Shape Of Pipe Research Articles

Cost effective simulation-based multiobjective optimization in the performance of an internal combustion engine

Solving real-life engineering problems can be difficult because they often have multiple conflicting objectives, the objective functions involved are highly nonlinear and they contain multiple local minima. Furthermore, function values are often produced via a time-consuming simulation process. These facts suggest the need for an automated optimization tool that is efficient (in terms of number of objective function evaluations) and capable of solving global and multiobjective optimization problems. In this article, the requirements on a general simulation-based optimization system are discussed and such a system is applied to optimize the performance of a two-stroke combustion engine. In the example of a simulation-based optimization problem, the dimensions and shape of the exhaust pipe of a two-stroke engine are altered, and values of three conflicting objective functions are optimized. These values are derived from power output characteristics of the engine. The optimization approach involves interactive multiobjective optimization and provides a convenient tool to balance between conflicting objectives and to find good solutions.

Rheology of colloidal gas aphrons (microfoams)

This paper reports on the effect of surfactant concentration and pipe shape and size on the rheological properties of colloidal gas aphrons (CGAs) or microfoams. CGA consists of closely packed spherical gas bubbles with diameter ranging from 10 to 100μm surrounded by a surfactant shell. It is produced by stirring an aqueous surfactant solution at high speed in a baffled beaker. Pipe flow experiments were performed in cylindrical pipes with diameter ranging from 1.0 to 3.0mm under adiabatic laminar flow conditions. The porosity, bubble size distribution, surface tension, and pH were systematically measured. First, it is established that there was no slip velocity at the wall and CGA did not change morphology and porosity between the inlet and outlet of the pipes less than 2mm in diameter. Compressibility effects were accounted for through the volume equalization approach. Then, pipe shape and diameter have no effect on the CGA rheology. Finally, CGA can be considered as a shear-thinning fluid. The dimensionless volume equalized shear stress τ* is proportional to (Ca*)m where Ca* is the Capillary number and m=0.65±0.06. The results are in good agreement with theoretical models suggesting τ*=C(x)(Ca*)2/3 where C(x) is determined experimentally. It is established that C(x) increases with surfactant mass fraction x. The Fanning friction factor f for CGA under laminar flow conditions follows the standard relationship f=16/ReD where Reynolds number is determined using the CGA effective viscosity given by μe=μlC(x)Ca−1/3.

Pipe Shape Solution of Faddeev Model

Utilizing the results that the Faddeev model is equivalent to the mesonic sector of the SU(2) Skyrme model, where the baryon number current vanishes everywhere, some exact solutions including the vortex solutions of the Faddeev model are discussed. The solutions are classified by the first Chern number. When the Chern number equals 2, the new multisoliton solutions are obtained and the pipe shape distribution of the energy density of the solutions are found.

The rock mechanics of kimberlite volcanic pipe excavation

The rock mechanics theory for deformation of open pit and underground mining excavations can be used to better understand aspects of the growth and geometry of kimberlite volcanic pipes. Large scale rock mass behaviour around an excavation, such as a volcanic pipe, is dependent on the rock mass strength, the in-situ rock stress conditions and the excavation geometry. Rock mass strength is empirically derived from the intact rock strength and quantification of the shear strength, frequency and orientation of rock discontinuities. Tensile slope or sidewall failure typically occurs in shallow level (~ 0–1000 m) conditions in which pre-existing structures shear due to gravity-driven forces. The orientation of the pre-existing structures provides an important control on the size, shape and position of the rock mass failure. Slope failures are shown to influence the development of many kimberlite volcanic craters and the distribution of layered volcaniclastic facies in the crater. Explosions or removal of key-blocks in a pipe sidewall can cause undercutting and collapse of the sidewall, with the rock unravelling along pre-existing structures towards surface. Many lithic-rich breccias commonly found on the margins of kimberlite pipes are interpreted to form in this way. At intermediate (> 1000 m) to deep (> 2500 m) depths, the increasing compressive stress can cause fractures to develop around an excavation. Stress-induced fractures should cause scaling of a volcanic pipe's sidewalls and expansion perpendicular to the maximum component of compressive stress. A larger horizontal tectonic stress ratio and a lower internal pipe pressure will promote pipe sidewall fracturing. Volcanic pipe expansion will also be increased in rate by (i) mechanical sidewall erosion by flowing magma and/or pyroclasts, (ii) by failure on large intersecting fault or dyke structures, and (iii) by reduction in the country rock mass strength by volcanic explosions. The final pipe shape and distribution of some internal facies is therefore a consequence of the dominant rock mechanical failure processes in the pipe sidewalls. The type of failure is dependant on the rock mass strength, geological structures, stress and depth below surface.

Thermal and flow behaviors in heat transportation container using phase change material

A waste heat transportation system using a phase change material (PCM) – the so-called trans-heat (TH) system that uses a direct heat exchanger with an extremely simple structure to store and release the latent heat of PCMs – is quite attractive. The purpose of this paper is to study the thermal and flow behaviors in a TH container in which the solidification and melting of PCMs are directly observed by using a two-dimensional, roundly sliced model. In the heat storage experiments, we observed many HTO channels within the solid PCM in the early stage, which caused a large heat storage rate. In the final stage, the heat storage rate was extremely small; leading to the formation of a dead zone for the solid PCM in the lower part of both ends of the container owing to the non-uniform distribution of the HTO. In the heat release experiments, interestingly, the observed features of the solid PCMs were classified into three types; formation and growth of solidified PCM masses in the inlet pipes, sinking of solidified PCM particles and foaming oil coated by solidified PCM film. In particular, the sinking of the solidified PCM particles was effective for mixing the liquid PCM and cooling the container uniformly. The results revealed that the shape of the inlet pipes should be designed by considering their position, the number of pipes and the nozzle angle using a sophisticated heat and fluid flow model to maximize the heat exchange rate.

Comparison of two 2D laser scanners for sensing object distances, shapes, and surface patterns

Laser scanners are increasingly used in automation and robotic applications as a sensing device for navigation and safety. They have agricultural applications in measuring plant growth rate, tree volume, tree count, 3D imaging, and pattern recognition. Laser scanners are commercially available, but there is very little published information on characteristics and performance of these laser scanners. This study compared two laser scanners, the Sick LMS200 and the Hokuyo URG-04LX, for measurement drift over time, the effect of material and color on measurement accuracy, and the ability to map different surface patterns. Measurement drift over time was studied by determining the distance between the laser scanner sensor and a stationary object at different fixed distances and angles. Distance measurements over time fluctuated with a peak-to-peak value of 10–20 mm. The settling time, which is the time required for the averaged distance data to reach a stable level, increased when measurement distance increased but for a given distance, the settling time remained constant for different angles. At the measurement angle of 90°, the settling times for the LMS200 and the URG-04LX for 50% of the maximum scanner measurement distances were 53 min and 70 min, respectively. Therefore, to obtain accurate distance measurements, the laser scanners should be warmed up for the duration of the settling time before recording measurement data. The measured distance for soft material objects, such as a styrofoam plate and a sheet of dry sponge, was longer than the actual distance. For shiny objects, such as orange tree leaves, transparency film, and a stainless steel plate, the measurement distance was shorter than actual distance. At the measurement angle of 90°, the difference between the longest and shortest measured distance (90% of the maximum scanner measurement distance) was 21.3 mm for the LMS200 and 29.7 mm for the URG-04LX. At the measurement angle of 45°, this difference increased to 73.2 mm for the LMS200; the URG-04LX was not able to detect any objects at 45°. The surface shapes of a cylindrical pipe, a folded cardboard plate with a square-shaped valley, and a folded cardboard plate with a V-shaped valley were well-depicted by the laser scanner. For the object with a V-shaped valley with a true depth of 6.1 cm, the averaged depths measured by the LMS200 and URG-04LX were 6.8 cm and 3.6 cm, respectively. The larger discrepancy in the URG-04LX depth measurement may be caused by the relatively lower angular resolution of the URG scanner, compared to that of the LMS scanner.

Fabrication and Application of an Oxide Thermoelectric System

A plate‐shaped thermoelectric module was prepared using 140 pairs of p‐type Ca3Co4O9 (Co‐349) and n‐type LaNiO3 (Ni‐113) bulks. The hot‐pressed thermoelectric oxide bulks were connected with an Ag paste, incorporating oxide powder, and Ag sheets. The module's open‐circuit voltage increases with increasing hot‐side temperature (TH) and reaches 4.5 V at a TH of 1072 K in air. No deterioration in output power was seen when power generation was carried out 10 times at a TH of 723 K with intermediate cooling to room temperature. The module was successfully used to charge a lithium‐ion battery in a mobile phone. Thermoelectric modules composed of p‐type Co‐349 and n‐type CaMnO3 (Mn‐113) bulks, which have a pipe shape, were constructed using Ag electrodes and stainless‐steel tubes. The devices were connected with the stainless‐steel tube coated with ZrO2 by thermal spray using a dielectric paste composed of silica glass and iron oxide. Power generation was carried out in flame by combustion of natural gas. Water flowed inside the stainless‐steel tube for cooling. One module consisting of 54 pairs of legs can generate 1.5 V, 0.28 W, and steam simultaneously by installing in an instantaneous water heater. Power generation was carried out four times with intermediate cooling. Deterioration in the open‐circuit voltage of the module was not observed after the fourth combustion.

Measuring and modelling sewer pipes from video

This article presents a system for the automatic measurement and modelling of sewer pipes. The system recovers the interior shape of a sewer pipe from a video sequence which is acquired by a fish-eye lens camera moving inside the pipe. The approach is based on tracking interest points across successive video frames and posing the general structure-from-motion problem. It is shown that the tracked points can be reliably reconstructed despite the forward motion of the camera. This is achieved by utilizing a fish-eye lens with a wide field of view. The standard techniques for robust estimation of the two- and three-view geometry are modified so that they can be used for calibrated fish-eye lens cameras with a field of view less than 180°. The tubular arrangement of the reconstructed points allows pipe shape estimation by surface fitting. Hence, a method for modelling such surfaces with a locally cylindrical model is proposed. The system is demonstrated with a real sewer video and an error analysis for the recovered structure is presented.

Novel approach to PE pipe insertion using four-lobe vacuum collapse

The authors have researched, and partially developed, a novel concept for temporarily reducing the external diameter of a polyethylene (PE) pipe and then allowing recovery to full diameter as a close fit within a host main. The novelty lies in the four-lobed collapsed pipe geometry, which provides an efficient reduction of overall outside diameter without excessive strain and in the achievement and maintenance of this collapsed shape by vacuum. The further attraction of this approach is that controlled release of the vacuum provides a substantial primary recovery of the original pipe size and shape. The inventive discovery that makes possible the control of the four-lobe collapse state involves strict and progressive control of the collapse process, which can, in principle, be conducted downstream of the extrusion process, making continuous manufacturing, and indeed, coiling, feasible. Alternatively the collapse process could be made an on site operation immediately before insertion. The present work was largely conducted using a highly elastic grade of PE (Dow-DuPont 'engage' polymer) that maximised the high shape recovery potential of the process. Using this tough, rubbery form of PE pipe it was demonstrated that almost full pipe geometry could be recovered after release of vacuum. The technique is also applicable to conventional pipe grade PE materials, but with their stiffer viscoelastic properties recovery would require some internal pressure and perhaps elevated temperature for full recovery of circularity. The 'engage' PE polymers were found to be potentially useful materials for pipe lining since they are intrinsically tough and appear to be entirely weld compatible with conventional PE pipes. Engage liners could be electrofused to PE pipe. Iron pipe lined with a pressurised engage pipe was artificially fractured and subjected to severe angular offset without damage to the lining.

Viscous flow through pipes of various cross-sections

An interesting variety of pipe cross-sectional shapes can be generated, for which the Navier–Stokes equations can be solved exactly. The simplest cases include the known solutions for elliptical and equilateral triangle cross-sections. Students can find pipe cross-sections from solutions of Laplace's equation in two dimensions, and then plot the velocity distribution in the pipe. The total flow for a given pressure gradient and pipe area can be readily compared for different pipe shapes.

Long‐term changes in stream bank soil pipes and the effects of afforestation

Natural soil pipes are now recognized as potentially significant elements in hillslope drainage systems, sometimes developing into open channel tributaries or contributing often substantial volumes of quick flow to streams. However, there has been no detailed, long‐term monitoring study of the evolution of pipe networks to indicate how permanent they are or how readily they may develop into open channels. This paper reports a resurvey of a section of stream bank in the English Peak District and compares it with the original survey 35 years previous. Comparison of the distribution, size, and shape of pipes on both banks of a 250 m stretch of the stream reveals significant changes. There were no cases of roof collapse forming new open channels. However, there has been a significant change in land use within the basin, with afforestation of the east bank. The resurvey shows a marked reduction in the number and size of pipes on the forested bank, but no significant change on the opposite bank that has remained moorland. The number of pipe outlets on the afforested bank halved over the period, and their mean diameter has reduced by 30%. In combination with the reduced number the smaller size resulted in a 71% reduction in the total area of stream bank occupied by pipe outlets on the forested bank. It is postulated that the change is primarily due to a change in the amount of throughflow beneath the forest caused by an increase in evapotranspiration.

Irradiance formations of on-axis Lambertian pointlike sources in polygonal total-internal-reflection straight light pipes

Different geometric shapes of light pipes cause different irradiance distributions. We analytically explore the irradiance distributions of on-axis Lambertian pointlike sources in polygonal total-internal-reflection (TIR) straight light pipes. It is analytically shown that the irradiance of pentagonal light pipes concentrates on the center of the exit plane. Numerical verifications are also provided, and experimental explorations with different shapes of acrylic light pipes are carried out for comparison. We also analyze the influence of light-pipe length on distribution uniformity and deduce the smallest uniform-mixing length/circumradius ratios for polygonal light pipes.

3137 プラスチック射出成形金型の冷却管配置設計 : 3次元モデルへの適用(J03-3 解析・設計の高度化・最適化(3),J03 解析・設計の高度化・最適化)

We have proposed a new design method to optimize a cooling pipe shape in the three-dimensional space for plastic injection molding die by applying the response surface approach and shape optimization technique. To evaluate the optimality of cooling pipe arrangement and shape, cooling rate and temperature distribution in the die, which are primal factors to cause residual stresses producing some defects in the molded plastic, are used as objective functions. Then the cooling pipe shape and position to minimize the two objective functions simultaneously by using optimization techniques has been obtained. The proposed method has been applied to some cooling pipe shape design of 3-dimensional problem to discuss the availability off the method.

D24 ポンプゲート用軸流ポンプの動翼・案内翼形状および吸込み部形状に関する研究(D2 流体工学4)

D24 ポンプゲート用軸流ポンプの動翼・案内翼形状および吸込み部形状に関する研究(D2 流体工学4)

13世紀のヴィテルボの噴水に関する研究

Viterbo public fountains may be classified into three types: rectangular basin fountains (fontane a vasca rettangolare), cast fountains (fontane a fuso), and overlapping caps fountains (fontane a coppe sovrapposte). I measured multiple fountains structured in Viterbo during the 13th century to compare their shapes. The results of these measurements show that many apparent similarities exist in the basin and water pipe shapes used in rectangular basin fountains, cast fountains and overlapping caps fountains. The results from this research indicate that the fountain basins and water pipes structured in Viterbo in the 13th century were specifically designed to portray the important function of drawing water, even though the fountains were more commemorative than anything else.

테일 파이프 형상 개선을 통한 휠로더 캐빈 소음 저감 연구

In a wheel loader, the tail-pipe is installed at the exhaust tube of muffler for the reduction of exhaust noise and the cooling of engine room, however, the cabin noise level can be largely increased due to the tail-pipe. In this paper, to grasp and reduce the cabin noise, a series of noise and vibration tests were carried out in addition to numerical simulations. As a result, the transmission path of exhaust noise toward the cabin was exactly identified and the improved shape of tail pipe, that can reduce the cabin noise, was derived through various numerical simulations and real tests.

Effects of the UOE/UOC pipe manufacturing processes on pipe collapse pressure

Large-diameter pipes used in offshore applications are commonly manufactured by cold-forming plates through the UOE process. The plate is crimped along its edges, formed into a U-shape and then pressed into an O-shape between two semicircular dies. The pipe is welded closed and then circumferentially expanded to obtain a highly circular shape. Collapse experiments have demonstrated that these steps, especially the final expansion, degrade the mechanical properties of the pipe and result in a reduction in its collapse pressure upwards of 30%. In this study the UOE forming process has been modeled numerically using a 2-D finite element model. The model can assess the effects of press parameters of each forming step on the final geometry and mechanical properties of the pipe. The final step involves simulation of pipe collapse under external pressure in order to quantify the effect of the forming variables on its performance. Examples of these variables are the radii of the forming dies, the chosen displacements of the dies, the compression strain in the O-step, the expansion strain, etc. An extensive parametric study of the problem has been conducted, through which ways of optimizing the process for improved collapse performance have been established. For example, it was found that optimum collapse pressure requires a tradeoff between pipe shape (ovality) and material degradation. Generally, increase in the O-strain and decrease in the expansion strain improve the collapse pressure. Substituting the expansion with compression can not only alleviate the UOE collapse pressure degradation but can result in significant increases in collapse performance.

A model for stress-controlled pipe growth

The rock mechanics theory for deformation of underground mining excavations under high stress conditions can be used to explain the growth and geometry of volcanic pipes. In an underground excavation stress concentrates greatest on the sides of an excavation perpendicular to the principal vector of compression. If the stress is high enough fractures will develop causing scaling of the tunnel sidewalls and tunnel growth perpendicular to the principal vector of compression. Pre-existing structures aid the physical mechanisms of pipe growth such as gravitational collapse, explosive fragmentation and turbulent erosion; and by reducing the strength of the rock mass should also aid stress-induced scaling. Universal Distinct Element Code numerical modelling demonstrated in this study reproduces the stress conditions around a circular pipe under uniaxial compression and simulates pipe growth as wedges bounded by failed pre-existing joints form around the pipe and are “assimilated” into the pipe. The results show how a volcanic pipe will tend to grow perpendicular to the principal vector of compression if the internal magma pressure is low or absent. The orientations of the pre-existing joints affect the exact direction of pipe growth in a predictable manner. Examples from other publications demonstrate that the model is consistent even in extensional tectonic environments. Case studies from kimberlite occurrences in the Limpopo Belt, at Finsch Mine and the Gross Brukkaros Volcanic Complex demonstrate that dykes and magmatic bodies of kimberlite with high overpressures during emplacement normally have geometries trending near parallel to the principal vector of compression. Yet pipes or parts of pipes that underwent strong underpressures during emplacement (often ending up comprising fragmental volcaniclastic infill) have an elongation near perpendicular to the same vector. Thus the stress-induced pipe growth model is demonstrated to be important for some pipes. The study of volcanic pipe and dyke shapes can therefore be used to determine the stress regime at the time of emplacement, and to distinguish between kimberlite occurrences formed at different times within different stress tensors.

Numerical simulation of swirling flows in oxidation reactors for TiO 2 manufacture

The oxidation reactor plays a key role in producing rutile titanium dioxide (TiO 2) from vapor-phase titanium tetrachloride (TiCl 4) by employing a swirling flow operation for enhanced gas mixing. This work aims to understand the effect of reactor configuration on the 3-D swirling flow field using computational fluid dynamics (CFD) simulation. Considering the anisotropic turbulence involved, the Reynolds stress model is applied to describe the complex swirling flow together with the cross-flow mixing of gases. The results show significant effect of the flow angle between the wall jet of air stream (representing TiCl 4 in practice) and the axial direction on the initial flow field of cross-flow mixing, where 60° gives smooth profiles of axial velocity development while 90° may provide the fastest mixing between the jet and the axial bulk flow. The pipe shape for the reaction and developing zone, i.e., straight, expanding and shrinking, shows slight influence on the hydrodynamics.

Development of shape measurement system using an omnidirectional sensor and light sectioning method with laser beam scanning for Hume pipes

A shape measurement system for Hume pipes (diameter 1200 to 2000 mm) is developed using an omnidirectional sensor and a light sectioning method with laser beam scanning to evaluate degradation of Hume pipes. This system can measure the inner wall shape of Hume pipes at high speeds (about 3000 distance measurement points within 3 s) and high accuracy while moving along the pipe axis, and it can evaluate the corrosion quantity of the pipe wall surface. To measure the 3-D shape, the system is developed using an omnidirectional imaging device combined with a laser beam for slit light projection, and a hyperbolic mirror and high-precision digital camera. Also, an algorithm is developed that calculates position coordinates of the camera optical axis and posture with the distance data from the camera optical axis to the pipe wall surface. Performance test results of the developed system have accuracy in a shape measurement of about 3 mm for distances of 400 to about 1600 mm.