Computational investigation of vertical slurry jets in water (original) (raw)
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Experimental Study of Sand and Slurry Jets in Water
This paper presents the results of an experimental study of turbulent sand jets and sand-water slurry jets impinging vertically into a stagnant water body. The jets contained silica sand with a median diameter D 50 of 206 m, and with an initial concentration 0.60 by volume for the sand jets, and 0.055-0.124 by volume for the slurry jets. The jets had densimetric Froude numbers between 2.0 and 5.94. The sand concentration and velocity profiles were measured simultaneously using a novel fiber optical probe, up to a distance of 130d o for sand jets, and 65d o for slurry jets, where d o is the jet diameter at the water surface. The jets were found to have self-similar Gaussian profiles. The centerline sand concentration within the jets was found to decrease rapidly, following trends similar to single phase plumes. The centerline sand velocity profile decreased significantly before reaching a plateau region. The "terminal" centerline sand velocity within this region varies somewhat depending upon sand mass flux, and is between 0.32 and 0.43 m/s. The spreading rates of the jets were found to vary with the particle Froude number. Within the sand jets and the higher Froude number slurry jet, the sand concentration had a smaller spreading rate than the velocity. The other slurry jets had equal concentration/velocity spreading rates. The momentum flux of the sand within the jets was found to decrease sharply, followed by a constant flux below a depth of 25 to 30 jet diameters.
An experimental study of circular sand–water wall jets
International Journal of Multiphase Flow, 2015
Laboratory experiments were carried out to study the effects of sand particles on circular sand-water wall jets. Mean and turbulence characteristics of sand particles in the sand-water wall jets were measured for different sand concentrations c o ranging from 0.5% to 2.5%. Effects of sand particle size on the centerline sand velocity of the jets were evaluated for sand size ranging from 0.21 mm to 0.54 mm. Interesting results with the range of measurements are presented in this paper. It was found that the centerline sand velocity of the wall jets with larger particle size were 15% higher than the jets with smaller particle size. Concentration profiles in the vertical direction showed a peak value at x/ d = 5 (where x is the longitudinal distance from the nozzle and d is the nozzle diameter) and the sand concentration decreased linearly for x/d > 5. Experimental results showed that the turbulence level enhanced from the nozzle to x/d = 10. For sand-water wall jets with a higher concentration (c o = 1.5-2.5%), the turbulence intensity became smaller than the corresponding single-phase wall jets by 34% due to turbulent modulation. A modified logarithmic formulation was introduced to model the longitudinal turbulent intensity at the centerline and along the axis of the jet.
An Experimental Study of Sand Jet in Stagnant Water
The study of sand-laden turbulent jet is one of the interest areas for researchers in the field of hydraulics as it has many important engineering applications such as marine bed capping, mining operations, hydro-transport, dredging material disposal, and discharge of domestic and industrial wastewater. Several in-depth studies have been conducted previously focusing on various parameters. In this paper, results from a simple experimental study have been presented. Sand jet of same sized particle diameter has been used during the whole experiment. Three types of nozzle diameters and for each diameter of nozzle different sets of sand masses have been used for the study. The optical probe has been used in six different positions to register the voltage data and thus to facilitate sand particle frontal velocity calculation. The last position of the probe has been set depth enough to ensure that the sand particle has attained its terminal velocity in most cases. Several experiments have been conducted to see the effect of nozzle diameter and sand mass on sand particle frontal velocity.
Experimental study of sand jet front in water
International Journal of Multiphase Flow, 2012
An experimental study was conducted to examine the behaviour of a sand jet front in water and its associated fluid motions with different sand particle sizes and initial sand jet diameters. The shape of sand jet front was found to be directly related to the particle Reynolds number of sand particles. The frontal velocity along the centreline of the jet axis was measured and compared to that of single-phase buoyant jets and particle thermals. The jet front settling velocity of small particles was found to be as large as 5 times that of the individual particle settling velocity. The presence of particles and the additional momentum generated by particles were found to reduce the growth rate of the jet front width, compared with those of the single-phase buoyant jets and particle thermals. Evolution of vortices and their structure were extracted from velocity fields by employing Galilean velocity decomposition and a local vortex identification technique. It was shown that, radial convection velocity can change the shape of the vortices. Large radial convection velocity transformed the vortex from semi-circular shape to elongated ellipsoid vortex. Effect of particles on turbulence of the carrier phase was studied. It was found that smaller particles increase turbulence attenuation of the carrier phase. Effect of particles on the modulation of turbulence can be described by the Stokes number along the jet axis. A classification was made for solid-liquid and solid-gas turbulent jets and new formulations were proposed to show the correlation between Stokes number and the turbulence attenuation of particle-laden turbulent jets.
Computational fluid dynamics modelling and experimental study of erosion in slurry jet flows
International Journal of Computational Fluid Dynamics, 2009
The application of computational fluid dynamics (CFDs) in the area of porous media and adsorption cooling system is becoming more practical due to the significant improvement in computer power. The results from previous studies have shown that CFD can be useful tool for predicting the water vapour flow pattern, temperature, heat transfer and flow velocity and adsorption rate. This paper investigates the effect of silica gel granular size on the water adsorption rate using computational fluid dynamics and gravimetric experimental (TGA) method.
Effect of sand particles on flow structure of free jet from a nozzle
Journal of Mechanical Engineering and Sciences
The Characteristics of single and two- phase flow from a circular turbulent free jet from a nozzle of 10 mm diameter were investigated experimentally and numerically. The measurements were conducted for ReJ = 10007 - 31561. The velocity was measured at location from the nozzle y/D (0-8) in axial and radial directions. The two phase measurement were done by using natural construction sand as a solid phase of sizes (220,350,550) µm and loading ratios (mass flow ratio of sand to mass flow rate of air) in the range (0.18-1.38). Two phase air velocity of jet showed that the introducing of natural sand particles gives lower jet velocity attributed to momentum transfer to particles. The smaller particle size leads to lower values of velocity. The velocity found to be decreased with loading ratio increase. The numerical simulation was performed for single and two phase jet flow. RNG K-ε turbulence model was used to simulate the flow of fluid and the discrete phase model to simulate the part...
This present study represents a numerical analysis of sand water slurry flow considering different sand particle sizes through horizontal pipeline of 5.5m length and 103 mm diameter at high velocity. Computational fluid dynamics was used for the numerical simulation; Eulerial two phase model was selected for modeling the multiphase flow and RNG K-epsilon model was adopted for modeling the turbulent flow. 90µm, 150µm and 270µm sand particle (Sp. Gravity 2.65) sizes were considered for this present study for a mixture flow velocity of 5.4m/s at various solid volumetric concentration levels (20%, 30% and 40%). The behaviour of various flow parameters viz. concentration distributions, velocity distributions and pressure drop were analyzed from the numerically simulated results. The influence of particle size and solid volumetric concentrations on various flow parameters were analyzed in this study. Finally the simulated results of pressure drop were validated with the experimental data available in previous literature. I. INTRODUCTION Demands for conveyance of solid materials through pipelines over a long distance have increased dramatically over the last few decades. This is because this mode of transportation of solid materials is more economical, more environment friendly, causes less air pollution and less road traffics than the conventional mode of solid material transportations. Many industries like power generation industries, pharmaceutical, construction industries, city municipality, oil and gas industries food processing industries etc handle the solid material transportation through pipelines. Generally solid materials are mixed with fluid and slurry is formed, then the slurry is made to flow through the pipeline for transportation. The flow patterns of these slurry (Solid-fluid mixture) shows a remarkable difference with the flow patterns of pure fluid flow through the pipeline and hence to obtain a detailed information about the slurry flow process behaviour of different flow parameters need to be observed carefully. Slurry flow is a multiphase complex flow problem. Computational fluid dynamics (CFD) is a numerical analysis platform where a wide range of multiphase flow problems can be analyzed with greater ease and low cost which would have been almost impossible with experimental work. CFD allows the researchers to adopt different complex multiphase models for proper modeling of the slurry flow.
Numerical investigations of liquid–solid slurry flows in a fully developed turbulent flow region
In this paper, a simplified 3D algebraic slip mixture (ASM) model is introduced to obtain the numerical solution in sand-water slurry flow. In order for the study to obtain the precise numerical solution in fully developed turbulent flow, the RNG K-e turbulent model was used with the ASM model. An unstructured (block-structured) non-uniform grid was chosen to discretize the entire computational domain, and a control volume finite difference method was used to solve the governing equations. The mean pressure gradients from the numerical solutions were compared with the authorsÕ experimental data and that in the open literature. The solutions were found to be in good agreement when the slurry mean velocity is higher than the corresponding critical deposition velocity. Moreover, the numerical investigations have displayed some important slurry flow characteristics, such as volume fraction distributions, slurry density, slip velocity magnitude, slurry mean velocity distributions, and slurry mean skin friction coefficient distributions in a fully developed section, that have never been displayed in the experiments.
Physics of Fluids
This paper investigates the evolution of oblique sand jets passing through a thin layer of oil and entering stagnant water known as oily sand jets. The jet evolution parameters include the frontal position, the trajectory of particle clusters, the frontal width, the area of oily sand clusters, cloud velocities, and bursting times. Two scaling parameters, known as aspect ratio and particle to nozzle size ratio, were found to control the evolution of oily sand jets. The results show that the ratio of a nozzle to sand particle size can cause particle channelization, which can significantly alter the motion of particle clusters in stagnant water. Moreover, the aspect ratio indicating the correlation between sand mass and nozzle diameter describes the dispersion of particle clusters during the evolution of oily sand jets. The frontal width of the oily sand jet was measured during the experiment, and the results were compared with the width of vertical sand jets in water. The results show...
Numerical Simulation of Sediment-Laden Jets in Static Uniform Environment Using Eulerian Model
Numerical Simulation of Sediment-Laden Jets in Static Uniform Environment Using Eulerian Model, 2012
"Sediment-laden jets were simulated with an Eulerian two-phase model that implements Euler–Euler coupled governing equations for fluid and solid phases. Both flow–particle and particle–particle interactions were considered in this model. A modified k–ε turbulence model was chosen to close the fluid phase equations. The computational results compared well with previous laboratory measurements. The characteristics of the flow fields of the two phases and the influences of hydraulic and geometric parameters on the distribution of the sediment-laden jet were analyzed on the basis of computational results. The calculation results reveal that if the initial velocity of the sediment-laden jet is high, the jet is sprayed higher and spreads further in the radial direction. The turbulent kinetic energy k and turbulent dissipation rate ε, whose decay rates are higher than that of the jet velocity, decrease rapidly after the sediment-laden jet enters the nozzle. For different values of the exit densimetric Froude number F, the profiles of deposited sediment and the axial distributions of the jet velocity, density deficit and turbulent kinetic energy are self-similar on a certain jet axis. The decay rate of the sand velocity is higher than that of water velocity along the axis of the sediment-laden jet, and if the sediment particle has a higher settling velocity, it has higher inertia and spreads less radially. Keywords: sediment-laden jet, numerical simulation, Eulerian model, self-similar, densimetric Froude number"