Sand-water Slurry Research Articles

Correction: Numerical simulation of sand–water slurry flow through pipe bend using CFD

Correction: Numerical simulation of sand–water slurry flow through pipe bend using CFD

Numerical simulation of sand–water slurry flow through pipe bend using CFD

Numerical simulation of sand–water slurry flow through pipe bend using CFD

An overview of the effect of stirrer design on the mechanical properties of Aluminium Alloy Matrix Composites fabricated by stir casting

An overview of the effect of stirrer design on the mechanical properties of Aluminium Alloy Matrix Composites fabricated by stir casting

Effect of specularity coefficient on hydrodynamic behaviors of slurry flows in horizontal pipes

The Eulerian–Eulerian two-fluid model (TFM) in combination with the kinetic theory of granular flow (KTGF) and the Johnson and Jackson boundary condition is widely used to simulate multiphase flows in engineering. However, this model requires the calibration of several parameters. One of these parameters is the specularity coefficient, which characterizes the particle–wall collisions. Thus far, research on this parameter has been lacking in the field of slurry flow simulations. In this study, the integration of TFM with KTGF and the Johnson and Jackson boundary condition is used to simulate the transportation of sand–water slurry in horizontal pipes. The effects of different specularity coefficient values on the predicted solids wall shear stress, velocity, and concentration are analyzed. It is found that the solids wall shear stress increases with the specularity coefficient and is more sensitive to the smaller specularity coefficient. As the specularity coefficient increases, the profiles of the solids velocity and concentration are rotated clockwise, shifting the maximum velocity point to a higher vertical location and producing a plumper solids concentration profile. These qualitative conclusions may be used as a reference for the specularity coefficient tuning process in the field of slurry transport simulations.

Experimental and Numerical analysis of Flow characteristics of sand water slurry in a horizontal pipe

The transportation of the solid material using hydraulic transportation method is economically the best method. The head loss occurs during transportation of slurry through horizontal pipelines usually depends on the rheological behavior of slurry, slurry concentration, particle size, and influx velocity. An experimental investigation has been performed using sand-water slurry flowing through the horizontal pipe section of a pilot plant test loop. The head loss obtained from the experimental results was validated through CFD simulation using FLUENT. The solid concentration of sand-water slurry and influx velocity used during both experiments and numerical simulation were in the range of 10-40% (by weight) and 1 to 4 m/s respectively. The numerical simulations were performed using five different turbulence models and the results obtained using SST k-omega model was in close agreement with experimental results. It is observed from both the experiment and numerical analysis that the pressure loss, granular pressure, volume fraction and skin fraction coefficient during transportation of slurry through a horizontal pipe is a function of solid concentration and influx velocity. The present study observed that as the flow velocity increases four times, the pressure loss is increasing more than 10 times. Uniform volume fraction at middle zone of outlet of the pipe is observed as both the slurry concentration and velocity of flow increases.

Computational fluid dynamics modeling of slurry flow in horizontal pipes: Effect of specularity coefficient on hydraulic gradient

The specularity coefficient is an important input parameter in the Johnson and Jackson boundary conditions. Thus far, research on this parameter has been lacking in the field of slurry flow simulations. In this study, the integration of the Eulerian–Eulerian two-fluid model with kinetic theory of granular flow and Johnson and Jackson boundary conditions is used to simulate the transportation of sand–water slurry in horizontal pipelines. A range of flow conditions, including high and low velocities, high and low concentrations, coarse and fine particles, and large and small pipes, is considered to study the effect of the specularity coefficient on the predicted hydraulic gradient. Then, the simulation results are compared with previous experimental measurements to determine the appropriate values of the specularity coefficient. The hydraulic gradient is found to be positively correlated with the specularity coefficient; in addition, it is more sensitive to the specularity coefficient when the specularity coefficient is less than 0.1. The appropriate value of the specularity coefficient decreases with the flow velocity and increases with the solid volume fraction. In the range of flow conditions considered, the findings may be used as a reference for future simulations in the research field of slurry transport.

Early Detection of the Wear of Coriolis Flowmeters Through In Situ Stiffness Diagnosis

Coriolis flowmeters have been widely employed in a variety of industrial applications. There is a potential that the measuring tube of a Coriolis flowmeter may be eroded when it is used to measure abrasive fluid such as slurry flow. However, it is challenging to verify the structural health of the flowmeter without process interruptions or using on-site calibration devices such as meter provers. This article presents an in situ structural health-monitoring technique through stiffness diagnosis to identify the potential wear occurring on the measuring tube. To measure the frequency response of a Coriolis flowmeter, which strongly depends on the structural characteristics of the tube, the tube is not only excited at a resonant frequency but also at two additional off-resonant frequencies. Through digital processing of the drive and sensor signals, the frequency response is obtained and a stiffness-related diagnostic parameter (SRDP) is extracted from a Coriolis flowmeter. The proposed stiffness diagnosis technique was experimentally evaluated on a commercial bent-tube Coriolis flowmeter with dilute sand-water slurry flow. The results illustrate that the slight tube erosion is successfully identified when a relative change in SRDP reaches -1%, showing a good capability for an early detection of tube wear. In addition, the outcomes from recalibration with water suggest that, after the erosion occurs, the flowmeter overestimates the mass flowrate and underestimates the flow density.

NUMERICAL INVESTIGATIONS ON FLOW CHARACTERISTICS OF SAND-WATER SLURRY THROUGH HORIZONTAL PIPELINE USING COMPUTATIONAL FLUID DYNAMICS

The study presents the numerical computational fluid dynamics (CFD) analysis of sand-water slurry flow with different sand particle sizes viz. 90µm, 125µm, 150µm, 200µm and 270µm having specific gravity of 2.65 through a 103 mm diameter, 5.5 m long horizontal pipeline for a high flow velocity of 5.4 m/s at various solid volumetric concentrations viz. 10%, 20%, 30%, 36% and 40%. Granular version of Eulerian two-phase model with dispersed particles along with RNG –epsilon approach has been utilized. Non-uniform structured mesh with a refinement near the wall boundary has been selected for discretizing the computational flow domain while Navier-Stokes governing equations are solved in FLUENT 14.0. The effects of the size of sand particles and solid volumetric concentrations on territorial concentration distributions, particle flow velocity and pressure drops have been studied and analyzed. Generalized mathematical correlation has been developed from the simulated results for calculating the consequences of the size of solid particles and solid volumetric concentration on pressure drop analytically. The simulated outcomes of pressure drop are validated with the experimental results. These outcomes will be very helpful in the setup of an experimental model for sand/water slurry flow pipelines in many industries viz. mining, construction, power generation etc.

Concentration distribution and deposition limit of medium-coarse sand-water slurry in inclined pipe

Abstract Sand-water slurry was investigated on an experimental pipe loop of inner diameter D = 100 mm with the horizontal, inclined, and vertical smooth pipe sections. A narrow particle size distribution silica sand of mean diameter 0.87 mm was used. The experimental investigation focused on the effects of pipe inclination, overall slurry concentration, and mean velocity on concentration distribution and deposition limit velocity. The measured concentration profiles showed different degrees of stratification for the positive and negative pipe inclinations. The degree of stratification depended on the pipe inclination and on overall slurry concentration and velocity. The ascending flow was less stratified than the corresponding descending flow, the difference increasing from horizontal flow up to an inclination angle of about +30°. The deposition limit velocity was sensitive to the pipe inclination, reaching higher values in the ascending than in the horizontal pipe. The maximum deposition limit value was reached for an inclination angle of about +25°, and the limit remained practically constant in value, about 1.25 times higher than that in the horizontal pipe. Conversely, in the descending pipe, the deposition limit decreased significantly with the negative slopes and tended to be zero for an inclination angle of about −30°, where no stationary bed was observed.

Experimental and numerical investigation on the influence of rotational speed and particle size on wear of hydro turbine steel

The hydro-electric power plants located in the Himalayan region suffer huge economic losses due to erosion occurring in turbine blades. The main cause for the erosion of turbine blades is the presence of high silt concentration in the rivers of Himalayan region. In the present paper the computational fluid dynamics code CFX is used for numerical erosion modelling of a rectangular shaped work-piece of hydro turbine material (ASTM A182 Stainless steel) in the water-sand slurry mixture in a slurry erosive wear tester. The numerical results are validated with experimental data. The rotational speed of the work-piece is varied from 300 to 700 rpm at solid concentration of 20%. The sand particles of three different sizes 100, 200 and 300 µm are used. It is found that mass loss increases with the increase in rotational speed and size of silt particles. The particles of size 300 µm have a dominating effect on the mass loss of work-piece at the rotational speed of 700 rpm. It is also observed that erosion results predicted by Grant-Tabakoff erosion model agree well with experimental results.

Erosion–Wear Behaviors of High-Chromium Cast Iron with High Nitrogen Content in Water–Sand Slurry and Acid–Sand Slurry

High-chromium cast iron with high nitrogen content (HNHCCI) was prepared using a vacuum induction barotropic furnace, and the erosion–wear behaviors of HNHCCI were investigated with a rotary erosion–wear tester. Results show that most of the nitrogen in HNHCCI dissolves into the matrix and some nitrogen forms carbonitride in the solidification process. The relative wear resistance of HNHCCI can reach 1.34 times that of high-chromium cast iron. The erosion–wear morphologies are ploughing, indentation, and large chips in water–sand slurry, whereas it is galvanic corrosion and carbide fracture in acid–sand slurry. HNHCCI has better mechanical properties and corrosion resistance than HCCI, decreasing the synergism of corrosion and wear. Therefore, HNHCCI has a lower erosion–wear rate.

Erosion wear performance of Ni-Cr-O and NiCrBSiFe-WC(Co) composite coatings deposited by HVOF technique

Purpose This study/paper aims to investigate the erosion wear performance of Ni-based coatings [Ni-Cr-O and NiCrBSiFe-WC(Co)] under sand-water slurry conditions. Design/methodology/approach A high-velocity oxy-fuel (HVOF) process was used to deposit the Ni-based coatings [Ni-Cr-O and NiCrBSiFe-WC(Co)] on the surface of stainless steel (SS 316L) substrate. A Ducom TR-41 erosion tester was used to conduct the tribological experiments on bare/HVOF coated SS 316L. The erosion wear experiments were carried out for different time durations (1.30-3.00 h) at different impact angles (0-60°) by running the pot tester at different rotational speeds (600-1,500 rev/min). The solid concentration of sand slurry was taken in the range of 30-60 Wt.%. The surface roughness of Ni-based coated surfaces was also measured along the transverse length of the specimens. Findings Results show the arithmetic mean roughness (Ra) values of Ni-Cr-O and NiCrBSiFe-WC coated SS-316L were 7.04 and 6.67 µm, respectively. The erosion wear SS-316L was almost 3.5 ± 1.5 times greater than that of the NiCrBSiFe-WC coatings. NiBCrSi-WC(Co) sprayed SS-316L showed lower erosion wear than Ni-Cr-O sprayed SS-316L. Microscopically, the eroded Ni-Cr-O coating underwent plowing, microcutting and craters. Ni-Cr-O coating have shown the ductile nature of erosion wear mechanism. NiBCrSi-WC(Co) surface underwent craters, plowing, carbide/boride pullout, fractures and intact. Erosion wear mechanisms on the eroded surface of NiBCrSi-WC(Co) were neither purely ductile nor brittle. Practical implications It is a useful technique to estimate the erosion wear of hydraulic machinery coated with Ni-based coatings imposed under mining conditions. Originality/value The erosion wear performance of HVOF-sprayed Ni-Cr-O and NiCrBSiFe-WC(Co) powders was investigated through extensive experimentation, and the results are well supported by scanning electron micrographs and 3D topology.

Modeling of Erosion Wear of Sand Water Slurry Flow through Pipe Bend using CFD

Modeling of Erosion Wear of Sand Water Slurry Flow through Pipe Bend using CFD

EVALUATION OF WAVE ATTENUATION BY FLEXIBLE CONTAINER BREAKWATER

A flexible container breakwater FCB, is made of a flexible membrane which filled with sand-water slurry. It is proposed for use in shallow water to attenuate wave energy in non-frequent storm sites and as temporary deployments, instead of costly traditional breakwaters. Experimental studies were carried out under irregular waves mainly in a wave flume and another limited runs in a wave basin. The purpose is to evaluate FCB stability criteria and wave dissipation capabilities. Filling the FCB with slurry with 40% sand was found safe enough against floatation forces. Also, It keeps the system in position under subaerial condition at Hs=1.50 m &Tp=5.5 s and Hs=1.9 & Tp=7.0 s waves according to the FCB bottom contact width. For higher waves, it need be moored by a belt in which the maximum total force is estimated as 2% of its net weight under subaerial conditions and 4% under submergence ratio 0.15. The dissipation coefficient, within the tests program, reached to 80%. Finally, important parameters affecting the efficiency were discussed and its range of applications was proposed.

Settling slurry flow near deposition velocity in inclined pipe of negative slope

Pipe flow of sand-water slurry (settling slurry) is sensitive to pipe inclination. The effect of the angle to which the partially stratified flow is inclined from the horizontal has been subject to investigation in numerous studies. However, almost all of them focus on ascending flows, i.e. flows inclined to positive angles of inclination. It is well known that settling slurry flows inclined to negative slopes (descending flows) differ from those inclined to positive slopes, particularly at velocities near the deposition limit. The deposition limit velocity is the flow velocity at which stationary deposit starts to be formed at the bottom of the pipe. We investigate the effect of the negative slope on pipe flow near deposition limit velocity in the broad range of inclination angles. Besides the deposition limit, we focus on the distribution of solids across the pipe cross section. We combine experimental approach with mathematical modelling. Our new experiments with medium-to-coarse sand (mass-medium grain size 0.87 mm) in a 100-mm pipe inclined from 0 to -45 degree provide suitable data for a validation of predictions of our layered model for partially stratified flows in inclined pipes.

Numerical Analysis of Sand-Water Slurry Flow through Horizontal Pipeline for Various Particle Size at High Velocity

Numerical Analysis of Sand-Water Slurry Flow through Horizontal Pipeline for Various Particle Size at High Velocity

Modeling of sand-water slurry flow through horizontal pipe using CFD

Abstract The paper presents three-dimensional CFD analysis of two-phase (sand-water) slurry flows through 263 mm diameter pipe in horizontal orientation for mixture velocity range of 3.5-4.7 m/s and efflux concentration range of 9.95-34% with three particle sizes viz. 0.165 mm, 0.29 mm and 0.55 mm with density 2650 kg/m3. RNG k-ε turbulence closure equations with Eulerian multi-phase model is used to simulate various slurry flows. The simulated values of local solid concentration are compared with the experimental data and are found to be in good agreement for all particle sizes. Effects of particle size on various slurry flow parameters such as pressure drop, solid phase velocity distribution, friction factor, granular pressure, turbulent viscosity, turbulent kinetic energy and its dissipation have been analyzed.

Heat and mass transfer in three phase fluidized bed containing high density particles at high gas velocities

In a batch gas–liquid contactor, gas holdup in two phase (liquid–gas) and three phase (gas–liquid–solid) fluidized bed has been measured experimentally; bubble size and the corresponding interfacial area of contact between the gas phase and liquid phase were calculated. Mass and heat transfer coefficients were evaluated at different solid contents and variable gas superficial velocities for the cooling and humidification of air bubbles into a water-sand slurry under fluidization conditions. Simplified models were derived to estimate the transfer coefficients.Within the present range of parameters studied, the presence of solid particles decreased the gas holdup as well as the interfacial area of contact between gas and liquid, while both the heat and mass transfer coefficients increased several times compared to the two phase (liquid–gas) values by a factor ranging from 2 to 5 depending on the solid contents and the gas superficial velocity. Applications of the present results in the design and operation of multiphase reactors were highlighted.

Improvement in the Wear Resistance of Brass Impeller of Slurry Pump used in Variation of Operating Speeds

Erosion wear is recognized as an engineering problem for Centrifugal slurry pumps it plays an important role in design and operation of slurry transportation systems. In most slurry pump applications the monetary loss due to pump failure consists of loss of production rather than the cost of the pump, since the process must be shut down when the pump fails. If the erosion rate can be estimated, the pump’s impeller can be changed out in time, during scheduled maintenance, The present work reports experimental investigations on dependence of erosion wear of brass alloys in sand water slurry. Systematic study on the failing impeller of a slurry pump used in irrigation has been carried out by means of scanning electron microscopy in order to clarify the failure mechanisms. The results show .The weight loss of the impeller due to the material removal from the impeller as result of erosion wear. In this investigation, experiments were carried out to evaluate the wear resistance using wear test rig designed and manufactured for this purpose. Three specimens of different brass alloys were used, namely (CuZn2Ge-CuZn4Ge-CuZn6Ge) Discs manufactured from. The accumulated loss of weight was measured and the wear rates were determined for each Case material at constant normal test load of 20kg and time24hr. Number of revolutions of tests equals (10001500-2000) r.p.m. were selected for the three test materials respectively during wear tests .The accumulated loss of weight was measured as a function of the number of revolutions. Wear rate was calculated. The results show Wear rate for material B3 (CuZn6Ge) is less than that of the wear rate for B2 (CuZn4Ge), B1 (CuZn2Ge) under the same testing conditions at (1000-1450-2000) r. p. m.

Improved CFD modeling and validation of erosion damage due to fine sand particles

Using an Eulerian–Lagrangian approach, numerical erosion modeling of a 90° sharp bend in water–sand slurry flow is performed. The numerical results are validated with experimental data in the literature [1]. Two different sand types, 25µm sharp silica sand and 256µm rounded quartz are used. The carrier fluid velocity is varied from 15.2m/s to 26.2m/s. The total mass loss and local wall thickness loss in upstream and downstream sections of the sharp bend are calculated and compared with experimental data. Two models are employed for resolving the near wall region, standard wall-function and low-Re number approach. It is found that for large particles (256μm) the erosion results predicted by both models agree well with experimental data. However, using the standard wall function for small particles (25μm) produces non-physical particle trajectory near the wall. This leads to over prediction of experimental data by about one order of magnitude. The numerical results show that adequately resolving the near wall region and employing the low-Re number model can significantly improve the erosion prediction resulting from small particles.