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1
Ao-kui, Xiong, et Wei Qing-ding. « The decay of swirling flows in a type of cross-section-varying pipes ». Applied Mathematics and Mechanics 22, no 8 (août 2001) : 983–88. http://dx.doi.org/10.1007/bf02436398.
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Kotorynski, W. P. « Dispersion in Pipes with Slowly Varying Cross-Sections ». SIAM Journal on Mathematical Analysis 25, no 3 (mai 1994) : 915–40. http://dx.doi.org/10.1137/s0036141090183730.
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Yu, Hao, Feng Liang, Yu Qian, Junjie Gong, Yao Chen et An Gao. « Phononic Band Gap and Free Vibration Analysis of Fluid-Conveying Pipes with Periodically Varying Cross-Section ». Applied Sciences 11, no 21 (8 novembre 2021) : 10485. http://dx.doi.org/10.3390/app112110485.
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Phononic crystals (PCs) are a novel class of artificial periodic structure, and their band gap (BG) attributes provide a new technical approach for vibration reduction in piping systems. In this paper, the vibration suppression performance and natural properties of fluid-conveying pipes with periodically varying cross-section are investigated. The flexural wave equation of substructure pipes is established based on the classical beam model and traveling wave property. The spectral element method (SEM) is developed for semi-analytical solutions, the accuracy of which is confirmed by comparison with the available literature and the widely used transfer matrix method (TMM). The BG distribution and frequency response of the periodic pipe are attained, and the natural frequencies and mode shapes are also obtained. The effects of some critical parameters are discussed. It is revealed that the BG of the present pipe system is fundamentally induced by the geometrical difference of the substructure cross-section, and it is also related to the substructure length and fluid–structure interaction (FSI). The number of cells does not contribute to the BG region, while it has significant effects on the amplitude attenuation, higher order natural frequencies and mode shapes. The impact of FSI is more evident for the pipes with smaller numbers of cells. Moreover, compared with the conventional TMM, the present SEM is demonstrated more effective for comprehensive analysis of BG characteristics and free vibration of PC dynamical structures.
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Xijie, Liu, Sami Ainane et Yap Yit Fatt. « Modeling of liquid-solid flow erosion in curved pipes of gradually varying cross section ». Journal of Physics : Conference Series 1276 (août 2019) : 012028. http://dx.doi.org/10.1088/1742-6596/1276/1/012028.
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LUCHINI, PAOLO, et FRANÇOIS CHARRU. « Consistent section-averaged equations of quasi-one-dimensional laminar flow ». Journal of Fluid Mechanics 656 (1 juillet 2010) : 337–41. http://dx.doi.org/10.1017/s0022112010002594.
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Section-averaged equations of motion, widely adopted for slowly varying flows in pipes, channels and thin films, are usually derived from the momentum integral on a heuristic basis, although this formulation is affected by known inconsistencies. We show that starting from the energy rather than the momentum equation makes it become consistent to first order in the slowness parameter, giving the same results that have been provided until today only by a much more laborious two-dimensional solution. The kinetic-energy equation correctly provides the pressure gradient because with a suitable normalization the first-order correction to the dissipation function is identically zero. The momentum equation then correctly provides the wall shear stress. As an example, the classical stability result for a free falling liquid film is recovered straightforwardly.
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Ključanin, Dino, et Abaz Manđuka. « The cantilever beams analysis by the means of the first-order shear deformation and the Euler-Bernoulli theory ». Tehnički glasnik 13, no 1 (23 mars 2019) : 63–67. http://dx.doi.org/10.31803/tg-20180802210608.
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The effect of the Timoshenko theory and the Euler-Bernoulli theory are investigated in this paper through numerical and analytical analyses. The investigation was required to obtain the optimized position of the pipes support. The Timoshenko beam theory or the first order shear deformation theory was used regarding thick beams where the shearing effect of the beam is considered. The study of the thin beams was performed with the Euler-Bernoulli theory. The analysis was done for stainless steel AISI-440C beams with the rectangular cross-section. The steel beams were a cantilever and stressed under varying point-centred load.
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JANG, DONG SOO, EUN-JI LEE, SANG HUN LEE et YONGCHAN KIM. « THERMAL PERFORMANCE OF FLAT PLATE PULSATING HEAT PIPES WITH MINI- AND MICROCHANNELS ». International Journal of Air-Conditioning and Refrigeration 22, no 04 (décembre 2014) : 1450025. http://dx.doi.org/10.1142/s2010132514500254.
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This study presents the thermal performance of pulsating heat pipes (PHPs) using distilled water with mini- and microchannels. The PHPs were fabricated with the channels of square cross section which had hydraulic diameters ranged from 1.6 to 3.2 mm in minichannels and from 0.714 to 0.941 mm in microchannels. The performance of the PHPs was measured and analyzed by varying hydraulic diameter, number of turns, filling ratio, and input power. The filling ratio of the working fluid varied from 0% to 100%. The input power was controlled in the range between 3.6 and 150 W. The hydraulic diameter, number of turns, filling ratio, and input power showed strong influence on the performance of the PHP. In the PHP models with mini- and microchannels, optimum working conditions, such as filling ratio and heat input, were quite different according to channel size.
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Trykoz, L. V., S. M. Kamchatnaya, O. M. Pustovoitova et A. O. Atynian. « The Investigation of Prestressed Pressure Pipes, Reinforced with Fiberglass Plastic ». International Journal of Engineering Research in Africa 36 (juin 2018) : 1–11. http://dx.doi.org/10.4028/www.scientific.net/jera.36.1.
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The problem of a combined action of reinforced concrete pipe and fiberglass safety cage. The prestressed cage not only decreases deformability of a pipe under load but protects the material of a pipe from agressive external factors. The process of force transfer from concrete pipe and fiberglass has been analyzed and the equation of stress and deformation for pipes and fiberglass has been deduced. It is shown that stress in fiberglass does not remain constant varying wall thickness, reducing towards the concrete core. Hoop stresses in the concrete core increase towards the centre of a pipe. Unlike known solutions the performed calculations take into account the performance of both layers – concrete and fiberglass. The total stresses in a concrete pipe in the most dangerous section from internal pressure and the reduction by fiberglass winding have been determined. The results obtained in the given work provide with the possibility of modelling long-term properties of composite reinforced concrete constructions and optimization of winding angle of fiberglass casing depending on the diameter of a pipe, tension force and the quantity of reinforcing filler.
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Verbanck, Michel A. « Assessment of sediment behaviour in a cunette-shaped sewer section ». Water Science and Technology 33, no 9 (1 avril 1996) : 49–59. http://dx.doi.org/10.2166/wst.1996.0174.
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The accumulation of deposits in sewers causes widespread concerns of either operational or environmental nature. It is believed that a number of sediment-related nuisances can substantially be controlled in adapting the characteristics of sewer pipes as a function of local constraints and circumstances. In particular, key design parameters such as cross-section shape or hydraulic roughness of inner walls are currently selected basing more on empiricism and intuition than on full knowledge of the sediment transport driving processes. A valid track for optimization of these parameters is to run mathematical simulations of the sediment transport behaviour under varying design scenarios. This option, however, supposes that a robust mathematical procedure to compute sediment transport capacity in sewers is available, embracing all primary physical factors of influence. Starting from a theoretical description of shear turbulence suggested by Bagnold (1966), a suspension formula is developed dedicated to the specific sewer flow properties. Applying this formula to the case of a main sewer presenting a composite cross-section allows to illustrate how geometrical discontinuities influence sediment transport characteristics in real conduits.
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Kasivisvanathan, S. R., P. N. Kaloni et K. R. Rajagopal. « Flow of a non-newtonian fluid through axisymmetric pipes of varying cross-sections ». International Journal of Non-Linear Mechanics 26, no 5 (1991) : 777–92. http://dx.doi.org/10.1016/0020-7462(91)90028-r.
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Bobyleva, T., et A. Shamaev. « Optimization Problems Arising from the Design of Pipes Made of Composite Materials ». Materials Science Forum 992 (mai 2020) : 1024–29. http://dx.doi.org/10.4028/www.scientific.net/msf.992.1024.
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The work is devoted to the construction of analytical solutions for the stress-strain state of a cylindrical hollow elastic rod with a layered structure along the radius. Earlier, the problem of finding the stress-strain state of a rod of composite material fixed at one end with the applied forces and moments of forces at the other end was considered. An approximate representation of the solutions was given, which included auxiliary problems on one fragment of the cylinder, consisting of periodically repeating similar fragments. Such auxiliary problems in the general case do not have an analytical solution. In this paper it is shown that in the presence of radial symmetry of the rod section, it is possible to construct a stress-strain state in an analytical form. In addition, tensile and bending stiffness can be presented in an analytical form. The latter circumstance allows us to set a problem of optimizing the stiffness characteristics of a rod with its fixed weight. Optimization is carried out by varying the thickness of the layers of the same materials.
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Kim, Taesik, Suleyman Deveci, Inmo Yang, Bob Stakenborghs et Sunwoong Choi. « Visual, Non-Destructive, and Destructive Investigations of Polyethylene Pipes with Inhomogeneous Carbon Black Distribution for Assessing Degradation of Structural Integrity ». Polymers 14, no 5 (7 mars 2022) : 1067. http://dx.doi.org/10.3390/polym14051067.
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Carbon black (CB) is used in polyethylene (PE) pipes to protect against thermal and photooxidation. However, when CB is not properly dispersed in the PE matrix during processing, white regions having little or no CB concentration, known as “windows,” appear within the CB/PE mixed black compound. In some cases, windows can drastically affect the structural integrity of both the pipe and butt fusion joint. In this work, PE pipes with varying amounts of windows were investigated for their characteristic window patterns, as well as quantifying the area fraction of windows (% windows). Tensile test on specimens with known % windows determined a critical limit above which the fracture strain rapidly degrades. Micro-tensile and micro-indentation results showed tear initiation at the window–black PE matrix boundary; however, they did not confirm the mechanism of tear initiation. In support of this work, a method of making thin shavings of a whole pipe cross section was developed, and the best viewing windows under cross-polarized monochromatic light were identified. In addition, a phased array ultrasonic test (PAUT) and microwave imaging (MWI) were directly applied to the pipe and confirmed the presence and patterns of the windows.
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Bondarev, Edward, Igor Rozhin et Kira Argunova. « Problem of conjugate heat transfer between main gas pipeline and frozen ground ». E3S Web of Conferences 102 (2019) : 01001. http://dx.doi.org/10.1051/e3sconf/201910201001.
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Mathematical model of non-isothermal gas flow within the framework of tube hydraulics including change of tube cross-section due to hydrate formation and the dependence of coefficient of heat transfer between gas and hydrate layer on varying flow area is proposed. The corresponding conjugate problem of heat exchange between imperfect gas in the pipeline and the environment is reduced to the solution of differential equations describing non-isothermal flow of gas in pipes and heat transfer equations in ground with the corresponding conjugation conditions. In the quasi-stationary mathematical model of hydrate formation (dissociation), the dependence of gas-hydrate transition temperature on gas pressure is taken into account. Some decisions taken in the design of the first section of the main gas pipeline «Power of Siberia» have been analyzed. It has been shown that if gas is not sufficiently dried, outlet pressure may drop below the technological limit in about 6-7 hours. At the same time, for completely dry gas ,it is possible to reduce the cost of thermal insulation of the pipeline at least two fold.
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Baptista, Nishida, Larissa Krambeck, Dos Dias et Alves Antonini. « Experimental investigation of heat pipe thermal performance with microgrooves fabricated by wire electrical discharge machining ». Thermal Science 24, no 2 Part A (2020) : 701–11. http://dx.doi.org/10.2298/tsci180227206b.
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This work presents the use of electrical discharge machining (EDM) technology for manufacturing of three different types of axial microgrooves in heat pipes. This specific process, called wire electrical discharge machining (wire-EDM), allows the fabrication of microgrooves on the inner wall of a heat pipe with accuracy. Different from other capillary structures, such as composite wick and screen mesh, the material is removed from the pipe?s container in order to conceive the capillary structure, which contributes with the mass reduction of the passive two-phase heat transfer device. The heat pipes were manufactured from a straight copper pipe with the external diameter of 9.45 mm, the inner diameter of 6.20 mm, and a total length of 200 mm. Three types of axial microgrooves were manufactured for constant width (35 ?m) and varying the depth (from 30-48 ?m), and thickness (from 35-70 ?m). The number of microgrooves was also varied from 21-32 microgrooves. Water was used as the working fluid and the loading filling ratio was 60% of the evaporator volume. The condenser was cooled by air forced convection, the adiabatic section was insulated and the evaporator was heated by an electrical resistor and it was insulated from the environment with aeronautic thermal insulation. The thermal performance of the heat pipes are analyzed based on experimental results, so the heat pipes were tested at the horizontal and different inclinations under different low heat loads (from 5-50 W or a heat flux from 0.21-2.10 W/cm2). The experimental results showed that the axial microgrooves manufactured by the wire-EDM process worked satisfactorily in all analyzed cases and microgrooves of Type 1 showed a better thermal performance when compared with the others.
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Kuo, Chi-Wei, et C. Steve Suh. « On the Dispersion and Attenuation of Guided Waves in Tubular Section with Multi-Layered Viscoelastic Coating — Part I : Axial Wave Propagation ». International Journal of Applied Mechanics 09, no 01 (janvier 2017) : 1750001. http://dx.doi.org/10.1142/s1758825117500016.
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Guided modes admissible in elastic hollow pipes are derived to establish their dispersion and attenuation characteristics in the presence of multi-layered viscoelastic coatings. Longitudinal waves propagating in the axial direction in response to displacement continuity boundary conditions signifying perfect interfacial bonds are evaluated against a baseline uncoated tubing. Viscoelastic bitumen and epoxy are coating materials applied to improve pipeline reliability. The impact of viscoelastic coating layers on wave dispersion and attenuation are investigated by incorporating complex material properties in the characteristic equation. The real and complex roots of the corresponding characteristic equation are determined, allowing the phase velocity and attenuation dispersion to be depicted as functions of the propagation frequency. The effects of varying attenuation parameter and coating thickness are also examined. Viscoelastic protective materials are found to have a substantial impact on the propagation and attenuation of longitudinal waveguide modes.
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Li, Shuanglong, Limin Wei, Xiaobin Chen et Qun He. « Numerical Investigation on Dynamic Performance of a Bridge-Tunnel Transition Section with a Deep Buried Pile-Plank Structure ». Advances in Civil Engineering 2020 (29 septembre 2020) : 1–16. http://dx.doi.org/10.1155/2020/8885535.
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To address the track irregularity at transition zones between subgrade and rigid structures (bridge, tunnel, etc.), some common transition approaches, such as trapezoid subgrade, were adopted in many engineering areas. However, in regard to a mountainous area, the common transition approaches may not be practicable anymore due to the limitation of the length between subgrade and rigid structures. In this paper, a new type of bridge-tunnel transition section with a deeply buried pile-plank structure (DBPPS) for short-distance transition is introduced. A three-dimensional finite element model that considers vehicle-track-subgrade coupling vibration is proposed to study the dynamic performances of a DBPPS transition section in the Shanghai–Kunming high-speed railway. With this model that has been validated with measured responses from field tests, the dynamic responses and the smoothness in track stiffness along the transition zone are analyzed. In addition, the influences of train speed, axle load, and train direction on dynamic responses are investigated, and the influences of two optimization strategies, including varying-length piles and constant-length piles, on the stiffness smoothness of the DBPPS transition section are discussed. Results show that the vibration level of the DBPPS transition section is lower than that of the abutment and the tunnel, and the additional load caused by vertical track stiffness difference aggravates the vibration at the connections between the DBPPS transition section and the abutment (or tunnel). Furthermore, the smoothness in stiffness along the transition zone can be significantly improved by the improvement strategy with varying-length piles.
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Sukadana, Ida Bagus Putu. « UJI VISUAL THERMOGRAPHY PADA OSCILLATING HEAT PIPE ». JTT (Jurnal Teknologi Terapan) 5, no 1 (17 mai 2019) : 21. http://dx.doi.org/10.31884/jtt.v5i1.163.
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Oscillating Heat Pipes one of the new family of heat pipe is two-phase heat transfer technologies with excellent performance capabilities, simple structure and low production costs. As one of the non-intrusive method in temperature measurement, thermography observation in OHP still very rarely to use although the result was able to explain the relation between temperature oscillation and fluidic motion of fluid. Furthermore this paper aims to study the behavior of thermal profile with the thermography observation. Water with filing ratio (45%) has been chosen as the working fluid for the close loop OHP. The heating power was varying into the evaporator section of OHP from 12 until 142 Watt. It was found that thermography observation very useful tools to define internal flow pattern inside OHP channel. Intermittent oscillation, circulation and dry-out phenomenon was captured more better than conventional temperature measurement. The lowest thermal resistance was found 0.234 °C/W corresponding with 3210 Watt/mK effective thermal conductivity at heat input 142 Watt.
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Tran, Khiem T., Scott J. Wasman, Michael McVay et Rodrigo Herrera. « Capacity evaluation of voided driven piles using embedded data collectors ». Canadian Geotechnical Journal 54, no 10 (octobre 2017) : 1397–407. http://dx.doi.org/10.1139/cgj-2017-0008.
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This paper presents an application of a method that will be implemented in the embedded data collector (EDC) system in the near future, to estimate the capacity of driven piles with a combined solid and voided cross section. Data from accelerometers and strain gauges located in the solid sections at both the top and the bottom of a pile are used to independently estimate the pile’s skin friction and tip resistance. Wave propagation along the pile is modeled as a one-dimensional wave equation, with a nonuniform cross section and with nonlinear static skin friction and viscous-damping soil resistances acting along multiple segments of the pile. The static skin friction is extracted by least-squares fitting of computed particle velocities with measured data at both the top and the bottom of the pile. The pile tip is modeled as a nonlinear single degree of freedom with viscous damping. Static tip resistance (nonlinear stiffness–displacement relationship) is extracted by least-squares fitting of the predicted total force and energy with the measured tip data. The new EDC method was applied to four combined solid–voided cross section driven piles with capacities varying from 2800 to 6700 kN. The results of the data evaluated with the new EDC method are consistent with those from the static load tests to within 15%.
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UEHIGASHI, Atsushi, Shigeki SUGIURA, Koji MORINISHI et Nobuyuki SATOFUKA. « Numerical Investigation Using Compressible Navier-Stokes Equations for Low-Speed Flow in Pipes with Varying Cross Sections ». JSME international journal. Ser. 2, Fluids engineering, heat transfer, power, combustion, thermophysical properties 35, no 4 (1992) : 507–12. http://dx.doi.org/10.1299/jsmeb1988.35.4_507.
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Figliuzzi, B., et C. R. Buie. « Rise in optimized capillary channels ». Journal of Fluid Mechanics 731 (14 août 2013) : 142–61. http://dx.doi.org/10.1017/jfm.2013.373.
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AbstractMany technological applications rely on the phenomenon of wicking flow induced by capillarity. However, despite a continuing interest in the subject, the influence of the capillary geometry on the wicking dynamics remains underexploited. In numerous applications, the ability to promote wicking in a capillary is a key issue. In this article, a model describing the capillary rise of a liquid in a capillary of varying circular cross-section is presented. The wicking dynamics is described by an ordinary differential equation with a term dependent upon the shape of the capillary channel. Using optimal control theory, we were able to design optimized capillaries which promote faster wicking than uniform cylinders. Numerical simulations show that the height of the rising liquid was up to 50 % greater with the optimized shapes than with a uniform cylinder of optimal radius. Experiments on specially designed capillaries with silicone oil show a good agreement with the theory. The methods presented can be useful in the design and optimization of systems employing capillary-driven transport including micro-heat pipes or oil extracting devices.
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Burg, Patrik, Tomáš Vítěz, Jan Turan et Jana Burgová. « Evaluation of Grape Pomace Composting Process ». Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 62, no 5 (2014) : 875–81. http://dx.doi.org/10.11118/actaun201462050875.
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The paper deals with the problems of composting of grape pomace in strip compost piles. The three variants of compost piles formed from grape pomace and vegetables waste, wood chips and mature in varying proportions were tested. Turning of piles was performed using windrow turner PKS 2.8, in which the achieved performance was monitored. On the performance of windrow turner has a significant influence also cross section or width and height of turning piles and the bulk density of ingredients including their moisture. In evaluating, attention has been paid to assessment of selected parameters (temperature, moisture content) of the composting process. From the viewpoint of temperature course, the highest temperature reached at the piles in Var. I (64.1 °C) and Var. II (55.3 °C). Moisture of compost piles in the individual variants did not differ significantly and ranged between 25–35%.
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Libreros, Jose, et Maria Trujillo. « Effects of Mesh Generation on Modelling Aluminium Anode Baking Furnaces ». Fluids 6, no 4 (4 avril 2021) : 140. http://dx.doi.org/10.3390/fluids6040140.
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Anode baking is critical in carbon anode production for aluminium extraction. Operational and geometrical parameters have a direct impact on the performance of anode baking furnaces (ABF), and hence on the resulting anode quality. Gas flow patterns, velocity field, pressure drop, shear stress and turbulent dissipation rate are the main operational parameters to be optimised, considering a specific geometry that is discretised as a mesh. Therefore, this paper aims to establish the need to generate an appropriate mesh to perform accurate numerical simulations of three-dimensional turbulent flow in a single section of an ABF. Two geometries are considered for generating three meshes, using COMSOL and cfMesh, with different refinement zones. The three meshes are used for creating nine incompressible isothermal turbulent flow models, with varying operational parameters. Velocity field, convergence and turbulent viscosity ratio in the outlet of fuel inlet pipes are the quantification criteria. Quantification criteria have shown that a better physical representation is obtained by refining in the whole combustion zone. COMSOL Multiphysics’ built-in mesh generator allows quadrilateral, tetrahedron and hexahedron shapes. Adaptive cell sizes and shapes have a place within modelling, since refining a mesh in appropriate zones brings the Peclet number down when the incompressible isothermal turbulent flow is simulated.
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Kanarska, Yuliya, et Otis Walton. « Application of parallel distributed Lagrange multiplier technique to simulate coupled Fluid-Granular flows in pipes with varying Cross-Sectional area ». Powder Technology 291 (avril 2016) : 35–45. http://dx.doi.org/10.1016/j.powtec.2015.11.062.
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Lee, SangGu, SiHun Lee, SangJoon Shin, Youdan Kim et Soogab Lee. « Pressure mode analysis of nonuniform cross-sectional pipes and preliminary evaluation of a pogo suppressor ». Proceedings of the Institution of Mechanical Engineers, Part G : Journal of Aerospace Engineering 233, no 12 (8 janvier 2019) : 4447–56. http://dx.doi.org/10.1177/0954410018823627.
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The pogo phenomenon is a type of instability that arises when the longitudinal modes of a space launch vehicle fuselage resonate with the pressure modes of the feedline in its propulsion system, with such resonance re-exciting the fuselage structure. To analyze this phenomenon, this paper specifically focuses on an analysis of the pressure modes in the space shuttle interpump line included in the LOX engine system. Because the interpump line is connected to pipes in different cross-sectional areas, the pressure modes are analyzed as a nonuniform cross-sectional pipe. Further, by applying a pogo suppressor in the feedline system, the possibility of preventing the pogo phenomenon is demonstrated. In order to design the suppressor, the resistive accumulator inertance, compliance, and resistance are considered as variables. Resistive accumulator compliance and inertance are determined and the pressure perturbation of the engine is prevented by lowering the inlet pressure amplitude of the high-pressure oxidizer pump (HPOP) in the space shuttle LOX system interpump line. When the resistive accumulator resistance is increased, the pressure frequencies of the interpump line gradually decrease, avoiding the resonance region with the fuselage. As a result, the resonance region with the fuselage is prevented by varying the pressure amplitude and natural frequencies of the interpump line. In this way, the capability of the present pogo suppression is evaluated.
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Cattani, L., L. Pagliarini, F. Bozzoli, M. Mameli, S. Filippeschi, M. Marengo, L. Pietrasanta, N. Miché et D. Mangini. « Estimation of the local instantaneous heat flux inside a pulsating heat pipe for space applications ». Journal of Physics : Conference Series 2444, no 1 (1 février 2023) : 012010. http://dx.doi.org/10.1088/1742-6596/2444/1/012010.
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Abstract Pulsating Heat Pipes (PHP) are promising and effective passive two-phase heat transfer devices in terms of high heat transfer capability, efficient thermal control, adaptability and low cost and therefore they have been extensively studied in the last years. Many authors have estimated the heat fluxes at the evaporator and at the condenser area only in terms of the average values based on first principle considerations. In the present study the application of an inverse analysis technique to experimental infrared temperature data is proposed to investigate the local convective heat flux for forced convection flow inside these devices along the adiabatic zone. A PHP specifically designed to be hosted on board the heat transfer host of the International Space Station was tested in microgravity during the 67th Parabolic Flight Campaign organized by the European Space Agency. The device consists of an aluminium tube closed in a loop with 14 turns in the evaporator section, 3 mm inner diameter, half filled with FC-72 fluid. The external temperatures of the device are measured in the adiabatic zone with a high-speed infrared camera (50 Hz, 1280x1024 pixels). The images are thereafter post-processed and adopted as input data for the solution of the inverse heat conduction problem in the pipe wall (Tikhonov regularisation method) to extrapolate time-varying local heat fluxes on the tube internal surface in contact with the fluid.
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Lukjanova, Aljona, et Malle Mandre. « Anatomical structure and localisation of lignin in needles and shoots of Scots pine (Pinus sylvestris L.) growing in a habitat with varying environmental characteristics ». Forestry Studies / Metsanduslikud Uurimused 49, no 1 (1 janvier 2008) : 37–46. http://dx.doi.org/10.2478/v10132-011-0061-2.
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Anatomical structure and localisation of lignin in needles and shoots of Scots pine (Pinus sylvestrisL.) growing in a habitat with varying environmental characteristicsWe investigated the influence of a habitat with varying environmental characteristics on the anatomical structure and localisation of lignin in needles and shoots of Scots pine (Pinus sylvestrisL.). A dune in South-West Estonia was chosen as the study area because it has extreme environmental characteristics: primitive sandy soil, deficiency of water, heavy winds and high light exposure. Analysis showed that the needles of all age and the current-year shoots of pines growing on the foot of the dune had the largest average cross section, mesophyll and parenchyma areas. The degree of the lignification of needles at the foot, on the slope and on the top of the dune differed distinctly. Intensive lignification of the cellular walls of the xylem was observed in needles and shoots of the pines, growing at the foot, but not in the trees growing on the top of the dune. Analysis showed that the anatomical structure and localisation of lignin, both in needles and in shoots, depend on their age, the trees location (foot, slope or top of the dune) and soil mineral composition.
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Bailey, Breanna, et Sidiq A. Osomo. « Prediction of Nominal Compressive Strength in Steel Piles Subject to Corrosion Losses : A Finite Element Approach ». Journal of Civil Engineering and Construction 9, no 1 (15 février 2020) : 24–30. http://dx.doi.org/10.32732/jcec.2020.9.1.24.
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This paper presents a method for predicting the nominal compressive strength of steel I-shaped piles subject to cross-sectional losses caused by corrosion. The method requires a finite element linear buckling analysis of the corroded cross-section. Results from the finite element buckling analysis may be integrated into design capacity equations contained in the 15th edition of the American Institute of Steel Construction Steel Construction Manual. Non-linear post-buckling analyses were used to verify the accuracy of the proposed method. Three cross-sectional geometries (W14x82, W14x90, and W14x120) were analyzed at varying degrees of cross-sectional loss. Results show close agreement between the non-linear finite element analyses and the proposed method of calculating nominal compressive strength.
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Haque, Md Enamul, Md Efthakher Hossain et Mohammad Mashud. « Performance Analysis of a Heat Pipe with Stainless Steel Wick ». Journal of Engineering Advancements 01, no 01 (avril 2020) : 16–22. http://dx.doi.org/10.38032/jea.2020.01.004.
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In this study, the influences of different parameters on performance of a heat pipe with stainless steel net as wick have been presented. Experiments have been carried out for an input power range from 80 W to 160 W, constant cooling water mass flow rate of 0.0515 liter/s, and constant temperature at the inlet to condenser of 11°C. The temperatures were recorded at different power level by using a laser thermometer of the heater block, evaporator and condenser end at 50 second interval. Variation in the input power was done by varying the input voltage. It was done by a variack. Considering all criteria the copper is selected as the material of the container, water is selected as the working fluid of the heat pipe, stainless steel net is used as wick material. As copper/water heat pipes are able to tolerate storage temperatures between -65°C and 250°C, and can effectively operate between 10°C and 250°C. So a .9144 m copper tube is used to construct the heat pipe. Inside this tube stainless steel net is used as wick material to aid the flow of fluid. In the observation it is observed that the temperature of the evaporator end increases at a greater rate of the copper pipe than the heat pipe at different power level. It has been shown the variation of temperature of the heater block and the evaporator section at 80V, 100V, 120V, 140V, 160V respectively of the heat pipe and copper pipe.
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Peng, Yishu, Ruidong Yang, Tao Jin, Jun Chen et Jian Zhang. « Potentially toxic metal(loid) distribution and migration in the bottom weathering profile of indigenous zinc smelting slag pile in clastic rock region ». PeerJ 9 (7 avril 2021) : e10825. http://dx.doi.org/10.7717/peerj.10825.
Texte intégralRésumé :
Background There are contaminated by potentially toxic metal(loid)s (PTMs) that the surface soil and the weathering profiles around the indigenous zinc smelting slag piles or smelters in the smelting area. However, few systematic studies are currently focusing on the PTM distribution and migration among the slag and its bottom weathering profile. Methods This research determined the concentrations of PTMs and pH values. And we analyzed PTM distribution in the two weathering profiles (slag-covered and slag-absent) with a small horizontal distance in the clastic rock region in the smelting area. Results The soil As and Pb contents, respectively, within the 30 and 50 cm depth in the slag-covered section were higher than those in the slag-absent profile. All soil Cd and Zn contents of the slag-covered core were significantly higher than those in the slag-absent weathering section. Conclusions Compared with the slag-absent weathering section, some PTMs (i.e., As, Cd, Pb and Zn) in the bottom weathering profile were polluted by these elements in the covered slag in the clastic rock region, and their depths were influenced by the slag to varying degrees. Additionally, with time, some PTMs (especially Cd and Zn) of the slag might finally contaminate the groundwater by leaching and infiltration through its bottom weathering profile in the clastic rock region.
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Yang, Yongqing, Guowei Li, Na Luo et Xueshan Cao. « Testing of Structural Integrity of U-Shaped Sheet Pile in Canal Engineering Using Ground Penetrating Radar ». Applied Sciences 12, no 22 (14 novembre 2022) : 11558. http://dx.doi.org/10.3390/app122211558.
Texte intégralRésumé :
Compared with other piles with the same cross-sectional area, “U-shaped” structural section sheet pile can increase the moment of inertia of the structure’s section. Due to the large excavation depth of the open section of the “Yin Jiang Ji Huai” river canal project in Anhui province, China, the unprotected excavated inclined canal slope covers a large land area, which results in the current situation of high housing demolition costs and a shortage of land resources in densely populated areas. In this study, the non-destructive testing of a U-shaped sheet-pile wall to protect the vertical slope of the underwater expansive soil in the canal project is studied, which is of great significance in reducing the construction area and minimizing the cost of construction. It is necessary to test the structural integrity of the U-shaped sheet pile, which is also vital to ensuring the whole project quality. Ground penetrating radar (GPR) is used to detect the structural integrity of the U-shaped sheet pile in expansive soil. On the basis of identification and conversion of the original GPR data format, the processing methods based on the time-varying automatic gain and wavelet analysis are implemented. This case study proves that the GPR testing method is effective to estimate the quality of the U-shaped sheet pile.
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Ness, O. B., et R. Verley. « Strain Concentrations in Pipelines With Concrete Coating ». Journal of Offshore Mechanics and Arctic Engineering 118, no 3 (1 août 1996) : 225–31. http://dx.doi.org/10.1115/1.2828838.
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This paper concerns the strain distribution, and in particular strain concentration in field joints, for concrete-covered pipelines during laying. A semi-analytical model, full-scale tests to verify the model, and results of a parameter study are described. The model is used to establish nonlinear moment-curvature curves at a number of cross sections on the concrete-coated pipe and in the field joint (FJ). These are used to establish a strain concentration factor (SCF) for the FJ, or characteristics for a varying stiffness model of a pipe for direct use in lay analyses. Constant moment, four-point bending tests have been conducted on 16-in and 20-in dia, concrete-coated pipes as well as material tests on the pipe steel, corrosion coating and concrete. The behavior of the pipe, and in particular the SCF at the field joints, is investigated and compared to predictions using the semi-analytical model. The model is found to give a good prediction of the SCF and strain distribution along the pipe joint, for both the steel and the concrete, and is suitable for use in lay analyses for the overbend of S-mode lay vessels.
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Skjelbreia, Lars. « THE CLAMP-ON WAVE FORCE METER ». Coastal Engineering Proceedings 1, no 7 (29 janvier 2011) : 39. http://dx.doi.org/10.9753/icce.v7.39.
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Because of the tremendous increase in offshore activities, a great effort has been made on obtaining information on wave forces on structural members. Several oil companies have invested large sums of money in the design and construction of full-scale systems for measuring the wave forces. The equipment used for measuring the forces have been single cantilevers or segmented piles designed to make discrete measurements along the pile. For instance, during the last five years, The California Company and California Research Corporation (subsidiaries of Standard Oil Company of California) operated an installation in the Gulf of Mexico with four segmented piles of different diameters. The wave forces were measured by three-foot high force dynamometers located at seven different elevations along the length of each test pile. Each dynamometer was constructed from a section of the cylindrical pile which was attached to a system of flexures on the inside. So far the wave forces have been measured on cylindrical piles varying in diameter from one to four feet and in water depths varying from 30 to 50 feet. As the pile diameter and water depth increase, however, the measurements of wave forces by use of a cantilever or a segmented pile become very difficult and expensive. Therefore, a need exists for investigating other means for measuring the wave forces on a pile. This paper will describe the design and operation of a force meter that may be clamped to an existing pile. In Spring 1960, California Research Corporation installed equipment incorporating eight of the clamp-on meters on an oil well drilling platform in the Gulf of Mexico. The water depth at the location is 100 feet, and two years of operation are planned.
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Ptaszyński, Bogusław, Rafał Łuczak, Zbigniew Kuczera et Piotr Życzkowski. « Influence of Local Gas Sources with Variable Density and Momentum on the Flow of the Medium in the Conduit ». Energies 15, no 16 (11 août 2022) : 5834. http://dx.doi.org/10.3390/en15165834.
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In this article, the analysis of mechanical energy changes in a gas medium flow with stable and variable density was presented. To determine the energy losses, the various sources of momentum and mass were used, which had an influence on air flow through the conduit in the system without heat exchange with the environment. The occurrence of varying density gas flow in the conduit (caused by local inflow of mass and momentum) in inclined pipes generates a natural depression–internal mechanical energy. The local momentum sources can facilitate or hinder the gas flow through the conduit. This phenomenon often appears in the network of underground mine workings and in ventilation and air conditioning installations. The characteristic for gas flow through a pipe or mining excavation is the equivalent aerodynamic resistance, the value of which is influenced by the mass and momentum of local sources. This value determines the facilitation or difficulty in gas transport through a section of conduit in relation to the mass stream of the medium. In this article, the dependency of mass flow and gas momentum with different densities on the value of the gas medium flow resistance in the conduit was analyzed. On the basis of the obtained results, the loss of mechanical energy and energy efficiency of flows were determined. In this work, two cases of fan work in suction and blowing modes were analyzed. For these examples, a gas inflow with three different mass streams, a density higher than the main stream density, and with a zero momentum value for this stream was modeled. Ten cases of mass inflow sources were considered. The results of the gas mass flow calculation through the fan m˙w and gas m˙0 and the coefficient of transport efficiency are graphically presented in the paper.
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SINGH, M., D. LIEPSCH, JOYCE McLEAN et G. PALLOTTI. « FLOW VISUALIZATION IN RIGHT CORONARY ARTERY BYPASS MODELS ». Journal of Mechanics in Medicine and Biology 08, no 03 (septembre 2008) : 293–315. http://dx.doi.org/10.1142/s021951940800270x.
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It is well known from fundamental fluid mechanics that separation regions occur at bends and bifurcations of blood vessels. In addition to this, a secondary flow is also created. This means that the flow is moving forward like a vortical plait. Vortices are created that move counterclockwise to each other perpendicular to the mainstream direction. Three-dimensional flow exists, which is totally different to the well-known parabolic flow in straight pipes under laminar flow conditions. Therefore, a short fundamental introduction to biofluid mechanics is presented in this paper. A coronary artery model with different bypasses is shown as an example. The coronary artery is a prominent cardiac vessel often affected by the atherosclerosis process, which can lead to its full blockage. Blood flow is restored by the construction of a bypass performed by implanting part of the saphenous vein. This bypass is subjected to varying flow conditions during the various phases of pulsatile blood flow. For precise location of the regions associated with flow abnormalities, flow visualization through the complete bypass, covering the arterial and bypass sections, is required. This forms the objective of the present work: to visualize flow changes in bypass models of the right coronary artery prior to its bifurcation under pulsatile flow conditions.
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Vittorini, Diego, Alessio Antonini, Roberto Cipollone et Roberto Carapellucci. « Multi-Variable Control and Optimization Strategy for Domestic Solar-ORC Combined Heat and Power Generation System ». E3S Web of Conferences 197 (2020) : 08014. http://dx.doi.org/10.1051/e3sconf/202019708014.
Texte intégralRésumé :
The feasibility of a solar-ORC system for domestic combined heat and power generation (CHP) is deeply affected by both the time-varying ambient conditions (e.g. solar irradiance, temperature, wind speed) and the thermal and electrical load profiles variability of the final application. The definition of a proper control strategy is proven to be a major design-challenge for successful operation of solar-ORC systems, with the main goal of assuring that the thermal power demand for space heating and Domestic Hot Water (DHW) production and the electricity needs are simultaneously satisfied. The rising demand for energy-autonomous systems also calls for the inclusion of a storage system within the base-layout, that could assure the electricity demand is properly matched after sunset or in very-low irradiance conditions, such as cloudy days. A comprehensive model accounts for the dynamic of the plant-integrated unit, featuring an ORC-based plant that bottoms a flat plate solar thermal collector: a parametric study is presented, and an off-design analysis is performed to properly assess the energy performance of the system. The heat availability to the ORC heat exchanger is evaluated, based on solar availability, thermal losses in the pipes and plant requirements, in terms of operating temperature and pressures and organic fluid mass flowrate. R245fa is selected as working fluid in the ORC-section. Sliding vanes machines expander and pump – are considered as rotary equipment. Flat plate heat exchangers complete the base layout, the analysis accounts for. Due to the need for DHW production, a storage unit for hot water is present, upstream the recovery branch: dependently on the ability the fluid at the collector outlet has to meet the ORC requirements for proper operation (about 110°C), the ORC evaporator is fed and the recovery section enabled. Both continuous and unsteady operation underwent an in-depth analysis, as well as the benefits associated with different discharge times for the storage unit. A dedicated control strategy is defined, dependently on whether the electrical output or the thermal one need to be maximized, and accounts for either a flash or a progressive tank discharge. A virtual platform allowed the setting-up of a pilot plant, for direct performance assessment, in presence of different amounts of tank discharges per day and different lower temperatures at the storage tank.
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Carpenter, Chris. « Automated Drilling-Fluids-Measurement Technique Improves Fluid Control, Quality ». Journal of Petroleum Technology 73, no 11 (1 novembre 2021) : 53–54. http://dx.doi.org/10.2118/1121-0053-jpt.
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This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 204041, “Automatic Drilling-Fluids Monitoring,” by Knut Taugbøl, SPE, Equinor, and Bengt Sola and Matthew Forshaw, SPE, Baker Hughes, et al., prepared for the 2021 SPE/IADC International Drilling Conference and Exhibition, originally scheduled to be held in Stavanger, 9–11 March. The paper has not been peer reviewed. The complete paper presents new units for automatic drilling-fluids measurements with emphasis on offshore drilling applications. The surveillance of fluid properties and the use of data in an onshore operations center is discussed. The authors present experiences from use of these data in enabling real-time hydraulic measurements and models for automatic drilling control and explain how these advances can improve safety in drilling operations and drilling efficiency. Introduction An operator has worked with different suppliers for several years to find and develop technology for automatic measurements of drilling-fluid properties. In the described study, methods for measuring parameters such as viscosity, fluid loss control, pH, electrical stability, particle-size distribution, and cuttings morphology and mineralogy were all fitted into a flow loop in an onshore test center. These tests, however, were all performed with prototype equipment. Since then, work has continued to optimize equipment for offshore installations, made for operating in harsh environments and requiring limited maintenance to provide continuous and reliable data quality. The fluid-measuring technique presented in this paper is based on rheology measurement through a pipe rheometer and density measurements through a Coriolis meter. This rheometer measures at ambient temperature. Dual DP is the terminology that refers to pressure measurements between two differential pressure sensors. The dual-DP pipe rheometer is set up with high-accuracy pressure transducers to measure pressure loss inside the straight section of the pipe rheometer. By varying the flow rate through pipes of different dimensions, a rheology profile at varying shear rates can be calculated. Field Implementation Installation of a unit begins with a rig survey conducted in concert with the drilling contractor to find the best location and sampling point. Fluid normally is taken from the charge manifold for the mud pumps, ensuring measurement of the fluid going into the well. The first installation in the North Sea of an automatic fluid-monitoring (AFM) unit was in 2017. This unit is still operational, sending data to an onshore support center. Fig. 1 shows such a unit installed offshore. The AFM unit has only one movable part, the monopump supplying drilling fluid through the unit. Once the dual-DP rheometer was factory-acceptance-tested in the yard, it was sent offshore to be commissioned and verified on a fixed installation in the North Sea. The related data presented in the complete paper were acquired in the field while drilling the 355-m, 8½-in. section with 1.35-SG low-equivalent-circulating-density oil-based drilling fluid, with drilling conducted at approximately 4000 m measured depth. The mud engineer onboard was requested to perform rheology checks on a viscometer at equal ambient temperature to the AFM so that the results could be compared; the AFM also measures rheology at ambient temperature.
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Krishna, C. Vamsi, Namrata Gundiah et Jaywant H. Arakeri. « Separations and secondary structures due to unsteady flow in a curved pipe ». Journal of Fluid Mechanics 815 (14 février 2017) : 26–59. http://dx.doi.org/10.1017/jfm.2017.7.
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Unsteady flows in highly curved geometries are of interest in many engineering applications and also in physiological flows. In this study, we use flow visualization and computational fluid dynamics to study unsteady flows in a highly curved tube ($\unicode[STIX]{x1D6FD}=0.3$) with square cross-section; here, $\unicode[STIX]{x1D6FD}$ is the ratio of the half edge length to the radius of curvature of the tube. To explore the combined effects of curvature and pulsatility, we use a single flow pulse of duration $T$ and peak area averaged axial velocity $U_{p(max)}$, which are independently varied to investigate a range of Dean and Womersley numbers. This range includes cases corresponding to flows in the ascending aorta. We observe radially inward moving secondary flows which have the structure of wall jets on the straight walls; their subsequent collision on the inner wall leads to a re-entrant radially outward moving jet. The wall jet arises due to an imbalance between the centrifugal force and the radial pressure gradient. During the deceleration phase, the low-axial-momentum fluid accumulated in the jet reverses direction and leads to flow separation near the inner wall. We use boundary layer equations to derive scales, which have not been reported earlier, for the secondary flow velocities, the wall shear stress components and the distance ($\hat{P}$) traversed by the secondary flow structures in the transverse plane. We show that $\hat{P}$ predicts the movement of vortical structures until collision. In the limit $\unicode[STIX]{x1D6FD}\rightarrow 0$, the Reynolds number based on this secondary flow velocity scale asymptotes to the secondary streaming Reynolds number proposed by Lyne (J. Fluid Mech., vol. 45 (01), 1971, pp. 13–31) in loosely curved pipes. The magnitude of the secondary flow velocity is high and ${\sim}40\,\%$ of $U_{p(max)}$ for physiological flow conditions. We show that the flow separation on the inner wall has origins in the secondary flow, which was reported in a few earlier studies, and is not due to the axial pressure gradient in the tube as proposed earlier. The wall shear stress components, hypothesized to be important in arterial mechanobiology, may be estimated using our scaling relations for geometries with different curvatures and varying pulsatilities.
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Aravelli, Aparna, Dwayne McDaniel et Clarice Davila. « Assessment of Wave-Guided Ultrasonic Transducer System for Erosion-Corrosion Detection in Nuclear Applications ». International Symposium on Microelectronics 2018, no 1 (1 octobre 2018) : 000694–98. http://dx.doi.org/10.4071/2380-4505-2018.1.000694.
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Abstract Storage tanks and pipelines are used at nuclear waste sites across the Department of Energy (DOE) complex to store and transfer nuclear wastes. One of the significant aspects in such sites is monitoring the structural integrity of the waste transfer pipelines and the storage tanks. Literature indicates that the industry standard method of thickness measurements using ultrasonic sensors is mainly through manual inspections. As such, this procedure is expensive and exhaustive for nuclear applications. Hence, in this research, the authors assess a wave guided ultrasonic sensor system for erosion-corrosion (thickness change) detection in waste transfer pipelines at Hanford nuclear waste site. This ultrasonic transducer (UT) sensor system (from Permasense, a UK based manufacturer [2]) has the advantage of real-time remote monitoring. It is an integrated wireless sensor network system which uses a patented technology for the acoustic wave propagation and has proven applications in the oil and gas industries [3]. This UT sensor system meets the requirement of providing the actual thickness measurement in pipes, is capable for 2 inch pipes and elbows, and is customized for mounting with a mechanical clamping system. The sensors are also capable of operating at high temperatures up to 600°C (1100°F). This is due to their patented waveguide technology that holds the sensor head (containing ultrasonic transducers, electronics, and battery) away from the hot metal surface. The sensor's measurements are transmitted wirelessly back to a gateway (wireless access point) mounted near the main unit. Since there is no cost associated with measurement acquisition or measurement retrieval, the frequency of measurement can be configured to be as frequent as every 15 minutes. Connection of the gateway to the operator's existing information technology infrastructure allows the data to be viewed from personnel desks. Sensor battery life of up to 10 years allows continuous data delivery between turnarounds without access to a sensor's physical location. The sensor model chosen for the present research (testing and validation) is the WT 210 series [2]. It consists of the 304 stainless steel wave guides, sensor head, antenna, battery and a stabilizer. In addition there is a built in thermocouple probe to monitor the pipe surface temperature which also allows the wall thickness measurement to be temperature compensated when required. The sensors communicate using a customized wireless protocol, creating a self-forming and self-managing wireless mesh, which delivers continuous wall thickness measurements of the highest integrity and accuracy directly to the end user. Scope of the present research includes the initial verification and validation of the Permasense Guided Wave sensor system as a potential erosion/corrosion detection system for carbon steel pipelines under static conditions. The real-time erosion/corrosion detection is also investigated by measuring the thinning of the pipe sections by circulating simulants and continuous monitoring. This is achieved by passing abrasive solutions through an in-house designed pipe loop system. The loop has been designed to replicate the sections and carbon steel pipe material similar to the existing system at Hanford site. Varying concentrations of sand and water mixture is used as an eroding agent [5]. The erosion experiments are conducted for several months and the results obtained provide realistic wear rates on 2 inch and 3 inch carbon steel pipes with straight sections and elbows using the Permasense UT sensor system. Thus, the present research delivers solutions for sensor evaluations and conducts bench scale testing followed by data acquisition and analysis for corrosion and erosion assessment. This assessment of the UT sensor system will be useful for monitoring the real-time thinning of the waste transfer pipelines and to deliver more realistic estimates of the remaining useful life of the components and incorporate those estimates into future design/testing plans across the nuclear waste sites.
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Swift, P. D., R. Lawlor, G. B. Smith et A. Gentle. « Rectangular-section mirror light pipes ». Solar Energy Materials and Solar Cells 92, no 8 (août 2008) : 969–75. http://dx.doi.org/10.1016/j.solmat.2008.02.029.
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Khan, M. Kamran, M. Hesham El Naggar et Mohamed Elkasabgy. « Compression testing and analysis of drilled concrete tapered piles in cohesive-frictional soil ». Canadian Geotechnical Journal 45, no 3 (mars 2008) : 377–92. http://dx.doi.org/10.1139/t07-107.
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When pile driving is difficult and (or) economically not viable, cast-in-place piles are indispensable. Tapered piles, which have top cross-sections larger than the bottom cross-sections, have the potential for substantial advantages over conventional straight-sided piles. This paper investigates the construction and performance of innovative drilled concrete tapered piles. A full-scale pile load-testing program was conducted to evaluate the axial compressive capacity of drilled concrete tapered piles in frictional soil. One straight and three tapered augers were designed and manufactured to produce six piles. The piles that were constructed and tested included four tapered and two straight piles. The testing results showed that tapered piles with a taper angle varying between 0.95° and 1.91° had a load carrying capacity up to 50% higher than the straight-sided piles with equal volume. It should be noted, however, that the experimental results are site specific. Moreover, an analytical expression was developed to evaluate the pile taper effect on its shaft capacity in terms of a taper coefficient, Kt. The value of Kt evaluated from the analytical expression compared well with experimentally measured values. Finally, a two dimensional nonlinear finite element analysis was conducted to simulate the load test conditions, and it proved to be successful.
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Kusno. « Pipes Construction Based on the Pipes' ; Centre Curve Shapes ». Journal of Mathematics Research 11, no 4 (28 juillet 2019) : 69. http://dx.doi.org/10.5539/jmr.v11n4p69.
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Parts of pipeline need a long piece, a short segment, and various inflate-deflate models. They require as well the thickness and curvature of the pipes. The objective of this paper is to obtain some formulas for modeling the long pipe, the short tube, and various inflate-deflate pipe patches. Relating to the purposes, we use their cross-section, longitudinal section, and center curves of the pipe parts. The methods are, the using of the polar coordinates and of the real functions, to define the cross and longitudinal section of the pipe patches, respectively. Then, we calculate three orthonormal vectors that are determined by the tangent vectors of the pipe center curves and two unit vectors that are perpendicular to the tangent vectors. After that, we evaluate the formulas to model the long pipes and the short pipes, both inflate-deflate and thickness shapes. The results show that, using its center curves of the pipe, it is handy to design the long and short pipes, multiple thicknesses, various volume fluctuations of the pipes, and useful to model the inflate-deflate pipe parts.
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Nemchaninova, Victoria, et Dmitriy Spitsov. « Dependence of the throughput of drain pipes of different cross-section ». E3S Web of Conferences 244 (2021) : 05012. http://dx.doi.org/10.1051/e3sconf/202124405012.
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Flat drain pipes are a modern drainage solution. The flat profile increases the strength and rigidity of the pipe. The paper considers the experience of using flat pipes for drainage of territories in the whole world. A study of the dependence of the throughput of flat drain pipes on the slope was carried out, and a comparison was made with the throughput of round pipes. With the help of roughness, calculations of the throughput of flat and round pipes were made, and the low throughput of the section of a flat corrugated pipe compared to a round one was proved. A comparison of the efficiency of using pipes of different cross-sections is made using the example of wall drainage. The inexpediency of using flat drain pipes as wall drainage has been substantiated.
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Kusno. « On the modeling of cross-section and longitudinal section of pipes ». Journal of Physics : Conference Series 1321 (octobre 2019) : 022068. http://dx.doi.org/10.1088/1742-6596/1321/2/022068.
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Zhang, Xi, Jun Bao Yang et Min Deng. « Model for Heat Pipe Position Optimization of Transformers Cooled by Heat Pipes ». Advanced Materials Research 347-353 (octobre 2011) : 3765–71. http://dx.doi.org/10.4028/www.scientific.net/amr.347-353.3765.
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In the view of heat pipe position optimization of transformers cooled by heat pipes, using the thermal equilibrium equation and the empirical formula of heat transfer coefficient of the evaporation and condensation section, applying Newton Iteration, computing the optimal condensation section area, the optimal computation of heat pipes’ position is implemented and the model of heat pipe position optimization of transformers cooled by heat pipes is set up.
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Oladunjoye, M. A., K. O. Adejato et A. O. Ogunkoya. « Geophysical investigation of foundation failure at Medina Estate, Lagos, Southwestern Nigeria ». Global Journal of Geological Sciences 18 (25 juin 2020) : 35–47. http://dx.doi.org/10.4314/gjgs.v18i1.4.
Texte intégralRésumé :
Integrated geophysical investigation involving Ground Penetrating Radar (GPR) and Electrical Resistivity methods were carried out at Medina Estate, Lagos southwestern Nigeria to map the subsurface lithology in order to delineate its peat stratigraphy that has been causing foundation failure in the area. Twenty-one traverses (varying from 35-880 m in length) of Ground Penetrating Radar (GPR) survey were conducted along the streets of Medina trending NE-SW and NW-SE directions using the Mala 250 MHZ bi-static shielded antenna. Thirty-six Vertical Electrical Soundings (VES) were carried out using Schlumberger electrode array at some selected points along the established traverses within the area. The GPR data were processed into radar section using Rad Explorer software. The VES data were interpreted quantitatively using the partial curve matching method and 1-D forward modeling with Win Resist Software. Available litho-logs from boreholes drilled within the area were compared with the geophysical results. Results of the GPR survey delineated three geologic layers which include the topsoil with high amplitude, parallel to sub parallel, horizontal reflections, with thickness varying from 1 to 2 m across the entire profiles and composed of lateritic clay; peat layer with low amplitude, parallel sinuous/wavy reflections with depth of occurrence ranging from 2.0 to 8 m and clay with low amplitude, planar, horizontal, sub-parallel reflections underlying the peat layer. Vertical Electrical Sounding results revealed the presence of three geological layers which are the topsoil, peat and clay and sandy clay with layer resistivity values ranging from 20- 225 Ωm, 5 – 90 Ωm and 36 to 366 Ωm and thickness values ranging from 0.5 – 2 m, 4.0-29.0 m and infinity respectively. Borehole information confirms the occurrence of shallow peat with depth ranging from 1.5 to 9 m and clay layer with depth ranging from 9 to 21 m beneath the area. The GPR survey results correlates with the well logs acquired in the study area. Based on the correlation of the geophysical results with the well logs, the GPR gives better information about the peat layer compared to the Electrical ResistivityMethod. The information obtained from this study shows that the soils at shallow depth are organic soils which are difficult foundation materials because they exhibit very high compressibility, as such making shallow foundation impossible except some form of soil improvement is carried out. The alternative approach is the adoption of deep foundations in form of piles.
Keywords: Foundation Failure, Geophysical Investigation, Ground Penetrating Radar, Vertical Electrical Sounding, Peat.
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Malyi, L. P., V. V. Lavreshov, E. N. Kramarenko et D. S. Omelchenko. « A Rectangular Section Pipes Winding Programs Calculation Procedure ». Kosmičeskaâ tehnika. Raketnoe vooruženie 2018, no 1 (14 septembre 2018) : 85–91. http://dx.doi.org/10.33136/stma2018.01.085.
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Barnea, D., N. Ben Yoseph et Y. Taitel. « Flooding in inclined pipes - Effect of entrance section ». Canadian Journal of Chemical Engineering 64, no 2 (avril 1986) : 177–84. http://dx.doi.org/10.1002/cjce.5450640202.
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Xia, Hong Yan, Qing Bian et Di Wu. « Study on Mathematical Model of Dieless Drawing Speed Control for Variable Section Pipes ». Applied Mechanics and Materials 373-375 (août 2013) : 2034–37. http://dx.doi.org/10.4028/www.scientific.net/amm.373-375.2034.
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Dieless drawing, as a flexible metal forming method, could form pipes with arbitrary variable section. In order to control the shape and dimensions accurately, based on the analysis of deformation mechanism of arbitrary variable section pipes via dieless drawing process, the calculation method of dieless drawing speed during pipe forming is proposed theoretically,Furthermore, mathematical model of dieless drawing speed control is established by using piecewise polynomial to approach continuous speed curve. The study provide the basis for the dieless drawing speed microcomputer control system. The results of experimental investigation showed that the mathematical model indicates variation of dieless drawing speed quite well, and it is available to schedule the speeds for arbitrary variable section pipes dieless drawing.
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Wang, F. H., An Yuan Jiao, S. Q. Yang et X. Q. Gao. « Experimental Study and FEM Analysis on Ceramic Composite Coating ». Advanced Materials Research 79-82 (août 2009) : 783–86. http://dx.doi.org/10.4028/www.scientific.net/amr.79-82.783.
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Using gravitational separation Self-propagating High-temperature Synthesis(SHS) process, ceramic composite coating was made in large cross-section rectangular pipes and hemming plate, which can be use directly and also can be cut into the ceramics clad steel plate. The experimental results showed that the surface of ceramics coating, for using section steel as core of large cross-section rectangular pipes or hemming plate combination pipes, is glossy, and its thickness is among 1.5~3.5mm. Metallurgical bonding between steel substrate and ceramics coating can not come into being and the mode of their joint is mainly mechanical bonding. The cooling process of the ceramic-lined square steel tubular was simulated by use of ANSYS. Temperature-time curves of composite rectangular pipes with different thickness and residual stress distribution were calculated, and the reason for creating bonding force. These provided a reference to choose the technologic parameters.
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Santos, Diogo L. F., Larissa S. Marquardt, Paulo H. D. Santos et Thiago Antonini Alves. « Metallic Mesh as Capillary Structure Applied in Heat Pipe Heat Exchanger for Heat Recovery ». Advanced Materials Research 1082 (décembre 2014) : 309–14. http://dx.doi.org/10.4028/www.scientific.net/amr.1082.309.
Texte intégralRésumé :
This work presents a theoretical and experimental analysis of a heat exchanger assisted by five heat pipes made of copper with a metallic mesh 100 of stainless steel which was used as capillary structure. All heat pipes used water as the working fluid and were designed based on the capillary limit model. The heat pipes were developed and tested under heat loads varying from 20 to 50 W before application into the heat exchanger. The theoretical and experimental results were compared and all heat pipes worked satisfactorily. Thereafter, it is presented the development of heat pipe heat exchanger which was tested under heat loads varying from 100 to 250 W. The highest temperature measured on the external surface of the heat pipes was 90 oC and the heat exchanger thermal efficiency varied from 74 to 80%. It is showed that the use of a stainless steel mesh as a porous wick was proved to work successfully in heat pipes.