Pipe Expansion Research Articles

Analytical relations for fields and currents in magnetic-pulsed «expansion» of tubular conductors of small diameter

Introduction. This work was initiated by the problems of cardiovascular diseases, which are one of the main causes of mortality of the population of our planet. More than ten years ago, in 2012, approximately 3.7 million people died of acute coronary syndrome worldwide. The fight against such pathologies is carried out with the help of so-called stents, the manufacture of which can be carried out by the method of magnetic pulse «expansion» from hollow metal cylinders. The limited production possibilities of magnetic pulse «expansion» were caused by the minimum cross-sectional size of the inductor-instrument, which can be practically manufactured. Other tools are required to perform this operation. Novelty. A system of magnetic-pulse expansion of thin-walled pipes of small diameter with an inductor that excites an azimuthal electromagnetic field in the case of direct current passing through the processing object and in the absence of its connection in an electric circuit with an inductor is proposed. Purpose. The main analytical dependencies for the characteristics of the electromagnetic processes taking place in the inductor systems for the expansion of cylindrical conductive pipes of small diameter when direct passage of current through the processed object and when it is not connected to an electric circuit with an inductor (insulated billet) is derived. Methods. The solution of the boundary value problem with given boundary conditions was carried out by applying Laplace transforms and integrating Maxwell’s equations. Results. Analytical expressions were obtained for the main characteristics of the processes: the intensities of the excited electromagnetic fields and currents in the system depending on the parameters of the studied systems. The analysis of possible technical schemes for solving the given problem indicated the choice of the optimal variant of an effective system of magnetic-pulse «stretching» of thin-walled cylindrical conductors of small diameter. Practical value. Based on the qualitative analysis of the obtained results, recommendations for the practical implementation of the proposed system were formulated. The obtained dependences allow us to give numerical estimates of the effectiveness of excitation of magnetic pressure forces on the object of processing and to choose directions for further improvement of the magnetic pulse technology for solving such problems. References 23, figures 2.

Effect of particle diameter and void fraction on gas–solid two-phase flow: a numerical investigation using the Eulerian–Eulerian approach

AbstractSudden expansion pipes are crucial in fluid dynamics for studying flow behavior, turbulence, and pressure distribution in various systems. This study focuses on investigating the behavior of a two-phase flow, specifically a gas–solid turbulent flow, in a sudden expansion. The Eulerian–Eulerian approach is employed to model the flow characteristics. The Eulerian–Eulerian approach treats both phases (gas and solid) as separate continua, and their interactions are described using conservation equations for mass, momentum, and energy. The study aims to understand the complex phenomena occurring in the flow, such as particle dispersion, turbulence modulation, and pressure drop. The governing equations are solved using house developed code called FORTRAN, a widely used programming language in scientific and engineering simulations. The results of this study will provide valuable insights into the behavior of gas–solid two-phase flows in sudden expansions, which have important applications in various industries, including chemical engineering, energy systems, and environmental engineering. A parametric study of the impact of particles diameters (20, 120, 220, 500 µm), the solid volume loading ratios $$(0.005, 0.008, 0.01)$$ ( 0.005 , 0.008 , 0.01 ) and area ratios (2.25, 5.76, 9) effect of sudden expansion on the streamlines, local skin friction, pressure, velocity, turbulent kinetic energy, and separation zone.

Pelayanan pengujian kekuatan pipa HDPE di Laboratorium Kimia Material Departemen Teknik Material dan Metalurgi FTIRS-ITS

HDPE pipes are widely used in various industries, such as drinking water and sewage infrastructure, petroleum, agriculture, and construction. The advantages of HDPE pipes include corrosion resistance, light weight, easy installation, and low maintenance costs. Checking the quality of HDPE pipes, spesifically from industry that we tested, is important to ensure infrastructure safety, prevent system failure, improve operational efficiency, obtain user satisfaction, and conserve resources. We evaluated HDPE pipes with type PN 12.5 SDR 13.6 from industry in terms of resistance to hydrostatic pressure, tensile strength, and expansion capability. The evaluation was carried out at the Material Chemistry Laboratory of the Department of Material Engineering and Metallurgy FTIRS-ITS ITS in accordance with the standards of SNI 4829.2: 2015, ASTM D 638 M, and SNI 2553: 1999. The results show that HDPE pipes can withstand hydrostatic pressure up to 12 bar without leakage. The average tensile strength is 43.34 MPa with an average elongation of 354%, indicating ductile pipe properties with necking. Pipe expansion was observed to be 0.195%, indicating a good ability of the pipe to undergo expansion.

Predicting reattaching turbulent gas-solid flow with a strong pressure gradient

In this study, the focus is on examining how the flow characteristics are influenced by particle density in the context of downward turbulent gas-solid flow through a sudden expansion pipe. The Eulerian-Lagrangian approach is performed to simulate the gas and the solid phases. A self-written FORTRAN code is developed based on the finite volume technique with a hybrid scheme in a staggered grid to simulate the problem. Experimental measurements and numerical simulations are employed to study the flow dynamics. After comparing the outcomes with previously published experimental findings, the current code demonstrates favorable results that provide encouragement for the authors to expand their theoretical work and explore various parameters. The sudden expansion performance is studied at different particle materials (sodium, sand, aluminum, copper, and gold) and Reynolds numbers. In light of the computational results, the particle material has a significant influence on the flow behavior. As the particle density increases from sodium to gold, the solid phase becomes more concentrated and exhibits different flow patterns. The particle density also affects the pressure distribution, velocity profiles, and turbulent kinetic energy in the flow. The particle size significantly influences both the flow behavior and the loss coefficient.

Annular expansion for enhanced orientation and mechanical properties of extruded amorphous PPESK/PES pipes

AbstractWith the discovery of deeper oil fields, conventional metal pumping pipes have been proven to be ineffective in meeting the requirements for deep well oil production due to their high weights and limited corrosion resistance. Therefore, in this study, a composite of Poly(phthalazinone ether sulfone ketone) (PPESK) and polyethersulfone (PES) was used to fabricate nonmetal pipes. To enhance the mechanical properties of the PPESK/PES pipes, a self‐designed annular expansion pipe extruder head was used. The circumferential burst stress and axial tensile strength of the PPESK/PES pipes subjected to 30° expansion were 73.0% and 48.9% higher than those of the unexpanded sample, respectively. When annular expansion was integrated into the extrusion of PPESK/PES/carbon fiber pipes, the axial tensile strength and circumferential burst stress were 45.9% and 88.8% higher than those of the unexpanded sample, respectively. Results of polarized infrared testing and metallographic microscopic examinations demonstrated that molecular chains present a regular orientation at a certain angle to the extrusion direction, under the effect of annular expansion extrusion. These findings highlight the efficiency of annular expansion in promoting the large‐scale production of pipes.

Characteristics of Coal Dust Deposition in Boiler Tail Gas Pipelines

Coal dust deposition in boiler tail gas pipelines can significantly affect boilers’ thermal and energy efficiency. This study investigates the deposition characteristics of coal dust particles in boiler tail gas tubes in variable cross-section tubes. Numerical simulations were performed using the Reynolds Stress Model and the Discrete Particle Model. User-defined functions coding is used to construct the particle deposition model in the particle deposition model. The study analyses the distribution of turbulent kinetic energy locations in the gradient tube, compares the distribution of particle deposition on its wall, and concludes that the deposition distribution of coal dust particles in the gradient tube is slightly different for different particle sizes. Smaller particles have a higher deposition efficiency in equal cross-section pipes than larger particles. Particle size also has a significant effect on pipe taper and expansion. The results of this study can provide theoretical guidance for optimising the design of boiler tail gas pipelines, improving energy efficiency, and reducing environmental pollution.

Characteristics of Coal Dust Deposition in Boiler Tail Gas Pipelines

Coal dust deposition in boiler tail gas pipelines can significantly affect boilers’ thermal and energy efficiency. This study investigates the deposition characteristics of coal dust particles in boiler tail gas tubes in variable cross-section tubes. Numerical simulations were performed using the Reynolds Stress Model and the Discrete Particle Model. User-defined functions coding is used to construct the particle deposition model in the particle deposition model. The study analyses the distribution of turbulent kinetic energy locations in the gradient tube, compares the distribution of particle deposition on its wall, and concludes that the deposition distribution of coal dust particles in the gradient tube is slightly different for different particle sizes. Smaller particles have a higher deposition efficiency in equal cross-section pipes than larger particles. Particle size also has a significant effect on pipe taper and expansion. The results of this study can provide theoretical guidance for optimising the design of boiler tail gas pipelines, improving energy efficiency, and reducing environmental pollution.

Justifying the parameters of compensation of temperature extensions of heat network pipelines

Problem. Influence of temperature of editing and material of leading pipe of the preliminary isolated hot-water system is set on the size of distance between non-permanent scrays and rule-making in relation to determination of size of maximal distance of placing of scrays on the hot-water system, that determination of their necessary amount. Goal. The purpose of the work is to study the influence of the installation temperature and the material of the conductive pipe of the pre-insulated heat pipe on the distance between the disposable compensators of the temperature elongation of the heat pipe. Method. Preliminary stretching of the heat pipe can be done mechanically or thermally. Since mechanical stretching for the construction of pre-insulated pipelines is very difficult to perform (although it is done), so-called thermal stretching is used in practice - preheating of pipelines. The essence of this method is that the pipeline is heated to an average temperature between the installation temperature and the maximum operating temperature of the heat carrier before it is backfilled. Results. An increase in the distance between one-time compensators for thermal expansion of the heat pipe (reduction in their number) is possible under the conditions of an increase in the temperature of the heat network installation (calculations showed that when the installation temperature changes from 0 °С to +20 °С, the maximum distance between compensators increases by 2.33 times (instead of 10.3 m, received 24 m), therefore the required number of compensators will decrease). Scientific novelty. The influence of the installation temperature and the material of the conductive pipe of the pre-insulated heat pipe on the distance between disposable compensators has been established, and recommendations have been made for determining the maximum distance of placing compensators on the heat pipe, that is, determining their required number. Practical significance. The use of steels with higher values of allowable stresses (calculations showed that replacing St.10 steel with an alloyed one, with an increase in allowable stresses by 1.42 times, increases the maximum distance between disposable compensators by 5.1 times, which also significantly reduces their number on the heat pipe).

Comparative investigation on high-pressure flow accelerated corrosion at gradual contraction and gradual expansion pipes

In current study, the flow accelerated corrosion behaviors of X65 steel gradual contraction and gradual expansion pipes under high-pressure conditions were comparatively investigated by establishing dynamic in situ electrochemical tests under high CO2 partial pressure conditions in a loop apparatus. The findings indicate that the corrosion rate is reduced along the flowing direction of gradual contraction pipe. Nevertheless, the corrosion rate firstly descends and subsequently ascends along the flowing direction of gradual expansion pipe, and the lowest corrosion rate is presented in inclination segment close to the straight pipe with large diameter. The corrosion rate at the top wall of gradual contraction pipe is symmetrical to that at the bottom wall, while it is asymmetrically distributed at the top wall and the bottom wall of inclination segment in gradual expansion pipe. The distribution of corrosion rate is correlated with the flow fields at gradual contraction and gradual expansion pipes. Furthermore, the special corrosion rate distribution at inclination segment of gradual expansion pipe is ascribed to the formation of secondary flow and vortexes.

Load Transferring Characteristics of Expanded Pile with Cement Mortar Mixture for Pipe Pile

Two kinds of interface shear force transmission models of expanded pile are introduced in combination with FRIC subroutine. ABAQUS is used to carry out numerical analysis to study the load transfer characteristics of expanded pile under vertical load. The results show: the load on the top of the pile is transmitted by the strong cohesive force between the pipe pile and the expanded interface. Under the vertical load, the axial stress of the pipe pile in the expanded pile gradually decreases with the increase of depth, and the axial stress of the expanded part increases first and then decreases with the depth. With the increase of pile length, pipe pile diameter or expansion thickness, the axial stress of pipe pile increases as a whole. With the increase of pile length, the axial stress of the expansion body increases gradually, and with the increase of pile diameter or expansion thickness, the axial stress of the expansion body decreases gradually. The axial stress of the pipe pile in the equal core part of the non-equal core expanded pile gradually decreases with the increase of depth, and the axial stress of the expanded body increases with the increase of the pile length.

Joining of EN AW 6060 Pipes by Plastic Forming

The article deals with an innovative, but not widely used type of joining of aluminum pipes through experiments. The joints are formed by plastic forming. The process is carried out in one step using the principle of pipe expansion, in order to bring the mating surfaces of the two pipes into a suitable position for the subsequent joining, which is created by means of plastic instability and simultaneous pressure flanging. Experimental tests were carried out with the tools designed to create most suitable joints. The length of the plastically formed pipe sections involved in the joint, the angle of the sharpened pipe ends, and the thickness of the formed joints were analyzed. One of the main goals of this study is to determine the proper joining parameters, such as tool distance or edge tapering for further investigations. As per the test results, it can be stated that the technology is suitable for joining aluminum tubes in a cost-effective way, and based on the promising strength results, further investigations will be conducted.

Study on Mechanical Behavior and Deformation Law of Expansion Pro-cess of Expansion Screen Base Pipe

The expansion process of the base pipe of the expanded screen pipe includes large displacement elastic-plastic deformation problems such as geometric nonlinearity, material nonlinearity and contact nonlinearity. In this paper, based on the elastic-plastic deformation mechanism of the base pipe of expanded screen pipe, finite element equations are established and numerical simulation is used to construct a finite element simulation model to study the mechanical behavior and deformation law of Φ203.2 mm base pipe of the expanded screen pipe expansion process. The results show that the expansion rate has no effect on the increase of wall thickness, and the decrease is proportional to the expansion rate. The greater the expansion rate, the greater the residual stress at both ends of the slot.

Study on the burst pressure of support cylinder in expandable liner hanger based on matching between yield strength and fracture toughness

The expandable liner hanger (ELH) is one of the vital completion tools for ultra-deep oil and gas exploration and development. However, the burst pressure prediction of the support cylinder, which is the weak link of ELH, is extremely difficult due to unavoidable severe plastic deformation caused by expansion, which easily causes burst failure of the support cylinder under high temperature and high pressure with corrosive media, and poses a threat to wellbore integrity. Research shows that the classic models currently used to calculate the burst pressure of pipeline is mainly established based on yield design criterion and do not consider the effect of complex changes in mechanical properties caused by expansion and plastic deformation on burst pressure, especially the sharp decrease in fracture toughness so that they are not suitable for burst pressure prediction of support cylinder in the ELH. Hence, the strength-toughness (S-T) matching criterion used to consider both the burst failure due to the insufficient material strength and the environmental fracture failure due to the insufficient fracture toughness under internal pressure has been presented in this paper, by which the burst pressure model of support cylinder in ELH has been established with due consideration of the complex changes in geometric parameters (such as wall thickness, diameter-thickness ratio, uneven and ovality of wall thickness, manufacturing defects, etc.) and mechanical parameters (hardening exponent, fracture toughness, yield strength, tensile strength, compressive strength, yield-strength ratio, Bauschinger effect, etc.) caused by plastic deformation under different expansion rates by combining elastoplastic theory with fracture mechanics theory. The accuracy and reliability of this burst pressure model have been validated by full-scale burst test data of expansion pipe from the literature. The influences of expansion rate, diameter-thickness ratio, yield-strength ratio, Bauschinger effect, and fracture toughness on the burst pressure of the support cylinder have been obtained, by which the scientific method for improving the bursting pressure of the support cylinder has been formed. Research results could provide an important theoretical basis for predicting and optimizing burst pressure for the support cylinder in the ELH.

Study on explosion characteristics of hydrogen in a sudden expansion pipe

ABSTRACT As a promising green energy source, the risk of hydrogen explosion cannot be ignored. In the industrial environment, the connection between factories and different regions may form a mutated structural space. This structure may have a significant impact on the consequences of hydrogen accidents, which is worthy of study. In this research, the simulation method is used to analyze the explosion and combustion process of hydrogen flame propagation in a sudden expansion pipe, which focuses on the impact of the cross-section ratio. The results indicate that due to the influence of Rayleigh-Taylor instability, the flow field in the dead zone near the sudden expansion structure can be unstable and generate vortices, which will significantly change the development of gas combustion and explosion. Under the extrusion and entrainment of vortices, the flame front structure is changed from finger-like flame to mushroom-like flame. When the flame enters the downstream pipe section through the expansion port, the impact of vortices on the flame propagation velocity is changed from suppression to excitation, and the excitation effect is closely related to the cross-section ratio. At the cross-section ratio μ = 3, the maximum flame propagation velocity and maximum pressure growth rate of the downstream pipe are 198.7 m/s and 53.12 MPa/s, respectively, which are 68.8% and 151.4% times higher than those in the case of the cross-section ratio μ = 1.5. There is a remarkable impact of sudden expansion structure on flame propagation and explosion overpressure.

Study on formability of duplex steel expansion pipe and its threaded joints

The threaded joint of equal well-diameter-expansion pipe is prone to fracture and leakage after expansion forming. The structural integrity and material selection of the expansion pipe threaded joint are the main difficulties. Taking dual-phase steel and other well-diameter expandable casings as the research object, a method combining finite element simulation and experimental verification is used to construct an enhanced constitutive model. Firstly, three kinds of reinforced constitutive models are constructed, and then finite element software is used for simulation, combined with experiments to analyze the axial length of the pipe, pipe wall thickness, thread clearance, material hardness, plastic toughness and microstructure. The results showed that after expansion the top and root of the threaded area of the tube after expansion have greatest change and the residual stress is relatively high. Microhardness and Charpy impact tests were carried out on the pipes before and after expansion to study the changes in hardness and toughness. It can be found that the toughness of the expansion pipe has decreased, and although the wall thickness will be reduced, the strength of the pipe will be significantly increased, which is the effect of work hardening. The topography of the crack surface is nearly identical over the entire range of expansion ratios considered in this study. In addition, the microstructure of the unexpanded and expanded tubes is similar, consisting of ferrite and austenite. This paper provides a theoretical reference for engineering practice.

Investigation on the Influence of Flow Passage Structure on the Performance of Bionic Pumps

The flapping hydrofoil bionic pump drives the hydrofoil to make simple harmonic motion and completes one-way water pumping in the flow passage. As a new pump device that can realize ultra-low head water delivery, the flapping hydrofoil device can effectively enrich the drainage methods of plain rivers and improve water delivery efficiency, and the passage structure is the key factor of ultra-low head devices. In this paper, the two-dimensional flow passage models are established, and the flapping of the airfoil is realized by using the dynamic grid technology. Based on the continuity equation, k-ε turbulence model, and Reynolds time-averaged equation, the flapping hydrofoil device is simulated by transient calculation. The hydraulic performance characteristics of various passages with different widths, such as square passages, micro-arc passages, and convergent–divergent passages, are calculated and simulated. The results show that, under the fixed motion parameters, the narrower the passage width, the higher the outlet velocity, lift, and efficiency of the device, the lower the flow rate. The contraction–expansion pipe can effectively improve the efficiency and flow rate of the device, and, before the wake is stable, the longer the contraction section the better the lifting effect. However, the micro-arc pipeline will affect the formation of a double-row anti-Karman vortex street, resulting in greater energy loss and in its hydraulic performance being inferior to that of the square passage.

Tightening Curves on Surfaces Monotonically with Applications

We prove the first polynomial bound on the number of monotonic homotopy moves required to tighten a collection of closed curves on any compact orientable surface, where the number of crossings in the curve is not allowed to increase at any time during the process. The best known upper bound before was exponential, which can be obtained by combining the algorithm of De Graaf and Schrijver [ J. Comb. Theory Ser. B , 1997] together with an exponential upper bound on the number of possible surface maps. To obtain the new upper bound, we apply tools from hyperbolic geometry, as well as operations in graph drawing algorithms—the cluster and pipe expansions—to the study of curves on surfaces. As corollaries, we present two efficient algorithms for curves and graphs on surfaces. First, we provide a polynomial-time algorithm to convert any given multicurve on a surface into minimal position. Such an algorithm only existed for single closed curves, and it is known that previous techniques do not generalize to the multicurve case. Second, we provide a polynomial-time algorithm to reduce any k -terminal plane graph (and more generally, surface graph) using degree-1 reductions, series-parallel reductions, and Δ Y -transformations for arbitrary integer k . Previous algorithms only existed in the planar setting when k ≤ 4, and all of them rely on extensive case-by-case analysis based on different values of k . Our algorithm makes use of the connection between electrical transformations and homotopy moves and thus solves the problem in a unified fashion.

Modeling of Turbulent Heat-Transfer Augmentation in Gas-Droplet Non-Boiling Flow in Diverging and Converging Axisymmetric Ducts with Sudden Expansion

The effect of positive (adverse) and negative (favorable) longitudinal pressure gradients on the structure and heat transfer of gas-droplet (air and water) flow in axisymmetric duct with sudden expansion are examined. The superimposed pressure gradient has a large influence on the flow structure and heat transfer in a two-phase mist flow in both a confuser and a diffuser. A narrowing of the confuser angle leads to significant suppression of flow turbulence (more than four times that of the gas-drop flow after sudden pipe expansion without a pressure gradient at φ = 0°). Recirculation zone length decreases significantly compared to the gas-droplet flow without a longitudinal pressure gradient (by up to 30%), and the locus of the heat-transfer maximum shifts slightly downstream, and roughly aligns with the reattachment point of the two-phase flow. Growth of the diffuser opening angle leads to additional production of kinetic energy of gas flow turbulence (almost twice as much as gas-droplet flow after a sudden pipe expansion at φ = 0°). The length of the flow recirculating region in the diffuser increases significantly compared to the separated gas-droplet flow without a pressure gradient (φ = 0°), and the location of maximum heat transfer shifts downstream in the diffuser.

Study of the expansion process taking into account the contact interaction of the deforming tool and pipe

The elements of the press expander head and the process of pipes expansion are described. The requirements for pipes before and after expansion in accordance with the standards are given. The methods of research on the section of the hydromechanical expander of the J-C-O-E (TESA) 1420 line are presented. Mathematical modeling is carried out in the DEFORM software package, taking into account prehistory loading. On the basis of the experimental study and numerical analysis, the reasons for the occurrence of deviations from roundness, excess of ovality and the perimeter of pipes before and after expansion are determined. The nature of the distribution of stresses and deformations in the process of eliminating ovality in the contact and non-contact sections of pipes and press expander tools are determined. The most loaded areas during the expansion of thick-walled and thin-walled pipes are revealed, and a method for calculating the deformation force is proposed, taking into account the initial curvature of the deformable shell. A method for expanding pipes is presented, taking into account the uneven distribution of mechanical properties and deviation in geometric parameters, perimeter and length of the pipe.

Dynamic delayed detached-eddy simulation and acoustic analogy analysis of unsteady flow through a sudden expansion pipe

Dynamic delayed detached-eddy simulation and acoustic analogy analysis of unsteady flow through a sudden expansion pipe