scholarly journals Effects of a new drag reduction agent on natural gas pipeline transportation

2019 ◽  
Vol 11 (10) ◽  
pp. 168781401988192
Author(s):  
Yachao Ma ◽  
Zhiqiang Huang ◽  
Zhanghua Lian ◽  
Weichun Chang ◽  
Huan Tan
Keyword(s):  
Natural Gas ◽  
Drag Reduction ◽  
Gas Flow ◽  
Reduction Rate ◽  
Field Tests ◽  
Wall Region ◽  
Pipeline Transportation ◽  
Frictional Drag ◽  
Inner Surface ◽  
Near Wall

Pipeline transportation is the major way to transport natural gas. How to reduce energy dissipation and retain the gas delivery capacity are the main problems of pipeline transportation. In this article, a new drag reduction agent named CPA is synthesized. An experimental investigation on the roughness-reducing effect of CPA on the inner surface of the pipeline is carried out. The effect of CPA on natural gas flow regime in the near-wall region of the pipeline is researched with Fluent software. Field tests for calculating the drag reduction rate of CPA are performed. The results show that CPA can reduce the roughness of the inner surface effectively, and the maximum roughness-reducing percentage is 38.74%. Meanwhile, CPA can reduce the frictional drag and thereby improve transportation capacity of pipelines. After injecting CPA, the streamline of the natural gas in the near-wall region is more consistent. The velocity fluctuation decreases by 93.2%. The mean turbulence intensity decreases by 53.01%. The pipeline pressure further decreases the roughness of the inner surface of the pipeline. The field test shows that the maximum drag reduction rate of CPA is 25%, and it is suitable for application in gathering and transportation pipelines of high flow velocity and turbulent rough region.

Experimental Research on the Drag Reduction Technology of Nature Gas Pipeline Transportation

2011 ◽  
Vol 361-363 ◽  
pp. 982-989 ◽  
Author(s):  
Zhi Qiang Huang ◽  
Rong Gai Zhu ◽  
Zhen Chen ◽  
Xue Yuan Li ◽  
Shuang Jing ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Natural Gas ◽  
Drag Reduction ◽  
Flow Pattern ◽  
Flow Resistance ◽  
Gas Pipeline ◽  
Wall Region ◽  
Low Carbon ◽  
Pipeline Transportation ◽  
Inner Surface

As an efficient and environment-friendly energy, natural gas has become an inevitable choice for improving environment, achieving the low carbon economy and the sustainable development all around world. However, flow resistance produced in the course of the gas pipeline transportation caused large loss of transportation energy and brought down the transportation capacity. Therefore, this paper have developed a deep researches on the interaction mechanism between a drag reduction agent (DRA) and the inner surface of natural gas pipeline, the flow pattern improvement regularity about DRA membrane acting on the near-wall region of the pipeline, the relation between the flow pattern improvement and friction resistance, the effect regularity of DRA on the friction coefficient of the pipeline inner surface, and the relation between the alternation of the friction coefficient and the drag reduction. According to all above studies, the fundamental reason for flow resistance of the gas transportation has been found, and the drag reduction mechanism of the gas pipeline transportation has also been hold of. Field test shows that the application of the DRA in the course of the gas pipeline transportation reduced the friction loss by 12%-16.5%, and raised the transfer efficiency by 8%-12%.

Simultaneous PIV and PLIF Measurement on the Drag Reducing Channel Flow of the Homogeneous Surfactant Solution

2011 ◽  
Author(s):  
Takahiro Watanabe ◽  
Kohei Tanaka ◽  
Masaaki Motozawa ◽  
Yasuo Kawaguchi
Keyword(s):  
Drag Reduction ◽  
Reduction Rate ◽  
Surfactant Solution ◽  
Coherent Motion ◽  
Wall Region ◽  
Frictional Drag ◽  
Piv Measurement ◽  
Planar Laser ◽  
The Relationship ◽  
Plif Measurement

Simultaneous Particle Image Velocimetry (PIV) measurement and Planar Laser Induced Fluorescence (PLIF) measurement at the same position were performed to clarify the relationship between spatial structure and mass transfer in the drag reducing surfactant flow. In the drag reducing flow, mass flux is largely suppressed in the near-wall region with increasing drag reduction rate. To discuss the relationship between coherent motion and drag reduction more detail, weighted probability density function was also calculated. As a result of simultaneous measurement, diffusion of wall-normal direction is largely suppressed and this indicated that turbulent coherent structure changes and sweep and ejection which produce the skin frictional drag are suppressed.

Effects of Spatial Resolution and Box Size on Numerical Solutions of Turbulent Flows

2005 ◽  
Author(s):  
Dongmei Zhou ◽  
Kenneth S. Ball
Keyword(s):  
Drag Reduction ◽  
Channel Flow ◽  
Spatial Resolution ◽  
Numerical Solutions ◽  
Velocity Profiles ◽  
Wall Region ◽  
Computational Domain ◽  
Mean Velocity ◽  
Significant Difference ◽  
Near Wall

This paper has two objectives, (1) to examine the effects of spatial resolution, (2) to examine the effects of computational box size, upon turbulence statistics and the amount of drag reduction with and without the control scheme of wall oscillation. Direct numerical simulation (DNS) of the fully developed turbulent channel flow was performed at Reynolds number of 200 based on the wall-shear velocity and the channel half-width by using spectral methods. For the first objective, four different grids were applied to the same computational domain and the biggest impact was observed on the logarithmic law of mean velocity profiles and on the amount of drag reduction with 28.3% for the coarsest mesh and 35.4% for the finest mesh. Other turbulence features such as RMS velocity fluctuations, RMS vorticity fluctuations, and bursting events were either overpredicted or underpredicted through coarse grids. For the second objective, two different minimal channels and one natural full channel were studied and 3% drag reduction difference was observed between the smallest minimal channel of 39.1% and the natural full channel of 36.2%. In the near-wall region, however, the minimal channel flow did not exhibit significant difference in the mean velocity profiles and other lower-order statistics. Finally, from this systematical study, it showed that the accuracy of DNS depends more on the spanwise resolution, and it also confirmed that a minimal channel model is able to catch key structures of turbulence in the near-wall region but is much less expensive.

Study of gaseous velocity slip in nano-channel using molecular dynamics simulation

2014 ◽  
Vol 24 (6) ◽  
pp. 1338-1347 ◽  
Author(s):  
Fubing Bao ◽  
Zhihong Mao ◽  
Limin Qiu
Keyword(s):  
Molecular Dynamics ◽  
Gas Flow ◽  
Interaction Strength ◽  
Flow Characteristics ◽  
Velocity Slip ◽  
Dynamics Simulation ◽  
Wall Region ◽  
Content Type ◽  
Slip Phenomenon ◽  
Near Wall

Purpose – The purpose of this paper is to investigate the gas flow characteristics in near wall region and the velocity slip phenomenon on the wall in nano-channels based on the molecular dynamics simulation. Design/methodology/approach – An external gravity force was employed to drive the flow. The density and velocity profiles across the channel, and the velocity slip on the wall were studied, considering different gas temperatures and gas-solid interaction strengths. Findings – The simulation results demonstrate that a single layer of gas molecules is adsorbed on wall surface. The density of adsorption layer increases with the decrease of gas temperature and with increase of interaction strength. The near wall region extents several molecular diameters away from the wall. The density profile is flatter at higher temperature and the velocity profile has the traditional parabolic shape. The velocity slip on the wall increases with the increase of temperature and with decrease of interaction strength linearly. The average velocity decreases with the increase of gas-solid interaction strength. Originality/value – This research presents gas flow characteristics in near wall region and the velocity slip phenomenon on the wall in nano-channels. Some interesting results in nano-scale channels are obtained.

Turbulent drag reduction in plane Couette flow with polymer additives: a direct numerical simulation study

2018 ◽  
Vol 846 ◽  
pp. 482-507 ◽  
Author(s):  
Hao Teng ◽  
Nansheng Liu ◽  
Xiyun Lu ◽  
Bamin Khomami
Keyword(s):  
Numerical Simulation ◽  
Drag Reduction ◽  
Large Scale ◽  
Core Region ◽  
Wall Region ◽  
Plane Couette Flow ◽  
The Core ◽  
Elastic Potential Energy ◽  
Conformation Tensor ◽  
Near Wall

Drag reduction (DR) in plane Couette flow (PCF) induced by the addition of flexible polymers has been studied via direct numerical simulation (DNS). The similarities and differences in the drag reduction features of PCF and plane Poiseuille flow (PPF) have been examined in detail, particularly in regard to the polymer-induced modification of large-scale structures (LSSs) in the near-wall turbulence. Specifically, it has been demonstrated that in the near-wall region, drag-reduced PCF has features similar to those of drag-reduced PPF; however, in the core region, intriguing differences are found between these two drag-reduced shear flows. Chief among these differences is the significant polymer stretch that arises from the enhanced exchanges between elastic potential energy and turbulent kinetic energy and the commensurate observation of peak values of the conformation tensor components $\unicode[STIX]{x1D60A}_{yy}$ and $\unicode[STIX]{x1D60A}_{zz}$ in this region. This finding is in stark contrast to that of drag-reduced PPF where the polymer stretch and the exchanges between elastic potential energy and turbulent kinetic energy in the core region are insignificant; to this end, in drag-reduced PPF, peak values of the conformation tensor components appear in the near-wall region. Therefore, this study paves the way for understanding the underlying flow physics in drag-reduced PCF, particularly in the context of elastic theory. Moreover, the longitudinal large-scale streaks at the channel centre of drag-reduced PCF are greatly strengthened due to the increased production/dissipation ratio; the LSS imprint effects on the near-wall flow of drag-reduced PCF monotonically increase as the Weissenberg number is enhanced.

Evaluation of Drag Reduction Agent Used in Oil Pipeline Transportation

2012 ◽  
Vol 217-219 ◽  
pp. 153-156 ◽  
Author(s):  
Zhi Wu He ◽  
Ning Jun Li ◽  
Zhen Yun Zhang ◽  
Hui Li Yang ◽  
Ai Jun Wei
Keyword(s):  
Drag Reduction ◽  
Reduction Rate ◽  
Pipeline Transportation ◽  
Oil Pipeline ◽  
Test Loop ◽  
Increase Rate

This article describes the principles and methods of evaluating DRA in the lab, then evaluate the effect of DRA in the lab by designing a DRA test loop. This is measure that thoes DRA difference concentration be provided with flow increase rate and Drag reduction rate in test loop.

Experimental and Numerical Study of Bubble Drag Reduction on a Flat Plate

2017 ◽  
Author(s):  
ShiJie Qin ◽  
DaZhuan Wu
Keyword(s):  
Drag Reduction ◽  
Flat Plate ◽  
Experimental Results ◽  
Air Injection ◽  
Wall Region ◽  
Buffer Region ◽  
Wide Range ◽  
Flow Speeds ◽  
Near Wall ◽  
Injection Rates

The presence of near wall bubbles may reduce the skin friction drag. This phenomenon has been studied by well designed experiments and combined computational fluid dynamics (CFD) and population balance model (PBM) simulations in this paper. Drag reductions and bubble distributions over a flat plate have been implemented in cavitation tunnel experiments at various flow speeds and air injection rates. CFD-PBM modeling for bubble drag reduction (BDR) has been modified and validated by the flat plate experiments. Drag and lift forces are fully modeled, and bubble breakup and coalescence are calculated. A wide range of bubble sizes are well captured base on the aforementioned numerical consideration. And this modeling work can be further used to design full-scale BDR ships and to discover detailed BDR mechanisms. The predicted drag reductions and bubble distributions are in reasonable accordance with the experimental results. Approximately 30% of BDR is achieved both in the numerical and experimental results. The influence of flow speeds and air injection rates on drag reductions and bubble distributions is discussed. In particular, the mechanism of BDR is analyzed based on the detailed flow filed profiles from numerical simulations. Higher air injection rates generally lead to thicker bubble layer thickness from the rear-part of buffer region (20 < y+ < 30) to turbulent region (y+ > 30). And noticeable increases of air volume fraction in the laminar region (y+ < 5) and forepart of buffer region (5 < y+ < 20). The change of the velocity gradient in the near wall region is considered to be directly related to drag reduction.

scholarly journals Large eddy simulation of near-wall turbulent flow over streamlined riblet-structured surface for drag reduction in a rectangular channel

2020 ◽  
Vol 24 (5 Part A) ◽  
pp. 2793-2808
Author(s):  
Hussain Al-Kayiem ◽  
Desmond Lim ◽  
Jundika Kurnia
Keyword(s):  
Large Eddy Simulation ◽  
Turbulent Flow ◽  
Drag Reduction ◽  
Rectangular Channel ◽  
Wall Region ◽  
Mean Velocity ◽  
Structured Surface ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Near Wall

Sharkskin-inspired riblets are widely adopted as a passive method for drag reduc?tion of flow over surfaces. In this research, large eddy simulation of turbulent flow over riblet-structured surface in a rectangular channel domain were performed at various Reynolds numbers, ranging from 4200-10000, to probe the resultant drag change, compared to smooth surface. The changes of mean streamwise velocity gradient in wall-normal direction at varied locations around riblet structures were also investigated to reduce mechanisms of streamlined riblet in reducing drag. The computational model is validated by comparing the simulation results against analytical and experimental data, for both smooth and riblet surfaces. Results in?dicating that the performance of the proposed streamlined riblet shows 7% drag reduction, as maximum, which is higher than the performance of L-shaped riblet with higher wetted surface area. The mean velocity profile analysis indicates that the streamlined riblet structures help to reduce longitudinal averaged velocity component rate in the normal to surface direction of near-wall region which leads to laminarization process as fluid-flows over riblet structures.

Parametric Study of Viscoelastic Turbulence Within an Obstructed Channel Flow

2011 ◽  
Author(s):  
Tomohiro Kawase ◽  
Takahiro Tsukahara ◽  
Yasuo Kawaguchi
Keyword(s):  
Drag Reduction ◽  
Reduction Rate ◽  
Weissenberg Number ◽  
Viscoelastic Flow ◽  
Viscoelastic Flows ◽  
Streamwise Vortices ◽  
Newtonian Flow ◽  
Frictional Drag ◽  
Parametric Dependence ◽  
Obstructed Channel Flow

The behavior of viscoelastic flow behind a two-dimensional slits was examined using direct numerical simulations (DNS). We performed DNS at five different conditions with changing the Reynolds number and the Weissenberg number, to investigate the parametric dependence of several characters of the viscoelastic flows (e.g., Toms effect and Barus effect) accompanied by the separation and reattachment. In the present conditions, the drag reduction rate was achieved from 15.1% to 19.7%. It was found that the wall-normal viscoelastic stress mainly enhanced the Barus effect in the present geometry and the streamwise viscoelastic force caused an increase of the drag. We found that, at a Weissenberg number higher than a certain level, the drag reduction rate should be decreased despite the reduced turbulent frictional drag. Moreover, we observed that, in the Newtonian flow, the spanwise vortices were dominant in a downstream region of the slits, while the streamwise vortices were dominant there in the case of the viscoelastic flow.

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