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Experimental investigation is conducted to study the flow characteristics of a 2-phase vertically upward hydraulic transport of 2 types of small solid particles of nearly identical specific gravity and size in a clear, smooth-surfaced, PVC pipe of I-in (2.54 cm) diameter: Irregular-shaped silica sands and equivalent spherical glass beads. The emphasis of the investigation is placed on the shape effect of particles on the pressure gradients and flow rates. Pressure drops and mass as well as volumetric flow rates were measured by 2 types of flowmeters: electromagnetic (EM) flowmeter and mass flowmeter. The particle sizes used are 30–40 mesh and 8–10 mesh. The results over a turbulent flow range of 10< Re < 10 show the pressure gradients or friction factors are smaller for the spherical glass beads than the irregular-shaped sands. The larger the size of particles is, the larger the shape effect on the pressure gradient becomes, and the more distinct the effect of the particle shape becomes at lower particle concentrations. The larger the size and concentration of the particles are, the larger the pressure gradients become. The larger the particle concentration is, the less the effect of particle shape on pressure gradients becomes. The shape effect is greater for the minimum particle transport velocities than for the settling velocities. INTRODUCTION The present experiment series is to investigate various effects for vertical 2-phase mixture transport and flow characteristics of the particle-water mixture. Its ultimate purpose is to model a vertically upward hydraulic transport system to produce solid particles or solids in alluvial form, including heavy mineral particles from the deep-ocean floor. The present results come from one of the first series of experiments with a 1-in-diameter test loop. Among the many experiments of the vertical particle-water mixture flows that were previously conducted for the vertical hydraulic transport of solid particles,
Determination of Distributions of Velocity And Concentration of Solids In a Horizontal Slurry Pipeline With a Digital Video Camera System
Sato, Hiroshi (Akita University) | Cui, Yushun (Akita University) | Sugimoto, Fumio (Akita University) | Tozawa, Yoshihisa (Akita University) | Hase, Kazunori (Sumiko Consultant Co. Inc.)
This paper reports measurements of particle velocities and concentrations in circular and rectangular conduits by means of a high-grade digital video camera and a stroboscopic lamp. The distributions of the velocity and the concentration are determined by image processing for the motion of solid particles. The results are discussed in terms of the criterion for the identification of particles on the images and the dependence of the velocity distribution on the concentration distribution. INTRODUCTION For the more effective design of transporting settling slurry through pipes, a precise determination of the distributions of the concentration and velocity in the whole flow section is essential. Pressure drops and critical deposit velocities in pipes are important parameters and are dependent on such distributions (Roco and Shook, 1985; Sato et al., 1991). Some measuring systems for determining local particle velocities and/or concentrations have been conducted by Newitt et al. (1962), Ayukawa (1972), Brown et al. (1983), and Nasr-EI-Din et al. (1986). Furthennore, models of theoretical prediction have been proposed in predicting the concentration distributions (Roco and Shook, 1984, 1987; Gillies and Shook, 1994; Sato et al., 1997). In most of the reports, however, one could not compare experimental data of the concentration distribution with those of velocity distribution in the corresponding flow conditions in pipes. The absence of a broad base of experimental data of a pair of distributions of the velocity and the concentration from previous studies prompted the experimental work in this paper. Experiments were performed in l-in transparent pipe connected to a rectangular channel 248 cm × 248 cm and 2 m in length with sand slurries. A high-grade digital video camera was positioned at the return pipe of a closed loop where conditions were sufficiently stable for the testing period.
- Media > Photography (1.00)
- Energy > Oil & Gas > Upstream (1.00)
Norwegian oil companies, research institutes, cable manufacturers and pipeline installation companies are presently conducting studies and a full scale test on electrical heating of multiphase subsea pipelines to prevent hydrate formation (Plugs) during planned shut-downs or reduced flow rate. Traditional methods of clearing pipelines of wax and hydrate deposits are by use of chemical inhibitors. This method is expensive and represents a risk to the environment should leakage occur. Electrical heating is therefore attractive. The Direct Electrical Heating System consists of a feeder cable installed piggy back to the pipeline subject to be heated. This feeder cable is connected to one end of the pipeline and a return cable is connected to the other end. The feeder and return cables are connected to the topside dedicated power supply equipment through a cable riser section. All cables are based on field proven underwater and offshore cable technology. The water depth limitation with current cable and connector technology" is approximately 500 m. Further development can make it feasible to install such a system down to 2000 m water depth. The system can be installed on new subsea developments and it can be retrofitted to existing pipelines. The evaluation of technical feasibility and cost estimates have been completed for a 50 Hz direct resistive heating system. The electrical rating of the system depends on the heat requirement, pipe material and the pipe length. The feasibility of the concept has been verified through full scale subsea tests. Results from the measurements are used to determine the characteristics parameters of the system on fields in the North Sea. The study includes both carbon steel, duplex steel and martensitic steel (13%Cr.). The heat requirement mainly depends on the thermal conductivity of the pipe insulation and seabed soil / gravel, and in the case of melting plugs, the heat capacity of the pipe, thermal insulation and the hydrate must also be taken into consideration.
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Risers (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Offshore pipelines (1.00)
- Facilities Design, Construction and Operation > Offshore Facilities and Subsea Systems (1.00)
- (3 more...)
ABSTRACT Nonlinear interaction between surface waves and a submerged slender body is investigated. In the simulation, the incident waves are generated by a paddle type wavemaker. The fully-nonlinear, viscous, wave-body interaction problem is solved using a boundary-fitted coordinates based finite-difference method. Results are obtained for a range of parameters, with particular emphasis on that of small body-submergence and large-amplitude incident waves. In such highly-nonlinear cases, generation of breaking waves and strong free-surface vorticity layers are observed. Time-averaged hydrodynamic force reveal a negative drift force when the body is close to the free surface. Effect of wave motion on the transport of vortical structures is found to be significant in the presence of long incident waves. INTRODUCTION Prediction and control of motion response to ocean waves is crucial to efficient operation of autonomous underwater vehicles (AUV) in shallow-water environments. Existing controller algorithms were however developed based on somewhat crude hydrodynamics models. These models approximate the hydrodynamic forces using hydrodynamic coefficients that do not properly take into account the free-surface and sea-bottom effects on the dynamics of the vehicle. With the current interest in AUV applications focussed on littoral shallow-water regions, there is a good reason for fully understanding AUV-wave interactions. Even when in deep water, an AUV has to continually approach the surface to seek satellite GPS fixes for the purpose of navigation. Such AUV applications, besides prediction of ship motion in high seas and identification of submerged objects based on free-surface signature and far-field flow structures, are the motivating factors for the present research. In traditional naval hydrodynamics, the linearized problem of wave-body interactions is decomposed into wave incidence, diffraction and radiation problems for analysis in the frequency domain (see, e.g., Newman, 1977). The diffraction and radiation problems have similar mathematical structure, in that both have to satisfy the Sommerfeld radiation condition at infinity.
ABSTRACT A method to evaluate structural durability and performance of windows for use at the U.S. South Pole Station, Antarctica, is developed. Four commercial windows were mounted on a special test chamber simulating the antarctic conditions. The windows were instrumented with heat flux sensors, thermocouples, and strain gauges. The superiority of one product against the other was established on the basis of frost buildup, maintainability of thermal insulation, and structural integrity. INTRODUCTION The objective of this study is to comparatively evaluate, at extremely low temperatures, the performance of three different prototype commercial windows containing polymeric composite components. The evaluation consists of exposing them to a severe thermal gradient, 24°C on one side and _70°C on the other; this closely resembles conditions prevalent at the U.S. Amundsen-Scott South Pole Station, Antarctica. The scope of the work precluded critically analyzing any specific design features that would contribute to superior window performance at extreme temperatures. In general, window frames constructed with polymeric composite materials are an attractive alternative to metallic frames because of their low thermal conductivity, light weight, and lower susceptibility to corrosion. However, polymeric composites are a relatively new class of materials, and not much data about their durability and performance are available, especially under severe environmental conditions. The use of composites for window frames is a developing technology. Data obtained at low temperatures (Dutta 1996), however, show that they may degrade when cold cycled. In windows, several different materials, such as plate glass, metallic or fiber reinforced plastic (FRP) composite frames, and sealing materials are designed to fit closely together Their coefficients of thermal conductivity and thermal expansion are different. This may cause either the failure of the components, or degradation of performance over time. The current investigation is an effort to assess such degradation, if any.
- Antarctica > Antarctica (0.45)
- North America > United States (0.28)