Numerical Study of Pipeline-Riser Slugging in an Open Source Way

2016 ◽  
Author(s):  
Xiangyin Meng ◽  
Longbin Tao
Keyword(s):  
Open Source ◽  
Mesh Generation ◽  
Pressure Fluctuation ◽  
Numerical Study ◽  
Internal Flow ◽  
Post Process ◽  
System Pressure ◽  
Fluid Properties ◽  
Gas Liquid Flow ◽  
First Time

This paper describes an open source numerical investigation into slugging flow in a typical two-dimensional pipeline-riser for the first time. CFD tools Gmsh, OpenFOAM and ParaView are employed for mesh generation, numerical simulation and post process respectively. Original OpenFOAM solver ‘twoPhaseEulerFoam’ is used to simulate the gas-liquid flow in the system consisting of inclined pipeline and vertical riser. By comparing the numerical results of slugging phenomena and pressure fluctuation periods to previous experimental observations, it can be confirmed that it is possible to carry out such simulations in a complete open source way. Based on case studies, pressure fluctuation features in a typical single slugging cycle is also discussed in details. Furthermore, temperature variation of the internal flow due to air compressibility is found to have similar fluctuation period as that of pressure. In the end, the impacts of fluid properties on system pressure variations are discussed too. To future numerical investigations of subsea pipeline-riser induced slugging, present work is a basis for further open source solvers development.

An Experimental and Numerical Study of Regulating Performance and Flow Loss in a V-Port Ball Valve

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Junyu Tao ◽  
Zhe Lin ◽  
Chuanjing Ma ◽  
Jiahui Ye ◽  
Zuchao Zhu ◽  
...  
Keyword(s):  
Pressure Fluctuation ◽  
Fluid Transport ◽  
Numerical Study ◽  
Internal Flow ◽  
External Pressure ◽  
Ball Valve ◽  
Flow Coefficient ◽  
Design And Optimization ◽  
Stable Position ◽  
Valve Opening

Abstract Process valves are responsible for regulating and controlling the rate and direction of flow in pipeline systems. The V-port ball valve is one kind of process valve with a regulating performance influenced by V-angle. In this article, a DN50 V-port ball valve is taken as the research object. This work therefore aims to investigate the effect of and relationship between the V-angle on valve performance and internal flow properties via experiments and numerical simulations. Results indicate that an increase in either V-angle or valve opening causes a large-pressure fluctuation near the valve outlet, thus leading to a long pressure-stable distance. Meanwhile, the flow coefficient increases exponentially with valve opening, and the value of the exponent remains at 2.5 for different V-angles. Furthermore, the stable position of internal energy loss along the downstream pipe is well-matched with the stable position of external pressure fluctuation. This inspires a new method for controlling the pressure stability downstream from the valve. These results may facilitate improvements in the design and optimization of the process valve, thus benefiting the development of fluid transport techniques in energy industries.

scholarly journals Numerical Study of the Behaviors of Ventilated Supercavities in a Periodic Gust Flow

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Renfang Huang ◽  
Siyao Shao ◽  
Roger E. A. Arndt ◽  
Xianwu Luo ◽  
Yiwei Wang ◽  
...  
Keyword(s):  
Internal Pressure ◽  
Pressure Fluctuation ◽  
Cavity Length ◽  
Numerical Study ◽  
Maximum Amplitude ◽  
Internal Flow ◽  
External Pressure ◽  
Incoming Flow ◽  
Flow Perturbation ◽  
Number Variation

Abstract We conducted a numerical simulation of ventilated supercavitation from a forward-facing cavitator in unsteady flows generated by a gust generator under different gust angles of attack and gust frequencies. The numerical method is validated through the experimental results under specific steady and unsteady conditions. It is shown that the simulation can capture the degree of cavity shape fluctuation and internal pressure variation in a gust cycle. Specifically, the cavity centerline shows periodic wavelike undulation with a maximum amplitude matching that of the incoming flow perturbation. The cavity internal pressure also fluctuates periodically, causing the corresponding change of difference between internal and external pressure across the closure that leads to the closure mode change in a gust cycle. In addition, the simulation captures the variation of cavity internal flow, particularly the development internal flow boundary layer along the cavitator mounting strut, upon the incoming flow perturbation, correlating with cavity deformation and closure mode variation. With increasing angle of attack, the cavity exhibits augmented wavelike undulation and pressure fluctuation. As the wavelength of the flow perturbation approaches the cavity length with increasing gust frequency, the cavity experiences stronger wavelike undulation and internal pressure fluctuation but reduced cavitation number variation.

A numerical study of the bubble induced pressure fluctuation in gas-fluidized beds

2017 ◽  
Vol 314 ◽  
pp. 387-399 ◽  
Author(s):  
Yuli Zhang ◽  
Rui Xiao ◽  
Mao Ye ◽  
Zhongmin Liu
Keyword(s):  
Pressure Fluctuation ◽  
Fluidized Beds ◽  
Numerical Study ◽  
Gas Fluidized Beds

scholarly journals Performance Improvement of a Liquid Molten Salt Pump: Geometry Optimization and Experimental Verification

Symmetry ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 423 ◽  
Author(s):  
Kai Wang ◽  
Xin Lu ◽  
Yu Li ◽  
Xianghui He ◽  
Houlin Liu ◽  
...  
Keyword(s):  
Molten Salt ◽  
Performance Improvement ◽  
Pressure Fluctuation ◽  
Geometry Optimization ◽  
Internal Flow ◽  
Experimental Methods ◽  
Sharp Corner ◽  
Hydraulic Efficiency ◽  
Low Velocity ◽  
Pump Performance

In order to enhance the hydraulic efficiency of a liquid molten salt pump, the improvement on the pump was carried out through numerical and experimental methods. The internal flow field obtained by the numerical simulation was analysed. The results show that there are low-velocity area in the scroll region and large curvature of the streamline at the outlet. Geometric modification was made by trimming the back-blades of the impeller and filleting the sharp corner of the outlet pipe. The modified pump performance was verified by the experiments. The hydraulic efficiency, the pressure fluctuation, vibration characteristics between the original and modified pump were compared. The results showed that the hydraulic efficiency of the modified pump increased 7.4%. In addition, the pressure fluctuation and vibration intensity were also reduced compared with the original pump. This result shows that the geometric modification improves not only the hydraulic performance but also the structural properties.

scholarly journals Numerical study of unsteady flow and exciting force for swept turbomachinery blades

2016 ◽  
Vol 20 (suppl. 3) ◽  
pp. 669-676
Author(s):  
Di Zhang ◽  
Ma Jiao-Bin ◽  
Qi Jing
Keyword(s):  
Boundary Layer ◽  
Unsteady Flow ◽  
Pressure Fluctuation ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Aerodynamic Performance ◽  
Rotor Blades ◽  
Stable Operation ◽  
Straight Blade ◽  
Excitation Force

The aerodynamic performance of blade affects the vibration characteristics and stable operation of turbomachinery closely. The aerodynamic performance of turbine stage can be improved by using swept blade. In this paper, the RANS method and the RNG k-? turbulence mode were adopted to investigate the unsteady flow characteristics and excitation force of swept blade stage. According to the results, for the swept blade, the fluid of boundary layer shifts in radial direction due to the influence of geometric construction. It is observed that there is similar wake development for several kinds of stators, and the wake has a notable effect on the boundary layer of the rotor blades. When compared with straight blade, pressure fluctuation of forward-swept blade is decreased while the pressure fluctuation of backward-swept blade is increased. The axial and tangential fundamental frequency excitation force factors of 15?forward-swept blade are 0.139 and 0.052 respectively, which are the least, and all excitation force factors are in the normal range. The excitation factor of the forward-swept blade is decreased compared with straight blade, and the decreasing percentage is closely related to the swept angle. As for backward-swept blades, the situation is the other way around. Additionally, the change of axial excitation factor is more obvious. So the vibration reduction performance of forward-swept blade is better.

scholarly journals Mixing Characteristics Of Gas-Liquid Flow In A Static Mixer: A Numerical Study

2020 ◽  
Vol 12 (2) ◽  
Author(s):  
Ryan Anugrah Putra
Keyword(s):  
Liquid Velocity ◽  
Numerical Study ◽  
Axial Distance ◽  
Sudden Increase ◽  
Static Mixer ◽  
Mixing Condition ◽  
Mixing Characteristics ◽  
Euler Model ◽  
Gas Liquid Flow ◽  
Liquid Flows

Mixing characteristics of gas-liquid co-current upward flow inside a vertical pipe equipped with a helical static mixer element were numerically investigated. The results from computational fluid dynamics (CFD) simulations with Euler-Euler model of three different length to diameter ratio (L/D) of the static mixer elements were compared. All simulated static mixers provide a better mixing condition in the comparison with the one without a static element. The sudden increase of rotational strength indicated by the liquid velocity curl was observed once the gas-liquid flows enter the static-mixer element zone. The smallest L/D static mixer provides the highest liquid velocity curl in the smallest axial distance providing the most effective mixing process among the tested elements. The best mixing characteristics shown by radial gas distribution was achieved with the static mixer with a smallest L/D.

scholarly journals Experimental and Numerical Study of Gas-Liquid Flow for Gold Nanoparticles Synthesis.

2016 ◽  
Vol 4 (7) ◽  
pp. 1148-1154
Author(s):  
Sabrine Mejri ◽  
◽  
Jalila Sghaier ◽  
Ahmed Bellagi. ◽  
◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Liquid Flow ◽  
Numerical Study ◽  
Nanoparticles Synthesis ◽  
Gas Liquid Flow

Simulation of Two Designs of Micro-Mixers With Enhanced Advection Mechanisms

2011 ◽  
Author(s):  
S. A. Kazemi ◽  
M. Passandideh-Fard ◽  
J. Esmaeelpanah
Keyword(s):  
Numerical Study ◽  
Control Volume ◽  
Numerical Technique ◽  
Chaotic Advection ◽  
Mixing Efficiency ◽  
Mixing Length ◽  
Surface Development ◽  
Mixer Design ◽  
Gas Liquid Flow ◽  
Micro Mixer

In this paper, a numerical study of two new designs of passive micro-mixers based on chaotic advection is presented. The advection phenomenon in a T-shaped micro-mixer is enhanced using a segmented gas-liquid flow; and a peripheral/axial mixing mechanism. The simulations are performed for two non-reactive miscible gases: oxygen and methanol. The numerical model employed for this study is based on the solution of the physical governing equations namely the continuity, momentum, species transport and an equation to track the free surface development. The equations are discretized using a control volume numerical technique. The distribution of the species concentration within the domain is calculated based on which a mixing intensity factor is introduced. This factor is then used as a criterion for the mixing length. In the first micro-mixer design with a drop injection mechanism for a typical condition, the mixing length is reduced by nearly 15%. Compared to that of a simple T-shaped micro-mixer with the same flow rates, the two gases interface area is increased in axisymmetric micro-mixer leading to an increase of the mixing efficiency and a reduction of the mixing length. Also, the effects of the baffles height and span on the mixing efficiency and length in axisymmetric micro-mixer are studied. Having baffles in the channel can substantially decrease the mixing length.

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