydraulic jump. This novel approach is based on the length of the roller. The resulting surface profile fits the data well for usual inflow Froude numbers in the range of 2 to 10. Key words: backwater, channel flow, hydraulics, open channel, surface profile.

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