scholarly journals CFD investigation of internal elbow pipe flows in laminar regime

2021 ◽  
Vol 1201 (1) ◽  
pp. 012012
Author(s):  
R Taibi ◽  
G Yin ◽  
M C Ong
Keyword(s):  
Fluid Transport ◽  
Oil And Gas ◽  
Internal Flow ◽  
Oil And Gas Industry ◽  
Laminar Flows ◽  
Secondary Flows ◽  
Transport Systems ◽  
Centrifugal Forces ◽  
Dean Number ◽  
Curvature Ratio

Abstract Elbow pipes are crucial parts of many fluid transport systems in the oil and gas industry. The curved shape of such pipes induces centrifugal forces on the internal flow, ultimately affecting the flow velocity and creating pressure differences within the elbow. The present study aims to investigate the effects of the curvature ratio of an elbow pipe on the internal pipe flow using three-dimensional numerical simulations. For laminar flows, the simulations are based on four Reynolds numbers ranging from 200 to 2000 and three curvature ratios of Ro=5.6, 11.2 and 22.4. A mesh convergence study is carried out for 3 meshes with increasing resolution. The results based on the optimal mesh is then compared with the published experimental and numerical results for validation. Once the validation is confirmed, further simulation and analysis are performed for each combination of curvature ratio and Reynolds number. The results reveal that there is flow separation due to the centrifugal forces induced by the curved shape. It is also shown that secondary flows consisting of symmetrical helical vortices called Dean vortices are generated. The intensity of this secondary flow is shown to increase with the increasing Dean number.

Maximum Drag Reduction Asymptote of Polymeric Fluid Flow in Coiled Tubing

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Subhash N. Shah ◽  
Yunxu Zhou
Keyword(s):  
Drag Reduction ◽  
Oil And Gas ◽  
Guar Gum ◽  
Oil And Gas Industry ◽  
Flow Loop ◽  
Polymeric Fluids ◽  
Curvature Ratio ◽  
Coiled Tubing ◽  
Industry Applications ◽  
Maximum Drag Reduction

This study experimentally investigates the drag reduction characteristics of the most commonly used polymer fluids in coiled tubing applications. The flow loop employed consists of 12.7mm straight and coiled tubing sections. The curvature ratio (a∕R, where a and R are the radii of the tubing and the reel drum, respectively) investigated is from 0.01 to 0.076, which covers the typical curvature ratio range encountered in the oil and gas industry applications. Fluids tested include xanthan gum, guar gum, and hydroxypropyl guar at various polymer concentrations. It is found that the drag reduction in coiled tubing is significantly lower than that in straight tubing, probably due to the effect of secondary flow in curved geometry. The onset of drag reduction is also found to be delayed as the curvature ratio was increased. A correlation for the maximum drag reduction (MDR) asymptote in coiled tubing is developed. When the curvature ratio is set to zero, the new correlation reduces to the well-known Virk’s MDR asymptote for dilute polymer solutions in straight pipes. A new drag reduction envelope is proposed for the analysis of drag reduction behavior of polymeric fluids in coiled tubing. Application of the new drag reduction envelope is also discussed.

CFD Analysis of the Effect of Rolling Motion on the Characteristic of Labyrinth Seal

2017 ◽  
Author(s):  
Ning Huang ◽  
Zhenlin Li ◽  
Shiyao Li ◽  
Ning Zhang ◽  
Zhihui Dong
Keyword(s):  
Pressure Drop ◽  
Natural Gas ◽  
Performance Characteristic ◽  
Oil And Gas ◽  
Internal Flow ◽  
Oil And Gas Industry ◽  
Labyrinth Seal ◽  
Rolling Motion ◽  
Turbo Expander ◽  
Liquid Natural Gas

With the development of offshore oil and gas industry, LNG turbo expanders are widely used in Floating Liquid Natural Gas equipment (FLNG) for natural gas transportation. The performance characteristic of the turbo expander is significant affected by the rolling motion caused by the ocean conditions. As an important part of expander, the labyrinth seal is directly related to the safety of the expander, so it is necessary to study the performance characteristic of labyrinth seal under rolling motion. In this paper, CFD is used to simulate the internal flow field of labyrinth seals under different rolling periods and sloshing amplitudes conditions. The distribution of the pressure drop is obtained, and the influence of rolling motion on different labyrinth seal radial clearances and cavity depths are discussed. The results indicate that variation periods of the pressure drop are consistent with the rolling periods, and the larger the rolling amplitude is, the larger pressure drop fluctuation can be observed. Additionally, the fluctuation characteristic is significantly affected by gap widths and cavity depths.

scholarly journals Dynamic Characteristics and Stability of Flexible Riser Under Consideration of Non-Uniform Tension and Internal Flow

2020 ◽  
Author(s):  
Dingbang Yan ◽  
Shuangxi Guo ◽  
Yilun Li ◽  
Jixiang Song ◽  
Min Li ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
Oil And Gas ◽  
Internal Flow ◽  
Oil And Gas Industry ◽  
Travelling Wave ◽  
Flexible Riser ◽  
Modal Shape ◽  
Gas Industry ◽  
Uniform Tension ◽  
The Stability

Abstract As oil and gas industry is developing towards deeper ocean area, the length and flexibility of ocean risers become larger, which may induce larger-amplitude displacement of flexible riser response due to lower structural stiffness against environmental and operational loads. Moreover, suffering not only the external fluid loads coming from environmental ocean wave and current, these risers also convey internal flow. In other words, the dynamic characteristics and response of the flow-conveying riser face great challenge, such as bucking, divergence and flutter, because of the fluid-solid coupling of the internal hydrodynamics and riser structural dynamics. In this study the dynamic characteristics and stability of a flexible riser, under consideration of its internal flow and, particularly, non-uniform axial tension, are examined through our FEM numerical simulations. First, the governing equations and FEM models of a flexible riser with axially-varying tension and internal flow are developed. Then the dynamic characteristics, including the coupled frequency and modal shape, are presented, as considering the speed of internal speed changes. At last, the dynamic response and corresponding stability behaviors are discussed and compared with the cases of riser with uniform tension. Our FEM results show that the stability and response are quite different from riser with uniform tension. And, the time-spatial evolution of riser displacement exhibit a strong wave propagation phenomenon where travelling wave are observed.

CFD Analysis of Centrifugal Compressor Stage Range Extension Using Internal Flow Recirculation

2015 ◽  
Author(s):  
Uday K. Meduri ◽  
Kathiravan Selvam ◽  
Gilles Nawrocki
Keyword(s):  
Centrifugal Compressor ◽  
Gas Flow ◽  
Oil And Gas ◽  
Internal Flow ◽  
Oil And Gas Industry ◽  
Operating Conditions ◽  
Flow Coefficient ◽  
Low Flow ◽  
External Circuit ◽  
Flow Recirculation

A Centrifugal Compressor is a key component in the Oil and Gas Industry. It is used in all 3 areas of extraction, processing and transportation, namely, upstream, midstream and downstream. Generally a compressor’s life expectancy matches that of the wells it is used on. Barring retrofits and maintenance, a compressor can remain onsite for up to 20 years. However, at the end of the life of the well or in special conditions with perennial low flow rates, the reduced gas flow rate pushes the compressor to the left of its operating limit. At this point, the compressor surges. In order to bring it back to the normal operating conditions, flow is recirculated via an external circuit involving the anti-surge valve. This drops the flange to flange performance. A simpler method would be to recycle the flow internally, thus removing the losses from the external circuit. In this paper, internal flow recirculation is studied where flow is extracted from the stage diffuser and recycled back to the upstream return channel. This study was undertaken on a 2D impeller from the lowest flow coefficient stage of an OEM. Using 1D tools and detailed CFD methods to study this novel design, it is shown that the range can be shifted significantly.

Laminar secondary flows in curved rectangular ducts

1990 ◽  
Vol 217 ◽  
pp. 421-440 ◽  
Author(s):  
S. Thangam ◽  
N. Hur
Keyword(s):  
Aspect Ratio ◽  
Secondary Flow ◽  
Vortex Pair ◽  
Stability Diagram ◽  
Secondary Flows ◽  
Dean Number ◽  
Single Vortex ◽  
Curvature Ratio ◽  
Wide Range ◽  
Good Agreement

The occurrence of secondary flow in curved ducts due to the centrifugal forces can often significantly influence the flow rate. In the present work, the secondary flow of an incompressible viscous fluid in a curved duct is studied by using a finite-volume method. It is shown that as the Dean number is increased the secondary flow structure evolves into a double vortex pair for low-aspect-ratio ducts and roll cells for ducts of high aspect ratio. A stability diagram is obtained in the domain of curvature ratio and Reynolds number. It is found that for ducts of high curvature the onset of transition from single vortex pair to double vortex pair or roll cells depends on the Dean number and the curvature ratio, while for ducts of small curvature the onset can be characterized by the Dean number alone. A comparison with the available theoretical and experimental results indicates good agreement. A correlation for the friction factor as a function of the Dean number and aspect ratio is developed and is found to be in good agreement with the available experimental and computational results for a wide range of parameters.

Modelling and Simulation of Multiphase Flow Applicable to Processes in Oil and Gas Industry

2018 ◽  
Vol 14 (1) ◽  
Author(s):  
Florice Nzikou Mouketou ◽  
Andrei Kolesnikov
Keyword(s):  
Multiphase Flow ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Economic Loss ◽  
Secondary Flows ◽  
Solid Particles ◽  
Engine Oil ◽  
Oil Viscosity ◽  
Erosion Rates ◽  
Side Walls

Abstract Solid particle erosion is a mechanical process of destroying a wall surface material due to the impacts of solid particles entrained with a fluid. It is a frequent phenomenon encountered within various industries such as chemical processes, oil and gas, and hydraulic transportation. Erosion problem has led to enormous consequences such as oil spills caused by equipment failure of oil transmission pipelines, chokes valves, pipe fittings etc; resulting in considerable economic loss as well as safety and environmental concerns. In this study, a 3-D simulations are performed using CFD code ANSYS FLUENT to predict sand erosion rates under different engine-oil viscosity conditions for multiphase liquid, in a 90-degree standard (R/D = 1.5) elbow pipe. The CFD utilizes Eulerian-Lagrangian method to model the multiphase flow oil-water-sand in elbow. The realizable k-ε model is adopted for the fluid turbulence effects. The velocity and pressure distributions are analysed as contours for the fluid flow. In order to understand the dynamics of the erosion process, the motion of the solid particles are also investigated based on Stokes number as well as the effect of secondary flows. The results indicated that erosion rates decrease with the increase in oil viscosity. Additionally, erosion mainly occurs in two locations; at the extrados near the bend exit and also on the side walls of the downstream straight pipe. The unusual distribution of erosion on the side walls occurred as a result of the effect of secondary flows due to centrifugal force. The numerical results are in qualitative good agreement with the experimental data available in the literature for elbows in order to validate the presented modelling approach.

Maximum Drag Reduction Asymptote of Polymeric Fluid Flow in Coiled Tubing

2006 ◽  
Author(s):  
Subhash N. Shah ◽  
Yunxu Zhou
Keyword(s):  
Drag Reduction ◽  
Oil And Gas ◽  
Guar Gum ◽  
Oil And Gas Industry ◽  
Flow Loop ◽  
Polymeric Fluids ◽  
Curvature Ratio ◽  
Coiled Tubing ◽  
Industry Applications ◽  
Maximum Drag Reduction

This study experimentally investigates the drag reduction characteristics of the most commonly used polymer fluids in coiled tubing applications. The flow loop employed consists of 1/2-in. straight and coiled tubing sections. The curvature ratio (a/R where a and R are the radii of the tubing and the reel drum respectively) investigated is from 0.01 to 0.076 which covers the typical curvature ratio range encountered in the oil and gas industry applications. Fluids tested include xanthan gum, guar gum, and HPG (hydroxypropyl guar) at various polymer concentrations. It is found that the drag reduction in coiled tubing is significantly lower than that in straight tubing, probably due to the effect of secondary flow in curved geometry. The onset of drag reduction is also found to be delayed as the curvature ratio was increased. A correlation for the maximum drag reduction (MDR) asymptote in coiled tubing is developed. When the curvature ratio is set to zero, the new correlation reduces to the famous Virk's MDR asymptote for dilute polymer solutions in straight pipes. A new drag reduction envelope is also proposed for the analysis of drag reduction behavior of polymeric fluids in coiled tubing. Application of the new drag reduction envelope is also discussed.

Tracking Fluid Interface in Carbon Capture and Storage Cement Placement Application

2018 ◽  
Author(s):  
Ian Frigaard ◽  
Amir Maleki
Keyword(s):  
Carbon Capture ◽  
Oil And Gas ◽  
Tracer Particle ◽  
Carbon Capture And Storage ◽  
Main Idea ◽  
Laminar Flows ◽  
Secondary Flows ◽  
Two Fluids ◽  
Primary Cementing ◽  
And Storage

One current methodology for Carbon Capture and Storage (CCS) involves pumping carbon dioxide (CO2) into a depleted oil and gas reservoir, usually via an existing well. Permanence of the storage in this case relies on the integrity of the reservoir and also the avoidance of leakage at the points of entry. Two different cementing procedures are involved in the latter problem: primary cementing and squeeze cementing. Here we consider how to track the interface between two fluids during primary cementing. The main idea is to exploit the density difference between successive fluids pumped in order to design a tracer particle to sit at the interface. Although apparently trivial, such particles must also overcome strong secondary flows in order to remain in the interface. We provide a proof of concept analysis of this situation assuming the displacement involves laminar flows of two Newtonian fluids in a narrow vertical annulus and demonstrate its feasibility.

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