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J.f. Richardson - One of the best experts on this subject based on the ideXlab platform.
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Slurry flow: Principles and practice
International Journal of Multiphase Flow, 2003Co-Authors: J.f. RichardsonAbstract:7.9 Interpreting Experimental Headlosses. Slurry Flow: Principles and Practice describes the basic concepts and methods for understanding and designing slurry flow systems, in-plan installations, and long-distance transportation systems. The goal of this book is to enable the design or plant engineer to derive the maximum benefit from a limited amount of test data and to generalize operating experience to new situations. Design procedures are described in detail and are accompanied by illustrative examples needed by engineers with little or no previous experience in slurry transport. The technical literature in this field is extensive. Front Cover; Slurry Flow: Principles and Practice; Copyright Page; Table of Contents; Preface; Chapter 1. Basic Concepts for Single-Phase Fluids and Particles; 1.1 Steady Pipe Flow; 1.2 Turbulent Pipe Flow; 1.3 Particle Size Distributions; 1.4 Packing of Solid Particles in Containers; 1.5 Forces Acting on a Single Particle in a Dilute Suspension; 1.6 Drag Force on Immersed Objects; 1.7 Relaxation Time; 1.8 Lift Force on a Rotating Particle (Magnus Force); 1.9 Fluid Inertia Effect; 1.10 Brownian Diffusion; 1.11 Electromagnetic Body Forces; 1.12 Heat and Mass Transfer to or from Spheres. 1.13 Surface Forces Between Dispersed Particles1.14 Particle Rotation; Chapter 2. Fluid-Particle Mixtures; 2.1 Definitions for Slurry Flows; 2.2 Conservation Equations for One-Dimensional Flows; 2.3 Multiparticle Drag Relationships; 2.4 Forces in Transient Flows; 2.5 Settling of Monodisperse Suspensions; 2.6 Flocculated Slurries; 2.7 Fluidization of Monodisperse Mixtures; 2.8 Multispecies Systems; 2.9 Particle-Particle Forces in the Momentum Equation; 2.10 Stresses in Flowing Granular Solids; 2.11 Liquefaction and Compaction; 2.12 Pressure Wave Propagation; Chapter 3. Homogeneous Slurries. 3.1 Homogeneity3.2 Shear in Pipe Flow; 3.3 Shear in an Annulus; 3.4 Integrated Equations for Viscometric Flows; 3.5 Newtonian Slurries; 3.6 Distribution Effects; 3.7 High Solids Concentrations; 3.8 Particle Shape; 3.9 Electroviscous and Surface Effects; 3.10 Yield Stresses; 3.11 Shear Thinning; 3.12 Time Dependence; 3.13 Shear Thickening; 3.14 Emulsions; 3.15 Drag Reduction; 3.16 Fiber Suspensions; 3.17 Oscillating and Falling-Ball Viscometry; Chapter 4. Calculations for Homogeneous Flows; 4.1 Concentric Cylinder Viscometry; 4.2 Tube Viscometry; 4.3 Wall Slip and Nonhomogeneous Flow. 4.4 Turbulent Flow4.5 Slurries Containing Coarse Particles; 4.6 Laminar-Turbulent Transition; 4.7 Scaleup Using Turbulent Flow Data; Chapter 5. Correlations for Nonhomogeneous Slurries; 5.1 Introduction; 5.2 Deposition Velocity; 5.3 Headloss Correlations for Horizontal Flow; 5.4 Broad Size Distributions; 5.5 Regime-Specific Correlations; 5.6 Turian-Yuen Correlation; 5.7 Vertical Flows; 5.8 Velocity and Concentration Effects in Vertical Flow; 5.9 Minimum Velocity for Vertical Flow; 5.10 Mean Density from Pressure Drop; 5.11 Inclined Pipes; Chapter 6. The Two-Layer Model. 6.1 Origin of the Model6.2 The Two-Layer Model; 6.3 Sample Calculation: Two-Layer Model; 6.4 Developments in the Model; 6.5 Effects of Particle Diameter and Fluid Viscosity; 6.6 Inclined Flows; 6.7 Inclined Pipes at Shutdown; 6.8 Deposition and the Model; Chapter 7. Microscopic Modeling of Slurry Flows; 7.1 The Need for Models; 7.2 Concentration Distributions in a Closed Channel; 7.3 The Diffusion Model; 7.4 Fine-Sand Concentration Distributions; 7.5 Coarse-Sand Concentration Distributions; 7.6 Modifying the Diffusion Model; 7.7 Velocity Distributions; 7.8 Modeling Velocity Distributions.
B.d. Rothfuss - One of the best experts on this subject based on the ideXlab platform.
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TBM Tunnel Friction Values for the Grizzly Powerhouse Project
1995Co-Authors: Richard D. Stutsman, B.d. RothfussAbstract:Tunnel boring machine (TBM) driven water conveyance tunnels are becoming increasingly more common. Despite advances in tunnel engineering and construction technology, hydraulic performance data for TBM driven tunnels remains relatively unavailable. At the Grizzly Powerhouse Project, the TBM driven water conveyance tunnel was designed using friction coefficients developed from a previous PG&E project. A range of coefficients were selected to bound the possible hydraulic performance variations of the water conveyance system. These friction coefficients, along with the water conveyance systems characteristics, and expected turbine characteristics, were used in a hydraulic transient analysis to determine the expected system pressure fluctuations, and surge chamber performance. During startup test data, these performance characteristics were measured to allow comparison to the original design assumptions. During construction of the tunnel, plaster casts were made of the actual excavated tunnel unlined and fiber reinforced shotcrete lined surfaces. These castings were used to measure absolute roughness of the surfaces so that a friction coefficient could be developed using the Moody diagram and compare them against the design values. This paper compares the assumed frictional coefficient with computed coefficients from Headlosses measured during startup testing, and plaster cast measurement calculations. In addition, a comparison of coefficients will bemore » presented for an other TBM driven water conveyance tunnel constructed in the 1980`s.« less
Richard D. Stutsman - One of the best experts on this subject based on the ideXlab platform.
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TBM Tunnel Friction Values for the Grizzly Powerhouse Project
1995Co-Authors: Richard D. Stutsman, B.d. RothfussAbstract:Tunnel boring machine (TBM) driven water conveyance tunnels are becoming increasingly more common. Despite advances in tunnel engineering and construction technology, hydraulic performance data for TBM driven tunnels remains relatively unavailable. At the Grizzly Powerhouse Project, the TBM driven water conveyance tunnel was designed using friction coefficients developed from a previous PG&E project. A range of coefficients were selected to bound the possible hydraulic performance variations of the water conveyance system. These friction coefficients, along with the water conveyance systems characteristics, and expected turbine characteristics, were used in a hydraulic transient analysis to determine the expected system pressure fluctuations, and surge chamber performance. During startup test data, these performance characteristics were measured to allow comparison to the original design assumptions. During construction of the tunnel, plaster casts were made of the actual excavated tunnel unlined and fiber reinforced shotcrete lined surfaces. These castings were used to measure absolute roughness of the surfaces so that a friction coefficient could be developed using the Moody diagram and compare them against the design values. This paper compares the assumed frictional coefficient with computed coefficients from Headlosses measured during startup testing, and plaster cast measurement calculations. In addition, a comparison of coefficients will bemore » presented for an other TBM driven water conveyance tunnel constructed in the 1980`s.« less
Rebecca Glaser - One of the best experts on this subject based on the ideXlab platform.
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Common Pitfalls in Hydraulic Design of Large Diameter Pipelines: Case Studies and Good Design Practice
Pipelines 2011, 2011Co-Authors: David Bennett, Rebecca GlaserAbstract:When designing large diameter water transmission pipelines, some engineers rely on design rules-of-thumb or a previous project as a template, without recognizing the inherent differences of each project. For large-scale water supply projects, mistakes in hydraulic design, especially underestimating friction Headlosses, can be magnified resulting in reduced system capacities, catastrophic failures, or potential litigation. One of the most common mistakes in hydraulic design of large-diameter pipelines is underestimating pipe resistance and friction Headlosses. The Hazen-Williams equation is the most widely used method for calculating Headlosses in pipelines because it is simple and easy to use. However, the Hazen-Williams equation is empirical and, for large-diameter pipelines, has a limited range of applicability. Conversely, the Darcy-Weisbach equation provides a better approximation of friction Headlosses since it takes into account the pipe roughness and Reynolds Number for different pipe materials, and is valid for all pipe sizes and turbulent flow ranges. Although there is an abundance of evidence of the limitations of the Hazen-Williams equation, it is continually misused in the engineering industry. There are many other design issues that can cause serious performance problems with large-diameter pipeline projects if not taken into consideration during design. Additional common hydraulic design pitfalls include: underestimating effects of sediment and biological material in raw water sources, not accounting for aging of pipeline materials, inadequate pipe pressure class design, improper placement and sizing of air valves, lack of accurate transient and surge analysis, inadequate flow and pressure field measurement, and potential need for pipeline maintenance and cleaning. There have been numerous publications on the topic of hydraulic design and proper calculation of pipeline friction Headlosses. However, the focus of this paper is to provide analysis through case studies of several major water supply systems that reaffirms the importance of utilizing proper hydraulic considerations. Common hydraulic design oversights and short-cuts can often result in capacity and maintenance problems for large water supply systems.
Rikard Strand - One of the best experts on this subject based on the ideXlab platform.
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Experimental studies on intake headloss of a blasted lake tap
IOP Conference Series: Earth and Environmental Science, 2014Co-Authors: James Yang, Mats Billstein, Fredrik Engstrom, Rikard StrandAbstract:In existing reservoirs, construction of an intake is sometimes achieved by so-called lake tapping, a submerged tunnel piercing by blasting out the rock plug at the intake. The blasting process involves phases of rock, water, air and gas released from the explosive charge; the resulting entrance profile often differs from design assumptions. The intake headloss is a factor of concern for power generation. For a vertical intake formed by lake tapping, experiments have been carried out in a 1:30 physical model to examine the effect of entrance shapes on intake Headlosses. The purpose is that, if there is potential to reduce the Headlosses, the originally blasted intake shape would be modified. In the model, five alternative shapes are evaluated. The test results show that to enlarge the vertical shaft area is the most effective way to reduce the intake headloss; to further blast out a narrow channel upstream does not give much effect. Bearing in mind the risk of free-surface vortex at the intake, the influence of the intake modifications on vortex is also checked.
