Pipe Expansion Research Articles

Numerical study of multi-component flow and mixing in a scaled fission product venting system

Numerical simulation of isothermal multi-component gas flow was conducted to study fluid flow and mixing in a scaled low-pressure, low-temperature test facility for the fission product venting system (FPVS) of a gas cooled fast reactor (GFR). The geometry of FPVS test facility was an open loop including gradual expansion coupling and two 90°pipe elbows.First, the validation of large eddy simulation (LES) wall-adapting local eddy-viscosity (WALE) turbulent model was performed for transitional flow in a circular pipe with gradual expansion. The reactingFOAM solver in OpenFOAM v8 was employed. By introducing appropriate turbulence disturbance at the flow inlet, such as turbulence intensity, the numerical results showed good agreement in (1) the velocity profile downstream of the pipe expansion measured by particle image velocimetry (PIV) in this study, and (2) the reattachment length reported in the literature.Using this validated model, the numerical simulation of flow and component mixing was performed for the FPVS with an inlet flowrate corresponding to a Reynolds number of 2,400 to investigate the flow behavior and component mixing. Standard deviation of the mass fraction of component, referred to as absolute mixing index (AMI), was calculated to quantify the mixing of components, showing that the component mixing length determined by AMI is related to the reattachment length downstream of the expansion. Finally, this study was able to identify the best location in the FPVS test facility to measure the velocity and concentration profies where multicomponent flow is well mixed.

Численное исследование влияния неизотермичности на характеристики течения степенной жидкости в трубе с резким расширением

In this paper, a steady laminar non-isothermal flow of a power-law fluid in an axisymmetric sudden pipe expansion is numerically simulated. The rheological behavior of the fluid is described by the modified Ostwald-de Waele law; the apparent viscosity is an exponential function of temperature. The equations are written in terms of dimensionless stream function - vortex - temperature. No-slip conditions and zero temperature are used on the solid wall. At the inlet boundary, the velocity and temperature profiles correspond to a one-dimensional steady non-isothermal flow of the considered fluid. “Soft” boundary conditions are assigned at the outlet boundary. The formulated problem is solved using the finite-difference method. The structure of the flow through a sudden pipe expansion is shown to include one- and two-dimensional flow zones with a recirculation region occurring in the inner corner vicinity. The variation in the two-dimensional flow zone length is analyzed with respect to a power-law index and dimensionless criteria of the problem. Distributions of the velocity, temperature, and apparent viscosity are presented at various Peclet and Reynolds numbers for dilatant and pseudoplastic fluids.

Research on collapse failure characteristics and theoretical prediction formulas of Solid expandable tubular

Solid expandable tubular (SET) is plastically formed in the well, it needs to undergo the double test of internal and external pressure. The collapse resistance of the SET after expansion is an important guarantee for the wellbore structural integrity reconstruction. In addition, due to the diversity of the material of the SET and the complexity of plastic forming, there is no unified formula for calculating the collapse strength of the SET. Aiming at the above problems, this paper builds a three-dimensional dynamic collapse strength calculation Finite element model (FEM) based on the collapse experiment of SET, and analyzes the influence of expansion rate, wall thickness and eccentricity on the collapse strength of expansion pipes, and fits the theoretical calculation formula of collapse strength. The research results show that: the expansion rate causes the collapse performance of the pipe after expansion to be reduced by 15% to 30%; the wall thickness has almost a linear effect on the collapse performance; the greater the eccentricity, the lower the collapse strength, the more likely it is to “ Concave ”. Through data fitting, a theoretical prediction formula for the collapse strength of SET with a material of 20G and a diameter-to-thickness ratio of less than 30 is obtained. The formula is simple and easy to calculate using parameters. The research results in this paper provide theoretical guidance and methods for the study of the collapse strength of SET.

The role of expansion angle and speed on shish-kebab formation in expansion pipe extruder head explored by high temperature rapid stretch

Morphology and microstructures play a significant role on properties of polymer products. Self-reinforced shish-kebab formed inside the products by elongational flow induced orientation can improve the tensile strength and pressure rating properties, and the density of polymers consisting of shish-kebabs is fairly below those filled with glass fibers, basalt and talc. The threshold parameters to form shish-kebab structure in a novel annular expansion pipe extruder head were determined by high temperature rapid stretch (HTRS) in this study. Different morphologies of HDPE specimens made under the conditions in expansion head by HTRS were studied by SEM, 2D-WAXD and 2D-SAXS, specimen 7 with 15° and 6 mm/s base speed has the optimal shish-kebab structure and specimen 10 with 30° and 5 mm/s has the best orientation parameter and the best shish structure. The DSC results agree well with the morphology results shown in the SEM images. The specimen 7 displays the highest tensile strength, increases about 187% compared with the reference specimen. These outstanding properties were attribute to the perfect and compact shish-kebab structures inside it. The results of HTRS can prove a direction guide for extrusion processing.

Effect of annular expansion pipe extruder head on mechanical properties of pipes

AbstractWith polymer pipes being used more commonly, performance requirements are increasing. Studies on the enhancement of mechanical properties of polymer pipes are particularly important. In this study, a self‐designed annular expansion pipe extruder head was used to enhance the mechanical properties of HDPE pipes. Different morphologies of the HDPE pipes were produced under different processing conditions. When the extrusion angle was 30° (P30), the best mechanical properties were obtained. The hoop tensile strength and axial tensile strength were 14.5% and 41.0% higher, respectively, compared with the specimen without expansion (P0). This improvement of mechanical properties can be attributed to several reasons. First, the processing parameters of P30 reached the threshold shear rate and strain for shish‐kebab formation, as shown by scanning electron microscopy. Second, P30 has the highest orientation parameter and crystallinity of 0.679 and 67.27%, respectively, from 2D wide‐angle diffraction (WAXD). Polarized FTIR shows the same trend as 2D‐WAXD. Third, the outer bamboo‐like self‐reinforced structure is formed inside the pipe at 30° expansion angle while the core layer has a well‐formed crystal structure; the special structure improves the overall performance of HDPE pipe. This method can be utilized in large‐scale industrial production.

Experimental and mathematical methods for calculation of residual stresses in production of welded pipes

The results of physical and mathematical modeling of the stress-strain state of metal and residual stresses during plastic deformation of a sheet blank and welding of large-diameter pipes are generalized. One of the analytical methods for calculation of residual stresses during elastoplastic deformation of a rectangular bar and a wide strip is described. From the standpoint of continuum mechanics, it is shown that under the action of a bending moment, tensile stresses appear in the outer layers, and compressive stresses appear in the inner layers, which change sign during unloading and residual stresses remain in the metal, compressive stresses in the outer layers, and tensile stresses on the inner surface. As a result of the studies carried out, the authors for the first time obtained a picture of residual stresses distribution and found that at each technological operation of the formed pipe billet after its completion, tangential and axial residual tensile stresses σостmax/σв ≤ 0,31, act along the entire outer perimeter and length, which after expansion-calibration of pipes decrease to the magnitude σт σост/= 0,23σв and σост∞/= 0,18σв. Ii was established that the value and distribution of residual stresses are significantly influenced by the blank shape, the order of welds imposition, welding modes and mechanical properties of the metal. This conclusion was also confirmed by experimental studies of residual stresses, which were obtained by X-ray diffractometry and sequential etching of surface layers using the MerCulon «Tensor-3» system. The results of experimental studies have shown that during plastic deformation of the sheet blank and after welding, residual tensile stresses are observed on the outer surface in the pipe metal and in the weld, which can cause pipeline failure. The paper describes the results of numerical modeling of non-uniformity of the stress-strain state and residual stresses in the metal of pipe processing at all stages of production according to the JCO scheme: bending of the sheet edges → forming on a step-forming press → re-forming of the «spline pipe» - a pipe profile with divorced edges → calibration - pipe expansion. Based on the results of modeling by the finite element method, it is shown that the required geometric shape of the pipe and the dimensional accuracy of the LDP diameter are achieved when expanding the workpiece with an ovality of no more than 5 mm, while ensuring high-quality assembly and welding of edges of pipes to be joined in the line of the pipeline system.

Pressure Measurement during the Pipe Expansion Using the Magneto Hydro Impulse Method

Pressure Measurement during the Pipe Expansion Using the Magneto Hydro Impulse Method

Improvement of the heat transfer enhancement model considering the droplet-wall heat transfer downstream of the flow blockage in the reflood phase

When a flow blockage is formed by fuel swelling in the reflood phase of a large-break loss-of-coolant-accident (LOCA) in a pressurized water reactor (PWR), flow separation and reattachment occur due to the flow area change downstream of the blockage. These phenomena increase turbulence and vorticity in the downstream, resulting in the enhancement of heat transfer by steam and liquid droplets. The existing heat transfer enhancement model has considered the enhancement factor for the single-phase heat transfer only. For the assessment of the existing model, it was implemented in the CUPID code in which a two-fluid three-field model is applied. The existing model was evaluated using the FEBA flow blockage test without flow bypass. As a result, the existing model greatly over-predicted the rod temperature downstream of the blockage. To improve this, a new enhancement model was proposed that considers the wall heat transfer by the droplet deposition. The heat transfer enhancement factor was derived based on the data from the abrupt pipe expansion experiments that measured heat and mass transfer coefficients after flow separation point. For accurate calculation of the amount of droplets approaching the fuel rod, an improved droplet deposition model was developed using the droplet deposition experimental data for dispersed droplet and annular-mist flow. The new model implemented in the CUPID code was evaluated using the FEBA flow blockage tests with different pressure, flooding rate, and blockage ratio. It was shown that the new model gave good predictions for the temperature of the early cooled rod bundle downstream of the blockage.

Analysis of Symmetrical and Nonsymmetrical Vertical Expansion Loop to Increase Flexibility And Reduce Pipe Stress Based On ASME B31.3

Thepiping system is a medium used to convey, distribute, mix, separate, discharge, meter, control or snub fluid flows, and transmit a fluid pressure. The piping system design will have stresses due to thermal and pressure effect. The thermal effect induce pipe expansion. The pipe expansion affect to pipe flexibility, so it is necessary to design an expansion loop. Expansion loop is a method used to increase flexibility in piping systems. This article aims to analyze symmetrical and non-symmetrical in vertical expansion loops whether it can increase flexibility and reduce pipe stress. This article conducts an expansion loop design with 3 trials, namely trial 1 (Vertical Expansion Loop), trial 2 (Nonsymmetrical Vertical Expansion Loop 1), and trial 3 (Nonsymmetrical Vertical Expansion Loop 2). The three trials were compared for flexibility and stress values based on ASME B31.3 requirements. The study results show that all trial 1, trial 2, and trial 3 have good flexibility with a value of 0.00016 because not exceed the requirements of ASME B31.3. The highest design code stress value in trial 1 is 5955 psi (Node A07F), trial 2 is 5906 psi (Node A05F), and trial 3 is 5906 psi (Node A06N). All trials have a code stress not exceeding the allowable stress (20000 psi). So that the symmetrical or nonsymmetrical design of the vertical expansion loop can both increase flexibility and reduce pipe stress.

Pipe Stress Analysis of Pump System in Process Plant

Every process and LNG plants operate many pumps and compressors in the processing unit. Performing the pump stress Analysis is immensely critical. The Pump’s high vibration on the process plant will seriously affect the pipe and equipment’s smooth operation. The resonance effect between pipe and equipment will create a severe additional desecration. Before installation or formal process, we need to perform static analysis, and dynamic analysis (modal, forced response analysis) is mandatory for the pump system. The pump vendor must perform a Pulsation analysis on the piping system for reciprocating machinery subject to pulsation flow. In this study, flexibility analysis of pump piping system as per process piping code B31.3 using CAESAR-II programming followed by placing of diverse pipe supports. The support type and position of the supports as per the output get from static and dynamic examination. By the software analysis of CAESAR II, the efficiency of pipe flexibility and expansion of the piping system’s natural frequency is authenticating by include more oriented and load-bearing support to the elbow and Valve, which prevents the resulting of resonance successfully. The stress analysis, modal analysis, pulsation analysis, and vibration analysis method proposed in this paper will increase the lifespan and operation reliability of pipe and equipment.

Validation of Clicking-type Noise and Vibration in Automotive HVAC System

In this study, the characteristics of clicking-type noise and vibration occurring in the automotive heating, ventilation and air conditional (HVAC) systems are investigated. A lab-scale model of HVAC system is developed, and validation is carried out with a vehicle system. A fixed blower speed of 1 (at an airflow of 2.53 m/s) with alternated air conditional (AC) was implied in this study. Three different sensors namely as tachometer, accelerometer, and microphone were used to measure and prove the existing noise in the HVAC system. The study inferred that the compressor contributed significantly to the total vibration and noise in the HVAC system. Other components such as AC pipe, evaporator, and thermal expansion valve (TXV) also contributed to a slight extent. The clicking noise was observed in the operating frequency range of 200 ~ 300 Hz. This noise and vibration issues are partly influenced by the running conditions of the AC and the effect was significant when the AC was turned on. The validation of the findings in the model shows a good agreement with the results obtained in the vehicle system, whereby the clicking noise and vibration can be observed at a similar frequency range.

Study on Forming Theory of Inner Strong & Outer Weak Strong Bi-metal Pipe

As a new type of pipe, bimetallic composite pipe is widely used in various industries in the chemical industry, because its internal and external tubes use different metals, so it can cope with a variety of different working conditions. At present, the application field of composite pipe is mostly inner strong and outer weak strong composite pipe, and this pipe has not been studied accordingly. In this paper, the theory of expansion of inner strong and outer weak strong composite pipe is derived, and a complete set of expansion methods and related parameter calculation formulas are obtained. Abaqus, a finite meta-analysis software, is used to simulate the expansion process and compare it with the theoretical results. The comparative results show that the theoretical formula obtained by derivation has a high degree of credibility, and the results obtained by using this set of theories are close to the results of computer simulation and can be used in industrial production.

Shortcut Method for “L” and “Z” Pipe Bend Sizing

Abstract In the engineering practice, it may often prove necessary to provide quick and relatively accurate estimates of piping routing and material requirements in very early stages of a project. In these cases, there is typically no time to perform detailed pipe stress analysis in order to obtain accurate routing, which allows for sufficient piping system flexibility, and the designer is constrained to the use of rule of thumb approach and good engineering judgment. This approach, although often used, may prove challenging in many situations, one of which is establishing sufficient pipe loop dimensions. Method proposed by the authors in Jacimovic and Ivosevic (2020, “Shortcut Method for Pipe Expansion Loop Sizing,” ASME J. Pressure Vessel Technol. 142(4), p. 041505) provides a procedure for quick estimation of U loops, while the present procedure aims to provide additional procedures for estimation of L and Z bends, thus completing the circle of shortcut methods for quick estimation of expansion requirements of piping systems.

Erosion-Corrosion of AISI 302 Stainless Steel Sudden Expansion Pipes in High Salt Wastewater: Effect of Fluid Flow on Different Positions of a Sudden Expansion Pipe

Erosion-corrosion (E-C) is common in chemical industries. Sudden expansion pipes (SEP) are one of the flow components which may experience severe erosion rates. Computational fluid dynamic modeling (CFD) and flow-through experiments were used to study E-C for a SEP of AISI 302 stainless steel. A typical geometry for SEP was investigated: 20 mm diameter inlet pipe, 40 mm diameter outlet pipe, with an inlet flow rate of 0.1 m/s, and 10 wt% concentration of SiO2. CFD simulation results showed that turbulence energy and wall shear were highest at 5 mm and fluid axial velocity was lowest at 5 mm from the inlet/outlet SEP connection point. E-C test results showed that the most severe E-C occurred between 5 mm and 7 mm downstream of the SEP. At deeper lengths into SEP, the corrosion rate decreased and remained constant. The results indicated that increasing wall shear and turbulence energy increased the mechanical effects of particles on SEP and hence increased the E-C rates of the reattachment point. This work provides a means of understanding E-C behavior and predicting erosion damage of SEP.

Investigation on Gas-Soot Flow Distribution Characteristic of Soot Capture Process in the Wall-Flow Diesel Particulate Filter

In order to investigate the distribution characteristics of gas-particle two-phase flow in the diesel particulate filter in the capture process, a mathematical model of gas-particle two-phase flow for inside-and-outside filter had been established in the capture process according to the mass conservation equation, momentum conservation equation, and k-ε turbulence equation. The model verification was carried out with the experimental and simulated of flow distribution characteristics of gas-particle two-phase. The obtained results showed that the static pressure gradient along the radial distribution was greater at the inlet of the filter in capture process in the diesel particulate filter, which could easily lead to causing eventual fatigue damage due to stress concentration in the front-end of filter; moreover, the weaker the vortex strength of gas-particle formed in expansion pipe was, the better uniformity of flow velocity and soot concentration distribution were. Therefore, the established mathematical model can be used for predicting gas-particle flow velocity distribution in the diesel particulate filter.

Расчет гидравлического сопротивления при плавном расширении и сужении горизонтальной трубы

The main results of the calculation of the head loss with a smooth expansion and narrowing of the horizontal pipe, which has the following geometric dimensions; - the inner diameter of the pipe with a narrowing of 25 mm and an expansion of 50 mm. The pressure loss of the smooth expansion of the pipe at an oil velocity of 0.2–1.0 m/s has a smooth rate of increase from 0.002 to 0.032 m. With a smooth narrowing of the pipe, the head loss is from 0.0021 to 0.024 m. That, during the movement of oil in a horizontal pipe, the head loss with a sudden expansion is 1.33 times greater than that of a sudden narrowing.

Flow Structures on a Planar Food and Drug Administration (FDA) Nozzle at Low and Intermediate Reynolds Number

In this paper, we present a general description of the flow structures inside a two-dimensional Food and Drug Administration (FDA) nozzle. To this aim, we have performed numerical simulations using the numerical code Nek5000. The topology patters of the solution obtained, identify four different flow regimes when the flow is steady, where the symmetry of the flow breaks down. An additional case has been studied at higher Reynolds number, when the flow is unsteady, finding a vortex street distributed along the expansion pipe of the geometry. Linear stability analysis identifies the evolution of two steady and two unsteady modes. The results obtained have been connected with the changes in the topology of the flow. Finally, higher-order dynamic mode decomposition has been applied to identify the main flow structures in the unsteady flow inside the FDA nozzle. The highest-amplitude dynamic mode decomposition (DMD) modes identified by the method model the vortex street in the expansion of the geometry.

Method of Calculating the Compensation for Rectifying the Horizontal Displacement of Existing Tunnels by Grouting

Sleeve valve pipe grouting, an effective method for reinforcing soil layers, is often employed to correct the deformation of subway tunnels. In order to study the effect of grouting on rectifying the displacement of existing tunnels, this paper proposes a mechanical model of the volume expansion of sleeve valve pipe grouting taking into consideration the volume expansion of the grouted soil mass. A formula for the additional stress on the soil layer caused by grouting was derived based on the principle of the mirror method. In addition, a formula for the horizontal displacement of a tunnel caused by grouting was developed through a calculation model of shearing dislocation and rigid body rotation. The results of the calculation method proposed herein were in good agreement with actual engineering data. In summary, enlarging the grouting volume within a reasonable range can effectively enhance the grouting corrective effect. Further, with an increase in the grouting distance, the influence of grouting gradually lessens. At a constant grouting length, setting the bottom of the grouting section at the same depth as the lower end of the tunnel can maximize the grouting corrective effect.

Maximum allowable fluid velocity and concern on piping stability of ITER Tokamak cooling water system

The ITER facility is an international research project that is under construction in Cadarache, France. US ITER is responsible for the design, engineering, and procurement of the Tokamak Cooling Water System (TCWS). TCWS piping size varies from DN40 to DN500. A design guideline specifies that piping smaller than DN150 must have a fluid velocity below 6 m/s, while a fluid velocity of up to 9 m/s is permitted for piping larger than DN150. Fluid velocity affects pipe size, pressure drop, pump size, piping support, etc. Factors considered when determining maximum allowable fluid velocity include erosion and corrosion, pump capacity, cavitation, hydrodynamic instability, and actual nuclear plant experience. The previous study performed to support the ITER piping design indicated that the hydrodynamic instability was a reason to limit maximum allowable fluid velocity below 6 m/s regardless of the piping size. However, the later study found that, when properly supported, pipe buckling and fluttering from hydrodynamic force would not cause instability. Instead, cavitation erosion—a pipeline phenomenon that forms vapor cavities in pipe—may limit allowable fluid velocity. Cavitation is a pipeline phenomenon that forms vapor cavities, which then go unstable and collapse violently in low-pressure, turbulent, flow-separation regions inside valves, elbows, pipe expansions, and other fluid handling components. Considering the cavitation issue, pressure drop, and a typical practice in a nuclear plant system, fluid velocity is to limit below 6 m/s for piping smaller than DN150 and 9 m/s for piping larger than DN150. This paper describes a hydraulic stability analysis, the fluid velocity generally accepted in nuclear plants and the cavitation-erosion limit in fluid velocity.

Crashworthiness Characteristic of Dynamically Expanded Circular Tubes Made of Light Alloys: Experimental and Theoretical Investigation.

The paper presents the process of dynamic expansion of thin-walled pipes made of T6 temper 7075 aluminum alloy. The obtained results were related to the mass of tested elements, which allowed for calculating the specific energy absorption. The registered crushing force was in the range of 600–800 kN/kg. The obtained values were much greater than the crushing force of traditional crash boxes made of steel (80–120 kN/kg) or AZ31 magnesium alloy sheets (150 kN/kg). The analytical model for predicting crushing force depending on the thickness of the pipe wall was developed and proven to be correct by conducting real experiments and FEM simulation. The mathematical model for energy absorption named further as ETMEA (expanding tubes model for energy absorption) was developed based on calculated energy-deflection curves. It was proven that the energy absorption could be easily scaled. In cases where high energy absorption is needed, it can be easily achieved by increasing the thickness, while for lower energy absorption application, the thickness may be reduced and the goal may be achieved by selecting the appropriate length of the profile.