Pipe Elements Research Articles

Friction Coefficient Inversion Calculation Based on Quasi - newton Method and Particle Swarm Optimization

Establishing the pipeline network model of oilfield water injection under known partial pressure through fuzzy clustering method. In order to solve the inversion of pipe element friction coefficient in the case that the joint pressure of water injection pipe network is partly known, the simulation mathematical model of network node pressure and the optimal mathematical model of pipe element friction coefficient inversion are established respectively. By combining the simulation of nodal pressure by quasi-newton method and the inversion of friction coefficient by particle swarm optimization, the ideal pipe element friction coefficient of the pipe network with the partly unknown part of the node pressure can be inverted to achieve the partial accurate solution and partial estimation solution of the pipe element friction coefficient.

Single-phase natural circulation in a rectangular loop with a finite capacity heat sink positioned below the heater section

One of the passive safety systems employed in nuclear reactors is a large water pool positioned at an elevation, which acts as a heat sink to remove decay heat from the reactor core in the event of an accident using the natural circulation phenomena. A large mass of water at an elevated position has concerns regarding the safety of support structure, and therefore an alternative methodology where the heat sink is positioned just below the heater section is investigated in this study. Results of an experimental and numerical investigation for the thermal-hydraulic behavior of single-phase natural circulation in a rectangular loop of height 4300 mm and width 1900 mm with the heat sink located at an elevation just below the heater section is reported here. The heat sink was a finite one, a constant volume insulated tank filled with water, whereas the heat source was a constant heat flux type. The loop was constructed with circular pipe elements with a nominal inner diameter equal to 40 mm. The heater section was 1m in height and three input power values equal to 1.15 kW, 1.55 kW, and 2 kW were used in the study. The flow behavior in a single and twin parallel heater system with a single riser was studied. The loop fluid is initially in a single-phase and becomes two-phase as the heat sink temperature rises, but only the results for the loop fluid in the single-phase regime are presented in the current study. The measured mass flow rate, after an initial transient, settles down to values which slowly decreases with time. The average temperature of the heat sink is shown to rise continuously with increasing time, demonstrating the effectiveness of the heat sink in removing the energy input to the working fluid in the heater section. However, the heat sink removes only 60–70% of the input heat while the rest is either lost to the ambient or utilized to raise the enthalpy of the working fluid.The Nusselt numbers in the heater section are also presented which steadily rise after an initial transient. In addition, the values are much higher than those for the corresponding Reynolds number values in forced convection due to the influence of buoyancy-induced convection. The Nusselt number is well correlated by the expression Nu‾=1.35(Ra*‾)0.3 for 2×105≤Ra*‾≤6.5×105and 600≤Re≤1000. Numerical predictions for loop flow rate, temperature variation, and sink temperature using the RELAP5/MOD3.2 code for the experimental configuration of the current study are presented which compare well with the measurements the maximum deviation being less than 10%. Numerical results for pressurizing the working fluid and permitting boiling in the heat sink to drive the system towards steady-state operation are also presented.

Model-driven fault diagnosis of slant cracks in aero-hydraulic straight pipes

A model-driven fault diagnosis method for slant cracks in aero-hydraulic straight pipes is presented in this paper. First, fracture mechanics theory and the principle of strain energy release are used to derive an expression for the local flexibility coefficient of straight pipes with slant cracks. The inverse method of total flexibility is used to calculate the stiffness matrix of straight pipe elements with slant cracks. Second, the Euler-Bernoulli beam model theory is used in conjunction with the finite element method to construct a dynamic model of the cracked pipe. Finally, a contour map method is used to diagnose the slant crack fault and quantitatively determine the crack position and depth. Experimental results show that the proposed method can accurately and effectively identify a slant crack fault in aero-hydraulic pipelines.

Analytical methodology for the verification of buried steel pipelines with flexible joints crossing strike-slip faults

The use of “flexible joints” to enhance the performance of buried pipelines at large PGD areas is a novel design approach with promising results. This paper presents an analytical methodology for the preliminary stress-strain analysis of buried steel pipelines with flexible joints crossing strike-slip faults. The analytical predictions are verified against results from parametric numerical analyses performed with a commercial numerical code. The pipeline is simulated with pipe elements following an elastoplastic material law, while the soil is simulated with non-linear winkler springs. The numerical analyses have been performed for a wide variety of PGD magnitudes, fault crossing angles, flexible joint distance and crossing position. For the sake of simplicity, the mathematics of the new methodology and the verification are presented only for joints with rotation capacity. Μinor modifications required in order to account for the effect of joint extension are stated in the concluding remarks.

Development of synthetic open porous structures for improved heat transfer

If water pipes, which are heated from the outside, are lined with an open porous inner structure, the heat can quickly reach the water via the large contact surface. At the same time, the flow resistance increases due to the presence of the interior. We aim for computationally designing an internal structure that is advantageous for both heat transfer and flow. In this paper we present our path from digital models to metallic pipe components with specifically adjusted properties: First, we design digital models for line pipe elements and qualify them with the help of computer simulations. As a next step, the algorithmically generated samples are printed in 3D. The 3D-printed polylactide models serve as prototypes for the production of metallic pipes, which are then tested in experiments. In this work, three types of inner structures are evaluated: Metal foam, cuboid fins and curved fins. For better comparability, we provide them with almost the same specific surface area and porosity. The use of open-pore metal foams is advantageous for greater heat transfer and fins enable smaller pressure drop.

Automatic arc welding in manufacture and renovation repair of pipe elements of spirals of high-pressure heaters of NPP power units

Automatic arc welding in manufacture and renovation repair of pipe elements of spirals of high-pressure heaters of NPP power units

Автоматичне дугове зварювання при виготовленні та відновлювальному ремонті трубних елементів спіралей ПВТ енергоблоків АЕС

Автоматичне дугове зварювання при виготовленні та відновлювальному ремонті трубних елементів спіралей ПВТ енергоблоків АЕС

Regularities of Changes in the Mechanical Characteristics and Electrical Properties of the Reaction Furnaces Coils Material during Operation

The main causes of early failure of reaction furnaces coils are diffusion processes in the material as a result of which structural changes occur, new phases are formed and void structure is formed in the surface layers of the metal, which has a negative effect on the mechanical characteristics. In this regard as a structurally sensitive method, which allows evaluating the changes occurring in the metal, the response parameters of the electrical signal are used which are sensitive to pore formation and allow predicting the zone of formation of the breaking crack. Fragments of the coils of the reaction furnaces from the radiant section, which were in operation for 750, 1300, 8000, and 10000 hours and the pipe element in the delivery condition were chosen as the objects of the study. As a result of the research a correlation between the amplitude of the first harmonic of the electrical signal output voltage with the results of static tests for tensile and impact bending was established. This happens due to the fact that during operation there is an increase in the relative impact viscosity and relative tensile strength, and the relative magnitude of the voltage amplitude of the first harmonic of the output electrical signal also increases. These results can be used as a method of mechanical properties assessment by non-destructive testing, and also they can be used to develop a criterion for the rejection of reaction furnace coils.

Effect of tantalum on short-term creep of a 12%Cr-3%Co-0.07%Ta martensitic steel for steam blades

9-12%Cr martensitic steels are prospective materials for elements of boilers, tubes, pipes, heaters and steam blades for fossil power plants, which are able to work at ultra-supercritical parameters of steam. Decreasing N content and increasing B content together with increasing Cr content required the optimization of ferrite-stabilizing and austenite-stabilizing elements to avoid the formation of δ-ferrite at high temperatures. Addition of 3-4%Co, 0.01%B, 0.80%Cu and 0.07%Ta as austenite-stabilizing elements can compensate increasing Cr content up to 12% at decreasing N content to 0.003% and provides the δ-ferrite in the amount less than 10%. Two Co-containing 12%Cr steels were developed and investigated. The main difference between these steels is Ta addition; one of the 12%Cr steel studied contains 0.07%Ta, other 12%Cr steel is Ta-free one. Creep tests at 650°C and the applied stresses ranging 180-80 MPa with a step of 20 MPa for both Co-containing 12%Cr steels were carried out. Addition of Ta in the Co-containing 12%Cr steel provide the increment in the creep time to rupture at both high and low applied stresses. This increment in the creep properties due to Ta addition was explained by decrease in coarsening rate of Ta-rich MX carbonitrides during creep at 650°C.

Pressure loss reduction of pipe elements

Abstract A theoretical research was conducted from 2016 to 2018 which aimed to reduce the head loss of pipe networks in the pump stations. The results were promising and predicted an average head loss reduction by 30%. Afterwards, physical experiments were carried out to test the effectiveness of the new pipe designs. Two new prototype pipe sections were installed into one of our pump stations. The experiment was successful as two unique pipe sections installed in the discharge pipe reduced the head loss of the pump station by 25–26%. According to these results, we can set a target value of 30% head loss reduction at full pump station pipe reconstruction.

Parametric solution of lateral buckling of submarine pipelines

Lateral buckling analysis of on-bottom submarine pipelines is of particular interest in the offshore industry due to the complexities involved in the analysis, and the potential design efficiencies that can be unlocked. Classical buckling theories by previous researchers and recent joint industry projects provide a basis for estimation of the critical buckling load of a straight, or in some cases imperfect, pipe on either a rigid or elastic seabed. However, systematic solutions for the combined effects of nonlinear soil properties and the as-laid geometry – specifically the out-of-straightness – on the buckle initiation behaviour have not been developed previously. This paper reports an investigation of the buckling problem of an imperfect (non-straight) on-bottom pipeline subjected to axial compressive loading. The seabed was modelled with lateral and axial nonlinear, springs to idealise the load-displacement behaviour of the soil and the pipe was modelled with pipe elements. Buckling was performed by a displacement controlled finite element method with the modified Riks algorithm that is available in the commercial software ABAQUS. This numerical tool was used to develop a parametric solution for the present problem in terms of the various pipe material and geometry parameters and the lateral and axial pipe-soil interaction parameters. In particular, the influence of the magnitude and stiffness of the lateral pipe-soil response was investigated, highlighting the sensitivity of the pipeline response to the geotechnical inputs. The results have been synthesised in a generic non-dimensionalised design chart to estimate the buckling load, valid for the range of inputs covered by the parametric study.

Improved buried pipe element method for temperature-field calculation of mass concrete with cooling pipes

PurposeThe buried pipe element method can be used to calculate the temperature of mass concrete through highly efficient computing. However, in this method, temperatures along cooling pipes and the convection coefficient of the cooling pipe boundary should be improved to achieve higher accuracy. Thus, there is a need to propose a method for improvement.Design/methodology/approachAccording to the principle of heat balance and the temperature gradient characteristics of concrete around cooling pipes, a method to calculate the water temperature along cooling pipes using the buried pipe element method is proposed in this study. By comparing the results of a discrete algorithm and the buried pipe element method, it was discovered that the convection coefficient of the cooling pipe boundary for the buried pipe element method is only related to the thermal conductivity of concrete; therefore, it can be calculated by inverse analysis.FindingsThe results show that the buried pipe element method can achieve the same accuracy as the discrete method and simulate the temperature field of mass concrete with cooling pipes efficiently and accurately.Originality/valueThis new method can improve the calculation accuracy of the embedded element method and make the calculation results more reasonable and reliable.

Image-based fracture pipe network modelling for prediction of coal permeability

In coal seam gas (CSG) reservoirs, the underlying fracture networks play a critical role in controlling flow pathways of methane and water phases. Thus, study of flow in fracture networks via different numerical modelling methods is of importance. Compared to direct flow simulation, the Fracture Pipe Network Model (FPNM) is an effective means of modelling fluid flow in a fracture network due to its computational efficiency. However, constructing FPNM for authentic samples is challenging due to the limited fracture data at the core scale. In addition, application of FPNM for coal is challenging due to its complex internal fracture network. With X-ray micro-computed tomography (micro-CT) imaging, internal fracture network of coal samples can be visualised non-destructively, providing deterministic input data for FPNM. However, analysing fractures individually and characterising network connectivity based on micro-CT images are difficult, due to complex interactions, irregular fracture geometry, resolution limitation and image noises. In this paper, we develop a framework for constructing image-based FPNM for real fractured coal cores for fast prediction of permeability. Compared with conventional FPNM, each pipe element of our improved FPNM has the identical properties (orientations, length, aperture and roughness) with its corresponding data from the real sample. By comparing permeability values obtained from FPNMs, micro-CT images and voxelised DFNs, we conclude that FPNM can effectively estimate the permeability of original fracture networks while requiring significantly lower computational cost that make it a suitable framework for expensive multi-phase multiphysics flow simulations.

The improved methodology for calculating elements for fastening suspended pipes at installing explosion-proof bulkheads

The authors reviewed and improved the methodology for calculating fastening elements of the suspended pipes in the explosion-proof bulkhead, when it is exposed to a shock wave, with taking into account influence of angles of the fastening element inclination relatively to the vertical and horizontal planes of the roadway. For determining forces in the fastening elements of the suspension with accounting influence of angles of vertical and horizontal working planes, and for choosing a suspended pipe fastening bearing the greatest load, three types of the suspended pipe fastening were considered for mounting explosion-proof bulkheads in the belt road 2, longwall №10, of the private joint-stock company “Pokrovskoye”. A scheme is proposed for calculating the suspended pipe elements to be fastened to the structural elements of the arch support. By applying an analytical method based on the laws and regulations of theoretical mechanics, a coefficient k formula is given, which takes into account angles of the elements fastening relatively to the horizontal and vertical planes with the view of obtaining more accurate calculation of the forces acting in the elements of the suspended pipes fastened to the elements of arch support and choosing proper diameters for them in the existing normative documents. In the article, three schemes of the suspended pipe fastening are considered. An actual load on the suspended pipe fastening elements are calculated with accounting coefficient k, and discontinuity of the fastening elements are calculated for the three types of the suspended pipe fastening and their chosen sections. The proposed types of fastening of suspended pipes in the explosion-proof bulkheads and their calculation will allow the head of an accident liquidation service to choose the type most suitable for practical implementation in specific circumstances and, therefore, to improve safety of miners. On the basis of the considered types of suspended pipes fastening to the structural elements of the arch support and calculation of the occurred reactionary efforts caused by the shock wave, the authors of the article recommend to fasten suspended pipes by six chains because this type is more reliable and requires essentially less labor content when making the fastening elements for the suspended pipe by using combine or conveyor chains available at the mine.

Effectiveness of Several Metaheuristic Methods to Analyze Hydraulic Parameters in a Drinking Water Distribution Network

The reliability and ease of applying metaheuristic methods in solving large and complex equation systems make it interesting to be applied as an alternative solution to solving problems in various fields. This article proves the effectiveness of an optimization model based on the metaheuristic method for the analysis of hydraulic parameters of drinking water distribution pipes. The metaheuristic methods explored are Differential Evolution (DE) algorithm, Particle Swam Optimization (PSO) algorithm and CODEQ algorithm. The effectiveness of the three methods is measured relative by comparing the results of the analysis of the three models with the results from Newton Raphson method and Monte Carlo simulation method. The analysis shows that the optimization model based on the DE, PSO and CODEQ algorithms is very effective for solving problems on a simple network that has 6 pipe elements and 5 service nodes. The results obtained have a level of accuracy as good as Newton Raphson method. In the case of complex networks that have 32 pipe elements and 21 service nodes, there is an indication of performance degradation which is indicated by a decrease in fitness value. In this case, Newton Raphson method still shows its consistency. The optimization model based on the metaheuristic method is still far more effective than the Monte Carlo simulation method, although it is not as effective as Newton Raphson method. The Monte Carlo simulation method is not recommended for hydraulic pipe network analysis, even for simple networks.

Study on the effect of corrosion defects on VIV behavior of marine pipe using a new defective pipe element

After long-term service in deep ocean, pipelines are usually suffered from corrosions, which may greatly influence the Vortex-Induced Vibration (VIV) behavior of pipes. Thus, we investigate the VIV of defective pipelines. The geometric nonlinearity due to large deformation of pipes and nonlinearity in vortex-induced force are simulated. This nonlinear vibration system is simulated with finite element method and solved by direct integration method with incremental algorithm. Two kinds of defects, corrosion pits and volumetric flaws, and their effects of depth and range on VIV responses are investigated. A new finite element is developed to simulate corrosion pits. Defects are found to aggravate VIV displacement response only if environmental flow rate is less than resonance flow rate. As the defect depth grows, the stress responses increase, however, the increase of the defect range reduces the stress response at corroded part. The volumetric flaws affect VIV response stronger than the corrosion pits.

Improving the Resilience of Postdisaster Water Distribution Systems Using Dynamic Optimization Framework

Improving the resilience of water distribution systems (WDSs) to handle natural disasters (e.g., earthquakes) is a critical step toward sustainable urban water management. This requires the water utility to be able to respond quickly to such disaster events, and in an organized manner, to prioritize the use of available resources to restore service rapidly while minimizing the negative impacts. Many methods have been developed to evaluate the WDS resilience, but few efforts are made so far to improve the resilience of a postdisaster WDS through identifying optimal sequencing of recovery actions. To address this gap, the authors propose a new dynamic optimization framework in this study in which the resilience of a postdisaster WDS is evaluated using six different metrics. A tailored genetic algorithm is developed to solve the complex optimization problem driven by these metrics. The proposed framework is demonstrated using a real-world WDS with 6,064 pipes. Results obtained show that the proposed framework successfully identifies near-optimal sequencing of recovery actions for this complex WDS. The gained insights, conditional on the specific attributes of the case study, include the following: (1) the near-optimal sequencing of a recovery strategy heavily depends on the damage properties of the WDS; (2) replacements of damaged elements tend to be scheduled at the intermediate-late stages of the recovery process due to their long operation time; and (3) interventions to damaged pipe elements near critical facilities (e.g., hospitals) should not be necessarily the first priority to recover due to complex hydraulic interactions within the WDS.

Профилирование проточной части нагнетательного канала аксиально-поршневого насоса

The article considers the flow of the working fluid in the discharge channel of the axial piston pump with end distribution. Geometric region shapes of the channels, currently used in axial piston pumps, negatively affecting the dynamic parameters of the flow flowing through it, are determined by numerical simulation. The configuration of the channel cavity allowing a more uniform distribution of dynamic parameters over the volume of the fluid flow is proposed. The optimal ratio between the reference dimensions adopted for constructing a three-dimensional model of the channel was determined based on the study of the dependence of the power factor value, the amount of movement in the output section vs the shape of the channel. Energy loss due to flowing the working fluid through the channel is reduced. The resulting force effect on the discharge pipe and other elements connected to the pump is reduced and the vibroacoustic characteristics of the pump unit are improved.

Experimental analysis of wood pellet degradation during pneumatic conveying processes

The size reduction of wood pellets during pneumatic transport in a laboratory test rig is investigated. For the quantification of pellet breakage and attrition, the length distribution of each bulk sample is measured in combination with the gravimetrical determination of the amount of fines before and after every conveying step. In laboratory tests a variation of pipe elements (bend radii, couplings, pipe reducer or cyclone separator), air volume and product mass flows and pellet quality is investigated. Additionally, particle velocities are determined with a stereoscopic high-speed camera set.Results demonstrate the strong dependence of wood pellet degradation on operating conditions and selection of pipe components. Increasing air volume flow and, thus, higher particle velocities induce particle size reduction, whereas increasing pellet mass flow has the opposite effect, although the influence is weak. Increasing pipe length or decreasing bend radius leads to progressive formation of fines.

Propagating uncertainties in large-scale hemodynamics models via network uncertainty quantification and reduced-order modeling

Numerical simulations of the cardiovascular system are affected by uncertainties arising from a substantial lack of data related to the boundary conditions and the physical parameters of the mathematical models. Quantifying the impact of this uncertainty on the numerical results along the circulatory network is challenged by the complexity of both the morphology of the domain and the local dynamics. In this paper, we propose to integrate (i) the Transverse Enriched Pipe Element Methods (TEPEM) as a reduced-order model for effectively computing the 3D local hemodynamics; and (ii) a combination of uncertainty quantification via Polynomial Chaos Expansion and classical relaxation methods – called network uncertainty quantification (NetUQ) – for effectively propagating random variables that encode uncertainties throughout the networks. The results demonstrate the computational effectiveness of computing the propagation of uncertainties in networks with nontrivial topology, including portions of the cerebral and the coronary systems.