Effects of Fluid Viscosity and Impingement Angle on Submerged Jet Flowfields

2018 ◽  
Author(s):  
Soroor Karimi ◽  
Matthew Fulton ◽  
Siamack A. Shirazi ◽  
Brenton McLaury
Keyword(s):  
Maximum Velocity ◽  
Jet Impingement ◽  
Reynolds Numbers ◽  
Fluid Viscosity ◽  
Impingement Angle ◽  
Submerged Jet ◽  
Glass Spheres ◽  
Image Velocimetry ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Experiments

Many researchers have utilized submerged jet impingement geometry to study solid particle erosion/corrosion. However, only a few studies have investigated changing impingement angle and fluid viscosity. In this study, Particle Image Velocimetry (PIV) experiments were conducted using 14 micron glass spheres for direct impingement geometry at viscosities of 1, 14, and 55 cP. These viscosities correspond to Reynolds numbers of approximately 57000, 4000, and 1000, respectively. It was observed that by increasing the viscosity the flow exiting the nozzle transitioned from extremely turbulent to laminar flow. The data indicated fully turbulent flow at the outlet for viscosities of 1 and 14 cP. In the case of 55 cP flow, the flow exiting the nozzle became laminar contributing to a higher maximum velocity in 55 cP flow. Experiments at these viscosities were also conducted at impingement angles of 90, 75, and 45 degrees to investigate the effects of the impinging jet angle on a flat plate. Additionally, a series of Computational Fluid Dynamics (CFD) simulations of the flowfield were performed to compare with the experimental data collected in this paper.

Velocity distribution around a sphere descending in a linearly stratified fluid

2017 ◽  
Vol 826 ◽  
pp. 759-780 ◽  
Author(s):  
Shinya Okino ◽  
Shinsaku Akiyama ◽  
Hideshi Hanazaki
Keyword(s):  
Boundary Layer ◽  
Velocity Distribution ◽  
High Speed ◽  
Particle Image ◽  
Maximum Velocity ◽  
Reynolds Numbers ◽  
Stratified Fluid ◽  
Velocity Variation ◽  
Image Velocimetry ◽  
Wave Patterns

The flow around a sphere descending at constant speed in a salt-stratified fluid is observed by particle image velocimetry. A unique characteristic of this flow is the appearance of a thin and high-speed rear jet whose maximum velocity can reach more than five times the sphere velocity. In this study we have investigated how the velocity distributions, especially those in the jet and in the boundary layer of the sphere, vary when the Froude number $Fr(=W^{\ast }/N^{\ast }a^{\ast })$ or the Reynolds number $Re(=W^{\ast }(2a^{\ast })/\unicode[STIX]{x1D708}^{\ast })$ ($W^{\ast }$: vertical velocity of the sphere, $N^{\ast }$: Brunt–Väisälä frequency, $a^{\ast }$: radius of the sphere, $\unicode[STIX]{x1D708}^{\ast }$: kinematic viscosity of the fluid) is changed. The results show that the radius of the jet and the thickness of the boundary layer are comparable, and they decrease for smaller Froude numbers and larger Reynolds numbers. Both of them are estimated at moderate Reynolds numbers by the primitive length scale of the stratified fluid ($l_{\unicode[STIX]{x1D708}}^{\ast }=\sqrt{\unicode[STIX]{x1D708}^{\ast }/N^{\ast }}$), or in non-dimensional form by $l_{\unicode[STIX]{x1D708}}^{\ast }/2a^{\ast }=(Fr/2Re)^{1/2}$. The overall velocity distribution in the lee of the sphere is measured to identify the internal wave patterns and their effect on the velocity variation along the jet. Corresponding numerical simulation results using the axisymmetry assumption are in agreement with the experimental results.

Thermal and Flow Visualization of Submerged Jet Impingement Boiling With FC-72

2012 ◽  
Author(s):  
Preeti Mani ◽  
Vinod Narayanan
Keyword(s):  
High Speed ◽  
Bubble Dynamics ◽  
Jet Impingement ◽  
Reynolds Numbers ◽  
Radial Temperature ◽  
Submerged Jet ◽  
Dielectric Fluids ◽  
Wall Superheat ◽  
Chemical Inertness ◽  
Jet Impingement Boiling

Dielectric fluids like FC-72 have been popularly used as electronic coolants owing to their chemical inertness and low saturation temperatures at atmospheric pressure. This work visualizes the heat transfer characteristics of FC-72 during submerged jet impingement boiling on a silicon surface heated by means of a thin film serpentine heater. Infrared thermography is used to obtain quantitative thermal maps of the boiling process from beneath the surface. Simultaneous high-speed visualization is used to record the corresponding bubble dynamics on the top surface. Experiments for two jet Reynolds numbers are compared with pool boiling under saturated conditions at a fixed surface to nozzle diameter ratio. Area-averaged temperatures evaluated from the thermal maps are used to describe the boiling trends for increasing and decreasing heat flux. Wall superheat required for phase-change varies randomly with increasing jet Reynolds numbers. Incipience overshoot as high as ∼21°C is observed and visually documented for the lower jet flow rate. Radial temperature profiles along the surface indicate that locally overshoots may vary significantly (∼8–21°C) for conditions with extremely high incipient superheats.

Microstructured Surfaces for Single-Phase Jet Impingement Heat Transfer Enhancement

2013 ◽  
Vol 5 (3) ◽  
Author(s):  
Gilberto Moreno ◽  
Sreekant Narumanchi ◽  
Travis Venson ◽  
Kevin Bennion
Keyword(s):  
Heat Transfer ◽  
Single Phase ◽  
Jet Impingement ◽  
Reynolds Numbers ◽  
Surface Roughening ◽  
Submerged Jet ◽  
Nusselt Numbers ◽  
Impingement Heat Transfer ◽  
Microstructured Surfaces ◽  
Microporous Coating

An experimental investigation was conducted to examine the use of microstructured surfaces to enhance jet impingement heat transfer. Three microstructured surfaces were evaluated: a microfinned surface, a microporous coating, and a spray pyrolysis coating. The performance of these surface coatings/structures was compared to the performance of simple surface roughening techniques and millimeter-scale finned surfaces. Experiments were conducted using water in both the free- and submerged-jet configurations at Reynolds numbers ranging from 3300 to 18,700. At higher Reynolds numbers, the microstructured surfaces were found to increase Nusselt numbers by 130% and 100% in the free- and submerged-jet configurations, respectively. Potential enhancement mechanisms due to the microstructured surfaces are discussed for each configuration. Finally, an analysis was conducted to assess the impacts of cooling a power electronic module via a jet impingement scheme utilizing microfinned surfaces.

scholarly journals Computational Analysis of Water-Submerged Jet Erosion

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3074
Author(s):  
Rached Ben-Mansour ◽  
Hassan M. Badr ◽  
Abdulrazaq A. Araoye ◽  
Ihsan Ul Haq Toor
Keyword(s):  
Aspect Ratio ◽  
Oil And Gas ◽  
Jet Impingement ◽  
Separation Distance ◽  
Water Medium ◽  
Financial Loss ◽  
Impingement Angle ◽  
Ansys Fluent ◽  
Submerged Jet ◽  
Thickness Loss

Erosion causes substantial damage in many industrial equipment such as pump components, valves, elbows, and plugged tees. In most cases, erosion is coupled with corrosion, resulting in major financial loss (nearly 3.4% of the global gross domestic product) as evidenced in oil and gas industries. In most cases, the erosion occurs in a submerged water medium. In this paper, erosion characteristics of stainless steel 316 were investigated computationally in a water-submerged jet impingement setup. The erosion profiles and patterns were obtained for various parameters over ranges of inlet velocities (3 to 16 m/s), nozzle diameters (5 to 10 mm), nozzle–target distances (5 to 20 mm), nozzle shapes (circular, elliptical, square, and rectangular), impingement angles (60° to 90°), and particle sizes (50 to 300 µm). The range of Reynolds number studied based on nozzle diameters is 21,000–120,000. The Eulerian–Lagrangian approach was used for flow field prediction and particle tracking considering one-way coupling for the particle–fluid interaction. The Finnie erosion model was implemented in ANSYS-Fluent 19.2 and used for erosion prediction. The computational model was validated against experimental data and the distributions of the erosion depth as well as the locations of the of maximum and minimum erosion points are well matched. As expected, the results indicate an increase in loss of material thickness with increasing jet velocity. Increasing the nozzle diameter caused a reduction in the maximum depth of eroded material due to decreasing the particle impact density. At a fixed fluid inlet velocity, the maximum thickness loss increases as the separation distance between the nozzle outlet and target increases, aspect ratio of nozzle shape decreases, and impingement angle increases. The erosion patterns showed that the region of substantial thickness loss increases as nozzle size/stand-off height increases and as particle size decreases. In addition, increasing the aspect ratio and impingement angle creates skewed erosion patterns.

Submerged Jet Impingement Boiling of Saturated Water Under Sub-Atmospheric Conditions

2010 ◽  
Author(s):  
Ruander Cardenas ◽  
Preeti Mani ◽  
Vinod Narayanan
Keyword(s):  
Heat Transfer ◽  
Single Phase ◽  
Jet Impingement ◽  
Reynolds Numbers ◽  
Internal Diameter ◽  
Atmospheric Conditions ◽  
Submerged Jet ◽  
Surface Distance ◽  
Saturated Water ◽  
Jet Impingement Boiling

An experimental study of mini-jet impingement boiling is presented for saturated conditions. Unique to this study is documentation of boiling characteristics of a submerged water jet under sub-atmospheric conditions. Data are reported at a fixed nozzle-to-surface distance that corresponds to a monotonic decrease in heat transfer coefficient for single-phase jet impingement. A mini nozzle is used in the present study with an internal diameter of 1.16 mm. Experiments are performed at three sub-atmospheric pool pressures of 0.2 bar, 0.3 bar and 0.5 bar. At each pressure, jet impingement boiling at four Reynolds numbers are characterized and compared with the pool boiling heat transfer. Enhancements in critical heat flux with increasing Re are observed for all pressures.

scholarly journals Validation of a CFD Methodology for Positive Displacement LVAD Analysis Using PIV Data

2009 ◽  
Vol 131 (11) ◽  
Author(s):  
Richard B. Medvitz ◽  
Varun Reddy ◽  
Steve Deutsch ◽  
Keefe B. Manning ◽  
Eric G. Paterson
Keyword(s):  
Left Ventricular ◽  
Hydrodynamic Performance ◽  
Ventricular Assist ◽  
Shear Rates ◽  
Eddy Simulation ◽  
Positive Displacement ◽  
Image Velocimetry ◽  
Computational Fluid Dynamics Cfd ◽  
High Level

Computational fluid dynamics (CFD) is used to asses the hydrodynamic performance of a positive displacement left ventricular assist device. The computational model uses implicit large eddy simulation direct resolution of the chamber compression and modeled valve closure to reproduce the in vitro results. The computations are validated through comparisons with experimental particle image velocimetry (PIV) data. Qualitative comparisons of flow patterns, velocity fields, and wall-shear rates demonstrate a high level of agreement between the computations and experiments. Quantitatively, the PIV and CFD show similar probed velocity histories, closely matching jet velocities and comparable wall-strain rates. Overall, it has been shown that CFD can provide detailed flow field and wall-strain rate data, which is important in evaluating blood pump performance.

scholarly journals Fish larvae exploit edge vortices along their dorsal and ventral fin folds to propel themselves

2016 ◽  
Vol 13 (116) ◽  
pp. 20160068 ◽  
Author(s):  
Gen Li ◽  
Ulrike K. Müller ◽  
Johan L. van Leeuwen ◽  
Hao Liu
Keyword(s):  
Larval Fish ◽  
Fish Larvae ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Bony Fish ◽  
The Body ◽  
Functional Explanation ◽  
Image Velocimetry ◽  
Median Fins

Larvae of bony fish swim in the intermediate Reynolds number ( Re ) regime, using body- and caudal-fin undulation to propel themselves. They share a median fin fold that transforms into separate median fins as they grow into juveniles. The fin fold was suggested to be an adaption for locomotion in the intermediate Reynolds regime, but its fluid-dynamic role is still enigmatic. Using three-dimensional fluid-dynamic computations, we quantified the swimming trajectory from body-shape changes during cyclic swimming of larval fish. We predicted unsteady vortices around the upper and lower edges of the fin fold, and identified similar vortices around real larvae with particle image velocimetry. We show that thrust contributions on the body peak adjacent to the upper and lower edges of the fin fold where large left–right pressure differences occur in concert with the periodical generation and shedding of edge vortices. The fin fold enhances effective flow separation and drag-based thrust. Along the body, net thrust is generated in multiple zones posterior to the centre of mass. Counterfactual simulations exploring the effect of having a fin fold across a range of Reynolds numbers show that the fin fold helps larvae achieve high swimming speeds, yet requires high power. We conclude that propulsion in larval fish partly relies on unsteady high-intensity vortices along the upper and lower edges of the fin fold, providing a functional explanation for the omnipresence of the fin fold in bony-fish larvae.

The Dynamics of a Cantilevered Pipe Aspirating Fluid Studied by Experimental, Numerical and Analytical Methods

2010 ◽  
Author(s):  
Dana Giacobbi ◽  
Stephanie Rinaldi ◽  
Christian Semler ◽  
Michael P. Pai¨doussis
Keyword(s):  
Analytical Model ◽  
Low Flow ◽  
Computational Fluid Dynamics Cfd ◽  
Computational Structural Mechanics ◽  
Cantilevered Pipe ◽  
The Galerkin Method ◽  
Csm Model ◽  
Ocean Mining ◽  
Flow Experiments ◽  
Flow Velocities

This paper investigates the dynamics of a slender, flexible, aspirating cantilevered pipe, ingesting fluid at its free end and conveying it towards its clamped end. The problem is interesting not only from a fundamental perspective, but also because applications exist, notably in ocean mining [1]. First, the need for the present work is demonstrated through a review of previous research into the topic — spanning many years and yielding often contradictory results — most recently concluding that the system loses stability by flutter at relatively low flow velocities [2]. In the current paper, that conclusion is refined and expanded upon by exploring the problem in three ways: experimentally, numerically and analytically. First, air-flow experiments, in which the flow velocity of the fluid was varied and the frequency and amplitude of oscillation of the pipe were measured, were conducted using different elastomer pipes and intake shapes. Second, a fully-coupled Computational Fluid Dynamics (CFD) and Computational Structural Mechanics (CSM) model was developed in ANSYS in order to simulate experiments and corroborate experimental results. Finally, using an analytical approach, the existing linear equation of motion describing the system was significantly improved upon, and then solved via the Galerkin method in order to determine its stability characteristics. Heavily influenced by a CFD analysis, the proposed analytical model is different from previous ones, most notably because of the inclusion of a two-part fluid depressurization at the intake. In general, both the actual and numerical experiments suggest a first-mode loss of stability by flutter at relatively low flow velocities, which agrees with the results from the new analytical model.

Splattering During Turbulent Liquid Jet Impingement on Solid Targets

1994 ◽  
Vol 116 (2) ◽  
pp. 338-344 ◽  
Author(s):  
Sourav K. Bhunia ◽  
John H. Lienhard
Keyword(s):  
Jet Impingement ◽  
Reynolds Numbers ◽  
Turbulent Pipe Flow ◽  
Liquid Jet ◽  
Straight Tube ◽  
Aerosol Formation ◽  
Transfer Processes ◽  
Onset Condition ◽  
Impingement Heat Transfer ◽  
Complete Study

In turbulent liquid jet impingement, a spray of droplets often breaks off of the liquid layer formed on the target. This splattering of liquid alters the efficiencies of jet impingement heat transfer processes and chemical containment safety devices, and leads to problems of aerosol formation in jet impingement cleaning processes. In this paper, we present a more complete study of splattering and improved correlations that extend and supersede our previous reports on this topic. We report experimental results on the amount of splattering for jets of water, isopropanol-water solutions, and soap-water mixtures. Jets were produced by straight tube nozzles of diameter 0.8–5.8 mm, with fully developed turbulent pipe-flow upstream of the nozzle exit. These experiments cover Weber numbers between 130-31,000, Reynolds numbers between 2700-98,000, and nozzle-to-target separations of 0.2 ≤ l/d ≤ 125. Splattering of up to 75 percent of the incoming jet liquid is observed. The results show that only the Weber number and l/d affect the fraction of jet liquid splattered. The presence of surfactants does not alter the splattering. A new correlation for the onset condition for splattering is given. In addition, we establish the range of applicability of the model of Lienhard et al. (1992) and we provide a more accurate set of coefficients for their correlation.

Dynamics of Liquid Sheet Breakup in Splash Plate Atomization

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
G. Thunivumani ◽  
Hrishikesh Gadgil
Keyword(s):  
Solid Surface ◽  
Weber Number ◽  
Jet Impingement ◽  
Liquid Sheet ◽  
Force Balance ◽  
Impingement Angle ◽  
Wide Range ◽  
Perforated Sheet ◽  
Sheet Breakup ◽  
Regime Map

An experimental study was conducted to investigate the breakup of a liquid sheet produced by oblique impingement of a liquid jet on a plane solid surface. Experiments are carried out over a wide range of jet Weber number (80–6300) and various jet impingement angles (30 deg, 45 deg, and 60 deg) are employed to study the sheet dynamics. The breakup of a liquid sheet takes place in three modes, closed rim, open rim, and perforated sheet, depending upon the Weber number. The transitions across the modes are also influenced by the impingement angle with the transition Weber number reducing with increase in impingement angle. A modified regime map is proposed to illustrate the role of impingement angle in breakup transitions. A theoretical model based on force balance at the sheet edge is developed to predict the sheet parameters by taking the shear interaction between the sheet and the solid surface into account. The sheet shape predicted by the model fairly matches with the experimentally measured sheet shape. The breakup length and width of the sheet are measured and comparisons with the model predictions show good agreement in closed rim mode of breakup.

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