Pipe Bend Research Articles

CFD—ANN study on axial dispersion in helical and serpentine millimetric coils

CFD simulations are reported to compare hydrodynamic/axial dispersion in a classical helical-shaped and planar serpentine-shaped tubular reactor at a millimetric scale (1-5 mm) for the first time. A two-step simulation approach is validated against experimental data on residence time distribution in serpentine coils. The method is then used for parametric analysis to explore the impact of geometric parameters on the coiling factor and axial dispersion coefficient. Dean vortices in the coiling region are visualized. The findings from the parametric analysis are utilized to develop empirical correlations and Artificial Neural Network (ANN) models for estimating coiling factors and axial dispersion coefficients in both serpentine and helical coils. The absolute average relative error (AERR) in predicting the coiling factor is 3.5% for helical coils and 4.6% for serpentine coils. The AERR of the ANN model for predicting the axial dispersion coefficient is 14% for helical coils and 10% for serpentine coils. The study reveals that both axial dispersion coefficient and pressure drop are higher in serpentine coils compared to helical coils. Axial dispersion is found to be relatively unaffected by pitch (helical) or bend diameter (serpentine) and tube diameter but shows significant reduction with a decrease in pitch circle diameter (helical) or gap between bends (serpentine). The developed correlations and ANN models can aid in the precise sizing of tubular reactors designed as helical or serpentine coils. This is exemplified through a case study involving the synthesis of an ionic liquid, where the helical configuration demonstrated a performance advantage of approximately 6% over the serpentine configuration.

Study on microstructure evolution and deformation behavior of Mg– Zn base alloy pipes during hot bending

The strong basal fiber texture of magnesium (Mg) alloy pipes usually leads to poor secondary forming performance. In this study, Mg–2Zn-0.4Ce-0.4Mn (ZME) and Mg–2Zn-0.4Ce-0.4Mn-0.2Ca (ZMEX) pipes were prepared. Compared with the ZME pipe, the ZMEX pipe with a weaker initial texture exhibits excellent bending performance, with a peak load displacement (PLD) of 14.5 ± 0.5 mm and a total energy absorption (TEA) of 142.9 ± 1.7 J. The difference in bending performance between the two pipes is related to the deformation mechanism during hot bending. In the hardening stage, the deformation of the compression zone (CZ) of the two pipes is mainly ETW nucleation, and the overall proportion of twin grains is similar. However, in the tensile zone (TZ), the deformation of the ZME pipe is mainly prismatic slip, while the weak initial texture of the ZMEX pipe leads to the deformation dominated by both prismatic and multiple pyramidal slips, resulting in a higher hardening rate. In the softening stage, the deformation behavior in the CZ and TZ of both pipes tends to be similar. In addition, it is revealed that the softening phenomenon of both pipes after the bending displacement reaches PLD is caused by discontinuous dynamic recrystallization (DDRX) driven by high-density dislocations accumulated in the later CZ and TZ. The research on the microstructure evolution and deformation mechanism of Mg alloy pipe during bending deformation carried out in this study is of great significance for optimizing its secondary forming controllability and further expanding its application.

A multiblock (MIB) finite element method for accurate and efficient blood flow simulation

We present an efficient and accurate immersed boundary (IB) finite element (FE) method for internal flow problems with complex geometries (e.g. blood flow in the vascular system). In this study, we use a voxelized flow domain (discretized with hexahedral and tetrahedral elements) instead of a box domain, which is frequently used in IB methods. We highlight the applicability and efficiency of the proposed method in generating the flow domain mesh and removing unnecessary portions of the domain, compared to the standard IB methods that rely on a full Cartesian mesh. Our approach is attractive for internal flow problems that use IB methods. The proposed method accurately satisfies the boundary conditions on the immersed object using velocity and pressure correction procedures. The velocity correction applies implicitly such that the velocity on the immersed boundary (Lagrangian points) interpolated from the corrected velocity values computed on the mesh nodes (Eulerian nodes) accurately satisfies the prescribed velocity boundary conditions. The proposed method utilizes the well-established incremental pressure correction scheme (IPCS) FE solver, and the boundary condition-enforced IB (BCE-IB) method to numerically solve the transient, incompressible Navier-Stokes (NS) flow equations. We verify the accuracy of our numerical method using the analytical solution for the Poiseuille flow in a cylinder, and the available experimental data (laser Doppler velocimetry) for the flow in a three-dimensional 90° angle tube bend. We further examine the accuracy and applicability of the proposed method by considering flow within complex geometries, such as blood flow in aneurysmal vessels and the aorta, flow configurations that would otherwise be difficult to solve by most IB methods. Our method offers high accuracy, as demonstrated by the verification examples, and high applicability, as demonstrated through the solution of blood flow within complex geometry. The proposed method is efficient, since it is as fast as the traditional finite element method used to solve the Navier–Stokes flow equations, with a small overhead (not more than 5%) due to the numerical solution of a linear system formulated for the IB method.

Analysis of Ovality Deviation of Bending Superheater Tube Boiler Fabrication Process with Six Sigma Method in Manufacturing Company

Quality control in fabrication is critical to the success of the production process. In this study, key factors in production quality control were identified by analyzing the influence on the tube bending process in fabrication work. Ovality deviations occur during the tube bending process that exceeds 9 percent. 30 boiler superheater tube elements had to go through the repair process. The causes of tube bending deviations were analyzed using the Six Sigma approach with the DMAIC (Define, Measure, Analyze, Improve, and Control) methodology. The causes of failure were analyzed using FMEA, and the highest RPN of 320 was obtained due to design planning and manufacturing of bending dies that are in accordance with the OD tube and the placement of clamp die and pressure die distances that are not too far apart. In addition, an RPN value of 294 was obtained due to the bending speed being too high. The recommendation for the next project is to consider using a C-Frame machine with better control to make it easier for operators to adjust the pressure, temperature, and speed of a good machine to better maintain ovality.

CFD Modelling of Swirling Mechanism to Reduce Erosion of Pipe Bend in Pneumatic Conveying System

Dry powders mixed with air transportation had bend erosion issues. CFD analysis by Shear-Stress Transport (SST) k-ɯ Model within Ansys was used to conduct a comprehensive numerical analysis of particle erosion within a 90° mild steel pipe bend in Pneumatic Conveying System. Part of the conveying pipe rotation achieved with the external motor swirling device was used to create swirling of particle before bend. Different-sized sand particles at different rpm were tested with and without a swirling device. Reduction in erosion rate of pipe bend carries significant implications, notably an extension of the system's operational lifespan. Reduction in erosion rate reports an impressive increase of 50% bend lifespan at higher RPM levels of the swirling device. The results underscore the effectiveness of this device in mitigating erosion, with significant implications for enhancing the longevity and reliability of bend life in piping systems of Pneumatic Conveying applications.

Effect of secondary flow and wall collisions on particle-laden flows in 90° pipe bends

Fully developed, statistically stationary particle-laden turbulent flows in a 90° pipe bend at a moderate Reynolds number are studied using direct numerical simulation coupled to a Lagrangian particle tracking technique. Three populations of particles are studied which are two-way coupled with the carrier phase. The focus is the investigation of the effect of strong curvature on particle transport dynamics across a range of particle inertias. A validation of the carrier phase predictions is performed, with good agreement found with available experimental data. It is demonstrated that the presence of particles notably affects the turbulence statistics of the carrier phase, decreasing the mean fluid velocity in the outer bend while slightly increasing it in the inner bend. Two intriguing phenomena emerge: the presence of a particle void near the inner bend and reflection layers near the outer bend. Centrifugal forces are responsible for driving particles to the outer wall, with some rebounding back into the main body of the flow, and others, influenced by the secondary flow in the plane of the pipe cross-section, converging towards the inner wall before re-entering the central pipe region. These effects dictate the size and shape of the particle void region and the formation of reflection layers due to particle-wall collisions. These two phenomena have a significant influence on the particle distribution in the pipe bend, as well as on the first- and second-order moments of the velocity and acceleration of the particulate phase. Finally, a heat map of particle-wall collision statistics indicates that the effect of the secondary flow on particle distribution and particle-wall collisions is not negligible.

Mathematical Analysis of Solid Particles Internal Support to Enhancing Pipe Bending

Airspace, aerospace launch vehicles, and a variety of electrical devices employ low thickness bent pipes with short bending radius as one of their essential components. Producing technology for seamless bends has become essential, as the traditional method of producing such bent pipes involves welding two stamped half bends, which is no longer able to meet the high dependability requirements. This work describes a novel approach of push bending low thickness pipes with modest relative bending radiuses using solid particles internal support. Using the DEM, the pressure distribution of the solid particles is examined (DEM). The main benefit of the solid particles in reducing pipe forming faults, particularly wrinkling, is the strengthening of bending deformation. Furthermore, the study explores how diameter of the particles, solid particles friction, & counter pressure affect distribution of pressure within the system. Solid particles plays a beneficial role in enhancing wrinkle resistance during bending, as demonstrated by the formation of pipes with a high diameter, low thickness, and short bending radius. All of these findings suggest that using solid particles internal support opens up new possibilities for the relative bending radius of low thickness pipes to be bent.

Applicability analysis of induction bending process to P91 piping of PGSFR by high-temperature fatigue test

The application of the induction bending process in pipe fabrication is expanding across industries, significantly reducing leakage by minimizing welded sections in curved pipes. In this study, the applicability of the induction bending process to P91 bent pipes of PGSFR was analyzed, focusing on both material fatigue tests and structural fatigue tests for induction bent pipe at high temperatures. First, both high-cycle and low-cycle fatigue tests on specimens from the bent pipe were carried out at 550 °C to confirm that the fatigue properties meet the ASME Code's fatigue requirements. Second, material constants for a Chaboche combined hardening model were identified by using the material test results and an inelastic finite element analysis of the P91 bent pipe were performed to determine the fatigue test load for structural test effectively. Lastly, a high-temperature fatigue test on the bent pipe structure was performed to assess its structural integrity and post-test non-destructive examination confirmed that no fatigue cracks developed, and thereby affirming the applicability of the P91 bent pipe.

Analysis of Bending Deformation and Stress of 6063-T5 Aluminum Alloy Multi-Cavity Tube Filled with Liquid.

The production of aluminum alloy multi-lumen tubes primarily involves hot bending formation, a process where controlling thermal deformation quality is difficult. Specifically, the inner cavity wall of the tube is prone to bending instability defects under the bending stress field. To address these challenges in the bending deformation of aluminum alloy multi-lumen tubes, a multi-lumen liquid-filled bypass forming method is proposed in this paper. This study focuses on the 6063-T5 aluminum alloy double-lumen tube as the research object. The liquid-filled bending deformation behavior of the aluminum alloy double-lumen tube was investigated, and the deformation theory of the aluminum alloy double-lumen tube was studied. Through experimental and numerical simulation methods, the influence of support internal pressure, bending radius, and tube wall thickness on the liquid-filled bending deformation behavior of the double-lumen tube was examined. The results indicate that when the value of internal pressure was 7.5 MPa, the straightening of the outer wall was improved by 2.51%, the thinning rate of wall thickness was minimized, and the internal concave defect was effectively suppressed. The liquid-filled bending method provides a promising new approach for the integrated bending and forming of multi-lumen tubes.

The performance of transmission pipelines on February 6th, 2023 Kahramanmaras earthquake: a series of case studies

AbstractThe Mw 7.8 earthquake that struck Kahramanmaras on February 6, 2023, caused significant damage to hydrocarbon and water transmission lines due to permanent ground deformations. Explosions occurred in the Kahramanmaras–Gaziantep Natural Gas transmission pipeline causing disruption of gas in the cities of Gaziantep and Hatay Fault Displacement Hazard. Water transmission pipelines were also damaged due to extreme fault offsets. This paper presents the findings from the earthquake affected zones. Particular attention was given to the performance of the 2600 mm diameter Duzbag–Gaziantep water transmission pipeline due to three reported challenges: (#1) The behavior of the pipe in the Duzbag tunnel, (#2) The pipe bend behavior at the fault crossing, and (#3) The pull-out of the pipe at valve room. Based on field observations, extreme damage forms at pipes were presented. A three-dimensional nonlinear numerical analysis was performed to simulate the observed damage of the reoriented water pipe at the fault crossing for Case #2. The nonlinear finite element model was able to capture the complex nature of the post-yield behavior of steel pipe as well as the damage locations along the pipe and their sequence of occurrences. As a mitigation measure for new pipes, the need for using flexible connections at critical crossings was highlighted. For existing pipes, the importance of developing secondary (by-pass) lines was emphasized.

Impacts of mandrel parameters on forming quality of tube bending with small bending radius

Impacts of mandrel parameters on forming quality of tube bending with small bending radius

Innovative Ecofriendly Coconut Husk Brushes

AIM : To reduce the time, energy and labours to cleaning the floor and bathroom by using the of innovative ecofriendly cocnut husk brushes. INTRODUCTION : The outer of almost houses are made by favors, interlocks or tiles or cement. Those are made dirty due to walking or by own vehicles or green algae of thallophytes are grown on the outside floor due to rain and also bathroom become dirty due to daily use. We can easily clean the floor and bathroom by using of the innovative ecofriendly cocnut husk brushes (Innovative Indigenous Floor And Bathroom Cleanig Brushes) in very less time which is made by coir husk. This is eco friendly brush. This brush worked on the principle of Simple Mechanism Theory. METHODS: Take two plates of 1.5x5 inches size of metal plate and these are bent as an arc. 4-5 holes are made on those plates equally for screw nuts. 3 pieces of desirable size of coir husk are cut at one end which becomes a brush. Each coir husk has a hole at another end as shown in the figure. Now, these coir husks are inserted between arc plates and fixed by the help of bolts tightly. Half feet of bent pipe is welded to this one with 60 degree angle as shown in the figure. And then two feet length wooden handle is fixated to this pipe as a handle. Now we can easily clean by rubbing it against the bathroom tiles or outside floor with the help of water. It takes only one minute to clean 1 sq mt area. Comparatively with plastic brush takes three to four minutes. So we can save plenty of time along with being eco friendly. It costs 100 rupees only.

Research on soft measurement model of flow in bends of primary circuits of the nuclear power plant

When measuring the coolant flow in a nuclear power plant using the elbow flowmeter, the complex fluid-heat coupling environment at the measurement location and other factors will affect the accuracy of the flow measurement, and the uncertainty of the influencing factors on the flow measurement needs to be considered to improve the measurement accuracy. To address this problem, this paper adopts the finite element simulation method to simulate and analyze the flow-heat field of the bend section of the primary circuit of a nuclear power plant and optimizes the Optimal Cross-section selection of the pipeline for flow measurement. Based on the pressure values measured using the traditional method, temperature information is added, and a BP neural network bend pipe flow soft measurement model based on the whale optimization algorithm is established to quantify the effects of temperature and pressure on flow measurement. The experimental results show that compared with the traditional engineering empirical method, the average absolute percentage error measured by the soft measurement method is reduced from 2.57 % to 0.21 %, which realizes the accurate measurement of the coolant flow rate of the elbow pipe.

Mechanical Properties of Glass Plate During Anticlastic Cold Bending

Anticlastic glass surfaces play a significant role in free-form glass facades. For realizing anticlastic surface, cold bending by loading at the corner of the plate is more adaptive and more economic than traditional hot bending method. Previous research on anticlastic cold bending mainly focuses on the description of instability phenomenon and qualitative analysis of parameters. However, the failure mechanisms of glass plates during cold bending and the influence of lamination remains unclear. In this paper, the anticlastic cold bending test was conducted to explore the influence of various factors, including aspect ratio, scale and composition of the plates. Subsequently, an effective finite element model was established and validated by test results, which is used for further explore the cold bending controlling condition for better engineering practice. The failure modes are considered as instability and strength failure. For laminated glass, maximum stresses can be derived from monolithic glass based on equivalent thickness method. The instability is induced by the compression area in the middle surface of glass plate which is significantly influenced by the composition of the laminates. Consequently, thin glass laminates exhibit enhanced stability because a reduced glass to PVB thickness ratio changes the compression area from bi-directional to uni-directional.

Mitigation of Erosion Wear Produced by Fly-Ash Slurry on 90<sup>0</sup> Elbow by Changing the Cross-Section Shape and Area Ratio

The predominant method of transporting fly ash involves conveying it in slurry form through pipelines within diverse industrial facilities. The key elements of slurry conveyance encompass bends, pumps, and valves. These components of the pipeline endure significant erosion and wear due to the impact of discrete particles. In this investigation, the study assessed the wear induced by slurry erosion in conventional 900 pipe bend and 900 square section elbows of different area ratios using ANSYS Fluent. The discrete phase model was used to estimate the slurry erosion wear for the fly ash-water suspension. From the investigation, the outcomes from the standard k-turbulence model were discovered to be in agreement with the experimental data. This study also looked at a number of other influencing factors, such as the solid concentration and velocity. The analysis reveals that the average erosion wear is lower in the square cross-section elbow compared to the standard elbow. Furthermore, the erosion wear is observed to decrease further with an increase in the cross-sectional area of the square section elbow.

Experimental study of pipeline pressure loss laws with large-size gangue slurry during the process of industrial-grade annular pipe transportation

Gangue grouting and backfilling mining technology is one of the key techniques to achieve solid waste disposal and rock movement control in coal mines. The pipeline conveying performance of gangue slurry determines the success or failure of backfilling engineering directly. Due to the high cost of crushing small-sized gangue, research on pipeline transportation of large-sized gangue slurry has been gradually highlighted. In this study, the gangue slurry ratio optimization test and industrial-grade pipeline transportation experiments were conducted, and the optimal ratio of gangue slurry with different large particle size grading was obtained. Additionally, the rheological parameter changes of gangue slurry in pipeline transportation were analyzed, and the changes in slurry mass concentration, slurry flow velocity, and particle size matching of pressure loss in the straight and bent pipe sections of the transportation pipeline were studied. The results show that the optimal ratio for the 0–5 mm particle size gangue slurry is the mass concentration of 65 % and a mass proportion of 0.3: 2: 1 for 2–5 mm, 0.15–2 mm, and 0–0.15 mm particle size gangue; the optimal ratio for the 0–2 mm particle size gangue slurry gangue is the mass concentration of 60 % and a mass proportion of 2:1 for 0.15–2 mm and 0–0.15 mm particle size gangue. Both the mass concentration, flow velocity, and particle size grading of the gangue slurry have a significant impact on the pressure loss during pipeline transportation. The mass concentration of the gangue slurry has the most significant impact on the pressure loss in the straight pipe section, while the flow velocity has the highest impact on the pressure loss in the bent pipe section. The research results provide a theoretical basis for the design of pipeline transportation parameters for gangue grouting and backfilling projects.

Effect of tube bend angle on liquid propulsion system priming event pressures

Experimental work was performed to measure the priming event pressure transient levels in unrestricted liquid propulsion system tubing. An existing water hammer experimental setup was utilized, where system tubing diameter, length, and bend angle were examined. Experiments were performed under both atmospheric and low-pressure pre-test element conditions to understand any impact of tube bend angle on the mitigation of priming event pressure transients inside the liquid system. Experimental results showed pressure levels were influenced by a combination of tube diameter, length, and pre-test pressures; however, tube bend angle had minimal to no discernible change on the average peak pressure levels or rise times to peak pressure for all conditions examined.

Towards high-accuracy axial springback: Mesh-based simulation of metal tube bending via geometry/process-integrated graph neural networks

Springback has always been a stubborn defect that affects the axial accuracy of metal bending. The finite element simulation of springback enables effective control and precise compensation to improve the forming quality. Affected by the material, size, and forming process, the generation pattern of the springback defect remains further exploration. Graph-based deep learning techniques support differentiable high-dimensional physics simulations with significantly lower computational resources and comparable accuracy. In this paper, a framework based on geometry/process-integrated Graph Neural Networks (GNN) is presented for simulating axial springback of mesh-based metal bending, with a specific focus on the tube bending. The framework adopts an encode-process-decode structure, equipped with parallel graph network blocks and data augmentation strategy, to capture the axial springback information with high fidelity in a form of mesh. Comparative experiments reveal that our framework achieves an accuracy comparable to that of finite elements method, yielding an average nodal error below 1 mm and outperforming three representative GNN baselines. The framework remarkably enhances the simulation efficiency, exhibiting a four-order-of-magnitude improvement on CPU and a six-order-of-magnitude improvement on GPU compared to finite elements method. Furthermore, we successfully apply the proposed framework to simulate the springback of plate V-bending, showcasing its robust generalization ability. These results illustrate the capability of our GNN framework to achieve the accurate and real-time springback simulation, with significant implications for digital twin development and bent tube quality optimization.

Research on engineering technology of compact thermoacoustic air conditioner for vehicles

Thermoacoustic refrigeration technology presents a promising solution for sustainable and efficient air conditioning in vehicles. However, traditional thermoacoustic systems typically employ rigid resonant tubes, which pose challenges in terms of assembly and spatial layout during experimentation. Additionally, electric heating is predominantly utilized as the heat source in most experimental setups.To address the need for compact thermoacoustic air conditioning systems suitable for vehicle applications, this paper introduces the concept of employing flexible resonant tubes in heat-driven thermoacoustic refrigeration systems. Our study begins by constructing a heat-driven thermoacoustic refrigeration platform designed to simulate real automotive exhaust conditions. The DeltaEC software is employed to optimize the design of each component within the system.Both flexible and rigid resonant tubes are used in experimental research. Our findings reveal that the pressure amplitudes measured from experiments using both types of tubes closely match the simulated sound field. Operating at 8.7 MPa, the cooling capacity of the thermoacoustic system with flexible tube is 3.4 kW at 10 ℃. Using more gentle bending of flexible resonant tubes can reduce small losses caused by bending in rigid resonant tubes. Consequently, under similar working conditions, the cooling capacity generated by the system employing flexible resonant tubes slightly exceeds that of systems employing rigid resonant tubes. Furthermore, our study demonstrates a thermoacoustic conversion efficiency of 20.8 % and a refrigerator refrigeration efficiency of 2.34.These findings provide empirical validation for the use of flexible resonant tubes within vehicle exhaust heat-driven thermoacoustic refrigeration systems. The experimental results clearly demonstrate the ability of vehicle exhaust as a heat source to provide heat for thermoacoustic systems, and the ability of flexible thermoacoustic systems to generate sufficient cooling capacity. Ultimately, this research contributes to the advancement and practical implementation of thermoacoustic air conditioning within vehicles.

Hybrid aeroacoustic investigation of turbulent 90° pipe bend flow with source terms from Large-Eddy Simulation

The internal, low Mach number, turbulent flow-induced acoustic field of a cylindrical 90° pipe bend with a curvature radius Rm/D=1.02 is investigated using hybrid Computational Aero-Acoustics (CAA). Incompressible Large-Eddy Simulation (LES) is used to computationally describe the turbulent flow field at bulk Reynolds numbers ReB=5000,12000,26000 and 66000. The incompressible LES predicts all salient flow features, like the separation from the inner wall of the bend followed by a turbulent recirculation zone, in good agreement with literature. The internal flow-induced noise is predicted by Acoustic Propagation Simulations (APS) applying Lighthill’s Equation (LE), Ribner’s Dilatation Equation (RDE) and the Perturbed Convective Wave Equation (PCWE), provided with acoustic source terms obtained from the incompressible LES. The turbulent recirculation zone is the most active region for generating acoustic sources. Among the two constituent components of the PCWE source term, the local pressure time derivative term turned out as clearly dominant in this region, so that PCWE and RDE predicted similar acoustic fields. The sub-grid scale (SGS) model applied in LES notably contributes only at high frequencies to the total LE source term, starting from f=2000 Hz for the lower Reynolds numbers and beyond for the higher. The mapping of source terms from the boundary layer resolving LES grid onto the typically coarser preferably uniform APS grid leads to lower high-frequency signal amplitudes for coarser APS mesh size in regions with small turbulent structures. The impact of this amplitude reduction on the predicted acoustics sound power levels was still very small, exhibiting relative differences less than 0.7% for the different APS meshes. Despite the LES-specific limitations expected from the decrease of directly resolved content for higher Reynolds numbers, the use of increasingly underresolved source terms did not significantly lower the accuracy of finally predicted acoustics. The comparison of the acoustic results against data from dedicated measurements generally showed very good agreement for all Reynolds numbers.