scholarly journals Relationship between wear formation and large-particle motion in a pipe bend

2019 ◽  
Vol 6 (1) ◽  
pp. 181254 ◽  
Author(s):  
Yi Li ◽  
Hebing Zhang ◽  
Zhe Lin ◽  
Zhaohui He ◽  
Jialiang Xiang ◽  
...  
Keyword(s):  
Particle Motion ◽  
Mass Concentration ◽  
Granular System ◽  
Wall Region ◽  
Two Phase ◽  
Pipe Bend ◽  
Discrete Element Method Simulation ◽  
Large Particles ◽  
Solid Liquid ◽  
The Impact

Fine and large particles flowing through a bend in a pipe move differently and therefore erode the pipe differently. This paper simulates solid–liquid two-phase flow containing large particles in a bend and analyses the relationship between the wear formation and particle motion. Wear experiments are carried out using 3-mm glass bead particles at a mass concentration of 1–15%. At the same time, the flow field and the motion of the granular system are obtained in computational fluid dynamics–discrete element method simulation. The wear formation mechanism is revealed by comparing experiments with numerical simulations. The wear rate of the wall surface increases with the mass concentration, while the marginal growth rate decreases as the mass concentration increases. As the mass concentration increases to a certain value, the degree of wear reaches a maximum and remains unchanged subsequently because of the formation of a particle barrier along the bend wall. The particles near the wall region will bounce forward because of the periodic disturbance flow around particles. The impact of mass bouncing particles causes the formation of the erosion ripple on the test sheet.

scholarly journals Numerical Analysis of Single-Particle Motion Using CFD-DEM in Varying-Curvature Elbows

2022 ◽  
Vol 10 (1) ◽  
pp. 62
Author(s):  
Chao Ning ◽  
Yalin Li ◽  
Ping Huang ◽  
Hongbo Shi ◽  
Haichao Sun
Keyword(s):  
Single Particle ◽  
Particle Motion ◽  
Numerical Study ◽  
Area Ratio ◽  
Centrifugal Pumps ◽  
Distribution Law ◽  
Two Phase ◽  
Curvature Ratio ◽  
Critical Components ◽  
Solid Liquid

Centrifugal pumps are the critical components in deep-sea mining. In order to investigate the particle motion in the curved channel of the impeller, three different types of curvature conform to blade profile to simplify the impeller design of pumps. A numerical study is conducted to investigate the flow field in a varying-curvature channel for solid-liquid two-phase flow. The flow of particles within the varying curvature channel is studied by combining the discrete element method (DEM) with computational fluid dynamics (CFD) and a comparison with Particle Image Velocimetry (PIV) test results. The results show that a polyhedral mesh with a small mesh number yields very accurate results, which makes it very suitable for CFD-DEM. Based on this method, the movement of a single particle is compared and analyzed, and the particle-motion law is obtained. The effects of the curvature ratio Cr and area ratio Ar on the motion law for a single particle are studied, and the simulation results are analyzed statistically. The results show that the effect of Cr on both the particle slip velocity and the turbulent kinetic energy only changes its strength, while the distribution law does not change significantly. Compared with the curvature ratio Cr, the area ratio Ar has a greater impact on the particles, and its distribution law becomes clearly different. As the area ratio Ar increases, the arc radius and length of the corresponding particle trajectory decrease.

Solid–liquid two-phase flow and erosion calculation of butterfly valves at small opening based on DEM method

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Benliang Xu ◽  
Zuchao Zhu ◽  
Zhe Lin ◽  
Dongrui Wang
Keyword(s):  
Peer Review ◽  
Two Phase Flow ◽  
Solid Particles ◽  
Phase Flow ◽  
Butterfly Valve ◽  
Two Phase ◽  
Content Type ◽  
Small Opening ◽  
Solid Liquid ◽  
The Impact

Purpose The study aims to decrease the effect of solid particles on a butterfly valve, which will cause seal failure and leakage, providing a reference for anti-wear design. Design/methodology/approach In this paper, computational fluid dynamics discrete element method (CFD-DEM) simulation was conducted to study the solid–liquid two-phase flow characteristics and erosion characteristics of a butterfly valve with a different opening. Findings Abrasion at 10% opening is affected by high-speed jets in upper and lower parts of the pipeline, where the erosion is intense. The impact of the jet on the upper part of 20% opening begins to weaken. With the top backflow vortex disappearing, the effect of lower jet is enhanced. Meanwhile, the bottom backflow vortex phenomenon is obvious, and the abrasion position moves downward. At 30% opening, the velocity is further weakened, and the circulation effect of lower flow channel is more obvious than that of the upper one. Originality/value It is the first time to use DEM to investigate the two-phase flow and erosion characteristics at a small opening of a butterfly valve, considering the effect of inter-particle collision. Therefore, this study carries on the thorough analysis and discussion. At the same opening degree, with increasing of the particle size, the abrasion of valve frontal surface increases when the size is less than 150 µm and decreases when it is greater than 150 µm. For the valve backflow surface, this boundary value becomes 200 µm. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2020-0264/

scholarly journals Dynamic Response Analysis of Retaining Dam under the Impact of Solid-Liquid Two-Phase Debris Flow Based on the Coupled SPH-DEM-FEM Method

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Bailong Li ◽  
Changming Wang ◽  
Yanying Li ◽  
Yiao Liu ◽  
Nan Jiang ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Debris Flow ◽  
Impact Force ◽  
Time History ◽  
Impact Behavior ◽  
Response Analysis ◽  
Two Phase ◽  
Fem Method ◽  
Solid Liquid ◽  
The Impact

Based on the coupled SPH-DEM-FEM numerical method, this paper analyzes the dynamic interaction of solid debris flow particle-liquid debris flow slurry-retaining dam in order to explore the dynamic response of retaining dam under the impact of the solid-liquid two-phase debris flow and delves into the process of the debris flow impact on the dam, the impact force of debris flow, and the elastic-plastic time-history characteristics of the dam under different slopes of trapezoidal grooves. The calculation results show that the coupled SPH-DEM-FEM method can vividly simulate the impact behavior of the solid-liquid two-phase debris flow on the dam, reproduce the impact, climbing, and siltation in the process of the debris flow impact; the dynamic time-history curve of the retaining dam is consistent with the law of the literature, and the result of the debris flow impact force obtained is close to that of the empirical formula. Moreover, this paper studies the impact force distribution of the debris flow impact process. The results have a certain reference value for the study of the dynamic response of the retaining dam under the impact of the solid-liquid two-phase debris flow and the engineering design of the debris flow-retaining dam.

Results of Air Barbotage Experiments Simulating Two-Phase Flow in a CANDU End Shield During In-Vessel Retention

2017 ◽  
Vol 3 (2) ◽  
Author(s):  
Justin H. Spencer
Keyword(s):  
Packed Bed ◽  
Phase Region ◽  
Experimental Investigations ◽  
Wall Region ◽  
Two Phase ◽  
Candu Reactors ◽  
Test Parameters ◽  
Ball Diameter ◽  
The Impact ◽  
Near Wall

This paper presents the results of experimental investigations into two-phase mass transport in a coarse packed bed representing the Canada Deuterium Uranium (CANDU) end shield. This work contributes to understanding of phenomena impacting in-vessel retention (IVR) during postulated severe accidents in CANDU reactors. The air barbotage technique was used to represent boiling at the calandria tubesheet surface facing the inner cavity of the end shield. Qualitative observations of the near-wall two-phase region were made during air injection. In addition, flow visualization was carried out through the addition of dye to the water. Air flow rate, shielding ball diameter, and cavity dimensions were varied within relevant ranges; and the impact of these parameters on the near-wall region was identified. A brief review of the relevant knowledge base is presented, allowing demonstration of the applicability of the test parameters. The observed phenomena are compared to published results involving similar geometries with capillary porous media.

The Numerical Simulation and Performance Analysis of the Vortex Pump for Solid-Liquid Two Phase Medium

2014 ◽  
Vol 527 ◽  
pp. 88-92
Author(s):  
Peng Yun Song ◽  
Hong Li Wang ◽  
Peng Cheng He
Keyword(s):  
Numerical Simulation ◽  
Volume Fraction ◽  
Internal Flow ◽  
Solid Particles ◽  
Two Phase ◽  
Pump Head ◽  
Phase Medium ◽  
And Performance ◽  
Solid Liquid ◽  
The Impact

The numerical simulation of a 3-D model of the internal flow field for a Vortex slurry pump has been analyzed in this paper. The impact of different solids volume fraction on the distribution of solid particle was analyzed. The expression of the pump head and efficiency was derived by the energy equation. The results show that either on the long blades or on the short blades, the content of the solid particles increases with the increasing of the volume fraction. The results by the expression of the pump head and efficiency are compared with the results of the simulations. The conclusions show that the expression results are similar with the numerical simulation results, and the main factors of affecting the inner and outer characteristics are the solid particles.

Measurement of Velocities in Two-Phase Flow by Laser Velocimetry: Interaction Between Solid Particles’ Motion and Turbulence

2008 ◽  
Vol 130 (7) ◽  
Author(s):  
N. Sad Chemloul ◽  
O. Benrabah
Keyword(s):  
Slip Velocity ◽  
Continuous Phase ◽  
Solid Particles ◽  
Homogeneous Fluid ◽  
Two Phase ◽  
Laser Anemometry ◽  
Kolmogorov Length Scale ◽  
Liquid Suspension ◽  
Large Particles ◽  
Solid Liquid

In this work, an experimental method based on laser anemometry with Doppller effects is developed. This allows the measurement of velocities and their fluctuations in a flow of solid-liquid suspension in an ascendant vertical pipe. In order to distinguish between the signals coming from the continuous phase, water, and those of the glass bead particles larger than the Kolmogorov length scale, an electronic logic circuit was incorporated in the measuring equipment. This enabled the study of both the slip velocity of the solid-liquid suspension and the influence of the large particles on turbulence. The results show that a fine particle suspension, which represents a tracer, behaves as a homogeneous fluid. For large particles, we confirmed the existence of a slip velocity and the effect of particle size on the turbulence. The use of two distinct measurement volumes produces good results for the direct measurement of the turbulent length scales. The results show that the presence of solid particles modifies the turbulence characteristics.

scholarly journals Numerical Simulation Prediction of Erosion Characteristics in a Double-Suction Centrifugal Pump

Processes ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1483
Author(s):  
Xijie Song ◽  
Dunzhe Qi ◽  
Lijuan Xu ◽  
Yubin Shen ◽  
Wei Wang ◽  
...  
Keyword(s):  
Flow Rate ◽  
Erosion Rate ◽  
Particle Concentration ◽  
Yellow River ◽  
Centrifugal Pumps ◽  
Two Phase ◽  
Pressure Surface ◽  
Motion Characteristics ◽  
Solid Liquid ◽  
The Impact

The double-suction centrifugal pumps installed along the Yellow River in China face serious sediment erosion due to the high sediment content which causes the poor operation efficiency of the pump units. The particle motion characteristics and erosion characteristics in a pump under different flow rates and different particle concentrations were numerically simulated based on the particle track model of solid-liquid two-phase flow. The results show that the flow rate has a significant effect on the particle tracks and the erosion caused by the particles in the impeller. The total erosion rate is positively correlated with the flow rate, and increases with the increase in flow rate. The vortex and secondary flow in the impeller have obvious influence on the particle trajectory, which increases the particle concentration at the trailing edge of the pressure surface and intensifies the impact erosion in this area. The particles carried by the vortex intensifies the local erosion. The particle concentration mainly affects the erosion rate, but has little effect on the erosion position. The influence of flow rate on pump erosion is greater than that of the particle properties. These results provide a reference for optimization of the design of anti-erosion blades of double-suction pumps and the regulation and operation of pumping stations.

Influence of the Distribution of Dual Cascades on Double Vanes Based on the Solid-Liquid Two-Phase Flow

2015 ◽  
Vol 741 ◽  
pp. 513-516
Author(s):  
Fu Chun Liu ◽  
Jian Rong Zhang ◽  
Dong Wang
Keyword(s):  
Numerical Simulation ◽  
Velocity Vector ◽  
Active Surface ◽  
Simulation Method ◽  
Energy Performance ◽  
Phase Flow ◽  
Two Phase ◽  
Guide Vanes ◽  
Solid Liquid ◽  
The Impact

The relative positional relationship between the stay vanes and guide vanes is researched to analyze the impact on the hydraulic performance of the Turbine based on N-S equations and RNG k-ε turbulence model under the conditions of sandy water with the numerical simulation method. There are main five kinds of the relative positional relationship between the dual cascades is used to analyse the trends of the distribution about the pressure and velocity. The relative circumferential positions between the dual cascades have obviously effect on the flow verified. And the velocity vector and the pressure distribution on the surface of the guide vanes are studied further. The results show that energy performance is best if little circumferential position differences between the dual cascades in two typical conditions. However, the distribution about the pressure and velocity is uneven on the active surface of guide vanes, exacerbating the local abrasion of the vanes.

Centrifugal pump wear for solid–liquid two-phase flows based on computational fluid dynamics–discrete element method coupling

2020 ◽  
Vol 12 (7) ◽  
pp. 168781402093795
Author(s):  
Yi Li ◽  
Xiaodong Zeng ◽  
Wenshuai Lv ◽  
Zhaohui He
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wear Rate ◽  
Discrete Element Method ◽  
Centrifugal Pump ◽  
Mass Concentration ◽  
Discrete Element ◽  
Two Phase ◽  
Flow Passage ◽  
Solid Liquid

In the conveying process of a solid–liquid two-phase medium, the wear of the flow passage components is unavoidable. In this study, the solid–liquid two-phase flow in a centrifugal pump was numerically simulated by computational fluid dynamics–discrete element method coupling. For particle diameters up to 3 mm, the particle–particle and particle–wall interactions were considered in the simulation. Two-phase performance and wear experiments for different flow rates and particle concentrations were conducted. The wear experiment was carried out for 48 h at each mass concentration. In these experiments, a paint film method was used to display the wear position, and the wall thickness of the flow passage was measured using an ultrasonic thickness gauge. The results show that the instantaneous wear rate of the impeller, volute, and wear plate in the pump changed periodically with the impeller rotation. The volute wall wear was related to the particle movement. With the increase in the particle mass concentration, the wear rate increased. However, the rate of increase of the wear rate decreased because the particles moved to the wall in the volute to form a particle layer. Increasing the concentration did not linearly increase the effect of the particles on the wall.

Influence of the Distribution of Dual Cascades on Double Vanes Based on the Solid-Liquid Two-Phase Flow

2015 ◽  
Vol 723 ◽  
pp. 186-189
Author(s):  
Fu Chun Liu ◽  
Jian Rong Zhang ◽  
Dong Wang
Keyword(s):  
Numerical Simulation ◽  
Pressure Distribution ◽  
Velocity Vector ◽  
Active Surface ◽  
Energy Performance ◽  
Phase Flow ◽  
Two Phase ◽  
Guide Vanes ◽  
Solid Liquid ◽  
The Impact

The relative positional relationship between the stay vanes and guide vanes is researched to analyze the impact on the hydraulic performance of the Turbine based on N-S equations and RNG k-ε turbulence model under the conditions of sandy water with the numerical simulation method.There are main five kinds of the relative positional relationship between the dual cascades is used to analyse the trends of the distribution about the pressure and velocity. The relative circumferential positions between the dual cascades have obviously effect on the flow verified.And the velocity vector and the pressure distribution on the surface of the guide vanes are studied further.The results show that energy performance is best if little circumferential position differences between the dual cascades in two typical conditions.However, thedistribution about the pressure and velocity is uneven on the active surface of guide vanes, exacerbating the local abrasion of the vanes.

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