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The purpose of this paper is to study the transition process from the crystalline particles appearing before the pump inlet to the stable operation of the pump.

Firstly, a modeling test method was put forward for the high-temperature molten salt pump. Then, according to a modeling test scheme, the experiment of the solid–liquid two-phase flow was carried out by using a model pump similar to the prototype pump. Meanwhile, the numerical method to simulate the transition process of a molten salt pump was studied, and the correctness of the numerical model was verified by the experimental results. Finally, the transition process of the molten salt pump was studied by the verified numerical model in detail.

In the simulation of the transition process, it is more accurate to judge the end of the transition process based on the unchanged particle volume fraction (PVF) at the pump outlet than on the periodic fluctuation of the outlet pressure. The outlet pressure is closely related to the PVF in the pump. The variation of the outlet pressure is slightly prior to that of the PVF at the pump outlet and mainly affected by the PVF in the impeller and volute. After 0.63 s, the PVF at each monitoring point changes periodically, and the time-averaged value does not change with time.

This study is of great significance to further improve the design method of molten salt pump and predict the abrasion characteristic of the pump due to interactions with solid particles.

A numerical method is established to simulate the transition process of a molten salt pump, and a method is proposed to verify the numerical model of two-phase flow by modeling test.

The purpose of this paper is to analyze the mechanism of particle erosion in butterfly valve pipelines under hydraulic transportation conditions. The results will affect the sealing and safety of butterfly valve pipelines and hopefully serve as reference for the anti-erosion design of butterfly valve pipelines.

Through the discrete element method (DEM) simulation that considers the force between particles, the detached eddy simulation (DES) turbulence model based on realizable k-epsilon is used to simulate the solid-liquid two-phase flow-induced erosion condition when the butterfly valve is fully opened. The simulation is verified by building an experimental system correctness. The solid-liquid two-phase flow characteristics, particle distribution and erosion characteristics of the butterfly valve pipeline under transportation conditions are studied.

The addition of particles may enhance the high-speed area behind the valve. It first increases and then decreases with increasing particle size. With increasing particle size, the low-velocity particles change from being uniformly distributed in flow channel to first gathering in the front of the valve and, then, to gathering in lower part of it. Fluid stagnation at the left arc-shaped flange leads to the appearance of two high-speed belts in the channel. With increasing fluid velocity, high-speed belts gradually cover the entire valve surface by focusing on the upper and lower ends, resulting in the overall aggravation of erosion.

Considering the complexity of solid-liquid two-phase flow, this is the first time that the DEM method with added inter-particle forces and the DES turbulence model based on realizable k-epsilon has been used to study the flow characteristics and erosion mechanism of butterfly valves under fully open transportation conditions.

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.

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.

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.

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.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2020-0264/

In the process of conveying the solid–liquid two-phase medium of the centrifugal slurry pump, the wear of the flow-passing parts is an important problem affecting its life and safe operation. Therefore, a numerical investigation on the wear characteristics of the centrifugal slurry pump under different particle conditions was conducted.

A solid-liquid two-phase model based on CFD-DEM coupling is established and used to analyze the flow field and the wear characteristics of the flow-passing parts with different particle densities, volume fractions and sizes.

Particle conditions will affect the pump flow field. To analyze the pump wear characteristics, the wear distribution, wear value and cumulative force laws of flow-passing parts under different particle conditions are obtained. In each flow-passing part, with the increase of particle density, volume fraction and size, the wear area is concentrated and the wear depth increases. Under different particle conditions, the wear is mainly on the volute chamber and the blade pressure surface, and the tangential cumulative force of flow-passing parts is much larger than the normal cumulative force.

An accurate model and a coupled simulation method for predicting the wear of the slurry pump are obtained, and the wear characteristic law can provide a reference for the design of the slurry pump to reduce friction.

To analyze the work principle and capacity of energy conversion in each segment of profile lines, the energy transfer from impeller to transmission medium is separated into head coefficient and load coefficient to analyze the energy transfer process. The concepts of airfoil lift coefficient and drag coefficient are used; the third manifestation of the Euler equations is used as well.

The numerical simulation of energy conversion mechanism based on load criteria of vane airfoil has been established in screw centrifugal pump to explain its energy conversion mechanism in an impeller. Upon this basis, the velocity and pressure along the entire blade are investigated through the numerical simulation of internal solid–liquid flow in the pump. The energy conversion process under load criteria in the blade airfoil has also been obtained.

The research suggests that the mathematical model of energy conversion mechanism based on the load criteria of the vane airfoil is reliable in the screw centrifugal pump. The screw centrifugal blade has twice or even several times the wrap angle than the ordinary centrifugal blade. It is a large wrap angle that forms the unique flow channel which lays the foundation for solid particles to pass smoothly and for soft energy conversion. At the same time, load distribution along the profile line on the long-screw centrifugal blade is an important factor affecting the energy conversion efficiency of the impeller.

The quantitative analysis method of energy in the screw centrifugal pump can help the pump designer improve certain features of the pump and shorten the research cycle.

The purpose of the paper is to predict the erosion rate of the components of centrifugal pump under certain operating condition to identify the maximum erosion area and to discuss the factors affecting them. This helps to optimize design and estimate service life.

In the paper, the Eulerian–Lagrangian approach method coupled with the erosion model to investigate the mixed sand characteristics on erosion characteristics of centrifugal pump flow-through wall. The hydraulic performance and wear characteristics experiment of the pump is used to verify the accuracy of the numerical simulation.

The blade erosion area mainly occurs near the blade inlet and the trailing edge of the pressure surface, the main erosion area of the impeller back shroud is near the outlet of the flow passage and the main erosion area of the volute is near the tongue and the I section. With the change of the average diameter and density of sand particles, the average erosion rate on different flow-through walls is positively correlated with the average mass concentration to a certain extent. However, for different sand shape factors, there is little correlation between the average erosion rate and the average mass concentration. In addition, compared with other erosion areas, the increase of average sand particle diameter and density has the greatest impact on the total erosion rate of blade pressure surface, while the shape of sand particles has a greater impact on the total erosion rate of each flow-through wall of centrifugal pump.

In this work, according to the characteristics of the mixed distribution of different sand diameters in the Yellow River Basin, the erosion characteristics of centrifugal pumps used in the Yellow River Basin are studied. The numerical calculation method for predicting the wall erosion of centrifugal pump is established and compared with the experimental results. The results can provide reference for optimizing design and increasing service life.

The purpose of this paper is to experimentally and numerically study the transient hydraulic impact and overall performance during startup accelerating process of mixed-flow pump.

In this study, the impeller rotor vibration characteristics during the starting period under the action of fluid–structure interaction was investigated, which is based on the bidirectional synchronization cooperative solving method for the flow field and impeller structural response of the mixed-flow pump. Experimental transient external characteristic and the transient dimensionless head results were compared with the numerical calculation results, to validate the accuracy of numerical calculation method. Besides, the deformation and dynamic stress distribution of the blade under the stable rotating speed and accelerating condition were studied based on the bidirectional fluid–structure interaction.

The results show that the combined action of complex hydrodynamic environment and impeller centrifugal force in the startup accelerating process makes the deformation and dynamic stress of blade have the rising trend of reciprocating oscillation. At the end of acceleration, the stress and strain appear as transient peak values and the transient effect is nonignorable. The starting acceleration has a great impact on the deformation and dynamic stress of blade, and the maximum deformation near the rim of impeller outlet edge increases 5 per cent above the stable condition. The maximum stress value increases by about 68.7 per cent more than the steady-state condition at the impeller outlet edge near the hub. The quick change of rotating speed makes the vibration problem around the blade tip area more serious, and then it takes the excessive stress concentration and destruction at the blade root.

This study provides basis and reference for the safety operation of pumps during starting period

Numerous researchers have probed the peristaltic flows because of their immense usage in industrial engineering, biomedical engineering and biological sciences. However, the investigation of peristaltic flow in two-phase fluid of a rotating frame in the presence of a magnetic field has not been yet discussed. Therefore, to fulfill this gap in the existing literature, this paper will explicate the peristaltic flow of two-phase fluid across a rotating channel with the effect of wall properties in the presence of a magnetic field. The purpose of this study is to investigate the two-phase velocity distribution and rotation parameter when magneto-hydrodynamics is applied.

The constituent equations are solved under the condition of low Reynolds number and long wavelength. The exact method is used to attain the subsequent equations and a comprehensive graphical study for fluid phase, particulate phase velocity and flow rates are furnished. The impacts of pertinent parameters, magnetic field and rotation are discussed in detail.

It is witnessed that the velocity profile of particulate phase gets higher values for the same parameters as compared to the fluid phase velocity. Moreover, the axial velocity increases with different values of particle volume fraction, but in case of magnetic field and rotation parameter, it shows the opposite behavior.

The outcomes of study have viable industrial implementations in systems comprising solid-liquid based flows of fluids involving peristaltic movement.

The investigation of peristaltic flow in two-phase fluid of a rotating frame in the presence of a magnetic field has not been yet discussed. Therefore, to fulfill this gap, the present study will explicate the peristaltic flow of two-phase fluid across a rotating channel with the effect of wall properties in the presence of magnetic field.

The purpose of this paper is to study the flow patterns and particle-particle collisions during the sedimentation of multiple circular particles under gravity at intermediate Reynolds numbers through direct numerical simulations (DNS).

The previously developed lattice Boltzmann-direct forcing/fictitious domain (LB-DF/FD) method is adopted in this work to conduct DNS.

It is found that the number of particle-particle collisions display a linear growth at long times after an initial evolution, resulting in a constant collision rate, which also depends the initial arrangement.

The problem of particle-particle collisions during sedimentation with two kinds of particle density has not been considered before and it is of special importance in various industries.

The purpose of this paper is to describe the development and application of a numerical model for analysis of flow boiling phenomena and heat transfer.

For flow boiling processes, the fluid and vapour flow regimes in connection with the conjugate heat and mass transfer problem for specimen quenching through the entire boiling curve is modelled. Vaporisation and recondensation, the vapour fraction distribution and vapour movement with respect to the liquid are considered in the calculation of the two‐phase flow and heat transfer process. The derived flow boiling model is based on a mixture model and bubble crowding model approach for two‐phase flow. In addition to the conventional mixture model formulation, here special model implementations have been incorporated that describe: the vapour formation at the superheated solid‐liquid interface, the recondensation process of vapour at the subcooled vapour‐liquid interface, the mass transfer rate in the different boiling phases and the microconvection effect in the nucleate boiling phase resulting from bubble growth and detachment.

The model prediction results are compared with experimental data for quenching of a circular cylinder, showing good agreement in boiling state and heat transfer coefficient distribution. Simulation and experiments lead to a better understanding of the interaction of incident flow in the boiling state and the resulting heat transfer.

Fluid temperatures in the range of 300‐353 K and specimen wall temperatures up to 1,000 K are considered.

Flow boiling is an efficient heat transfer process occurring in several technical applications. Application background of the model development is in quenching of complex metallic specimen geometries in liquids subject to fast changing heat fluxes.

A general model for the complex two‐phase boiling heat transfer at high wall temperatures and fast flow conditions that can be used in engineering applications does not yet exist. The results provide detailed information describing the non‐uniform phase change during the complete quenching process from film boiling to pure convection.