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Effect of pipe inclination on the pipe flow head losses for
Effect of pipe inclination on the pipe flow head losses for
Effect of pipe inclination on the pipe flow head losses for
Effect of pipe inclination on the pipe flow head losses for
Effect of pipe inclination on the pipe flow head losses for
Effect of pipe inclination on the pipe flow head losses for
Effect of pipe inclination on the pipe flow head losses for
Effect of pipe inclination on the pipe flow head losses for
Effect of pipe inclination on the pipe flow head losses for
Effect of pipe inclination on the pipe flow head losses for
Effect of pipe inclination on the pipe flow head losses for
Effect of pipe inclination on the pipe flow head losses for
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Effect of pipe inclination on the pipe flow head losses for

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  • 1. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 3, May - June (2013), © IAEME45EFFECT OF PIPE INCLINATION ON THE PIPE FLOW HEADLOSSES FOR DIFFERENT SAND CONCENTRATIONSMahmoud Ali Refaey EltoukhyFaculty of Engineering, Shobra, Banha University, EgyptABSTRACTThis paper presents results of an experimental study pertaining to the behavior ofsand-water (two-phase) flows in inclined pipes, a phenomenon that is generally witnessed atthe canal intakes which aligned at desert area, and dredging processes. The experiments wereconducted in a modern hydraulics laboratory to study the effect of sand concentration andpipe inclination on the pipe flow head losses. The pipe inclination angle was varied from 0°to 90° in upward and downward directions and the sand concentration in water was regulatedup to 15% by volume. It was concluded that the head losses of the downward sloping pipeflow are always lower than the head losses of the horizontal flow and these are always lowerthan the head losses of the upward sloping pipe flow, regardless of the concentration andinclination angle. The experiment results were analyzed in the light of earlier published dataand useful empirical correlations have been developed to determine the head losses ofhorizontal flow, alongwith upward and downward sloping pipe flows.Keywords: head loss, sand - water mixture, inclined pipes, sand concentrationINTRODUCTIONMost of the applications of hydraulic transport in the past have been in the mineralsindustries. Generally, such industrial facilities are located in remote areas with insufficientroad or rail infrastructure. Therefore, pipeline transport has been preferred and recognized asthe most cost effective method of transporting huge quantities of minerals over longdistances, across difficult terrain. The solid particles invariably being heavier than theconveying liquid are transported in lower part of the channel. This unique pattern has been asubject of special study and is presented in this paper. The effect of flow velocity, sandconcentration and the sloping pipe inclination angle on the head loss were investigated. TheINTERNATIONAL JOURNAL OF CIVIL ENGINEERING ANDTECHNOLOGY (IJCIET)ISSN 0976 – 6308 (Print)ISSN 0976 – 6316(Online)Volume 4, Issue 3, May - June (2013), pp. 45-56© IAEME: www.iaeme.com/ijciet.aspJournal Impact Factor (2013): 5.3277 (Calculated by GISI)www.jifactor.comIJCIET© IAEME
  • 2. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 3, May - June (2013), © IAEME46head losses determined for the horizontal portion of the pipeline were compared withcorrelations found in the literature. A pipe loop system was built, allowing variation of flowvelocity, sand concentration and pipe inclination.OVERVIEW OF THE PRIOR PUBLISHED DATAWasp et al., (1999) found that the flow of solid-liquid slurries in pipes differs from theflow of homogeneous liquids in a variety of ways. The complete range of velocities ispossible with liquids, whereas nature of the flow, i.e., laminar, transition, or turbulent, can becharacterized based on the knowledge of physical properties of the fluid and the pipe system.The characterization of slurry flow is not as simple as for liquid flow mainly for two reasons:firstly the properties of the solid particles to be accounted for are superimposed on theproperties of the liquid, and also the effect of the particles on the mixture properties;secondly, depending on the particular conditions, a range of slurry behavior is possible.Kaushal et al (2005), and Kaushal and Tomita (2007) carried out experimental study forconcentration of distributions in slurry pipeline by using γ- ray densitometer. Theirmeasurements show that, pressure gradient profiles of equivalent fluid for finer particles werefound to resemble with water data except for 50% concentration, however, more skewedpressure gradient profiles of equivalent fluid were found for coarser particles. Experimentalresults indicate absence of near-wall lift for finer particles due to submergence of particles inthe lowest layer into the viscous sub layer and presence of considerable near-wall lift forcoarser particles due to impact of viscous-turbulent interface on the bottom most layer ofparticles and increased particle–particle interactions.Richardson, et al., (1999) found that, in homogenous flow systems, the presence ofthe solids can have a significant effect on the system properties, usually resulting in a sharpincrease in viscosity as compared to that of the carrier fluid. In heterogeneous flow systems,solids are not evenly distributed and in horizontal flow, pronounced concentration gradientexists along the vertical axis of the pipe, even at high velocities. Particle inertial effects aresignificant, i.e., the fluid and solid phases to a large extent retain their separate identities, andthe increase in the system viscosity over that of the carrier liquid is usually quite small.Heterogeneous slurries tend to be of lower solid concentrations and have larger particle sizesthan homogeneous slurries. Raudkivi, (1989), found that in vertical pipes the velocity ofsolids for upward flow is less than the fluid velocity, but is greater for downward flow. Thedifference is approximately the value of the settling velocity.Coiado and Diniz, (2001), studied the solid-water flow in inclined pipes. Based on thecollected experimental data, the adopted methods and the experimental conditions, it wasconcluded that the head losses values for the downward sloping pipes are always lower thanthe head losses for the horizontal pipe, and these are always lower than the head losses for theupward sloping pipes, regardless of the inclination angles and concentrations. Whereas, incase of downward sloping length of water-sand slurry flow, the presence of sand decreasesthe head losses values corresponding to the inclination angle and increasing concentration.C. Kim et al, (2008), made an experimental study on the transport of sand-watermixtures in circular and square pipelines, focusing on the economic transport of solidparticles. The measured data of the hydraulic gradient, solid effect, and deposition-limitvelocity for both circular pipe and square duct were compared and analyzed. The hydraulicgradient of water in the circular pipe was found larger than that in the square duct because ofthe secondary flow in the square duct. The hydraulic gradient of sand-water mixture in the
  • 3. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 3, May - June (2013), © IAEME47square duct was larger than that in the circular pipe. It was found that the hydraulic gradientof the slurry flow in the circular and square pipelines increases with the volumetric deliveredconcentration and Reynolds number.D.R. Kaushal, et al, (2012), simulated Pipeline slurry flow of mono- dispersed fineparticles at high concentration numerically using Mixture and Eulerian two-phase models. Itwas found that, pressure drop predictions by both MIxture and Eulerian two-phase models forflow of water show good agreement with the experimental data. Whereas, in case ofcomparison between measured and predicted pressure drops at different concentrations,namely, 30%, 40% and 50%, the Mixture model fails to predict pressure drops correctly, theamount of error increasing rapidly with the concentration. However, Eulerian model givesfairly accurate predictions for pressure drop at all the efflux concentrations and for flowvelocities considered in the present study.The published materials about two-phase (solid-liquid) flow are mostly related tohorizontal pipe flow. There are a limited number of studies concerning the effect of pipeinclination on two-phase flow energy loss. In htis backdrop, this paper studies the effect ofthe pipe inclination on the pipe flow head losses for different sand concentrations, andpresents its results in the forms of curves and equations to compute the head loss, given thesand water mixture flow velocity, the pipe angle of inclination, and the sand concentration involume.EXPERIMENTAL APPARATUSThe general layout of the apparatus is shown in Fig. 1. This apparatus is used to reachthe objectives proposed in this paper. It consists of a pipe loop system, and was fabricated inthe professional Hydraulics Laboratory. The sand water mixtures were prepared in the maintank, which had dimensions of 0.80 m length, 0.70 m width, and 0.80 m depth. The mixturewas maintained homogeneous in the main tank by the use of an auxiliary pump. Then, thehomogeneous mixture was pumped, through a pipeline with diameter of 0.75 m. The pipelinewas made up of horizontal and inclined pipes. The head loss measurements for the sand-water mixture flow were carried out in the pipelines. The sand used in the experiment wasuniform with median grain size d50 = 0.20 mm, and relative density of 2.67, withconcentrations 15 % up in volume. The pipe inclination angle used was varied from 0o(horizontal position) to 90o(vertical position), for each upward and downward inclinations.During the sand water mixture flow through the pipeline, for different velocities andconcentrations of the mixture, the following parameters were measured: a) the head losses inthe horizontal, upward, and downward inclinations; b) the discharge; and c) the concentrationof the sand in water. The discharge was measured by dividing a volume of the outlet mixtureby the corresponding time. The concentration of the mixture was determined using a tank tomeasure the volume and one balance. Whereas, the head losses in the horizontal, upward, anddownward sloping lengths were measured by differential manometer.EXPERIMENTAL WORKThe experimental work consists of two main sets of experiments. The first set consistsof 126 runs, and it used to measure the head losses through the upward inclination pipeline atdifferent mixture velocities and for different sand concentrations. The angles of the pipelineinclination were 5o, 10o, 25o, 35o, 45oand
  • 4. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 3, May - June (2013), © IAEME48Rubber pipeTank auxiliary pump main pumpFig. 1. The Apparatus Layout90o. The sand concentrations used for each angle of inclination are 5 %, 10 %, and 15 % involume. The second set of experiments consists of 118 runs, and the pipeline inclinationangles were as that of the first set except that, the pipeline inclination was downward. Fiftyruns were carried out to measure the head losses through the horizontal pipeline at threedifferent sand concentrations. The horizontal pipeline runs results, are analyzed with theupward and downward pipeline inclinations results. In the light of above conclusions, thesand water mixture velocity should be greater than the deposition limit (critical) velocity,which is the mean mixture velocity at the limit of stationary deposition. From Durand (1953)and Gibert (1960) for the used sand, the mixture velocity should be greater than 1.88 m/s inall runs to maintain that the sand particles are always in suspension state.RESULTS AND DISCUSSIONTwo empirical equations were developed to calculate the head losses of the water-sand mixture as a function of flow Frouds number, Fn, the sand concentration, C, and theinclination angle, α, of upward and downward flows in inclined pipes. The equations weredeveloped by several curve fittings. First of all, the apparatus was calibrated throughcomparison of the measured head losses in a horizontal pipeline with that measured by E. M.Coiado, (2001), Fig. (2), which shows that the measured and Coiado results are almostidentical.FLOW THROUGH UPWARD INCLINATION PIPELINEFor the first set of experiments, the sand water mixture was pumped through thepipeline which was laid in upward inclination positions. The used pipeline inclination anglesare 0o(horizontal position), 5o, 10o, 25o, 35o, 45o, and 90o(upward vertical position). Thehead losses were measured in the pipeline in each inclination position for three sandconcentrations, i.e., 5%, 10%, and 15%.
  • 5. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 3, May - June (2013), © IAEME49The results of the flows through upward inclination Pipeline were analyzed. Theeffect of each sand-water mixture velocity represented in Froudes number, Fn, the pipelineangle of inclination, α, and the sandFig. 2. Apparatus Calibration, for C = 10%, and pipe inclination angle 10oupwardconcentration, C on the head losses in the pipeline was developed. It was found that thehydraulic gradient increases with increasing sand water mixture velocity. For example, for C= 10% and α = 35o, if the sand water mixture velocity increases from 3.3 m/s to 5.2 m/s, thehydraulic gradient increases from 0.27 to 0.37, meaning thereby that increase of 57.5% in themixture velocity results in increasing 37% in the hydraulic gradient, as indicated in Fig. (3).Another runs of experiments were carried out through varying the sandconcentrations up to 15%, to study the effect of sand concentration on the head losses inupward pipeline inclination. It was found that increase in the sand concentration results inincreasing hydraulic gradient. For example, for pipeline inclination angle of 25oand sandwater mixture velocity of 3.75 m/s, changing sand concentration from 10% to 15%, thehydraulic gradient changes from 0.21 to 0.265, thereby showing that 50% increase in sandconcentration yields 26% increase in the hydraulic gradient in the pipeline, as shown in Fig.(4).The effect of pipeline inclination angle was studied by changing α from 0o(horizontalpipeline) to 90o(vertical pipeline). Experiments showed that the hydraulic gradient of thepipeline increases as its upward angle of inclination increases, Fig. (5). For example, at sandconcentration C = 10 %, when the upward inclination angle increases from α =10oto 45o, thehydraulic gradient increases from 0.199 to 0.296, implying that increase of 35% in upwardinclination angle of pipeline results into 49% increase in the hydraulic gradient.00.050.10.150.20.250.30.352 3 4 5 6 7Froudes Number, FnHydraulicGradient,(i),PresentCoiado, 2001
  • 6. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 3, May - June (2013), © IAEME50Fig. 3 Variation of the hydraulic gradient with the sand water mixture velocity for C=10% and α = 35oFig. 4 Effect of sand concentration on the hydraulic gradient, for α = 25oand v = 3.75m/s (Upward)00.10.20.30.40.50.62 2.5 3 3.5 4 4.5 5 5.5 6Froudes Number, FnHydraulicgradient(i), α = 0Up 5Up 10Up 25Up 35Up 45Up 9000.050.10.150.20.250.30.350.42 2.5 3 3.5 4 4.5 5 5.5 6 6.5Froudes Number, FnHydraulicGradient,(i),iC = 5 %C = 10 %C = 15 %
  • 7. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 3, May - June (2013), © IAEME51Sin αFig. 5 Effect of the upward pipe inclination angle on the hydraulic gradient, i for C=10%With a view to accomplish the objectives set for this study, several curve fittings weredone and sound relationship was established between hydraulic gradient and the affectingparameters, i.,e., the Froudes number, the pipeline inclination, and the sand concentration,Fig. (6). With parameters factor UPI on the horizontal axis and the hydraulic gradient on thevertical axis:0779.025.0sin1091.00574.0 −−+= CgDvIUP α (1)Where:v : sand water mixture flow velocity, (m/s)α : pipeline angle of inclinationC: sand concentration in water (% in volume).The hydraulic gradient, i , may be calculated for any UPI for a given sand water mixturevelocity, the pipeline inclination angle, and the sand concentration from Fig. (6). Throughcurve fitting for data in Fig. (6), the following equation was obtained:012.00669.1 −= UPIi (2)00.050.10.150.20.250.30.350.40 0.2 0.4 0.6 0.8 1 1.2HydraulicGradient,(i),i
  • 8. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 3, May - June (2013), © IAEME52UPIFig. 6 Upward pipe flow hydraulic gradient variation with the affecting parametersBy substituting the value of UPI from Equation 1 into Equation 2, the hydraulic gradient canbe directly calculated as under:0951.02667.0sin1164.00612.0 −−+= CgDvi α (3)FLOW THROUGH DOWNWARD INCLINATION PIPELINEIn the second set of experiments, the sand water mixture was pumped throughthe pipeline which was laid in downward inclination positions. The study parameterencompassed pipeline inclination angles 0o(horizontal position), 5o, 10o, 25o, 35o, 45o, and90o(downward vertical position). Whereas, all measurements of head losses in the pipelinewere carried out in each inclination position for the three sand concentrations, 5%, 10%, and15%.The results were analyzed to determine the effect of each of sand water mixturevelocity represented in Froudes number, Fn, the pipeline angle of inclination, α, and the sandconcentration, C on the head losses in the pipeline. The sand water mixture velocity effect onthe head loss is shown in Fig. (7). It was found that the hydraulic gradient increases as thesand water mixture velocity increases. For example, for C = 10% and α = 35o, if the sandwater mixture velocity increases from 3.28 m/s to 5.2 m/s the hydraulic gradient increases00.10.20.30.40.50.60 0.1 0.2 0.3 0.4 0.5 0.6HydraulicGradient,(i),i
  • 9. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 3, May - June (2013), © IAEME53Fig. 7 Variation of the hydraulic gradient with sand water mixture velocity for C= 10%and α = 35ofrom 0.024 to 0.175, showing that increase of 58.5% in the mixture velocity results inincrease of 629% in the hydraulic gradient.Another set of experiments was undertaken to study the effect of sandconcentration on head losses in downward pipeline inclination by varying sandconcentrations up to 15%. The results showed that the sand concentration is inverselyproportional with the hydraulic gradient. For example, for pipeline inclination angle of 25oand sand water mixture velocity of 3.75 m/s, changing sand concentration from 10% to 15%,results in changing the hydraulic gradient from 0.0778 to 0.063, showing that 50% increase inthe sand concentration results in 19% decrease in the hydraulic gradient in the pipeline, Fig.(8).Also, the effect of the pipeline inclination angle on the pipeline hydraulic gradientwas studied by changing α from 0o(horizontal pipeline) to 90o(vertical pipeline).Experiments showed that the hydraulic gradient of the pipeline decreases as its downwardangle of inclination increases, Fig. (9). For example, at sand concentration C = 10 %, whenthe downward inclination angle increases from α =10oto 45o, the hydraulic gradientdecreases from 0.129 to 0.048, showing that with downward inclination angle of the pipelineincreasing by 35%, the hydraulic gradient decreases by 63%.The curve fittings were done for this set of parameters as well to determinerelationship between the hydraulic gradient and the affecting parameters, i.e, the Froudesnumber, the pipeline inclination, and the sand concentration, which yielded promising resultsas shown in Fig. (10) and the underlying relationship, taking Parameters factor DwnI on thehorizontal axis and the hydraulic gradient on the vertical axis:00.050.10.150.20.250.30.352 3 4 5 6 7Froudes Number, FnHydraulicGradient,(i),iα = 0Dow 5Dow 10Dow 25Dow 35Dow 45Dow 90
  • 10. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 3, May - June (2013), © IAEME54Fig. 8 Effect of sand concentration on the hydraulic gradient, for α = 25oand v = 3.75m/s (Downward)Sin αFig. 9 Effect of the Downward pipe inclination angle on the hydraulic gradient, i for C=10%00.050.10.150.20.252 3 4 5 6 7Froudes Number, FnHydraulicGradient,(i),i C = 5 %C = 10 %C = 15 %00.020.040.060.080.10.120.140.160.180 0.2 0.4 0.6 0.8 1 1.2HydraulicGradient,(i),i
  • 11. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 3, May - June (2013), © IAEME55DwnIFig. 10 Downward pipe flow hydraulic gradient variation with the affecting parameters1346.015.0sin0675.00585.0 −+−= CgDvIDwn α (4)The hydraulic gradient, i may be calculated for any DwnI for a given sand watermixture velocity, the downward pipeline inclination angle, and the sand concentration. Therelationship established by curve fitting for data in Fig. (10), is given as under:0031.09848.0 += DwnIi (5)The following relationship is obtained by combining Equations (4) and (5), to calculate thehydraulic gradient given the values of sand water mixture velocity, the pipeline inclination,and the sand concentration:1295.0148.0sin0665.00576.0 −+−= CgDvi α (6)00.050.10.150.20.250.30.350 0.05 0.1 0.15 0.2 0.25 0.3 0.35HydraulicGradient,(i),i
  • 12. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 3, May - June (2013), © IAEME56CONCLUSIONSThis paper gives the results of an experimental study undertaken to determine theeffects of sand water mixture velocity, the pipeline inclination angle upward and downward,and the sand concentration on the head loss in the pipeline. Based on the experimental data,the results of curve fitting, and the resulting mathematical expressions, the followingconclusions are reached:1. The head losses for the downward inclination of the pipeline are always lower thanthe head losses for the horizontal pipe, and these are always lower than the headlosses for the upward sloping pipes, regardless of the inclination angles andconcentrations.2. For the downward inclination of the pipeline, the presence of sand decreases the headlosses with increasing inclination angle and the sand concentration.3. For the water-sand mixture flow in the horizontal pipe, the presence of sand increasesthe head losses as the concentration increases.4. For the upward inclination of the pipeline water-sand mixture flow, the presence ofsand increases the values of the head losses with increase in inclination angle and theconcentration.5. The curve fitting results and the corresponding equations developed can be used forcalculating the head loss in the pipeline for given sand water mixture velocity, thepipeline inclination angle, and the sand concentration.REFERENCES1. E. M. Coiado and M. G. Diniz, (2001), "Two-Phase (Solid-Liquid) Flow in InclinedPipes", J. Braz. Soc. Mech. Sci. vol.23 no.3 Rio de Janeiro.2. D.R. Kaushal, T. Thinglas, Y. Tomita, S. Kuchii, and H. Tsukamoto, (2012), " CFDmodeling for pipeline flow of fine particles at high concentration", International Journalof Multiphase Flow 43, 85–1003. Durand, R. (1953), " Basic solids in pipes – Experimental Research", ProceedingsInternational Hydraulics Conference, Minneaplis, MN, pp. 89 – 103.4. Gibert, R. (1960), "Transport Hydraulique et Refoulement des Mixtures en Conduit",Anna1es des Pontes et Chaussees, 130e Annee, No. 12, et No. 17.5. Kaushal D.R., Kimihiko Sato, Takeshi Toyota, Katsuya Funatsu, Yuji Tomita (2005),"Effect of particle size distribution on pressure drop and concentration profile inpipeline flow of highly concentrated slurry", International Journal of Multiphase FlowVolume 31, Issue 7, July 2005, Pages 809–8236. Kaushal, D.R., Tomita, Y., 2007, "Experimental investigation of near-wall lift ofcoarser particles in slurry pipeline using γ-ray densitometer" Powder Tech nol. 172,177–187.7. Raudkivi, A. J., 1989 "Loose Boundary Hydraulics", Pergamon Press, New York8. Richardson, J. F., Chhabra, R. P., Khan, A. R., 1999 "Multiphase flow ou non-Nextonian fluids in horizontal pipes", Slurry Handling and Pipeline Transport.Hidrotransport 14. Maastrich. Netherlands.9. Wasp, E. J.; Kenny, J. P.; Gandhi, R. L. 1999. "Solid-Liquid Flow Slurry PipelineTransportation", Series on Bulk Materials Handling. International Standard BookNumber. Trans Tech Publications. Germany.

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