![Erosion damage in a standard elbow [2].](https://www.researchgate.net/profile/Ali-Farokhi-3/publication/327109573/figure/fig16/AS:722560161427456@1549283175115/Erosion-damage-in-a-standard-elbow-2_Q320.jpg)
![Repeated deformation and cutting wear action with impact angle [21].](https://www.researchgate.net/profile/Ali-Farokhi-3/publication/327109573/figure/fig17/AS:722560161443840@1549283175176/Repeated-deformation-and-cutting-wear-action-with-impact-angle-21_Q320.jpg)
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Numerical modeling of sand particle erosion in return bends in gas-particle two-phase flow
Abstract and Figures
In gas and oil industry, erosion damage to pipelines' bends and elbows due to the presence of sand particles has been a challenging issue. In this study, a computational model approach was used to evaluate the erosion rates at different vertical return bends: Sharp bend, standard elbow, 180° pipe bend, and long elbow. The airow in the pipe was simulated using the SIMPLE method and the k -ω SST turbulence model. An Eulerian- Lagrangian approach was used to predict particle trajectories and related erosion rates. Different particle sizes and mass ow rates were considered, and Oka model was used in these simulations to evaluate the erosion rate. Under the same condition, the simulation results indicated that the sharp return bends experienced the highest erosion rates, and the 180° bends experienced the lowest erosion among the studied conffigurations. It was also found that the erosion rate was linearly proportional to the mass ow rate of particles for all cases studied.
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... The comparison of erosion rates for return bends was reported by Farokhipour et al. [27] using a computational approach. Their results showed that, among the studied configurations, the 180° J o u r n a l P r e -p r o o f Journal Pre-proof bend experiences the lowest erosion while the sharp return bend has the highest erosion. ...
... Despite the huge amount of investigations examining various aspects of erosion phenomenon in different geometries, little attention has been paid to study the interaction of solid particles at high concentrations. In summary, most of investigators used one-way or two-way coupling models for the interaction between phases [27,[30][31][32]. Farokhipour et al. [33] simulated the erosion rates for plugged tees and standard elbows. ...
Sand erosion occurs in a host of industrial applications and accounts for one of the key factors in equipment failure. This study investigated sand particle erosion performance of different 90-degree fittings. To this end, a CFD-DEM model was employed and the erosion rates of various fittings carrying particle-laden flows were analyzed. Several cases with different mass loadings were simulated using different coupling models and the erosion-related parameters including erosion rate, particle impact angle, impact velocity and frequency were evaluated. The simulation results at high mass loading showed that the four-way coupling predicts much higher erosion along the bend in the elbows compared with one- and two-way coupling models. In sharp bends and plugged tees, however, the four-way coupling model predicts the lowest erosion due to the cushioning effects generated by the incoming high speed particle collisions with the high concentration of low speed particles near the walls. Therefore, at high and moderate mass loadings the four-way coupling model must be used. Furthermore, it was determined that the plugged tee is the most erosion-resistant bend geometry, due to the cushioning effect and low frequency of particle impingements on the end region.
... The equations of continuity, momentum, and energy are as follows [5,11,40]: ...
Steam turbines play a critical role in power generation systems. Therefore, increasing the efficiency of steam turbines is highly desirable, especially in LP stages. One of the suggested techniques to reduce wetness losses in LP stages is the hot steam injection. In the first section of the present study, the effect of 3D turbine blade span length on wet steam flow parameters is investigated. Then, the performance of various arrangements of hot steam injection holes (single slot, in-line no. 1, in-line no. 2, staggered no. 1, and staggered no. 2) is evaluated and compared. The results demonstrated that the in-line no. 1 arrangement is the best design for hot steam injection. In this arrangement, the wetness and condensation loss are reduced by 79% and 44%, respectively, and the kinetic energy loss is less than the other arrangements. However, the kinetic energy is still about 28% lower than in the no-injection case. Ultimately, excessive kinetic energy reduction due to hot steam injection is prevented by decreasing the injection pressure. As the injection pressure is reduced from 160 to 100 kPa, the kinetic energy, wetness, and condensation loss are reduced by 9%, 40%, and 17%, respectively, compared to the no-injection case.
... Erosion and wear occur in pipes, valves, elbows, and cyclones' bodies. The particle wear results from particulate impact with the walls [19][20][21]. Jafari et al. [15] studied the influence of surface roughness on erosion. Farokhipour et al. [22] and Duarte et al. [23] examined the impact of oneway, two-way, and four-way couplings on the erosion rate in plugged tees and bends using CFD tools. ...
In this study, the effect of roughness of cyclone wall on the rate of erosion and cyclone performance was studied using the CFD technique with the aid of the Ansys-Fluent 19.2 software. The Reynolds stress transport model was used to simulate the airflow turbulence in the rotating flows in the cyclone. The validated computational model was used, and the variations of axial velocity, tangential velocity, collection efficiency, cyclone pressure drop, and rate of erosion for different wall roughness were evaluated. For simulating surface erosion, the Oka model was used. The result of this study revealed that the wall roughness significantly affected airflow behavior in the cyclone and the resulting cyclone performance. In addition, when the wall roughness increased, the wear rate decreased. It was also found that the solid loading and inlet gas velocity significantly affect the erosion rate and even more than that of particle size.
... However, most of these studies are gas-dominated flows. For liquid-dominated cases, there are only a few experimental data on liquid-solid or slurry erosion reported in the literature [5][6][7][8][9] and for elbows in series, more attention has been drawn in recent years [10][11][12][13][14]. ...
Erosion of elbows in series has received more attention recently as many facilities have elbows in series with various orientations and installations. It has been observed from experiments that, for liquid-dominated flows when two elbows are placed in series and with a small distance between them, the maximum erosion takes place in the second elbow. However, it is also necessary to study the effect of the orientation of the elbows because in the oil and gas industry, for example, there are all types of combinations of elbows in series in the field. In this work, experiments were conducted in a 50.8 mm diameter experimental facility considering liquid-solid and liquid-gas-solid flows and one configuration of elbows in series: where the first elbow for both configurations is upward vertical-horizontal and the second elbow orientation is horizontal-vertical downward. Also, the distance between elbows was kept constant (being three diameters). Additionally, Computational Fluid Dynamics (CFD) studies were performed and compared with experiments. After validation and sensitivity studies concerning numerical solutions, a comprehensive numerical study was conducted, taking into account different scenarios regarding the orientation of elbows using three configurations of two elbows in series. The results show that the normal and the 180° configuration of two elbows in series are less sensitive to the gravity orientation for liquid-solid flows than the other two configurations investigated. On the other hand, for liquid-gas-solid flows, erosion changes with gravity orientation. The worst-case scenario for liquid-solid flow is suggested to be the 180° configuration, while for the liquid-gas-solid flow, the 90° configuration. Thus, it is important to understand the erosion behavior with the orientation of the elbows, because erosion can be reduced by changing the orientation or the configuration of elbows in series.
... They found that, for cases with high velocity of carrier fluid, the plugged tees had better performance than elbows for fine particles while, for the large particles, the recirculating region in the plugged section did not affect the particle velocity and resulted in higher erosion rates compared with the standard elbow. Using an Eulerian-Lagrangian approach, Farokhipour et al. [24] evaluated the erosion rates in different vertical return bends including a sharp bend, a standard elbow, a 180°pipe bend and a long-radius elbow. Their results showed that the sharp bends experienced the highest erosion rates, while the 180°bends had the lowest erosion among the bend configurations studied. ...
In many industrial applications, sand erosion wear is the main cause of equipment failure, particularly in the transferring pipeline fittings. In order to reduce the adverse consequences of erosion in bends, in this study the potential usage of plugged tees instead of standard elbows under a wide range of flow conditions is examined. A computational fluid dynamics (CFD) model coupled with discrete element method (DEM) was used and the particle-laden flows with different fluid velocities in the corresponding geometries carrying various entrained particle mass loadings were simulated. The reliability of selected turbulence models as well as rebound and erosion models were verified by comparing the model predictions with the available experimental data. The final simulation model included the E/CRC erosion model, and the Grant and Tabakoff rebound model. The DEM used in the computational model includes the effects of particles rotation and collisions between the particles. The study also considered the effect of modifications of the plugged length of the tee geometries. The simulation results indicated that, as the particle mass loading increases, the effectiveness of plugged tee compared to the standard elbow increases. Moreover, although increasing the plugged length will generally reduce the erosion rate due to the cushioning effect, the rate of reduction depends on mass loading.
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.
In the oil and gas industry, sand particle erosion damage to elbows is a common problem. The ability to predict erosion patterns is of great importance for sizing lines, analyzing failures, and limiting production rates. Computational fluid dynamics (CFD) can be utilized to study the erosion behavior and mitigate the erosion problem for safety purposes and greater equipment longevity. In order to alleviate the adverse results of sand erosion in elbows, the current study investigated the potential of the geometrically induced swirl flow generated from flow passing through a four-lobed twisted pipe upstream of an elbow. To this end, first, the airflow in a standard elbow equipped with different swirl pipes was simulated using the SIMPLE method, then an Eulerian-Lagrangian approach was employed to track the particles, and finally, the erosion rate was computed. The simulation results indicated that the elbow’s maximum erosion rate with twisted pipes placed upstream of the elbow is lower than the one obtained for the standard pipe. In addition, as the twisted pipe position gets closer to the bend, the erosion rate further reduces. Thus, swirling flows provide a promising prospect as a mechanism to control the erosion rate in elbows.
This contribution presents a numerical analysis based on the effects of aerodynamics of the bump-based humpback whale fins available on the turbine blade edge. In this research, performance comparisons have been made based on dual sequestered blades. One of the blades was sinusoidal in shaped with Bumped Lead Edge (BLE) and the other one with Upright Leading Edge (ULE). However, all the blades are based on a similar cross-sectional profile i.e. NACA-012. This research has been based on simulations of Reynold’s number i.e. 1.8.105 of Attack Angle (AA) i.e. from ‘0º - 30º’. At this angle, especially greater than 10º, the BLE has indicated an enhancement in about 3.5% to 9.0% lift and a reducing drag whereas the negligible variation in lifts and minor drag is displayed for AA less than 10º. The findings in this result for BLE have indicated a substantial achievement in aerodynamic features for particular AA.
Solid particle erosion is a micro-mechanical process that removes material from a surface by repeated impact of entrained particles in the flow. Erosion is a leading cause of failure in fluid handling equipment such as pumps, pipes, valves, and fittings. The S-bend geometry is used to redirect flows in automotive, chemical processing, oil, gas, and food handling industries. An investigation was conducted using both computational fluid dynamics analysis and experimental methods to identify the location of maximum erosion. Three S-bend geometries with 12.7 mm inside diameter, r/D ratio of 1.5, three different air velocities and six different particle sizes were used in the current study. The experimental test section was of 12.7 mm inside diameter, r/D ratio of 1.5, and used 150 and 300 µm particle sizes.
In the present study a rule-based fuzzy inference system is used to predict heat transfer and entropy generation of stratified air-water flow in horizontal mini-channel as a function of a wide range of important parameters. Numerical data of our recent study are used to develop and test the system. The GK clustering algorithm is used to cluster the data. Fuzzy rules are generated based on the Sugeno-Yasukawa algorithm by using trapezoidal membership functions. The FATI and FITA approaches are implemented in the inference engine and finally the combination of the two approaches is defuzzified. The Mamdani and logical methods with the Yager operators are used and unified in both approaches. The parametric form of the system is a feature of the present study which can be used as an effective tool to improve the accuracy of the results. The novelty of the present study is the presentation of the generalized diagrams for the developing region of the channel which seems to be useful for engineering applications. In addition, generalized diagrams of average Nusselt numbers as well as total entropy generation can identify the appropriate range of volumetric flow rate ratio and the Reynolds number.
In this study, a new hybrid RANS/LES turbulence model within the framework of the Multi Relaxation Time (MRT) Lattice Boltzmann Method (LBM) was used to study particle dispersion and deposition in a room. For the hybrid RANS/LES method, the nearwall region was simulated by the RANS model, while the rest of the domain was analyzed using the LES model within the framework of the LBM. In the near-wall layer where RANS was used, the k - ϵ turbulence model was employed. To simulate the particle dispersion and deposition in the room, particles with diameters of 10 nm to 10 μm were investigated. The simulated results for particle dispersion and deposition showed that the predictions of the present hybrid method were quite similar to those of earlier LES-LBM. In addition, the predictions of the hybrid model for the particle deposition and dispersion were closer to LES simulation results, as compared to those of the k - ϵ model.
Erosion is a common problem in various parts of the pipeline industry. In this study, computational fluid dynamics is employed for analysis of pipeline erosion due to gas transported particles. Total removed volume and maximum erosion rate in different elbow geometries from 15° to 90°elbows, for a range of mass loadings are studied. Particle tracking is achieved using combination of Eulerian and Lagrangian methods. In the first stage, gas-solid flow is validated for both straight-pipe and elbow geometries. After that, the erosion model is validated with available data for a 90°, 76.2 mm diameter standard elbow. In the final stage, simulations for a range of elbow angles are performed for two different flow orientations: horizontal inlet and outlet flow directions (H-H flow) and the cases in which inlet flows are vertical and outlet flows either lie in the horizontal plane or make some angles with it (V-H flow). In addition to erosion rate, some important particle-wall impact-related variables such as impact speed, impact angle and impact frequency are presented for elbows with different configurations and angles. Results show that, in general, for a fixed inlet condition and bend geometry, maximum erosion rate in the V-H configuration is greater than that for the H-H orientation. However, total annual eroded volume in the H-H configuration is greater than that for the V-H case. In addition, in both V-H and H-H cases, for the range of mass loadings investigated, the maximum erosion rate increases steadily when the elbow angle increases from 15° to 90° but the rate of total eroded volume remains relatively constant for each value of sand rate. Results of this study are helpful in optimal selection of pipeline elbows for erosion protection.