Flow In Horizontal Pipe Research Articles

A Simplified Calibration of Liquid Hold-Up and Film Thickness in Annular Flow in Horizontal Pipe

Annular flow is majorly encountered in petroleum industry, where gas and liquid are conveyed from gas wells or oil wells (dominated by gas) to the surface through the transport lines. A simplified annular flow bench calibration for liquid hold-up and film thickness in horizontal pipe was conducted using water/air in a 2-inch (50mm) Plexiglas pipe test tube with a length of 154mm. The calibration was achieved using five different acryl plastic rods inserts of 49mm, 48mm, 47mm, 46mm and 45mm with a length of 153mm respectively. The 2-inch (50mm) plexiglass test tube was installed with two pairs of conductivity ring sensors for liquid hold-up and the flush-mounted conductance probe sensor for liquid film thickness. The acts of measuring, recording and transmitting the data to a usable state were achieved using a digital data acquistion system (Labview). The conductivity ring sensors C1 and C2 results which were for the liquid hold-up in the calibration gave R-factors of 0.9962 and 0.9947 respectively, while the conductance probe sensor for the liquid film thickness presented an R-factor of 0.9949.

Numerical solution for magnetohydrodynamic flow in straight horizontal elliptical pipe

Numerical solution for magnetohydrodynamic flow in straight horizontal elliptical pipe

Velocity profile for magnetohydrodynamic flow in straight horizontal elliptical pipe

Velocity profile for magnetohydrodynamic flow in straight horizontal elliptical pipe

Temperature distribution for magnetohydrodynamic flow in straight horizontal elliptical pipe

Temperature distribution for magnetohydrodynamic flow in straight horizontal elliptical pipe

Pressure Signal Analysis for the Characterization of High-Viscosity Two-Phase Flows in Horizontal Pipes

We study a high-viscosity two-phase flow through an analysis of the corresponding pressure signals. In particular, we investigate the flow of a glycerin–air mixture moving through a horizontal pipeline with a U-section installed midway along the pipe. Different combinations of liquid and air mass flow rates are experimentally tested. Then, we examine the moments of the statistical distributions obtained from the resulting pressure time series, in order to highlight the significant dynamical traits of the flow. Finally, we propose a novel correlation with two dimensionless parameters: the Euler number and a mass-flow-rate ratio to predict the pressure gradient in high-viscosity two-phase flow. Distinctive variations of the pressure gradients are observed in each section of the pipeline, which suggest that the local flow dynamics must not be disregarded in favor of global considerations.

Slug Regime Transitions in a Two-Phase Flow in Horizontal Round Pipe. CFD Simulations

The main objective of the study is to propose a technical solution integrated into the pipeline for the transition of the flow regime from slug to bubbly two-phase flow. The object of research is isothermal two-phase gas–Newtonian-liquid flow in a horizontal circular pipeline. There is local resistance in the pipe in the form of a streamlined transverse mesh partition. The mesh partition ensures the transition of the flow from the slug regime to the bubbly regime. The purpose of the study is to propose a technical solution integrated into the pipeline for changing the flow regime of a two-phase flow from slug to bubbly flow. The method of research is a simulation using computational fluid dynamics (CFD) numerical simulation. The Navier–Stokes equations averaged by Reynolds describes the fluid motion. The k-ε models were used to close the Reynolds-averaged Navier–Stokes (RANS) equations. The computing cluster «Polytechnic—RSK Tornado» was used to solve the tasks. The results of simulation show that pressure drop on the grid did not exceed 10% of the pressure drop along the length of the pipeline. The mesh partition transits the flow regime from slug to layered one, which will help to increase the service life and operational safety of a real pipeline at insignificant energy costs to overcome the additional resistance integrated into the pipeline.

Investigation of the Flow Pattern Transition Behaviors of Viscous Oil–Water Flow in Horizontal Pipes

In the petroleum industry, oil–water flow appears in pipelines when connate water or injected water is present in the reservoir. As the characteristics of flow patterns differ, studying their trans...

Numerical study of thermal mixing mechanisms in T-junctions

This paper presents wall-resolved Large-Eddy Simulations (LES) of thermal mixing mechanisms both in horizontal and vertical T-junctions. The mass flow rate ratio (ṁm/ṁb) of the mixing fluids is 3 and the temperature difference (Tm-Tb) is 180 K. The numerical results are validated with experimental data from the horizontal T-junction (warm horizontal main pipe flow and a cold branch pipe flow coming from the side) from Zhou et al. [32] and with yet unpublished measurement data of the vertical T-junction (warm horizontal main pipe flow and a cold branch pipe flow coming from above) of the Fluid-Structure Interaction (FSI) facility. In particular, we study the influence of the inflowing cold water stream in various T-junction configurations on the mixing mechanism. Additionally, this paper also contains a close investigation of temperature fluctuations in the mixing zone and a spectral analysis of the fluid temperature signal at chosen positions close to the piping material. On the whole, the predicted LES results are generally in good agreement with the corresponding experimental data for both configurations. Conforming to our simulations, a stable stratification in the horizontal configuration may be transformed into an unstable stratified flow behavior in the vertical configuration, that enhances the thermal mixing and heat transfer.

Experimental investigation and new void-fraction calculation method for gas–liquid two-phase flows in vertical downward pipe

The void fraction is a key parameter of the two-phase flow in vertical downward pipes, particularly for calculating the mixture density, mixture velocity, mixture viscosity, heat transfer coefficient, and pressure gradient of the flow. Studies on two-phase flows have focused primarily on vertical upward and horizontal pipe flows, while vertical downward pipe flows have been largely neglected. Compared with the flow characteristics of the gas–liquid two-phase flow in upward pipes, those of a downward pipe flow are more complex under the interaction of the gravity, buoyancy, and inertial forces. In this study, a detailed experimental analysis of the void fraction of the gas–liquid two-phase flow in a vertical downward pipe was conducted with a pipe having an inner diameter of 20 mm. A total of 171 void-fraction data points were measured using the quick-closing valve method, and the performances of 12 commonly used correlations that do not take into consideration the flow pattern were assessed based on experimental data points. Errors were obtained on using some of the correlations for calculating the void fraction of the gas–liquid two-phase.flow in a vertical downward pipe at a low liquid superficial velocity. These models will regularly produce errors in the calculation of the void fraction, mainly because this problem is outside the scope of their application. In addition, a new model that takes into consideration the flow pattern was established based on the drift flux model; this new model overcomes the deficiencies of the conventional correlations in the calculation of the void fraction of the gas–liquid two-phase flow in vertical downward pipes at a low liquid superficial velocity. The reliability of the new method and 12 conventional correlations was assessed using 243 published data points. The mean relative errors of these correlations ranged from −21.65% to 8.65%, and the average absolute errors ranged from 8.57% to 23.17%. The results of the proposed method fit the experimental data in the literature better than those of the 12 existing correlations; the average relative error was −2.80%, and the average absolute error was 6.49%. The proposed model thus improves the prediction of void fractions of the gas–liquid two-phase flow in downward pipes.

Numerical analysis of dilute gas-solid flows in a horizontal pipe and a 90° bend coupled with a newly developed drag model

The influence of particle concentration on the drag force of a particle deserves attention when using the Lagrangian Particle Tracking methods for the prediction of industrial type gas-solid flows. The Lagrangian approach is best suited to applications where the solids volume fraction is low, and the effect of particle concentration can be ignored. In the present work, a 3D time dependent numerical analysis is performed to study the effect of Lagrangian model improvements to replicate experimental studies of straight horizontal pipe flow and flow through a 90° horizontal-to-vertical bend. The present predictions are compared with published experimental data of Tsuji and Morikawa (1982), and Yilmaz (1997). Special attention is paid to influence of particle mass-flow rates and conveying velocity on the particle motion within the system. This study used a CFX-4 package, where the ability to modify the code was necessary to include particle model improvements. These improvements included implementing a newly drag force model developed as a part of this research work. Particle-wall collision and particle-particle collision models developed by Sommerfeld (1992), and Sommerfeld (2001) are also implemented in the CFD model. The standard k–ε dispersed turbulence model was utilized as the predictions for the gas phase only gave similar predicted axial velocity compared to the more computationally demanding Reynolds stress model. The results showed that the inclusion of the various improvements lead to reasonable predicted particle velocities in both the upper and lower regions of the straight horizontal pipe which denote the dilute and dense regions respectively. It was also found that the inclusion of the rough-wall particle wall collision model decreases the axial particle velocity in the lower region where the bulk of the particle wall collisions occur. While the inclusion of the particle collision models tends to disperse the particles away from the lower region resulting in a less dense lower section and a distinctly more homogenous particle distribution compared with the standard model predictions. Further, the increase in particle concentration leads to a reduction in axial velocity due to a loss of momentum through particle-wall and particle-particle collisions. Finally, the improved CFD model best predicted both the reduction and increase in the particle velocities in the different regions.

Statistical characterization of horizontal slug flow using snapshot proper orthogonal decomposition

Slug flow is an intermittent and complex gas-liquid flow pattern, that can cause severe problems in industrial operations and lead to large uncertainties in multiphase flow metering. These problems are primarily caused by the liquid slugs of the flow. In this context, different cases of slug flow in horizontal pipes are investigated to find a statistical characterization of the slugs in time and space. To achieve this, snapshot proper orthogonal decomposition (snapshot POD) with an additional mode coupling algorithm is employed, which provides an energy-ranked mode basis of the underlying coherent structures. It is shown that the characterization for the considered slug flows can be derived from the temporal and spatial information of the dominant mode pair. In that regard, the slug frequencies, the averaged slug body length and an energy representation of the slugs are obtained from this method. Furthermore, the accuracy of this characterization is shown and the influence of the size of the observed pipe section on its reliability is investigated.

Uncertainty of isokinetic sampling of the phase composition of a gas-oil-water mixture at different regimes of a developed horizontal pipe flow

The paper presents ten well-known developed stable flow regimes of an air/water/oil mixture in a horizontal pipe simulated numerically. The results have been tested by comparing the obtained fields of phase distribution and velocity with the results of experimental observations published in the literature. For sampling, four classical designs of isokinetic sampling probes guided by the existing standards for two-phase flows have been considered. The obtained results showed that the reliability of the estimation of the phase composition in the three-phase mixture by isokinetic sampling probes strongly depends on the flow regime. Therefore, in real oil production conditions with the presence of unstable and transient regimes, using the isokinetic probes without preliminary preparation of the flow in front of the sampling section is not recommended.

CFD investigation of the flow characteristics of liquid–solid slurry in a large-diameter horizontal pipe

As an efficient and environmentally friendly method of delivering solid particles, the transport of liquid–solid slurry through a pipeline has attracted considerable attention. However, the flow characteristics of the slurry in large-diameter pipes, especially multi-sized slurry, are far from fully understood. In this study, an Eulerian multiphase model is applied to investigate single- and multi-sized slurry flows in horizontal pipes. The results show that the pipe diameter has a distinct effect on the particle distribution and that the flow properties of multi-sized slurry are different from those of single-sized slurry. In the 900-mm pipe, the variations in the solid concentration and velocity distributions of single-sized slurry are significantly affected by the particle size and efflux concentration but display weak dependence on the mixture velocity. The total particle concentration profile of the multi-sized slurry becomes relatively symmetric in the upper half of the pipe and highly asymmetric in the lower half with increasing mean particle size. The pressure drop per meter of the single-sized slurry first decreases and then increases with increasing particle size, and the pressure drop of the multi-sized slurry containing coarse particles is much higher than that of the single-sized slurry under the same working conditions.

Estimation of Pressure Drop of Two-Phase Flow in Horizontal Long Pipes Using Artificial Neural Networks

Abstract Gas–liquid two-phase flows through long pipelines are one of the most common cases found in chemical, oil, and gas industries. In contrast to the gas/Newtonian liquid systems, the pressure drop has rarely been investigated for two-phase gas/non-Newtonian liquid systems in pipe flows. In this regard, an artificial neural networks (ANNs) model is presented by employing a large number of experimental data to predict the pressure drop for a wide range of operating conditions, pipe diameters, and fluid characteristics. Utilizing a multiple-layer perceptron neural network (MLPNN) model, the predicted pressure drop is in a good agreement with the experimental results. In most cases, the deviation of the predicted pressure drop from the experimental data does not exceed 5%. It is observed that the MLPNN provides more accurate results for horizontal pipelines in comparison with other empirical correlations that are commonly used in industrial applications.

Experimental study on gas-liquid-liquid three-phase flow patterns and the resultant pressure drop in a horizontal pipe upstream of the 90° bend

The use of 90˚ bend for diversion of flow in different orientations is widespread. The current study is focused on the effect of 90˚ bend on gas-oil–water three-phase flow in an upstream horizontal pipe. The diameter of the test section is 0.1524 m, and (R/d) ratio of the bend is 1. The ranges of superficial velocities of gas, oil, and water were 0.5–5, 0.08–0.36, and 0.08–0.36 m/s, respectively. The observed gas–liquid flow patterns are slug, pseudo-slug, stratified wavy, stratified roll wave, and stratified flow. The oil and water were observed to be flowing as a separate, partially mixed, and fully mixed liquid. Flow regime maps have been plotted to analyze the transition of flow patterns. The variation in pressure drop with the flow patterns has been studied. The experimental data has been used to develop pressure drop prediction correlation and the comparison with experimental results showed good agreement.

Investigation of the Effect of Fluids Superficial Velocity on Initiation and Development of Slug Flow in a Horizontal Hydraulics Pipe

The aim of this study is to investigate the effect of fluids superficial velocity on the characteristics of two-phase slug flow in a horizontal hydraulics pipe covering slug flow initiation and development. Air and water were employed as the working fluids. Slug flow characteristics were visually observed at 25D and 200D in a 19 mm internal diameter of acrylic pipe for the initiation and fully developed slug flow conditions, respectively. Flow visualization was taken using high speed video cameras at 400 fps and then analyzed using image processing method. Based on the flow pattern characteristics, several slug flow initiation mechanisms were obtained. Under the investigated conditions, at low to medium air superficial velocity (JG) with low to high water superficial velocity (JL), slug flow initiation mechanisms consisted of wave growth, hydraulic jump, blockage, and slug decaying. While wave initiation, wave formation, disturbance, wave coalescence, and incompletely developed slug mechanisms were observed at medium to high JG with low to high JL. After slug flow was fully developed, it was found that the higher the water superficial velocity resulted in lower void fraction and higher slug frequency. In the meantime, pressure drop and liquid slug velocity increased considerably with the increase of both JG and JL. Maximum pressure drop of 8.35 kPa/m occurred at JL of 2.00 m/s and JG of 3.76 m/s. The highest slug frequency of 6.67 1/s was observed at JL of 2.00 m/s and JG of 2.12 m/s. This information is important for designing fluid flow in horizontal hydraulics pipes and for consideration in predicting the development of the slug flow in order to avoid the negative impact of slug flow in industrial applications.

Experimental study on the effect of diameter on gas–liquid CCFL characteristics of horizontal circular pipes

The gas–liquid two-phase countercurrent flow in horizontal pipes is closely related to the safe operation of marine diesel engines with underwater exhausts, and nuclear power plants with pressurized water reactors. A visualization experiment on the effect of the diameter size on the counter current flow limitation (CCFL) characteristics of horizontal pipes was performed in the diameter range of 20–130 mm using air and water as the two phases. The results indicate that with a certain gas flow rate, the flow rate of the backflow liquid significantly increases with increasing diameter. Wallis models and those using the Froude–Ohnesorge numbers can correlate the effect of the change in diameter size when the diameters are greater than 100 mm, whereas they lose normalization capability with diameters less than 100 mm. From an analysis of the physical mechanism of formation of this diameter effect, a novel correlation model based on a new dimensionless group for each phase, consisting of the dimensionless inertia and dimensionless viscous force, was proposed for predicting the CCFL characteristics of small diameter pipes. Meanwhile, another correlation based on the Wallis model was also advanced for predicting the CCFL characteristics of large diameter pipes.

An improved semi-empirical friction model for gas-liquid two-phase flow in horizontal and near horizontal pipes

ABSTRACT Pressure drop and liquid hold-up are two very important fluid flow parameters in design and control of multiphase flow pipelines. Friction factors play an important role in the accurate calculation of pressure drop. Various empirical and semi-empirical closure relations exist in the literature to calculate the liquid-wall, gas-wall and interfacial friction in two-phase pipe flow. However most of them are empirical correlations found under special experimental conditions. In this paper by modification of a friction model available in the literature, an improved semi-empirical model is proposed. The proposed model is incorporated in the two-fluid correlations under equilibrium conditions and solved. Pressure gradient and velocity profiles are validated against experimental data. Using the improved model, the pressure gradient deviation from experiments diminishes by about 3%; the no-slip condition at the interface is satisfied and the velocity profile is predicted in better agreement with the experimental data.

Numerical simulation, validation, and analysis of two-phase slug flow in large horizontal pipes

Multiphase flow, especially two-phase gas-liquid flow, is of great importance for a variety of applications and industrial processes, for example in the nuclear, chemical, or oil and gas industries. In this contribution, we present simulation results for gas-liquid slug flow in large horizontal pipes. Six test cases with different oil, water, and gas flow rates are considered, which cover a wide range of different slug flows. The numerical predictions are validated by comparison with experimental data obtained from video observations. The relative error of the mean liquid level between experiment and simulation is less than 12.3% for all but one test cases. Furthermore, a frequency analysis is performed. The single-sided amplitude spectrum as well as the smoothed power spectral density are calculated. For both, experimental and simulation data, one observes an increase of the dominant frequencies if the ratio of liquid and gas superficial velocity is increased.

Experimental and Theoretical Study of Interface Characteristics of Gas–Liquid Stratified Flow in Horizontal Pipe at High Pressure

Wave stratified flow is widely encountered in processing industry, the interface wave impacts heat and mass transfer between the fluids, and flow pattern transition from it to slug flow makes it difficult to deal with the processing fluids that transported by long pipelines especially. Meanwhile, the interface wave influences the viscous drag forces working on the fluids in the pipe, which is impacted by the characteristics of interface profile, such as wave length, amplitude and propagation speed. Experiment of air–water two-phase flow in horizontal pipe at different pressures (0.1 MPa, 2 MPa) are carried out, the influence of pressure on interface profile characteristics is studied, new models for wave length, amplitude, frequency and propagation speed are proposed and tested, and good performance is proved. Shear stress working on interface wave is theoretically calculated, influence of both fluids superficial velocities and pressure on it are studied, and its influence on wave propagation speed is formulated.