Numerical Simulation on Secondary Vortex Rotational Phenomenon for Helically Coiled Water Pipe

2014 ◽  
Vol 687-691 ◽  
pp. 684-687
Author(s):  
Ling Di Tang ◽  
Shou Qi Yuan ◽  
Yue Tang
Keyword(s):  
Numerical Simulation ◽  
Velocity Distribution ◽  
Flow Rate ◽  
Cross Sections ◽  
Internal Flow ◽  
Curvature Radius ◽  
Secondary Vortex ◽  
Water Pipe ◽  
Turbulence Condition ◽  
Secondary Vortices

Helically coiled water pipe is widely used in industry, agriculture and other areas. But few researches have been done on its internal secondary vortex rotational phenomenon. In this paper, the helically coiled water pipe was simulated by CFD software. The secondary vortex structure and its rotational development process in typical cross-sections, and the secondary flow velocity distribution, the axial velocity distribution were researched by numerical simulation. The realizable k-ε model with swirl correction was selected to solve governing equations. It is found that the secondary vortices positions are 45° symmetry in turbulent condition within the range of its working flow rate. The secondary vortices positions vary from vertical symmetry to 45° symmetry when the internal flow of helically coiled pipe translates from laminar condition to turbulence condition. In addition, with the curvature radius increasing, the flow rate that the positions of secondary vortices vary to 45° symmetry will grow up.

scholarly journals The application of the elastic tube with the specific cross section form in the linear peristaltic pump

2020 ◽  
Vol 329 ◽  
pp. 03062
Author(s):  
Alexander Grishin
Keyword(s):  
Numerical Simulation ◽  
Flow Rate ◽  
Cross Sections ◽  
Elastic Tube ◽  
Smooth Transition ◽  
Peristaltic Pump ◽  
Compression Region ◽  
High Pressure Range ◽  
Volume Method ◽  
Section Form

The article presents a study of the tube form influence on performance of the peristaltic pump with the linearly placed tube and several pushers squeezing it in the transverse direction. The coupled numerical simulation of fluid flow and solid domain deformation was carried out using the software, based on the finite volume method. The cross sections with surface protrusions of two different types are considered for numerical simulation. The simulation results have shown that protrusions without a smooth transition at the tube walls reduce the compression ratio of the tube and therefore yield the flow rate reduce. Protrusions with s smooth transition at the tube walls on the contrary increase the flow rate in a high pressure range. Higher flow rate and pressure values achieved in the case of surface protrusions placed in the first compression region of the tube only. Comparison of pump characteristic curves shows that the use of tube surface protrusions can significantly increase the energy efficiency of the pump.

Numerical Simulation of Internal Flow Field in Mixed Flow Fan

2013 ◽  
Vol 860-863 ◽  
pp. 1589-1593
Author(s):  
Yan Zhao Zhai ◽  
Hong Ming Zhang
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Velocity Distribution ◽  
Pressure Distribution ◽  
Three Dimensional ◽  
Internal Flow ◽  
Field Structure ◽  
Mixed Flow ◽  
Flow Phenomenon ◽  
Impeller Outlet

The numerical simulation of internal flow field of a mixed-flow fan was carried out on the star-CD platform. Three-dimensional steady turbulent flow is calculated using the standard k-ɛ turbulence model, and the pressure distribution, velocity distribution and other important flow phenomenon inside the fan are obtained. The number of meshes has important influence on the result, meanwhile, fan inlet, impeller, outlet interact with each other. The results of numerical simulation can accurately analyze the fan flow field. The results of numerical simulation can accurately analyze the fan flow field structure, and provide guidance for further optimization and improvement of the fan.

Velocity Profile Investigation of FFS Microchannel at Re 100

2014 ◽  
Vol 487 ◽  
pp. 290-293
Author(s):  
Vithyacharan Retnasamy ◽  
Zaliman Sauli ◽  
Steven Taniselass ◽  
Nor Shakirina Nadzri ◽  
Tan Hsio Mei ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Fluid Flow ◽  
Velocity Profile ◽  
Velocity Distribution ◽  
Cross Sections ◽  
Flow Behavior ◽  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Step Height ◽  
Forward Facing Step

Recently, microfluidics system has been widely employed in various areas for instance biomedical,pharmaceuticals and cell biological researchdue to its advantages. The flow behavior in microchannels with different cross-sections has been topic in previous studies. In this paper, numerical simulation of fluid flow in Forward Facing Step (FFS) configuration was performed to investigate velocity profile after the step. Reynolds numbers (Re) 100 with different step heights, 1μm and 3μm were used to observe trend occurs in the flow characteristics. The result illustrated an increase of velocity distribution with the increase of the step height.

Effect of Inlet Prewhirl on Flow Field of Axial Flow Fan

2013 ◽  
Vol 732-733 ◽  
pp. 571-576
Author(s):  
Zhou Ye ◽  
Hai Yang Zhao ◽  
Yang Yang ◽  
Chun Li ◽  
Wei Gao
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Flow Rate ◽  
Flow Separation ◽  
Central Area ◽  
Axial Flow ◽  
Internal Flow ◽  
Field Structure ◽  
Suction Surface ◽  
Flow Loss

The flow in a single-stage fan is analyzed through numerical simulation. The results indicate that there exists a best prewhirl angle which can make flow loss minimal at a given flow rate. So we can improve the internal flow field structure by changing the prewhirl angle, thus the fan efficiency can be raised. In addition, the flow separation on the suction surface is sensitive to the variation of the prewhirl angle. The range of the separation on suction surface increases with the decrease of the prewhirl angle, and expands to the central area of the blades.

scholarly journals Investigation of Transient Flow in a Centrifugal Charging Pump during Charging Operating Process

2014 ◽  
Vol 6 ◽  
pp. 860257 ◽  
Author(s):  
Fan Zhang ◽  
Shouqi Yuan ◽  
Qiang Fu ◽  
Feng Hong ◽  
Jianping Yuan
Keyword(s):  
Numerical Simulation ◽  
Transient Process ◽  
Flow Rate ◽  
Nuclear Power ◽  
Power Plants ◽  
Large Scale ◽  
Transient Flow ◽  
Internal Flow ◽  
Operating Conditions ◽  
Variable Operating Conditions

Centrifugal charging pumps are important components of nuclear power plants and must be operated under multioperating conditions for the requirements of the system. In order to investigate the internal flow mechanism of the centrifugal charging pump during the transient transition process of charging operating from Q = 34 m3/h to Q = 110 m3/h, numerical simulation and experiment are implemented in this study. The relationship between flow rate and time is obtained from the experiment and worked as the boundary condition to accurately accomplish the numerical simulation during the transient process. External and internal characteristics under the variable operating conditions are analyzed through the transient simulation. The results show that the liquid viscosity, large scale vortexes exist in the flow passages in the beginning of the variable operating conditions, which indicates flow separation and the sudden changes in direction of velocity. As the flow rate increases gradually, the flow angles of the fluid in inlet accelerate correspondingly and the flow along the blade is more uniform, which leads to a decrease and movements of the vortexes. The contents of the current work can provide references for the design optimization and fluid control of the pump used in the transient process of variable operating conditions.

Numerical Simulation and Analysis of 3-D Internal Flow Field in Mechanical Turbulent Coal Pulverizer

2012 ◽  
Vol 170-173 ◽  
pp. 3300-3303
Author(s):  
Wei Lv ◽  
Zhi Yue Yao ◽  
De Li Zhang ◽  
Xin Hai Wang ◽  
Xiao Nan Zhang ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Numerical Simulation ◽  
Flow Field ◽  
Velocity Distribution ◽  
Secondary Flow ◽  
Eddy Current ◽  
Gas Flow ◽  
Internal Flow ◽  
Flow Phenomenon ◽  
Computation Fluid Dynamics

In this paper, the computation fluid dynamics ( CFD) software FLUENT is applied to analyze the internal 3-D gas flow of the mechanical turbulent coal pulverizer impeller, especially on the pressure and velocity distribution. Eddy current-wake and secondary flow phenomenon is found in the pulverizer.

scholarly journals Investigation on influences of loose gas on gas-solid flows in a circulating fluidized bed (CFB) reactor using full-loop numerical simulation

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Pengju Huo ◽  
Xiaohong Li ◽  
Yang Liu ◽  
Haiying Qi
Keyword(s):  
Numerical Simulation ◽  
Flow Rate ◽  
Gas Flow ◽  
Circulating Fluidized Bed ◽  
Separation Efficiency ◽  
Circulation Rate ◽  
Solid Mass ◽  
Gas Flow Rate ◽  
Gas Leakage ◽  
Mass Circulation

AbstractThe influences of loose gas on gas-solid flows in a large-scale circulating fluidized bed (CFB) gasification reactor were investigated using full-loop numerical simulation. The two-fluid model was coupled with the QC-energy minimization in multi-scale theory (EMMS) gas-solid drag model to simulate the fluidization in the CFB reactor. Effects of the loose gas flow rate, Q, on the solid mass circulation rate and the cyclone separation efficiency were analyzed. The study found different effects depending on Q: First, the particles in the loop seal and the standpipe tended to become more densely packed with decreasing loose gas flow rate, leading to the reduction in the overall circulation rate. The minimum Q that can affect the solid mass circulation rate is about 2.5% of the fluidized gas flow rate. Second, the sealing gas capability of the particles is enhanced as the loose gas flow rate decreases, which reduces the gas leakage into the cyclones and improves their separation efficiency. The best loose gas flow rates are equal to 2.5% of the fluidized gas flow rate at the various supply positions. In addition, the cyclone separation efficiency is correlated with the gas leakage to predict the separation efficiency during industrial operation.

scholarly journals Effect of Air Injection on the Internal Flow Characteristics in the Draft Tube of a Francis Turbine Model

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1182
Author(s):  
Seung-Jun Kim ◽  
Yong Cho ◽  
Jin-Hyuk Kim
Keyword(s):  
Flow Rate ◽  
Draft Tube ◽  
Pressure Fluctuations ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Air Injection ◽  
Low Flow ◽  
Francis Turbine ◽  
Navier Stokes ◽  
Vortex Rope

Under low flow-rate conditions, a Francis turbine exhibits precession of a vortex rope with pressure fluctuations in the draft tube. These undesirable flow phenomena can lead to deterioration of the turbine performance as manifested by torque and power output fluctuations. In order to suppress the rope with precession and a swirl component in the tube, the use of anti-swirl fins was investigated in a previous study. However, vortex rope generation still occurred near the cone of the tube. In this study, unsteady-state Reynolds-averaged Navier–Stokes analyses were conducted with a scale-adaptive simulation shear stress transport turbulence model. This model was used to observe the effects of the injection in the draft tube on the unsteady internal flow and pressure phenomena considering both active and passive suppression methods. The air injection affected the generation and suppression of the vortex rope and swirl component depending on the flow rate of the air. In addition, an injection level of 0.5%Q led to a reduction in the maximum unsteady pressure characteristics.

scholarly journals Optimal Design of Slit Impeller for Low Specific Speed Centrifugal Pump Based on Orthogonal Test

2021 ◽  
Vol 9 (2) ◽  
pp. 121
Author(s):  
Yang Yang ◽  
Ling Zhou ◽  
Hongtao Zhou ◽  
Wanning Lv ◽  
Jian Wang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Centrifugal Pump ◽  
Large Scale ◽  
Internal Flow ◽  
Orthogonal Test ◽  
Centrifugal Pumps ◽  
Initial Model ◽  
Low Specific Speed ◽  
Specific Speed ◽  
Four Levels

Marine centrifugal pumps are mostly used on board ship, for transferring liquid from one point to another. Based on the combination of orthogonal testing and numerical simulation, this paper optimizes the structure of a drainage trough for a typical low-specific speed centrifugal pump, determines the priority of the various geometric factors of the drainage trough on the pump performance, and obtains the optimal impeller drainage trough scheme. The influence of drainage tank structure on the internal flow of a low-specific speed centrifugal pump is also analyzed. First, based on the experimental validation of the initial model, it is determined that the numerical simulation method used in this paper is highly accurate in predicting the performance of low-specific speed centrifugal pumps. Secondly, based on the three factors and four levels of the impeller drainage trough in the orthogonal test, the orthogonal test plan is determined and the orthogonal test results are analyzed. This work found that slit diameter and slit width have a large impact on the performance of low-specific speed centrifugal pumps, while long and short vane lap lengths have less impact. Finally, we compared the internal flow distribution between the initial model and the optimized model, and found that the slit structure could effectively reduce the pressure difference between the suction side and the pressure side of the blade. By weakening the large-scale vortex in the flow path and reducing the hydraulic losses, the drainage trough impellers obtained based on orthogonal tests can significantly improve the hydraulic efficiency of low-specific speed centrifugal pumps.

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