Shape Of Pipe Research Articles

Explosion Characteristics of Hydrogen Gas in Varying Ship Ventilation Tunnel Geometries: An Experimental Study

Hydrogen is widely regarded as a key element of prospective energy solutions for alleviating environmental emission problems. However, hydrogen is classified as a high-risk gas because of its wide explosive range, high overpressure, low ignition energy, and fast flame propagation speed compared with those of hydrocarbon-based gases. In addition, deflagration can develop into detonation in ventilation or explosion guide tunnels if explosion overpressure occurs, leading to the explosion of all combustible gases. However, quantitative evidence of an increase in the explosion overpressure of ventilation tunnels is unavailable because the explosive characteristics of hydrogen gas are insufficiently understood. Therefore, this study investigated an explosion chamber with the shape of a ventilation pipe in a ship compartment. The effect of tunnel length on explosion overpressure was examined experimentally. For quantitative verification, the size of the hydrogen gas explosion overpressure was analyzed and compared with experimental values of hydrocarbon-based combustible gases (butane and LPG (propane 98%)). The experimental database can be used for explosion risk analyses of ships when designing ventilation holes and piping systems and developing new safety guidelines for hydrogen carriers and hydrogen-fueled ships.

Effect of Microstructure and Tensile Shear Load Characteristics Evaluated by Process Parameters in Friction Stir Lap Welding of Aluminum-Steel with Pipe Shapes

In recent years, friction stir welding (FSW) of dissimilar materials has become an important issue in lightweight and eco-friendly bonding technology. Although weight reduction of low-rigidity parts has been achieved, the weight reduction has been minimal because high-rigidity parts such as chassis require the use of iron. Considering the difficulty of welding a pipe shape, it is necessary to understand the effect of process parameters on mechanical performance. As a result of the study by various process parameters affecting the joint between aluminum and steel in the shape of a pipe, it can be seen that the tool penetration depth (TPD) has the most important effect on the tensile shear load (TSL). However, the effect of TPD on intermetallic compound (IMC), which has the most important influence on fracture, has not been well established. In this study, the effect of process parameters on IMC thickness and TSL in FSW of A357 cast aluminum and FB590 high tensile steel was investigated to reduce the weight of the torsion beam shaft of an automobile chassis. After the FSWed experiment, measurements were performed using an optical microscope and scanning electron microscopy (SEM) to investigate the microstructure of the weld. The formation of an IMC layer was observed at the interlayer between aluminum and steel. TPD is a major factor in IMC thickness variation, and there is a direct relationship between IMC thickness reduction and TSL increase, except for certain sections where the welding speed (WS) effect is large. Therefore, in order to improve mechanical properties in friction stir lap welding of aluminum and steel for high-rigidity parts, it is necessary to deepen the TPD at a level where flow is dominant rather than heat input.

Vertical Fiberglass Micropiles as Soil-Reinforcing Elements.

This article is dedicated to developing a ground improvement technique using vertically oriented reinforcement elements prefabricated utilizing fiberglass pultruded pipe and helical shape wideners at the bottom toe. Structures of the prefabricated helical micropiles varied by the length and cross-section area introduced into the soil massive as reinforcing bearing elements. The effect of the reinforcements geometry variation was investigated through a reinforcement factor (µ), based on which a calculation method for measuring settlement of reinforced soil has been previously developed Full-scale field plate load tests were performed before and after reinforcing the soil to investigate the changes in the soil stiffness after the reinforcement process. Comparative analysis between the reinforced and reference soft sandy soil indicates an average increase in the deformation properties of the fiber reinforced soils by 8%, 30%, 63% at the applied pressures of 100, 300, and 550 kPa, respectively. The influence of the fiber reinforced polymers (FRP) geometrical properties on the final composite settlement was determined. A comparative analysis of the calculated and the actual plate load tests results reveals that the previously proposed settlement calculation method is adequate for further development.

Analysis of the change in the shape of large diameter pipes during assembly and welding

Studies have been carried out to assess the effect of residual stresses and deformations arising in the process of assembly and welding, as well as after metal cooling, on the shape of pipes. In the process of cooling, the weld and heat-affected sections are shortened, leading to a curvature of their generatrices, with the main change noted at the ends of pipes. To determine the stresses and strains in pipes, experimental and analytical studies and mathematical modeling were carried out at the assembly and welding site. Presented are the results of geometry measurements from the front and rear ends of pipe blanks and pipes with dimensions of 1420×25; 1420×21.6; 1420×18.7; 1420×15.7 mm of K60 strength class and 813×39; 813×37.4 and 813×39 mm of K65 strength class after step forming, assembly, welding and expansion, as well as the curvature of these pipes. The calculation of stress intensity along the entire perimeter of pipes 813×39 and 1420×25.8 mm before and after assembly on the assembly and welding mill was carried out. Pipes with a ratio of diameter to wall thickness of 90.4 of the K60 strength class had the largest deviation in ovality and curvature, and the smallest deviations were 20.8 and 22.3 of the K65 strength class. After welding of the external seams, the vertical diameter and the value of curvature increase, and after expansion they decrease. The total change in the ovality of pipes due to residual welding deformations is on average 0.5% for pipes with a diameter of 813 mm and 2% for pipes with a diameter of 1420 mm.

Impedance reduction by a SiC-loaded flange and its application to the J-PARC main ring septum magnet

The beam power of the main ring of the Japan Proton Accelerator Research Complex (J-PARC) is currently being increased. For high-power beam realization, it is essential to suppress the beam instability that limits the beam power and to estimate and enact countermeasures against the beam coupling impedance of individual devices, which can affect the collective motion of the beam. Therefore, we promote the identification and the reduction of impedance. The fast-extraction (FX) septum magnet will be replaced with another magnet that copes with higher numbers of repetition cycles. Despite their different structures, both septa demonstrated a large impedance in estimates performed by the CST studio suite wake-field solver. As the new septum magnet has been completely manufactured, we considered reducing its impedance by installing additional components. These components must meet strict installation requirements: they must be easy to install on the septum magnet, must not protrude into the beam pipe connected to the septum magnet (to avoid interfering with maintenance), must not disturb the wide horizontal aperture of the septum magnet, and must not affect the magnetic field. The widely used taper impedance-reduction method would be effective but violates the second requirement above (i.e., protrusion into the beam pipe). We found that by attaching a copper plate and SiC to the flange of the septum magnet, we could effectively reduce the impedance while satisfying all installation requirements. The copper plate on the flange reduces the impedance below the cut-off frequency. Moreover, when SiC was loaded, the remaining impedance was three times lower than when using the copper plate alone. After applying this method to the new septum magnet, the maximum longitudinal impedance was reduced to 1% of the value without countermeasures, largely improving the beam stability condition. We also estimated the required thickness of SiC and the calorific value. This method saves space and is installed by simple attachment to the flange, regardless of the shape of the beam pipe. Therefore, it is also applicable to other devices.

Research concerning the influences related to the perforated hole diameters in long pipes

The purpose of this paper is to highlight the influence of the dimensional characteristics and mechanical strength characteristics of the pipe material on the diameter of the perforated holes in these long pipes, to maintain the stability of the pipe shape in the perforated area. The research aimed to establish the maximum limit dimensions of holes that can be made in long round pipes with thin walls, through perforating by cold plastic deformation in air, using only a punch applied to on the outside of the pipe, for a particular case of pipe clamping. Following the research, the mathematical relations between the maximum diameters of the holes that can be obtained in round pipes, in correlation with the dimensional characteristics and the mechanical resistance of the material, are presented. The characteristics taken into account are the outer diameter of the pipes, the thickness of the pipe wall, and the permissible resistance to rupture of the part material. In the conclusions, it is specified that the determined mathematical relations allow the construction of variation diagrams and the determination of the maximum possible diameters, for other dimensional characteristics of pipes and for other mechanical strength characteristics of different materials.

Investigation of approximate mode shape and transition velocity of pipe conveying fluid in failure analysis

Structures dynamic characteristics and their responses can change due to variations in system parameters. With modal characteristics of the structures, their dynamic responses can be identified. Mode shape remains vital in dynamic analysis of the structures. It can be utilized in failure analysis, and the dynamic interaction between structures and their supports to circumvent abrupt failure. Conversely, unlike empty pipes, the mode shapes for pipes conveying fluid are tough to obtain due to the intricacy of the eigenvectors. Unfortunately, fluid pipes can be found in practice in various engineering applications. Thus, due to their global functions, their dynamic and failure analyses are necessary for monitoring their reliability to avert catastrophic failures. In this work, three techniques for obtaining approximate mode shapes (AMSs) of composite pipes conveying fluid, their transition velocity and relevance in failure analysis were investigated. Hamilton’s principle was employed to model the pipe and discretized using the wavelet-based finite element method. The complex modal characteristics of the composite pipe conveying fluid were obtained by solving the generalized eigenvalue problem and the mode shapes needed for failure analysis were computed. The proposed methods were validated, applied to failure analysis, and some vital results were presented to highlight their effectiveness.

히트 파이프 형상이 열전달 성능에 미치는 영향

In this study, the effect of the shape of the heat pipe on heat transfer performance was evaluated using experimental and simulation approaches. The volume fraction of the working fluid was set to 10-30% in the annular heat pipe, and the amount of heat rate of 10-30 W was applied until the temperature reached a steady state. The experimental results show similar temperature distribution at the points not in contact with the heat source regardless of the volume fraction. The overall temperature distribution also increases as the amount of heat input increases. This study reveals that the heat pipe could obtain high performance by appropriately combining the volume fraction of working fluid and heat input. Based on these experimental data, heat transfer performance was investigated with two different heat pipes models. The heat transfer performance of a heat pipe can be affected by vapor flow, evaporation, and condensation. The steam is easier to flow in the annular heat pipe that shows better heat transfer performance than a square column type heat pipe.

Discrete curvature-based shape configuration of composite pipes for local buckling detection based on fiber Bragg grating sensors

For the high strength, good corrosion resistance and stability, carbon fiber reinforced polymer (CFRP) composites can be made into pipes to transfer gasses and oils in submarine environment. Structural performance and shape of CFRP composite pipes are particularly important to sustain the regular operation of the delivery system. To obtain the in-field shape and identify the local buckling of CFRP composite pipes, quasi-distributed optical fiber sensing techniques have been developed based on the multiplex of fiber Bragg grating (FBG) sensors. Theoretical investigation on shape profile configuration of the pipes based on the measured strains has been performed. Relationship between the accuracy of configuration algorithm and the sensor layout has also been explored. Experiments have been conducted to check the effectiveness and accuracy of the proposed sensing technique and curve configuration algorithm. Results validate good measurement performance of the proposed sensors and high accuracy of the shape-configuration algorithm. Suggestions on the sensor layout of long-distance pipe structures are provided with the comprehensive consideration of overall structural shape control and economical factor. The study can be adopted to instruct the establishment of the structural health monitoring system, identify the buckling and assess the safety operation of pipe structures.

CFD investigation of internal elbow pipe flows in laminar regime

Elbow pipes are crucial parts of many fluid transport systems in the oil and gas industry. The curved shape of such pipes induces centrifugal forces on the internal flow, ultimately affecting the flow velocity and creating pressure differences within the elbow. The present study aims to investigate the effects of the curvature ratio of an elbow pipe on the internal pipe flow using three-dimensional numerical simulations. For laminar flows, the simulations are based on four Reynolds numbers ranging from 200 to 2000 and three curvature ratios of Ro=5.6, 11.2 and 22.4. A mesh convergence study is carried out for 3 meshes with increasing resolution. The results based on the optimal mesh is then compared with the published experimental and numerical results for validation. Once the validation is confirmed, further simulation and analysis are performed for each combination of curvature ratio and Reynolds number. The results reveal that there is flow separation due to the centrifugal forces induced by the curved shape. It is also shown that secondary flows consisting of symmetrical helical vortices called Dean vortices are generated. The intensity of this secondary flow is shown to increase with the increasing Dean number.

The Corrosion Performance of Aluminized Steel with Coating Defects Exposed to Natural Waters

Aluminized steel is a common material used in the production of corrugated drainage pipes that are used to allow water flow under roads and sidewalks. During fabrication, hot-dipped aluminized steel sheets are mechanically formed into a cylindrical pipe shape in which metal dyes or rollers are used to form the corrugations to increase structural capacity. Additionally, the edges of the sheets are linked together in an interlocking fashion to provide a sturdy seam. The plastic deformation of aluminized steel results in coating deficiencies which has been shown to result in premature corrosion of the substrate steel. Depending on the exposure conditions, the service life of the pipes may be significantly reduced.The objective of this work is to determine the corrosion performance at coating deficiencies generated within the lock seams of aluminized steel drainage pipes. Previous work addressing the corrosion of aluminized steel has primarily focused on the cut edge where the ratios of coating to substrate material is minimal. This work presents experimental results of long-term exposure studies with detailed analysis of corrosion morphology as well as local galvanic activity distributions at defect locations using the scanning vibrating electrode technique (SVET). Additionally, crevice corrosion cells are set up to monitor corrosion activity within small gaps indicative of the space within the lock seams. Results are compared between artificially defected and as-received cases for mild and aggressive solutions of simulated natural water. A finite element model capable of simulating the corrosion progression for various lock seam geometries and exposure conditions will also be presented.

A Mixed Flow Analysis of Sewer Pipes with Different Shapes Using a Non-Oscillatory Two-Component Pressure Approach (TPA)

This paper aimed to justify the performance of a non-oscillatory TPA-based model proposed by the authors for capturing transient mix flow in sewer systems consisting of a variety of pipe shapes. The model utilizes a first-order Godunov Finite volume numerical scheme in which a Harten–Lax–van Leer (HLL) Riemann solver was used for calculating the fluxes at the cells’ boundaries. The spurious numerical solution associated with the transient mix flow analysis is suppressed by enhancing the numerical viscosity of the scheme when the pipe pressurization is imminent. Due to the lack of experimental data for systems with pipe shapes other than circular and rectangular, a hypothetical pipe system for which analytical solutions exist was employed to verify the model performance. The results reveal that for all pipe shapes considered, the model provides oscillation-free solutions even at a high acoustic speed of 1400 m/s. It is also observed that the numerical results are in perfect agreement with the analytical solution. The obtained results conclude that the proposed model can be utilized to capture transient responses of sewer systems with any pipe shape.

Effect of Process Factors on Tensile Shear Load Using the Definitive Screening Design in Friction Stir Lap Welding of Aluminum–Steel with a Pipe Shape

Recently, friction stir welding of dissimilar materials has emerged as one of the most significant issues in lightweight, eco-friendly bonding technology. In this study, we welded the torsion beam shaft—an automobile chassis component—with cast aluminum to lighten it. The study rapidly and economically investigated the effects of friction stir welding and process parameters for A357 cast aluminum and FB590 high-strength steel; 14 decomposition experiments were conducted using a definitive screening design that could simultaneously determine the effects of multiple factors. Friction stir welding experiments were conducted using an optical microscope to investigate the tensile shear load behavior in the welding zone. In addition to understanding the interactions between tool penetration depth and plunge speed and tool penetration depth and dwell time, we investigated and found that tool penetration depth positively affected the size of the hooking area and contributed to the stabilization and size reduction of the cavity. The experimental results showed that the plunge depth and tool penetration depth effects were most important; in this case, the plunge depth negatively affected the magnitude of tensile shear load, whereas the tool penetration depth had a positive effect. Therefore, when selecting a tool, it is important to consider the plunge depth and tool penetration depth in lap welding.

Simulation of Non-Spherical Rice Seed Motion in Pneumatic Conveying with Bend by CFD-DEM

The rice flow characteristics in pneumatic conveying determined the performance of pneumatic metering device for rice seed. The non-spherical rice seed motion in pneumatic conveying with bend was investigated by CFD-DEM simulation. The rice seed particle model was established by multi-sphere method, and a typical pneumatic conveying horizontal-vertical pipe with bend was selected. The applicability of three drag force models on non-spherical particle was compared. The particle flow characteristics in different pipes including the vertical-horizontal pipe and the horizontal-horizontal pipe were investigated. The non-spherical particle formed a particle rope at the outlet of bend, and the particle rope dispersed at downstream of the vertical pipe. The effect of particle shape on gas-solid flow characteristics was obtained. The gas velocity value in the bend for non-spherical rice particle was higher than that for spherical particle. The non-spherical rice particle rope dispersed more slowly than the spherical particle rope. The particle velocity profile of non-spherical and spherical particles was similar. The differences of the gas-solid flow predicted by Free stream model, Ergun and Wen & Yu model, and De Filice model were limited. The particle rope can also be formed in vertical-horizontal pipe and horizontal-horizontal pipe, but its dispersion represented different features. The results showed that particle shape and structure of pipe can influence the gas-solid flow characteristics, and a suitable particle model was important for the gas-solid flow simulation by CFD-DEM.

Combining a statistical model with machine learning to predict groundwater flooding (or infiltration) into sewer networks

Groundwater flooding (or infiltration) in sewer systems leads to significant negative consequences such as discharge of untreated sewage, reduction of system capacity, structural deterioration, and dilution of the wastewater stream delivered to a treatment plant causing malfunction. Cities with aging networks along coastal areas, where aquifers are shallow, are particularly vulnerable. Rehabilitation is necessary to mitigate the negative impact of infiltration but costly. Therefore, a prioritization strategy of intervention is required. This paper presents a decision-support model to identify the probability of infiltration into aging sewer when observations of infiltration and sewer conditions are sparse and time-limited. The model is based on logistic regression, where the variables are: material, soil, water table, and pipe size and shape. As a proof-of-concept, the method was applied to the city of Hoboken, NJ. Machine learning was used to calibrate, validate, and test the model using infiltration measurements, provided by the water authority. Upon calibration, model predictions agree well with the measurements with an accuracy of 82%. Sensitivity analysis of the model was carried out and shows that the most important parameter is the water table of the shallow aquifer. Overall, the proposed approach can be a valuable tool for strategic intervention of sewer repair and flood mitigation in urban areas.

Seismic features and origin of fluid escape pipes offshore Hainan Island on the northern slope of South China Sea

Fluid escape pipes form when subsurface fluids flow upwards. Various factors can lead to their occurrences. Here we present an example offshore Hainan Island in the northern South China Sea (SCS) where buried mass transport deposits (MTDs) played an important role in the formation of fluid escape pipes. Based on a three dimensional (3D) seismic reflection dataset, more than 120 seismic pipes seemed to be distributed irregularly in the shallow 230 m sequences over an area of 150 km2. The pipe field seats on a gentle slope segment that is nipped by steep and rugged slope where abundant seabed MTDs exist. The pipes can be divided into two types; ones terminate upward at the seabed with pockmarks and the others have upper extremes vanishing at levels 20–85 m below the seabed. Pipes are deduced to form due to escapes of overpressured fluid indicated by stacked high amplitude reflections (HARs) at lower part of pipes and below pipes. MTDs are observed to have a well correspondence with buried MTDs, and their couples are grouped into four relatively independent regions that are separated by normal sequences. It is suggested that these buried MTDs triggered the release of overpressured fluid due to differential compaction between MTDs bodies and overlying/lateral sediment. Buried MTDs eventually determined the spatial distribution, shape, and scale of fluid escape pipes. Selective occurrences of pipes on the gentle slope rather than the steep slope depended on the sedimentary setting, in which the undisturbed clinoform was well developed overlying widespread MTDs in late Quaternary on the gentle slope, but was absent on the steep slope. This leaded to a process of rapid deposition to favor the formation of overpressured fluid compartment at/near pipe roots on the gentle slope. Moreover, this work provided significant results for the oil company to avoid the pipeline route crossing the pipe field, even if it has a gentler terrain.

Performance of a full-scale energy pile for underground solar energy storage

This study presents a field test to investigate the thermal injection performance of a full-scale energy pile for underground solar energy storage (USES). The tested energy comprises a full-scale bridge pile foundation and a spiral-shaped pipe. Numerical modeling was carried out to provide complementary results. Sensitivity analyses of the pipe configuration and operation mode on the thermal injection performance of the energy pile were performed based on the numerical modeling. The results showed that 84% of the injected thermal energy could be transferred to the surrounding soil by the energy pile, and the total amount of the thermal energy stored by a single energy pile was −3.2 GJ over 29.5 days. The maximum average value of the thermal injection rate of the energy pile was equal to −129 W/m, which was 2–3 times larger than the thermal injection rate of the geothermal boreholes. Compared to the continuous USES operation of the energy pile, the intermittent mode of the energy pile was more efficient for USES. Increasing the length of the heat exchange pipe of the energy pile was more effective in enhancing the thermal injection performance of the energy pile for USES than changing the pipe shape.

Output power boosting of a photovoltaic panel based on various back pipe structures: a computational study

The efficiency of photovoltaic panels (PV) drops due to the rise in temperature, which leads to a decrease in the PV output power. A PV/Thermal system is therefore used as a solution to increase the output power from the PV panels. Comsol Multiphysics software program, a simulator-based Finite Element Method (FEM) tool, and Matlab program simulations are used to perform this electro-thermal model. The simulation process for different back pipes follows a serpentine, and a new shape of pipes called (square shapes) which are attached under the PV module. These shapes were specifically chosen for higher conversion efficiency and increase the heat transfer of the system. Additionally, a comparison between electrical parameters and heat transfer characteristics of water and CuO/water nanofluid in a PV cooling system has been studied. The new shape leads to improve the photovoltaic (PV) module parameters, such as short circuit current ISC, open-circuit voltage VOC, and maximum power Pmax for a new shape more than the serpentine shape. These parameters are calculated under Air Mass 1.5 G (AM1.5G) with 1000 W/m2 of irradiance which is considered the average irradiance at the MENA (The Middle East and North Africa) region throughout the year. The results exhibit the PV module’s total enhancement by using the new shape with CuO nano-fluid about 24.7 %.

Shape from apparent contours for bent pipes with constant diameter under perspective projection

In perspective projection images, apparent contours are important bases for recovering the three-dimensional (3D) shapes of constant diameter pipes (CDP). In order to complete the 3D reconstruction of CDP under perspective projection, this article first analyzes the single-view perspective projection model of CDP in detail. On this basis, coupled point pairs searching and projected axis extraction methods based on two facing apparent contours are proposed. After that, stereo vision technology is adopted to realize the 3D reconstruction of axis and the measurement of radius. Finally, the experiments with both synthetic and real data show that the proposed method has higher CDP reconstruction accuracy compared with the conventional method processed under orthogonal projection.

Thermal and Flow Simulation of Concentric Annular Heat Pipe with Symmetric or Asymmetric Condenser

The current research work describes the flow and thermal analysis inside the circular flow region of an annular heat pipe with a working fluid, using computational fluid dynamics (CFD) simulation. A two-phase flow involving simultaneous evaporation and condensation phenomena in a concentric annular heat pipe (CAHP) is modeled. To simulate the interaction between these phases, the volume of fluid (VOF) technique is used. The temperature profile predicted using computational fluid dynamics (CFD) in the CAHP was compared with previously obtained experimental results. Two-dimensional and three-dimensional simulations were carried out, in order to verify the usefulness of 3D modeling. Our goal was to compute the flow characteristics, temperature distribution, and velocity field inside the CAHP. Depending on the shape of the annular heat pipe, the thermal performance can be improved through the optimal design of components, such as the inner width of the annular heat pipe, the location of the condensation part, and the amount of working fluid. To evaluate the thermal performance of a CAHP, a numerical simulation of a 50 mm long stainless steel CAHP (1.1 and 1.3 in diameter ratio and fixed inner tube diameter (78 mm)) was done, which was identical to the experimental system. In the simulated analysis results, similar results to the experiment were obtained, and it was confirmed that the heat dissipation was higher than that of the existing conventional heat pipe, where the heat transfer performance was improved when the asymmetric area was cooled. Moreover, the simulation results were validated using the experimental results. The 3-D simulation shows good agreement with the experimental results to a reasonable degree.