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.

scholarly journals Optimization of Centrifugal Slurry Pump Through the Splitter Blades Position

2021 ◽  
Author(s):  
Ehsan Abdolahnejad ◽  
Mahdi Moghimi ◽  
Shahram Derakhshan
Keyword(s):  
Optimal Number ◽  
Centrifugal Pumps ◽  
Slurry Flow ◽  
Suction Surface ◽  
Two Phase ◽  
Flow Rates ◽  
Simulation Tools ◽  
Slip Factor ◽  
Pump Head ◽  
Solid Liquid

Abstract Optimal transfer of two-phase solid-liquid flow (slurry flow) has long been a major industrial challenge. Slurry pumps are among the most common types of centrifugal pumps used to deal with this transfer issue. The approach of improving slurry pumps and consequently increasing the efficiency of a flow transmission system requires overcoming the effects of slurry flow such as the reduction in head, efficiency, and wear. This study attempts to investigate the changes in the pump head by modifying the slip factor distribution in the impeller channel. For this purpose, the effect of splitter blades on slip factor distribution to improve the pump head was investigated using numerical simulation tools and validated based on experimental test data. Next, an optimization process was used to determine the characteristics of the splitter (i.e., length, number, and environmental position of the splitter) based on a combination of experimental design methods, surface response, and genetic algorithm. The optimization results indicate that the splitters were in a relative circumferential position of 67.2% to the suction surface of the main blade. Also, the optimal number and length of splitter blades were 6 and 62.8% of the length of the main blades, respectively. Because of adding splitter blades and the reduction in the flow passage, the best efficiency point (BEP) of the slurry pump moved toward lower flow rates. The result of splitter optimization was the increase in pump head from 29.7 m to 31.7 m and the upkeep of efficiency in the initial values.

scholarly journals Numerical Simulations of a Gas–Solid Two-Phase Impinging Stream Reactor with Dynamic Inlet Flow

Energies ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1913 ◽  
Author(s):  
Xueqing Liu ◽  
Song Yue ◽  
Luyi Lu ◽  
Wei Gao ◽  
Jianlan Li
Keyword(s):  
Residence Time ◽  
Single Particle ◽  
Particle Motion ◽  
Oscillatory Motion ◽  
Two Phase ◽  
Inlet Flow ◽  
Inlet Velocity ◽  
Particle Residence Time ◽  
The Mean ◽  
Inlet Conditions

Fluid flow characteristics and particle motion behavior of an impinging stream reactor with dynamic inlet flow (both inlet velocity patterns exhibit step variation) are investigated and discussed with the computational fluid dynamics–discrete element method (CFD–DEM). The effect of T (variation period of the dynamic inlet flow) and ∆u (inlet velocity difference) on the motion characteristics of single and multiple particles, as well as the mean particle residence time, are studied and discussed. The research results indicate that, compared with the traditional impinging stream reactor (both inlet velocities are equal and constant) with equal mean inlet velocity (um) within one period, the impinging surface is instantaneously moving and the flow regime is varied with time in the impinging stream reactor with dynamic inlet flow. The impinging stream reactor with dynamic inlet flow provides higher cost performance over the traditional impinging stream reactor, under equal um, in terms of single-particle residence time. Moreover, three new particle motion modes exist in multi-particle motions of the impinging stream reactor with dynamic inlet flow; particles are accelerated by the original or reverse fluid and perform oscillatory motion at least once after an interparticle collision. Whether it is a single particle or multi-particles, the mean particle residence time reaches a maximum value when T/2 is approximately equal to the first particle acceleration time, since the maximum axial kinetic energy increases in every oscillatory motion compared with traditional impinging stream, and the number of oscillatory motions is increasing. The mean residence time of a particle in the impinging stream reactor with a dynamic inlet flow increases with increasing ∆u, since the dynamic inlet conditions and increasing ∆u can continuously supply more energy to particles and thus cause more particles to enter one of the three new modes of particle motion.

scholarly journals Influence of Blade Type on the Flow Structure of a Vortex Pump for Solid-Liquid Two-Phase Flow

Machines ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 353
Author(s):  
Hui Quan ◽  
Yanan Li ◽  
Lei Kang ◽  
Xinyang Yu ◽  
Kai Song ◽  
...  
Keyword(s):  
Flow Structure ◽  
Liquid Flow ◽  
Single Phase ◽  
Solid Phase ◽  
Internal Flow ◽  
Phase Flow ◽  
Centrifugal Pumps ◽  
Two Phase ◽  
Vortex Pump ◽  
Solid Liquid

Vortex pumps have good non-clogging performance owing to their impellers being retracted into retraction cavities, but they are much less efficient than ordinary centrifugal pumps. In this paper, numerical simulations were performed on a model of the 150WX200-20 vortex pump for four different blade types, and the influence of blade structure on pump performance was determined. The simulations revealed the existence of axial vortices in the flow passage between the blades in the impeller region. The geometric characteristics of these axial vortices were more regular in two-phase solid-liquid flow than single-phase liquid flow. The presence of the solid phase reduced the vortex strength compared with the single-phase flow and suppressed the increase in size of the secondary circulation vortex. It was found, however, that the blade shape had a greater influence on the circulating flow than the presence of the solid phase. The flow state of the medium flowing out of the impeller domain had a direct effect on the circulating flow with this effect being related to the law governing the flow of the medium in the flow channel between the blades. It was found that the performance of a front-bent blade was the best and that of a curved blade the worst. This influence of blade type on the internal flow structure was used to further explain the relationship between the internal flow structure and the external characteristics of the vortex pump, the understanding of which is crucial for blade selection and hydraulic optimization.

scholarly journals Study on the Effects of the Wear-Rings Clearance on the Solid-Liquid Two-Phase Flow Characteristics of Centrifugal Pumps

Symmetry ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2003
Author(s):  
Chaoshou Yan ◽  
Jianfei Liu ◽  
Shuihua Zheng ◽  
Bin Huang ◽  
Jiacheng Dai
Keyword(s):  
Numerical Simulation ◽  
Centrifugal Pump ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Centrifugal Pumps ◽  
Suction Surface ◽  
Two Phase ◽  
Wear Area ◽  
Fluid Medium ◽  
Solid Liquid

In order to study the wear law of the centrifugal pump flowing surface under different wear-rings clearance, the McLaury wear model was used to conduct the full-passage numerical simulation of solid-liquid two-phase flow in a single-stage single-suction centrifugal pump. The reliability of the numerical calculation method is verified by comparing the experimental data and numerical simulation results. The clearance is 0.1, 0.15, 0.2, 0.3 and 0.5 mm, respectively. The results show that the wear of the centrifugal pump blades is mainly concentrated in the end part and the inlet part of the blade, and the wear of the pressure surface at the end of the suction surface and the front of the blade is more serious. As the clearance increases, the maximum wear value in the impeller increases first and then decreases, reaching a maximum at 0.15 mm. With the increase of the clearance, the wear degree and the wear rate of the volute wall surface first increase and then decrease, and reach the maximum at 0.2 mm. With the increase of the clearance and the concentration of the fluid medium, the wear at the clearance of the centrifugal pump is more serious, and the severe wear area exhibits a point-like circumferential distribution.

scholarly journals Liquid/solid flow field in a centrifugal pump with different impeller blade types by PIV

2021 ◽  
pp. 002029402110223
Author(s):  
Baocheng Shi ◽  
Kun Xue ◽  
Jianpeng Pan ◽  
XingKai Zhang ◽  
Ruomeng Ying ◽  
...  
Keyword(s):  
Flow Field ◽  
Centrifugal Pump ◽  
Vector Fields ◽  
Solid Particles ◽  
Centrifugal Pumps ◽  
Two Phase ◽  
Impeller Blade ◽  
Rotating Speed ◽  
Pressure Surface ◽  
Solid Liquid

In this study, a non-stirred Particle Image Velocimetry (PIV) testing device is developed to measure the flow field in a solid–liquid two-phase centrifugal pump. The pump casing and impeller are made of an organic glass material. Two types of impellers are designed considering different structure parameters. The performance curves of the pump are obtained for the different impellers at a rotating speed of 900 rpm with particle concentrations of 0%, 3%, 5%, and 10%. The flow fields for water and a solid–liquid two-phase mixture for the two impellers are measured utilizing the PIV system in a centrifugal rotating frame at the designed condition. The distribution of the particles, together with its influence on the performance of the different impellers, is analyzed. From a comparison of the relative velocity vector fields, the following can be concluded. First, the pump with a double arc-shaped profile demonstrated a more uniform and stable flow field distribution and higher performance than that with a single arc profile. Secondly, the solid particles were distributed mainly at the outlet of the impeller and volute wall, whereas the concentration distribution of the larger particles tended to match the pressure surface. This research can provide theoretical guidance for the design and optimization of two-phase flow centrifugal pumps.

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.

The Lifting Efficiency of Coarse Particles in Vertical Pipes

2011 ◽  
Vol 66-68 ◽  
pp. 1219-1224
Author(s):  
Hua Chen Pan ◽  
Xiao Qing Tian ◽  
Lei Wu
Keyword(s):  
Average Velocity ◽  
Numerical Study ◽  
Solid Particles ◽  
Phase Flow ◽  
Coarse Particles ◽  
Two Phase ◽  
Average Speed ◽  
Solid Liquid ◽  
Moving Liquid ◽  
Pipe Vibration

A numerical method has been developed to analyze the solid-liquid two-phase flow with coarse particles in vertical pipes. Based on the numerical study, a concept of lifting efficiency has been suggested to describe the efficiency of lifting solid particles by the moving liquid. The lifting efficiency can be defined as, where vs is the average velocity of the solid particles and vl is the average speed of the liquid. It was found that when the liquid speed is lower than 3m/s, the lifting efficiency is increased when the liquid speed is increased. On the other hand if the liquid speed is more than 3m/s, the lifting efficiency will decrease if the liquid speed increases. It was also found that the speed of the particles will decrease if pipe vibration frequency is increased. However the lifting efficiency remains unchanged compared with the stationary pipes.

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