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The use of glass fiber-reinforced polymer (GFRP) composites in fluid transport systems can effectively reduce corrosion damage caused by corrosive media. However, collisions between solid particles and the surfaces of ball valve flow passages can cause erosion damage and lead to safety issues. The two-phase flow and erosion characteristics of ball valves manufactured from resin-based fiber-reinforced composite materials were studied under different openings and particle sizes using the CFD-DPM method. The results indicate that both smaller and larger relative openings are prone to erosion damage at the thin edges of the valve ball. As the relative opening increases, the average erosion amount in the flow passage first increases and then decreases. The maximum average erosion amount is 0.0051 kg/m2·s when the relative opening is Cv = 40. At Cv = 40, erosion damage in the flow channel mainly occurs at the bottom of the inlet flow channel and the valve seat position. With increasing particle size, both the average and maximum erosion amounts in the flow channel increase. Larger particle sizes in the inlet flow channel significantly raise the erosion rate nearby, while at other locations, larger particle sizes mainly increase the erosion rate in the same area. During the use of GFRP valves, it is important to avoid introducing large-sized particles into the medium. Keeping the valve's relative opening greater than 40 and using more erosion-resistant materials for the valve seat can effectively reduce the erosion of the composite ball valve and extend its service life. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive numerical investigation of erosion in bends equipped with inner rings as a novel geometric concept for erosion control. The research aims to assess the effectiveness of these innovative configurations in reducing erosion through rigorous computational fluid dynamics (CFD) simulations. Numerical modeling for the gas-solid two-phase flow has been carried out based on one-way coupling using an Eulerian-Lagrangian approach. The CFD model employed in this work incorporates the RNG k-ε turbulence model for flow solution, the Oka model for simulating surface erosion, and the Grant and Tabakoff model to account for particle-wall collisions. The primary focus of the investigation is to evaluate the erosion reduction capabilities of different inner ring configurations. By systematically varying the number of inner rings, the study elucidates the influence of this parameter on erosion mitigation. The obtained numerical results are analyzed in terms of erosion patterns, erosion reduction percentages, and the integral erosion surface criterion. The findings reveal the elbow with two separate inner rings as the most effective configuration, exhibiting a remarkable decrease in erosion of up to 43 % compared to the standard elbow. Moreover, based on the integral erosion surface criterion, the elbow with five separate inner rings emerges as a more desirable alternative to the standard elbow. In addition, the study investigates the impact of an elbow with helical inner rings configuration on erosion. It is observed that this configuration intensifies flow velocity, thereby accelerating particle motion and leading to increased erosion along the outer wall.

The Eulerian–Lagrangian method was used to establish a numerical model of a multi-elbow pipeline erosion and examine the erosion of the relief line elbow under supercritical conditions. The model was used to examine the effects of the discharge volume, sand content, and shape factor of sand on multi-elbow erosion and those of the connection length on double-elbow erosion. The erosion mechanism and law of multi-elbow lines under gas–solid two-phase flow conditions were revealed. The results indicated that the most severe erosion of the elbow occurred on the impact surface. However, the erosion area of the multi-elbow was relatively long. In a multi-elbow pipeline, the maximum erosion rate of the outlet elbow was 84 times that of the inlet elbow. For the multi-elbow pipeline, the erosion rate was related to the discharge volume, sand content, particle shape, and length of the connection between elbows. The erosion rate of the elbow at the outlet decreased gradually and stabilized with an increase in the connection length. [ABSTRACT FROM AUTHOR]

The use of glass fiber-reinforced polymer (GFRP) composites in fluid transport systems can effectively reduce corrosion damage caused by corrosive media. However, collisions between solid particles and the surfaces of ball valve flow passages can cause erosion damage and lead to safety issues. The two-phase flow and erosion characteristics of ball valves manufactured from resin-based fiber-reinforced composite materials were studied under different openings and particle sizes using the CFD-DPM method. The results indicate that both smaller and larger relative openings are prone to erosion damage at the thin edges of the valve ball. As the relative opening increases, the average erosion amount in the flow passage first increases and then decreases. The maximum average erosion amount is 0.0051 kg/m2·s when the relative opening is Cv = 40. At Cv = 40, erosion damage in the flow channel mainly occurs at the bottom of the inlet flow channel and the valve seat position. With increasing particle size, both the average and maximum erosion amounts in the flow channel increase. Larger particle sizes in the inlet flow channel significantly raise the erosion rate nearby, while at other locations, larger particle sizes mainly increase the erosion rate in the same area. During the use of GFRP valves, it is important to avoid introducing large-sized particles into the medium. Keeping the valve’s relative opening greater than 40 and using more erosion-resistant materials for the valve seat can effectively reduce the erosion of the composite ball valve and extend its service life.

The phenomenon of pipeline erosion dominated by sulfur particles has become a key research target for sulfur-containing gas-gathering pipelines. Gas-solid two-phase flow of sulfur-containing gases is simulated with a coupled CFD-DPM model in this paper. The Realizable k-ε turbulence model was used to determine the changes in the complex flow field and the Euler-Lagrange method was used to describe the specific trajectory of sulfur particles in the complex flow field. The main erosion trace distribution and the effect of secondary flow effects at the elbow were analyzed and the erosion distribution pattern was investigated for different curvature ratios, particle sizes, and pipe diameters. The results show that the formation of erosion along the tip of the V-shaped erosion trace on the outlet sidewall of the elbow may be related to secondary flow effects. The increase of the curvature ratio RD reduces the erosion intensity of the maximum erosion area, but subsequent increase will result in new secondary erosion trace near the outlet of the elbow and reach the maximum when RD = 8. Variations in particle size will have a significant effect on the extent of the erosion distribution, causing the main erosion distribution of the elbow to vary between 48.2° and 84.2°, while variations in pipeline diameter will have a lesser effect. The Stokes number can also be reduced by controlling the variation in particle size and pipe diameter to alter the force profile on the particles and reduce the erosion effect. [ABSTRACT FROM AUTHOR]

Under the condition of nitrogen drilling and blowout in an oilfield, the high-speed gas carried cuttings to the wellhead equipment, causing erosion and wear damage to different degrees, especially the erosion and wear of the wellhead four-way bypass. To explore the erosion wear law of the wellhead four-way and slow down the wear rate, based on the erosion failure mechanism of gas–solid two-phase flow, this paper uses the CFD simulation software to establish a wellhead four-way fluid domain model and analyzes the erosion and wear causes of the four-way bypass. And studying the erosion and wear law of the wellhead four-way bypass under different gas blowout amount, cuttings mass flow rate, cuttings diameter and cuttings density. Then, the erosion resistance of Ni60, Ni45 and Inconel625 coating materials was analyzed through experimental research, and the erosion resistance coating on the inner wall of the wellhead four-way was optimized. The results show that: (1) With the increase of natural gas emission amount, cuttings content, and cuttings diameter, the bypass erosion rate increases; the cuttings density has no obvious effect on the erosion rate; (2) The coating material with the strongest erosion resistance is Inconel625, followed by Ni45, and Ni60 has the worst erosion resistance. [ABSTRACT FROM AUTHOR]

In order to study the influence of collision between solid particles in gas-solid two-phase flow on erosion, an erosion prediction method based on the Direct Simulation Monte Carlo (DSMC) method for calculation of particle collision and computational fluid dynamics was proposed. Herein, the Eulerian-Lagrangian method was adopted, the gas was taken as the continuous phase, the Navier-Stokes equations were solved, and the particle translation motion was solved by the Discrete Phase Model (DPM). For calculation of particle collision motion, the DSMC method was used to replace the real particles with a small number of sampled particles, and the collision conditions were judged by the corrected Nanbu method. Additionally, the effect of particle collision on elbow erosion rate and particle distribution in gas-solid two-phase flow was studied. The results show that the model error can be significantly reduced by calculating the particle collision with DSMC method, and the average percentage error of Oka model is reduced from 39.2% to 27.4%. For calculation of particle collision, the non-particle area on the inner arch side of the elbow becomes smaller, and the maximum erosion position moves backward 5° along the outer arch axis. Meanwhile, the flanks of the "V-shaped" erosion trace expand outward. Calculating the particle collision with DSMC method could significantly reduce the model error, and due to the small deviation from the experimental results, the Oka model considering particle collision is the best model for erosion prediction.

Sand erosion is a phenomenon whereby solid particles impinging on a wall cause serious mechanical damage to the wall surface. This phenomenon is a typical gas-solid two-phase turbulent flow and can be considered as a multi-physics problem in which the flow field, particle trajectory, and wall deformation interact. On the other hand, aircraft engines operating in a particulate environment are subjected to performance and lifetime deterioration due to sand erosion. In particular, the compressors of aircraft engines can be severely damaged. In order to consider sand erosion in the design phase, it is important to develop a prediction method and to obtain basic data. In the present study, we apply our three-dimensional sand erosion prediction code to a single-stage axial flow compressor. The numerical results for the eroded surface geometry and the performance deterioration showed the same tendency as the experimental results. Moreover, the change in the flow field and the particle trajectories are investigated in order to clarify the erosion mechanisms of the compressor.

Erosion is one of the important reasons for the thickness decrease and perforation of the pipe walls. Understanding the gas–solid two-phase flow pipe erosion mechanism is the basis for monitoring pipe erosion. According to the structural characteristics and working conditions of the gas–solid two-phase flow pipeline in a gas transmission station, a gas–solid two-phase flow pipe erosion finite element model was established and validated by combining it with field test data. Then, the gas–solid two-phase flow pipeline erosion characteristics under different pressures, solid contents, throttle valve openings, and pipe diameters were studied. On this basis, a maximum erosion rate prediction equation was put forward after verification by using actual wall thickness detection data. Results show the following: (1) The absolute error of the maximum erosion rate between the model results and the test datum is ≤10.75%. (2) The outer cambered surface of the bend after the throttle valve is the most seriously eroded areas. (3) The maximum erosion rate increases with pressure, solid content and throttle valve opening increasing, but, along with the change of the pipe diameter, the maximum erosion rate increases at first and then decreases with pipe diameter increasing for throttle valve openings of 20% and 30%, and it decreases with pipe diameter increasing for a throttle valve opening of 50%. (4) A maximum erosion rate prediction equation, involving pressure, solid content, opening of the throttle valve, and pipe diameter, is proposed and is verified that the absolute percentage error between the prediction equation calculation results and the field test datum is ≤11.11%. It would seem that this maximum erosion rate prediction equation effectively improves the accuracy of predicting the gas–solid two-phase flow pipe erosion rate in a gas transmission station.

Sand erosion is a phenomenon whereby solid particles impinging on a wall cause serious mechanical damage to the wall surface. The performance and lifetime of various machines, such as airplanes, ships, gas turbines, and pumps, are severely degraded by sand erosion. This phenomenon is a typical gas-particle two-phase turbulent flow and can be considered as a multi-physics problem in which the flow field, particle trajectory, and wall deformation interact. However, neither the change of the flow field nor the related particle trajectory during the erosion process has been taken into account in conventional simulations. This treatment is physically unrealistic. Hence, we have developed a numerical procedure by which to investigate the sand erosion phenomenon, including the temporal change of the flow field and the wall shape. In the present study, we simulate sand erosion of a 90-degree bend with a square cross-section. Bend erosion is the typical subject of sand erosion experiments and is useful for the verification of numerical simulations. The numerical results are compared with experimental data and it is confirmed that the developed code can capture the sand erosion phenomenon reasonably.

Due to the low leaching rate of heavy metals and high energy utilization, the plasma melting furnace is widely used in the harmless treatment of waste incineration. In this paper, the gas-solid two-phase flow in the plasma melting furnace was numerically modelled by means of Euler-Lagrange approach. Conclusions can be drawn that the raw fly ash should be pelletized in order to successfully participate in the melting reaction and effectively avoid the collisional erosion with the graphite cathode. The velocity and temperature fields in the furnace showed asymmetry due to the interaction between the flue gas and slag particles. The heat-up degree of fly ash was much greater than that of SiO 2 particle while the speed discrepancy was small. The average temperature of slag particles in the effective melting region was relatively higher, which is more beneficial to the melting reaction. In addition, three evaluation indicators were established to analyze the distribution of slag particles on the bath surface. The mass proportions of different slag particles in the effective melting region were >40%, the maximum value of their radial distribution can be obtained in the radius range of 0.9–1.0 m, and the mass ratios of fly ash and SiO 2 particles in the same radius domain were overall closer to that of entering the furnace. Finally, the collisional erosion effect of slag particles on the graphite cathode was discussed in detail. [Display omitted] • Particle flow in the plasma melting furnace is studied by Euler-Lagrange approach. • Fly ash pelletizing facilitates melting reaction and avoids collisional erosion. • Distribution of particles on bath surface can be evaluated by three key indicators. • High portion of particles in the effective melting region benefits melting reaction. [ABSTRACT FROM AUTHOR]

Erosion of particles in elbows mounted in series is a detriment in the course of natural gas transmission. The flow and erosion characteristics of π-shaped pipelines were investigated via coupling the computational fluid dynamics (CFD) and the discrete phase model (DPM) method. The effect of pipe orientation on particle erosion was mainly studied. Spiral and asymmetrical trajectories of particles were observed from the second elbow to the downstream straight pipe of the fourth elbow in the non-coplanar π-shaped pipelines. The integral erosion rate of the first elbow increased by 0.35%, and it grew by 72.49% and 87.48% in the second and fourth elbows in non-coplanar structures, respectively, while the integral erosion rate of the third elbow reduced by 32.94%. In the actual transportation of natural gas, it is necessary to make local thickening treatment of the second and fourth elbow of the non-coplanar π-shaped pipelines. [Display omitted] • A swirling effect was discovered in non-coplanar structures. • Spiral and asymmetrical particle trajectories were generated. • Integral erosion degree of fourth elbow increased by 87.48% due to swirling effect. • The erosion rate increased exponentially with the increase of velocity. [ABSTRACT FROM AUTHOR]

The purpose of the present study is to simulate the continuous bend erosion process in different directions, using the dense discrete particle model (DDPM). The influence of the length of the straight pipe in the middle of the continuous bend is investigated. The Rosin–Rammler method is introduced to define the diameter distribution of erosion particles, which is theoretically closer to the actual engineering erosion situation. The numerical model is based on the Euler–Lagrange method, in which the continuous phase and the particle phase are established on a fixed Euler grid. The Lagrange model is used to track the particles, and the interaction between particles is simulated by particle flow mechanics theory. The velocity field distribution, pressure variation, and turbulent kinetic energy of gas–solid two-phase flow, composed of natural gas and gravel in the pipeline, are studied. The simulation results, using the one-way coupled DPM and the four-way coupled DDPM, are compared and analyzed. The results show that the DDPM has good accuracy in predicting the distribution of the continuous bend erosion processes in different directions. The erosion rates of particles with an average distribution size of 50 μm are significantly increased (8.32 times), compared with that of 10 μm, at the same gas transmission rate. It is also indicated that it is important to consider the impact between particles and the coupling between fluid and particles in the erosion simulation of the continuous elbow when using the CFD method. [ABSTRACT FROM AUTHOR]

Pneumatically conveyed particles are commonly responsible for triggering the erosion process by impacts on the wall. Elbows with hemispherical protrusions had been proposed to mitigate erosion. Numerical simulations were carried out using the experimentally verified CFD-DPM method. The continuous impact of particles and secondary flow made the erosion scar on the extrados surface appear as an ellipse with v. For a single row of protrusions, a small arrangement angle and a large protrusion radius is more effective in improving the erosion resistance of the elbow. When θ = 30° and r = D /6, the maximum erosion rate could be reduced by up to 36.59%. The multiple rows of protrusions further mitigated the erosion of the elbow and can reduce the maximum erosion rate by 39.09% at most, but it will cause greater flow resistance. • Protrusions can reduce the maximum erosion rate by 39.09% at most. • Multiple rows of protrusions have a better effect but greater flow resistance. • Protrusions can disperse particle flow, form vortex, and inhibit secondary flow. • A large protrusion radius r and a small position θ are better choices. [ABSTRACT FROM AUTHOR]

Erosion is one of the important reasons for the thickness decrease and perforation of the pipe walls. Understanding the gas–solid two-phase flow pipe erosion mechanism is the basis for monitoring pipe erosion. According to the structural characteristics and working conditions of the gas–solid two-phase flow pipeline in a gas transmission station, a gas–solid two-phase flow pipe erosion finite element model was established and validated by combining it with field test data. Then, the gas–solid two-phase flow pipeline erosion characteristics under different pressures, solid contents, throttle valve openings, and pipe diameters were studied. On this basis, a maximum erosion rate prediction equation was put forward after verification by using actual wall thickness detection data. Results show the following: (1) The absolute error of the maximum erosion rate between the model results and the test datum is ≤10.75%. (2) The outer cambered surface of the bend after the throttle valve is the most seriously eroded areas. (3) The maximum erosion rate increases with pressure, solid content and throttle valve opening increasing, but, along with the change of the pipe diameter, the maximum erosion rate increases at first and then decreases with pipe diameter increasing for throttle valve openings of 20% and 30%, and it decreases with pipe diameter increasing for a throttle valve opening of 50%. (4) A maximum erosion rate prediction equation, involving pressure, solid content, opening of the throttle valve, and pipe diameter, is proposed and is verified that the absolute percentage error between the prediction equation calculation results and the field test datum is ≤11.11%. It would seem that this maximum erosion rate prediction equation effectively improves the accuracy of predicting the gas–solid two-phase flow pipe erosion rate in a gas transmission station. [ABSTRACT FROM AUTHOR]