UOE Pipe Manufacturing Process Simulation: Equipment Designing and Construction

NASA Astrophysics Data System (ADS)

Delistoian, Dmitri; Chirchor, Mihael

2017-12-01

UOE pipe manufacturing process influence directly on pipeline resilience and operation capacity. At present most spreaded pipe manufacturing method is UOE. This method is based on cold forming. After each technological step appears a certain stress and strain level. For pipe stress strain study is designed and constructed special equipment that simulate entire technological process.UOE pipe equipment is dedicated for manufacturing of longitudinally submerged arc welded DN 400 (16 inch) steel pipe.

Friction Stir Welding of Line-Pipe Steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanderson, Samuel; Mahoney, Murray; Feng, Zhili

Friction stir welding (FSW) offers both economic and technical advantages over conventional fusion welding practices for welding line-pipe. For offshore line-pipe construction, the economic savings has been shown to be considerable, approaching a calculated 25%. Offshore pipe is relatively small diameter but heavy wall compared to onshore pipe. One concern is the ability to achieve consistent full weld penetration in an on-site offshore FSW operation, e.g., on a lay-barge. In addition, depending on the size and morphology of the unwelded zone, lack of penetration at the weld root can be difficult if not impossible to detect by conventional NDE methods.more » Thus, an approach to assure consistent full penetration via process control is required for offshore line-pipe construction using FSW. For offshore construction, an internal structural mandrel can be used offering the opportunity to use a sacrificial anvil FSW approach. With this approach, a small volume of sacrificial material can be inserted into the structural anvil. The FSW tool penetrates into the sacrificial anvil, beyond the inner diameter of the pipe wall, thus assuring full penetration. The sacrificial material is subsequently removed from the pipe inner wall. In the work presented herein, FSW studies were completed on both 6 mm and 12 mm wall thickness line-pipe. Lastly, post-FSW evaluations including radiography, root-bend tests, and metallography demonstrated the merits of the sacrificial anvil approach to achieve consistent full penetration.« less

Structural and mechanical defects of materials of offshore and onshore main gas pipelines after long-term operation

NASA Astrophysics Data System (ADS)

Maruschak, Pavlo; Panin, Sergey; Danyliuk, Iryna; Poberezhnyi, Lyubomyr; Pyrig, Taras; Bishchak, Roman; Vlasov, Ilya

2015-10-01

The study has established the main regularities of a fatigue failure of offshore gas steel pipes installed using S-lay and J-lay methods.We have numerically analyzed the influence of preliminary deformation on the fatigue life of 09Mn2Si steel at different amplitudes of cyclic loading. The results have revealed the regularities of formation and development of a fatigue crack in 17Mn1Si steel after 40 years of underground operation. The quantitative analysis describes the regularities of occurrence and growth of fatigue cracks in the presence of a stress concentration.

Identification of sewer pipes to be cleaned for reduction of CSO pollutant load.

PubMed

Nagaiwa, Akihiro; Settsu, Katsushi; Nakajima, Fumiyuki; Furumai, Hiroaki

2007-01-01

To reduce the CSO (Combined Sewer Overflow) pollutant discharge, one of the effective options is cleaning of sewer pipes before rainfall events. To maximize the efficiency, identification of pipes to be cleaned is necessary. In this study, we discussed the location of pipe deposit in dry weather in a combined sewer system using a distributed model and investigated the effect of pipe cleaning to reduce the pollutant load from the CSO. First we simulated the dry weather flow in a combined sewer system. The pipe deposit distribution in the network was estimated after 3 days of dry weather period. Several specific pipes with structural defect and upper end pipes tend to have an accumulation of deposit. Wet weather simulations were conducted with and without pipe cleaning in rainfall events with different patterns. The SS loads in CSO with and without the pipe cleaning were compared. The difference in the estimated loads was interpreted as the contribution of wash-off in the cleaned pipe. The effect of pipe cleaning on reduction of the CSO pollutant load was quantitatively evaluated (e.g. the cleaning of one specific pipe could reduce 22% of total CSO load). The CSO simulations containing pipe cleaning options revealed that identification of pipes with accumulated deposit using the distributed model is very useful and informative to evaluate the applicability of pipe cleaning option for CSO pollutant reduction.

A design of endoscopic imaging system for hyper long pipeline based on wheeled pipe robot

NASA Astrophysics Data System (ADS)

Zheng, Dongtian; Tan, Haishu; Zhou, Fuqiang

2017-03-01

An endoscopic imaging system of hyper long pipeline is designed to acquire the inner surface image in advance for the hyper long pipeline detects measurement. The system consists of structured light sensors, pipe robots and control system. The pipe robot is in the form of wheel structure, with the sensor which is at the front of the vehicle body. The control system is at the tail of the vehicle body in the form of upper and lower computer. The sensor can be translated and scanned in three steps: walking, lifting and scanning, then the inner surface image can be acquired at a plurality of positions and different angles. The results of imaging experiments show that the system's transmission distance is longer, the acquisition angle is more diverse and the result is more comprehensive than the traditional imaging system, which lays an important foundation for later inner surface vision measurement.

Chemical laser exhaust pipe design research

NASA Astrophysics Data System (ADS)

Sun, Yunqiang; Huang, Zhilong; Chen, Zhiqiang; Ren, Zebin; Guo, Longde

2016-10-01

In order to weaken the chemical laser exhaust gas influence of the optical transmission, a vent pipe is advised to emissions gas to the outside of the optical transmission area. Based on a variety of exhaust pipe design, a flow field characteristic of the pipe is carried out by numerical simulation and analysis in detail. The research results show that for uniform deflating exhaust pipe, although the pipeline structure is cyclical and convenient for engineering implementation, but there is a phenomenon of air reflows at the pipeline entrance slit which can be deduced from the numerical simulation results. So, this type of pipeline structure does not guarantee seal. For the design scheme of putting the pipeline contract part at the end of the exhaust pipe, or using the method of local area or tail contraction, numerical simulation results show that backflow phenomenon still exists at the pipeline entrance slit. Preliminary analysis indicates that the contraction of pipe would result in higher static pressure near the wall for the low speed flow field, so as to produce counter pressure gradient at the entrance slit. In order to eliminate backflow phenomenon at the pipe entrance slit, concerned with the pipeline type of radial size increase gradually along the flow, flow field property in the pipe is analyzed in detail by numerical simulation methods. Numerical simulation results indicate that there is not reflow phenomenon at entrance slit of the dilated duct. However the cold air inhaled in the slit which makes the temperature of the channel wall is lower than the center temperature. Therefore, this kind of pipeline structure can not only prevent the leak of the gas, but also reduce the wall temperature. In addition, compared with the straight pipe connection way, dilated pipe structure also has periodic structure, which can facilitate system integration installation.

Refined pipe theory for mechanistic modeling of wood development.

PubMed

Deckmyn, Gaby; Evans, Sam P; Randle, Tim J

2006-06-01

We present a mechanistic model of wood tissue development in response to changes in competition, management and climate. The model is based on a refinement of the pipe theory, where the constant ratio between sapwood and leaf area (pipe theory) is replaced by a ratio between pipe conductivity and leaf area. Simulated pipe conductivity changes with age, stand density and climate in response to changes in allocation or pipe radius, or both. The central equation of the model, which calculates the ratio of carbon (C) allocated to leaves and pipes, can be parameterized to describe the contrasting stem conductivity behavior of different tree species: from constant stem conductivity (functional homeostasis hypothesis) to height-related reduction in stem conductivity with age (hydraulic limitation hypothesis). The model simulates the daily growth of pipes (vessels or tracheids), fibers and parenchyma as well as vessel size and simulates the wood density profile and the earlywood to latewood ratio from these data. Initial runs indicate the model yields realistic seasonal changes in pipe radius (decreasing pipe radius from spring to autumn) and wood density, as well as realistic differences associated with the competitive status of trees (denser wood in suppressed trees).

Simulation of the early startup period of high-temperature heat pipes from the frozen state by a rarefied vapor self-diffusion model

NASA Technical Reports Server (NTRS)

Cao, Y.; Faghri, A.

1993-01-01

The heat pipe startup process is described physically and is divided into five periods for convenience of analysis. The literature survey revealed that none of the previous attempts to simulate the heat pipe startup process numerically were successful, since the rarefied vapor flow in the heat pipe was not considered. Therefore, a rarefied vapor self-diffusion model is proposed, and the early startup periods, in which the rarefied vapor flow is dominant within the heat pipe, are first simulated numerically. The numerical results show that large vapor density gradients existed along the heat pipe length, and the vapor flow reaches supersonic velocities when the density is extremely low. The numerical results are compared with the experimental data of the early startup period with good agreement.

Energy saving potential of a two-pipe system for simultaneous heating and cooling of office buildings

DOE PAGES

Maccarini, Alessandro; Wetter, Michael; Afshari, Alireza; ...

2016-10-31

This paper analyzes the performance of a novel two-pipe system that operates one water loop to simultaneously provide space heating and cooling with a water supply temperature of around 22 °C. To analyze the energy performance of the system, a simulation-based research was conducted. The two-pipe system was modelled using the equation-based Modelica modeling language in Dymola. A typical office building model was considered as the case study. Simulations were run for two construction sets of the building envelope and two conditions related to inter-zone air flows. To calculate energy savings, a conventional four-pipe system was modelled and used formore » comparison. The conventional system presented two separated water loops for heating and cooling with supply temperatures of 45 °C and 14 °C, respectively. Simulation results showed that the two-pipe system was able to use less energy than the four-pipe system thanks to three effects: useful heat transfer from warm to cold zones, higher free cooling potential and higher efficiency of the heat pump. In particular, the two-pipe system used approximately between 12% and 18% less total annual primary energy than the four-pipe system, depending on the simulation case considered.« less

Energy saving potential of a two-pipe system for simultaneous heating and cooling of office buildings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maccarini, Alessandro; Wetter, Michael; Afshari, Alireza

This paper analyzes the performance of a novel two-pipe system that operates one water loop to simultaneously provide space heating and cooling with a water supply temperature of around 22 °C. To analyze the energy performance of the system, a simulation-based research was conducted. The two-pipe system was modelled using the equation-based Modelica modeling language in Dymola. A typical office building model was considered as the case study. Simulations were run for two construction sets of the building envelope and two conditions related to inter-zone air flows. To calculate energy savings, a conventional four-pipe system was modelled and used formore » comparison. The conventional system presented two separated water loops for heating and cooling with supply temperatures of 45 °C and 14 °C, respectively. Simulation results showed that the two-pipe system was able to use less energy than the four-pipe system thanks to three effects: useful heat transfer from warm to cold zones, higher free cooling potential and higher efficiency of the heat pump. In particular, the two-pipe system used approximately between 12% and 18% less total annual primary energy than the four-pipe system, depending on the simulation case considered.« less

16. THE INSTALLATION OF CONVEYORS AND OVERHEAD RAILS ELIMINATED THE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

16. THE INSTALLATION OF CONVEYORS AND OVERHEAD RAILS ELIMINATED THE NEED TO LAY MOLDS OUT ON FLOORS AND HAND-POUR THEM. INSTEAD, WORKERS PULLED LARGE LADLES ALONG OVERHEAD RAILS AND FILLED CONVEYOR-DRIVEN MOLDS WHILE THEY STOOD ON A MOVING PLATFORM THAT TRAVELED AT THE SAME SPEED AS THE MOLD CONVEYOR, CA. 1950. - Stockham Pipe & Fittings Company, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

Simulation of a manual electric-arc welding in a working gas pipeline. 2. Numerical investigation of the temperature-stress distribution in the wall of a gas pipe

NASA Astrophysics Data System (ADS)

Baikov, V. I.; Gishkelyuk, I. A.; Rus', A. M.; Sidorovich, T. V.; Tonkonogov, B. A.

2010-11-01

A numerical simulation of the action of the current experienced by an electric arc and the rate of gas flow in a pipe of a cross-country gas pipeline on the depth of penetration of the electric arc into the wall of this pipe and on the current and residual stresses arising in the pipe material in the process of electric-arc welding of nonthrough cavity-like defects in it has been carried out for gas pipes with walls of different thickness.

Reeled pipelay cost reduction using workboat-based installation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoffman, J.G.; El Laithy, W.F.; Rothberg, R.H.

1995-11-01

Coiled ``tubing`` is a rapidly growing pipeline technology. because this technology is relatively new, cost can vary significantly depending on deployment strategies and installation techniques. Up until recently coiled pipe was used primarily by service companies for coiled tubing workovers. As the technology expanded the industry began using coiled tubing for other applications such as drilling, coring, logging, well cleanout operations and artificial lift. With the recent advent of larger sizes, three and one half inches, it was now possible to consider using coiled tubing as pipelines. The coiled pipe was proving to be a low cost, time saving, economicmore » alternative to conventional welded pipe for flowlines. Coiled pipe applications have been used in 4 to 100 feet of water in the Gulf of Mexico area and the installation techniques have varied significantly. Considerable engineering work has been done in preparation for GUPCO`s first dynamic lay installation for a subsea well tie-in on Ramadan 22. Subsequently GUPCO installed the worlds longest known coiled pipeline on SB 367. This paper will cover the significant findings of that engineering work and present actual field case histories on Egypt`s first two coiled pipeline projects.« less

Nest construction by a ground-nesting bird represents a potential trade-off between egg crypticity and thermoregulation.

PubMed

Mayer, Paul M; Smith, Levica M; Ford, Robert G; Watterson, Dustin C; McCutchen, Marshall D; Ryan, Mark R

2009-04-01

Predation selects against conspicuous colors in bird eggs and nests, while thermoregulatory constraints select for nest-building behavior that regulates incubation temperatures. We present results that suggest a trade-off between nest crypticity and thermoregulation of eggs based on selection of nest materials by piping plovers (Charadrius melodus), a ground-nesting bird that constructs simple, pebble-lined nests highly vulnerable to predators and exposed to temperature extremes. Piping plovers selected pebbles that were whiter and appeared closer in color to eggs than randomly available pebbles, suggesting a crypsis function. However, nests that were more contrasting in color to surrounding substrates were at greater risk of predation, suggesting an alternate strategy driving selection of white rocks. Near-infrared reflectance of nest pebbles was higher than randomly available pebbles, indicating a direct physical mechanism for heat control through pebble selection. Artificial nests constructed of randomly available pebbles heated more quickly and conferred heat to model eggs, causing eggs to heat more rapidly than in nests constructed from piping plover nest pebbles. Thermal models and field data indicated that temperatures inside nests may remain up to 2-6 degrees C cooler than surrounding substrates. Thermal models indicated that nests heat especially rapidly if not incubated, suggesting that nest construction behavior may serve to keep eggs cooler during the unattended laying period. Thus, pebble selection suggests a potential trade-off between maximizing heat reflectance to improve egg microclimate and minimizing conspicuous contrast of nests with the surrounding substrate to conceal eggs from predators. Nest construction behavior that employs light-colored, thermally reflective materials may represent an evolutionary response by birds and other egg-laying organisms to egg predation and heat stress.

Asymptotic scalings of developing curved pipe flow

NASA Astrophysics Data System (ADS)

Ault, Jesse; Chen, Kevin; Stone, Howard

2015-11-01

Asymptotic velocity and pressure scalings are identified for the developing curved pipe flow problem in the limit of small pipe curvature and high Reynolds numbers. The continuity and Navier-Stokes equations in toroidal coordinates are linearized about Dean's analytical curved pipe flow solution (Dean 1927). Applying appropriate scaling arguments to the perturbation pressure and velocity components and taking the limits of small curvature and large Reynolds number yields a set of governing equations and boundary conditions for the perturbations, independent of any Reynolds number and pipe curvature dependence. Direct numerical simulations are used to confirm these scaling arguments. Fully developed straight pipe flow is simulated entering a curved pipe section for a range of Reynolds numbers and pipe-to-curvature radius ratios. The maximum values of the axial and secondary velocity perturbation components along with the maximum value of the pressure perturbation are plotted along the curved pipe section. The results collapse when the scaling arguments are applied. The numerically solved decay of the velocity perturbation is also used to determine the entrance/development lengths for the curved pipe flows, which are shown to scale linearly with the Reynolds number.

Passive advection-dispersion in networks of pipes: Effect of connectivity and relationship to permeability

NASA Astrophysics Data System (ADS)

Bernabé, Y.; Wang, Y.; Qi, T.; Li, M.

2016-02-01

The main purpose of this work is to investigate the relationship between passive advection-dispersion and permeability in porous materials presumed to be statistically homogeneous at scales larger than the pore scale but smaller than the reservoir scale. We simulated fluid flow through pipe network realizations with different pipe radius distributions and different levels of connectivity. The flow simulations used periodic boundary conditions, allowing monitoring of the advective motion of solute particles in a large periodic array of identical network realizations. In order to simulate dispersion, we assumed that the solute particles obeyed Taylor dispersion in individual pipes. When a particle entered a pipe, a residence time consistent with local Taylor dispersion was randomly assigned to it. When exiting the pipe, the particle randomly proceeded into one of the pipes connected to the original one according to probabilities proportional to the outgoing volumetric flow in each pipe. For each simulation we tracked the motion of at least 6000 solute particles. The mean fluid velocity was 10-3 ms-1, and the distance traveled was on the order of 10 m. Macroscopic dispersion was quantified using the method of moments. Despite differences arising from using different types of lattices (simple cubic, body-centered cubic, and face-centered cubic), a number of general observations were made. Longitudinal dispersion was at least 1 order of magnitude greater than transverse dispersion, and both strongly increased with decreasing pore connectivity and/or pore size variability. In conditions of variable hydraulic radius and fixed pore connectivity and pore size variability, the simulated dispersivities increased as power laws of the hydraulic radius and, consequently, of permeability, in agreement with previously published experimental results. Based on these observations, we were able to resolve some of the complexity of the relationship between dispersivity and permeability.

Assessment of water pipes durability under pressure surge

NASA Astrophysics Data System (ADS)

Pham Ha, Hai; Minh, Lanh Pham Thi; Tang Van, Lam; Bulgakov, Boris; Bazhenova, Soafia

2017-10-01

Surge phenomenon occurs on the pipeline by the closing valve or pump suddenly lost power. Due to the complexity of the water hammer simulation, previous researches have only considered water hammer on the single pipe or calculation of some positions on water pipe network, it have not been analysis for all of pipe on the water distribution systems. Simulation of water hammer due to closing valve on water distribution system and the influence level of pressure surge is evaluated at the defects on pipe. Water hammer on water supply pipe network are simulated by Water HAMMER software academic version and the capacity of defects are calculated by SINTAP. SINTAP developed from Brite-Euram projects in Brussels-Belgium with the aim to develop a process for assessing the integrity of the structure for the European industry. Based on the principle of mechanical fault, indicating the size of defects in materials affect the load capacity of the product in the course of work, the process has proposed setting up the diagram to fatigue assessment defect (FAD). The methods are applied for water pipe networks of Lien Chieu district, Da Nang city, Viet Nam, the results show the affected area of wave pressure by closing the valve and thereby assess the greatest pressure surge effect to corroded pipe. The SINTAP standard and finite element mesh analysis at the defect during the occurrence of pressure surge which will accurately assess the bearing capacity of the old pipes. This is one of the bases to predict the leakage locations on the water distribution systems. Amount of water hammer when identified on the water supply networks are decreasing due to local losses at the nodes as well as the friction with pipe wall, so this paper adequately simulate water hammer phenomena applying for actual water distribution systems. The research verified that pipe wall with defect is damaged under the pressure surge value.

Water-hammer pressure waves interaction at cross-section changes in series in viscoelastic pipes

NASA Astrophysics Data System (ADS)

Meniconi, S.; Brunone, B.; Ferrante, M.

2012-08-01

In view of scarcity of both experimental data and numerical models concerning transient behavior of cross-section area changes in pressurized liquid flow, the paper presents laboratory data and numerical simulation of the interaction of a surge wave with a partial blockage by a valve, a single pipe contraction or expansion and a series of pipe contraction/expansion in close proximity.With regard to a single change of cross-section area, laboratory data point out the completely different behavior with respect to one of the partially closed in-line valves with the same area ratio. In fact, for the former the pressure wave interaction is not regulated by the steady-state local head loss. With regard to partial blockages, transient tests have shown that the smaller the length, the more intense the overlapping of pressure waves due to the expansion and contraction in series.Numerically, the need for taking into account both the viscoelasticity and unsteady friction is demonstrated, since the classical water-hammer theory does not simulate the relevant damping of pressure peaks and gives rise to a time shifting between numerical and laboratory data. The transient behavior of a single local head loss has been checked by considering tests carried out in a system with a partially closed in-line valve. As a result, the reliability of the quasi steady-state approach for local head loss simulation has been demonstrated in viscoelastic pipes. The model parameters obtained on the basis of transients carried out in single pipe systems have then been used to simulate transients in the more complex pipe systems. These numerical experiments show the great importance of the length of the small-bore pipe with respect to one of the large-bore pipes. Precisely, until a gradually flow establishes in the small-bore pipe, the smaller such a length, the better the quality of the numerical simulation.

Energy transfer mechanism and probability analysis of submarine pipe laterally impacted by dropped objects

NASA Astrophysics Data System (ADS)

Liang, Jing; Yu, Jian-xing; Yu, Yang; Lam, W.; Zhao, Yi-yu; Duan, Jing-hui

2016-06-01

Energy transfer ratio is the basic-factor affecting the level of pipe damage during the impact between dropped object and submarine pipe. For the purpose of studying energy transfer and damage mechanism of submarine pipe impacted by dropped objects, series of experiments are designed and carried out. The effective yield strength is deduced to make the quasi-static analysis more reliable, and the normal distribution of energy transfer ratio caused by lateral impact on pipes is presented by statistic analysis of experimental results based on the effective yield strength, which provides experimental and theoretical basis for the risk analysis of submarine pipe system impacted by dropped objects. Failure strains of pipe material are confirmed by comparing experimental results with finite element simulation. In addition, impact contact area and impact time are proved to be the major influence factors of energy transfer by sensitivity analysis of the finite element simulation.

Plug Repairs of Marine Glass Fiber / Vinyl Ester Laminates Subjected to Uniaxial Tension

DTIC Science & Technology

2009-06-01

Material characteristics of glass fiber / vinyl ester composites used in naval surface ships 1.1.1.2 Construction of surface ship hulls with FRP...Piping - Ventilation ducts - Deck gratings 1.1.1.1 Material characteristics of glass fiber / vinyl ester composites used in naval surface ships The...that polysester-based composites do [15, 24]. Typical processing methods for vinyl ester composites are hand lay-up, Resin Transfer Molding (RTM

A Capsule-Type Electromagnetic Acoustic Transducer for Fast Screening of External Corrosion in Nonmagnetic Pipes.

PubMed

Li, Yong; Cai, Rui; Yan, Bei; Zainal Abidin, Ilham Mukriz; Jing, Haoqing; Wang, Yi

2018-05-28

For fuel transmission and structural strengthening, small-diameter pipes of nonmagnetic materials are extensively adopted in engineering fields including aerospace, energy, transportation, etc. However, the hostile and corrosive environment leaves them vulnerable to external corrosion which poses a severe threat to structural integrity of pipes. Therefore, it is imperative to nondestructively detect and evaluate the external corrosion in nonmagnetic pipes. In light of this, a capsule-type Electromagnetic Acoustic Transducer (EMAT) for in-situ nondestructive evaluation of nonmagnetic pipes and fast screening of external corrosion is proposed in this paper. A 3D hybrid model for efficient prediction of responses from the proposed transducer to external corrosion is established. Closed-form expressions of field quantities of electromagnetics and EMAT signals are formulated. Simulations based on the hybrid model indicate feasibility of the proposed transducer in detection and evaluation of external corrosion in nonmagnetic pipes. In parallel, experiments with the fabricated transducer have been carried out. Experimental results are supportive of the conclusion drawn from simulations. The investigation via simulations and experiments implies that the proposed capsule-type EMAT is capable of fast screening of external corrosion, which is beneficial to the in-situ nondestructive evaluation of small-diameter nonmagnetic pipes.

Numerical simulation of X90 UOE pipe forming process

NASA Astrophysics Data System (ADS)

Zou, Tianxia; Ren, Qiang; Peng, Yinghong; Li, Dayong; Tang, Ding; Han, Jianzeng; Li, Xinwen; Wang, Xiaoxiu

2013-12-01

The UOE process is an important technique to manufacture large-diameter welding pipes which are increasingly applied in oil pipelines and offshore platforms. The forming process of UOE mainly consists of five successive operations: crimping, U-forming, O-forming, welding and mechanical expansion, through which a blank is formed into a pipe in a UOE pipe mill. The blank with an appropriate edge bevel is bent into a cylindrical shape by crimping (C-forming), U-forming and O-forming successively. After the O-forming, there is an open-seam between two ends of the plate. Then, the blank is welded by automatic four-electrode submerged arc welding technique. Subsequently, the welded pipe is expanded with a mechanical expander to get a high precision circular shape. The multiple operations in the UOE mill make it difficult to control the quality of the formed pipe. Therefore, process design mainly relies on experience in practical production. In this study, the UOE forming of an API X90 pipe is studied by using finite element simulation. The mechanical properties tests are performed on the API X90 pipeline steel blank. A two-dimensional finite element model under the hypothesis of plane strain condition is developed to simulate the UOE process according to data coming from the workshop. A kinematic hardening model is used in the simulation to take the Bauschinger effect into account. The deformation characteristics of the blank during the forming processes are analyzed. The simulation results show a significant coherence in the geometric configurations comparing with the practical manufacturing.

Localised surface plasmon-like resonance generated by microwave electromagnetic waves in pipe defects

NASA Astrophysics Data System (ADS)

Alobaidi, Wissam M.; Nima, Zeid A.; Sandgren, Eric

2018-01-01

Localised surface plasmon (LSP)-like resonance phenomena were simulated in COMSOL Multiphysics™, and the electric field enhancement was evaluated in eight pipe defects using the microwave band from 1.80 to 3.00 GHz and analysed by finite element analysis (FEA). The simulation was carried out, in each defect case, on a pipe that has 762 mm length and 152.4 mm inner diameter, and 12.7 mm pipe wall thickness. Defects were positioned in the middle of the pipe and were named as follows; SD: Square Defect, FCD: fillet corner defect, FD: fillet defect, HCD: half circle defect, TCD: triangle corner defect, TD: triangle defect, ZD: zigzag defect, GD: gear defect. The LSP electric field, and scattering parametric (S21, and S11) waves were evaluated in all cases and found to be strongly dependent on the size and the shape of the defect rather than the pipe and or the medium materials.

EPANET 2 USERS MANUAL

EPA Science Inventory

EPANET is a computer program that performs extended period simulation of hydraulic and water quality behavior within pressurized pipe networks. A network consists of pipes, nodes (pipe junctions), pumps, valves and storage tanks or reservoirs. EPANET tracks the flow of water in e...

EPANET VERSION 2.0

EPA Science Inventory

EPANET is a Windows program that performs extended period simulation of hydraulic and water-quality behavior within pressurized pipe networks. A network can consist of pipes, nodes (pipe junctions), pumps, valves and storage tanks or reservoirs. EPANET tracks the flow of water in...

NASA National Combustion Code Simulations

NASA Technical Reports Server (NTRS)

Iannetti, Anthony; Davoudzadeh, Farhad

2001-01-01

A systematic effort is in progress to further validate the National Combustion Code (NCC) that has been developed at NASA Glenn Research Center (GRC) for comprehensive modeling and simulation of aerospace combustion systems. The validation efforts include numerical simulation of the gas-phase combustor experiments conducted at the Center for Turbulence Research (CTR), Stanford University, followed by comparison and evaluation of the computed results with the experimental data. Presently, at GRC, a numerical model of the experimental gaseous combustor is built to simulate the experimental model. The constructed numerical geometry includes the flow development sections for air annulus and fuel pipe, 24 channel air and fuel swirlers, hub, combustor, and tail pipe. Furthermore, a three-dimensional multi-block, multi-grid grid (1.6 million grid points, 3-levels of multi-grid) is generated. Computational simulation of the gaseous combustor flow field operating on methane fuel has started. The computational domain includes the whole flow regime starting from the fuel pipe and the air annulus, through the 12 air and 12 fuel channels, in the combustion region and through the tail pipe.

Simulation and optimization of a pulsating heat pipe using artificial neural network and genetic algorithm

NASA Astrophysics Data System (ADS)

Jokar, Ali; Godarzi, Ali Abbasi; Saber, Mohammad; Shafii, Mohammad Behshad

2016-11-01

In this paper, a novel approach has been presented to simulate and optimize the pulsating heat pipes (PHPs). The used pulsating heat pipe setup was designed and constructed for this study. Due to the lack of a general mathematical model for exact analysis of the PHPs, a method has been applied for simulation and optimization using the natural algorithms. In this way, the simulator consists of a kind of multilayer perceptron neural network, which is trained by experimental results obtained from our PHP setup. The results show that the complex behavior of PHPs can be successfully described by the non-linear structure of this simulator. The input variables of the neural network are input heat flux to evaporator (q″), filling ratio (FR) and inclined angle (IA) and its output is thermal resistance of PHP. Finally, based upon the simulation results and considering the heat pipe's operating constraints, the optimum operating point of the system is obtained by using genetic algorithm (GA). The experimental results show that the optimum FR (38.25 %), input heat flux to evaporator (39.93 W) and IA (55°) that obtained from GA are acceptable.

Transition to Turbulence in curved pipe

NASA Astrophysics Data System (ADS)

Hashemi, Amirreza; Loth, Francis

2014-11-01

Studies have shown that transitional turbulence in a curved pipe is delayed significantly compared with straight pipes. These analytical, numerical and experimental studies employed a helical geometry that is infinitely long such that the effect of the inlet and outlet can be neglected. The present study examined transition to turbulence in a finite curved pipe with a straight inlet/outlet and a 180 degrees curved pipe with a constant radius of curvature and diameter (D). We have employed the large scale direct numerical simulation (DNS) by using the spectral element method, nek5000, to simulate the flow field within curved pipe geometry with different curvature radii and Reynolds numbers to determine the point of the transition to turbulence. Long extensions for the inlet (5D) and outlet (20D) were used to diminish the effect of the boundary conditions. Our numerical results for radius of curvatures of 1.5D and 5D show transition turbulence is near Re = 3000. This is delayed compared with a straight pipe (Re = 2200) but still less that observed for helical geometries (Reynolds number less than 5000). Our research aims to describe the critical Reynolds number for transition to turbulence for a finite curved pipe at various curvature radii.

Mitigating Climate Change with Ocean Pipes: Influencing Land Temperature and Hydrology and Termination Overshoot Risk

NASA Astrophysics Data System (ADS)

Kwiatkowski, L.; Caldeira, K.; Ricke, K.

2014-12-01

With increasing risk of dangerous climate change geoengineering solutions to Earth's climate problems have attracted much attention. One proposed geoengineering approach considers the use of ocean pipes as a means to increase ocean carbon uptake and the storage of thermal energy in the deep ocean. We use a latest generation Earth System Model (ESM) to perform simulations of idealised extreme implementations of ocean pipes. In our simulations, downward transport of thermal energy by ocean pipes strongly cools the near surface atmosphere - by up to 11°C on a global mean. The ocean pipes cause net thermal energy to be transported from the terrestrial environment to the deep ocean while increasing the global net transport of water to land. By cooling the ocean surface more than the land, ocean pipes tend to promote a monsoonal-type circulation, resulting in increased water vapour transport to land. Throughout their implementation, ocean pipes prevent energy from escaping to space, increasing the amount of energy stored in Earth's climate system despite reductions in surface temperature. As a consequence, our results indicate that an abrupt termination of ocean pipes could cause dramatic increases in surface temperatures beyond that which would have been obtained had ocean pipes not been implemented.

The stationary flow in a heterogeneous compliant vessel network

NASA Astrophysics Data System (ADS)

Filoche, Marcel; Florens, Magali

2011-09-01

We introduce a mathematical model of the hydrodynamic transport into systems consisting in a network of connected flexible pipes. In each pipe of the network, the flow is assumed to be steady and one-dimensional. The fluid-structure interaction is described through tube laws which relate the pipe diameter to the pressure difference across the pipe wall. We show that the resulting one-dimensional differential equation describing the flow in the pipe can be exactly integrated if one is able to estimate averages of the Reynolds number along the pipe. The differential equation is then transformed into a non linear scalar equation relating pressures at both ends of the pipe and the flow rate in the pipe. These equations are coupled throughout the network with mass conservation equations for the flow and zero pressure losses at the branching points of the network. This allows us to derive a general model for the computation of the flow into very large inhomogeneous networks consisting of several thousands of flexible pipes. This model is then applied to perform numerical simulations of the human lung airway system at exhalation. The topology of the system and the tube laws are taken from morphometric and physiological data in the literature. We find good qualitative and quantitative agreement between the simulation results and flow-volume loops measured in real patients. In particular, expiratory flow limitation which is an essential characteristic of forced expiration is found to be well reproduced by our simulations. Finally, a mathematical model of a pathology (Chronic Obstructive Pulmonary Disease) is introduced which allows us to quantitatively assess the influence of a moderate or severe alteration of the airway compliances.

Cold Start of a Radiator Equipped with Titanium-Water Heat Pipes

NASA Technical Reports Server (NTRS)

Jaworske, Donald A.; Sanzi, James L.; Siamidis, John

2008-01-01

Radiator panels utilizing titanium-water heat pipes are being considered for lunar applications. A traditional sandwich structure is envisioned where heat pipes are embedded between two high thermal conductivity face sheets. The heat pipe evaporators are to be thermally connected to the heat source through one or more manifolds containing coolant. Initial radiator operation on the lunar surface would likely follow a cold soak where the water in the heat pipes is purposely frozen. To achieve heat pipe operation, it will be necessary to thaw the heat pipes. One option is to allow the sunlight impinging on the surface at sunrise to achieve this goal. Testing was conducted in a thermal vacuum chamber to simulate the lunar sunrise and additional modeling was conducted to identify steady-state and transient response. It was found that sunlight impinging on the radiator surface at sunrise was insufficient to solely achieve the goal of thawing the water in the heat pipes. However, starting from a frozen condition was accomplished successfully by applying power to the evaporators. Start up in this fashion was demonstrated without evaporator dryout. Concern is raised over thawing thermosyphons, vertical heat pipes operating in a gravity field, with no wick in the condenser section. This paper presents the results of the simulated cold start study and identifies future work to support radiator panels equipped with titanium-water heat pipes.

Transient Simulation of Accumulating Particle Deposition in Pipe Flow

NASA Astrophysics Data System (ADS)

Hewett, James; Sellier, Mathieu

2015-11-01

Colloidal particles that deposit in pipe systems can lead to fouling which is an expensive problem in both the geothermal and oil & gas industries. We investigate the gradual accumulation of deposited colloids in pipe flow using numerical simulations. An Euler-Lagrangian approach is employed for modelling the fluid and particle phases. Particle transport to the pipe wall is modelled with Brownian motion and turbulent diffusion. A two-way coupling exists between the fouled material and the pipe flow; the local mass flux of depositing particles is affected by the surrounding fluid in the near-wall region. This coupling is modelled by changing the cells from fluid to solid as the deposited particles exceed each local cell volume. A similar method has been used to model fouling in engine exhaust systems (Paz et al., Heat Transfer Eng., 34(8-9):674-682, 2013). We compare our deposition velocities and deposition profiles with an experiment on silica scaling in turbulent pipe flow (Kokhanenko et al., 19th AFMC, 2014).

Experimental simulation of latent heat thermal energy storage and heat pipe thermal transport for dish concentrator solar receiver

NASA Technical Reports Server (NTRS)

Narayanan, R.; Zimmerman, W. F.; Poon, P. T. Y.

1981-01-01

Test results on a modular simulation of the thermal transport and heat storage characteristics of a heat pipe solar receiver (HPSR) with thermal energy storage (TES) are presented. The HPSR features a 15-25 kWe Stirling engine power conversion system at the focal point of a parabolic dish concentrator operating at 827 C. The system collects and retrieves solar heat with sodium pipes and stores the heat in NaF-MgF2 latent heat storage material. The trials were run with a single full scale heat pipe, three full scale TES containers, and an air-cooled heat extraction coil to replace the Stirling engine heat exchanger. Charging and discharging, constant temperature operation, mixed mode operation, thermal inertial, etc. were studied. The heat pipe performance was verified, as were the thermal energy storage and discharge rates and isothermal discharges.

Welding Penetration Control of Fixed Pipe in TIG Welding Using Fuzzy Inference System

NASA Astrophysics Data System (ADS)

Baskoro, Ario Sunar; Kabutomori, Masashi; Suga, Yasuo

This paper presents a study on welding penetration control of fixed pipe in Tungsten Inert Gas (TIG) welding using fuzzy inference system. The welding penetration control is essential to the production quality welds with a specified geometry. For pipe welding using constant arc current and welding speed, the bead width becomes wider as the circumferential welding of small diameter pipes progresses. Having welded pipe in fixed position, obviously, the excessive arc current yields burn through of metals; in contrary, insufficient arc current produces imperfect welding. In order to avoid these errors and to obtain the uniform weld bead over the entire circumference of the pipe, the welding conditions should be controlled as the welding proceeds. This research studies the intelligent welding process of aluminum alloy pipe 6063S-T5 in fixed position using the AC welding machine. The monitoring system used a charge-coupled device (CCD) camera to monitor backside image of molten pool. The captured image was processed to recognize the edge of molten pool by image processing algorithm. Simulation of welding control using fuzzy inference system was constructed to simulate the welding control process. The simulation result shows that fuzzy controller was suitable for controlling the welding speed and appropriate to be implemented into the welding system. A series of experiments was conducted to evaluate the performance of the fuzzy controller. The experimental results show the effectiveness of the control system that is confirmed by sound welds.

The effect of advanced treatment on chlorine decay in metallic pipes

EPA Science Inventory

Experiments were run to measure what effect advanced treatment might have on the kinetics of chlorine decay in water distribution systems. A recirculating loop of 6-inch diameter unlined ductile iron pipe was used to simulate turbulent flow conditions in a pipe with significant c...

System-level Analysis of Chilled Water Systems Aboard Naval Ships

DTIC Science & Technology

2015-06-24

developed one-dimensional partial differen- tial equation models that simulate time-dependent hy- drodynamics and heat transport in a piping network...Thermal zone extents. 2) Piping path and diameter. 3) Specifications and locations of chillers, heat ex- changers, pumps and valves. The framework of the... pipes and provides boundary conditions for the end of the connecting pipes . Pumps, valves, bends and heat exchangers are such components. These

Heat Transfer Modeling of an Annular On-Line Spray Water Cooling Process for Electric-Resistance-Welded Steel Pipe

PubMed Central

Chen, Zejun; Han, Huiquan; Ren, Wei; Huang, Guangjie

2015-01-01

On-line spray water cooling (OSWC) of electric-resistance-welded (ERW) steel pipes can replace the conventional off-line heat treatment process and become an important and critical procedure. The OSWC process improves production efficiency, decreases costs, and enhances the mechanical properties of ERW steel pipe, especially the impact properties of the weld joint. In this paper, an annular OSWC process is investigated based on an experimental simulation platform that can obtain precise real-time measurements of the temperature of the pipe, the water pressure and flux, etc. The effects of the modes of annular spray water cooling and related cooling parameters on the mechanical properties of the pipe are investigated. The temperature evolutions of the inner and outer walls of the pipe are measured during the spray water cooling process, and the uniformity of mechanical properties along the circumferential and longitudinal directions is investigated. A heat transfer coefficient model of spray water cooling is developed based on measured temperature data in conjunction with simulation using the finite element method. Industrial tests prove the validity of the heat transfer model of a steel pipe undergoing spray water cooling. The research results can provide a basis for the industrial application of the OSWC process in the production of ERW steel pipes. PMID:26201073

Heat Transfer Modeling of an Annular On-Line Spray Water Cooling Process for Electric-Resistance-Welded Steel Pipe.

PubMed

Chen, Zejun; Han, Huiquan; Ren, Wei; Huang, Guangjie

2015-01-01

On-line spray water cooling (OSWC) of electric-resistance-welded (ERW) steel pipes can replace the conventional off-line heat treatment process and become an important and critical procedure. The OSWC process improves production efficiency, decreases costs, and enhances the mechanical properties of ERW steel pipe, especially the impact properties of the weld joint. In this paper, an annular OSWC process is investigated based on an experimental simulation platform that can obtain precise real-time measurements of the temperature of the pipe, the water pressure and flux, etc. The effects of the modes of annular spray water cooling and related cooling parameters on the mechanical properties of the pipe are investigated. The temperature evolutions of the inner and outer walls of the pipe are measured during the spray water cooling process, and the uniformity of mechanical properties along the circumferential and longitudinal directions is investigated. A heat transfer coefficient model of spray water cooling is developed based on measured temperature data in conjunction with simulation using the finite element method. Industrial tests prove the validity of the heat transfer model of a steel pipe undergoing spray water cooling. The research results can provide a basis for the industrial application of the OSWC process in the production of ERW steel pipes.

Direct numerical simulation of turbulence in a bent pipe

NASA Astrophysics Data System (ADS)

Schlatter, Philipp; Noorani, Azad

2013-11-01

A series of direct numerical simulations of turbulent flow in a bent pipe is presented. The setup employs periodic (cyclic) boundary conditions in the axial direction, leading to a nominally infinitely long pipe. The discretisation is based on the high-order spectral element method, using the code Nek5000. Four different curvatures, defined as the ratio between pipe radius and coil radius, are considered: κ = 0 (straight), 0.01 (mild curvature), 0.1 and 0.3 (strong curvature), at bulk Reynolds numbers of up to 11700 (corresponding to Reτ = 360 in the straight pipe case). The result show the turbulence-reducing effect of the curvature (similar to rotation), leading close to relaminarisation in the inner side; the outer side, however, remains fully turbulent. Prpoer orthogonal decomposition (POD) is used to extract the dominant modes, in an effort to explain low-frequency switching of sides inside the pipe. A number of additional interesting features are explored, which include sub-straight and sub-laminar drag for specific choices of curvature and Reynolds number: In particular the case with sub-laminar drag is investigated further, and our analysis shows the existence of a spanwise wave in the bent pipe, which in fact leads to lower overall pressure drop.

Evolution of turbulence characteristics from straight to curved pipes

NASA Astrophysics Data System (ADS)

El Khoury, George K.; Noorani, Azad; Schlatter, Philipp; Fischer, Paul F.

2012-11-01

Large-scale direct numerical simulations are performed to study turbulent flow in straight and bent pipes at four different Reynolds numbers: Reb = 5300 , 11700 (bent and straight) and 19000 and 37700 (only straight). We consider a pipe of radius R and axial length 25 R with curvature parameter κ taken to be 0 , 0 . 01 and 0 . 1 for zero, mild and strong curvatures, respectively. The code used is Nek5000 based on the spectral element method. In the straight configuration, the obtained DNS data is carefully checked against other recent simulations, highlighting minute differences between the available data. Owing to a centrifugal instability mechanism, the flow in bent pipe (κ ≠ 0) develops counter-rotating vortices, so-called Dean vortices. The presence of the secondary motion thus induces substantial asymmetries both in the mean flow and turbulence characteristics for the bent pipe. These asymmetries tend to damp turbulence along the inner side and correspondingly enhance it along the upper side. The results are validated with recent experiments, and we could confirm the peculiar behaviour of the friction factor for specific curvatures and Re , leading to a lower friction in curved pipes than in straight pipes for the same mass flux.

Blocking performance of the hose model and the pipe model for VPN service provisioning over WDM optical networks

NASA Astrophysics Data System (ADS)

Wang, Haibo; Swee Poo, Gee

2004-08-01

We study the provisioning of virtual private network (VPN) service over WDM optical networks. For this purpose, we investigate the blocking performance of the hose model versus the pipe model for the provisioning. Two techniques are presented: an analytical queuing model and a discrete event simulation. The queuing model is developed from the multirate reduced-load approximation technique. The simulation is done with the OPNET simulator. Several experimental situations were used. The blocking probabilities calculated from the two approaches show a close match, indicating that the multirate reduced-load approximation technique is capable of predicting the blocking performance for the pipe model and the hose model in WDM networks. A comparison of the blocking behavior of the two models shows that the hose model has superior blocking performance as compared with pipe model. By and large, the blocking probability of the hose model is better than that of the pipe model by a few orders of magnitude, particularly at low load regions. The flexibility of the hose model allowing for the sharing of resources on a link among all connections accounts for its superior performance.

Analytical solution and numerical simulation of the liquid nitrogen freezing-temperature field of a single pipe

NASA Astrophysics Data System (ADS)

Cai, Haibing; Xu, Liuxun; Yang, Yugui; Li, Longqi

2018-05-01

Artificial liquid nitrogen freezing technology is widely used in urban underground engineering due to its technical advantages, such as simple freezing system, high freezing speed, low freezing temperature, high strength of frozen soil, and absence of pollution. However, technical difficulties such as undefined range of liquid nitrogen freezing and thickness of frozen wall gradually emerge during the application process. Thus, the analytical solution of the freezing-temperature field of a single pipe is established considering the freezing temperature of soil and the constant temperature of freezing pipe wall. This solution is then applied in a liquid nitrogen freezing project. Calculation results show that the radius of freezing front of liquid nitrogen is proportional to the square root of freezing time. The radius of the freezing front also decreases with decreased the freezing temperature, and the temperature gradient of soil decreases with increased distance from the freezing pipe. The radius of cooling zone in the unfrozen area is approximately four times the radius of the freezing front. Meanwhile, the numerical simulation of the liquid nitrogen freezing-temperature field of a single pipe is conducted using the Abaqus finite-element program. Results show that the numerical simulation of soil temperature distribution law well agrees with the analytical solution, further verifies the reliability of the established analytical solution of the liquid nitrogen freezing-temperature field of a single pipe.

Advanced thermal energy management: A thermal test bed and heat pipe simulation

NASA Technical Reports Server (NTRS)

Barile, Ronald G.

1986-01-01

Work initiated on a common-module thermal test simulation was continued, and a second project on heat pipe simulation was begun. The test bed, constructed from surplus Skylab equipment, was modeled and solved for various thermal load and flow conditions. Low thermal load caused the radiator fluid, Coolanol 25, to thicken due to its temperature avoided by using a regenerator-heat-exchanger. Other possible solutions modeled include a radiator heater and shunting heat from the central thermal bus to the radiator. Also, module air temperature can become excessive with high avionics load. A second preoject concerning advanced heat pipe concepts was initiated. A program was written which calculates fluid physical properties, liquid and vapor pressure in the evaporator and condenser, fluid flow rates, and thermal flux. The program is directed to evaluating newer heat pipe wicks and geometries, especially water in an artery surrounded by six vapor channels. Effects of temperature, groove and slot dimensions, and wick properties are reported.

Numerical simulation of water hammer in low pressurized pipe: comparison of SimHydraulics and Lax-Wendroff method with experiment

NASA Astrophysics Data System (ADS)

Himr, D.

2013-04-01

Article describes simulation of unsteady flow during water hammer with two programs, which use different numerical approaches to solve ordinary one dimensional differential equations describing the dynamics of hydraulic elements and pipes. First one is Matlab-Simulink-SimHydraulics, which is a commercial software developed to solve the dynamics of general hydraulic systems. It defines them with block elements. The other software is called HYDRA and it is based on the Lax-Wendrff numerical method, which serves as a tool to solve the momentum and continuity equations. This program was developed in Matlab by Brno University of Technology. Experimental measurements were performed on a simple test rig, which consists of an elastic pipe with strong damping connecting two reservoirs. Water hammer is induced with fast closing the valve. Physical properties of liquid and pipe elasticity parameters were considered in both simulations, which are in very good agreement and differences in comparison with experimental data are minimal.

Yield strength mapping in the cross section of ERW pipes considering kinematic hardening and residual stress

NASA Astrophysics Data System (ADS)

Kim, Dongwook; Quagliato, Luca; Lee, Wontaek; Kim, Naksoo

2017-09-01

In the ERW (electric resistance welding) pipe manufacturing, material properties, process conditions and settings strongly influences the mechanical performances of the final product, as well as they can make them to be not uniform and to change from point to point in the pipe. The present research work proposes an integrated numerical model for the study of the whole ERW process, considering roll forming, welding and sizing stations, allowing to infer the influence of the process parameters on the final quality of the pipe, in terms of final shape and residual stress. The developed numerical model has been initially validated comparing the dimensions of the pipe derived from the simulation results with those of industrial production, proving the reliability of the approach. Afterwards, by varying the process parameters in the numerical simulation, namely the roll speed, the sizing ratio and the friction factor, the influence on the residual stress in the pipe, at the end of the process and after each station, is studied and discussed along the paper.

Experimental operation of a sodium heat pipe

NASA Astrophysics Data System (ADS)

Holtz, R. E.; McLennan, G. A.; Koehl, E. R.

1985-05-01

This report documents the operation of a 28 in. long sodium heat pipe in the Heat Pipe Test Facility (HPTF) installed at Argonne National Laboratory. Experimental data were collected to simulate conditions prototypic of both a fluidized bed coal combustor application and a space environment application. Both sets of experiment data show good agreement with the heat pipe analytical model. The heat transfer performance of the heat pipe proved reliable over a substantial period of operation and over much thermal cycling. Additional testing of longer heat pipes under controlled laboratory conditions will be necessary to determine performance limitations and to complete the design code validation.

Branch-pipe-routing approach for ships using improved genetic algorithm

NASA Astrophysics Data System (ADS)

Sui, Haiteng; Niu, Wentie

2016-09-01

Branch-pipe routing plays fundamental and critical roles in ship-pipe design. The branch-pipe-routing problem is a complex combinatorial optimization problem and is thus difficult to solve when depending only on human experts. A modified genetic-algorithm-based approach is proposed in this paper to solve this problem. The simplified layout space is first divided into threedimensional (3D) grids to build its mathematical model. Branch pipes in layout space are regarded as a combination of several two-point pipes, and the pipe route between two connection points is generated using an improved maze algorithm. The coding of branch pipes is then defined, and the genetic operators are devised, especially the complete crossover strategy that greatly accelerates the convergence speed. Finally, simulation tests demonstrate the performance of proposed method.

Experimental testing and modeling analysis of solute mixing at water distribution pipe junctions.

PubMed

Shao, Yu; Jeffrey Yang, Y; Jiang, Lijie; Yu, Tingchao; Shen, Cheng

2014-06-01

Flow dynamics at a pipe junction controls particle trajectories, solute mixing and concentrations in downstream pipes. The effect can lead to different outcomes of water quality modeling and, hence, drinking water management in a distribution network. Here we have investigated solute mixing behavior in pipe junctions of five hydraulic types, for which flow distribution factors and analytical equations for network modeling are proposed. First, based on experiments, the degree of mixing at a cross is found to be a function of flow momentum ratio that defines a junction flow distribution pattern and the degree of departure from complete mixing. Corresponding analytical solutions are also validated using computational-fluid-dynamics (CFD) simulations. Second, the analytical mixing model is further extended to double-Tee junctions. Correspondingly the flow distribution factor is modified to account for hydraulic departure from a cross configuration. For a double-Tee(A) junction, CFD simulations show that the solute mixing depends on flow momentum ratio and connection pipe length, whereas the mixing at double-Tee(B) is well represented by two independent single-Tee junctions with a potential water stagnation zone in between. Notably, double-Tee junctions differ significantly from a cross in solute mixing and transport. However, it is noted that these pipe connections are widely, but incorrectly, simplified as cross junctions of assumed complete solute mixing in network skeletonization and water quality modeling. For the studied pipe junction types, analytical solutions are proposed to characterize the incomplete mixing and hence may allow better water quality simulation in a distribution network. Published by Elsevier Ltd.

Numerical and experimental investigation of strip deformation in cage roll forming process for pipes with low ratio of thickness/diameter

NASA Astrophysics Data System (ADS)

Kasaei, M. M.; Naeini, H. Moslemi; Tehrani, M. Salmani; Tafti, R. Azizi

2011-01-01

Cage roll forming is one of the advanced methods of cold roll forming process which is used widely for producing ERW pipes. In addition to decreasing the production cost and time, using cage roll forming provides smooth deformation on the strip. Few studies can be found about cage roll forming because of its complexity, and the available knowledge is experience-based more than science-based. In this paper, deformation of pipes with low ratio of thickness/diameter is investigated by 3D finite element simulation in Marc-Mentat software. Edge buckling defect in cage roll forming of low ratio of thickness/diameter pipes is very important. Due to direct influence of longitudinal strain on the edge buckling phenomenon, longitudinal strains at the edge and center line of the strip are investigated and high risk stands are introduced. The deformed strip is predicted using the simulation results and effects of each cage forming stage on the deformed strip profile are specified. In order to verify the simulation results, strip width and opening distance of the two edges in different forming stages are obtained from the simulations and compared with the experimental data which were measured from the production line. A good agreement between the experimental and simulated results is observed.

Pipe Flow Simulation Software: A Team Approach to Solve an Engineering Education Problem.

ERIC Educational Resources Information Center

Engel, Renata S.; And Others

1996-01-01

A computer simulation program for use in the study of fluid mechanics is described. The package is an interactive tool to explore the fluid flow characteristics of a pipe system by manipulating the physical construction of the system. The motivation, software design requirements, and specific details on how its objectives were met are presented.…

A PC-based high temperature gas reactor simulator for Indonesian conceptual HTR reactor basic training

NASA Astrophysics Data System (ADS)

Syarip; Po, L. C. C.

2018-05-01

In planning for nuclear power plant construction in Indonesia, helium cooled high temperature reactor (HTR) is favorable for not relying upon water supply that might be interrupted by earthquake. In order to train its personnel, BATAN has cooperated with Micro-Simulation Technology of USA to develop a 200 MWt PC-based simulation model PCTRAN/HTR. It operates in Win10 environment with graphic user interface (GUI). Normal operation of startup, power maneuvering, shutdown and accidents including pipe breaks and complete loss of AC power have been conducted. A sample case of safety analysis simulation to demonstrate the inherent safety features of HTR was done for helium pipe break malfunction scenario. The analysis was done for the variation of primary coolant pipe break i.e. from 0,1% - 0,5 % and 1% - 10 % helium gas leakages, while the reactor was operated at the maximum constant power of 10 MWt. The result shows that the highest temperature of HTR fuel centerline and coolant were 1150 °C and 1296 °C respectively. With 10 kg/s of helium flow in the reactor core, the thermal power will back to the startup position after 1287 s of helium pipe break malfunction.

Steel Fibers Reinforced Concrete Pipes - Experimental Tests and Numerical Simulation

NASA Astrophysics Data System (ADS)

Doru, Zdrenghea

2017-10-01

The paper presents in the first part a state of the art review of reinforced concrete pipes used in micro tunnelling realised through pipes jacking method and design methods for steel fibres reinforced concrete. In part two experimental tests are presented on inner pipes with diameters of 1410mm and 2200mm, and specimens (100x100x500mm) of reinforced concrete with metal fibres (35 kg / m3). In part two experimental tests are presented on pipes with inner diameters of 1410mm and 2200mm, and specimens (100x100x500mm) of reinforced concrete with steel fibres (35 kg / m3). The results obtained are analysed and are calculated residual flexural tensile strengths which characterise the post-cracking behaviour of steel fibres reinforced concrete. In the third part are presented numerical simulations of the tests of pipes and specimens. The model adopted for the pipes test was a three-dimensional model and loads considered were those obtained in experimental tests at reaching breaking forces. Tensile stresses determined were compared with mean flexural tensile strength. To validate tensile parameters of steel fibres reinforced concrete, experimental tests of the specimens were modelled with MIDAS program to reproduce the flexural breaking behaviour. To simulate post - cracking behaviour was used the method σ — ε based on the relationship stress - strain, according to RILEM TC 162-TDF. For the specimens tested were plotted F — δ diagrams, which have been superimposed for comparison with the similar diagrams of experimental tests. The comparison of experimental results with those obtained from numerical simulation leads to the following conclusions: - the maximum forces obtained by numerical calculation have higher values than the experimental values for the same tensile stresses; - forces corresponding of residual strengths have very similar values between the experimental and numerical calculations; - generally the numerical model estimates a breaking force greater than that obtained in the experimental tests. Experimental and numerical studies are used to establish the residual characteristic flexural tensile strength minimum guaranteed and limits of applicability of concrete pipes reinforced with steel fibres used in various field and loading situations.

A Study of Applying Pulsed Remote Field Eddy Current in Ferromagnetic Pipes Testing

PubMed Central

Luo, Qingwang; Shi, Yibing; Wang, Zhigang; Zhang, Wei; Li, Yanjun

2017-01-01

Pulsed Remote Field Eddy Current Testing (PRFECT) attracts the attention in the testing of ferromagnetic pipes because of its continuous spectrum. This paper simulated the practical PRFECT of pipes by using ANSYS software and employed Least Squares Support Vector Regression (LSSVR) to extract the zero-crossing time to analyze the pipe thickness. As a result, a secondary peak is found in zero-crossing time when transmitter passed by a defect. The secondary peak will lead to wrong quantification and the localization of defects, especially when defects are found only at the transmitter location. Aiming to eliminate the secondary peaks, double sensing coils are set in the transition zone and Wiener deconvolution filter is applied. In the proposed method, position dependent response of the differential signals from the double sensing coils is calibrated by employing zero-mean normalization. The methods proposed in this paper are validated by analyzing the simulation signals and can improve the practicality of PRFECT of ferromagnetic pipes. PMID:28475141

A Study of Applying Pulsed Remote Field Eddy Current in Ferromagnetic Pipes Testing.

PubMed

Luo, Qingwang; Shi, Yibing; Wang, Zhigang; Zhang, Wei; Li, Yanjun

2017-05-05

Pulsed Remote Field Eddy Current Testing (PRFECT) attracts the attention in the testing of ferromagnetic pipes because of its continuous spectrum. This paper simulated the practical PRFECT of pipes by using ANSYS software and employed Least Squares Support Vector Regression (LSSVR) to extract the zero-crossing time to analyze the pipe thickness. As a result, a secondary peak is found in zero-crossing time when transmitter passed by a defect. The secondary peak will lead to wrong quantification and the localization of defects, especially when defects are found only at the transmitter location. Aiming to eliminate the secondary peaks, double sensing coils are set in the transition zone and Wiener deconvolution filter is applied. In the proposed method, position dependent response of the differential signals from the double sensing coils is calibrated by employing zero-mean normalization. The methods proposed in this paper are validated by analyzing the simulation signals and can improve the practicality of PRFECT of ferromagnetic pipes.

Measuring a state of mind indicative of thriving using the Student Pharmacist Inventory of Professional Engagement (S-PIPE).

PubMed

Aronson, Benjamin D; Janke, Kristin K

2018-07-01

Professional engagement has importance to the professional of pharmacy, and in particular the growth of student pharmacists. Measurement of this construct would allow investigation of factors that may increase or decrease professional engagement. To describe the development of the Student Pharmacist Inventory of Professional Engagement (S-PIPE), assess the factor structure and convergent validity, and test for differences in professional engagement based upon demographic and background factors. Potential items for the S-PIPE were developed iteratively through inductive and deductive item-writing, 2 pilot administrations, expert review of items, and assessment of the content validity index, and cognitive interviews with students. The S-PIPE was administered to a cohort of 164 first year student pharmacists at University of Minnesota, along with items querying types and level of involvement in professional experiences and activities. An exploratory factor analysis was conducted using principal axis factoring extraction and Promax rotation. The number of factors to retain was based upon eigenvalues, examination of the scree plot, and a parallel analysis. Factors of the S-PIPE were compared to self-rated level of involvement and other demographic factors. Three factors were retained accounting for 70.7% of the variance, and named Belonging (α = 0.942, 9 items), Connectedness (α = 0.864, 3 items), and Meaningful Experience (α = 0.760, 4 items). All 3 factors were significantly correlated to self-rated involvement (r = 0.291 to 0.370). Level of professional engagement differed in this study by gender, and pharmacy work experience. This study lays the foundation for quantitative research in professional engagement among student pharmacists. Future work is needed to further validate and extend these findings. Copyright © 2017 Elsevier Inc. All rights reserved.

Investigation of erosion behavior in different pipe-fitting using Eulerian-Lagrangian approach

NASA Astrophysics Data System (ADS)

Kulkarni, Harshwardhan; Khadamkar, Hrushikesh; Mathpati, Channamallikarjun

2017-11-01

Erosion is a wear mechanism of piping system in which wall thinning occurs because of turbulent flow along with along with impact of solid particle on the pipe wall, because of this pipe ruptures causes costly repair of plant and personal injuries. In this study two way coupled Eulerian-Lagrangian approach is used to solve the liquid solid (water-ferrous suspension) flow in the different pipe fitting namely elbow, t-junction, reducer, orifice and 50% open gate valve. Simulations carried out using incomressible transient solver in OpenFOAM for different Reynolds's number (10k, 25k, 50k) and using WenYu drag model to find out possible higher erosion region in pipe fitting. Used transient solver is a hybrid in nature which is combination of Lagrangian library and pimpleFoam. Result obtained from simulation shows that exit region of elbow specially downstream of straight, extradose of the bend section more affected by erosion. Centrifugal force on solid particle at bend affect the erosion behavior. In case of t-junction erosion occurs below the locus of the projection of branch pipe on the wall. For the case of reducer, orifice and a gate valve reduction area as well as downstream is getting more affected by erosion because of increase in velocities.

Dynamic thermal characteristics of heat pipe via segmented thermal resistance model for electric vehicle battery cooling

NASA Astrophysics Data System (ADS)

Liu, Feifei; Lan, Fengchong; Chen, Jiqing

2016-07-01

Heat pipe cooling for battery thermal management systems (BTMSs) in electric vehicles (EVs) is growing due to its advantages of high cooling efficiency, compact structure and flexible geometry. Considering the transient conduction, phase change and uncertain thermal conditions in a heat pipe, it is challenging to obtain the dynamic thermal characteristics accurately in such complex heat and mass transfer process. In this paper, a ;segmented; thermal resistance model of a heat pipe is proposed based on thermal circuit method. The equivalent conductivities of different segments, viz. the evaporator and condenser of pipe, are used to determine their own thermal parameters and conditions integrated into the thermal model of battery for a complete three-dimensional (3D) computational fluid dynamics (CFD) simulation. The proposed ;segmented; model shows more precise than the ;non-segmented; model by the comparison of simulated and experimental temperature distribution and variation of an ultra-thin micro heat pipe (UMHP) battery pack, and has less calculation error to obtain dynamic thermal behavior for exact thermal design, management and control of heat pipe BTMSs. Using the ;segmented; model, the cooling effect of the UMHP pack with different natural/forced convection and arrangements is predicted, and the results correspond well to the tests.

Heat Pipes and Heat Rejection Component Testing at NASA Glenn Research Center

NASA Technical Reports Server (NTRS)

Sanzi, James L.; Jaworske, Donald A.

2012-01-01

Titanium-water heat pipes are being evaluated for use in the heat rejection system for space fission power systems. The heat rejection syst em currently comprises heat pipes with a graphite saddle and a composite fin. The heat input is a pumped water loop from the cooling of the power conversion system. The National Aeronautics and Space Administration has been life testing titanium-water heat pipes as well as eval uating several heat pipe radiator designs. The testing includes thermal modeling and verification of model, material compatibility, frozen startup of heat pipe radiators, and simulating low-gravity environments. Future thermal testing of titanium-water heat pipes includes low-g ravity testing of thermosyphons, radiation testing of heat pipes and fin materials, water pump performance testing, as well as Small Busine ss Innovation Research funded deliverable prototype radiator panels.

Investigation of propulsion system for large LNG ships

NASA Astrophysics Data System (ADS)

Sinha, R. P.; Nik, Wan Mohd Norsani Wan

2012-09-01

Requirements to move away from coal for power generation has made LNG as the most sought after fuel source, raising steep demands on its supply and production. Added to this scenario is the gradual depletion of the offshore oil and gas fields which is pushing future explorations and production activities far away into the hostile environment of deep sea. Production of gas in such environment has great technical and commercial impacts on gas business. For instance, laying gas pipes from deep sea to distant receiving terminals will be technically and economically challenging. Alternative to laying gas pipes will require installing re-liquefaction unit on board FPSOs to convert gas into liquid for transportation by sea. But, then because of increased distance between gas source and receiving terminals the current medium size LNG ships will no longer remain economical to operate. Recognizing this business scenario shipowners are making huge investments in the acquisition of large LNG ships. As power need of large LNG ships is very different from the current small ones, a variety of propulsion derivatives such as UST, DFDE, 2-Stroke DRL and Combined cycle GT have been proposed by leading engine manufacturers. Since, propulsion system constitutes major element of the ship's capital and life cycle cost, which of these options is most suited for large LNG ships is currently a major concern of the shipping industry and must be thoroughly assessed. In this paper the authors investigate relative merits of these propulsion options against the benchmark performance criteria of BOG disposal, fuel consumption, gas emissions, plant availability and overall life cycle cost.

Project Themis: PIV Measurement of Elbow Flow through a Flow Conditioner

DTIC Science & Technology

2011-12-01

validation of the component. CFD simulations, using LH2 , showed that the pipe with a VORTAB generated more vorticity at the exit than the pipe without a...using LH2 , showed that the pipe with a Vortab generated more vorticity at the exit than the pipe without a Vortab. PA#11932 4 Particle Image...number Fluid Vortab location Comment 9,000,000 LH2 9D USET installation 32,000 Air 9D For Validation Additional details • Fluent • k-ε

Finite Element Modeling of the World Federation's Second MFL Benchmark Problem

NASA Astrophysics Data System (ADS)

Zeng, Zhiwei; Tian, Yong; Udpa, Satish; Udpa, Lalita

2004-02-01

This paper presents results obtained by simulating the second magnetic flux leakage benchmark problem proposed by the World Federation of NDE Centers. The geometry consists of notches machined on the internal and external surfaces of a rotating steel pipe that is placed between two yokes that are part of a magnetic circuit energized by an electromagnet. The model calculates the radial component of the leaked field at specific positions. The nonlinear material property of the ferromagnetic pipe is taken into account in simulating the problem. The velocity effect caused by the rotation of the pipe is, however, ignored for reasons of simplicity.

Unified pipe network method for simulation of water flow in fractured porous rock

NASA Astrophysics Data System (ADS)

Ren, Feng; Ma, Guowei; Wang, Yang; Li, Tuo; Zhu, Hehua

2017-04-01

Rock masses are often conceptualized as dual-permeability media containing fractures or fracture networks with high permeability and porous matrix that is less permeable. In order to overcome the difficulties in simulating fluid flow in a highly discontinuous dual-permeability medium, an effective unified pipe network method is developed, which discretizes the dual-permeability rock mass into a virtual pipe network system. It includes fracture pipe networks and matrix pipe networks. They are constructed separately based on equivalent flow models in a representative area or volume by taking the advantage of the orthogonality of the mesh partition. Numerical examples of fluid flow in 2-D and 3-D domain including porous media and fractured porous media are presented to demonstrate the accuracy, robustness, and effectiveness of the proposed unified pipe network method. Results show that the developed method has good performance even with highly distorted mesh. Water recharge into the fractured rock mass with complex fracture network is studied. It has been found in this case that the effect of aperture change on the water recharge rate is more significant in the early stage compared to the fracture density change.

A theoretical and computational study of lithium-ion battery thermal management for electric vehicles using heat pipes

NASA Astrophysics Data System (ADS)

Greco, Angelo; Cao, Dongpu; Jiang, Xi; Yang, Hong

2014-07-01

A simplified one-dimensional transient computational model of a prismatic lithium-ion battery cell is developed using thermal circuit approach in conjunction with the thermal model of the heat pipe. The proposed model is compared to an analytical solution based on variable separation as well as three-dimensional (3D) computational fluid dynamics (CFD) simulations. The three approaches, i.e. the 1D computational model, analytical solution, and 3D CFD simulations, yielded nearly identical results for the thermal behaviours. Therefore the 1D model is considered to be sufficient to predict the temperature distribution of lithium-ion battery thermal management using heat pipes. Moreover, a maximum temperature of 27.6 °C was predicted for the design of the heat pipe setup in a distributed configuration, while a maximum temperature of 51.5 °C was predicted when forced convection was applied to the same configuration. The higher surface contact of the heat pipes allows a better cooling management compared to forced convection cooling. Accordingly, heat pipes can be used to achieve effective thermal management of a battery pack with confined surface areas.

Pipeline design and thermal stress analysis of a 10kW@20K helium refrigerator

NASA Astrophysics Data System (ADS)

Xu, D.; Gong, L. H.; Xu, P.; Liu, H. M.; Li, L. F.; Xu, X. D.

2014-01-01

This paper is based on the devices and pipeline in the horizontal cryogenic cold-box of a 10kW@20K helium refrigerator developed by Technical Institute of Physics and Chemistry, Chinese Academy of Sciences. Four devices, six valves, supporting components and pipe lines are positioned in the cold-box. At operating state, the temperature of these devices and pipeline is far below the room temperature, and the lowest temperature is 14K. Due to different material and temperature, the shrinkage of devices and pipes is different. Finite element analysis software SOLIDWORKS SIMULATION was used to numerically simulate the thermal stress and deformation. The results show that the thermal stress of pipe A is a little large. So we should change the pipe route or use a bellows expansion joint. Bellows expansion joints should also be used in the pipes connected to three of the six valves to protect them by decreasing the deformation. At last, the effect of diameter, thickness and bend radius on the thermal stress was analyzed. The results show that the thermal stress of the pipes increases with the increase of the diameter and the decrease of the bend radius.

Multicriteria optimization approach to design and operation of district heating supply system over its life cycle

NASA Astrophysics Data System (ADS)

Hirsch, Piotr; Duzinkiewicz, Kazimierz; Grochowski, Michał

2017-11-01

District Heating (DH) systems are commonly supplied using local heat sources. Nowadays, modern insulation materials allow for effective and economically viable heat transportation over long distances (over 20 km). In the paper a method for optimized selection of design and operating parameters of long distance Heat Transportation System (HTS) is proposed. The method allows for evaluation of feasibility and effectivity of heat transportation from the considered heat sources. The optimized selection is formulated as multicriteria decision-making problem. The constraints for this problem include a static HTS model, allowing considerations of system life cycle, time variability and spatial topology. Thereby, variation of heat demand and ground temperature within the DH area, insulation and pipe aging and/or terrain elevation profile are taken into account in the decision-making process. The HTS construction costs, pumping power, and heat losses are considered as objective functions. Inner pipe diameter, insulation thickness, temperatures and pumping stations locations are optimized during the decision-making process. Moreover, the variants of pipe-laying e.g. one pipeline with the larger diameter or two with the smaller might be considered during the optimization. The analyzed optimization problem is multicriteria, hybrid and nonlinear. Because of such problem properties, the genetic solver was applied.

Altitude Performance Characteristics of Tail-pipe Burner with Convergingconical Burner Section on J47 Turbojet Engine

NASA Technical Reports Server (NTRS)

Prince, William R; Mcaulay, John E

1950-01-01

An investigation of turbojet-engine thrust augmentation by means of tail-pipe burning was conducted in the NACA Lewis altitude wind tunnel. Performance data were obtained with a tail-pipe burner having a converging conical burner section installed on an axial-flow-compressor type turbojet engine over a range of simulated flight conditions and tail-pipe fuel-air ratios with a fixed-area exhaust nozzle. A maximum tail-pipe combustion efficiency of 0.86 was obtained at an altitude of 15,000 feet and a flight Mach number of 0.23. Tail-pipe burner operation was possible up to an altitude of 45,000 feet at a flight Mach number of 0.23.

A Corrosion Risk Assessment Model for Underground Piping

NASA Technical Reports Server (NTRS)

Datta, Koushik; Fraser, Douglas R.

2009-01-01

The Pressure Systems Manager at NASA Ames Research Center (ARC) has embarked on a project to collect data and develop risk assessment models to support risk-informed decision making regarding future inspections of underground pipes at ARC. This paper shows progress in one area of this project - a corrosion risk assessment model for the underground high-pressure air distribution piping system at ARC. It consists of a Corrosion Model of pipe-segments, a Pipe Wrap Protection Model; and a Pipe Stress Model for a pipe segment. A Monte Carlo simulation of the combined models provides a distribution of the failure probabilities. Sensitivity study results show that the model uncertainty, or lack of knowledge, is the dominant contributor to the calculated unreliability of the underground piping system. As a result, the Pressure Systems Manager may consider investing resources specifically focused on reducing these uncertainties. Future work includes completing the data collection effort for the existing ground based pressure systems and applying the risk models to risk-based inspection strategies of the underground pipes at ARC.

Petroleum service projects in the Gulf of Guinea

NASA Astrophysics Data System (ADS)

Ken-Worgu, Kenneth Chukwumeka

2011-07-01

The goal of this record of study is to examine the major facets involved in managing several petroleum service projects located in three different countries in the Gulf of Guinea simultaneously, while effectively engaging in business development activities for the Oil and Industrial Services Group (OIS). This work also furnishes adequate background on related subject matters to enable understanding of the projects presented. The petroleum services sector is the back bone of the oil and gas industry. Services companies are vital to the success of all petroleum and energy producers in the USA, the Gulf of Guinea and the world. There is a need and demand for these service companies because they play various roles such as logistics, drilling, construction, dredging, pipe laying, procurement, food supply, human resource supply, etc. The Gulf of Guinea comprises of countries from west and central Africa. This project was limited to Nigeria, Equatorial Guinea and Cameroon. This area holds the largest petroleum reserves in Africa and plays a vital role in the global supply of petroleum. The Oil and Industrial Services Group (OIS), plans to establish herself as one of the leading petroleum service companies in this gulf. To manage this expansion, I have taken the role of Gulf of Guinea manager to apply my background as a petroleum engineer as well as my business skills to build a successful division of the company. This work provides a record of study of the management of services, projects and contracts carried out by the OIS group in the gulf of Guinea. The following are the specific projects in the Gulf of Guinea that I participated in: Managing delivering, maintenance and marketing of offshore vessels, Offshore pipe laying project, Integrated pipeline maintenance project, Development a petroleum technical training facilities, Agbami pipe insulation project, Engineering lift project and Capital budgeting analysis for potential investments. The details of the specific tasks of the job, including objectives, description, managerial role, nontechnical aspects, approaches, information sources, discussions and contributions are projected in the body of this literature.

Preferential Concentration Of Solid Particles In Turbulent Horizontal Circular Pipe Flow

NASA Astrophysics Data System (ADS)

Kim, Jaehee; Yang, Kyung-Soo

2017-11-01

In particle-laden turbulent pipe flow, turbophoresis can lead to a preferential concentration of particles near the wall. To investigate this phenomenon, one-way coupled Direct Numerical Simulation (DNS) has been performed. Fully-developed turbulent pipe flow of the carrier fluid (air) is at Reτ = 200 based on the pipe radius and the mean friction velocity, whereas the Stokes numbers of the particles (solid) are St+ = 0.1 , 1 , 10 based on the mean friction velocity and the kinematic viscosity of the fluid. The computational domain for particle simulation is extended along the axial direction by duplicating the domain of the fluid simulation. By doing so, particle statistics in the spatially developing region as well as in the fully-developed region can be obtained. Accumulation of particles has been noticed at St+ = 1 and 10 mostly in the viscous sublayer, more intensive in the latter case. Compared with other authors' previous results, our results suggest that drag force on the particles should be computed by using an empirical correlation and a higher-order interpolation scheme even in a low-Re regime in order to improve the accuracy of particle simulation. This work was supported by the National Research Foundation of Korea (NRF) Grant funded by the Korea government (MSIP) (No. 2015R1A2A2A01002981).

Heat-pipe Earth.

PubMed

Moore, William B; Webb, A Alexander G

2013-09-26

The heat transport and lithospheric dynamics of early Earth are currently explained by plate tectonic and vertical tectonic models, but these do not offer a global synthesis consistent with the geologic record. Here we use numerical simulations and comparison with the geologic record to explore a heat-pipe model in which volcanism dominates surface heat transport. These simulations indicate that a cold and thick lithosphere developed as a result of frequent volcanic eruptions that advected surface materials downwards. Declining heat sources over time led to an abrupt transition to plate tectonics. Consistent with model predictions, the geologic record shows rapid volcanic resurfacing, contractional deformation, a low geothermal gradient across the bulk of the lithosphere and a rapid decrease in heat-pipe volcanism after initiation of plate tectonics. The heat-pipe Earth model therefore offers a coherent geodynamic framework in which to explore the evolution of our planet before the onset of plate tectonics.

Study of fatigue behavior of longitudinal welded pipes

NASA Astrophysics Data System (ADS)

Simion, P.; Dia, V.; Istrate, B.; Hrituleac, G.; Hrituleac, I.; Munteanu, C.

2016-08-01

During transport and storage of the various fluids, welded pipes are subjected to cyclic loading due to pressure fluctuations that often exceed the prescribed values for normal operation. These cyclic loading can significantly reduce the life of the pipes; as a result the design should be based on the fatigue strength not only on static resistance. In general the fatigue strength of pipes is dependent by strength, pipe geometry and surface quality. In case of the electric longitudinal welded pipes, the fatigue strength is significantly limited by concentration of residual stress and the size of existing defects in the weld seam. This paper presents the fatigue behaviour of the electric welded pipes by high frequency, under conditions that simulate real operating conditions pipes. Fatigue testing was performed on welded pipes made of micro alloyed carbon steels. Some of these pipes were previously subjected to a heat treatment of normalization, in order to also determine the influence of heat treatment on the fatigue strength of welded pipes. To determine and correlate the different factors affecting the fatigue strength, welded pipes were also subjected to various tests: tensile tests, impact tests, measurement of micro hardness, microstructural analysis by optical microscopy and scanning electron microscopy.

Modeling of efficient light extraction in light-pipes through specular surfaces with elliptical and lineal front shapes

NASA Astrophysics Data System (ADS)

Sánchez-Guerrero, Guillermo E.; Viera-González, Perla M.; Ceballos-Herrera, Daniel E.; Martínez-Guerra, Edgar

2016-09-01

Extraction light in light-pipes with different specular surfaces was analyzed. In the analysis, the impact of the surface shape in all properties of the extracted light in order to obtain an efficient extraction and a uniform illumination using a LED as light source. Also, several parameters of the specular surface to obtain spatial uniformity inside the light-pipe are considered. In this case, the simulation was made for a rectangular light­pipe. One objective of this work is to compare how the front face shape of the specular surface can affect the extraction of light in the lateral face of the light-pipe, only straight and elliptical front faces were used in this work and the comparison between them at different tilts and lengths were made. The main purpose of the front face was extract the light uniformly at the lateral face and this was done by studying simulations on OpticStudio Zemax. The results show how the extraction length is lower in the elliptical front but its total power performs better than the line front.

A simple hydrodynamic model of a laminar free-surface jet in horizontal or vertical flight

NASA Astrophysics Data System (ADS)

Haustein, Herman D.; Harnik, Ron S.; Rohlfs, Wilko

2017-08-01

A useable model for laminar free-surface jet evolution during flight, for both horizontal and vertical jets, is developed through joint analytical, experimental, and simulation methods. The jet's impingement centerline velocity, recently shown to dictate stagnation zone heat transfer, encompasses the entire flow history: from pipe-flow velocity profile development to profile relaxation and jet contraction during flight. While pipe-flow is well-known, an alternative analytic solution is presented for the centerline velocity's viscous-driven decay. Jet-contraction is subject to influences of surface tension (We), pipe-flow profile development, in-flight viscous dissipation (Re), and gravity (Nj = Re/Fr). The effects of surface tension and emergence momentum flux (jet thrust) are incorporated analytically through a global momentum balance. Though emergence momentum is related to pipe flow development, and empirically linked to nominal pipe flow-length, it can be modified to incorporate low-Re downstream dissipation as well. Jet contraction's gravity dependence is extended beyond existing uniform-velocity theory to cases of partially and fully developed profiles. The final jet-evolution model relies on three empirical parameters and compares well to present and previous experiments and simulations. Hence, micro-jet flight experiments were conducted to fill-in gaps in the literature: jet contraction under mild gravity-effects, and intermediate Reynolds and Weber numbers (Nj = 5-8, Re = 350-520, We = 2.8-6.2). Furthermore, two-phase direct numerical simulations provided insight beyond the experimental range: Re = 200-1800, short pipes (Z = L/d . Re ≥ 0.01), variable nozzle wettability, and cases of no surface tension and/or gravity.

Study on pipe deflection by using numerical method

NASA Astrophysics Data System (ADS)

Husaini; Zaki Mubarak, Amir; Agustiar, Rizki

2018-05-01

Piping systems are widely used in a refinery or oil and gas industry. The piping system must be properly designed to avoid failure or leakage. Pipe stress analysis is conducted to analyze the loads and critical stress occurred, so that the failure of the pipe can be avoided. In this research, it is analyzed the deflection of a pipe by using Finite Element Method. The pipe is made of A358 / 304SS SCH10S Stainless Steel. It is 16 inches in size with the distance between supports is 10 meters. The fluid flown is Liquid Natural Gas (LNG) with the range of temperature of -120 ° C to -170 ° C, and a density of 461.1 kg / m 3. The flow of LNG causes deflection of the pipe. The pipe deflection must be within the permissible tolerable range. The objective is to analyze the deflection occurred in the piping system. Based on the calculation and simulation, the deflection is 4.4983 mm, which is below the maximum limit of deflection allowed, which is 20.3 mm.

Water quality of flow through cured-in-place pipe (CIPP).

DOT National Transportation Integrated Search

2017-02-01

Though this study did not include replication, the preponderance of the data from field and simulated-field experiments indicates that Curedin- : Place Pipe (CIPP), with some care in enforcing the Caltrans specification and delaying the reintroductio...

Simulation and analysis on ultrasonic testing for the cement grouting defects of the corrugated pipe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qingbang, Han; Ling, Chen; Changping, Zhu

2014-02-18

The defects exist in the cement grouting process of prestressed corrugated pipe may directly impair the bridge safety. In this paper, sound fields propagation in concrete structures with corrugated pipes and the influence of various different defects are simulated and analyzed using finite element method. The simulation results demonstrate a much complex propagation characteristic due to multiple reflection, refraction and scattering, where the scattering signals caused by metal are very strong, while the signals scattered by an air bubble are weaker. The influence of defect both in time and frequency domain are found through deconvolution treatment. In the time domain,more » the deconvolution signals correspond to larger defect display a larger head wave amplitude and shorter arrive time than those of smaller defects; in the frequency domain, larger defect also shows a stronger amplitude, lower center frequency and lower cutoff frequency.« less

Transient simulation of hydropower station with consideration of three-dimensional unsteady flow in turbine

NASA Astrophysics Data System (ADS)

Huang, W. D.; Fan, H. G.; Chen, N. X.

2012-11-01

To study the interaction between the transient flow in pipe and the unsteady turbulent flow in turbine, a coupled model of the transient flow in the pipe and three-dimensional unsteady flow in the turbine is developed based on the method of characteristics and the fluid governing equation in the accelerated rotational relative coordinate. The load-rejection process under the closing of guide vanes of the hydraulic power plant is simulated by the coupled method, the traditional transient simulation method and traditional three-dimensional unsteady flow calculation method respectively and the results are compared. The pressure, unit flux and rotation speed calculated by three methods show a similar change trend. However, because the elastic water hammer in the pipe and the pressure fluctuation in the turbine have been considered in the coupled method, the increase of pressure at spiral inlet is higher and the pressure fluctuation in turbine is stronger.

Long titanium heat pipes for high-temperature space radiators

NASA Technical Reports Server (NTRS)

Girrens, S. P.; Ernst, D. M.

1982-01-01

Titanium heat pipes are being developed to provide light weight, reliable heat rejection devices as an alternate radiator design for the Space Reactor Power System (SP-100). The radiator design includes 360 heat pipes, each of which is 5.2 m long and dissipates 3 kW of power at 775 K. The radiator heat pipes use potassium as the working fluid, have two screen arteries for fluid return, a roughened surface distributive wicking system, and a D shaped cross section container configuration. A prototype titanium heat pipe, 5.5 m long, was fabricated and tested in space simulating conditions. Results from startup and isothermal operation tests are presented. These results are also compared to theoretical performance predictions that were used to design the heat pipe initially.

Long titanium heat pipes for high-temperature space radiators

NASA Technical Reports Server (NTRS)

Girrens, S. P.; Ernst, D. M.

1982-01-01

Titanium heat pipes are being developed to provide light weight, reliable heat rejection devices as an alternate radiator design for the Space Reactor Power System (SP-100). The radiator design includes 360 heat pipes, each of which is 5.2 m long and dissipates 3 kW of power at 775 K. The radiator heat pipes use potassium as the working fluid, have two screen arteries for fluid return, a roughened surface distributive wicking system, and a D-shaped cross-section container configuration. A prototype titanium heat pipe, 5.5-m long, has been fabricated and tested in space-simulating conditions. Results from startup and isothermal operation tests are presented. These results are also compared to theoretical performance predictions that were used to design the heat pipe initially.

Water quality of flow through cured-in-place pipe (CIPP) : final report.

DOT National Transportation Integrated Search

2017-02-01

Though this study did not include replication, the preponderance of the data from field and simulated-field experiments indicates that Curedin-Place : Pipe (CIPP), with some care in enforcing the Caltrans specification and delaying the reintroduction...

EPANET USERS MANUAL

EPA Science Inventory

EPANET is a computer program that performs extended period simulation of hydraulic and water quality behavior within drinking water distribution systems. It tracks the flow of water in each pipe, the pressure at each pipe junction, the height of water in each storage tank, and th...

Heat pipe fatigue test specimen: Metallurgical evaluation

NASA Technical Reports Server (NTRS)

Walak, Steven E.; Cronin, Michael J.; Grobstein, Toni

1992-01-01

An innovative creep/fatigue test was run to simulate the temperature, mechanical load, and sodium corrosion conditions expected in a heat pipe designed to supply thermal energy to a Stirling cycle power converter. A sodium-charged Inconel 718 heat pipe with a Nickel 200 screen wick was operated for 1090 hr at temperatures between 950 K (1250 F) and 1050 K (1430 F) while being subjected to creep and fatigue loads in a servo-hydraulic testing machine. After testing, the heat pipe was sectioned and examined using optical microscopy, scanning electron microscopy, and electron microprobe analysis with wavelength dispersive x-ray spectroscopy. The analysis concentrated on evaluating topographic, microstructural, and chemical changes in the sodium exposed surfaces of the heat pipe wall and wick. Surface changes in the evaporator, condenser, and adiabatic sections of the heat pipe were examined in an effort to correlate the changes with the expected sodium environment in the heat pipe. This report describes the setup, operating conditions, and analytical results of the sodium heat pipe fatigue test.

Heat Rejection Systems Utilizing Composites and Heat Pipes: Design and Performance Testing

NASA Technical Reports Server (NTRS)

Jaworske, Donald A.; Beach, Duane E.; Sanzi, James L.

2007-01-01

Polymer matrix composites offer the promise of reducing the mass and increasing the performance of future heat rejection systems. With lifetimes for heat rejection systems reaching a decade or more in a micrometeoroid environment, use of multiple heat pipes for fault tolerant design is compelling. The combination of polymer matrix composites and heat pipes is of particular interest for heat rejection systems operating on the lunar surface. A technology development effort is under way to study the performance of two radiator demonstration units manufactured with different polymer matrix composite face sheet resin and bonding adhesives, along with different titanium-water heat pipe designs. Common to the two radiator demonstration units is the use of high thermal conductivity fibers in the face sheets and high thermal conductivity graphite saddles within a light weight aluminum honeycomb core. Testing of the radiator demonstration units included thermal vacuum exposure and thermal vacuum exposure with a simulated heat pipe failure. Steady state performance data were obtained at different operating temperatures to identify heat transfer and thermal resistance characteristics. Heat pipe failure was simulated by removing the input power from an individual heat pipe in order to identify the diminished performance characteristics of the entire panel after a micrometeoroid strike. Freeze-thaw performance was also of interest. This paper presents a summary of the two radiator demonstration units manufactured to support this technology development effort along with the thermal performance characteristics obtained to date. Future work will also be discussed.

Experimental investigation and CFD simulation of multi-pipe earth-to-air heat exchangers (EAHEs) flow performance

NASA Astrophysics Data System (ADS)

Amanowicz, Łukasz; Wojtkowiak, Janusz

2017-11-01

In this paper the experimentally obtained flow characteristics of multi-pipe earth-to-air heat exchangers (EAHEs) were used to validate the EAHE flow performance numerical model prepared by means of CFD software Ansys Fluent. The cut-cell meshing and the k-ɛ realizable turbulence model with default coefficients values and enhanced wall treatment was used. The total pressure losses and airflow in each pipe of multi-pipe exchangers was investigated both experimentally and numerically. The results show that airflow in each pipe of multi-pipe EAHE structures is not equal. The validated numerical model can be used for a proper designing of multi-pipe EAHEs from the flow characteristics point of view. The influence of EAHEs geometrical parameters on the total pressure losses and airflow division between the exchanger pipes can be also analysed. Usage of CFD for designing the EAHEs can be helpful for HVAC engineers (Heating Ventilation and Air Conditioning) for optimizing the geometrical structure of multi-pipe EAHEs in order to save the energy and decrease operational costs of low-energy buildings.

A catchment-scale groundwater model including sewer pipe leakage in an urban system

NASA Astrophysics Data System (ADS)

Peche, Aaron; Fuchs, Lothar; Spönemann, Peter; Graf, Thomas; Neuweiler, Insa

2016-04-01

Keywords: pipe leakage, urban hydrogeology, catchment scale, OpenGeoSys, HYSTEM-EXTRAN Wastewater leakage from subsurface sewer pipe defects leads to contamination of the surrounding soil and groundwater (Ellis, 2002; Wolf et al., 2004). Leakage rates at pipe defects have to be known in order to quantify contaminant input. Due to inaccessibility of subsurface pipe defects, direct (in-situ) measurements of leakage rates are tedious and associated with a high degree of uncertainty (Wolf, 2006). Proposed catchment-scale models simplify leakage rates by neglecting unsaturated zone flow or by reducing spatial dimensions (Karpf & Krebs, 2013, Boukhemacha et al., 2015). In the present study, we present a physically based 3-dimensional numerical model incorporating flow in the pipe network, in the saturated zone and in the unsaturated zone to quantify leakage rates on the catchment scale. The model consists of the pipe network flow model HYSTEM-EXTAN (itwh, 2002), which is coupled to the subsurface flow model OpenGeoSys (Kolditz et al., 2012). We also present the newly developed coupling scheme between the two flow models. Leakage functions specific to a pipe defect are derived from simulations of pipe leakage using spatially refined grids around pipe defects. In order to minimize computational effort, these leakage functions are built into the presented numerical model using unrefined grids around pipe defects. The resulting coupled model is capable of efficiently simulating spatially distributed pipe leakage coupled with subsurficial water flow in a 3-dimensional environment. References: Boukhemacha, M. A., Gogu, C. R., Serpescu, I., Gaitanaru, D., & Bica, I. (2015). A hydrogeological conceptual approach to study urban groundwater flow in Bucharest city, Romania. Hydrogeology Journal, 23(3), 437-450. doi:10.1007/s10040-014-1220-3. Ellis, J. B., & Revitt, D. M. (2002). Sewer losses and interactions with groundwater quality. Water Science and Technology, 45(3), 195-202. itwh (2002). Modellbeschreibung, Institut für technisch-wissenschaftliche Hydrologie GmbH, Hannover. Karpf, C. & Krebs, P. (2013). Modelling of groundwater infiltration into sewer systems. Urban Water Journal, 10:4, 221-229, DOI: 10.1080/1573062X.2012.724077. Kolditz, O., Bauer, S. et al. (2012). OpenGeoSys: an open source initiative for numerical simulation of thermo-hydro-mechanical/chemical (THM/C) processes in porous media. Env. Earth Sci. 67(2):589-599. Wolf, L., Held, I., Eiswirth, M., & Hötzl, H. (2004). Impact of leaky sewers on groundwater quality. Acta Hydrochimica et Hydrobiologica, 32(4-5), 361-373. doi:10.1002/aheh.200400538. Wolf, L. (2006). Influence of leaky sewer systems on groundwater resources beneath the city of Rastatt, Germany. Dissertation, University of Karlsruhe.

Fatigue life calculation of desuperheater for solving pipe cracking issue using finite element method (FEM) software

NASA Astrophysics Data System (ADS)

Kumar, Aravinda; Singh, Jeetendra Kumar; Mohan, K.

2012-06-01

Desuperheater assembly experiences thermal cycling in operation by design. During power plant's start up, load change and shut down, thermal gradient is highest. Desuperheater should be able to handle rapid ramp up or ramp down of temperature in these operations. With "hump style" two nozzle desuperheater, cracks were appearing in the pipe after only few cycles of operation. From the field data, it was clear that desuperheater is not able to handle disproportionate thermal expansion happening in the assembly during temperature ramp up and ramp down in operation and leading to cracks appearing in the piping. Growth of thermal fatigue crack is influenced by several factors including geometry, severity of thermal stress and applied mechanical load. This paper seeks to determine cause of failure of two nozzle "hump style" desuperheater using Finite Element Method (FEM) simulation technique. Thermal stress simulation and fatigue life calculation were performed using commercial FEA software "ANSYS" [from Ansys Inc, USA]. Simulation result showed that very high thermal stress is developing in the region where cracks are seen in the field. From simulation results, it is also clear that variable thermal expansion of two nozzle studs is creating high stress at the water manifold junction. A simple and viable solution is suggested by increasing the length of the manifold which solved the cracking issues in the pipe.

An evaluation of training for lay providers in the use of Motivational Interviewing to promote academic achievement among urban youth

PubMed Central

Simon, Patricia; Ward, Nadia L.

2015-01-01

This study examined training outcomes for lay service providers who participated in a Motivational Interviewing (MI) training program designed to help increase intrinsic motivation and academic achievement among urban low-income and minority youth. Seventeen lay academic advisors received 16 hours of training in MI. Two, two-hour booster sessions plus five, two- hour weekly group supervision sessions were conducted with lay advisors over a period of seven months. One-hundred percent of lay advisors (n =17) participated in all training, booster sessions and assessments. Seventy-one percent of lay advisors (n=12) completed all group supervision sessions and submitted tapes for review. MI training was associated with increased knowledge of MI principles among lay service providers; increased proficiency in responding to simulated clients in an MI consistent style; increased use of MI adherent behaviors in sessions with real clients and maintenance of high motivation to use MI from pretest to posttest. Although lay advisors increased their knowledge of MI, further training is required for advisors to increase competence in delivering MI. Overall, Implications for using MI in the context of school-based settings is discussed. PMID:26356248

An evaluation of training for lay providers in the use of Motivational Interviewing to promote academic achievement among urban youth.

PubMed

Simon, Patricia; Ward, Nadia L

This study examined training outcomes for lay service providers who participated in a Motivational Interviewing (MI) training program designed to help increase intrinsic motivation and academic achievement among urban low-income and minority youth. Seventeen lay academic advisors received 16 hours of training in MI. Two, two-hour booster sessions plus five, two- hour weekly group supervision sessions were conducted with lay advisors over a period of seven months. One-hundred percent of lay advisors (n =17) participated in all training, booster sessions and assessments. Seventy-one percent of lay advisors (n=12) completed all group supervision sessions and submitted tapes for review. MI training was associated with increased knowledge of MI principles among lay service providers; increased proficiency in responding to simulated clients in an MI consistent style; increased use of MI adherent behaviors in sessions with real clients and maintenance of high motivation to use MI from pretest to posttest. Although lay advisors increased their knowledge of MI, further training is required for advisors to increase competence in delivering MI. Overall, Implications for using MI in the context of school-based settings is discussed.

THE EPANET WATER DISTRIBUTION SYSTEM MODEL

EPA Science Inventory

EPANET is a Windows program that performs extended period simulation of hydraulic and water-quality behavior within pressurized pipe networks. It tracks the flow of water in each pipe, the pressure at each node, the height of water in each tank, and the concentration of a chemica...

Heat Transfer Study for HTS Power Transfer Cables

NASA Technical Reports Server (NTRS)

Augustynowicz, S.; Fesmire, J.

2002-01-01

Thermal losses are a key factor in the successful application of high temperature superconducting (HTS) power cables. Existing concepts and prototypes rely on the use of multilayer insulation (MLI) systems that are subject to large variations in actual performance. The small space available for the thermal insulation materials makes the application even more difficult because of bending considerations, mechanical loading, and the arrangement between the inner and outer piping. Each of these mechanical variables affects the heat leak rate. These factors of bending and spacing are examined in this study. Furthermore, a maintenance-free insulation system (high vacuum level for 20 years or longer) is a practical requirement. A thermal insulation system simulating a section of a flexible FITS power cable was constructed for test and evaluation on a research cryostat. This paper gives experimental data for the comparison of ideal MLI, MLI on rigid piping, and MLI between flexible piping. A section of insulated flexible piping was tested under cryogenic vacuum conditions including simulated bending and spacers.

Separation dynamics of dense dispersions in laminar pipe flows: An experimental and numerical study

NASA Astrophysics Data System (ADS)

Voulgaropoulos, Victor; Jamshidi, Rashid; Zainal Abidin, M. I. I.; Angeli, Panagiota

2017-11-01

The physical mechanisms governing the separation of dense liquid dispersed flows in pipes are not well understood. In this work, both experiments and numerical simulations are performed to investigate these mechanisms. Liquid-liquid dispersions are generated using a static mixer and their evolution is studied along a horizontal pipe (26mm ID) at laminar flow and input dispersed phase volume fractions up to 50%. To conduct optical measurements (PLIF and PIV) in the dense dispersions, the refractive index of both liquids is matched. Measurements are carried out at two axial locations downstream the mixer (15D and 135D, where D is the pipe diameter). Homogeneous dispersions, observed at 15D, segregate at 135D. The packing of the drops results in asymmetric velocity profiles and high slip velocities. The mixture approach is used in the numerical simulations, including gravity and shear-induced diffusion of drops. The predictions on separation and on velocity fields agree well with the experiments. Research funded by Chevron.

UOE Pipe Numerical Model: Manufacturing Process And Von Mises Residual Stresses Resulted After Each Technological Step

NASA Astrophysics Data System (ADS)

Delistoian, Dmitri; Chirchor, Mihael

2017-12-01

Fluid transportation from production areas to final customer is effectuated by pipelines. For oil and gas industry, pipeline safety and reliability represents a priority. From this reason, pipe quality guarantee directly influence pipeline designed life, but first of all protects environment. A significant number of longitudinally welded pipes, for onshore/offshore pipelines, are manufactured by UOE method. This method is based on cold forming. In present study, using finite element method is modeled UOE pipe manufacturing process and is obtained von Mises stresses for each step. Numerical simulation is performed for L415 MB (X60) steel plate with 7,9 mm thickness, length 30 mm and width 1250mm, as result it is obtained a DN 400 pipe.

Determination of optimal tool parameters for hot mandrel bending of pipe elbows

NASA Astrophysics Data System (ADS)

Tabakajew, Dmitri; Homberg, Werner

2018-05-01

Seamless pipe elbows are important components in mechanical, plant and apparatus engineering. Typically, they are produced by the so-called `Hamburg process'. In this hot forming process, the initial pipes are subsequently pushed over an ox-horn-shaped bending mandrel. The geometric shape of the mandrel influences the diameter, bending radius and wall thickness distribution of the pipe elbow. This paper presents the numerical simulation model of the hot mandrel bending process created to ensure that the optimum mandrel geometry can be determined at an early stage. A fundamental analysis was conducted to determine the influence of significant parameters on the pipe elbow quality. The chosen methods and approach as well as the corresponding results are described in this paper.

Analysis of collapse in flattening a micro-grooved heat pipe by lateral compression

NASA Astrophysics Data System (ADS)

Li, Yong; He, Ting; Zeng, Zhixin

2012-11-01

The collapse of thin-walled micro-grooved heat pipes is a common phenomenon in the tube flattening process, which seriously influences the heat transfer performance and appearance of heat pipe. At present, there is no other better method to solve this problem. A new method by heating the heat pipe is proposed to eliminate the collapse during the flattening process. The effectiveness of the proposed method is investigated through a theoretical model, a finite element(FE) analysis, and experimental method. Firstly, A theoretical model based on a deformation model of six plastic hinges and the Antoine equation of the working fluid is established to analyze the collapse of thin walls at different temperatures. Then, the FE simulation and experiments of flattening process at different temperatures are carried out and compared with theoretical model. Finally, the FE model is followed to study the loads of the plates at different temperatures and heights of flattened heat pipes. The results of the theoretical model conform to those of the FE simulation and experiments in the flattened zone. The collapse occurs at room temperature. As the temperature increases, the collapse decreases and finally disappears at approximately 130 °C for various heights of flattened heat pipes. The loads of the moving plate increase as the temperature increases. Thus, the reasonable temperature for eliminating the collapse and reducing the load is approximately 130 °C. The advantage of the proposed method is that the collapse is reduced or eliminated by means of the thermal deformation characteristic of heat pipe itself instead of by external support. As a result, the heat transfer efficiency of heat pipe is raised.

Direct numerical simulation of turbulent pipe flow using the lattice Boltzmann method

NASA Astrophysics Data System (ADS)

Peng, Cheng; Geneva, Nicholas; Guo, Zhaoli; Wang, Lian-Ping

2018-03-01

In this paper, we present a first direct numerical simulation (DNS) of a turbulent pipe flow using the mesoscopic lattice Boltzmann method (LBM) on both a D3Q19 lattice grid and a D3Q27 lattice grid. DNS of turbulent pipe flows using LBM has never been reported previously, perhaps due to inaccuracy and numerical stability associated with the previous implementations of LBM in the presence of a curved solid surface. In fact, it was even speculated that the D3Q19 lattice might be inappropriate as a DNS tool for turbulent pipe flows. In this paper, we show, through careful implementation, accurate turbulent statistics can be obtained using both D3Q19 and D3Q27 lattice grids. In the simulation with D3Q19 lattice, a few problems related to the numerical stability of the simulation are exposed. Discussions and solutions for those problems are provided. The simulation with D3Q27 lattice, on the other hand, is found to be more stable than its D3Q19 counterpart. The resulting turbulent flow statistics at a friction Reynolds number of Reτ = 180 are compared systematically with both published experimental and other DNS results based on solving the Navier-Stokes equations. The comparisons cover the mean-flow profile, the r.m.s. velocity and vorticity profiles, the mean and r.m.s. pressure profiles, the velocity skewness and flatness, and spatial correlations and energy spectra of velocity and vorticity. Overall, we conclude that both D3Q19 and D3Q27 simulations yield accurate turbulent flow statistics. The use of the D3Q27 lattice is shown to suppress the weak secondary flow pattern in the mean flow due to numerical artifacts.

Military Hydrology. Report 20. Reservoir Outflow (RESOUT) Model

DTIC Science & Technology

1991-04-01

and/or be withdrawn from the river at some distance below the dam . In other cases, the outlet works discharges directly into a canal or pipe conveyance... dams are cited in Table 3 (USAGE 1965). 150. Darcy-Weisbach eguation, The head loss resulting from pipe fric- tion may also be determined using the Darcy... dam breach and computes the resulting outflow hydrograph. Example 8 Dam Breach Simulation ID Example 8 ID Dam Breach Simulation ID 10 1 0 KK Teton CG

A Search for Cosmic String Loops Using GADGET-2 Cosmological N-Body Simulator

NASA Astrophysics Data System (ADS)

Braverman, William; Cousins, Bryce; Jia, Hewei

2018-01-01

Cosmic string loops are an extremely elusive hypothetical entity that have eluded the grasp of physicists and astronomers since their existence was postulated in the 1970’s. Finding evidence of their existence could be the first empirical evidence of string theory.Simulating their basic motion in a cold dark matter background using GADGET-2 allows us to predict where they may cluster during large scale structure formation (if they cluster at all). Here, we present our progress in placing cosmic strings into GADGET-2 with their basic equations of motion to lay a ground work for more complex simulations to find where these strings cluster. Ultimately, these simulations could lay a groundwork as to where future microlensing and gravitational wave observatories should look for cosmic strings.

Better Water Demand and Pipe Description Improve the Distribution Network Modeling Results

EPA Science Inventory

Distribution system modeling simplifies pipe network in skeletonization and simulates the flow and water quality by using generalized water demand patterns. While widely used, the approach has not been examined fully on how it impacts the modeling fidelity. This study intends to ...

Reservoir simulation with MUFITS code: Extension for double porosity reservoirs and flows in horizontal wells

NASA Astrophysics Data System (ADS)

Afanasyev, Andrey

2017-04-01

Numerical modelling of multiphase flows in porous medium is necessary in many applications concerning subsurface utilization. An incomplete list of those applications includes oil and gas fields exploration, underground carbon dioxide storage and geothermal energy production. The numerical simulations are conducted using complicated computer programs called reservoir simulators. A robust simulator should include a wide range of modelling options covering various exploration techniques, rock and fluid properties, and geological settings. In this work we present a recent development of new options in MUFITS code [1]. The first option concerns modelling of multiphase flows in double-porosity double-permeability reservoirs. We describe internal representation of reservoir models in MUFITS, which are constructed as a 3D graph of grid blocks, pipe segments, interfaces, etc. In case of double porosity reservoir, two linked nodes of the graph correspond to a grid cell. We simulate the 6th SPE comparative problem [2] and a five-spot geothermal production problem to validate the option. The second option concerns modelling of flows in porous medium coupled with flows in horizontal wells that are represented in the 3D graph as a sequence of pipe segments linked with pipe junctions. The well completions link the pipe segments with reservoir. The hydraulics in the wellbore, i.e. the frictional pressure drop, is calculated in accordance with Haaland's formula. We validate the option against the 7th SPE comparative problem [3]. We acknowledge financial support by the Russian Foundation for Basic Research (project No RFBR-15-31-20585). References [1] Afanasyev, A. MUFITS Reservoir Simulation Software (www.mufits.imec.msu.ru). [2] Firoozabadi A. et al. Sixth SPE Comparative Solution Project: Dual-Porosity Simulators // J. Petrol. Tech. 1990. V.42. N.6. P.710-715. [3] Nghiem L., et al. Seventh SPE Comparative Solution Project: Modelling of Horizontal Wells in Reservoir Simulation // SPE Symp. Res. Sim., 1991. DOI: 10.2118/21221-MS.

The flows structure in unsteady gas flow in pipes with different cross-sections

NASA Astrophysics Data System (ADS)

Plotnikov, Leonid; Nevolin, Alexandr; Nikolaev, Dmitrij

2017-10-01

The results of numerical simulation and experimental study of the structure of unsteady flows in pipes with different cross sections are presented in the article. It is shown that the unsteady gas flow in a circular pipe is axisymmetric without secondary currents. Steady vortex structures (secondary flows) are observed in pipes with cross sections in the form of a square and an equilateral triangle. It was found that these secondary flows have a significant impact on gas flows in pipes of complex configuration. On the basis of experimental researches it is established that the strong oscillatory phenomena exist in the inlet pipe of the piston engine arising after the closing of the intake valve. The placement of the profiled plots (with a cross section of a square or an equilateral triangle) in the intake pipe leads to the damping of the oscillatory phenomena and a more rapid stabilization of pulsating flow. This is due to the stabilizing effect of the vortex structures formed in the corners of this configuration.

Strain Modal Analysis of Small and Light Pipes Using Distributed Fibre Bragg Grating Sensors

PubMed Central

Huang, Jun; Zhou, Zude; Zhang, Lin; Chen, Juntao; Ji, Chunqian; Pham, Duc Truong

2016-01-01

Vibration fatigue failure is a critical problem of hydraulic pipes under severe working conditions. Strain modal testing of small and light pipes is a good option for dynamic characteristic evaluation, structural health monitoring and damage identification. Unique features such as small size, light weight, and high multiplexing capability enable Fibre Bragg Grating (FBG) sensors to measure structural dynamic responses where sensor size and placement are critical. In this paper, experimental strain modal analysis of pipes using distributed FBG sensors ispresented. Strain modal analysis and parameter identification methods are introduced. Experimental strain modal testing and finite element analysis for a cantilever pipe have been carried out. The analysis results indicate that the natural frequencies and strain mode shapes of the tested pipe acquired by FBG sensors are in good agreement with the results obtained by a reference accelerometer and simulation outputs. The strain modal parameters of a hydraulic pipe were obtained by the proposed strain modal testing method. FBG sensors have been shown to be useful in the experimental strain modal analysis of small and light pipes in mechanical, aeronautic and aerospace applications. PMID:27681728

Real time control and numerical simulation of pipeline subjected to landslide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cuscuna, S.; Giusti, G.; Gramola, C.

1984-06-01

This paper describes SNAM research activity in the study of behaviour and real-time control of pipelines in landslide areas. The subject can be delt considering three different aspects: 1. Geotechnical characterization of unstable soils. The mechanical parameters of soil and the landslide types are defined; 2. Structural analysis of pipe-soil system. By means of a finite element program it's possible to study the pipe-soil interaction; in this numerical code the soil parameters attend by the non-linear elastic behaviour of pipe restraints. The results of this analysis are the location of the expected most stressed sections of pipe and the globalmore » behaviour of pipe inside the soil. 3. Instrumental control. The adoption of a suitable appliance of vibrating wire strain gauges allows the strain control of pipe in time. The aim is to make possible timely interventions in order to guarantee the installation safety.« less

Laying the Foundation for Successful Team Performance Trajectories: The Roles of Team Charters and Performance Strategies

ERIC Educational Resources Information Center

Mathieu, John E.; Rapp, Tammy L.

2009-01-01

This study examined the influences of team charters and performance strategies on the performance trajectories of 32 teams of master's of business administration students competing in a business strategy simulation over time. The authors extended existing theory on team development by demonstrating that devoting time to laying a foundation for…

A numerical analysis of high-temperature heat pipe startup from the frozen state

NASA Technical Reports Server (NTRS)

Cao, Y.; Faghri, A.

1993-01-01

Continuum and rarefied vapor flows co-exist along the heat pipe length for most of the startup period. A two-region model is proposed in which the vapor flow in the continuum region is modeled by the compressible Navier-Stokes equations, and the vapor flow in the rarefied region is simulated by a self-diffusion model. The two vapor regions are linked with appropriate boundary conditions, and heat pipe wail, wick, and vapor flow are solved as a conjugate problem. The numerical solutions for the entire heat pipe startup process from the frozen state are compared with the corresponding experimental data with good agreement.

Analytical simulation of nonlinear response to seismic test excitations of HDR-VKL (Heissdampfreaktor-Versuchskreislauf) piping system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Srinivasan, M.G.; Kot, C.A.; Mojtahed, M.

The paper describes the analytical modeling, calculations, and results of the posttest nonlinear simulation of high-level seismic testing of the VKL piping system at the HDR Test Facility in Germany. One of the objectives of the tests was to evaluate analytical methods for calculating the nonlinear response of realistic piping systems subjected to high-level seismic excitation that would induce significant plastic deformation. Two out of the six different pipe-support configurations, (ranging from a stiff system with struts and snubbers to a very flexible system with practically no seismic supports), subjected to simulated earthquakes, were tested at very high levels. Themore » posttest nonlinear calculations cover the KWU configuration, a reasonably compliant system with only rigid struts. Responses for 800% safe-shutdown-earthquake loading were calculated using the NONPIPE code. The responses calculated with NONPIPE were found generally to have the same time trends as the measurements but contained under-, over-, and correct estimates of peak values, almost in equal proportions. The only exceptions were the peak strut forces, which were underestimated as a group. The scatter in the peak value estimate of displacements and strut forces was smaller than that for the strains. The possible reasons for the differences and the effort on further analysis are discussed.« less

Altitude-wind-tunnel investigation of tail-pipe burning with a Westinghouse X24C-4B axial-flow turbojet engine

NASA Technical Reports Server (NTRS)

Fleming, William A; Wallner, Lewis E

1948-01-01

Thrust augmentation of an axial-flow type turbojet engine by burning fuel in the tail pipe has been investigated in the NACA Cleveland altitude wind tunnel. The performance was determined over a range of simulated flight conditions and tail-pipe fuel flows. The engine tail pipe was modified for the investigation to reduce the gas velocity at the inlet of the tail-pipe combustion chamber and to provide an adequate seat for the flame; four such modifications were investigated. The highest net-thrust increase obtained in the investigation was 86 percent with a net thrust specific fuel consumption of 2.91 and a total fuel-air ratio of 0.0523. The highest combustion efficiencies obtained with the four configurations ranged from 0.71 to 0.96. With three of the tail-pipe burners, for which no external cooling was provided, the exhaust nozzle and the rear part of the burner section were bright red during operation at high tail-pipe fuel-air ratios. With the tail-pipe burner for which fuel and water cooling were provided, the outer shell of the tail-pipe burner showed no evidence of elevated temperatures at any operating condition.

Glass light pipes for solar concentration

NASA Astrophysics Data System (ADS)

Madsen, C. K.; Dogan, Y.; Morrison, M.; Hu, C.; Atkins, R.

2018-02-01

Glass waveguides are fabricated using laser processing techniques that have low optical loss with >90% optical throughput. Advanced light pipes are demonstrated, including angled facets for turning mirrors used for lens-to-light pipe coupling, tapers that increase the concentration, and couplers for combining the outputs from multiple lens array elements. Because they are fabricated from glass, these light pipes can support large optical concentrations and propagate broadband solar over long distances with minimal loss and degradation compared to polymer waveguides. Applications include waveguiding solar concentrators using multi-junction PV cells, solar thermal applications and remoting solar energy, such as for daylighting. Ray trace simulations are used to estimate the surface smoothness required to achieve low loss. Optical measurements for fabricated light pipes are reported for use in waveguiding solar concentrator architectures.

Physics of heat pipe rewetting

NASA Technical Reports Server (NTRS)

Chan, S. H.

1994-01-01

This is the final report which summarizes the research accomplishments under the project entitled 'Physics of Heat Pipe Rewetting' under NASA Grant No. NAG 9-525, Basic, during the period of April 1, 1991 to January 31, 1994. The objective of the research project was to investigate both analytically and experimentally the rewetting characteristics of the heated, grooved plate. The grooved plate is to simulate the inner surface of the vapor channel in monogroove heat pipes for space station design. In such designs, the inner surface of the vapor channel is threaded with monogrooves. When the heat pipe is thermally overloaded, dryout of the monogroove surface occurs. Such a dryout surface should be promptly rewetted to prevent the failure of the heat pipe operation in the thermal radiator of the space station.

A novel simulation theory and model system for multi-field coupling pipe-flow system

NASA Astrophysics Data System (ADS)

Chen, Yang; Jiang, Fan; Cai, Guobiao; Xu, Xu

2017-09-01

Due to the lack of a theoretical basis for multi-field coupling in many system-level models, a novel set of system-level basic equations for flow/heat transfer/combustion coupling is put forward. Then a finite volume model of quasi-1D transient flow field for multi-species compressible variable-cross-section pipe flow is established by discretising the basic equations on spatially staggered grids. Combining with the 2D axisymmetric model for pipe-wall temperature field and specific chemical reaction mechanisms, a finite volume model system is established; a set of specific calculation methods suitable for multi-field coupling system-level research is structured for various parameters in this model; specific modularisation simulation models can be further derived in accordance with specific structures of various typical components in a liquid propulsion system. This novel system can also be used to derive two sub-systems: a flow/heat transfer two-field coupling pipe-flow model system without chemical reaction and species diffusion; and a chemical equilibrium thermodynamic calculation-based multi-field coupling system. The applicability and accuracy of two sub-systems have been verified through a series of dynamic modelling and simulations in earlier studies. The validity of this system is verified in an air-hydrogen combustion sample system. The basic equations and the model system provide a unified universal theory and numerical system for modelling and simulation and even virtual testing of various pipeline systems.

Studies on Single-phase and Multi-phase Heat Pipe for LED Panel for Efficient Heat Dissipation

NASA Astrophysics Data System (ADS)

Vyshnave, K. C.; Rohit, G.; Maithreya, D. V. N. S.; Rakesh, S. G.

2017-08-01

The popularity of LED panel as a source of illumination has soared recently due to its high efficiency. However, the removal of heat that is produced in the chip is still a major challenge in its design since this has an adverse effect on its reliability. If high junction temperature develops, the colour of the emitted light may diminish over prolonged usage or even a colour shift may occur. In this paper, a solution has been developed to address this problem by using a combination of heat pipe and heat fin technology. A single-phase and a two-phase heat pipes have been designed theoretically and computational simulations carried out using ANSYS FLUENT. The results of the theoretical calculations and those obtained from the simulations are found to be in agreement with each other.

Intrusion of Soil Water through Pipe Cracks

EPA Science Inventory

This report describes a series of experiments conducted at U.S. EPA’s Test and Evaluation Facility in 2013-2014 to study the intrusion of contaminated soil water into a pipe crack during simulated backflow events. A test rig was used consisting of a 3’ x 3’ x 3’ acrylic soil bo...

Large Eddy Simulation of Turbulent Flow in a Ribbed Pipe

NASA Astrophysics Data System (ADS)

Kang, Changwoo; Yang, Kyung-Soo

2011-11-01

Turbulent flow in a pipe with periodically wall-mounted ribs has been investigated by large eddy simulation with a dynamic subgrid-scale model. The value of Re considered is 98,000, based on hydraulic diameter and mean bulk velocity. An immersed boundary method was employed to implement the ribs in the computational domain. The spacing of the ribs is the key parameter to produce the d-type, intermediate and k-type roughness flows. The mean velocity profiles and turbulent intensities obtained from the present LES are in good agreement with the experimental measurements currently available. Turbulence statistics, including budgets of the Reynolds stresses, were computed, and analyzed to elucidate turbulence structures, especially around the ribs. In particular, effects of the ribs are identified by comparing the turbulence structures with those of smooth pipe flow. The present investigation is relevant to the erosion/corrosion that often occurs around a protruding roughness in a pipe system. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2010-0008457).

Performance of fuel system at different diesel temperature

NASA Astrophysics Data System (ADS)

Xu, Xiaoyong; Li, Xiaolu; Sun, Zai

2010-08-01

This paper presents the findings about performance of the fuel system of a diesel engine at different diesel temperature obtained through simulation and experiment. It can be seen from these findings that at the same rotational speed of fuel pump, the initial pressure in the fuel pipe remain unchanged as the fuel temperature increases, the peak pressure at the side of fuel pipe near the injector delays, and its largest value of pressure decreases. Meanwhile, at the same temperature, as the rotational speed increases, the initial pressure of fuel pipe is also essentially the same, the arrival of its peaks delays, and its largest value of pressure increases. The maximum fuel pressure at the side of fuel pipe near the injector has an increase of 28.9 %, 22.3%, and 13.9% respectively than the previous ones according to its conditions. At the same rotational speed, as the temperature increases, the injection quantity through the nozzle orifice decreases. At the same temperature, as the rotational speed increases, the injection quantity through the nozzle orifice increases. These experimental results are consistent with simulation results.

Numerical simulation of two-phase slug flow with liquid carryover in different diameter ratio T-junction

NASA Astrophysics Data System (ADS)

Pao, W.; Hon, L.; Saieed, A.; Ban, S.

2017-10-01

A smaller diameter conduit pointing at 12 o’clock position is typically hot-tapped to a horizontal laying production header in offshore platform to tap produced gas for downstream process train. This geometric feature is commonly known as T-junction. The nature of multiphase fluid splitting at the T-junction is a major operational challenge due to unpredictable production environment. Often, excessive liquid carryover occurs in the T-junction, leading to complete platform trip and halt production. This is because the downstream process train is not designed to handle excessive liquid. The objective of this research is to quantify the effect of different diameter ratio on phase separation efficiency in T-junction. The liquid carryover is modelled as two-phase air-water flow using Eulerian Mixture Model coupled with Volume of Fluid Method to mimic the slug flow in the main pipe. The focus in this paper is 0.0254 m (1 inch) diameter horizontal main arm and vertical branch arm with diameter ratio of 1.0, 0.5 and 0.3. The present research narrowed the investigation to only slug flow regime using Baker’s map as reference. The investigation found that, contrary to common believe, smaller diameter ratio T-junction perform worse than larger diameter ratio T-junction.

Numerical Heat Transfer Prediction for Laminar Flow in a Circular Pipe with a 90° Bend

NASA Astrophysics Data System (ADS)

Patro, Pandaba; Rout, Ani; Barik, Ashok

2018-06-01

Laminar air flow in a 90° bend has been studied numerically to investigate convective heat transfer, which is of practical relevance to electronic systems and refrigeration piping layout. CFD simulations are performed for Reynolds number in the range 200 to 1000 at different bend radius ratios (5, 10 and 20). The heat transfer characteristics are found to be enhanced in the curved pipe compared to a straight pipe, which are subjected to the same flow rate. The curvature and buoyancy effectively increase heat transfer in viscous laminar flows. The correlation between the flow structure and the heat transfer is found to be strong.

Generation of Turbulent Inflow Conditions for Pipe Flow via an Annular Ribbed Turbulator

NASA Astrophysics Data System (ADS)

Moallemi, Nima; Brinkerhoff, Joshua

2016-11-01

The generation of turbulent inflow conditions adds significant computational expense to direct numerical simulations (DNS) of turbulent pipe flows. Typical approaches involve introducing boxes of isotropic turbulence to the velocity field at the inlet of the pipe. In the present study, an alternative method is proposed that incurs a lower computational cost and allows the anisotropy observed in pipe turbulence to be physically captured. The method is based on a periodic DNS of a ribbed turbulator upstream of the inlet boundary of the pipe. The Reynolds number based on the bulk velocity and pipe diameter is 5300 and the blockage ratio (BR) is 0.06 based on the rib height and pipe diameter. The pitch ratio is defined as the ratio of rib streamwise spacing to rib height and is varied between 1.7 and 5.0. The generation of turbulent flow structures downstream of the ribbed turbulator are identified and discussed. Suitability of this method for accurate representation of turbulent inflow conditions is assessed through comparison of the turbulent mean properties, fluctuations, Reynolds stress profiles, and spectra with published pipe flow DNS studies. The DNS results achieve excellent agreement with the numerical and experimental data available in the literature.

Experimental research on crack detection in pipes based on Fiber Bragg grating

NASA Astrophysics Data System (ADS)

Cai, Lin; Wei, Qin; Yu, Zhaoxiang; Lu, Ming; Li, Xiaowei

2017-11-01

Crack is one of the primary faults in pipes, and its detection is a significant measure to ensure the safety of pipes. The feasibility of circumferential crack detection in pipes on the basis of fiber Bragg grating (FBG) detection technology is discussed through experimental research. Crack is formed on the surface of a metal pipe, the circumferential length of crack is one index of the damage degree. In the experiments, both electronic vibration sensor and FBG strain sensors are used to collect response signals of impulse excitation in different damage degrees. Furthermore, the characteristics of damage detection are analysed in both frequency domain and time domain. First, the natural frequencies are compared between practical and simulated results in different damage degrees of pipes; second, the multi-fractal detrended fluctuation analysis (MFDFA) is applied to acquire the singular values α as the characteristic parameter. The experimental results indicate that FBG strain sensors can perceive the impulse response of the pipe and change in different damage degrees effectively, like the vibration sensor. And both the natural frequency and the singular value are sensitive to increasing length of crack, they are able to distinguish different degrees of crack on the pipe.

A Jurassic Shock-Aftershock Earthquake Sequence Recorded by Small Clastic Pipes and Dikes within Dune Cross-Strata, Zion National Park, Utah

NASA Astrophysics Data System (ADS)

Loope, D. B.; Zlotnik, V. A.; Kettler, R. M.; Pederson, D. T.

2012-12-01

Eolian sandstones of south-central and southeast Utah contain large volumes of contorted cross-strata that have long been recognized as products of liquefaction caused by seismic shaking. Unlike most sites where Navajo Sandstone is exposed, in Zion National Park (southwestern Utah), the Navajo contains very, very few contorted strata. We have, however, mapped the distribution of more than 1,000 small-scale, vertical pipes and dikes in uncontorted cross-strata of the Navajo at two small study sites in Zion. Pipes are 2-5 cm in diameter and up to 3 m long; dikes are ~6 cm wide. Clusters of the water-escape structures lie directly above and below numerous, near-horizontal bounding surfaces. Dikes are restricted to the wind-ripple strata that lie above the bounding surfaces. Pipes are common both above and below the bounding surfaces. In map view, most pipes are arranged in lines. Near the bounding surfaces, pipes merge upward with shallow dikes trending parallel to the lines of pipes. Pipes formed in grainflows—homogeneous, well-sorted sand lacking cohesion. Dikes formed above the bounding surface, in more-cohesive, poorly sorted, wind-ripple strata. As liquefaction began, expansion of subsurface sand caused spreading within the unliquified (capping) beds near the land surface. Dikes intruded cracks in the wind-ripple strata, and pipes rose from the better-sorted sand to interdune surfaces, following trends of cracks. Because the wind-ripple strata had low cohesive strength, a depression formed around each rupture, and ejected sand built upward to a flat-topped surface rather than forming the cone of a classic sand volcano. In one 3 m2 portion of the map area, a cluster of about 20 pipes and dikes, many with truncated tops, record eight stratigraphically distinct seismic events. The large dunes that deposited the Navajo cross-strata likely moved ~1m/yr. When, in response to seismic shaking, a few liters of fluidized sand erupted onto the lowermost portion of the dune lee slope through a pipe, the erupted sand dried and was buried by climbing wind-ripple strata as the large dune continued to advance downwind. The mapped cluster recording eight distinct seismic events lies within thin-laminated sediment that was deposited by wind ripples during 1 m (~ 1 year) of southeastward dune migration. We conclude that the small pipes and dikes of our study sites are products of numerous >MM 5 earthquakes, some of which recurred at intervals of less than 2 months. We interpret one small cluster of pipes and dikes with well-defined upward terminations as a distinct shock-aftershock sequence. Because the largest modern earthquakes can produce surface liquefaction only up to about 175 km from their epicenters, the Jurassic epicenters must have been well within that distance. The tendency of modern plate boundaries to produce high-frequency aftershocks suggests that the epicenter for this Jurassic sequence lay to the southwest, within the plate boundary zone (not within continental rocks to the east). As eolian dunes steadily migrate over interdune surfaces underlain by water-saturated dune cross-strata, the thin, distinct laminae produced by the wind ripples that occupy dune toes can faithfully record high-frequency seismic events.

Modeling benzene permeation through drinking water high density polyethylene (HDPE) pipes.

PubMed

Mao, Feng; Ong, Say Kee; Gaunt, James A

2015-09-01

Organic compounds such as benzene, toluene, ethyl benzene and o-, m-, and p-xylene from contaminated soil and groundwater may permeate through thermoplastic pipes which are used for the conveyance of drinking water in water distribution systems. In this study, permeation parameters of benzene in 25 mm (1 inch) standard inside dimension ratio (SIDR) 9 high density polyethylene (HDPE) pipes were estimated by fitting the measured data to a permeation model based on a combination of equilibrium partitioning and Fick's diffusion. For bulk concentrations between 6.0 and 67.5 mg/L in soil pore water, the concentration-dependent diffusion coefficients of benzene were found to range from 2.0×10(-9) to 2.8×10(-9) cm2/s while the solubility coefficient was determined to be 23.7. The simulated permeation curves of benzene for SIDR 9 and SIDR 7 series of HDPE pipes indicated that small diameter pipes were more vulnerable to permeation of benzene than large diameter pipes, and the breakthrough of benzene into the HDPE pipe was retarded and the corresponding permeation flux decreased with an increase of the pipe thickness. HDPE pipes exposed to an instantaneous plume exhibited distinguishable permeation characteristics from those exposed to a continuous source with a constant input. The properties of aquifer such as dispersion coefficients (DL) also influenced the permeation behavior of benzene through HDPE pipes.

Failure Behavior of Elbows with Local Wall Thinning

NASA Astrophysics Data System (ADS)

Lee, Sung-Ho; Lee, Jeong-Keun; Park, Jai-Hak

Wall thinning defect due to corrosion is one of major aging phenomena in carbon steel pipes in most plant industries, and it results in reducing load carrying capacity of the piping components. A failure test system was set up for real scale elbows containing various simulated wall thinning defects, and monotonic in-plane bending tests were performed under internal pressure to find out the failure behavior of them. The failure behavior of wall-thinned elbows was characterized by the circumferential angle of thinned region and the loading conditions to the piping system.

Study on finned pipe performance as a ground heat exchanger

NASA Astrophysics Data System (ADS)

Lin, Qinglong; Ma, Jinghui; Shi, Lei

2017-08-01

The GHEs (ground heat exchangers) is an important element that determines the thermal efficiency of the entire ground-source heat-pump system. The aim of the present study is to clarify thermal performance of a new type GHE pipe, which consists straight fins of uniform cross sectional area. In this paper, GHE model is introduced and an analytical model of new type GHE pipe is developed. The heat exchange rate of BHEs utilizing finned pips is 40.42 W/m, which is 16.3% higher than normal BHEs, based on simulation analyses.

Percolation connectivity, pore size, and gas apparent permeability: Network simulations and comparison to experimental data

NASA Astrophysics Data System (ADS)

Li, M.; Tang, Y. B.; Bernabé, Y.; Zhao, J. Z.; Li, X. F.; Li, T.

2017-07-01

We modeled single-phase gas flow through porous media using percolation networks. Gas permeability is different from liquid permeability. The latter is only related to the geometry and topology of the pore space, while the former depends on the specific gas considered and varies with gas pressure. As gas pressure decreases, four flow regimes can be distinguished as viscous flow, slip flow, transition flow, and free molecular diffusion. Here we use a published conductance model presumably capable of predicting the flow rate of an arbitrary gas through a cylindrical pipe in the four regimes. We incorporated this model into pipe network simulations. We considered 3-D simple cubic, body-centered cubic, and face-centered cubic lattices, in which we varied the pipe radius distribution and the bond coordination number. Gas flow was simulated at different gas pressures. The simulation results showed that the gas apparent permeability kapp obeys an identical scaling law in all three lattices, kapp (z-zc)β, where the exponent β depends on the width of the pipe radius distribution, z is the mean coordination number, and zc its critical value at the percolation threshold. Surprisingly, (z-zc) had a very weak effect on the ratio of the apparent gas permeability to the absolute liquid permeability, kapp/kabs, suggesting that the Klinkenberg gas slippage correction factor is nearly independent of connectivity. We constructed models of kapp and kapp/kabs based on the observed power law and tested them by comparison with published experimental data on glass beads and other materials.

INTERNAL REPAIR OF PIPELINES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bill Bruce; Nancy Porter; George Ritter

2005-07-20

The two broad categories of fiber-reinforced composite liner repair and deposited weld metal repair technologies were reviewed and evaluated for potential application for internal repair of gas transmission pipelines. Both are used to some extent for other applications and could be further developed for internal, local, structural repair of gas transmission pipelines. Principal conclusions from a survey of natural gas transmission industry pipeline operators can be summarized in terms of the following performance requirements for internal repair: (1) Use of internal repair is most attractive for river crossings, under other bodies of water, in difficult soil conditions, under highways, undermore » congested intersections, and under railway crossings. (2) Internal pipe repair offers a strong potential advantage to the high cost of horizontal direct drilling when a new bore must be created to solve a leak or other problem. (3) Typical travel distances can be divided into three distinct groups: up to 305 m (1,000 ft.); between 305 m and 610 m (1,000 ft. and 2,000 ft.); and beyond 914 m (3,000 ft.). All three groups require pig-based systems. A despooled umbilical system would suffice for the first two groups which represents 81% of survey respondents. The third group would require an onboard self-contained power unit for propulsion and welding/liner repair energy needs. (4) The most common size range for 80% to 90% of operators surveyed is 508 mm (20 in.) to 762 mm (30 in.), with 95% using 558.8 mm (22 in.) pipe. Evaluation trials were conducted on pipe sections with simulated corrosion damage repaired with glass fiber-reinforced composite liners, carbon fiber-reinforced composite liners, and weld deposition. Additional un-repaired pipe sections were evaluated in the virgin condition and with simulated damage. Hydrostatic failure pressures for pipe sections repaired with glass fiber-reinforced composite liner were only marginally greater than that of pipe sections without liners, indicating that this type of liner is only marginally effective at restoring the pressure containing capabilities of pipelines. Failure pressures for larger diameter pipe repaired with a semi-circular patch of carbon fiber-reinforced composite lines were also marginally greater than that of a pipe section with un-repaired simulated damage without a liner. These results indicate that fiber reinforced composite liners have the potential to increase the burst pressure of pipe sections with external damage Carbon fiber based liners are viewed as more promising than glass fiber based liners because of the potential for more closely matching the mechanical properties of steel. Pipe repaired with weld deposition failed at pressures lower than that of un-repaired pipe in both the virgin and damaged conditions, indicating that this repair technology is less effective at restoring the pressure containing capability of pipe than a carbon fiber-reinforced liner repair. Physical testing indicates that carbon fiber-reinforced liner repair is the most promising technology evaluated to-date. In lieu of a field installation on an abandoned pipeline, a preliminary nondestructive testing protocol is being developed to determine the success or failure of the fiber-reinforced liner pipeline repairs. Optimization and validation activities for carbon-fiber repair methods are ongoing.« less

INTERNAL REPAIR OF PIPELINES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robin Gordon; Bill Bruce; Ian Harris

2004-12-31

The two broad categories of fiber-reinforced composite liner repair and deposited weld metal repair technologies were reviewed and evaluated for potential application for internal repair of gas transmission pipelines. Both are used to some extent for other applications and could be further developed for internal, local, structural repair of gas transmission pipelines. Principal conclusions from a survey of natural gas transmission industry pipeline operators can be summarized in terms of the following performance requirements for internal repair: (1) Use of internal repair is most attractive for river crossings, under other bodies of water, in difficult soil conditions, under highways, undermore » congested intersections, and under railway crossings. (2) Internal pipe repair offers a strong potential advantage to the high cost of horizontal direct drilling when a new bore must be created to solve a leak or other problem. (3) Typical travel distances can be divided into three distinct groups: up to 305 m (1,000 ft.); between 305 m and 610 m (1,000 ft. and 2,000 ft.); and beyond 914 m (3,000 ft.). All three groups require pig-based systems. A despooled umbilical system would suffice for the first two groups which represents 81% of survey respondents. The third group would require an onboard self-contained power unit for propulsion and welding/liner repair energy needs. (4) The most common size range for 80% to 90% of operators surveyed is 508 mm (20 in.) to 762 mm (30 in.), with 95% using 558.8 mm (22 in.) pipe. Evaluation trials were conducted on pipe sections with simulated corrosion damage repaired with glass fiber-reinforced composite liners, carbon fiber-reinforced composite liners, and weld deposition. Additional un-repaired pipe sections were evaluated in the virgin condition and with simulated damage. Hydrostatic failure pressures for pipe sections repaired with glass fiber-reinforced composite liner were only marginally greater than that of pipe sections without liners, indicating that this type of liner is only marginally effective at restoring the pressure containing capabilities of pipelines. Failure pressures for larger diameter pipe repaired with a semi-circular patch of carbon fiber-reinforced composite lines were also marginally greater than that of a pipe section with un-repaired simulated damage without a liner. These results indicate that fiber reinforced composite liners have the potential to increase the burst pressure of pipe sections with external damage Carbon fiber based liners are viewed as more promising than glass fiber based liners because of the potential for more closely matching the mechanical properties of steel. Pipe repaired with weld deposition failed at pressures lower than that of un-repaired pipe in both the virgin and damaged conditions, indicating that this repair technology is less effective at restoring the pressure containing capability of pipe than a carbon fiber-reinforced liner repair. Physical testing indicates that carbon fiber-reinforced liner repair is the most promising technology evaluated to-date. The first round of optimization and validation activities for carbon-fiber repairs are complete. Development of a comprehensive test plan for this process is recommended for use in the field trial portion of this program.« less

INTERNAL REPAIR OF PIPELINES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robin Gordon; Bill Bruce; Ian Harris

2004-08-17

The two broad categories of fiber-reinforced composite liner repair and deposited weld metal repair technologies were reviewed and evaluated for potential application for internal repair of gas transmission pipelines. Both are used to some extent for other applications and could be further developed for internal, local, structural repair of gas transmission pipelines. Principal conclusions from a survey of natural gas transmission industry pipeline operators can be summarized in terms of the following performance requirements for internal repair: (1) Use of internal repair is most attractive for river crossings, under other bodies of water, in difficult soil conditions, under highways, undermore » congested intersections, and under railway. (2) Internal pipe repair offers a strong potential advantage to the high cost of horizontal direct drilling when a new bore must be created to solve a leak or other problem. (3) Typical travel distances can be divided into three distinct groups: up to 305 m (1,000 ft.); between 305 m and 610 m (1,000 ft. and 2,000 ft.); and beyond 914 m (3,000 ft.). All three groups require pig-based systems. A despooled umbilical system would suffice for the first two groups which represents 81% of survey respondents. The third group would require an onboard self-contained power unit for propulsion and welding/liner repair energy needs. (4) The most common size range for 80% to 90% of operators surveyed is 508 mm (20 in.) to 762 mm (30 in.), with 95% using 558.8 mm (22 in.) pipe. Evaluation trials were conducted on pipe sections with simulated corrosion damage repaired with glass fiber-reinforced composite liners, carbon fiber-reinforced composite liners, and weld deposition. Additional un-repaired pipe sections were evaluated in the virgin condition and with simulated damage. Hydrostatic failure pressures for pipe sections repaired with glass fiber-reinforced composite liner were only marginally greater than that of pipe sections without liners, indicating that this type of liner is only marginally effective at restoring the pressure containing capabilities of pipelines. Failure pressures for larger diameter pipe repaired with a semi-circular patch of carbon fiber-reinforced composite lines were also marginally greater than that of a pipe section with un-repaired simulated damage without a liner. These results indicate that fiber reinforced composite liners have the potential to increase the burst pressure of pipe sections with external damage Carbon fiber based liners are viewed as more promising than glass fiber based liners because of the potential for more closely matching the mechanical properties of steel. Pipe repaired with weld deposition failed at pressures lower than that of un-repaired pipe in both the virgin and damaged conditions, indicating that this repair technology is less effective at restoring the pressure containing capability of pipe than a carbon fiber-reinforced liner repair. Physical testing indicates that carbon fiber-reinforced liner repair is the most promising technology evaluated to-date. Development of a comprehensive test plan for this process is recommended for use in the field trial portion of this program.« less

Chlorine Decay and DBP formation under Different Flow Regions in PVC and Ductile Iron Pipes: Preliminary Results on the Role of flow Velocity and Radial Mass Transfer - Paper

EPA Science Inventory

A systematic experimental study was conducted using a pilot-scale drinking water distribution system simulator to quantify the effect of hydrodynamics, total organic carbon (TOC), initial disinfectant levels, and pipe materials on chlorine decay and disinfection by-product (DBP) ...

Chlorine decay and DBP formation under different flow regions in PVC and ductile iron pipes: Preliminary results on the role of flow velocity and radial mass transfer

EPA Science Inventory

A systematic experimental study was conducted using a pilot-scale drinking water distribution system simulator to quantify the effect of hydrodynamics, total organic carbon (TOC), initial disinfectant levels, and pipe materials on chlorine decay and disinfection by-product (DBP) ...

An Experimental Study of Contaminant Intrusion Through Pipe Cracks

EPA Science Inventory

This report describes a series of experiments conducted at U.S. EPA’s Test and Evaluation Facility in 2013-2014 to study the intrusion of contaminated soil water into a pipe crack during simulated backflow events. A test rig was used consisting of a 3’ x 3’ x 3’ acrylic soil bo...

Retrospective cost adaptive Reynolds-averaged Navier-Stokes k-ω model for data-driven unsteady turbulent simulations

NASA Astrophysics Data System (ADS)

Li, Zhiyong; Hoagg, Jesse B.; Martin, Alexandre; Bailey, Sean C. C.

2018-03-01

This paper presents a data-driven computational model for simulating unsteady turbulent flows, where sparse measurement data is available. The model uses the retrospective cost adaptation (RCA) algorithm to automatically adjust the closure coefficients of the Reynolds-averaged Navier-Stokes (RANS) k- ω turbulence equations to improve agreement between the simulated flow and the measurements. The RCA-RANS k- ω model is verified for steady flow using a pipe-flow test case and for unsteady flow using a surface-mounted-cube test case. Measurements used for adaptation of the verification cases are obtained from baseline simulations with known closure coefficients. These verification test cases demonstrate that the RCA-RANS k- ω model can successfully adapt the closure coefficients to improve agreement between the simulated flow field and a set of sparse flow-field measurements. Furthermore, the RCA-RANS k- ω model improves agreement between the simulated flow and the baseline flow at locations at which measurements do not exist. The RCA-RANS k- ω model is also validated with experimental data from 2 test cases: steady pipe flow, and unsteady flow past a square cylinder. In both test cases, the adaptation improves agreement with experimental data in comparison to the results from a non-adaptive RANS k- ω model that uses the standard values of the k- ω closure coefficients. For the steady pipe flow, adaptation is driven by mean stream-wise velocity measurements at 24 locations along the pipe radius. The RCA-RANS k- ω model reduces the average velocity error at these locations by over 35%. For the unsteady flow over a square cylinder, adaptation is driven by time-varying surface pressure measurements at 2 locations on the square cylinder. The RCA-RANS k- ω model reduces the average surface-pressure error at these locations by 88.8%.

Water Leak Detection by Using Ground Penetrating Radar, Synthetic Simulation and Four-Dimensional Visualization

NASA Astrophysics Data System (ADS)

Al-Shukri, H.; Eyuboglu, S.; Mahdi, H.

2005-12-01

Many geophysical techniques have been suggested as candidates for detecting water leakage in water distribution system, including ground penetrating radar (GPR), acoustic devices, and gas sampling devices. A series of laboratory experiments were conducted to determine the validity and effectiveness of GPR in detecting water leakage in metal and plastic PVC pipes. The goal was to derive a practical and robust procedure for detecting such leakage. Initially, prototype laboratory experiments were designed to simulate leaks in both PVC and metal pipe. The experiments were very well controlled and results obtained indicate that GPR is effective in detecting subsurface water leaks. This was followed by an outdoor life size experiments. 50 feet by 30 feet by 5 feet test bed was constructed using local soil and commercial water distribution pipes. A 400 MHz antenna was used to collect three-dimensional GPR data as a function of time for a number of experiments using different type of pipes. Advanced imaging and visualization technology was used to further analyze the data. The UALR Virtual Reality Center CAVE facilities were utilized to accomplish this test. Results obtained indicate that GPR is effective in detecting subsurface water leaks in both pipes. Synthetic models of the GPR signals based on Finite Difference Time Domain Method (FDTD) were built to help select an appropriate equipment configuration (frequency band, type of antenna, and real-time imaging software) prior to data acquisition. The simulation software was used to determine the near-field radiation characteristics of the GPR antenna. Different experimental models were adapted for which observational GPR data was previously collected. Matlab regression analysis was used to generate the incident waves for each model to ensure highly accurate and controlled experiments.

Mathematical simulation for compensation capacities area of pipeline routes in ship systems

NASA Astrophysics Data System (ADS)

Ngo, G. V.; Sakhno, K. N.

2018-05-01

In this paper, the authors considered the problem of manufacturability’s enhancement of ship systems pipeline at the designing stage. The analysis of arrangements and possibilities for compensation of deviations for pipeline routes has been carried out. The task was set to produce the “fit pipe” together with the rest of the pipes in the route. It was proposed to compensate for deviations by movement of the pipeline route during pipe installation and to calculate maximum values of these displacements in the analyzed path. Theoretical bases of deviation compensation for pipeline routes using rotations of parallel section pairs of pipes are assembled. Mathematical and graphical simulations of compensation area capacities of pipeline routes with various configurations are completed. Prerequisites have been created for creating an automated program that will allow one to determine values of the compensatory capacities area for pipeline routes and to assign quantities of necessary allowances.

Buoyant miscible displacement flow of shear-thinning fluids: Experiments and Simulations

NASA Astrophysics Data System (ADS)

Ale Etrati Khosroshahi, Seyed Ali; Frigaard, Ian

2017-11-01

We study displacement flow of two miscible fluids with density and viscosity contrast in an inclined pipe. Our focus is mainly on displacements where transverse mixing is not significant and thus a two-layer, stratified flow develops. Our experiments are carried out in a long pipe, covering a wide range of flow-rates, inclination angles and viscosity ratios. Density and viscosity contrasts are achieved by adding Glycerol and Xanthan gum to water, respectively. At each angle, flow rate and viscosity ratio are varied and density contrast is fixed. We identify and map different flow regimes, instabilities and front dynamics based on Fr , Re / Frcosβ and viscosity ratio m. The problem is also studied numerically to get a better insight into the flow structure and shear-thinning effects. Numerical simulations are completed using OpenFOAM in both pipe and channel geometries and are compared against the experiments. Schlumberger, NSERC.

Phase transition to turbulence in a pipe

NASA Astrophysics Data System (ADS)

Goldenfeld, Nigel

Leo Kadanoff taught us much about phase transitions, turbulence and collective behavior. Here I explore the transition to turbulence in a pipe, showing how a collective mode determines the universality class. Near the transition, turbulent puffs decay either directly or through splitting, with characteristic time-scales that exhibit a super-exponential dependence on Reynolds number. Direct numerical simulations reveal that a collective mode, a so-called zonal flow emerges at large scales, activated by anisotropic turbulent fluctuations, as represented by Reynolds stress. This zonal flow imposes a shear on the turbulent fluctuations that tends to suppress their anisotropy, leading to a Landau theory of predator-prey type, in the directed percolation universality class. Stochastic simulations of this model reproduce the functional form and phenomenology of pipe flow experiments. Talk based on work performed with Hong-Yan Shih and Tsung-Lin Hsieh. This work was partially supported by the National Science Foundation through Grant NSF-DMR-1044901.

Simulation of a manual electric-arc welding in a working gas pipeline. 1. Formulation of the problem

NASA Astrophysics Data System (ADS)

Baikov, V. I.; Gishkelyuk, I. A.; Rus', A. M.; Sidorovich, T. V.; Tonkonogov, B. A.

2010-11-01

Problems of mathematical simulation of the temperature stresses arising in the wall of a pipe of a cross-country gas pipeline in the process of electric-arc welding of defects in it have been considered. Mathematical models of formation of temperatures, deformations, and stresses in a gas pipe subjected to phase transformations have been developed. These models were numerically realized in the form of algorithms representing a part of an application-program package. Results of verification of the computational complex and calculation results obtained with it are presented.

A hybrid method of estimating pulsating flow parameters in the space-time domain

NASA Astrophysics Data System (ADS)

Pałczyński, Tomasz

2017-05-01

This paper presents a method for estimating pulsating flow parameters in partially open pipes, such as pipelines, internal combustion engine inlets, exhaust pipes and piston compressors. The procedure is based on the method of characteristics, and employs a combination of measurements and simulations. An experimental test rig is described, which enables pressure, temperature and mass flow rate to be measured within a defined cross section. The second part of the paper discusses the main assumptions of a simulation algorithm elaborated in the Matlab/Simulink environment. The simulation results are shown as 3D plots in the space-time domain, and compared with proposed models of phenomena relating to wave propagation, boundary conditions, acoustics and fluid mechanics. The simulation results are finally compared with acoustic phenomena, with an emphasis on the identification of resonant frequencies.

Water Network Tool for Resilience v. 1.0

DOE Office of Scientific and Technical Information (OSTI.GOV)

2015-12-09

WNTR is a python package designed to simulate and analyze resilience of water distribution networks. The software includes: - Pressure driven and demand driven hydraulic simulation - Water quality simulation to track concentration, trace, and water age - Conditional controls to simulate power outages - Models to simulate pipe breaks - A wide range of resilience metrics - Analysis and visualization tools

Osborne Reynolds pipe flow: direct numerical simulation from laminar to fully-developed turbulence

NASA Astrophysics Data System (ADS)

Adrian, R. J.; Wu, X.; Moin, P.; Baltzer, J. R.

2014-11-01

Osborne Reynolds' pipe experiment marked the onset of modern viscous flow research, yet the detailed mechanism carrying the laminar state to fully-developed turbulence has been quite elusive, despite notable progress related to dynamic edge-state theory. Here, we continue our direct numerical simulation study on this problem using a 250R long, spatially-developing pipe configuration with various Reynolds numbers, inflow disturbances, and inlet base flow states. For the inlet base flow, both fully-developed laminar profile and the uniform plug profile are considered. Inlet disturbances consist of rings of turbulence of different width and radial location. In all the six cases examined so far, energy norms show exponential growth with axial distance until transition after an initial decay near the inlet. Skin-friction overshoots the Moody's correlation in most, but not all, the cases. Another common theme is that lambda vortices amplified out of susceptible elements in the inlet disturbances trigger rapidly growing hairpin packets at random locations and times, after which infant turbulent spots appear. Mature turbulent spots in the pipe transition are actually tight concentrations of hairpin packets looking like a hairpin forest. The plug flow inlet profile requires much stronger disturbances to transition than the parabolic profile.

Study on heat pipe assisted thermoelectric power generation system from exhaust gas

NASA Astrophysics Data System (ADS)

Chi, Ri-Guang; Park, Jong-Chan; Rhi, Seok-Ho; Lee, Kye-Bock

2017-11-01

Currently, most fuel consumed by vehicles is released to the environment as thermal energy through the exhaust pipe. Environmentally friendly vehicle technology needs new methods to increase the recycling efficiency of waste exhaust thermal energy. The present study investigated how to improve the maximum power output of a TEG (Thermoelectric generator) system assisted with a heat pipe. Conventionally, the driving energy efficiency of an internal combustion engine is approximately less than 35%. TEG with Seebeck elements is a new idea for recycling waste exhaust heat energy. The TEG system can efficiently utilize low temperature waste heat, such as industrial waste heat and solar energy. In addition, the heat pipe can transfer heat from the automobile's exhaust gas to a TEG. To improve the efficiency of the thermal power generation system with a heat pipe, effects of various parameters, such as inclination angle, charged amount of the heat pipe, condenser temperature, and size of the TEM (thermoelectric element), were investigated. Experimental studies, CFD simulation, and the theoretical approach to thermoelectric modules were carried out, and the TEG system with heat pipe (15-20% charged, 20°-30° inclined configuration) showed the best performance.

Pitting failure of copper pipings for emergency fire sprinkler in ground water

NASA Astrophysics Data System (ADS)

Baek, Seung-won; Lee, Jong-kwon; Kim, Jong-jip; Kim, Kyung-ja

2015-05-01

The possibility of microbiologically influenced corrosion was investigated in the early pitted copper pipes. The pipes were installed for less than 6 months as an immergency fire sprinkler. The bacteria were cultured by sampling of corrosion by-product near pits on failed copper pipes for the aerobic as well as anaerobic bacteria. However, only aerobic bacteria was found, which were Micrococcus Luteus and Bacillus sp.. The corrosion rate of copper pipes were studied by weight loss in the groundwater and polarization method. In immersion test as well as the electrochemical polarization test in ground water, only Micrococcus Luteus could activate corrosion of copper by 20% and 15%, respectively. On the other hand, Bacillus sp. showed little effect on corrosion in the above two tests. The shape and characteristics of failed copper pipes as well as simulated copper were investigated using stereoscope, optical microscopy, scanning electron microscope and EDS. The cause of pits were discussed, related with the dissolved copper concentrations, pH, and optical density. It could be concluded that the early failure of copper pipings could be ascribed to the acceration of copper in the presence of bacteria, i.e., Micrococcus Luteus.

Variable Conductance Heat Pipes for Radioisotope Stirling Systems

NASA Technical Reports Server (NTRS)

Anderson, William G.; Tarau, Calin

2008-01-01

In a Stirling radioisotope system, heat must continually be removed from the GPHS modules, to maintain the GPHS modules and surrounding insulation at acceptable temperatures. Normally, the Stirling convertor provides this cooling. If the Stirling engine stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS, but also ending the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) was designed to allow multiple stops and restarts of the Stirling engine. A VCHP turns on with a delta T of 30 C, which is high enough to not risk standard ASRG operation but low enough to save most heater head life. This VCHP has a low mass, and low thermal losses for normal operation. In addition to the design, a proof-of-concept NaK VCHP was fabricated and tested. While NaK is normally not used in heat pipes, it has an advantage in that it is liquid at the reservoir operating temperature, while Na or K alone would freeze. The VCHP had two condensers, one simulating the heater head, and the other simulating the radiator. The experiments successfully demonstrated operation with the simulated heater head condenser off and on, while allowing the reservoir temperature to vary over 40 to 120 C, the maximum range expected. In agreement with previous NaK heat pipe tests, the evaporator delta T was roughly 70 C, due to distillation of the NaK in the evaporator.

[Development and application of a multi-species water quality model for water distribution systems with EPANET-MSX].

PubMed

Sun, Fu; Chen, Ji-ning; Zeng, Si-yu

2008-12-01

A conceptual multi-species water quality model for water distribution systems was developed on the basis of the toolkit of the EPANET-MSX software. The model divided the pipe segment into four compartments including pipe wall, biofilm, boundary layer and bulk liquid. The involved processes were substrate utilization and microbial growth, decay and inactivation of microorganisms, mass transfer of soluble components through the boundary layer, adsorption and desorption of particular components between bulk liquid and biofilm, oxidation and halogenation of organic matter by residual chlorine, and chlorine consumption by pipe wall. The fifteen simulated variables included the seven common variables both in the biofilm and in the bulk liquid, i.e. soluble organic matter, particular organic matter, ammonia nitrogen, residual chlorine, heterotrophic bacteria, autotrophic bacteria and inert solids, as well as biofilm thickness on the pipe wall. The model was validated against the data from a series of pilot experiments, and the simulation accuracy for residual chlorine and turbidity were 0.1 mg/L and 0.3 NTU respectively. A case study showed that the model could reasonably reflect the dynamic variation of residual chlorine and turbidity in the studied water distribution system, while Monte Carlo simulation, taking into account both the variability of finished water from the waterworks and the uncertainties of model parameters, could be performed to assess the violation risk of water quality in the water distribution system.

Numerical simulation of micro-crack occurring in pipe made of stainless steel

NASA Astrophysics Data System (ADS)

Wotzka, Daria

2017-10-01

Research works carried out regard to studies aiming at determination of the effect of cumulative duty operation on the development of micro-cracks in pipelines for transport of chemical substances. This paper presents results of computer simulations of a pipeline made of stainless steel. The model was investigated using the COMSOL Multiphysics environment. The object under study was divided into sub areas and then discretized according to the FEM method. The physico-chemical parameters of individual areas were defined based on measurement data. The main aim of research works was the modeling of acoustic emission wave, which is emitted in the vicinity of the tip of micro-crack as a result of its development. In order to solve the task, heterogeneity in the structure of the material, referred to damage/micro-crack, causing local stresses was assumed. The local stresses give rise to elastic waves, which propagate in the material in all directions. When the emission waves reach the boundaries of the pipe they are then transferred into acoustic waves and propagate in the surround air, until their natural attenuation. The numerical model takes into account the effect of high pressure (3.6 MPa) and negative temperature (-100°C) of the gas, transported inside the pipe. The influence of changes of these values in the range of ± 20% on the obtained results was investigated. The main contribution of the works is the multiphysical simulation model of transportation pipe made of steel, coupling structural mechanics, thermal conductivity and acoustic waves.

Analysis of flame acceleration in open or vented obstructed pipes

NASA Astrophysics Data System (ADS)

Bychkov, Vitaly; Sadek, Jad; Akkerman, V'yacheslav

2017-01-01

While flame propagation through obstacles is often associated with turbulence and/or shocks, Bychkov et al. [V. Bychkov et al., Phys. Rev. Lett. 101, 164501 (2008), 10.1103/PhysRevLett.101.164501] have revealed a shockless, conceptually laminar mechanism of extremely fast flame acceleration in semiopen obstructed pipes (one end of a pipe is closed; a flame is ignited at the closed end and propagates towards the open one). The acceleration is devoted to a powerful jet flow produced by delayed combustion in the spaces between the obstacles, with turbulence playing only a supplementary role in this process. In the present work, this formulation is extended to pipes with both ends open in order to describe the recent experiments and modeling by Yanez et al. [J. Yanez et al., arXiv:1208.6453] as well as the simulations by Middha and Hansen [P. Middha and O. R. Hansen, Process Safety Prog. 27, 192 (2008) 10.1002/prs.10242]. It is demonstrated that flames accelerate strongly in open or vented obstructed pipes and the acceleration mechanism is similar to that in semiopen ones (shockless and laminar), although acceleration is weaker in open pipes. Starting with an inviscid approximation, we subsequently incorporate hydraulic resistance (viscous forces) into the analysis for the sake of comparing its role to that of a jet flow driving acceleration. It is shown that hydraulic resistance is actually not required to drive flame acceleration. In contrast, this is a supplementary effect, which moderates acceleration. On the other hand, viscous forces are nevertheless an important effect because they are responsible for the initial delay occurring before the flame acceleration onset, which is observed in the experiments and simulations. Accounting for this effect provides good agreement between the experiments, modeling, and the present theory.

Analysis of the coherent and turbulent stresses of a numerically simulated rough wall pipe

NASA Astrophysics Data System (ADS)

Chan, L.; MacDonald, M.; Chung, D.; Hutchins, N.; Ooi, A.

2017-04-01

A turbulent rough wall flow in a pipe is simulated using direct numerical simulation (DNS) where the roughness elements consist of explicitly gridded three-dimensional sinusoids. Two groups of simulations were conducted where the roughness semi-amplitude h+ and the roughness wavelength λ+ are systematically varied. The triple decomposition is applied to the velocity to separate the coherent and turbulent components. The coherent or dispersive component arises due to the roughness and depends on the topological features of the surface. The turbulent stress on the other hand, scales with the friction Reynolds number. For the case with the largest roughness wavelength, large secondary flows are observed which are similar to that of duct flows. The occurrence of these large secondary flows is due to the spanwise heterogeneity of the roughness which has a spacing approximately equal to the boundary layer thickness δ.

Multiphase numerical analysis of heat pipe with different working fluids for solar applications

NASA Astrophysics Data System (ADS)

Aswath, S.; Netaji Naidu, V. H.; Padmanathan, P.; Raja Sekhar, Y.

2017-11-01

Energy crisis is a prognosis predicted in many cases with the indiscriminate encroachment of conventional energy sources for applications on a massive scale. This prediction, further emboldened by the marked surge in global average temperatures, attributed to climate change and global warming, the necessity to conserve the environment and explore alternate sources of energy is at an all-time high. Despite being among the lead candidates for such sources, solar energy is utilized far from its vast potential possibilities due to predominant economic constraints. Even while there is a growing need for solar panels at more affordable rates, the other options to harness better out of sun’s energy is to optimize and improvise existing technology. One such technology is the heat pipe used in Evacuated Tube Collectors (ETC). The applications of heat pipe have been gaining momentum in various fields since its inception and substantial volumes of research have explored optimizing and improving the technology which is proving effective in heat recovery and heat transfer better than conventional systems. This paper carries out a computational analysis on a comparative simulation between two working fluids within heat pipe of same geometry. It further endeavors to study the multiphase transitions within the heat pipe. The work is carried out using ANSYS Fluent with inputs taken from solar data for the location of Vellore, Tamil Nadu. A wickless, gravity-assisted heat pipe (GAHP) is taken for the simulation. Water and ammonia are used as the working fluids for comparative multiphase analysis to arrive at the difference in heat transfer at the condenser section. It is demonstrated that a heat pipe ETC with ammonia as working fluid showed higher heat exchange (temperature difference) as against that of water as working fluid. The multiphase model taken aided in study of phase transitions within both cases and supported the result of ammonia as fluid being a better candidate.

Comparison of Microbial Communities in a Simulated Chloraminated Drinking Water Distribution System Subjected to Episodes of Nitrification (poster)

EPA Science Inventory

Bacterial populations were examined in a simulated chloraminated drinking water distribution system (i.e. PVC pipe loop). After six months of continuous operation, coupons were incubated in CDC reactors receiving water from the simulated system to study biofilm development. The s...

Simulation of Targets Feeding Pipe Rupture in Wendelstein 7-X Facility Using RELAP5 and COCOSYS Codes

NASA Astrophysics Data System (ADS)

Kaliatka, T.; Povilaitis, M.; Kaliatka, A.; Urbonavicius, E.

2012-10-01

Wendelstein nuclear fusion device W7-X is a stellarator type experimental device, developed by Max Planck Institute of plasma physics. Rupture of one of the 40 mm inner diameter coolant pipes providing water for the divertor targets during the "baking" regime of the facility operation is considered to be the most severe accident in terms of the plasma vessel pressurization. "Baking" regime is the regime of the facility operation during which plasma vessel structures are heated to the temperature acceptable for the plasma ignition in the vessel. This paper presents the model of W7-X cooling system (pumps, valves, pipes, hydro-accumulators, and heat exchangers), developed using thermal-hydraulic state-of-the-art RELAP5 Mod3.3 code, and model of plasma vessel, developed by employing the lumped-parameter code COCOSYS. Using both models the numerical simulation of processes in W7-X cooling system and plasma vessel has been performed. The results of simulation showed, that the automatic valve closure time 1 s is the most acceptable (no water hammer effect occurs) and selected area of the burst disk is sufficient to prevent pressure in the plasma vessel.

Flow simulations on an organ pipe foot model.

PubMed

Vaik, István; Paál, György

2013-02-01

The present paper shows numerical simulations of the flow responsible for the sound generation in an organ pipe. Only the foot model of the organ pipe (i.e., with the resonator detached) is investigated by two-dimensional incompressible CFD simulations. It is shown that in spite of the moderately high Reynolds number (Re≈2350) no turbulence modeling is necessary. Free jet simulation (foot model without the upper lip) showed that the jet oscillates due to its natural instability. The velocity profile, the centerline and the width of the jet is determined at different heights above the flue. Edge tone simulations (foot model with the upper lip) were carried out having the upper lip at a constant height but at different x positions. It was found that the strongest and most stable edge tone oscillation occurs if the lower left corner of the upper lip is in the centerline of the jet (optimum position). When the upper lip is far from its optimum position the oscillation of the jet is rather due to the natural instability of the jet than the edge tone phenomenon. The results agree well with the experimental results of Außerlechner et al. [J. Acoust. Soc. Am. 126, 878-886 (2009)] and Außerlechner (Ph.D. thesis, Universität Stuttgart, Stuttgart, Germany) and with former results of the authors [Paál and Vaik, Int. J. Heat Fluid Flow 28, 575-586 (2007); Paál and Vaik, in Conference on Modelling Fluid Flow (CMFF'09), Budapest, Hungary].

Carrier fluid temperature data in vertical ground heat exchangers with a varying pipe separation.

PubMed

Makasis, Nikolas; Narsilio, Guillermo A; Bidarmaghz, Asal; Johnston, Ian W

2018-06-01

The dataset in this article is related to shallow geothermal energy systems, which efficiently provide renewable heating and cooling to buildings, and specifically to the performance of the vertical ground heat exchangers (GHE) embedded in the ground. GHEs incorporate pipes with a circulating (carrier) fluid, exchanging heat between the ground and the building. The data show the average and inlet temperatures of the carrier fluid circulating in the pipes embedded in the GHEs (which directly relate to the performance of these systems). These temperatures were generated using detailed finite element modelling and comprise part of the daily output of various one-year simulations, accounting for numerous design parameters (including different pipe geometries) and ground conditions. An expanded explanation of the data as well as comprehensive analyses on how they were used can be found in the article titled "Ground-source heat pump systems: the effect of variable pipe separation in ground heat exchangers" (Makasis N, Narsilio GA, Bidarmaghz A, Johnston IW, 2018) [1].

Optimum Material Composition for Minimizing the Stress Intensity Factor of Edge Crack in Thick-Walled FGM Circular Pipes Under Thermomechanical Loading

NASA Astrophysics Data System (ADS)

Sekine, Hideki; Yoshida, Kimiaki

This paper deals with the optimization problem of material composition for minimizing the stress intensity factor of radial edge crack in thick-walled functionally graded material (FGM) circular pipes under steady-state thermomechanical loading. Homogenizing the FGM circular pipes by simulating the inhomogeneity of thermal conductivity by a distribution of equivalent eigentemperature gradient and the inhomogeneity of Young's modulus and Poisson's ratio by a distribution of equivalent eigenstrain, we present an approximation method to obtain the stress intensity factor of radial edge crack in the FGM circular pipes. The optimum material composition for minimizing the stress intensity factor of radial edge crack is determined using a nonlinear mathematical programming method. Numerical results obtained for a thick-walled TiC/Al2O3 FGM circular pipe reveal that it is possible to decrease remarkably the stress intensity factor of radial edge crack by setting the optimum material composition profile.

Modeling of surface roughness effects on Stokes flow in circular pipes

NASA Astrophysics Data System (ADS)

Song, Siyuan; Yang, Xiaohu; Xin, Fengxian; Lu, Tian Jian

2018-02-01

Fluid flow and pressure drop across a channel are significantly influenced by surface roughness on a channel wall. The present study investigates the effects of periodically structured surface roughness upon flow field and pressure drop in a circular pipe at low Reynolds numbers. The periodic roughness considered exhibits sinusoidal, triangular, and rectangular morphologies, with the relative roughness (i.e., ratio of the amplitude of surface roughness to hydraulic diameter of the pipe) no more than 0.2. Based upon a revised perturbation theory, a theoretical model is developed to quantify the effect of roughness on fully developed Stokes flow in the pipe. The ratio of static flow resistivity and the ratio of the Darcy friction factor between rough and smooth pipes are expressed in four-order approximate formulations, which are validated against numerical simulation results. The relative roughness and the wave number are identified as the two key parameters affecting the static flow resistivity and the Darcy friction factor.

Non-planar vibrations of slightly curved pipes conveying fluid in simple and combination parametric resonances

NASA Astrophysics Data System (ADS)

Czerwiński, Andrzej; Łuczko, Jan

2018-01-01

The paper summarises the experimental investigations and numerical simulations of non-planar parametric vibrations of a statically deformed pipe. Underpinning the theoretical analysis is a 3D dynamic model of curved pipe. The pipe motion is governed by four non-linear partial differential equations with periodically varying coefficients. The Galerkin method was applied, the shape function being that governing the beam's natural vibrations. Experiments were conducted in the range of simple and combination parametric resonances, evidencing the possibility of in-plane and out-of-plane vibrations as well as fully non-planar vibrations in the combination resonance range. It is demonstrated that sub-harmonic and quasi-periodic vibrations are likely to be excited. The method suggested allows the spatial modes to be determined basing on results registered at selected points in the pipe. Results are summarised in the form of time histories, phase trajectory plots and spectral diagrams. Dedicated video materials give us a better insight into the investigated phenomena.

Neural-Fuzzy model Based Steel Pipeline Multiple Cracks Classification

NASA Astrophysics Data System (ADS)

Elwalwal, Hatem Mostafa; Mahzan, Shahruddin Bin Hj.; Abdalla, Ahmed N.

2017-10-01

While pipes are cheaper than other means of transportation, this cost saving comes with a major price: pipes are subject to cracks, corrosion etc., which in turn can cause leakage and environmental damage. In this paper, Neural-Fuzzy model for multiple cracks classification based on Lamb Guide Wave. Simulation results for 42 sample were collected using ANSYS software. The current research object to carry on the numerical simulation and experimental study, aiming at finding an effective way to detection and the localization of cracks and holes defects in the main body of pipeline. Considering the damage form of multiple cracks and holes which may exist in pipeline, to determine the respective position in the steel pipe. In addition, the technique used in this research a guided lamb wave based structural health monitoring method whereas piezoelectric transducers will use as exciting and receiving sensors by Pitch-Catch method. Implementation of simple learning mechanism has been developed specially for the ANN for fuzzy the system represented.

An automatic detection method for the boiler pipe header based on real-time image acquisition

NASA Astrophysics Data System (ADS)

Long, Yi; Liu, YunLong; Qin, Yongliang; Yang, XiangWei; Li, DengKe; Shen, DingJie

2017-06-01

Generally, an endoscope is used to test the inner part of the thermal power plants boiler pipe header. However, since the endoscope hose manual operation, the length and angle of the inserted probe cannot be controlled. Additionally, it has a big blind spot observation subject to the length of the endoscope wire. To solve these problems, an automatic detection method for the boiler pipe header based on real-time image acquisition and simulation comparison techniques was proposed. The magnetic crawler with permanent magnet wheel could carry the real-time image acquisition device to complete the crawling work and collect the real-time scene image. According to the obtained location by using the positioning auxiliary device, the position of the real-time detection image in a virtual 3-D model was calibrated. Through comparing of the real-time detection images and the computer simulation images, the defects or foreign matter fall into could be accurately positioning, so as to repair and clean up conveniently.

Analysis on shock wave speed of water hammer of lifting pipes for deep-sea mining

NASA Astrophysics Data System (ADS)

Zhou, Zhi-jin; Yang, Ning; Wang, Zhao

2013-04-01

Water hammer occurs whenever the fluid velocity in vertical lifting pipe systems for deep-sea mining suddenly changes. In this work, the shock wave was proven to play an important role in changing pressures and periods, and mathematical and numerical modeling technology was presented for simulated transient pressure in the abnormal pump operation. As volume concentrations were taken into account of shock wave speed, the experiment results about the pressure-time history, discharge-time history and period for the lifting pipe system showed that: as its concentrations rose up, the maximum transient pressure went down, so did its discharges; when its volume concentrations increased gradually, the period numbers of pressure decay were getting less and less, and the corresponding shock wave speed decreased. These results have highly coincided with simulation results. The conclusions are important to design lifting transporting system to prevent water hammer in order to avoid potentially devastating consequences, such as damage to components and equipment and risks to personnel.

Influence of thermo-gravitational convection in the flow of liquid metal in a horizontal pipe with a longitudinal magnetic field

NASA Astrophysics Data System (ADS)

Akhmedagaev, R.; Listratov, Y.

2017-11-01

The direct numerical simulation (DNS) of MHD-heat transfer problems in turbulent flow of liquid metal (LM) in a horizontal pipe with a joint effect of the longitudinal magnetic field (MF) and thermo-gravitational convection (TGC). The authors calculated the effect of TGC in a strong longitudinal MF for a homogeneous heating. Investigated the averaged fields of velocity and temperature, heat transfer characteristics, the distribution of wall temperature along the perimeter of the cross section of the pipe. The effect of TGC on the velocity field is affected stronger than in the temperature field.

Genetic Optimization and Simulation of a Piezoelectric Pipe-Crawling Inspection Robot

NASA Technical Reports Server (NTRS)

Hollinger, Geoffrey A.; Briscoe, Jeri M.

2004-01-01

Using the DarwinZk development software, a genetic algorithm (GA) was used to design and optimize a pipe-crawling robot for parameters such as mass, power consumption, and joint extension to further the research of the Miniature Inspection Systems Technology (MIST) team. In an attempt to improve on existing designs, a new robot was developed, the piezo robot. The final proposed design uses piezoelectric expansion actuators to move the robot with a 'chimneying' method employed by mountain climbers and greatly improves on previous designs in load bearing ability, pipe traversing specifications, and field usability. This research shows the advantages of GA assisted design in the field of robotics.

Heat pipe dynamic behavior

NASA Technical Reports Server (NTRS)

Issacci, F.; Roche, G. L.; Klein, D. B.; Catton, I.

1988-01-01

The vapor flow in a heat pipe was mathematically modeled and the equations governing the transient behavior of the core were solved numerically. The modeled vapor flow is transient, axisymmetric (or two-dimensional) compressible viscous flow in a closed chamber. The two methods of solution are described. The more promising method failed (a mixed Galerkin finite difference method) whereas a more common finite difference method was successful. Preliminary results are presented showing that multi-dimensional flows need to be treated. A model of the liquid phase of a high temperature heat pipe was developed. The model is intended to be coupled to a vapor phase model for the complete solution of the heat pipe problem. The mathematical equations are formulated consistent with physical processes while allowing a computationally efficient solution. The model simulates time dependent characteristics of concern to the liquid phase including input phase change, output heat fluxes, liquid temperatures, container temperatures, liquid velocities, and liquid pressure. Preliminary results were obtained for two heat pipe startup cases. The heat pipe studied used lithium as the working fluid and an annular wick configuration. Recommendations for implementation based on the results obtained are presented. Experimental studies were initiated using a rectangular heat pipe. Both twin beam laser holography and laser Doppler anemometry were investigated. Preliminary experiments were completed and results are reported.

Statespace geometry of puff formation in pipe flow

NASA Astrophysics Data System (ADS)

Budanur, Nazmi Burak; Hof, Bjoern

2017-11-01

Localized patches of chaotically moving fluid known as puffs play a central role in the transition to turbulence in pipe flow. Puffs coexist with the laminar flow and their large-scale dynamics sets the critical Reynolds number: When the rate of puff splitting exceeds that of decaying, turbulence in a long pipe becomes sustained in a statistical sense. Since puffs appear despite the linear stability of the Hagen-Poiseuille flow, one expects them to emerge from the bifurcations of finite-amplitude solutions of Navier-Stokes equations. In numerical simulations of pipe flow, Avila et al., discovered a pair of streamwise localized relative periodic orbits, which are time-periodic solutions with spatial drifts. We combine symmetry reduction and Poincaré section methods to compute the unstable manifolds of these orbits, revealing statespace structures associated with different stages of puff formation.

A Vibration-Based Strategy for Health Monitoring of Offshore Pipelines' Girth-Welds

PubMed Central

Razi, Pejman; Taheri, Farid

2014-01-01

This study presents numerical simulations and experimental verification of a vibration-based damage detection technique. Health monitoring of a submerged pipe's girth-weld against an advancing notch is attempted. Piezoelectric transducers are bonded on the pipe for sensing or actuation purposes. Vibration of the pipe is excited by two means: (i) an impulsive force; (ii) using one of the piezoelectric transducers as an actuator to propagate chirp waves into the pipe. The methodology adopts the empirical mode decomposition (EMD), which processes vibration data to establish energy-based damage indices. The results obtained from both the numerical and experimental studies confirm the integrity of the approach in identifying the existence, and progression of the advancing notch. The study also discusses and compares the performance of the two vibration excitation means in damage detection. PMID:25225877

Effect of inlet cone pipe angle in catalytic converter

NASA Astrophysics Data System (ADS)

Amira Zainal, Nurul; Farhain Azmi, Ezzatul; Arifin Samad, Mohd

2018-03-01

The catalytic converter shows significant consequence to improve the performance of the vehicle start from it launched into production. Nowadays, the geometric design of the catalytic converter has become critical to avoid the behavior of backpressure in the exhaust system. The backpressure essentially reduced the performance of vehicles and increased the fuel consumption gradually. Consequently, this study aims to design various models of catalytic converter and optimize the volume of fluid flow inside the catalytic converter by changing the inlet cone pipe angles. Three different geometry angles of the inlet cone pipe of the catalytic converter were assessed. The model is simulated in Solidworks software to determine the optimum geometric design of the catalytic converter. The result showed that by decreasing the divergence angle of inlet cone pipe will upsurge the performance of the catalytic converter.

HPTAM, a two-dimensional Heat Pipe Transient Analysis Model, including the startup from a frozen state

NASA Technical Reports Server (NTRS)

Tournier, Jean-Michel; El-Genk, Mohamed S.

1995-01-01

A two-dimensional Heat Pipe Transient Analysis Model, 'HPTAM,' was developed to simulate the transient operation of fully-thawed heat pipes and the startup of heat pipes from a frozen state. The model incorporates: (a) sublimation and resolidification of working fluid; (b) melting and freezing of the working fluid in the porous wick; (c) evaporation of thawed working fluid and condensation as a thin liquid film on a frozen substrate; (d) free-molecule, transition, and continuum vapor flow regimes, using the Dusty Gas Model; (e) liquid flow and heat transfer in the porous wick; and (f) thermal and hydrodynamic couplings of phases at their respective interfaces. HPTAM predicts the radius of curvature of the liquid meniscus at the liquid-vapor interface and the radial location of the working fluid level (liquid or solid) in the wick. It also includes the transverse momentum jump condition (capillary relationship of Pascal) at the liquid-vapor interface and geometrically relates the radius of curvature of the liquid meniscus to the volume fraction of vapor in the wick. The present model predicts the capillary limit and partial liquid recess (dryout) in the evaporator wick, and incorporates a liquid pooling submodel, which simulates accumulation of the excess liquid in the vapor core at the condenser end.

Modeling of the steam hydrolysis in a two-step process for hydrogen production by solar concentrated energy

NASA Astrophysics Data System (ADS)

Valle-Hernández, Julio; Romero-Paredes, Hernando; Pacheco-Reyes, Alejandro

2017-06-01

In this paper the simulation of the steam hydrolysis for hydrogen production through the decomposition of cerium oxide is presented. The thermochemical cycle for hydrogen production consists of the endothermic reduction of CeO2 to lower-valence cerium oxide, at high temperature, where concentrated solar energy is used as a source of heat; and of the subsequent steam hydrolysis of the resulting cerium oxide to produce hydrogen. The modeling of endothermic reduction step was presented at the Solar Paces 2015. This work shows the modeling of the exothermic step; the hydrolysis of the cerium oxide (III) to form H2 and the corresponding initial cerium oxide made at lower temperature inside the solar reactor. For this model, three sections of the pipe where the reaction occurs were considered; the steam water inlet, the porous medium and the hydrogen outlet produced. The mathematical model describes the fluid mechanics; mass and energy transfer occurring therein inside the tungsten pipe. Thermochemical process model was simulated in CFD. The results show a temperature distribution in the solar reaction pipe and allow obtaining the fluid dynamics and the heat transfer within the pipe. This work is part of the project "Solar Fuels and Industrial Processes" from the Mexican Center for Innovation in Solar Energy (CEMIE-Sol).

Turbulent pipe flows subjected to temporal decelerations

NASA Astrophysics Data System (ADS)

Jeong, Wongwan; Lee, Jae Hwa

2016-11-01

Direct numerical simulations of temporally decelerating turbulent pipe flows were performed to examine effects of temporal decelerations on turbulence. The simulations were started with a fully developed turbulent pipe flow at a Reynolds number, ReD =24380, based on the pipe radius (R) and the laminar centerline velocity (Uc 0). Three different temporal decelerations were imposed to the initial flow with f= | d Ub / dt | =0.00127, 0.00625 and 0.025, where Ub is the bulk mean velocity. Comparison of Reynolds stresses and turbulent production terms with those for steady flow at a similar Reynolds number showed that turbulence is highly intensified with increasing f due to delay effects. Furthermore, inspection of the Reynolds shear stress profiles showed that strong second- and fourth-quadrant Reynolds shear stresses are greatly increased, while first- and third-quadrant components are also increased. Decomposition of streamwise Reynolds normal stress with streamwise cutoff wavelength (λx) 1 R revealed that the turbulence delay is dominantly originated from delay of strong large-scale turbulent structures in the outer layer, although small-scale motions throughout the wall layer adjusted more rapidly to the temporal decelerations. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2014R1A1A2057031).

Mass Median Plume Angle: A novel approach to characterize plume geometry in solution based pMDIs.

PubMed

Moraga-Espinoza, Daniel; Eshaghian, Eli; Smyth, Hugh D C

2018-05-30

High-speed laser imaging (HSLI) is the preferred technique to characterize the geometry of the plume in pressurized metered dose inhalers (pMDIs). However, current methods do not allow for simulation of inhalation airflow and do not use drug mass quantification to determine plume angles. To address these limitations, a Plume Induction Port Evaluator (PIPE) was designed to characterize the plume geometry based on mass deposition patterns. The method is easily adaptable to current pMDI characterization methodologies, uses similar calculations methods, and can be used under airflow. The effect of airflow and formulation on the plume geometry were evaluated using PIPE and HSLI. Deposition patterns in PIPE were highly reproducible and log-normal distributed. Mass Median Plume Angle (MMPA) was a new characterization parameter to describe the effective angle of the droplets deposited in the induction port. Plume angles determined by mass showed a significant decrease in size as ethanol increases which correlates to the decrease on vapor pressure in the formulation. Additionally, airflow significantly decreased the angle of the plumes when cascade impactor was operated under flow. PIPE is an alternative to laser-based characterization methods to evaluate the plume angle of pMDIs based on reliable drug quantification while simulating patient inhalation. Copyright © 2018. Published by Elsevier B.V.

Variable Conductance Heat Pipes for Radioisotope Stirling Systems

NASA Astrophysics Data System (ADS)

Anderson, William G.; Tarau, Calin

2008-01-01

In a Stirling radioisotope system, heat must continually be removed from the GPHS modules, to maintain the GPHS modules and surrounding insulation at acceptable temperatures. Normally, the Stirling convertor provides this cooling. If the Stirling engine stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS, but also ending the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) was designed to allow multiple stops and restarts of the Stirling engine. A VCHP was designed for the Advanced Stirling Radioisotope Generator, with a 850 °C heater head temperature. The VCHP turns on with a ΔT of 30 °C, which is high enough to not risk standard ASRG operation but low enough to save most heater head life. This VCHP has a low mass, and low thermal losses for normal operation. In addition to the design, a proof-of-concept NaK VCHP was fabricated and tested. While NaK is normally not used in heat pipes, it has an advantage in that it is liquid at the reservoir operating temperature, while Na or K alone would freeze. The VCHP had two condensers, one simulating the heater head, and the other simulating the radiator. The experiments successfully demonstrated operation with the simulated heater head condenser off and on, while allowing the reservoir temperature to vary over 40 to 120 °C, the maximum range expected. In agreement with previous NaK heat pipe tests, the evaporator ΔT was roughly 70 °C, due to distillation of the NaK in the evaporator.

Simulation of external contamination into water distribution systems through defects in pipes

NASA Astrophysics Data System (ADS)

López, P. A.; Mora, J. J.; García, F. J.; López, G.

2009-04-01

Water quality can be defined as a set of properties (physical, biological and chemical) that determine its suitability for human use or for its role in the biosphere. In this contribution we focus on the possible impact on water distribution systems quality of external contaminant fluids entering through defects in pipes. The physical integrity of the distribution system is a primary barrier against the entry of external contaminants and the loss in quality of the treated drinking water, but this integrity can be broken. Deficiencies in physical and hydraulic integrity can lead into water losses, but also into the influx of contaminants through pipes walls, either through breaks coming from external subsoil waters, or via cross connections coming from sewerage or other facilities. These external contamination events (the so called pathogen intrusion phenomenon) can act as a source of income by introducing nutrients and sediments as well as decreasing disinfectant concentrations within the distribution system, thus resulting in a degradation of the distribution water quality. The objective of this contribution is to represent this pathogen intrusion phenomenon. The combination of presence of defects in the infrastructures (equipment failure), suppression and back-siphonage and lack of disinfection is the cause of propagation of contamination in the clean current of water. Intrusion of pathogenic microorganisms has been studied and registered even in well maintained services. Therefore, this situation can happen when negative pressure conditions are achieved in the systems combined with the presence of defects in pipes nearby the suppression. A simulation of the process by which the external fluids can come inside pipes across their defects in a steady-state situation will be considered, by using different techniques to get such a successful modeling, combining numerical and experimental simulations. The proposed modeling process is based on experimental and computational simulations. An analysis of the intrusion behavior considering hydrodynamic and transportation of pollutant phenomena has been developed, comparing the influence of the turbulence consideration and the agreement of both computational and experimental results. This paper is focused on the analysis of such external intrusion phenomenon, the relationship between the income flow and the pressure inside the pipe, depending on the characteristics of the defect and the pressure level, as well as the effect on the water quality of the income substances dispersion. Two different experiments have been developed. In order to represent the intrusion phenomenon in steady state, two suitable assemblies have been implemented in the laboratory. In a lower order of pressures a Venturi tube has been used for generating the depression. In a higher level of pressures, a pumping system has been used. The defect on the pipe has been simulated by a circular hole, and the dispersion of pollutant has been considered by means of salinity as a conservative contaminant. The simulated scenarios of different suppressions can vary from 0.001 to 0.7 bars. The prototypes are also simulated by numerical modeling in two and three dimensions using Computational Fluid Dynamics techniques. For this purpose Fluent 6.3™ has been used, which displays the fields of hydrodynamic components and salinity. After doing a proper calibration process, the contrast made between models will allows us to establish the foundation for further pathogen intrusion simulations in the distribution system. Different turbulent models based on turbulent viscosity and different boundary conditions will also be considered. The agreement between experimental and computational models will be analyzed, and the differences between series of results will be compared, validating thus the use of computational models for representing the pathogen intrusion problem. By both, mathematical and physical models, it is intended to have a better knowledge of quantities that can not be measured, such as velocity fields, aspects of turbulence, pressure fields, concentrations, etc. existing in mixing processes related to external intrusion.

Epidemiology of urban water distribution systems

NASA Astrophysics Data System (ADS)

Bardet, Jean-Pierre; Little, Richard

2014-08-01

Urban water distribution systems worldwide contain numerous old and fragile pipes that inevitably break, flood streets and damage property, and disrupt economic and social activities. Such breaks often present dramatically in temporal clusters as occurred in Los Angeles during 2009. These clustered pipe breaks share many characteristics with human mortality observed during extreme climatological events such as heat waves or air pollution. Drawing from research and empirical studies in human epidemiology, a framework is introduced to analyze the time variations of disruptive pipe breaks that can help water agencies better understand clustered pipe failures and institute measures to minimize the disruptions caused by them. It is posited that at any time, a cohort of the pipes comprising the water distribution system will be in a weakened state due to fatigue and corrosion. This frail cohort becomes vulnerable during normal operations and ultimately breaks due to rapid increase in crack lengths induced by abnormal stressors. The epidemiological harvesting model developed in this paper simulates an observed time series of monthly pipe breaks and has both explanatory and predictive power. It also demonstrates that models from nonengineering disciplines such as medicine can provide improved insights into the performance of infrastructure systems.

Numerical analysis of the heat transfer and fluid flow in the butt-fusion welding process

NASA Astrophysics Data System (ADS)

Yoo, Jae Hyun; Choi, Sunwoong; Nam, Jaewook; Ahn, Kyung Hyun; Oh, Ju Seok

2017-02-01

Butt-fusion welding is an effective process for welding polymeric pipes. The process can be simplified into two stages. In heat soak stage, the pipe is heated using a hot plate contacted with one end of the pipe. In jointing stage, a pair of heated pipes is compressed against one another so that the melt regions become welded. In previous works, the jointing stage that is highly related to the welding quality was neglected. However, in this study, a finite element simulation is conducted including the jointing stage. The heat and momentum transfer are considered altogether. A new numerical scheme to describe the melt flow and pipe deformation for the butt-fusion welding process is introduced. High density polyethylene (HDPE) is used for the material. Flow via thermal expansion of the heat soak stage, and squeezing and fountain flow of the jointing stage are well reproduced. It is also observed that curling beads are formed and encounter the pipe body. The unique contribution of this study is its capability of directly observing the flow behaviors that occur during the jointing stage and relating them to welding quality.

Tilt angle dependence of backscattering enhancements from organ pipe modes of open water-filled cylinders: Measurements and models

NASA Astrophysics Data System (ADS)

Osterhoudt, Curtis F.; Marston, Philip L.

2003-04-01

A simple target for simulating narrow low-frequency resonances of cylinders is an open metal pipe completely filled with water. We have previously described how the high-Q organ-pipe modes having a pressure node near each end are easily observed in backscattering experiments with small cylinders [C. F. Osterhoudt and P. L. Marston, J. Acoust. Soc. Am. 110, 2773 (2001)]. The resonance occurs because of the strong reflection of internal acoustic waves from the open ends of the pipe [H. Levine and J. Schwinger, Phys. Rev. 73, 383-406 (1948)]. In the present research, the dependence of the backscattering amplitude on the orientation of the cylinder is measured and modeled. The tilt angle dependence is affected by the symmetry of the organ pipe mode. An approximation was also developed for the backscattering amplitude at high Q resonances based on energy conservation, reciprocity, and the optical theorem. While this analysis applies to cylinders suspended in water away from boundaries, the organ-pipe modes studied may be useful for investigating scattering processes for buried or partially buried cylinders. [Research supported in part by ONR.

Use of clinical simulations for patient education: targeting an untapped audience.

PubMed

Siwe, Karin; Berterö, Carina; Pugh, Carla; Wijma, Barbro

2009-01-01

In most cases, the health professional has been the target for simulation based learning curricula. We have developed a simulation based curriculum for patient education. In our curriculum lay-women learn how to perform the clinical female pelvic examination using a manikin-based trainer. Learner assessments show that prior negative expectations turned into positive expectations regarding future pelvic examinations.

Simulation and Technology of Hybrid Welding of Thick Steel Parts with High Power Fiber Laser

NASA Astrophysics Data System (ADS)

Turichin, Gleb; Valdaytseva, Ekaterina; Tzibulsky, Igor; Lopota, Alexander; Velichko, Olga

The article devoted to steady state and dynamic simulation of melt pool behavior during hybrid laser-arc welding of pipes and shipbuilding sections. The quasi-stationary process-model was used to determine an appropriate welding mode. The dynamical model of laser welding was used for investigation of keyhole depth and width oscillations. The experiments of pipe steel and stainless steel hybrid laser-MAG welding have been made with 15-kW fiber laser in wide range of welding mode parameters. Comparison of experimentally measured and simulated behavior of penetration depth as well as their oscillation spectra approved the self-oscillation nature of melt pool behavior. The welding mode influence of melt pool stability has also been observed. The technological peculiarities, which allow provide high quality weld seam, has been discussed also.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kot, C.A.; Srinivasan, M.G.; Hsieh, B.J.

As part of the Phase II testing at the HDR Test Facility in Kahl/Main, FRG, two series of high-level seismic/vibrational experiments were performed. In the first of these (SHAG) a coast-down shaker, mounted on the reactor operating floor and capable of generating 1000 tonnes of force, was used to investigate full-scale structural response, soil-structure interaction (SSI), and piping/equipment response at load levels equivalent to those of a design basis earthquake. The HDR soil/structure system was tested to incipient failure exhibiting highly nonlinear response. In the load transmission from structure to piping/equipment significant response amplifications and shifts to higher frequencies occurred.more » The performance of various pipe support configurations was evaluated. This latter effort was continued in the second series of tests (SHAM), in which an in-plant piping system was investigated at simulated seismic loads (generated by two servo-hydraulic actuators each capable of generating 40 tonnes of force), that exceeded design levels manifold and resulted in considerable pipe plastification and failure of some supports (snubbers). The evaluation of six different support configurations demonstrated that proper system design (for a given spectrum) rather than number of supports or system stiffness is essential to limiting pipe stresses. Pipe strains at loads exceeding the design level eightfold were still tolerable, indicating that pipe failure even under extreme seismic loads is unlikely inspite of multiple support failures. Conservatively, an excess capacity (margin) of at least four was estimated for the piping system, and the pipe damping was found to be 4%. Comparisons of linear and nonlinear computational results with measurements showed that analytical predictions have wide scatter and do not necessarily yield conservative responses, underpredicting, in particular, peak support forces.« less

Towards CFD modeling of turbulent pipeline material transportation

NASA Astrophysics Data System (ADS)

Shahirpour, Amir; Herzog, Nicoleta; Egbers, Cristoph

2013-04-01

Safe and financially efficient pipeline transportation of carbon dioxide is a critical issue in the developing field of the CCS Technology. In this part of the process, carbon dioxide is transported via pipes with diameter of 1.5 m and entry pressure of 150 bar, with Reynolds number of 107 and viscosity of 8×10(-5) Pa.s as dense fluid [1]. Presence of large and small scale structures in the pipeline, high Reynolds numbers at which CO2 should be transferred, and 3 dimensional turbulence caused by local geometrical modifications, increase the importance of simulation of turbulent material transport through the individual components of the CO2 chain process. In this study, incompressible turbulent channel flow and pipe flow have been modeled using OpenFoam, an open source CFD software. In the first step, simulation of a turbulent channel flow has been considered using LES for shear Reynolds number of 395. A simple geometry has been chosen with cyclic fluid inlet and outlet boundary conditions to simulate a fully developed flow. The mesh is gradually refined towards the wall to provide values close enough to the wall for the wall coordinate (y+). Grid resolution study has been conducted for One-Equation model. The accuracy of the results is analyzed with respect to the grid smoothness in order to reach an optimized resolution for carrying out the next simulations. Furthermore, three LES models, One-Equation, Smagorinsky and Dynamic Smagorinsky are applied for the grid resolution of (60 × 100 × 80) in (x, y, z) directions. The results are then validated with reference to the DNS carried out by Moser et al.[2] for the similar geometry using logarithmic velocity profile (U+) and Reynolds stress tensor components. In the second step the similar flow is modeled using Reynolds averaged method. Several RANS models, like K-epsilon and Launder-Reece-Rodi are applied and validated against DNS and LES results in a similar fashion. In the most recent step, it has been intended to generate an optimized LES solver to model turbulent pipe flow for larger Reynolds numbers. The validations are carried out using experiments conducted in Cottbus Large Pipe Test Facility at BTU as a reference [3]. In the mentioned experimental research, evolution of statistical pipe flow quantities, such as turbulence intensity, skewness and flatness are investigated to clarify the development length needed to achieve fully developed turbulence. These observations take place in a relatively large pipe test facility with an inner pipe diameter of Di = 0.19 m and a total length of L = 27 m where a bulk Reynolds number of 8.5×105 can be reached. 1. CO2 pipeline Infrastructure: An analysis of global challenges and opportunities, Final Report For International Energy Agency of Greenhouse Gas Program (2010) 2. J. Kim, P. Moin, R. Moser, Turbulence statistics in fully developed channel flow at low Reynolds number, J.Fluid Mech. 177, 133-166, (1987) 3. F. Zimmer, E.-S. Zanoun and C. Egbers, A study on the influence of triggering pipe flow regarding mean and higher order statistics, Journal of Physics: Conference Series 318 (2011) 032039

Detection of Fatigue Crack in Basalt FRP Laminate Composite Pipe using Electrical Potential Change Method

NASA Astrophysics Data System (ADS)

Altabey, Wael A.; Noori, Mohammed

2017-05-01

Novel modulation electrical potential change (EPC) method for fatigue crack detection in a basalt fibre reinforced polymer (FRP) laminate composite pipe is carried out in this paper. The technique is applied to a laminate pipe with an embedded crack in three layers [0º/90º/0º]s. EPC is applied for evaluating the dielectric properties of basalt FRP pipe by using an electrical capacitance sensor (ECS) to discern damages in the pipe. Twelve electrodes are mounted on the outer surface of the pipe and the changes in the modulation dielectric properties of the piping system are analyzed to detect damages in the pipe. An embedded crack is created by a fatigue internal pressure test. The capacitance values, capacitance change and node potential distribution of ECS electrodes are calculated before and after crack initiates using a finite element method (FEM) by ANSYS and MATLAB, which are combined to simulate sensor characteristics and fatigue behaviour. The crack lengths of the basalt FRP are investigated for various number of cycles to failure for determining crack growth rate. Response surfaces are adopted as a tool for solving inverse problems to estimate crack lengths from the measured electric potential differences of all segments between electrodes to validate the FEM results. The results show that, the good convergence between the FEM and estimated results. Also the results of this study show that the electrical potential difference of the basalt FRP laminate increases during cyclic loading, caused by matrix cracking. The results indicate that the proposed method successfully provides fatigue crack detection for basalt FRP laminate composite pipes.

The three-dimensional structure of swirl-switching in bent pipe flow

DOE PAGES

Hufnagel, Lorenz; Canton, Jacopo; Örlü, Ramis; ...

2017-11-27

Swirl-switching is a low-frequency oscillatory phenomenon which affects the Dean vortices in bent pipes and may cause fatigue in piping systems. Despite thirty years worth of research, the mechanism that causes these oscillations and the frequencies that characterise them remain unclear. In this paper, we show that a three-dimensional wave-like structure is responsible for the low-frequency switching of the dominant Dean vortex. The present study, performed via direct numerical simulation, focuses on the turbulent flow through amore » $$90^{\\circ }$$pipe bend preceded and followed by straight pipe segments. A pipe with curvature 0.3 (defined as ratio between pipe radius and bend radius) is studied for a bulk Reynolds number $$Re=11\\,700$$, corresponding to a friction Reynolds number $$Re_{\\unicode[STIX]{x1D70F}}\\approx 360$$. Synthetic turbulence is generated at the inflow section and used instead of the classical recycling method in order to avoid the interference between recycling and swirl-switching frequencies. The flow field is analysed by three-dimensional proper orthogonal decomposition (POD) which for the first time allows the identification of the source of swirl-switching: a wave-like structure that originates in the pipe bend. Contrary to some previous studies, the flow in the upstream pipe does not show any direct influence on the swirl-switching modes. Finally, our analysis further shows that a three-dimensional characterisation of the modes is crucial to understand the mechanism, and that reconstructions based on two-dimensional POD modes are incomplete.« less

The three-dimensional structure of swirl-switching in bent pipe flow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hufnagel, Lorenz; Canton, Jacopo; Örlü, Ramis

Swirl-switching is a low-frequency oscillatory phenomenon which affects the Dean vortices in bent pipes and may cause fatigue in piping systems. Despite thirty years worth of research, the mechanism that causes these oscillations and the frequencies that characterise them remain unclear. In this paper, we show that a three-dimensional wave-like structure is responsible for the low-frequency switching of the dominant Dean vortex. The present study, performed via direct numerical simulation, focuses on the turbulent flow through amore » $$90^{\\circ }$$pipe bend preceded and followed by straight pipe segments. A pipe with curvature 0.3 (defined as ratio between pipe radius and bend radius) is studied for a bulk Reynolds number $$Re=11\\,700$$, corresponding to a friction Reynolds number $$Re_{\\unicode[STIX]{x1D70F}}\\approx 360$$. Synthetic turbulence is generated at the inflow section and used instead of the classical recycling method in order to avoid the interference between recycling and swirl-switching frequencies. The flow field is analysed by three-dimensional proper orthogonal decomposition (POD) which for the first time allows the identification of the source of swirl-switching: a wave-like structure that originates in the pipe bend. Contrary to some previous studies, the flow in the upstream pipe does not show any direct influence on the swirl-switching modes. Finally, our analysis further shows that a three-dimensional characterisation of the modes is crucial to understand the mechanism, and that reconstructions based on two-dimensional POD modes are incomplete.« less

Equivalent Air Spring Suspension Model for Quarter-Passive Model of Passenger Vehicles.

PubMed

Abid, Haider J; Chen, Jie; Nassar, Ameen A

2015-01-01

This paper investigates the GENSIS air spring suspension system equivalence to a passive suspension system. The SIMULINK simulation together with the OptiY optimization is used to obtain the air spring suspension model equivalent to passive suspension system, where the car body response difference from both systems with the same road profile inputs is used as the objective function for optimization (OptiY program). The parameters of air spring system such as initial pressure, volume of bag, length of surge pipe, diameter of surge pipe, and volume of reservoir are obtained from optimization. The simulation results show that the air spring suspension equivalent system can produce responses very close to the passive suspension system.

Experimental Validation of a Fast Forward Model for Guided Wave Tomography of Pipe Elbows.

PubMed

Brath, Alex J; Simonetti, Francesco; Nagy, Peter B; Instanes, Geir

2017-05-01

Ultrasonic guided wave tomography (GWT) methods for the detection of corrosion and erosion damage in straight pipe sections are now well advanced. However, successful application of GWT to pipe bends has not yet been demonstrated due to the computational burden associated with the complex forward model required to simulate guided wave propagation through the bend. In a previous paper [Brath et al., IEEE Trans. Ultrason., Ferroelectr., Freq. Control, vol. 61, pp. 815-829, 2014], we have shown that the speed of the forward model can be increased by replacing the 3-D pipe bend with a 2-D rectangular domain in which guided wave propagation is formulated based on an artificially inhomogeneous and elliptically anisotropic (INELAN) acoustic model. This paper provides further experimental validation of the INLEAN model by studying the traveltime shifts caused by the introduction of shallow defects on the elbow of a pipe bend. Comparison between experiments and simulations confirms that a defect can be modeled as a phase velocity perturbation to the INLEAN velocity field with accuracy that is within the experimental error of the measurements. In addition, it is found that the sensitivity of traveltime measurements to the presence of damage decreases as the damage position moves from the interior side of the bend (intrados) to the exterior one (extrados). This effect is due to the nonuniform ray coverage obtainable when transmitting the guided wave signals with one ring array of sources on one side of the elbow and receiving with a second array on the other side.

Decoupling pipeline influences in soil resistivity measurements with finite element techniques

NASA Astrophysics Data System (ADS)

Deo, R. N.; Azoor, R. M.; Zhang, C.; Kodikara, J. K.

2018-03-01

Periodic inspection of pipeline conditions is an important asset management strategy conducted by water and sewer utilities for efficient and economical operations of their assets in field. The Level 1 pipeline condition assessment involving resistivity profiling along the pipeline right-of-way is a common technique for delineating pipe sections that might be installed in highly corrosive soil environment. However, the technique can suffer from significant perturbations arising from the buried pipe itself, resulting in errors in native soil characterisation. To address this problem, a finite element model was developed to investigate the degree to which pipes of different a) diameters, b) burial depths, and c) surface conditions (bare or coated) can influence in-situ soil resistivity measurements using Wenner methods. It was found that the greatest errors can arise when conducting measurements over a bare pipe with the array aligned parallel to the pipe. Depending upon the pipe surface conditions, in-situ resistivity measurements can either be underestimated or overestimated from true soil resistivities. Following results based on simulations and decoupling equations, a guiding framework for removing pipe influences in soil resistivity measurements were developed that can be easily used to perform corrections on measurements. The equations require simple a-prior information on the pipe diameter, burial depth, surface condition, and the array length and orientation used. Findings from this study have immediate application and is envisaged to be useful for critical civil infrastructure monitoring and assessment.

An experimental study of geyser-like flows induced by a pressurized air pocket

NASA Astrophysics Data System (ADS)

Elayeb, I. S.; Leon, A.; Choi, Y.; Alnahit, A. O.

2015-12-01

Previous studies argues that the entrapment of pressurized air pockets within combined sewer systems can produce geyser flows, which is an oscillating jetting of a mixture of gas-liquid flows. To verify that pressurized air pockets can effectively produce geysers, laboratory experiments were conducted. However, past experiments were conducted in relatively small-scale apparatus (i.e. maximum φ2" vertical shaft). This study conducted a set of experiments in a larger apparatus. The experimental setup consists of an upstream head tank, a downstream head tank, a horizontal pipe (46.5ft long, φ6") and a vertical pipe (10ft long, φ6"). The initial condition for the experiments is constant flow discharge through the horizontal pipe. The experiments are initiated by injecting an air pocket with pre-determined volume and pressure at the upstream end of the horizontal pipe. The air pocket propagates through the horizontal pipe until it arrives to the vertical shaft, where it is released producing a geyser-like flow. Three flow rates in the horizontal pipe and three injected air pressures were tested. The variables measured were pressure at two locations in the horizontal pipe and two locations in the vertical pipe. High resolution videos at two regions in the vertical shaft were also recorded. To gain further insights in the physics of air-water interaction, the laboratory experiments were complemented with numerical simulations conducted using a commercial 3D CFD model, previously validated with experiments.

The use of adaptable automation: Effects of extended skill lay-off and changes in system reliability.

PubMed

Sauer, Juergen; Chavaillaz, Alain

2017-01-01

This experiment aimed to examine how skill lay-off and system reliability would affect operator behaviour in a simulated work environment under wide-range and large-choice adaptable automation comprising six different levels. Twenty-four participants were tested twice during a 2-hr testing session, with the second session taking place 8 months after the first. In the middle of the second testing session, system reliability changed. The results showed that after the retention interval trust increased and self-confidence decreased. Complacency was unaffected by the lay-off period. Diagnostic speed slowed down after the retention interval but diagnostic accuracy was maintained. No difference between experimental conditions was found for automation management behaviour (i.e. level of automation chosen and frequency of switching between levels). There were few effects of system reliability. Overall, the findings showed that subjective measures were more sensitive to the impact of skill lay-off than objective behavioural measures. Copyright © 2016 Elsevier Ltd. All rights reserved.

Assessing recovery feasibility for piping plovers using optimization and simulation

USGS Publications Warehouse

Larson, M.A.; Ryan, M.R.; Murphy, R.K.

2003-01-01

Optimization and simulation modeling can be used to account for demographic and economic factors simultaneously in a comprehensive analysis of endangered-species population recovery. This is a powerful approach that is broadly applicable but underutilized in conservation biology. We applied the approach to a population recovery analysis of threatened and endangered piping plovers (Charadrius melodus) in the Great Plains of North America. Predator exclusion increases the reproductive success of piping plovers, but the most cost-efficient strategy of applying predator exclusion and the number of protected breeding pairs necessary to prevent further population declines were unknown. We developed a linear programming model to define strategies that would either maximize fledging rates or minimize financial costs by allocating plover pairs to 1 of 6 types of protection. We evaluated the optimal strategies using a stochastic population simulation model. The minimum cost to achieve a 20% chance of stabilizing simulated populations was approximately $1-11 million over 50 years. Increasing reproductive success to 1.24 fledglings/pair at minimal cost in any given area required fencing 85% of pairs at managed sites but cost 23% less than the current approach. Maximum fledging rates resulted in >20% of simulated populations reaching recovery goals in 30-50 years at cumulative costs of <$16 million. Protecting plover pairs within 50 km of natural resource agency field offices was sufficient to increase simulated populations to established recovery goals. A range-wide management plan needs to be developed and implemented to foster the involvement and cooperation among managers that will be necessary for recovery efforts to be successful. We also discuss how our approach can be applied to a variety of wildlife management issues.

Three dimensional contact/impact methodology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kulak, R.F.

1987-01-01

The simulation of three-dimensional interface mechanics between reactor components and structures during static contact or dynamic impact is necessary to realistically evaluate their structural integrity to off-normal loads. In our studies of postulated core energy release events, we have found that significant structure-structure interactions occur in some reactor vessel head closure designs and that fluid-structure interactions occur within the reactor vessel. Other examples in which three-dimensional interface mechanics play an important role are: (1) impact response of shipping casks containing spent fuel, (2) whipping pipe impact on reinforced concrete panels or pipe-to-pipe impact after a pipe break, (3) aircraft crashmore » on secondary containment structures, (4) missiles generated by turbine failures or tornados, and (5) drops of heavy components due to lifting accidents. The above is a partial list of reactor safety problems that require adequate treatment of interface mechanics and are discussed in this paper.« less

Leak Detection and Location of Water Pipes Using Vibration Sensors and Modified ML Prefilter.

PubMed

Choi, Jihoon; Shin, Joonho; Song, Choonggeun; Han, Suyong; Park, Doo Il

2017-09-13

This paper proposes a new leak detection and location method based on vibration sensors and generalised cross-correlation techniques. Considering the estimation errors of the power spectral densities (PSDs) and the cross-spectral density (CSD), the proposed method employs a modified maximum-likelihood (ML) prefilter with a regularisation factor. We derive a theoretical variance of the time difference estimation error through summation in the discrete-frequency domain, and find the optimal regularisation factor that minimises the theoretical variance in practical water pipe channels. The proposed method is compared with conventional correlation-based techniques via numerical simulations using a water pipe channel model, and it is shown through field measurement that the proposed modified ML prefilter outperforms conventional prefilters for the generalised cross-correlation. In addition, we provide a formula to calculate the leak location using the time difference estimate when different types of pipes are connected.

Leak Detection and Location of Water Pipes Using Vibration Sensors and Modified ML Prefilter

PubMed Central

Shin, Joonho; Song, Choonggeun; Han, Suyong; Park, Doo Il

2017-01-01

This paper proposes a new leak detection and location method based on vibration sensors and generalised cross-correlation techniques. Considering the estimation errors of the power spectral densities (PSDs) and the cross-spectral density (CSD), the proposed method employs a modified maximum-likelihood (ML) prefilter with a regularisation factor. We derive a theoretical variance of the time difference estimation error through summation in the discrete-frequency domain, and find the optimal regularisation factor that minimises the theoretical variance in practical water pipe channels. The proposed method is compared with conventional correlation-based techniques via numerical simulations using a water pipe channel model, and it is shown through field measurement that the proposed modified ML prefilter outperforms conventional prefilters for the generalised cross-correlation. In addition, we provide a formula to calculate the leak location using the time difference estimate when different types of pipes are connected. PMID:28902154

Large Eddy Simulation of Supercritical CO2 Through Bend Pipes

NASA Astrophysics Data System (ADS)

He, Xiaoliang; Apte, Sourabh; Dogan, Omer

2017-11-01

Supercritical Carbon Dioxide (sCO2) is investigated as working fluid for power generation in thermal solar, fossil energy and nuclear power plants at high pressures. Severe erosion has been observed in the sCO2 test loops, particularly in nozzles, turbine blades and pipe bends. It is hypothesized that complex flow features such as flow separation and property variations may lead to large oscillations in the wall shear stresses and result in material erosion. In this work, large eddy simulations are conducted at different Reynolds numbers (5000, 27,000 and 50,000) to investigate the effect of heat transfer in a 90 degree bend pipe with unit radius of curvature in order to identify the potential causes of the erosion. The simulation is first performed without heat transfer to validate the flow solver against available experimental and computational studies. Mean flow statistics, turbulent kinetic energy, shear stresses and wall force spectra are computed and compared with available experimental data. Formation of counter-rotating vortices, named Dean vortices, are observed. Secondary flow pattern and swirling-switching flow motions are identified and visualized. Effects of heat transfer on these flow phenomena are then investigated by applying a constant heat flux at the wall. DOE Fossil Energy Crosscutting Technology Research Program.

LBflow: An extensible lattice Boltzmann framework for the simulation of geophysical flows. Part II: usage and validation

NASA Astrophysics Data System (ADS)

Llewellin, E. W.

2010-02-01

LBflow is a flexible, extensible implementation of the lattice Boltzmann method, developed with geophysical applications in mind. The theoretical basis for LBflow, and its implementation, are presented in the companion paper, 'Part I'. This article covers the practical usage of LBflow and presents guidelines for obtaining optimal results from available computing power. The relationships among simulation resolution, accuracy, runtime and memory requirements are investigated in detail. Particular attention is paid to the origin, quantification and minimization of errors. LBflow is validated against analytical, numerical and experimental results for a range of three-dimensional flow geometries. The fluid conductance of prismatic pipes with various cross sections is calculated with LBflow and found to be in excellent agreement with published results. Simulated flow along sinusoidally constricted pipes gives good agreement with experimental data for a wide range of Reynolds number. The permeability of packs of spheres is determined and shown to be in excellent agreement with analytical results. The accuracy of internal flow patterns within the investigated geometries is also in excellent quantitative agreement with published data. The development of vortices within a sinusoidally constricted pipe with increasing Reynolds number is shown, demonstrating the insight that LBflow can offer as a 'virtual laboratory' for fluid flow.

The Second International Piping Integrity Research Group (IPIRG-2) program. Final report, October 1991--April 1996

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hopper, A.; Wilowski, G.; Scott, P.

1997-03-01

The IPIRG-2 program was an international group program managed by the US NRC and funded by organizations from 15 nations. The emphasis of the IPIRG-2 program was the development of data to verify fracture analyses for cracked pipes and fittings subjected to dynamic/cyclic load histories typical of seismic events. The scope included: (1) the study of more complex dynamic/cyclic load histories, i.e., multi-frequency, variable amplitude, simulated seismic excitations, than those considered in the IPIRG-1 program, (2) crack sizes more typical of those considered in Leak-Before-Break (LBB) and in-service flaw evaluations, (3) through-wall-cracked pipe experiments which can be used to validatemore » LBB-type fracture analyses, (4) cracks in and around pipe fittings, such as elbows, and (5) laboratory specimen and separate effect pipe experiments to provide better insight into the effects of dynamic and cyclic load histories. Also undertaken were an uncertainty analysis to identify the issues most important for LBB or in-service flaw evaluations, updating computer codes and databases, the development and conduct of a series of round-robin analyses, and analyst`s group meetings to provide a forum for nuclear piping experts from around the world to exchange information on the subject of pipe fracture technology. 17 refs., 104 figs., 41 tabs.« less

Studies on the influence of axial bends on ultrasonic guided waves in hollow cylinders (pipes)

NASA Astrophysics Data System (ADS)

Verma, Bhupesh; Balasubramaniam, Krishnan; Rajagopal, Prabhu

2013-01-01

Ultrasonic guided waves in hollow cylinders (pipes) are today widely applied as rapid screening tools in the inspection of straight pipe segments in oil, power generation and petrochemical processing industries. However, the characteristics of guided wave propagation across features such as bends in the pipe network are complicated, hampering a wider application of the developed techniques. Although a growing number of studies in recent years have considered guided wave propagation across elbows and U-type bends, the topic is still not very well understood for a general bend angle φ, mean bend radius R and pipe thickness b. Here we use 3D Finite Element (FE) simulation to illumine the propagation of fundamental guided pipe modes across bends of several different angles φ. Two different bend radius regimes, R/λ ≈ 1 and 10 (where λ denotes the wavelength of the mode studied) are considered, exemplifying 'sharp' and gradual or 'slow' bends. Different typical pipe thicknesses b within these regimes are also studied. The results confirm the expectation that different bend radius regimes affect the waves differently. Further, while as observed in earlier studies, at moderate bend radii, fundamental modes travel almost unaffected by an elbow (bend angle φ = 90 degrees), we find that as the bend angle is reduced, there is a progressively larger extent of mode-conversion. These trends and results are validated using experiments.

Protection of Buried Pipe under Repeated Loading by Geocell Reinforcement

NASA Astrophysics Data System (ADS)

Khalaj, Omid; Joz Darabi, N.; Moghaddas Tafreshi, S. N.; Mašek, Bohuslav

2017-12-01

With increase in cities’ population and development of urbane life, passing buried pipelines near ground’s surface is inevitable in urban areas, roads, subways and highways. This paper presents the results of three-dimensional full scale model tests on high-density polyethylene (HDPE) pipe with diameter of 250 mm in geocell reinforced soil, subjected to repeated loading to simulate the vehicle loads. The effect of geocell’s pocket size (55*55 mm and 110*110 mm) and embedment depth of buried pipe (1.5 and 2 times pipe diameter) in improving the behaviour of buried pipes was investigated. The geocell’s height of 100 mm was used in all tests. The repeated load of 800 kPa was applied on circular loading plate with diameter of 250 mm. The results show that the pipe displacement, soil surface settlement and transferred pressure on the pipe’s crown has been influenced significantly upon the use of geocells. For example, the vertical diametric strain (VDS) and soil surface settlement (SSS), in a way that using a geocell with pocket size of 110*110 mm reduces by 27% and 43%, respectively, compared with the unreinforced one. Meanwhile, by increasing buried depth of pipe from 1.5D to 2D, the use of geocell of 110*110 mm delivers about 50% reduction in SSS and VDS, compared with the unreinforced soil.

GROWTH OF HETROTROPHIC BIOFILMS IN A WATER DISTRIBUTION SYSTEM SIMULATOR

EPA Science Inventory

The U.S. EPA has designed and constructed a distribution system simulator (DSS) to evaluate factors which influence water quality within water distribution systems. Six individual 25 meter lengths of 15 cm diameter ductile iron pipe are arranged into loop configurations. Each lo...

Welding High Strength Modern Line Pipe Steel

NASA Astrophysics Data System (ADS)

Goodall, Graeme Robertson

The effect of modern mechanized girth welding on high strength line pipe has been investigated. The single cycle grain coarsened heat affected zone in three grade 690 line pipe steels and a grade 550 steel has been simulated using a Gleeble thermo-mechanical simulator. The continuous cooling transformation diagrams applicable to the grain coarsened heat affected zone resulting from a range of heat inputs applicable to modern mechanized welding have been established by dilatometry and metallography. The coarse grained heat affected zone was found to transform to lath martensite, bainite, and granular bainite depending on the cooling rate. The impact toughness of the steels was measured using Charpy impact toughness and compared to the toughness of the grain coarsened heat affected zone corresponding to a welding thermal cycle. The ductile to brittle transition temperature was found to be lowest for the steel with the highest hardenability. The toughness resulting from three different thermal cycles including a novel interrupted intercritically reheated grain coarsened (NTR ICR GC HAZ) that can result from dual torch welding at fast travel speed and close torch spacing have been investigated. All of the thermally HAZ regions showed reduced toughness that was attributed to bainitic microstructure and large effective grain sizes. Continuous cooling transformation diagrams for five weld metal chemistries applicable to mechanized pulsed gas metal arc welding of modern high strength pipe steel (SMYS>550 MPa) have been constructed. Welds at heat inputs of 1.5 kJmm-1 and 0.5 kJmm-1 have been created for simulation and analysis. Dilatometric analysis was performed on weld metal specimens cut from single pass 1.5 kJmm-1 as deposited beads. The resulting microstructures were found to range from martensite to polygonal ferrite. There is excellent agreement between the simulated and as deposited weld metal regions. Toughness testing indicates improved energy absorption at -20 °C with increased cooling time.

Thermal Insulation Performance of Flexible Piping for Use in HTS Power Cables

NASA Technical Reports Server (NTRS)

Fesmire, James E.; Augustynowicz, S. D.; Demko, J. A.; Thompson, Karen (Technical Monitor)

2001-01-01

High-temperature superconducting (HTS) cables that typically operate at temperatures below 80 K are being developed for power transmission. The practical application of HTS power cables will require the use of flexible piping to contain the cable and the liquid nitrogen coolant. A study of thermal performance of multilayer insulation (MLI) was conducted in geometries representing both rigid and flexible piping. This experimental study performed at the Cryogenics Test Laboratory of NASA Kennedy Space Center provides a framework for the development of cost-effective, efficient thermal insulation systems that will support these long-distance flexible lines containing HTS power cables. The overall thermal performance of the insulation system for a rigid configuration and for a flexible configuration, simulating a flexible HTS power cable, was determined by the steady-state liquid nitrogen boiloff method under the full range of vacuum levels. Two different cylindrically rolled material systems were tested: a standard MLI and a layered composite insulation (LCI). Comparisons of ideal MLI, MLI on rigid piping, and MLI between flexible piping are presented.

Modelling and simulation of heat pipes with TAIThermIR (Conference Presentation)

NASA Astrophysics Data System (ADS)

Winkelmann, Max E.

2016-10-01

Regarding thermal camouflage usually one has to reduce the surface temperature of an object. All vehicles and installations having a combustion engine usually produce a lot of heat with results on hot spots on the surface which are highly conspicuous. Using heat pipes to transfer this heat to another place on the surface more efficiently might be a way to reduce those hotspots and the overall conspicuity. In a first approach, a model for the Software TAIThermIR was developed to test which parameters of the heat pipes are relevant and what effects can be achieved. It will be shown, that the thermal resistivity of contact zones are quite relevant and the thermal coupling of the engine (source of heat) defines if the alteration of the thermal signature is large or not. Furthermore the impact of the use of heat pipes in relation to surface material is discussed. The influence of different weather scenarios on the change of signatures due to the use of heat pipes is of minor relevance and depends on the choice of the surface material. Finally application issues for real systems are discussed.

Quality of dispatch-assisted cardiopulmonary resuscitation by lay rescuers following a standard protocol in Japan: an observational simulation study.

PubMed

Asai, Hideki; Fukushima, Hidetada; Bolstad, Francesco; Okuchi, Kazuo

2018-04-01

Bystander cardiopulmonary resuscitation (CPR) is essential for improving the outcomes of sudden cardiac arrest patients. It has been reported that dispatch-assisted CPR (DACPR) accounts for more than half of the incidence of CPR undertaken by bystanders. Its quality, however, can be suboptimal. We aimed to measure the quality of DACPR using a simulation study. We recruited laypersons at a shopping mall and measured the quality of CPR carried out in our simulation. Dispatchers provided instruction in accordance with the standard DACPR protocol in Japan. Twenty-three laypersons (13 with CPR training experience within the past 2 years and 10 with no training experience) participated in this study. The median chest compression rate and depth were 106/min and 33 mm, respectively. The median time interval from placing the 119 call to the start of chest compressions was 119 s. No significant difference was found between the groups with and without training experience. However, subjects with training experience more frequently placed their hands correctly on the manikin (84.6% versus 40.0%; P = 0.026). Twelve participants (52.2%, seven in trained and five in untrained group) interrupted chest compressions for 3-18 s, because dispatchers asked if the patient started breathing or moving. This current simulation study showed that the quality of DACPR carried out by lay rescuers can be less than optimal in terms of depth, hand placement, and minimization of pauses. Further studies are required to explore better DACPR instruction methods to help lay rescuers perform CPR with optimal quality.

On the formation, growth, and shapes of solution pipes - insights from numerical modeling

NASA Astrophysics Data System (ADS)

Szymczak, Piotr; Tredak, Hanna; Upadhyay, Virat; Kondratiuk, Paweł; Ladd, Anthony J. C.

2015-04-01

Cylindrical, vertical structures called solution pipes are a characteristic feature of epikarst, encountered in different parts of the world, both in relatively cold areas such as England and Poland (where their formation is linked to glacial processes) [1] and in coastal areas in tropical or subtropical climate (Bermuda, Australia, South Africa, Caribbean, Mediterranean) [2,3]. They are invariably associated with weakly cemented, porous limestones and relatively high groundwater fluxes. Many of them develop under the colluvial sandy cover and contain the fill of clayey silt. Although it is widely accepted that they are solutional in origin, the exact mechanism by which the flow becomes focused is still under debate. The hypotheses include the concentration of acidified water around stems and roots of plants, or the presence of pre-existing fractures or steeply dipping bedding planes, which would determine the points of entry for the focused groundwater flows. However, there are field sites where neither of this mechanisms was apparently at play and yet the pipes are formed in large quantities [1]. In this communication we show that the systems of solution pipes can develop spontaneously in nearly uniform matrix due to the reactive-infiltration instability: a homogeneous porous matrix is unstable with respect to small variations in local permeability; regions of high permeability dissolve faster because of enhanced transport of reactants, which leads to increased rippling of the front. This leads to the formation of a system of solution pipes which then advance into the matrix. We study this process numerically, by a combination of 2d- and 3d-simulations, solving the coupled flow and transport equations at the Darcy scale. The relative simplicity of this system (pipes developing in a uniform porous matrix, without any pre-existing structure) makes it very attractive from the modeling standpoint. We quantify the factors which control the pipe diameters and the distances between the pipes as well as their growth rates. The most interesting result is the existence of two different regimes of the piped growth, depending on the flow rate. At high flow rates, well-separated, cyllindrical shafts are formed, of a nearly uniform diameter all along their lengths. They advance quickly into the matrix, with velocities several times larger than that of a unperturbed, planar dissolution front. Conversely, for small flow rates, the pipes are funnel-shaped with parabolic tips and their advancement velocity is of the same order as that of a planar front. The transition between the two forms is abrupt, with no intermediate forms observed. The simulation results are compared with field evidence from limestone quarries in Smerdyna, Poland, where several hundred of solution pipes have been exposed. Interestingly, both forms (shaft-like and tunnel-like) are found in the field, sometimes in close proximity to each other. [1] P. Walsh and I. Morawiecka-Zacharz, A dissolution pipe palaeokarst of mid-Pleistocene age preserved in Miocene limestones near Staszow, Poland, Palaeogeogr. Palaeoclimatol. Palaeoecol., 174 (2001), pp. 327-350. [2] K. G. Grimes, Solution pipes and pinnacles in syngenetic karst. In: Gines A., Knez M., Slabe T., Dreybrodt W. (Eds.), Karst Rock Features: Karren Sculpturing. Ljubljana, ZRC Publishing, (2009), pp. 513-523. [3] J. De Waele, S. E. Lauritzen and M. Parise On the formation of dissolution pipes in Quaternary coastal calcareous arenites in Mediterranean settings. Earth. Surf. Proc. Land" 36, (2011), pp. 143-157.

Storm Water Management Model Reference Manual Volume II ...

EPA Pesticide Factsheets

SWMM is a dynamic rainfall-runoff simulation model used for single event or long-term (continuous) simulation of runoff quantity and quality from primarily urban areas. The runoff component of SWMM operates on a collection of subcatchment areas that receive precipitation and generate runoff and pollutant loads. The routing portion of SWMM transports this runoff through a system of pipes, channels, storage/treatment devices, pumps, and regulators. SWMM tracks the quantity and quality of runoff generated within each subcatchment, and the flow rate, flow depth, and quality of water in each pipe and channel during a simulation period comprised of multiple time steps. The reference manual for this edition of SWMM is comprised of three volumes. Volume I describes SWMM’s hydrologic models, Volume II its hydraulic models, and Volume III its water quality and low impact development models. This document provides the underlying mathematics for the hydraulic calculations of the Storm Water Management Model (SWMM)

Electrically Heated Testing of the Kilowatt Reactor Using Stirling Technology (KRUSTY) Experiment Using a Depleted Uranium Core

NASA Technical Reports Server (NTRS)

Briggs, Maxwell H.; Gibson, Marc A.; Sanzi, James

2017-01-01

The Kilopower project aims to develop and demonstrate scalable fission-based power technology for systems capable of delivering 110 kW of electric power with a specific power ranging from 2.5 - 6.5 Wkg. This technology could enable high power science missions or could be used to provide surface power for manned missions to the Moon or Mars. NASA has partnered with the Department of Energys National Nuclear Security Administration, Los Alamos National Labs, and Y-12 National Security Complex to develop and test a prototypic reactor and power system using existing facilities and infrastructure. This technology demonstration, referred to as the Kilowatt Reactor Using Stirling TechnologY (KRUSTY), will undergo nuclear ground testing in the summer of 2017 at the Nevada Test Site. The 1 kWe variation of the Kilopower system was chosen for the KRUSTY demonstration. The concept for the 1 kWe flight system consist of a 4 kWt highly enriched Uranium-Molybdenum reactor operating at 800 degrees Celsius coupled to sodium heat pipes. The heat pipes deliver heat to the hot ends of eight 125 W Stirling convertors producing a net electrical output of 1 kW. Waste heat is rejected using titanium-water heat pipes coupled to carbon composite radiator panels. The KRUSTY test, based on this design, uses a prototypic highly enriched uranium-molybdenum core coupled to prototypic sodium heat pipes. The heat pipes transfer heat to two Advanced Stirling Convertors (ASC-E2s) and six thermal simulators, which simulate the thermal draw of full scale power conversion units. Thermal simulators and Stirling engines are gas cooled. The most recent project milestone was the completion of non-nuclear system level testing using an electrically heated depleted uranium (non-fissioning) reactor core simulator. System level testing at the Glenn Research Center (GRC) has validated performance predictions and has demonstrated system level operation and control in a test configuration that replicates the one to be used at the Device Assembly Facility (DAF) at the Nevada National Security Site. Fabrication, assembly, and testing of the depleted uranium core has allowed for higher fidelity system level testing at GRC, and has validated the fabrication methods to be used on the highly enriched uranium core that will supply heat for the DAF KRUSTY demonstration.

In-pipe aerodynamic characteristics of a projectile in comparison with free flight for transonic Mach numbers

NASA Astrophysics Data System (ADS)

Hruschka, R.; Klatt, D.

2018-03-01

The transient shock dynamics and drag characteristics of a projectile flying through a pipe 3.55 times larger than its diameter at transonic speed are analyzed by means of time-of-flight and pipe wall pressure measurements as well as computational fluid dynamics (CFD). In addition, free-flight drag of the 4.5-mm-pellet-type projectile was also measured in a Mach number range between 0.5 and 1.5, providing a means for comparison against in-pipe data and CFD. The flow is categorized into five typical regimes the in-pipe projectile experiences. When projectile speed and hence compressibility effects are low, the presence of the pipe has little influence on the drag. Between Mach 0.5 and 0.8, there is a strong drag increase due to the presence of the pipe, however, up to a value of about two times the free-flight drag. This is exactly where the nose-to-base pressure ratio of the projectile becomes critical for locally sonic speed, allowing the drag to be estimated by equations describing choked flow through a converging-diverging nozzle. For even higher projectile Mach numbers, the drag coefficient decreases again, to a value slightly below the free-flight drag at Mach 1.5. This behavior is explained by a velocity-independent base pressure coefficient in the pipe, as opposed to base pressure decreasing with velocity in free flight. The drag calculated by CFD simulations agreed largely with the measurements within their experimental uncertainty, with some discrepancies remaining for free-flying projectiles at supersonic speed. Wall pressure measurements as well as measured speeds of both leading and trailing shocks caused by the projectile in the pipe also agreed well with CFD.

Electron Cloud in Steel Beam Pipe vs Titanium Nitride Coated and Amorphous Carbon Coated Beam Pipes in Fermilab's Main Injector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Backfish, Michael

This paper documents the use of four retarding field analyzers (RFAs) to measure electron cloud signals created in Fermilab’s Main Injector during 120 GeV operations. The first data set was taken from September 11, 2009 to July 4, 2010. This data set is used to compare two different types of beam pipe that were installed in the accelerator. Two RFAs were installed in a normal steel beam pipe like the rest of the Main Injector while another two were installed in a one meter section of beam pipe that was coated on the inside with titanium nitride (TiN). A secondmore » data run started on August 23, 2010 and ended on January 10, 2011 when Main Injector beam intensities were reduced thus eliminating the electron cloud. This second run uses the same RFA setup but the TiN coated beam pipe was replaced by a one meter section coated with amorphous carbon (aC). This section of beam pipe was provided by CERN in an effort to better understand how an aC coating will perform over time in an accelerator. The research consists of three basic parts: (a) continuously monitoring the conditioning of the three different types of beam pipe over both time and absorbed electrons (b) measurement of the characteristics of the surrounding magnetic fields in the Main Injector in order to better relate actual data observed in the Main Injector with that of simulations (c) measurement of the energy spectrum of the electron cloud signals using retarding field analyzers in all three types of beam pipe.« less

Three-dimensional analysis for liquid hydrogen in a cryogenic storage tank with heat pipe pump system

NASA Astrophysics Data System (ADS)

Ho, Son H.; Rahman, Muhammad M.

2008-01-01

This paper presents a study on fluid flow and heat transfer of liquid hydrogen in a zero boil-off cryogenic storage tank in a microgravity environment. The storage tank is equipped with an active cooling system consisting of a heat pipe and a pump-nozzle unit. The pump collects cryogen at its inlet and discharges it through its nozzle onto the evaporator section of the heat pipe in order to prevent the cryogen from boiling off due to the heat leaking through the tank wall from the surroundings. A three-dimensional (3-D) finite element model is employed in a set of numerical simulations to solve for velocity and temperature fields of liquid hydrogen in steady state. Complex structures of 3-D velocity and temperature distributions determined from the model are presented. Simulations with an axisymmetric model were also performed for comparison. Parametric study results from both models predict that as the speed of the cryogenic fluid discharged from the nozzle increases, the mean or bulk cryogenic fluid speed increases linearly and the maximum temperature within the cryogenic fluid decreases.

Guided wave imaging of oblique reflecting interfaces in pipes using common-source synthetic focusing

NASA Astrophysics Data System (ADS)

Sun, Zeqing; Sun, Anyu; Ju, Bing-Feng

2018-04-01

Cross-mode-family mode conversion and secondary reflection of guided waves in pipes complicate the processing of guided waves signals, and can cause false detection. In this paper, filters operating in the spectral domain of wavenumber, circumferential order and frequency are designed to suppress the signal components of unwanted mode-family and unwanted traveling direction. Common-source synthetic focusing is used to reconstruct defect images from the guided wave signals. Simulations of the reflections from linear oblique defects and a semicircle defect are separately implemented. Defect images, which are reconstructed from the simulation results under different excitation conditions, are comparatively studied in terms of axial resolution, reflection amplitude, detectable oblique angle and so on. Further, the proposed method is experimentally validated by detecting linear cracks with various oblique angles (10-40°). The proposed method relies on the guided wave signals that are captured during 2-D scanning of a cylindrical area on the pipe. The redundancy of the signals is analyzed to reduce the time-consumption of the scanning process and to enhance the practicability of the proposed method.

Thermal Performance of Cryogenic Piping Multilayer Insulation in Actual Field Installations

NASA Technical Reports Server (NTRS)

Fesmire, J.; Augustnynowicz, S.; Thompson, K. (Technical Monitor)

2002-01-01

A standardized way of comparing the thermal performance of different pipelines in different sizes is needed. Vendor data for vacuum-insulated piping are typically given in heat leak rate per unit length (W/m) for a specific diameter pipeline. An overall k-value for actual field installations (k(sub oafi)) is therefore proposed as a more generalized measure for thermal performance comparison and design calculation. The k(sub oafi) provides a direct correspondence to the k-values reported for insulation materials and illustrates the large difference between ideal multilayer insulation (MLI) and actual MLI performance. In this experimental research study, a section of insulated piping was tested under cryogenic vacuum conditions, including simulated spacers and bending. Several different insulation systems were tested using a 1-meter-long cylindrical cryostat test apparatus. The simulated spacers tests showed significant degradation in the thermal performance of a given insulation system. An 18-meter-long pipeline test apparatus is now in operation at the Cryogenics Test Laboratory, NASA Kennedy Space Center, for conducting liquid nitrogen thermal performance tests.

A Time-Variant Reliability Model for Copper Bending Pipe under Seawater-Active Corrosion Based on the Stochastic Degradation Process

PubMed Central

Li, Mengmeng; Feng, Qiang; Yang, Dezhen

2018-01-01

In the degradation process, the randomness and multiplicity of variables are difficult to describe by mathematical models. However, they are common in engineering and cannot be neglected, so it is necessary to study this issue in depth. In this paper, the copper bending pipe in seawater piping systems is taken as the analysis object, and the time-variant reliability is calculated by solving the interference of limit strength and maximum stress. We did degradation experiments and tensile experiments on copper material, and obtained the limit strength at each time. In addition, degradation experiments on copper bending pipe were done and the thickness at each time has been obtained, then the response of maximum stress was calculated by simulation. Further, with the help of one kind of Monte Carlo method we propose, the time-variant reliability of copper bending pipe was calculated based on the stochastic degradation process and interference theory. Compared with traditional methods and verified by maintenance records, the results show that the time-variant reliability model based on the stochastic degradation process proposed in this paper has better applicability in the reliability analysis, and it can be more convenient and accurate to predict the replacement cycle of copper bending pipe under seawater-active corrosion. PMID:29584695

Equivalent Air Spring Suspension Model for Quarter-Passive Model of Passenger Vehicles

PubMed Central

Abid, Haider J.; Chen, Jie; Nassar, Ameen A.

2015-01-01

This paper investigates the GENSIS air spring suspension system equivalence to a passive suspension system. The SIMULINK simulation together with the OptiY optimization is used to obtain the air spring suspension model equivalent to passive suspension system, where the car body response difference from both systems with the same road profile inputs is used as the objective function for optimization (OptiY program). The parameters of air spring system such as initial pressure, volume of bag, length of surge pipe, diameter of surge pipe, and volume of reservoir are obtained from optimization. The simulation results show that the air spring suspension equivalent system can produce responses very close to the passive suspension system. PMID:27351020

Modeling of a CeO2 thermochemistry reduction process for hydrogen production by solar concentrated energy

NASA Astrophysics Data System (ADS)

Valle-Hernández, Julio; Romero-Paredes, Hernando; Arancibia-Bulnes, Camilo A.; Villafan-Vidales, Heidi I.; Espinosa-Paredes, Gilberto

2016-05-01

In this paper the simulation of the thermal reduction for hydrogen production through the decomposition of cerium oxide is presented. The thermochemical cycle for hydrogen production consists of the endothermic reduction of CeO2 at high temperature, where concentrated solar energy is used as a source of heat; and of the subsequent steam hydrolysis of the resulting cerium oxide to produce hydrogen. For the thermochemical process, a solar reactor prototype is proposed; consisting of a cubic receptacle made of graphite fiber thermally insulated. Inside the reactor a pyramidal arrangement with nine tungsten pipes is housed. The pyramidal arrangement is made respect to the focal point where the reflected energy is concentrated. The solar energy is concentrated through the solar furnace of high radiative flux. The endothermic step is the reduction of the cerium oxide to lower-valence cerium oxide, at very high temperature. The exothermic step is the hydrolysis of the cerium oxide (III) to form H2 and the corresponding initial cerium oxide made at lower temperature inside the solar reactor. For the modeling, three sections of the pipe where the reaction occurs were considered; the carrier gas inlet, the porous medium and the reaction products outlet. The mathematical model describes the fluid mechanics; mass and energy transfer occurring therein inside the tungsten pipe. Thermochemical process model was simulated in CFD. The results show a temperature distribution in the solar reaction pipe and allow obtaining the fluid dynamics and the heat transfer within the pipe. This work is part of the project "Solar Fuels and Industrial Processes" from the Mexican Center for Innovation in Solar Energy (CEMIE-Sol).

Overdamped large-eddy simulations of turbulent pipe flow up to Reτ = 1500

NASA Astrophysics Data System (ADS)

Feldmann, Daniel; Avila, Marc

2018-04-01

We present results from large-eddy simulations (LES) of turbulent pipe flow in a computational domain of 42 radii in length. Wide ranges of shear the Reynolds number and Smagorinsky model parameter are covered, 180 ≤ Reτ ≤ 1500 and 0.05 ≤ Cs ≤ 1.2, respectively. The aim is to asses the effect of Cs on the resolved flow field and turbulence statistics as well as to test whether very large scale motions (VLSM) in pipe flow can be isolated from the near-wall cycle by enhancing the dissipative character of the static Smagorinsky model with elevated Cs values. We found that the optimal Cs to achieve best agreement with reference data varies with Reτ and further depends on the wall normal location and the quantity of interest. Furthermore, for increasing Reτ , the optimal Cs for pipe flow LES seems to approach the theoretically optimal value for LES of isotropic turbulence. In agreement with previous studies, we found that for increasing Cs small-scale streaks in simple flow field visualisations are gradually quenched and replaced by much larger smooth streaks. Our analysis of low-order turbulence statistics suggests, that these structures originate from an effective reduction of the Reynolds number and thus represent modified low-Reynolds number near-wall streaks rather than VLSM. We argue that overdamped LES with the static Smagorinsky model cannot be used to unambiguously determine the origin and the dynamics of VLSM in pipe flow. The approach might be salvaged by e.g. using more sophisticated LES models accounting for energy flux towards large scales or explicit anisotropic filter kernels.

Direct Numerical Simulation of Incompressible Pipe Flow Using a B-Spline Spectral Method

NASA Technical Reports Server (NTRS)

Loulou, Patrick; Moser, Robert D.; Mansour, Nagi N.; Cantwell, Brian J.

1997-01-01

A numerical method based on b-spline polynomials was developed to study incompressible flows in cylindrical geometries. A b-spline method has the advantages of possessing spectral accuracy and the flexibility of standard finite element methods. Using this method it was possible to ensure regularity of the solution near the origin, i.e. smoothness and boundedness. Because b-splines have compact support, it is also possible to remove b-splines near the center to alleviate the constraint placed on the time step by an overly fine grid. Using the natural periodicity in the azimuthal direction and approximating the streamwise direction as periodic, so-called time evolving flow, greatly reduced the cost and complexity of the computations. A direct numerical simulation of pipe flow was carried out using the method described above at a Reynolds number of 5600 based on diameter and bulk velocity. General knowledge of pipe flow and the availability of experimental measurements make pipe flow the ideal test case with which to validate the numerical method. Results indicated that high flatness levels of the radial component of velocity in the near wall region are physical; regions of high radial velocity were detected and appear to be related to high speed streaks in the boundary layer. Budgets of Reynolds stress transport equations showed close similarity with those of channel flow. However contrary to channel flow, the log layer of pipe flow is not homogeneous for the present Reynolds number. A topological method based on a classification of the invariants of the velocity gradient tensor was used. Plotting iso-surfaces of the discriminant of the invariants proved to be a good method for identifying vortical eddies in the flow field.

Effect of fuel volatility on performance of tail-pipe burner

NASA Technical Reports Server (NTRS)

Barson, Zelmar; Sargent, Arthur F , Jr

1951-01-01

Fuels having Reid vapor pressures of 6.3 and 1.0 pounds per square inch were investigated in a tail-pipe burner on an axial-flow-type turbojet engine at a simulated flight Mach number of 0.6 and altitudes from 20,000 to 45,000 feet. With the burner configuration used in this investigation, having a mixing length of only 8 inches between the fuel manifold and the flame holder, the low-vapor-pressure fuel gave lower combustion efficiency at a given tail-pipe fuel-air ratio. Because the exhaust-nozzle area was fixed, the lower efficiency resulted in lower thrust and higher specific fuel consumption. The maximum altitude at which the burner would operate was practically unaffected by the change in fuel volatility.

Microseismic response characteristics modeling and locating of underground water supply pipe leak

NASA Astrophysics Data System (ADS)

Wang, J.; Liu, J.

2015-12-01

In traditional methods of pipeline leak location, geophones must be located on the pipe wall. If the exact location of the pipeline is unknown, the leaks cannot be identified accurately. To solve this problem, taking into account the characteristics of the pipeline leak, we propose a continuous random seismic source model and construct geological models to investigate the proposed method for locating underground pipeline leaks. Based on two dimensional (2D) viscoacoustic equations and the staggered grid finite-difference (FD) algorithm, the microseismic wave field generated by a leaking pipe is modeled. Cross-correlation analysis and the simulated annealing (SA) algorithm were utilized to obtain the time difference and the leak location. We also analyze and discuss the effect of the number of recorded traces, the survey layout, and the offset and interval of the traces on the accuracy of the estimated location. The preliminary results of the simulation and data field experiment indicate that (1) a continuous random source can realistically represent the leak microseismic wave field in a simulation using 2D visco-acoustic equations and a staggered grid FD algorithm. (2) The cross-correlation method is effective for calculating the time difference of the direct wave relative to the reference trace. However, outside the refraction blind zone, the accuracy of the time difference is reduced by the effects of the refracted wave. (3) The acquisition method of time difference based on the microseismic theory and SA algorithm has a great potential for locating leaks from underground pipelines from an array located on the ground surface. Keywords: Viscoacoustic finite-difference simulation; continuous random source; simulated annealing algorithm; pipeline leak location

The change of the inlet geometry of a centrifugal compressor stage and its influence on the compressor performance

NASA Astrophysics Data System (ADS)

Wang, Leilei; Yang, Ce; Zhao, Ben; Lao, Dazhong; Ma, Chaochen; Li, Du

2013-06-01

The impact on the compressor performance is important for designing the inlet pipe of the centrifugal compressor of a vehicle turbocharger with different inlet pipes. First, an experiment was performed to determine the compressor performance from three cases: a straight inlet pipe, a long bent inlet pipe and a short bent inlet pipe. Next, dynamic sensors were installed in key positions to collect the sign of the unsteady pressure of the centrifugal compressor. Combined with the results of numerical simulations, the total pressure distortion in the pipes, the pressure distributions on the blades and the pressure variability in the diffuser are studied in detail. The results can be summarized as follows: a bent pipe results in an inlet distortion to the compressor, which leads to performance degradation, and the effect is more apparent as the mass flow rate increases. The distortion induced by the bent inlet is not only influenced by the distance between the outlet of the bent section and the leading edge of the impeller but also by the impeller rotation. The flow fields in the centrifugal impeller and the diffuser are influenced by a coupling effect produced by the upstream inlet distortion and the downstream blocking effect from the volute tongue. If the inlet geometry is changed, the distributions and the fluctuation intensities of the static pressure on the main blade surface of the centrifugal impeller and in the diffuser are changed accordingly.

Splitting of turbulent spot in transitional pipe flow

NASA Astrophysics Data System (ADS)

Wu, Xiaohua; Moin, Parviz; Adrian, Ronald J.

2017-11-01

Recent study (Wu et al., PNAS, 1509451112, 2015) demonstrated the feasibility and accuracy of direct computation of the Osborne Reynolds' pipe transition problem without the unphysical, axially periodic boundary condition. Here we use this approach to study the splitting of turbulent spot in transitional pipe flow, a feature first discovered by E.R. Lindgren (Arkiv Fysik 15, 1959). It has been widely believed that spot splitting is a mysterious stochastic process that has general implications on the lifetime and sustainability of wall turbulence. We address the following two questions: (1) What is the dynamics of turbulent spot splitting in pipe transition? Specifically, we look into any possible connection between the instantaneous strain rate field and the spot splitting. (2) How does the passive scalar field behave during the process of pipe spot splitting. In this study, the turbulent spot is introduced at the inlet plane through a sixty degree wide numerical wedge within which fully-developed turbulent profiles are assigned over a short time interval; and the simulation Reynolds numbers are 2400 for a 500 radii long pipe, and 2300 for a 1000 radii long pipe, respectively. Numerical dye is tagged on the imposed turbulent spot at the inlet. Splitting of the imposed turbulent spot is detected very easily. Preliminary analysis of the DNS results seems to suggest that turbulent spot slitting can be easily understood based on instantaneous strain rate field, and such spot splitting may not be relevant in external flows such as the flat-plate boundary layer.

Investigation of structure in the modular light pipe component for LED automotive lamp

NASA Astrophysics Data System (ADS)

Chen, Hsi-Chao; Zhou, Yang; Huang, Chien-Sheng; Jhong, Wan-Ling; Cheng, Bo-Wei; Jhang, Jhe-Ming

2014-09-01

Light-Emitting Diodes (LEDs) have the advantages of small length, long lifetime, fast response time (μs), low voltage, good mechanical properties and environmental protection. Furthermore, LEDs could replace the halogen lamps to avoid the mercury pollution and economize the use of energy. Therefore, the LEDs could instead of the traditional lamp in the future and became an important light source. The proposal of this study was to investigate the effects of the structure and length of the reflector component for a LED automotive lamp. The novel LED automotive lamp was assembled by several different modularization columnar. The optimized design of the different structure and the length to the reflector was simulated by software TracePro. The design result must met the vehicle regulation of United Nations Economic Commission for Europe (UNECE) such as ECE-R19 etc. The structure of the light pipe could be designed by two steps structure. Then constitute the proper structure and choose different power LED to meet the luminous intensity of the vehicle regulation. The simulation result shows the proper structure and length has the best total luminous flux and a high luminous efficiency for the system. Also, the stray light could meet the vehicle regulation of ECE R19. Finally, the experimental result of the selected structure and length of the light pipe could match the simulation result above 80%.

Missouri River Emergent Sandbar Habitat Monitoring Plan - A Conceptual Framework for Adaptive Management

USGS Publications Warehouse

Sherfy, Mark H.; Stucker, Jennifer H.; Anteau, Michael J.

2009-01-01

Habitat conditions are one of the most important factors determining distribution and productivity of least terns (Sternula antillarum) and piping plovers (Charadrius melodus) in the upper Missouri River system (Ziewitz and others, 1992; Kruse and others, 2002). Habitat conditions are known to change within and among seasons in response to variation in river flows, weather conditions, and management actions targeted at providing for the needs of terns and plovers. Although these principles are generally agreed upon, there is little empirical information available on the quantity and quality of tern and plover habitats in this system, particularly with reference to the major life history events that must be supported (egg laying, incubation, and brood rearing). Habitat requirements for these events are composed of two major categories: nesting and foraging habitat. In the case of piping plovers, these two requirements must occur on the same area because plover chicks are constrained to foraging near nesting sites prior to fledging (Knetter and others, 2002; Haffner, 2005). In contrast, least terns chicks are fed by the adults, allowing food procurement for broods to occur outside the immediate nesting area; however, food resources must be close enough to nesting locations to minimize foraging time. The complexity and dynamics of the upper Missouri River system introduce considerable uncertainty into how best to manage tern and plover habitats, and how best to evaluate the effectiveness of this management. An extensive program of habitat monitoring will be needed to address this complexity and support the management of least terns and piping plovers under the Missouri River Recovery Program. These needs are being addressed, in part, through a program of habitat creation and management targeted at improving quality and quantity of habitats for terns and plovers. Given the momentum of these projects and their associated costs, it is imperative that the capacity be available to quantify changes in managed habitats for least terns and piping plovers, so that management effectiveness can be evaluated. Extremely high flows and flooding of the Missouri River in 1997 created and improved vast amounts of nesting habitat for least terns and piping plovers. Since 1998, there has been an apparent loss and/or degradation of habitat throughout the river system. However, during the same timeframe reservoir water levels have declined, exposing extensive piping plover breeding habitat. For example, 64 percent of adult piping plovers using the Missouri River in 2005 were observed on reservoir habitats, and 43 percent were observed on Lake Sakakawea (Threatened and Endangered Species Section, Omaha District, U.S. Army Corps of Engineers, unpub. data, 2006). Given the vast dynamics of this river and reservoir system, systemwide monitoring of habitat is clearly needed for the U.S. Army Corps of Engineers (USACE) to employ adaptive management (with respect to river operations) to provide most optimal conditions for the maintenance of breeding habitat of least terns and piping plovers. As a result of this need, the U.S. Geological Survey, in cooperation with the U.S. Army Corps of Engineers, began work on a habitat monitoring plan in 2005 as a conceptual framework for adaptive management.

Measurement of Gas-Liquid Two-Phase Flow in Micro-Pipes by a Capacitance Sensor

PubMed Central

Ji, Haifeng; Li, Huajun; Huang, Zhiyao; Wang, Baoliang; Li, Haiqing

2014-01-01

A capacitance measurement system is developed for the measurement of gas-liquid two-phase flow in glass micro-pipes with inner diameters of 3.96, 2.65 and 1.56 mm, respectively. As a typical flow regime in a micro-pipe two-phase flow system, slug flow is chosen for this investigation. A capacitance sensor is designed and a high-resolution and high-speed capacitance measurement circuit is used to measure the small capacitance signals based on the differential sampling method. The performance and feasibility of the capacitance method are investigated and discussed. The capacitance signal is analyzed, which can reflect the voidage variation of two-phase flow. The gas slug velocity is determined through a cross-correlation technique using two identical capacitance sensors. The simulation and experimental results show that the presented capacitance measurement system is successful. Research work also verifies that the capacitance sensor is an effective method for the measurement of gas liquid two-phase flow parameters in micro-pipes. PMID:25587879

Measurement of gas-liquid two-phase flow in micro-pipes by a capacitance sensor.

PubMed

Ji, Haifeng; Li, Huajun; Huang, Zhiyao; Wang, Baoliang; Li, Haiqing

2014-11-26

A capacitance measurement system is developed for the measurement of gas-liquid two-phase flow in glass micro-pipes with inner diameters of 3.96, 2.65 and 1.56 mm, respectively. As a typical flow regime in a micro-pipe two-phase flow system, slug flow is chosen for this investigation. A capacitance sensor is designed and a high-resolution and high-speed capacitance measurement circuit is used to measure the small capacitance signals based on the differential sampling method. The performance and feasibility of the capacitance method are investigated and discussed. The capacitance signal is analyzed, which can reflect the voidage variation of two-phase flow. The gas slug velocity is determined through a cross-correlation technique using two identical capacitance sensors. The simulation and experimental results show that the presented capacitance measurement system is successful. Research work also verifies that the capacitance sensor is an effective method for the measurement of gas liquid two-phase flow parameters in micro-pipes.

Reactivity Studies of Inconel 625 with Sodium, and Lunar Regolith Stimulant

NASA Technical Reports Server (NTRS)

Gillies, Donald; Salvail, Pat; Reid, Bob; Colebaugh, James; Easterling, Greg

2008-01-01

In the event of the need for nuclear power in exploration, high flux heat pipes will be needed for heat transfer from space nuclear reactors to various energy conversion devices, and to safely dissipate excess heat. Successful habitation will necessitate continuous operation of alkali metal filled heat pipes for 10 or-more years in a hostile environment with little maintenance. They must be chemical and creep resistant in the high vacuum of space (lunar), and they must operate reliably in low gravity conditions with intermittent high radiation fluxes. One candidate material for the heat pipe shell, namely Inconel 625, has been tested to determine its compatibility with liquid sodium. Any reactivity could manifest itself as a problem over the long time periods anticipated. In addition, possible reactions with the lunar regolith will take place, as will evaporation of selected elements at the external surfaces of the heat pipes, and so there is a need for extensive long-term testing under simulated lunar conditions.

Communication networks, soap films and vectors

NASA Astrophysics Data System (ADS)

Clark, R. C.

1981-01-01

The problem of constructing the least-cost network of connections between arbitrarily placed points is one that is common and which can be very important financially. The network may consist of motorways between towns, a grid of electric power lines, buried gas or oil pipe lines or telephone cables. Soap films trapped between parallel planes with vertical pins between them provide a 'shortest path' network and Isenberg (1975) has suggested that soap films of this sort be used to model communication networks. However soap films are unable to simulate the different costs of laying, say, a three-lane motorway instead of a two-lane one or of using a larger pipeline to take the flow from two smaller ones. Soap films, however, have considerable intrinsic interest. In the article the emphasis is on the use of soap films and communication networks as a practical means of illustrating the importance of vector and matrix methods in geometry. The power of vector methods is illustrated by the fact that given any soap film network the total length of the film can be written down by inspection if the vector positions of the pins are known. It is also possible to predict the boundaries at which 'catastrophes' occur and to decide which network has the least total length. In the field of communication networks a method is given of designing the minimum cost network linking, say, a number of oilwells, which produce at different rates to an outlet terminal.

Detection of Leaks in Water Distribution System using Non-Destructive Techniques

NASA Astrophysics Data System (ADS)

Aslam, H.; Kaur, M.; Sasi, S.; Mortula, Md M.; Yehia, S.; Ali, T.

2018-05-01

Water is scarce and needs to be conserved. A considerable amount of water which flows in the water distribution systems was found to be lost due to pipe leaks. Consequently, innovations in methods of pipe leakage detections for early recognition and repair of these leaks is vital to ensure minimum wastage of water in distribution systems. A major component of detection of pipe leaks is the ability to accurately locate the leak location in pipes through minimum invasion. Therefore, this paper studies the leak detection abilities of the three NDT’s: Ground Penetration Radar (GPR) and spectrometer and aims at determining whether these instruments are effective in identifying the leak. An experimental setup was constructed to simulate the underground conditions of water distribution systems. After analysing the experimental data, it was concluded that both the GPR and the spectrometer were effective in detecting leaks in the pipes. However, the results obtained from the spectrometer were not very differentiating in terms of observing the leaks in comparison to the results obtained from the GPR. In addition to this, it was concluded that both instruments could not be used if the water from the leaks had reached on the surface, resulting in surface ponding.

Physical disintegration of toilet papers in wastewater systems: experimental analysis and mathematical modeling.

PubMed

Eren, Beytullah; Karadagli, Fatih

2012-03-06

Physical disintegration of representative toilet papers was investigated in this study to assess their disintegration potential in sewer systems. Characterization of toilet papers from different parts of the world indicated two main categories as premium and average quality. Physical disintegration experiments were conducted with representative products from each category according to standard protocols with improvements. The experimental results were simulated by mathematical model to estimate best-fit values of disintegration rate coefficients and fractional distribution ratios. Our results from mathematical modeling and experimental work show that premium products release more amounts of small fibers and disintegrate more slowly than average ones. Comparison of the toilet papers with the tampon applicators studied previously indicates that premium quality toilet papers present significant potential to persist in sewer pipes. Comparison of turbulence level in our experimental setup with those of partial flow conditions in sewer pipes indicates that drains and small sewer pipes are critical sections where disintegration of toilet papers will be limited. For improvement, requirements for minimum pipe slopes may be increased to sustain transport and disintegration of flushable products in small pipes. In parallel, toilet papers can be improved to disintegrate rapidly in sewer systems, while they meet consumer expectations.

Use of a corrugated beam pipe as a passive deflector for bunch length measurements

NASA Astrophysics Data System (ADS)

Seok, Jimin; Chung, Moses; Kang, Heung-Sik; Min, Chang-Ki; Na, Donghyun

2018-02-01

We report the experimental demonstration of bunch length measurements using a corrugated metallic beam pipe as a passive deflector. The corrugated beam pipe has been adopted for reducing longitudinal chirping after the bunch compressors in several XFEL facilities worldwide. In the meantime, there have been attempts to measure the electron bunch's longitudinal current profile using the dipole wakefields generated in the corrugated pipe. Nevertheless, the bunch shape reconstructed from the nonlinearly deflected beam suffers from significant distortion, particularly near the head of the bunch. In this paper, we introduce an iterative process to improve the resolution of the bunch shape reconstruction. The astra and elegant simulations have been performed for pencil beam and cigar beam cases, in order to verify the effectiveness of the reconstruction process. To overcome the undesirable effects of transverse beam spreads, a measurement scheme involving both the corrugated beam pipe and the spectrometer magnet has been employed, both of which do not require a dedicated (and likely very expensive) rf system. A proof-of-principle experiment was carried out at Pohang Accelerator Laboratory (PAL) Injector Test Facility (ITF), and its results are discussed together with a comparison with the rf deflector measurement.

Visualization of Flow in Pressurizer Spray Line Piping and Estimation of Thermal Stress Fluctuation Caused by Swaying of Water Surface

NASA Astrophysics Data System (ADS)

Oumaya, Toru; Nakamura, Akira; Onojima, Daisuke; Takenaka, Nobuyuki

The pressurizer spray line of PWR plants cools reactor coolant by injecting water into pressurizer. Since the continuous spray flow rate during commercial operation of the plant is considered insufficient to fill the pipe completely, there is a concern that a water surface exists in the pipe and may periodically sway. In order to identify the flow regimes in spray line piping and assess their impact on pipe structure, a flow visualization experiment was conducted. In the experiment, air was used substituted for steam to simulate the gas phase of the pressurizer, and the flow instability causing swaying without condensation was investigated. With a full-scale mock-up made of acrylic, flow under room temperature and atmospheric pressure conditions was visualized, and possible flow regimes were identified based on the results of the experiment. Three representative patterns of swaying of water surface were assumed, and the range of thermal stress fluctuation, when the surface swayed instantaneously, was calculated. With the three patterns of swaying assumed based on the visualization experiment, it was confirmed that the thermal stress amplitude would not exceed the fatigue endurance limit prescribed in the Japanese Design and Construction Code.

Effects of Sulfate, Chloride, and Bicarbonate on Iron Stability in a PVC-U Drinking Pipe

PubMed Central

Wang, Jiaying; Tao, Tao; Yan, Hexiang

2017-01-01

In order to describe iron stability in plastic pipes and to ensure the drinking water security, the influence factors and rules for iron adsorption and release were studied, dependent on the Unplasticized poly (vinyl chloride) (PVC-U) drinking pipes employed in this research. In this paper, sulfate, chloride, and bicarbonate, as well as synthesized models, were chosen to investigate the iron stability on the inner wall of PVC-U drinking pipes. The existence of the three kinds of anions could significantly affect the process of iron adsorption, and a positive association was found between the level of anion concentration and the adsorption rate. However, the scaling formed on the inner surface of the pipes would be released into the water under certain conditions. The Larson Index (LI), used for a synthetic consideration of anion effects on iron stability, was selected to investigate the iron release under multi-factor conditions. Moreover, a well fitted linear model was established to gain a better understanding of iron release under multi-factor conditions. The simulation results demonstrated that the linear model was better fitted than the LI model for the prediction of iron release. PMID:28629192

Improvement of the thermal and mechanical flow characteristics in the exhaust system of piston engine through the use of ejection effect

NASA Astrophysics Data System (ADS)

Plotnikov, L. V.; Zhilkin, B. P.; Brodov, Yu M.

2017-11-01

The results of experimental research of gas dynamics and heat transfer in the exhaust process in piston internal combustion engines are presented. Studies were conducted on full-scale models of piston engine in the conditions of unsteady gas-dynamic (pulsating flows). Dependences of the instantaneous flow speed and the local heat transfer coefficient from the crankshaft rotation angle in the exhaust pipe are presented in the article. Also, the flow characteristics of the exhaust gases through the exhaust systems of various configurations are analyzed. It is shown that installation of the ejector in the exhaust system lead to a stabilization of the flow and allows to improve cleaning of the cylinder from exhaust gases and to optimize the thermal state of the exhaust pipes. Experimental studies were complemented by numerical simulation of the working process of the DM-21 diesel engine (production of “Ural diesel-motor plant”). The object of modeling was the eight-cylinder diesel with turbocharger. The simulation was performed taking into account the processes nonstationarity in the intake and exhaust pipes for the various configurations of exhaust systems (with and without ejector). Numerical simulation of the working process of diesel was performed in ACTUS software (ABB Turbo Systems). The simulation results confirmed the stabilization of the flow due to the use of the ejection effect in the exhaust system of a diesel engine. The use of ejection in the exhaust system of the DM-21 diesel leads to improvement of cleaning cylinders up to 10 %, reduces the specific fuel consumption on average by 1 %.

Comparison of numerical and experimental results of the flow in the U9 Kaplan turbine model

NASA Astrophysics Data System (ADS)

Petit, O.; Mulu, B.; Nilsson, H.; Cervantes, M.

2010-08-01

The present work compares simulations made using the OpenFOAM CFD code with experimental measurements of the flow in the U9 Kaplan turbine model. Comparisons of the velocity profiles in the spiral casing and in the draft tube are presented. The U9 Kaplan turbine prototype located in Porjus and its model, located in Älvkarleby, Sweden, have curved inlet pipes that lead the flow to the spiral casing. Nowadays, this curved pipe and its effect on the flow in the turbine is not taken into account when numerical simulations are performed at design stage. To study the impact of the inlet pipe curvature on the flow in the turbine, and to get a better overview of the flow of the whole system, measurements were made on the 1:3.1 model of the U9 turbine. Previously published measurements were taken at the inlet of the spiral casing and just before the guide vanes, using the laser Doppler anemometry (LDA) technique. In the draft tube, a number of velocity profiles were measured using the LDA techniques. The present work extends the experimental investigation with a horizontal section at the inlet of the draft tube. The experimental results are used to specify the inlet boundary condition for the numerical simulations in the draft tube, and to validate the computational results in both the spiral casing and the draft tube. The numerical simulations were realized using the standard k-e model and a block-structured hexahedral wall function mesh.

Resilience of microbial communities in a simulated drinking water distribution system subjected to disturbances: role of conditionally rare taxa and potential implications for antibiotic-resistant bacteria

EPA Science Inventory

Many US water utilities using chloramine as their secondary disinfectant have experienced nitrification episodes that detrimentally impact water quality in their distribution systems. A semi-closed pipe-loop chloraminated drinking water distribution system (DWDS) simulator was u...

Working parameters affecting earth-air heat exchanger (EAHE) system performance for passive cooling: A review

NASA Astrophysics Data System (ADS)

Darius, D.; Misaran, M. S.; Rahman, Md. M.; Ismail, M. A.; Amaludin, A.

2017-07-01

The study on the effect of the working parameters such as pipe material, pipe length, pipe diameter, depth of burial of the pipe, air flow rate and different types of soils on the thermal performance of earth-air heat exchanger (EAHE) systems is very crucial to ensure that thermal comfort can be achieved. In the past decade, researchers have performed studies to develop numerical models for analysis of EAHE systems. Until recently, two-dimensional models replaced the numerical models in the 1990s and in recent times, more advanced analysis using three-dimensional models, specifically the Computational Fluid Dynamics (CFD) simulation in the analysis of EAHE system. This paper reviews previous models used to analyse the EAHE system and working parameters that affects the earth-air heat exchanger (EAHE) thermal performance as of February 2017. Recent findings on the parameters affecting EAHE performance are also presented and discussed. As a conclusion, with the advent of CFD methods, investigational work have geared up to modelling and simulation work as it saves time and cost. Comprehension of the EAHE working parameters and its effect on system performance is largely established. However, the study on type of soil and its characteristics on the performance of EAHEs systems are surprisingly barren. Therefore, future studies should focus on the effect of soil characteristics such as moisture content, density of soil, and type of soil on the thermal performance of EAHEs system.

Gas propagation following a sudden loss of vacuum in a pipe cooled by He I and He II.

NASA Astrophysics Data System (ADS)

Garceau, N.; Guo, W.; Dodamead, T.

2017-12-01

Many cryogenic systems around the world are concerned with the sudden catastrophic loss of vacuum for cost, preventative damage, safety or other reasons. The experiments in this paper were designed to simulate the sudden vacuum break in the beam-line pipe of a liquid helium cooled superconducting particle accelerator. This paper expands previous research conducted at the National High Magnetic Field Laboratory and evaluates the differences between normal helium (He I) and superfluid helium (He II). For the experiments, a straight pipe and was evacuated and immersed in liquid helium at 4.2 K and below 2.17 K. Vacuum loss was simulated by opening a solenoid valve on a buffer tank filled nitrogen gas. Gas front arrival was observed by a temperature rise of the tube. Preliminary results suggested that the speed of the gas front through the experiment decreased exponentially along the tube for both normal liquid helium and super-fluid helium. The system was modified to a helical pipe system to increase propagation length. Testing and analysis on these two systems revealed there was minor difference between He I and He II despite the difference between the two distinct helium phases heat transfer mechanisms: convection vs thermal counterflow. Furthermore, the results indicated that the temperature of the tube wall above the LHe bath also plays a significant role in the initial front propagation. More systematic measurements are planned in with the helical tube system to further verify the results.

Insoluble Coatings for Stirling Engine Heat Pipe Condenser Surfaces

NASA Technical Reports Server (NTRS)

Dussinger, Peter M.; Lindemuth, James E.

1997-01-01

The principal objective of this Phase 2 SBIR program was to develop and demonstrate a practically insoluble coating for nickel-based superalloys for Stirling engine heat pipe applications. Specific technical objectives of the program were: (1) Determine the solubility corrosion rates for Nickel 200, Inconel 718, and Udimet 72OLI in a simulated Stirling engine heat pipe environment, (2) Develop coating processes and techniques for capillary groove and screen wick structures, (3) Evaluate the durability and solubility corrosion rates for capillary groove and screen wick structures coated with an insoluble coating in cylindrical heat pipes operating under Stirling engine conditions, and (4) Design and fabricate a coated full-scale, partial segment of the current Stirling engine heat pipe for the Stirling Space Power Convertor program. The work effort successfully demonstrated a two-step nickel aluminide coating process for groove wick structures and interior wall surfaces in contact with liquid metals; demonstrated a one-step nickel aluminide coating process for nickel screen wick structures; and developed and demonstrated a two-step aluminum-to-nickel aluminide coating process for nickel screen wick structures. In addition, the full-scale, partial segment was fabricated and the interior surfaces and wick structures were coated. The heat pipe was charged with sodium, processed, and scheduled to be life tested for up to ten years as a Phase 3 effort.

User's Manual for HPTAM: a Two-Dimensional Heat Pipe Transient Analysis Model, Including the Startup from a Frozen State

NASA Technical Reports Server (NTRS)

Tournier, Jean-Michel; El-Genk, Mohamed S.

1995-01-01

This report describes the user's manual for 'HPTAM,' a two-dimensional Heat Pipe Transient Analysis Model. HPTAM is described in detail in the UNM-ISNPS-3-1995 report which accompanies the present manual. The model offers a menu that lists a number of working fluids and wall and wick materials from which the user can choose. HPTAM is capable of simulating the startup of heat pipes from either a fully-thawed or frozen condition of the working fluid in the wick structure. The manual includes instructions for installing and running HPTAM on either a UNIX, MS-DOS or VMS operating system. Samples for input and output files are also provided to help the user with the code.

A new mechanism for periodic bursting of the recirculation region in the flow through a sudden expansion in a circular pipe

NASA Astrophysics Data System (ADS)

Lebon, Benoit; Nguyen, Minh Quan; Peixinho, Jorge; Shadloo, Mostafa Safdari; Hadjadj, Abdellah

2018-03-01

We report the results of a combined experimental and numerical study of specific finite-amplitude disturbances for transition to turbulence in the flow through a circular pipe with a sudden expansion. The critical amplitude thresholds for localized turbulent patch downstream of the expansion scale with the Reynolds number with a power law exponent of -2.3 for experiments and -2.8 for simulations. A new mechanism for the periodic bursting of the recirculation region is uncovered where the asymmetric recirculation flow develops a periodic dynamics: a secondary recirculation breaks the symmetry along the pipe wall and bursts into localized turbulence, which travels downstream and relaminarises. Flow visualizations show a simple flow pattern of three waves forming, growing, and bursting.

Mathematical Simulation of Drying Process of Fibrous Material

NASA Astrophysics Data System (ADS)

Blejchař, Tomáš; Raška, Jiří; Jablonská, Jana

2018-06-01

The article describes mathematical simulation of flowing air through porous zone and water vaporisation from mentioned porous area which actually represents dried fibrous material - cotton towel. Simulation is based on finite volume method. Wet towel is placed in pipe and hot air flow through the towel. Water from towel is evaporated. Simulation of airflow through porous element is described first. Eulerian multiphase model is then used for simulation of water vaporisation from porous medium. Results of simulation are compared with experiment. Ansys Fluent 13.0 was used for calculation.

Transfer of fat-soluble pesticides from contaminated feed to poultry tissues and eggs.

PubMed

MacLachlan, D J

2008-05-01

1. Implementation of Good Manufacturing Practice and HACCP (Hazard Analysis Critical Control Points) in the production of poultry feed requires efficient tools for profiling risks associated with pesticide use in the production of crops for feed. 2. This paper describes a simple model that may be of use in the first tiers of risk profiling of feeds. 3. The model adequately reproduced the pattern of residues in fat and eggs of laying hens dosed with a selection of lipophilic pesticides that may be used in the production of crops for poultry feeds: deltamethrin, diflubenzuron, fipronil, lindane, piperonyl butoxide and spinosad. 4. Simulations suggest results derived from studies on laying chickens can be extrapolated to other laying birds. 5. Poultry meat production systems focus on maximising growth of birds giving rise to significant potential for dilution of residues that transfer to fat from feed. 6. Simulations of residues in fat of chickens, ducks, geese and turkeys exposed to a lipophilic pesticide with an elimination half-life of one day at 10 mg/kg body weight/d from hatching to typical market ages suggest residues in fat that are highest in turkeys > chickens > geese > ducks. 7. The model is of use in interpreting published dosing studies and predicting likely residues in birds at times after last exposure/dosing.

Simulation of air velocity in a vertical perforated air distributor

NASA Astrophysics Data System (ADS)

Ngu, T. N. W.; Chu, C. M.; Janaun, J. A.

2016-06-01

Perforated pipes are utilized to divide a fluid flow into several smaller streams. Uniform flow distribution requirement is of great concern in engineering applications because it has significant influence on the performance of fluidic devices. For industrial applications, it is crucial to provide a uniform velocity distribution through orifices. In this research, flow distribution patterns of a closed-end multiple outlet pipe standing vertically for air delivery in the horizontal direction was simulated. Computational Fluid Dynamics (CFD), a tool of research for enhancing and understanding design was used as the simulator and the drawing software SolidWorks was used for geometry setup. The main purpose of this work is to establish the influence of size of orifices, intervals between outlets, and the length of tube in order to attain uniformity of exit flows through a multi outlet perforated tube. However, due to the gravitational effect, the compactness of paddy increases gradually from top to bottom of dryer, uniform flow pattern was aimed for top orifices and larger flow for bottom orifices.

GPM Avionics Module Heat Pipes Design and Performance Test Results

NASA Technical Reports Server (NTRS)

Ottenstein, Laura; DeChristopher, Mike

2011-01-01

The Global Precipitation Measurement (GPM) mission is an international network of satellites that provide the next-generation global observations of rain and snow. The GPM core satellite carries an advanced radar / radiometer system to measure precipitation from space and serve as a reference standard to unify precipitation measurements from a constellation of research and operational satellites. Through improved measurements of precipitation globally, the GPM mission will help to advance our understanding of Earth's water and energy cycle, improve forecasting of extreme events that cause natural hazards and disasters, and extend current capabilities in using accurate and timely information of precipitation to directly benefit society. The avionics module on the core satellite contains a number of electronics boxes which are cooled by a network of aluminum/ammonia heat pipes and a honeycomb radiator which contains thirteen embedded aluminum/ammonia heat pipes. All heat pipes were individually tested by the vendor (Advanced Cooling Technologies, Inc.) prior to delivery. Following delivery to NASA, the flight avionics radiator and the flight spare transport heat pipes were mounted to flight-like test structure and a system level thermal vacuum test was performed. This test, which used simulators in place of all electronics boxes, was done to verify the operation of the thermal control system as a whole. This presentation will discuss the design of the avionics module heat pipes, and then discuss performance tests results for the individual heat pipes prior to delivery and for the system level thermal vacuum test. All heat pipes met their performance requirements. However, it was found that the power was too low in some instances to start all of the smaller radiator spreader heat pipes when they were tested in a reflux configuration (which is the nominal test configuration). Although this lowered the efficiency of the radiator somewhat, it did not impact the operating temperatures of the electronics boxes.

Development of the monitoring system to detect the piping thickness reduction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, N. Y.; Ryu, K. H.; Oh, Y. J.

2006-07-01

As nuclear piping becomes aging, secondary piping which was considered safe, undergo thickness reduction problem these days. After some accidents caused by Flow Accelerated Corrosion (FAC), guidelines and recommendations for the thinned pipe management were issued, and thus need for monitoring increases. Through thinned pipe management program, monitoring activities based on the various analyses and the case study of other plants also increases. As the monitoring points increase, time needs to cover the recommended inspection area becomes increasing, while the time given to inspect the piping during overhaul becomes shortened. Existing Ultrasonic Technique (UT) can cover small area in amore » given time. Moreover, it cannot be applied to a complex geometry piping or a certain location like welded part. In this paper, we suggested Switching Direct Current Potential Drop (S-DCPD) method by which we can narrow down the FAC-susceptible area. To apply DCPD, we developed both resistance model and Finite Element Method (FEM) model to predict the DCPD feasibility. We tested elbow specimen to compare DCPD monitoring results with UT results to identify consistency. For the validation test, we designed simulation loop. To determine the text condition, we analyzed environmental parameters and introduced applicable wearing rate model. To obtain the model parameters, we developed electrodes and analyzed velocity profile in the test loop using CFX code. Based on the prediction model and prototype testing results, we are planning to perform validation test to identify applicability of S-DCPD in the NPP environment. Validation text plan will be described as a future work. (authors)« less

Computation of turbulent pipe and duct flow using third order upwind scheme

NASA Technical Reports Server (NTRS)

Kawamura, T.

1986-01-01

The fully developed turbulence in a circular pipe and in a square duct is simulated directly without using turbulence models in the Navier-Stokes equations. The utilized method employs a third-order upwind scheme for the approximation to the nonlinear term and the second-order Adams-Bashforth method for the time derivative in the Navier-Stokes equation. The computational results appear to capture the large-scale turbulent structures at least qualitatively. The significance of the artificial viscosity inherent in the present scheme is discussed.

Taylor dispersion of colloidal particles in narrow channels

NASA Astrophysics Data System (ADS)

Sané, Jimaan; Padding, Johan T.; Louis, Ard A.

2015-09-01

We use a mesoscopic particle-based simulation technique to study the classic convection-diffusion problem of Taylor dispersion for colloidal discs in confined flow. When the disc diameter becomes non-negligible compared to the diameter of the pipe, there are important corrections to the original Taylor picture. For example, the colloids can flow more rapidly than the underlying fluid, and their Taylor dispersion coefficient is decreased. For narrow pipes, there are also further hydrodynamic wall effects. The long-time tails in the velocity autocorrelation functions are altered by the Poiseuille flow.

Bringing simulation to engineers in the field: a Web 2.0 approach.

PubMed

Haines, Robert; Khan, Kashif; Brooke, John

2009-07-13

Field engineers working on water distribution systems have to implement day-to-day operational decisions. Since pipe networks are highly interconnected, the effects of such decisions are correlated with hydraulic and water quality conditions elsewhere in the network. This makes the provision of predictive decision support tools (DSTs) for field engineers critical to optimizing the engineering work on the network. We describe how we created DSTs to run on lightweight mobile devices by using the Web 2.0 technique known as Software as a Service. We designed our system following the architectural style of representational state transfer. The system not only displays static geographical information system data for pipe networks, but also dynamic information and prediction of network state, by invoking and displaying the results of simulations running on more powerful remote resources.

Numerical Analysis of Pelton Nozzle Jet Flow Behavior Considering Elbow Pipe

NASA Astrophysics Data System (ADS)

Chongji, Zeng; Yexiang, Xiao; Wei, Xu; Tao, Wu; Jin, Zhang; Zhengwei, Wang; Yongyao, Luo

2016-11-01

In Pelton turbine, the dispersion of cylindrical jet have a great influence on the energy interaction of jet and buckets. This paper simulated the internal flow of nozzle and the downstream free jet flow at 3 different needle strokes. The nozzle model consists of the elbow pipe and the needle rod which supported by 4 ribs. Homogenous model and SST k-ω model were adopted to simulate the unsteady two-phase jet flow. The development of free flow, including a contraction process followed by an expansion process, was analysed detailed as well as the influence of the nozzle geometry on the jet flow pattern. The increase of nozzle opening results in a more dispersion jet, which means a higher hydraulic loss. Upstream bend and ribs induce the secondary flow in the jet and decrease the jet concentration.

Autonomous Cryogenics Loading Operations Simulation Software: Knowledgebase Autonomous Test Engineer

NASA Technical Reports Server (NTRS)

Wehner, Walter S., Jr.

2013-01-01

Working on the ACLO (Autonomous Cryogenics Loading Operations) project I have had the opportunity to add functionality to the physics simulation software known as KATE (Knowledgebase Autonomous Test Engineer), create a new application allowing WYSIWYG (what-you-see-is-what-you-get) creation of KATE schematic files and begin a preliminary design and implementation of a new subsystem that will provide vision services on the IHM (Integrated Health Management) bus. The functionality I added to KATE over the past few months includes a dynamic visual representation of the fluid height in a pipe based on number of gallons of fluid in the pipe and implementing the IHM bus connection within KATE. I also fixed a broken feature in the system called the Browser Display, implemented many bug fixes and made changes to the GUI (Graphical User Interface).

Transverse Kick Analysis of SSR1 Due to Possible Geometrical Variations in Fabrication

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yakovlev, V.P.; /Fermilab; Awida, M.H.

2012-05-01

Due to fabrication tolerance, it is expected that some geometrical variations could happen to the SSR1 cavities of Project X, like small shifts in the transverse direction of the beam pipe or the spoke. It is necessary to evaluate the resultant transverse kick due to these geometrical variations, in order to make sure that they are within the limits of the correctors in the solenoids. In this paper, we report the transverse kick values for various fabrications errors and the sensitivity of the beam to these errors. Transverse kick that could happen in SSR1 cavities due to geometrical variations ofmore » the fabricated cavities from the designed geometry has been analysed and evaluated. From fabrication experience, three kinds of variations were under investigation concerning the alignment of both the beam pipe and spoke with respect to the beam axis. Simulation study has been carried out implementing these variations in the simulation model. CMM measurements of five fabricated SSR1 cavities were carried out to investigate the amount of physical misalignments of the beam pipe and spoke. Bead-pull measurements were also conducted to evaluate the transverse kick values in the fabricated cavities. Simulation and measurements are relatively in good agreement. Maximum kick in the fabricated cavities is within 154 keV that would induce about 1.12 mrad beam deviation, which could be definitely corrected with the 10 mrad specified correctors of Project X.« less

Dynamic simulation of relief line during loss of insulation vacuum of the ITER cryoline

NASA Astrophysics Data System (ADS)

Badgujar, S.; Kosek, J.; Grillot, D.; Forgeas, A.; Sarkar, B.; Shah, N.; Choukekar, K.; Chang, H.-S.

2017-12-01

The ITER cryoline (CL) system consists of 37 types of vacuum jacketed transfer lines which forms a complex structured network with a total length of about 5 km, spread inside the Tokamak building, on a dedicated plant bridge and in the Cryoplant building/area. One of them, the low pressure relief line (RL) recovers helium discharged from process safety relief valves of the different cryogenic users and is sent it back to the Cryoplant via heater and recovery system. The process pipe diameters of the RL vary from DN 50 to DN 200 and the length is more than 1500 m. Loss of insulation vacuum (LIV) of a CL is one of the worst scenarios apart from LIV in Auxiliary Cold Boxes (ACBs). The Torus and Cryostat CL is chosen to simulate the virtual LIV and to study the anticipated behavior of the RL. Both helium LIV (LIV due to leak in helium pipe) and air LIV (LIV due to air ingress in outer vacuum jacket of the cryoline) with and without fire) have been simulated during this study. After the brief description of the CL system, the paper will describe the EcosimPro® model prepared for the dynamic study. The paper will also describe the results like minimum temperature of RL, mass flow and maximum pressure in the RL which are essentially used to choose the type and location of safety relief devices to protect the CL process pipes.

The comparative analysis of heat transfer efficiency in the conditions of formation of ash deposits in the boiler furnaces, with taking into account the crystallization of slag during combustion of coal and water-coal fuel

NASA Astrophysics Data System (ADS)

Salomatov, V. V.; Kuznetsov, G. V.; Syrodoy, S. V.

2017-11-01

The results of the numerical simulation of heat transfer from the combustion products of coal and coal-water fuels (CWF) to the internal environment. The mathematical simulation has been carried out on the sample of the pipe surfaces of the combustion chamber of the boiler unit. The change in the characteristics of heat transfer (change of thermochemical characteristics) in the conditions of formation of the ash deposits have been taken into account. According to the results of the numerical simulation, the comparative analysis of the efficiency of heat transfer has been carried out from the furnace environment to the inside pipe coolant (water, air, or water vapor) from the combustion of coal and coal-water fuels. It has been established that, in the initial period of the boiler unit operation during coal fuel combustion the efficiency of heat transfer from the combustion products of the internal environment is higher than when using CWF. The efficiency of heat transfer in CWF combustion conditions is more at large times (τ≥1.5 hours) of the boiler unit. A significant decrease in heat flux from the combustion products to the inside pipe coolant in the case of coal combustion compared to CWF has been found. It has been proved that this is due primarily to the fact that massive and strong ash deposits are formed during coal combustion.

EFFECT OF SIMULATED SULFURIC ACID RAIN ON THE CHEMISTRY OF A SULFATE-ADSORBING FOREST SOIL

EPA Science Inventory

Simulated H2SO4 rain (pH 3.0, 3.5, 4.0) or control rain (pH 5.6) was applied for 3.5 yr to large lysimeter boxes containing a sulfate-adsorbing forest soil and either red alder (Alnus rubra) or sugar maple (Acer saccharum) seedlings. After removal of the plants and the litter lay...

Defect Detection and Segmentation Framework for Remote Field Eddy Current Sensor Data

PubMed Central

2017-01-01

Remote-Field Eddy-Current (RFEC) technology is often used as a Non-Destructive Evaluation (NDE) method to prevent water pipe failures. By analyzing the RFEC data, it is possible to quantify the corrosion present in pipes. Quantifying the corrosion involves detecting defects and extracting their depth and shape. For large sections of pipelines, this can be extremely time-consuming if performed manually. Automated approaches are therefore well motivated. In this article, we propose an automated framework to locate and segment defects in individual pipe segments, starting from raw RFEC measurements taken over large pipelines. The framework relies on a novel feature to robustly detect these defects and a segmentation algorithm applied to the deconvolved RFEC signal. The framework is evaluated using both simulated and real datasets, demonstrating its ability to efficiently segment the shape of corrosion defects. PMID:28984823

Residual stress determination in an overlay dissimilar welded pipe by neutron diffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woo, Wan Chuck; Em, Vyacheslav; Hubbard, Camden R

2011-01-01

Residual stresses were determined through the thickness of a dissimilar weld overlay pipe using neutron diffraction. The specimen has a complex joining structure consisting of a ferritic steel (SA508), austenitic steel (F316L), Ni-based consumable (Alloy 182), and overlay of Ni-base superalloy (Alloy 52M). It simulates pressurized nozzle components, which have been a critical issue under the severe crack condition of nuclear power reactors. Two neutron diffractometers with different spatial resolutions have been utilized on the identical specimen for comparison. The macroscopic 'stress-free' lattice spacing (d{sub o}) was also obtained from both using a 2-mm width comb-like coupon. The results showmore » significant changes in residual stresses from tension (300-400 MPa) to compression (-600 MPa) through the thickness of the dissimilar weld overlay pipe specimen.« less

Exponential Boundary Observers for Pressurized Water Pipe

NASA Astrophysics Data System (ADS)

Hermine Som, Idellette Judith; Cocquempot, Vincent; Aitouche, Abdel

2015-11-01

This paper deals with state estimation on a pressurized water pipe modeled by nonlinear coupled distributed hyperbolic equations for non-conservative laws with three known boundary measures. Our objective is to estimate the fourth boundary variable, which will be useful for leakage detection. Two approaches are studied. Firstly, the distributed hyperbolic equations are discretized through a finite-difference scheme. By using the Lipschitz property of the nonlinear term and a Lyapunov function, the exponential stability of the estimation error is proven by solving Linear Matrix Inequalities (LMIs). Secondly, the distributed hyperbolic system is preserved for state estimation. After state transformations, a Luenberger-like PDE boundary observer based on backstepping mathematical tools is proposed. An exponential Lyapunov function is used to prove the stability of the resulted estimation error. The performance of the two observers are shown on a water pipe prototype simulated example.

Defect Detection and Segmentation Framework for Remote Field Eddy Current Sensor Data.

PubMed

Falque, Raphael; Vidal-Calleja, Teresa; Miro, Jaime Valls

2017-10-06

Remote-Field Eddy-Current (RFEC) technology is often used as a Non-Destructive Evaluation (NDE) method to prevent water pipe failures. By analyzing the RFEC data, it is possible to quantify the corrosion present in pipes. Quantifying the corrosion involves detecting defects and extracting their depth and shape. For large sections of pipelines, this can be extremely time-consuming if performed manually. Automated approaches are therefore well motivated. In this article, we propose an automated framework to locate and segment defects in individual pipe segments, starting from raw RFEC measurements taken over large pipelines. The framework relies on a novel feature to robustly detect these defects and a segmentation algorithm applied to the deconvolved RFEC signal. The framework is evaluated using both simulated and real datasets, demonstrating its ability to efficiently segment the shape of corrosion defects.

First Annual Progress Report on Transmission of Information by Acoustic Communication along Metal Pathways in Nuclear Facilities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heifetz, A.; Bakhtiari, S.; Huang, X.

The objective of this project is to develop and demonstrate methods for transmission of information in nuclear facilities by acoustic means along existing in-place metal piping infrastructure. Pipes are omnipresent in a nuclear facility, and penetrate enclosures and partitions, such as the containment building wall. In the envisioned acoustic communication (AC) system, packets of information will be transmitted as guided acoustic waves along pipes. Performance of AC hardware and network protocols for efficient and secure communications under development in this project will be eventually evaluated in a representative nuclear power plant environment. Research efforts in the first year of thismore » project have been focused on identification of appropriate transducers, and evaluation of their performance for information transmission along nuclear-grade metallic pipes. COMSOL computer simulations were performed to study acoustic wave generation, propagation, and attenuation on pipes. An experimental benchtop system was used to evaluate signal attenuation and spectral dispersion using piezo-electric transducers (PZTs) and electromagnetic acoustic transducers (EMATs). Communication protocols under evaluation consisted on-off keying (OOK) signal modulation, in particular amplitude shift keying (ASK) and phase shift keying (PSK). Tradeoffs between signal power and communication data rate were considered for ASK and PSK coding schemes.« less

Numerical analysis of flow resistance and heat transfer in the transitional regime of pipe flow with twisted-tape turbulators

NASA Astrophysics Data System (ADS)

Rossi, R.; Cattani, L.; Mocerino, A.; Bozzoli, F.; Rainieri, S.; Caminati, R.; Pagliarini, G.

2017-11-01

In this paper, we present the numerical analysis of the fully developed ow and heat transfer in pipes equipped with twisted-tape inserts in the laminar to transitional flow regime. The flow Reynolds number ranges from 210 to 3100 based on the pipe diameter, whereas the Prandtl number of the working fluid, a 40% mixture of water and ethylene glycol, is about 45 at the average film temperature. The numerical study is carried out via Scale Adaptive Simulations (SAS) where the k-ω SST model is employed for turbulence modeling. Using SAS and low-dissipation discretization schemes, the present study shows that it is possible to capture the transition from the laminar regime to the pulsating or pseudo-laminar flow regime induced by the twisted-tape at low Reynolds numbers, as well as the transition to moderate turbulent regime at the higher, yet non-turbulent for smooth pipes, range of Reynolds numbers. Numerical results, validated against experiments performed in a dedicated test rig, show very good agreement with measured data and an increase of the friction factor and Nusselt number in the range of 4 to 7 times and 6 to 15 times, respectively, of the values for an empty pipe.

Monitoring underground water leakage pattern by ground penetrating radar (GPR) using 800 MHz antenna frequency

NASA Astrophysics Data System (ADS)

Amran, T. S. T.; Ismail, M. P.; Ahmad, M. R.; Amin, M. S. M.; Ismail, M. A.; Sani, S.; Masenwat, N. A.; Basri, N. S. M.

2018-01-01

Water is the most treasure natural resources, however, a huge amount of water are lost during its distribution that leads to water leakage problem. The leaks meant the waste of money and created more economic loss to treat and fix the damaged pipe. Researchers and engineers have put tremendous attempts and effort, to solve the water leakage problem especially in water leakage of buried pipeline. An advanced technology of ground penetrating radar (GPR) has been established as one of the non-destructive testing (NDT) method to detect the underground water pipe leaking. This paper focuses on the ability of GPR in water utility field especially on detection of water leaks in the underground pipeline distribution. A series of laboratory experiments were carried out using 800-MHz antenna, where the performance of GPR on detecting underground pipeline and locating water leakage was investigated and validated. A prototype to recreate water-leaking system was constructed using a 4-inch PVC pipe. Different diameter of holes, i.e. ¼ inch, ½ inch, and ¾ inch, were drilled into the pipe to simulate the water leaking. The PVC pipe was buried at the depth of 60 cm into the test bed that was filled with dry sand. 15 litres of water was injected into the PVC pipe. The water leakage patterns in term of radargram data were gathered. The effectiveness of the GPR in locating the underground water leakage was ascertained, after the results were collected and verified.

Numerical study of the influence of geometrical characteristics of a vertical helical coil on a bubbly flow

NASA Astrophysics Data System (ADS)

Saffari, H.; Moosavi, R.

2014-11-01

In this article, turbulent single-phase and two-phase (air-water) bubbly fluid flows in a vertical helical coil are analyzed by using computational fluid dynamics (CFD). The effects of the pipe diameter, coil diameter, coil pitch, Reynolds number, and void fraction on the pressure loss, friction coefficient, and flow characteristics are investigated. The Eulerian-Eulerian model is used in this work to simulate the two-phase fluid flow. Three-dimensional governing equations of continuity, momentum, and energy are solved by using the finite volume method. The k- ɛ turbulence model is used to calculate turbulence fluctuations. The SIMPLE algorithm is employed to solve the velocity and pressure fields. Due to the effect of a secondary force in helical pipes, the friction coefficient is found to be higher in helical pipes than in straight pipes. The friction coefficient increases with an increase in the curvature, pipe diameter, and coil pitch and decreases with an increase in the coil diameter and void fraction. The close correlation between the numerical results obtained in this study and the numerical and empirical results of other researchers confirm the accuracy of the applied method. For void fractions up to 0.1, the numerical results indicate that the friction coefficient increases with increasing the pipe diameter and keeping the coil pitch and diameter constant and decreases with increasing the coil diameter. Finally, with an increase in the Reynolds number, the friction coefficient decreases, while the void fraction increases.

Comparison of Two-Phase Pipe Flow in OpenFOAM with a Mechanistic Model

NASA Astrophysics Data System (ADS)

Shuard, Adrian M.; Mahmud, Hisham B.; King, Andrew J.

2016-03-01

Two-phase pipe flow is a common occurrence in many industrial applications such as power generation and oil and gas transportation. Accurate prediction of liquid holdup and pressure drop is of vast importance to ensure effective design and operation of fluid transport systems. In this paper, a Computational Fluid Dynamics (CFD) study of a two-phase flow of air and water is performed using OpenFOAM. The two-phase solver, interFoam is used to identify flow patterns and generate values of liquid holdup and pressure drop, which are compared to results obtained from a two-phase mechanistic model developed by Petalas and Aziz (2002). A total of 60 simulations have been performed at three separate pipe inclinations of 0°, +10° and -10° respectively. A three dimensional, 0.052m diameter pipe of 4m length is used with the Shear Stress Transport (SST) k - ɷ turbulence model to solve the turbulent mixtures of air and water. Results show that the flow pattern behaviour and numerical values of liquid holdup and pressure drop compare reasonably well to the mechanistic model.

Recent developments in guided wave travel time tomography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zon, Tim van; Volker, Arno

The concept of predictive maintenance using permanent sensors that monitor the integrity of an installation is an interesting addition to the current method of periodic inspections. Guided wave tomography had been developed to create a map of the wall thickness using the travel times of guided waves. It can be used for both monitoring and for inspection of pipe-segments that are difficult to access, for instance at the location of pipe-supports. An important outcome of the tomography is the minimum remaining wall thickness, as this is critical in the scheduling of a replacement of the pipe-segment. In order to improvemore » the sizing accuracy we have improved the tomography scheme. A number of major improvements have been realized allowing to extend the application envelope to pipes with a larger wall thickness and to larger distances between the transducer rings. Simulation results indicate that the sizing accuracy has improved and that is now possible to have a spacing of 8 meter between the source-ring and the receiver-ring. Additionally a reduction of the number of sensors required might be possible as well.« less

Numerical Investigation of Temperature Distribution in an Eroded Bend Pipe and Prediction of Erosion Reduced Thickness

PubMed Central

Zhu, Hongjun; Feng, Guang; Wang, Qijun

2014-01-01

Accurate prediction of erosion thickness is essential for pipe engineering. The objective of the present paper is to study the temperature distribution in an eroded bend pipe and find a new method to predict the erosion reduced thickness. Computational fluid dynamic (CFD) simulations with FLUENT software are carried out to investigate the temperature field. And effects of oil inlet rate, oil inlet temperature, and erosion reduced thickness are examined. The presence of erosion pit brings about the obvious fluctuation of temperature drop along the extrados of bend. And the minimum temperature drop presents at the most severe erosion point. Small inlet temperature or large inlet velocity can lead to small temperature drop, while shallow erosion pit causes great temperature drop. The dimensionless minimum temperature drop is analyzed and the fitting formula is obtained. Using the formula we can calculate the erosion reduced thickness, which is only needed to monitor the outer surface temperature of bend pipe. This new method can provide useful guidance for pipeline monitoring and replacement. PMID:24719576

Effect of Torsion on the Friction Factor of Helical Pipe Flow

NASA Astrophysics Data System (ADS)

Kumer Datta, Anup; Yanase, Shinichiro; Hayamizu, Yasutaka; Kouchi, Toshinori; Nagata, Yasunori; Yamamoto, Kyoji

2017-06-01

Three-dimensional direct numerical simulations of a viscous incompressible fluid flow through a helical pipe with a circular cross section were conducted for three Reynolds numbers, Re (= 80, 300, and 1000), and two nondimensional curvatures, δ (= 0.1 and 0.05), over a wide range of torsion parameters, β (= nondimensional torsion/√{2δ } ), from 0.02 to 2.8. Well-developed axially invariant regions were obtained where the friction factors were calculated, in good agreement with the experimental data obtained by Yamamoto et al. [https://doi.org/10.1016/0169-5983(95)00022-6, Fluid Dyn. Res. 16, 237 (1995)]. It was found that the friction factor sharply increases as β increases from zero, then decreases after taking a maximum, and finally slowly approaches that of a straight pipe when β tends to infinity. It is interesting that a peak of the friction factor exists in the region 0.2 ≤ β ≤ 0.3 for all the Reynolds numbers and curvatures studied in the present paper, which manifests the importance of the torsion parameter in helical pipe flow.

Pentzien lays diagonal cross of Potomac for Columbia gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klinger, O.

1976-05-01

One of the most unusual pipeline river crossings was completed last fall by Pentzien, Inc., for Columbia LNG Corp. on the Potomac River at Bryans Road, MD, 22 miles south of Washington, DC. Part of a line delivering regasified Algerian LNG to Virginia and Pennsylvania, this crossing would have been only 7896 ft straight across the river; however, to obtaining necessary country authorization without excessively delaying the project, the line was laid diagonally 19,500 ft across the river at a cost about two-thirds more than for a straight-line crossing. The concrete-coated 36-in.-diam pipe for the project was so heavy thatmore » each transport truck could handle only a single 40-ft length at a time. Laser beams on each side of the river were used to guide both the dredging and pipelaying operations.« less

Research Technology

NASA Image and Video Library

1998-01-01

Engineers at Marshall Space Flight Center (MSFC) in Huntsville, Alabama, are working with industry partners to develop a new generation of more cost-efficient space vehicles. Lightweight fuel tanks and components under development will be the critical elements in tomorrow's reusable launch vehicles and will tremendously curb the costs of getting to space. In this photo, Tom DeLay, a materials processes engineer for MSFC, uses a new graphite epoxy technology to create lightweight cryogenic fuel lines for futuristic reusable launch vehicles. He is wrapping a water-soluble mandrel, or mold, with a graphite fabric coated with an epoxy resin. Once wrapped, the pipe will be vacuum-bagged and autoclave-cured. The disposable mold will be removed to reveal a thin-walled fuel line. In addition to being much lighter and stronger than metal, this material won't expand or contract as much in the extreme temperatures encountered by launch vehicles.

Experimental and numerical study of latent heat thermal energy storage systems assisted by heat pipes for concentrated solar power application

NASA Astrophysics Data System (ADS)

Tiari, Saeed

A desirable feature of concentrated solar power (CSP) with integrated thermal energy storage (TES) unit is to provide electricity in a dispatchable manner during cloud transient and non-daylight hours. Latent heat thermal energy storage (LHTES) offers many advantages such as higher energy storage density, wider range of operating temperature and nearly isothermal heat transfer relative to sensible heat thermal energy storage (SHTES), which is the current standard for trough and tower CSP systems. Despite the advantages mentioned above, LHTES systems performance is often limited by low thermal conductivity of commonly used, low cost phase change materials (PCMs). Research and development of passive heat transfer devices, such as heat pipes (HPs) to enhance the heat transfer in the PCM has received considerable attention. Due to its high effective thermal conductivity, heat pipe can transport large amounts of heat with relatively small temperature difference. The objective of this research is to study the charging and discharging processes of heat pipe-assisted LHTES systems using computational fluid dynamics (CFD) and experimental testing to develop a method for more efficient energy storage system design. The results revealed that the heat pipe network configurations and the quantities of heat pipes integrated in a thermal energy storage system have a profound effect on the thermal response of the system. The optimal placement of heat pipes in the system can significantly enhance the thermal performance. It was also found that the inclusion of natural convection heat transfer in the CFD simulation of the system is necessary to have a realistic prediction of a latent heat thermal storage system performance. In addition, the effects of geometrical features and quantity of fins attached to the HPs have been studied.

Comparison of superhydrophobic drag reduction between turbulent pipe and channel flows

NASA Astrophysics Data System (ADS)

Im, Hyung Jae; Lee, Jae Hwa

2017-09-01

It has been known over several decades that canonical wall-bounded internal flows of a pipe and channel share flow similarities, in particular, close to the wall due to the negligible curvature effect. In the present study, direct numerical simulations of fully developed turbulent pipe and channel flows are performed to investigate the influence of the superhydrophobic surfaces (SHSs) on the turbulence dynamics and the resultant drag reduction (DR) of the flows under similar conditions. SHSs at the wall are modeled in spanwise-alternating longitudinal regions with a boundary with no-slip and shear-free conditions, and the two parameters of the spanwise periodicity (P/δ) and SHS fraction (GF) within a pitch are considered. It is shown, in agreement with previous investigations in channels, that the turbulent drag for the pipe and channel flows over SHSs is continuously decreased with increases in P/δ and GF. However, the DR rate in the pipe flows is greater than that in the channel flows with an accompanying reduction of the Reynolds stress. The enhanced performance of the DR for the pipe flow is attributed to the increased streamwise slip and weakened Reynolds shear stress contributions. In addition, a mathematical analysis of the spanwise mean vorticity equation suggests that the presence of a strong secondary flow due to the increased spanwise slip of the pipe flows makes a greater negative contribution of advective vorticity transport than the channel flows, resulting in a higher DR value. Finally, an inspection of the origin of the mean secondary flow in turbulent flows over SHSs based on the spatial gradients of the turbulent kinetic energy demonstrates that the secondary flow is both driven and sustained by spatial gradients in the Reynolds stress components, i.e., Prandtl's secondary flow of the second kind.

Numerical investigation of Dean vortices in a curved pipe

NASA Astrophysics Data System (ADS)

Bernad, S. I.; Totorean, A.; Bosioc, A.; Stanciu, R.; Bernad, E. S.

2013-10-01

This study is devoted to the three-dimensional numerical simulation of developing secondary flows of Newtonian fluid through a curved circular duct. The numerical simulations produced for different Dean numbers show clearly the presence of two steady Dean vortices. Therefore, results confirm that helical flow constitutes an important flow signature in vessels, and its strength as a fluid dynamic index.

Large eddy simulation and experimental study on vented gasoline-air mixture explosions in a semi-confined obstructed pipe.

PubMed

Li, Guoqing; Du, Yang; Wang, Shimao; Qi, Sheng; Zhang, Peili; Chen, Wenzhuo

2017-10-05

In this work, LES simulation coupled with a TFC sub-grid combustion model has been performed in a semi-confined pipe (L/D=10, V=10L) in the presence of four hollow-square obstacles (BR=49.8%) with circular hollow cross-section, in order to study the premixed gasoline-air mixture explosions. The comparisons between simulated results and experimental results have been conducted. It was found that the simulated results were in good agreement with experimental data in terms of flame structures, flame locations and overpressure time histories. Moreover, the interaction between flame propagation process and obstacles, overpressure dynamics were analyzed. In addition, the effects of initial gasoline vapor concentration (lean (ϕ=1.3%), stoichiometric (ϕ=1.7%) and rich (ϕ=2.1%)), and the number of obstacles (from 1 to 4) were also investigated by experiments. Some of the experimental results have been compared with the literature data. It is found that the explosion parameters of gasoline-air mixtures (e.g. the maximum overpressure peaks, average overpressure growth rates, etc.) are different from some other fuels such as hydrogen, methane and LPG, etc. Copyright © 2017. Published by Elsevier B.V.

Air flow quality analysis of modenas engine exhaust system

NASA Astrophysics Data System (ADS)

Shahriman A., B.; Mohamad Syafiq A., K.; Hashim, M. S. M.; Razlan, Zuradzman M.; Khairunizam W. A., N.; Hazry, D.; Afendi, Mohd; Daud, R.; Rahman, M. D. Tasyrif Abdul; Cheng, E. M.; Zaaba, S. K.

2017-09-01

The simulation process being conducted to determine the air flow effect between the original exhaust system and modified exhaust system. The simulations are conducted to investigate the flow distribution of exhaust gases that will affect the performance of the engine. The back flow pressure in the original exhaust system is predicted toward this simulation. The design modification to the exhaust port, exhaust pipe, and exhaust muffler has been done during this simulation to reduce the back flow effect. The new designs are introduced by enlarging the diameter of the exhaust port, enlarge the diameter of the exhaust pipe and created new design for the exhaust muffler. Based on the result obtained, there the pulsating flow form at the original exhaust port that will increase the velocity and resulting the back pressure occur. The result for new design of exhaust port, the velocity is lower at the valve guide in the exhaust port. New design muffler shows that the streamline of the exhaust flow move smoothly compare to the original muffler. It is proved by using the modification exhaust system, the back pressure are reduced and the engine performance can be improve.

Filament winding technique, experiment and simulation analysis on tubular structure

NASA Astrophysics Data System (ADS)

Quanjin, Ma; Rejab, M. R. M.; Kaige, Jiang; Idris, M. S.; Harith, M. N.

2018-04-01

Filament winding process has emerged as one of the potential composite fabrication processes with lower costs. Filament wound products involve classic axisymmetric parts (pipes, rings, driveshafts, high-pressure vessels and storage tanks), non-axisymmetric parts (prismatic nonround sections and pipe fittings). Based on the 3-axis filament winding machine has been designed with the inexpensive control system, it is completely necessary to make a relative comparison between experiment and simulation on tubular structure. In this technical paper, the aim of this paper is to perform a dry winding experiment using the 3-axis filament winding machine and simulate winding process on the tubular structure using CADWIND software with 30°, 45°, 60° winding angle. The main result indicates that the 3-axis filament winding machine can produce tubular structure with high winding pattern performance with different winding angle. This developed 3-axis winding machine still has weakness compared to CAWIND software simulation results with high axes winding machine about winding pattern, turnaround impact, process error, thickness, friction impact etc. In conclusion, the 3-axis filament winding machine improvements and recommendations come up with its comparison results, which can intuitively understand its limitations and characteristics.

ClimatePipes: User-Friendly Data Access, Manipulation, Analysis & Visualization of Community Climate Models

NASA Astrophysics Data System (ADS)

Chaudhary, A.; DeMarle, D.; Burnett, B.; Harris, C.; Silva, W.; Osmari, D.; Geveci, B.; Silva, C.; Doutriaux, C.; Williams, D. N.

2013-12-01

The impact of climate change will resonate through a broad range of fields including public health, infrastructure, water resources, and many others. Long-term coordinated planning, funding, and action are required for climate change adaptation and mitigation. Unfortunately, widespread use of climate data (simulated and observed) in non-climate science communities is impeded by factors such as large data size, lack of adequate metadata, poor documentation, and lack of sufficient computational and visualization resources. We present ClimatePipes to address many of these challenges by creating an open source platform that provides state-of-the-art, user-friendly data access, analysis, and visualization for climate and other relevant geospatial datasets, making the climate data available to non-researchers, decision-makers, and other stakeholders. The overarching goals of ClimatePipes are: - Enable users to explore real-world questions related to climate change. - Provide tools for data access, analysis, and visualization. - Facilitate collaboration by enabling users to share datasets, workflows, and visualization. ClimatePipes uses a web-based application platform for its widespread support on mainstream operating systems, ease-of-use, and inherent collaboration support. The front-end of ClimatePipes uses HTML5 (WebGL, Canvas2D, CSS3) to deliver state-of-the-art visualization and to provide a best-in-class user experience. The back-end of the ClimatePipes is built around Python using the Visualization Toolkit (VTK, http://vtk.org), Climate Data Analysis Tools (CDAT, http://uv-cdat.llnl.gov), and other climate and geospatial data processing tools such as GDAL and PROJ4. ClimatePipes web-interface to query and access data from remote sources (such as ESGF). Shown in the figure is climate data layer from ESGF on top of map data layer from OpenStreetMap. The ClimatePipes workflow editor provides flexibility and fine grained control, and uses the VisTrails (http://www.vistrails.org) workflow engine in the backend.

Measurements of Integration Gain for the Cospas-Sarsat System from Geosynchronous Satellites

NASA Technical Reports Server (NTRS)

Klein-Lebbink, Elizabeth; Christo, James; Peters, Robert; Nguyen, Xuan

2015-01-01

The GOES-R satellite is the first satellite to use a standard straight bent pipe transponder with no on-board re-modulation to support Search and Rescue (SAR) operations. Here, we report on the link measurements with a high fidelity satellite transponder simulator made up of satellite EDU (Engineering Design Units) components using an uplink from a beacon simulator and received by a GEOLUT (GEOsynchronous satellite Local User Terminal). We also report on the first ever measurements showing the performance gain obtained by the signal integration performed by the GEOLUT. In addition, a simulator made of commercially available off-the-shelf components assembled to develop the test plan was found to perform very close to the high fidelity simulator. In this paper, we describe what message integration is, how it is implemented in the particular satellite receiving station model used for this tests, and show the measured improvement in message decoding due to this integration process. These are the first tests to quantify the integration gain and are the first tests on the new SARSAT standard for the bent pipe (no onboard re-modulation) repeater used in GOES-R. An inexpensive satellite simulator to run test scripts built from off the shelf components was also found to have the same performance as a high fidelity simulator using actual satellite EDUs.

Development of a Remote External Repair Tool for Damaged or Defective Polyethylene Pipe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kenneth H. Green; Willie E. Rochefort; Nick Wannenmacher

2006-06-30

Current procedures for repairing polyethylene (PE) gas pipe require excavation, isolation, and removal of the damaged section of pipe followed by fusing a new section of pipe into place. These techniques are costly and very disruptive. An alternative repair method was developed at Timberline Tool with support from Oregon State University (OSU) and funding by the U. S. Department of Energy National Energy Technology Laboratory (DOE/NETL). This project was undertaken to design, develop and test a tool and method for repairing damaged PE pipe remotely and externally in situ without squeezing off the flow of gas, eliminating the need formore » large-scale excavations. Through an iterative design and development approach, a final engineered prototype was developed that utilizes a unique thermo-chemical and mechanical process to apply a permanent external patch to repair small nicks, gouges and punctures under line pressure. The project identified several technical challenges during the design and development process. The repair tool must be capable of being installed under live conditions and operate in an 18-inch keyhole. This would eliminate the need for extensive excavations thus reducing the cost of the repair. Initially, the tool must be able to control the leak by encapsulating the pipe and apply slight pressure at the site of damage. Finally, the repair method must be permanent at typical operating pressures. The overall results of the project have established a permanent external repair method for use on damaged PE gas pipe in a safe and cost-effective manner. The engineered prototype was subjected to comprehensive testing and evaluation to validate the performance. Using the new repair tool, samples of 4-inch PE pipe with simulated damage were successfully repaired under line pressure to the satisfaction of DOE/NETL and the following natural gas companies: Northwest Natural; Sempra Energy, Southwest Gas Corporation, Questar, and Nicor. However, initial results of accelerated age testing on repaired pipe samples showed that the high density polyethylene (HDPE) pipe patch material developed a small crack at the high stress areas surrounding the patched hole within the first 48 hours of hot water testing, indicating that the patch material has a 25-year lifespan. Based on these results, further research is continuing to develop a stronger repair patch for a satisfactory 50-year patch system. Additional tests were also conducted to evaluate whether any of the critical performance properties of the PE pipe were reduced or compromised by the repair technique. This testing validated a satisfactory 50-year patch system for the pipe.« less

Using WNTR to Model Water Distribution System Resilience ...

EPA Pesticide Factsheets

The Water Network Tool for Resilience (WNTR) is a new open source Python package developed by the U.S. Environmental Protection Agency and Sandia National Laboratories to model and evaluate resilience of water distribution systems. WNTR can be used to simulate a wide range of disruptive events, including earthquakes, contamination incidents, floods, climate change, and fires. The software includes the EPANET solver as well as a WNTR solver with the ability to model pressure-driven demand hydraulics, pipe breaks, component degradation and failure, changes to supply and demand, and cascading failure. Damage to individual components in the network (i.e. pipes, tanks) can be selected probabilistically using fragility curves. WNTR can also simulate different types of resilience-enhancing actions, including scheduled pipe repair or replacement, water conservation efforts, addition of back-up power, and use of contamination warning systems. The software can be used to estimate potential damage in a network, evaluate preparedness, prioritize repair strategies, and identify worse case scenarios. As a Python package, WNTR takes advantage of many existing python capabilities, including parallel processing of scenarios and graphics capabilities. This presentation will outline the modeling components in WNTR, demonstrate their use, give the audience information on how to get started using the code, and invite others to participate in this open source project. This pres

Investigation on the hot melting temperature field simulation of HDPE water supply pipeline in gymnasium pool

NASA Astrophysics Data System (ADS)

Cai, Zhiqiang; Dai, Hongbin; Fu, Xibin

2018-06-01

In view of the special needs of the water supply and drainage system of swimming pool in gymnasium, the correlation of high density polyethylene (HDPE) pipe and the temperature field distribution during welding was investigated. It showed that the temperature field distribution has significant influence on the quality of welding. Moreover, the mechanical properties of the welded joint were analyzed by the bending test of the weld joint, and the micro-structure of the welded joint was evaluated by scanning electron microscope (SEM). The one-dimensional unsteady heat transfer model of polyethylene pipe welding joints was established by MARC. The temperature field distribution during welding process was simulated, and the temperature field changes during welding were also detected and compared by the thermo-couple temperature automatic acquisition system. Results indicated that the temperature of the end surface of the pipe does not reach the maximum value, when it is at the end of welding heating. Instead, it reaches the maximum value at 300 sand latent heat occurs during the welding process. It concludes that the weld quality is the highest when the welding pressure is 0.2 MPa, and the heating temperature of HDPE heat fusion welding is in the range of 210 °C-230 °C.

Safe Affordable Fission Engine-(SAFE-) 100a Heat Exchanger Thermal and Structural Analysis

NASA Technical Reports Server (NTRS)

Steeve, B. E.

2005-01-01

A potential fission power system for in-space missions is a heat pipe-cooled reactor coupled to a Brayton cycle. In this system, a heat exchanger (HX) transfers the heat of the reactor core to the Brayton gas. The Safe Affordable Fission Engine- (SAFE-) 100a is a test program designed to thermally and hydraulically simulate a 95 Btu/s prototypic heat pipe-cooled reactor using electrical resistance heaters on the ground. This Technical Memorandum documents the thermal and structural assessment of the HX used in the SAFE-100a program.

Steady-state and transient operation of a heat-pipe radiator system

NASA Technical Reports Server (NTRS)

Sellers, J. P.

1974-01-01

Data obtained on a VCHP heat-pipe radiator system tested in a vacuum environment were studied. Analyses and interpretation of the steady-state results are presented along with an initial analysis of some of the transient data. Particular emphasis was placed on quantitative comparisons of the experimental data with computer model simulations. The results of the study provide a better understanding of the system but do not provide a complete explanation for the observed low VCHP performance and the relatively flat radiator panel temperature distribution. The results of the study also suggest hardware, software, and testing improvements.

Nonlinear soil parameter effects on dynamic embedment of offshore pipeline on soft clay

NASA Astrophysics Data System (ADS)

Yu, Su Young; Choi, Han Suk; Lee, Seung Keon; Park, Kyu-Sik; Kim, Do Kyun

2015-06-01

In this paper, the effects of nonlinear soft clay on dynamic embedment of offshore pipeline were investigated. Seabed embedment by pipe-soil interactions has impacts on the structural boundary conditions for various subsea structures such as pipeline, riser, pile, and many other systems. A number of studies have been performed to estimate real soil behavior, but their estimation of seabed embedment has not been fully identified and there are still many uncertainties. In this regards, comparison of embedment between field survey and existing empirical models has been performed to identify uncertainties and investigate the effect of nonlinear soil parameter on dynamic embedment. From the comparison, it is found that the dynamic embedment with installation effects based on nonlinear soil model have an influence on seabed embedment. Therefore, the pipe embedment under dynamic condition by nonlinear parameters of soil models was investigated by Dynamic Embedment Factor (DEF) concept, which is defined as the ratio of the dynamic and static embedment of pipeline, in order to overcome the gap between field embedment and currently used empirical and numerical formula. Although DEF through various researches is suggested, its range is too wide and it does not consider dynamic laying effect. It is difficult to find critical parameters that are affecting to the embedment result. Therefore, the study on dynamic embedment factor by soft clay parameters of nonlinear soil model was conducted and the sensitivity analyses about parameters of nonlinear soil model were performed as well. The tendency on dynamic embedment factor was found by conducting numerical analyses using OrcaFlex software. It is found that DEF was influenced by shear strength gradient than other factors. The obtained results will be useful to understand the pipe embedment on soft clay seabed for applying offshore pipeline designs such as on-bottom stability and free span analyses.

Role of iron and aluminum coagulant metal residuals and lead release from drinking water pipe materials.

PubMed

Knowles, Alisha D; Nguyen, Caroline K; Edwards, Marc A; Stoddart, Amina; McIlwain, Brad; Gagnon, Graham A

2015-01-01

Bench-scale experiments investigated the role of iron and aluminum residuals in lead release in a low alkalinity and high (> 0.5) chloride-to-sulfate mass ratio (CSMR) in water. Lead leaching was examined for two lead-bearing plumbing materials, including harvested lead pipe and new lead: tin solder, after exposure to water with simulated aluminum sulfate, polyaluminum chloride and ferric sulfate coagulation treatments with 1-25-μM levels of iron or aluminum residuals in the water. The release of lead from systems with harvested lead pipe was highly correlated with levels of residual aluminum or iron present in samples (R(2) = 0.66-0.88), consistent with sorption of lead onto the aluminum and iron hydroxides during stagnation. The results indicate that aluminum and iron coagulant residuals, at levels complying with recommended guidelines, can sometimes play a significant role in lead mobilization from premise plumbing.

Reactive Transport in a Pipe in Soluble Rock: a Theoretical and Experimental Study

NASA Astrophysics Data System (ADS)

Li, W.; Opolot, M.; Sousa, R.; Einstein, H. H.

2015-12-01

Reactive transport processes within the dominant underground flow pathways such as fractures can lead to the widening or narrowing of rock fractures, potentially altering the flow and transport processes in the fractures. A flow-through experiment was designed to study the reactive transport process in a pipe in soluble rock to serve as a simplified representation of a fracture in soluble rock. Assumptions were made to formulate the problem as three coupled, one-dimensional partial differential equations: one for the flow, one for the transport and one for the radius change due to dissolution. Analytical and numerical solutions were developed to predict the effluent concentration and the change in pipe radius. The positive feedback of the radius increase is captured by the experiment and the numerical model. A comparison between the experiment and the simulation results demonstrates the validity of the analytical and numerical models.

Direct numerical simulation of turbulent flow with an impedance condition

NASA Astrophysics Data System (ADS)

Olivetti, Simone; Sandberg, Richard D.; Tester, Brian J.

2015-05-01

DNS solutions for a pipe/jet configuration are re-computed with the pipe alone to investigate suppression of previously identified internal noise source(s) with an acoustic liner, using a time domain acoustic liner model developed by Tam and Auriault (AIAA Journal, 34 (1996) 913-917). Liner design parameters are chosen to achieve up to 30 dB attenuation of the broadband pressure field over the pipe length without affecting the velocity field statistics. To understand the effect of the liner on the acoustic and turbulent components of the unsteady wall pressure, an azimuthal/axial Fourier transform is applied and the acoustic and turbulent wavenumber regimes clearly identified. It is found that the spectral component occupying the turbulent wavenumber range is unaffected by the liner whereas the acoustic wavenumber components are strongly attenuated, with individual radial modes being evident as each cuts on with increasing Strouhal number.

Micro-light-pipe array with an excitation attenuation filter for lensless digital enzyme-linked immunosorbent assay

NASA Astrophysics Data System (ADS)

Takehara, Hironari; Nagasaki, Mizuki; Sasagawa, Kiyotaka; Takehara, Hiroaki; Noda, Toshihiko; Tokuda, Takashi; Ohta, Jun

2016-03-01

Digital enzyme-linked immunosorbent assay (ELISA) is used for detecting various biomarkers with hypersensitivity. We have been developing compact systems by replacing the fluorescence microscope with a CMOS image sensor. Here, we propose a micro-light-pipe array structure made of metal filled with dye-doped resin, which can be used as a fabrication substrate of the micro-reaction-chamber array of digital ELISA. The possibility that this structure enhances the coupling efficiency for fluorescence was simulated using a simple model. To realize the structure, we fabricated a 30-µm-thick micropipe array by copper electroplating around a thick photoresist pattern. The typical diameter of each fabricated micropipe was 10 µm. The pipes were filled with yellow-dye-doped epoxy resin. The transmittance ratio of fluorescence and excitation light could be controlled by adjusting the doping concentration. We confirmed that an angled excitation light incidence suppressed the leakage of excitation light.

Investigation of the effects of inlet shapes on fan noise radiation

NASA Technical Reports Server (NTRS)

Clark, T. L.; Slotboom, D. R.; Vaidya, P. G.

1981-01-01

The effect of inlet shape on forward radiated fan tone noise directivities was investigated under experimentally simplified zero flow conditions. Simulated fan tone noise was radiated to the far field through various shaped zero flow inlets. Baseline data were collected for the simplest baffled and unbaffled straight pipe inlets. These data compared well with prediction. The more general inlet shapes tested were the conical, circular, and exponential surfaces of revolution and an asymmetric inlet achieved by cutting a straight pipe inlet at an acute angle. Approximate theories were developed for these general shapes and some comparisons with data are presented. The conical and exponential shapes produced directivities that differed considerably from the baseline data while the circular shape produced directivities similar to the baseline data. The asymmetric inlet produced asymmetric directivities with significant reductions over the straight pipe data for some angles.

Demographics and movements of least terns and piping plovers in the Central Platte River Valley, Nebraska

USGS Publications Warehouse

Roche, Erin A.; Sherfy, Mark H.; Ring, Megan M.; Shaffer, Terry L.; Anteau, Michael J.; Stucker, Jennifer H.

2016-08-09

The Central Platte River Valley provides breeding habitat for a variety of migratory birds, including federally endangered interior least terns (Sternula antillarum; least tern) and threatened piping plovers (Charadrius melodus). Since 2009, researchers have collected demographic data on both species that span their lifecycle (that is, from egg laying through survival of adults). Demographic data were used to estimate vital rates (for example, nest survival, chick survival, and so on) for both species and assess how these vital rates were related to type and age of nesting habitat. Nest survival of both species was unrelated to the age of the site a nest was initiated on. Piping plover chick survival to fledging age was not related to the age of the site it was hatched at, however, the probability of a least tern chick surviving to fledging was higher at older sites. In general there were fewer piping plover nests than least tern nests found at sites created through either the physical construction of a new site or new vegetation management regimes, during 2009–14.Mean daily least tern nest survival was 0.9742 (95-percent confidence interval [CI]: 0.9692–0.9783) and cumulative nest survival was 0.59 (95-percent CI: 0.53–0.65). Mean daily least tern chick survival was 0.9602 (95-percent CI: 0.9515–0.9673) and cumulative survival to fledging was 0.54 (95-percent CI = 0.48–0.61). Annual apparent survival rates were estimated at 0.42 (95-percent CI = 0.22–0.64) for adult least terns nesting in the Central Platte River Valley and an apparent survival rate of 0.14 (95-pecent CI = 0.04–0.41) for juvenile least terns. The number of least tern nests present at sites created during 2009–14 was associated with the age of the site; more least tern nests were associated with older sites. During 2009–14, there were four (less than 1 percent of all chicks marked) least tern chicks hatched from the Central Platte River Valley that were subsequently captured on nests as adults. Two of these least terns returned to nest at the same site they had hatched from. Ten instances were documented in which an adult least tern could either switch to nest at a new location or remain at the previous location with the onset of a new year. In five (50 percent) of these instances, least terns returned to nest on the site where they had nested in a previous year.For piping plovers, mean daily apparent nest survival was 0.9880 (95-pecent CI: 0.9836–0.9912) and cumulative nest survival was 0.66 (95-pecent CI: 0.57–0.74). Mean daily piping plover chick survival was 0.9621 (95-pecent CI: 0.9514–0.9706) and cumulative survival to fledging was 0.46 (95-pecent CI = 0.37– 0.56). The annual apparent survival estimate for adult piping plovers nesting in the Central Platte River Valley was 0.76 (95-pecent CI = 0.65–0.85) and was 0.20 (95-pecent CI = 0.14–0.29) for juvenile piping plovers. The number of piping plover nests present at sites created through either the physical construction of a new site or new vegetation management regimes was also associated with site age, with more piping plover nests associated with older sites; however, in general there were fewer piping plover nests found at created sites than least tern nests. Only first-year adult piping plovers were observed on sites in the first year of availability, whereas older sites had a higher proportion of after-first-year adult piping plovers than first-year adult piping plovers. Twelve piping plover chicks (approximately 3 percent of all chicks marked) hatched from the Central Platte River Valley and were subsequently documented on nests as adults. All piping plovers returned to nest on different sites from the one on which they hatched. A total of 45 instances were documented in which an adult plover could either switch to nest at a new location or remain at the previous location with the onset of a new year. In 39 instances (87 percent), the adult nested on the same site as its prior documented nesting attempt and in 6 of these instances the adult switched to a new nesting location between years. There were 13 of 75 uniquely identifiable piping plovers observed to renest (that is, initiate more than one nest in a season) during 2009–14; no renests were observed among uniquely identifiable least terns. In all but one case, piping plover renests were found at the same site as the first nest initiated that season. For birds that renested, the mean initiation date of the first nest was May 6 and the mean initiation date of the second nest was June 8. On average, renests were initiated 7.5 days plus or minus 7.3 (SD [standard deviation]) following the date the initial nesting attempt was ‘fated’ (considered either failed or hatched).

Dam break analysis and flood inundation map of Krisak dam for emergency action plan

NASA Astrophysics Data System (ADS)

Juliastuti, Setyandito, Oki

2017-11-01

The Indonesian Regulation which refers to the ICOLD Regulation (International Committee on Large Dam required have the Emergency Action Plan (EAP) guidelines because of the dams have potential failure. In EAP guidelines there is a management of evacuation where the determination of the inundation map based on flood modeling. The purpose of the EAP is to minimize the risk of loss of life and property in downstream which caused by dam failure. This paper will describe about develop flood modeling and inundation map in Krisak dam using numerical methods through dam break analysis (DBA) using hydraulic model Zhong Xing HY-21. The approaches of dam failure simulation are overtopping and piping. Overtopping simulation based on quadrangular, triangular and trapezium fracture. Piping simulation based on cracks of orifice. Using results of DBA, hazard classification of Krisak dam is very high. The nearest village affected dam failure is Singodutan village (distance is 1.45 kilometer from dam) with inundation depth is 1.85 meter. This result can be used by stakeholders such as emergency responders and the community at risk in formulating evacuation procedure.

Flow topology of rare back flow events and critical points in turbulent channels and toroidal pipes

NASA Astrophysics Data System (ADS)

Chin, C.; Vinuesa, R.; Örlü, R.; Cardesa, J. I.; Noorani, A.; Schlatter, P.; Chong, M. S.

2018-04-01

A study of the back flow events and critical points in the flow through a toroidal pipe at friction Reynolds number Re τ ≈ 650 is performed and compared with the results in a turbulent channel flow at Re τ ≈ 934. The statistics and topological properties of the back flow events are analysed and discussed. Conditionally-averaged flow fields in the vicinity of the back flow event are obtained, and the results for the torus show a similar streamwise wall-shear stress topology which varies considerably for the spanwise wall-shear stress when compared to the channel flow. The comparison between the toroidal pipe and channel flows also shows fewer back flow events and critical points in the torus. This cannot be solely attributed to differences in Reynolds number, but is a clear effect of the secondary flow present in the toroidal pipe. A possible mechanism is the effect of the secondary flow present in the torus, which convects momentum from the inner to the outer bend through the core of the pipe, and back from the outer to the inner bend through the pipe walls. In the region around the critical points, the skin-friction streamlines and vorticity lines exhibit similar flow characteristics with a node and saddle pair for both flows. These results indicate that back flow events and critical points are genuine features of wall-bounded turbulence, and are not artifacts of specific boundary or inflow conditions in simulations and/or measurement uncertainties in experiments.

The energy transfer mechanism of a perturbed solid-body rotation flow in a rotating pipe

NASA Astrophysics Data System (ADS)

Feng, Chunjuan; Liu, Feng; Rusak, Zvi; Wang, Shixiao

2017-04-01

Three-dimensional direct numerical simulations of a solid-body rotation superposed on a uniform axial flow entering a rotating constant-area pipe of finite length are presented. Steady in time profiles of the radial, axial, and circumferential velocities are imposed at the pipe inlet. Convective boundary conditions are imposed at the pipe outlet. The Wang and Rusak (Phys. Fluids 8:1007-1016, 1996. doi: 10.1063/1.86882) axisymmetric instability mechanism is retrieved at certain operational conditions in terms of incoming flow swirl levels and the Reynolds number. However, at other operational conditions there exists a dominant, three-dimensional spiral type of instability mode that is consistent with the linear stability theory of Wang et al. (J. Fluid Mech. 797: 284-321, 2016). The growth of this mode leads to a spiral type of flow roll-up that subsequently nonlinearly saturates on a large amplitude rotating spiral wave. The energy transfer mechanism between the bulk of the flow and the perturbations is studied by the Reynolds-Orr equation. The production or loss of the perturbation kinetic energy is combined of three components: the viscous loss, the convective loss at the pipe outlet, and the gain of energy at the outlet through the work done by the pressure perturbation. The energy transfer in the nonlinear stage is shown to be a natural extension of the linear stage with a nonlinear saturated process.

Development of a Flexible Broadband Rayleigh Waves Comb Transducer with Nonequidistant Comb Interval for Defect Detection of Thick-Walled Pipelines

PubMed Central

He, Cunfu; Yan, Lyu; Zhang, Haijun

2018-01-01

It is necessary to develop a transducer that can quickly detect the inner and outer wall defects of thick-walled pipes, in order to ensure the safety of such pipes. In this paper, a flexible broadband Rayleigh-waves comb transducer based on PZT (lead zirconate titanate) for defect detection of thick-walled pipes is studied. The multiple resonant coupling theory is used to expand the transducer broadband and the FEA (Finite Element Analysis) method is used to optimize transducer array element parameters. Optimization results show that the best array element parameters of the transducer are when the transducer array element length is 30 mm, the thickness is 1.2 mm, the width of one end of is 1.5 mm, and the other end is 3 mm. Based on the optimization results, such a transducer was fabricated and its performance was tested. The test results were consistent with the finite-element simulation results, and the −3 dB bandwidth of the transducer reached 417 kHz. Transducer directivity test results show that the Θ−3dB beam width was equal to 10 °, to meet the defect detection requirements. Finally, defects of thick-walled pipes were detected using the transducer. The results showed that the transducer could detect the inner and outer wall defects of thick-walled pipes within the bandwidth. PMID:29498636

Development of a Flexible Broadband Rayleigh Waves Comb Transducer with Nonequidistant Comb Interval for Defect Detection of Thick-Walled Pipelines.

PubMed

Zhao, Huamin; He, Cunfu; Yan, Lyu; Zhang, Haijun

2018-03-02

It is necessary to develop a transducer that can quickly detect the inner and outer wall defects of thick-walled pipes, in order to ensure the safety of such pipes. In this paper, a flexible broadband Rayleigh-waves comb transducer based on PZT (lead zirconate titanate) for defect detection of thick-walled pipes is studied. The multiple resonant coupling theory is used to expand the transducer broadband and the FEA (Finite Element Analysis) method is used to optimize transducer array element parameters. Optimization results show that the best array element parameters of the transducer are when the transducer array element length is 30 mm, the thickness is 1.2 mm, the width of one end of is 1.5 mm, and the other end is 3 mm. Based on the optimization results, such a transducer was fabricated and its performance was tested. The test results were consistent with the finite-element simulation results, and the -3 dB bandwidth of the transducer reached 417 kHz. Transducer directivity test results show that the Θ -3dB beam width was equal to 10 °, to meet the defect detection requirements. Finally, defects of thick-walled pipes were detected using the transducer. The results showed that the transducer could detect the inner and outer wall defects of thick-walled pipes within the bandwidth.

Structural Integrity of Water Reactor Pressure Boundary Components.

DTIC Science & Technology

1981-02-20

environment, and load waveform parameters . A theory of the influence of dissolved oxygen content on the fatigue crack growth results in simulated PWR ...simulated PWR coolant is - (Continues ) DD IJN7 1473 EDITION OF I NOV S ..OSL- -C 2 S/ 0102-LF-014-6601 S1ECURITY CLASSI1FICATION OF THIS PAGE (When...not seem to influence the data, which was produced for a load ratio of 0.2 and a simulated PWR coolant environment. Test results for A106 Grade C piping

Corrosion impact of reductant on DWPF and downstream facilities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mickalonis, J. I.; Imrich, K. J.; Jantzen, C. M.

2014-12-01

Glycolic acid is being evaluated as an alternate reductant in the preparation of high level waste for the Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS). During processing, the glycolic acid is not completely consumed and small quantities of the glycolate anion are carried forward to other high level waste (HLW) facilities. The impact of the glycolate anion on the corrosion of the materials of construction throughout the waste processing system has not been previously evaluated. A literature review had revealed that corrosion data in glycolate-bearing solution applicable to SRS systems were not available. Therefore, testing wasmore » recommended to evaluate the materials of construction of vessels, piping and components within DWPF and downstream facilities. The testing, conducted in non-radioactive simulants, consisted of both accelerated tests (electrochemical and hot-wall) with coupons in laboratory vessels and prototypical tests with coupons immersed in scale-up and mock-up test systems. Eight waste or process streams were identified in which the glycolate anion might impact the performance of the materials of construction. These streams were 70% glycolic acid (DWPF feed vessels and piping), SRAT/SME supernate (Chemical Processing Cell (CPC) vessels and piping), DWPF acidic recycle (DWPF condenser and recycle tanks and piping), basic concentrated recycle (HLW tanks, evaporators, and transfer lines), salt processing (ARP, MCU, and Saltstone tanks and piping), boric acid (MCU separators), and dilute waste (HLW evaporator condensate tanks and transfer line and ETF components). For each stream, high temperature limits and worst-case glycolate concentrations were identified for performing the recommended tests. Test solution chemistries were generally based on analytical results of actual waste samples taken from the various process facilities or of prototypical simulants produced in the laboratory. The materials of construction for most vessels, components and piping were not impacted with the presence of glycolic acid or the impact is not expected to affect the service life. However, the presence of the glycolate anion was found to affect corrosion susceptibility of some materials of construction in the DWPF and downstream facilities, especially at elevated temperatures. The following table summarizes the results of the electrochemical and hot wall testing and indicates expected performance in service with the glycolate anion present.« less

Noise Radiation Of A Strongly Pulsating Tailpipe Exhaust

NASA Astrophysics Data System (ADS)

Peizi, Li; Genhua, Dai; Zhichi, Zhu

1993-11-01

The method of characteristics is used to solve the problem of the propagation of a strongly pulsating flow in an exhaust system tailpipe. For a strongly pulsating exhaust, the flow may shock at the pipe's open end at some point in a pulsating where the flow pressure exceeds its critical value. The method fails if one insists on setting the flow pressure equal to the atmospheric pressure as the pipe end boundary condition. To solve the problem, we set the Mach number equal to 1 as the boundary condition when the flow pressure exceeds its critical value. For a strongly pulsating flow, the fluctuations of flow variables may be much higher than their respective time averages. Therefore, the acoustic radiation method would fail in the computation of the noise radiation from the pipe's open end. We simulate the exhaust flow out of the open end as a simple sound source to compute the noise radiation, which has been successfully applied in reference [1]. The simple sound source strength is proportional to the volume acceleration of exhaust gas. Also computed is the noise radiation from the turbulence of the exhaust flow, as was done in reference [1]. Noise from a reciprocating valve simulator has been treated in detail. The radiation efficiency is very low for the pressure range considered and is about 10 -5. The radiation efficiency coefficient increases with the square of the frequency. Computation of the pipe length dependence of the noise radiation and mass flux allows us to design a suitable length for an aerodynamic noise generator or a reciprocating internal combustion engine. For the former, powerful noise radiation is preferable. For the latter, maximum mass flux is desired because a freer exhaust is preferable.

References and benchmarks for pore-scale flow simulated using micro-CT images of porous media and digital rocks

NASA Astrophysics Data System (ADS)

Saxena, Nishank; Hofmann, Ronny; Alpak, Faruk O.; Berg, Steffen; Dietderich, Jesse; Agarwal, Umang; Tandon, Kunj; Hunter, Sander; Freeman, Justin; Wilson, Ove Bjorn

2017-11-01

We generate a novel reference dataset to quantify the impact of numerical solvers, boundary conditions, and simulation platforms. We consider a variety of microstructures ranging from idealized pipes to digital rocks. Pore throats of the digital rocks considered are large enough to be well resolved with state-of-the-art micro-computerized tomography technology. Permeability is computed using multiple numerical engines, 12 in total, including, Lattice-Boltzmann, computational fluid dynamics, voxel based, fast semi-analytical, and known empirical models. Thus, we provide a measure of uncertainty associated with flow computations of digital media. Moreover, the reference and standards dataset generated is the first of its kind and can be used to test and improve new fluid flow algorithms. We find that there is an overall good agreement between solvers for idealized cross-section shape pipes. As expected, the disagreement increases with increase in complexity of the pore space. Numerical solutions for pipes with sinusoidal variation of cross section show larger variability compared to pipes of constant cross-section shapes. We notice relatively larger variability in computed permeability of digital rocks with coefficient of variation (of up to 25%) in computed values between various solvers. Still, these differences are small given other subsurface uncertainties. The observed differences between solvers can be attributed to several causes including, differences in boundary conditions, numerical convergence criteria, and parameterization of fundamental physics equations. Solvers that perform additional meshing of irregular pore shapes require an additional step in practical workflows which involves skill and can introduce further uncertainty. Computation times for digital rocks vary from minutes to several days depending on the algorithm and available computational resources. We find that more stringent convergence criteria can improve solver accuracy but at the expense of longer computation time.

Turbulent spots and scalar flashes in pipe transition

NASA Astrophysics Data System (ADS)

Adrian, Ronald; Wu, Xiaohua; Moin, Parviz

2017-11-01

Recent study (Wu et al., PNAS, 1509451112, 2015) demonstrated the feasibility and accuracy of direct computation of the Osborne Reynolds' pipe transition experiment without the unphysical axially periodic boundary condition. Here we use this approach to address three questions: (1) What are the dynamics of turbulent spot generation in pipe transition? (2) How is the succession of scalar flashes, as observed and sketched by Osborne Reynolds, created? (3) What happens to the succession of flashes further downstream? In this study, the inlet disturbance is of radial-mode type imposed through a narrow, three-degree numerical wedge; and the simulation Reynolds number is 6500. Numerical dye is introduced at the inlet plane locally very close to the pipe axis, similar to the needle injection by O. Reynolds. Inception of infant turbulent spots occurs when normal, forward inclined hairpin packets form near the walls from the debris of the inlet perturbations. However, the young and mature turbulent spots consist almost exclusively of reverse, backward leaning hairpin vortices. Scalar flashes appear successively downstream and persist well into the fully-developed turbulent region. Their creation mechanism is addressed. RJA gratefully acknowledges support of the National Science Foundation with NSF Award CBET-0933848.

Role of drinking water biofilms on residual chlorine decay and trihalomethane formation: An experimental and modeling study.

PubMed

Xu, Jianeng; Huang, Conghui; Shi, Xiaoyang; Dong, Shengkun; Yuan, Baoling; Nguyen, Thanh H

2018-06-13

PVC pipe loops were constructed to simulate household premise plumbing. These pipe loops were exposed to water treated by physical processes at three water treatment plants in Xiamen, China from August 2016 to June 2017. After the biofilms were allowed to develop inside the pipes, these pipes were deconstructed and exposed to organic-free chlorine solution buffered at pH 6.8 ± 0.2 for 48 h. The decay of chlorine by these biofilms was higher than by the effluent waters that were used to grow the biofilms. A chlorine consumption mass balance model elucidated the role of both the diffusion of chlorine into the biofilm and the reaction of chlorine with the biofilm matrix. Comparable concentrations of trihalomethanes were quantified from the reaction between chlorine and source water organic matters, and chlorine and the biofilm, further emphasizing the role of biofilms in the safety of disinfected drinking water. These findings imply that when chlorine is used in the drinking water distribution system, the ubiquitous presence of biofilms may cause the depletion of chlorine and the formation of non-negligible levels of toxic disinfection byproducts. Copyright © 2018 Elsevier B.V. All rights reserved.

Preliminary research on flow rate and free surface of the accelerator driven subcritical system gravity-driven dense granular-flow target

PubMed Central

Li, Xiaodong; Wan, Jiangfeng; Zhang, Sheng; Lin, Ping; Zhang, Yanshi; Yang, Guanghui; Wang, Mengke; Duan, Wenshan; Sun, Jian’an

2017-01-01

A spallation target is one of the three core parts of the accelerator driven subcritical system (ADS), which has already been investigated for decades. Recently, a gravity-driven Dense Granular-flow Target (DGT) is proposed, which consists of a cylindrical hopper and an internal coaxial cylindrical beam pipe. The research on the flow rate and free surface are important for the design of the target whether in Heavy Liquid Metal (HLM) targets or the DGT. In this paper, the relations of flow rate and the geometry of the DGT are investigated. Simulations based on the discrete element method (DEM) implementing on Graphics Processing Units (GPUs) and experiments are both performed. It is found that the existence of an internal pipe doesn’t influence the flow rate when the distance from the bottom of the pipe to orifice is large enough even in a larger system. Meanwhile, snapshots of the free surface formed just below the beam pipe are given. It is observed that the free surface is stable over time. The entire research is meaningful for the design of DGT. PMID:29095910

Preliminary research on flow rate and free surface of the accelerator driven subcritical system gravity-driven dense granular-flow target.

PubMed

Li, Xiaodong; Wan, Jiangfeng; Zhang, Sheng; Lin, Ping; Zhang, Yanshi; Yang, Guanghui; Wang, Mengke; Duan, Wenshan; Sun, Jian'an; Yang, Lei

2017-01-01

A spallation target is one of the three core parts of the accelerator driven subcritical system (ADS), which has already been investigated for decades. Recently, a gravity-driven Dense Granular-flow Target (DGT) is proposed, which consists of a cylindrical hopper and an internal coaxial cylindrical beam pipe. The research on the flow rate and free surface are important for the design of the target whether in Heavy Liquid Metal (HLM) targets or the DGT. In this paper, the relations of flow rate and the geometry of the DGT are investigated. Simulations based on the discrete element method (DEM) implementing on Graphics Processing Units (GPUs) and experiments are both performed. It is found that the existence of an internal pipe doesn't influence the flow rate when the distance from the bottom of the pipe to orifice is large enough even in a larger system. Meanwhile, snapshots of the free surface formed just below the beam pipe are given. It is observed that the free surface is stable over time. The entire research is meaningful for the design of DGT.

Integrated corridor management analysis, modeling, and simulation experimental plan for the test corridor.

DOT National Transportation Integrated Search

2008-03-01

This document, the AMS Experimental Plan, lays out the scope of analysis that will be conducted through the application of the AMS methodology to the Test Corridor. The specific objectives of the Experimental Plan are: create an AMS framework that id...

Evaluating methodological assumptions of a catch-curve survival estimation of unmarked precocial shorebird chickes

USGS Publications Warehouse

McGowan, Conor P.; Gardner, Beth

2013-01-01

Estimating productivity for precocial species can be difficult because young birds leave their nest within hours or days of hatching and detectability thereafter can be very low. Recently, a method for using a modified catch-curve to estimate precocial chick daily survival for age based count data was presented using Piping Plover (Charadrius melodus) data from the Missouri River. However, many of the assumptions of the catch-curve approach were not fully evaluated for precocial chicks. We developed a simulation model to mimic Piping Plovers, a fairly representative shorebird, and age-based count-data collection. Using the simulated data, we calculated daily survival estimates and compared them with the known daily survival rates from the simulation model. We conducted these comparisons under different sampling scenarios where the ecological and statistical assumptions had been violated. Overall, the daily survival estimates calculated from the simulated data corresponded well with true survival rates of the simulation. Violating the accurate aging and the independence assumptions did not result in biased daily survival estimates, whereas unequal detection for younger or older birds and violating the birth death equilibrium did result in estimator bias. Assuring that all ages are equally detectable and timing data collection to approximately meet the birth death equilibrium are key to the successful use of this method for precocial shorebirds.

CFD Application to Flow-Accelerated Corrosion in Feeder Bends

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pietralik, John M.; Smith, Bruce A.W.

2006-07-01

Feeder piping in CANDU{sup R} plants experiences a thinning degradation mechanism called Flow-Accelerated Corrosion (FAC). The piping is made of carbon steel and has high water flow speeds. Although the water chemistry is highly alkaline with room-temperature pH in a range of 10.0-10.5, the piping has FAC rates exceeding 0.1 mm/year in some locations, e.g., in bends. One of the most important parameters affecting the FAC rate is the mass transfer coefficient for convective mass transport of ferrous ions. The ions are created at the pipe wall as a result of corrosion, diffuse through the oxide layer, and are transportedmore » from the oxide-layer/water interface to the bulk water by mass transport. Consequently, the local flow characteristics contribute to the highly turbulent convective mass transfer. Plant data and laboratory experiments indicate that the mass transfer step dominates FAC under feeder conditions. In this study, the flow and mass transfer in a feeder bend under operating conditions were simulated using the Fluent{sup TM} computer code. Because the flow speed is very high, with the Reynolds numbers in a range of several millions, and because the geometry is complex, experiments in a 1:1 scale were conducted with the main objective to validate flow simulations. The experiments measured pressure at several key locations and visualized the flow. The flow and mass transfer models were validated using available friction-factor and mass transfer correlations and literature experiments on mass transfer in a bend. The validation showed that the turbulence model that best predicts the experiments is the realizable k-{epsilon} model. Other two-equation turbulence models, as well as one-equation models and Reynolds stress models were tried. The near-wall treatment used the non-equilibrium wall functions. The wall functions were modified for surface roughness when necessary. A comparison of the local mass transfer coefficient with measured FAC rate in plant specimens shows very good agreement. Visualization experiments indicate secondary flows in the bends. No boundary layer separation was observed in experiments or in simulations. (authors)« less

Prediction of contaminant fate and transport in potable water systems using H2OFate

NASA Astrophysics Data System (ADS)

Devarakonda, Venkat; Manickavasagam, Sivakumar; VanBlaricum, Vicki; Ginsberg, Mark

2009-05-01

BlazeTech has recently developed a software called H2OFate to predict the fate and transport of chemical and biological contaminants in water distribution systems. This software includes models for the reactions of these contaminants with residual disinfectant in bulk water and at the pipe wall, and their adhesion/reactions with the pipe walls. This software can be interfaced with sensors through SCADA systems to monitor water distribution networks for contamination events and activate countermeasures, as needed. This paper presents results from parametric calculations carried out using H2OFate for a simulated contaminant release into a sample water distribution network.

Numerical simulation of heat transfer to separation tio2/water nanofluids flow in an asymmetric abrupt expansion

NASA Astrophysics Data System (ADS)

Oon, Cheen Sean; Nee Yew, Sin; Chew, Bee Teng; Salim Newaz, Kazi Md; Al-Shamma'a, Ahmed; Shaw, Andy; Amiri, Ahmad

2015-05-01

Flow separation and reattachment of 0.2% TiO2 nanofluid in an asymmetric abrupt expansion is studied in this paper. Such flows occur in various engineering and heat transfer applications. Computational fluid dynamics package (FLUENT) is used to investigate turbulent nanofluid flow in the horizontal double-tube heat exchanger. The meshing of this model consists of 43383 nodes and 74891 elements. Only a quarter of the annular pipe is developed and simulated as it has symmetrical geometry. Standard k-epsilon second order implicit, pressure based-solver equation is applied. Reynolds numbers between 17050 and 44545, step height ratio of 1 and 1.82 and constant heat flux of 49050 W/m2 was utilized in the simulation. Water was used as a working fluid to benchmark the study of the heat transfer enhancement in this case. Numerical simulation results show that the increase in the Reynolds number increases the heat transfer coefficient and Nusselt number of the flowing fluid. Moreover, the surface temperature will drop to its lowest value after the expansion and then gradually increase along the pipe. Finally, the chaotic movement and higher thermal conductivity of the TiO2 nanoparticles have contributed to the overall heat transfer enhancement of the nanofluid compare to the water.

Evaluation of Environmentally Assisted Cracking of Armour Wires in Flexible Pipes, Power Cables and Umbilicals

NASA Astrophysics Data System (ADS)

Zhang, Zhiying

Environmentally assisted cracking (EAC) of armour wires in flexible pipes, power cables and umbilicals is a major concern with the development of oil and gas fields and wind farms in harsh environments. Hydrogen induced cracking (HIC) or hydrogen embrittlement (HE) of steel armour wires used in deep-water and ultra-deep-water has been evaluated. Simulated tests have been carried out in simulated sea water, under conditions where the susceptibility is the highest, i.e. at room temperature, at the maximum negative cathodic potential and at the maximum stress level expected in service for 150 hours. Examinations of the tested specimens have not revealed cracking or blistering, and measurement of hydrogen content has confirmed hydrogen charging. In addition, sulphide stress cracking (SSC) and chloride stress cracking (CSC) of nickel-based alloy armour wires used in harsh down-hole environments has been evaluated. Simulated tests have been carried out in simulated solution containing high concentration of chloride, with high hydrogen sulphide partial pressure, at high stress level and at 120 °C for 720 hours. Examinations of the tested specimens have not revealed cracking or blistering. Subsequent tensile tests of the tested specimens at ambient pressure and temperature have revealed properties similar to the as-received specimens.

Development of a Gas Dynamic and Thermodynamic Simulation Model of the Lontra Blade Compressor™

NASA Astrophysics Data System (ADS)

Karlovsky, Jerome

2015-08-01

The Lontra Blade Compressor™ is a patented double acting, internally compressing, positive displacement rotary compressor of innovative design. The Blade Compressor is in production for waste-water treatment, and will soon be launched for a range of applications at higher pressure ratios. In order to aid the design and development process, a thermodynamic and gas dynamic simulation program has been written in house. The software has been successfully used to optimise geometries and running conditions of current designs, and is also being used to evaluate future designs for different applications and markets. The simulation code has three main elements. A positive displacement chamber model, a leakage model and a gas dynamic model to simulate gas flow through ports and to track pressure waves in the inlet and outlet pipes. All three of these models are interlinked in order to track mass and energy flows within the system. A correlation study has been carried out to verify the software. The main correlation markers used were mass flow, chamber pressure, pressure wave tracking in the outlet pipe, and volumetric efficiency. It will be shown that excellent correlation has been achieved between measured and simulated data. Mass flow predictions were to within 2% of measured data, and the timings and magnitudes of all major gas dynamic effects were well replicated. The simulation will be further developed in the near future to help with the optimisation of exhaust and inlet silencers.

High spatial-temporal resolution and integrated surface and subsurface precipitation-runoff modelling for a small stormwater catchment

NASA Astrophysics Data System (ADS)

Hailegeorgis, Teklu T.; Alfredsen, Knut

2018-02-01

Reliable runoff estimation is important for design of water infrastructure and flood risk management in urban catchments. We developed a spatially distributed Precipitation-Runoff (P-R) model that explicitly represents the land cover information, performs integrated modelling of surface and subsurface components of the urban precipitation water cycle and flow routing. We conducted parameter calibration and validation for a small (21.255 ha) stormwater catchment in Trondheim City during Summer-Autumn events and season, and snow-influenced Winter-Spring seasons at high spatial and temporal resolutions of respectively 5 m × 5 m grid size and 2 min. The calibration resulted in good performance measures (Nash-Sutcliffe efficiency, NSE = 0.65-0.94) and acceptable validation NSE for the seasonal and snow-influenced periods. The infiltration excess surface runoff dominates the peak flows while the contribution of subsurface flow to the sewer pipes also augments the peak flows. Based on the total volumes of simulated flow in sewer pipes (Qsim) and precipitation (P) during the calibration periods, the Qsim/P ranges from 21.44% for an event to 56.50% for the Winter-Spring season, which are in close agreement with the observed volumes (Qobs/P). The lowest percentage of precipitation volume that is transformed to the total simulated runoff in the catchment (QT) is 79.77%. Computation of evapotranspiration (ET) indicated that the ET/P is less than 3% for the events and snow-influenced seasons while it is about 18% for the Summer-Autumn season. The subsurface flow contribution to the sewer pipes are markedly higher than the total surface runoff volume for some events and the Summer-Autumn season. The peakiest flow rates correspond to the Winter-Spring season. Therefore, urban runoff simulation for design and management purposes should include two-way interactions between the subsurface runoff and flow in sewer pipes, and snow-influenced seasons. The developed urban P-R model is useful for better computation of runoff generated from different land cover, for assessments of stormwater management techniques (e.g. the Low Impact Development or LID) and the impacts of land cover and climate change. There are some simplifications or limitations such as the runoff routing does not involve detailed sewer hydraulics, effects of leakages from water supply systems and faulty/illegal connections from sanitary sewer are not considered, the model cannot identify actual locations of the interactions between the subsurface runoff and sewer pipes and lacks parsimony.

Predicting Honeybee Colony Failure: Using the BEEHAVE Model to Simulate Colony Responses to Pesticides

PubMed Central

2015-01-01

To simulate effects of pesticides on different honeybee (Apis mellifera L.) life stages, we used the BEEHAVE model to explore how increased mortalities of larvae, in-hive workers, and foragers, as well as reduced egg-laying rate, could impact colony dynamics over multiple years. Stresses were applied for 30 days, both as multiples of the modeled control mortality and as set percentage daily mortalities to assess the sensitivity of the modeled colony both to small fluctuations in mortality and periods of low to very high daily mortality. These stresses simulate stylized exposure of the different life stages to nectar and pollen contaminated with pesticide for 30 days. Increasing adult bee mortality had a much greater impact on colony survival than mortality of bee larvae or reduction in egg laying rate. Importantly, the seasonal timing of the imposed mortality affected the magnitude of the impact at colony level. In line with the LD50, we propose a new index of “lethal imposed stress”: the LIS50 which indicates the level of stress on individuals that results in 50% colony mortality. This (or any LISx) is a comparative index for exploring the effects of different stressors at colony level in model simulations. While colony failure is not an acceptable protection goal, this index could be used to inform the setting of future regulatory protection goals. PMID:26444386

1D-3D coupling for hydraulic system transient simulations

NASA Astrophysics Data System (ADS)

Wang, Chao; Nilsson, Håkan; Yang, Jiandong; Petit, Olivier

2017-01-01

This work describes a coupling between the 1D method of characteristics (MOC) and the 3D finite volume method of computational fluid dynamics (CFD). The coupling method is applied to compressible flow in hydraulic systems. The MOC code is implemented as a set of boundary conditions in the OpenFOAM open source CFD software. The coupling is realized by two linear equations originating from the characteristics equation and the Riemann constant equation, respectively. The coupling method is validated using three simple water hammer cases and several coupling configurations. The accuracy and robustness are investigated with respect to the mesh size ratio across the interface, and 3D flow features close to the interface. The method is finally applied to the transient flow caused by the closing and opening of a knife valve (gate) in a pipe, where the flow is driven by the difference in free surface elevation between two tanks. A small region surrounding the moving gate is resolved by CFD, using a dynamic mesh library, while the rest of the system is modeled by MOC. Minor losses are included in the 1D region, corresponding to the contraction of the flow from the upstream tank into the pipe, a separate stationary flow regulation valve, and a pipe bend. The results are validated with experimental data. A 1D solution is provided for comparison, using the static gate characteristics obtained from steady-state CFD simulations.

Research and Development of Ultra-High Strength X100 Welded Pipe

NASA Astrophysics Data System (ADS)

Chuanguo, Zhang; Lei, Zheng; Ping, Hu; Bei, Zhang; Kougen, Wu; Weifeng, Huang

Ultra-high strength X100 welded pipe can be used in the construction of long distance oil and gas pipeline to improve transmission capacity and reduce operation cost. By using the way of thermo-simulation and pilot rolling, the CCT (Continuous Cooling Transformation) diagram and the relationship between ACC (Accelerated Cooling) parameters, microstructure and mechanical properties were studied for the designed X100 pipeline steel with low carbon, high manganese and niobium micro-alloyed composition in lab. The analysis of CCT diagram indicates that the suitable hardness and microstructure can be obtained in the cooling rate of 20 80°C/sec. The pilot rolling results show that the ACC cooling start temperature below Ar3 phase transformation point is beneficial to increase uniform elongation, and the cooling stop temperature of 150 350°C is helpful to obtain high strength and toughness combination. Based on the research conclusions, the X100 plate and UOE pipe with dimension in O.D.1219×W.T.14.8mm, O.D.1219×W.T.17.8mm, designed for the natural gas transmission pipeline, were trial produced. The manufactured pipe body impact absorbed energy at -10°C is over 250J. The DWTT shear area ratio at 0°C is over 85%. The transverse strength meets the X100 grade requirement, and uniform elongation is over 4%. The X100 plate and UOE pipe with dimension in O.D.711×W.T.20.0mm, O.D.711×W.T.12.5mm, designed for an offshore engineering, were also trial produced. The average impact absorbed energy of pipe body at -30°C is over 200J. The average impact absorbed energy of HAZ (Heat-affected zone) and WM (Welded Seam) at -30°C is over 100J. And the good pipe shapes were obtained

Characterization of linear interfacial waves in a turbulent gas-liquid pipe flow

NASA Astrophysics Data System (ADS)

Ayati, A. A.; Farias, P. S. C.; Azevedo, L. F. A.; de Paula, I. B.

2017-06-01

The evolution of interfacial waves on a stratified flow was investigated experimentally for air-water flow in a horizontal pipe. Waves were introduced in the liquid level of stratified flow near the pipe entrance using an oscillating plate. The mean height of liquid layer and the fluctuations superimposed on this mean level were captured using high speed cameras. Digital image processing techniques were used to detect instantaneous interfaces along the pipe. The driving signal of the oscillating plate was controlled by a D/A board that was synchronized with acquisitions. This enabled to perform phase-locked acquisitions and to use ensemble average procedures. Thereby, it was possible to measure the temporal and spatial evolution of the disturbances introduced in the flow. In addition, phase-locked measurements of the velocity field in the liquid layer were performed using standard planar Particle Image Velocimetry (PIV). The velocity fields were extracted at a fixed streamwise location, whereas the measurements of the liquid level were performed at several locations along the pipe. The assessment of the setup was important for validation of the methodology proposed in this work, since it aimed at providing results for further comparisons with theoretical models and numerical simulations. Therefore, the work focuses on validation and characterization of interfacial waves within the linear regime. Results show that under controlled conditions, the wave development can be well captured and reproduced. In addition, linear waves were observed for liquid level oscillations lower than about 1.5% of the pipe diameter. It was not possible to accurately define an amplitude threshold for the appearance of nonlinear effects because it strongly depended on the wave frequency. According to the experimental findings, longer waves display characteristics similar to linear waves, while short ones exhibit a more complex evolution, even for low amplitudes.

Long-Term Behavior of Simulated Partial Lead Service Line Replacements

PubMed Central

St. Clair, Justin; Cartier, Clement; Triantafyllidou, Simoni; Clark, Brandi; Edwards, Marc

2016-01-01

Abstract In this 48-month pilot study, long-term impacts of copper:lead galvanic connections on lead release to water were assessed without confounding differences in pipe exposure prehistory or disturbances arising from cutting lead pipe. Lead release was tracked from three lead service line configurations, including (1) 100% lead, (2) traditional partial replacement with 50% copper upstream of 50% lead, and (3) 50% lead upstream of 50% copper as a function of flow rate, connection types, and sampling methodologies. Elevated lead from galvanic corrosion worsened with time, with 140% more lead release from configurations representing traditional partial replacement configurations at 14 months compared to earlier data in the first 8 months. Even when sampled consistently at moderate flow rate (8 LPM) and collecting all water passing through service lines, conditions representing traditional partial service line configurations were significantly worse (≈40%) when compared to 100% lead pipe. If sampled at a high flow rate (32 LPM) and collecting 2 L samples from service lines, 100% of samples collected from traditional partial replacement configurations exceeded thresholds posing an acute health risk versus a 0% risk for samples from 100% lead pipe. Temporary removal of lead accumulations near Pb:Cu junctions and lead deposits from other downstream plastic pipes reduced risk of partial replacements relative to that observed for 100% lead. When typical brass compression couplings were used to connect prepassivated lead pipes, lead release spiked up to 10 times higher, confirming prior concerns raised at bench and field scale regarding adverse impacts of crevices and service line disturbances on lead release. To quantify semirandom particulate lead release from service lines in future research, whole-house filters have many advantages compared to other approaches. PMID:26989344

Effects of sulfate on heavy metal release from iron corrosion scales in drinking water distribution system.

PubMed

Sun, Huifang; Shi, Baoyou; Yang, Fan; Wang, Dongsheng

2017-05-01

Trace heavy metals accumulated in iron corrosion scales within a drinking water distribution system (DWDS) could potentially be released to bulk water and consequently deteriorate the tap water quality. The objective of this study was to identify and evaluate the release of trace heavy metals in DWDS under changing source water conditions. Experimental pipe loops with different iron corrosion scales were set up to simulate the actual DWDS. The effects of sulfate levels on heavy metal release were systemically investigated. Heavy metal releases of Mn, Ni, Cu, Pb, Cr and As could be rapidly triggered by sulfate addition but the releases slowly decreased over time. Heavy metal release was more severe in pipes transporting groundwater (GW) than in pipes transporting surface water (SW). There were strong positive correlations (R 2  > 0.8) between the releases of Fe and Mn, Fe and Ni, Fe and Cu, and Fe and Pb. When switching to higher sulfate water, iron corrosion scales in all pipe loops tended to be more stable (especially in pipes transporting GW), with a larger proportion of stable constituents (mainly Fe 3 O 4 ) and fewer unstable compounds (β-FeOOH, γ-FeOOH, FeCO 3 and amorphous iron oxides). The main functional iron reducing bacteria (IRB) communities were favorable for the formation of Fe 3 O 4 . The transformation of corrosion scales and the growth of sulfate reducing bacteria (SRB) accounted for the gradually reduced heavy metal release with time. The higher metal release in pipes transporting GW could be due to increased Fe 6 (OH) 12 CO 3 content under higher sulfate concentrations. Copyright © 2017 Elsevier Ltd. All rights reserved.

Assessment of SFR Wire Wrap Simulation Uncertainties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Delchini, Marc-Olivier G.; Popov, Emilian L.; Pointer, William David

Predictive modeling and simulation of nuclear reactor performance and fuel are challenging due to the large number of coupled physical phenomena that must be addressed. Models that will be used for design or operational decisions must be analyzed for uncertainty to ascertain impacts to safety or performance. Rigorous, structured uncertainty analyses are performed by characterizing the model’s input uncertainties and then propagating the uncertainties through the model to estimate output uncertainty. This project is part of the ongoing effort to assess modeling uncertainty in Nek5000 simulations of flow configurations relevant to the advanced reactor applications of the Nuclear Energy Advancedmore » Modeling and Simulation (NEAMS) program. Three geometries are under investigation in these preliminary assessments: a 3-D pipe, a 3-D 7-pin bundle, and a single pin from the Thermal-Hydraulic Out-of-Reactor Safety (THORS) facility. Initial efforts have focused on gaining an understanding of Nek5000 modeling options and integrating Nek5000 with Dakota. These tasks are being accomplished by demonstrating the use of Dakota to assess parametric uncertainties in a simple pipe flow problem. This problem is used to optimize performance of the uncertainty quantification strategy and to estimate computational requirements for assessments of complex geometries. A sensitivity analysis to three turbulent models was conducted for a turbulent flow in a single wire wrapped pin (THOR) geometry. Section 2 briefly describes the software tools used in this study and provides appropriate references. Section 3 presents the coupling interface between Dakota and a computational fluid dynamic (CFD) code (Nek5000 or STARCCM+), with details on the workflow, the scripts used for setting up the run, and the scripts used for post-processing the output files. In Section 4, the meshing methods used to generate the THORS and 7-pin bundle meshes are explained. Sections 5, 6 and 7 present numerical results for the 3-D pipe, the single pin THORS mesh, and the 7-pin bundle mesh, respectively.« less

Applications of a morphological scene change detection (MSCD) for visual leak and failure identification in process and chemical engineering

NASA Astrophysics Data System (ADS)

Tickle, Andrew J.; Harvey, Paul K.; Smith, Jeremy S.

2010-10-01

Morphological Scene Change Detection (MSCD) is a process typically tasked at detecting relevant changes in a guarded environment for security applications. This can be implemented on a Field Programmable Gate Array (FPGA) by a combination of binary differences based around exclusive-OR (XOR) gates, mathematical morphology and a crucial threshold setting. The additional ability to set up the system in virtually any location due to the FPGA makes it ideal for insertion into an autonomous mobile robot for patrol duties. However, security is not the only potential of this robust algorithm. This paper details how such a system can be used for the detection of leaks in piping for use in the process and chemical industries and could be deployed as stated in the above manner. The test substance in this work was water, which was pumped either as a liquid or as low pressure steam through a simple pipe configuration with holes at set points to simulate the leaks. These holes were situated randomly at either the center of a pipe (in order to simulate an impact to it) or at a joint or corner (to simulate a failed weld). Imagery of the resultant leaks, which were visualised as drips or the accumulation of steam, which where analysed using MATLAB to determine their pixel volume in order to calibrate the trigger for the MSCD. The triggering mechanism is adaptive to make it possible in theory for the type of leak to be determined by the number of pixels in the threshold of the image and a numerical output signal to state which of the leak situations is being observed. The system was designed using the DSP Builder package from Altera so that its graphical nature is easily comprehensible to the non-embedded system designer. Furthermore, all the data from the DSP Builder simulation underwent verification against MATLAB comparisons using the image processing toolbox in order to validate the results.

[CFD numerical simulation onto the gas-liquid two-phase flow behavior during vehicle refueling process].

PubMed

Chen, Jia-Qing; Zhang, Nan; Wang, Jin-Hui; Zhu, Ling; Shang, Chao

2011-12-01

With the gradual improvement of environmental regulations, more and more attentions are attracted to the vapor emissions during the process of vehicle refueling. Research onto the vehicle refueling process by means of numerical simulation has been executed abroad since 1990s, while as it has never been involved so far domestically. Through reasonable simplification about the physical system of "Nozzle + filler pipe + gasoline storage tank + vent pipe" for vehicle refueling, and by means of volume of fluid (VOF) model for gas-liquid two-phase flow and Re-Normalization Group kappa-epsilon turbulence flow model provided in commercial computational fluid dynamics (CFD) software Fluent, this paper determined the proper mesh discretization scheme and applied the proper boundary conditions based on the Gambit software, then established the reasonable numerical simulation model for the gas-liquid two-phase flow during the refueling process. Through discussing the influence of refueling velocity on the static pressure of vent space in gasoline tank, the back-flowing phenomenon has been revealed in this paper. It has been demonstrated that, the more the flow rate and the refueling velocity of refueling nozzle is, the higher the gross static pressure in the vent space of gasoline tank. In the meanwhile, the variation of static pressure in the vent space of gasoline tank can be categorized into three obvious stages. When the refueling flow rate becomes higher, the back-flowing phenomenon of liquid gasoline can sometimes be induced in the head section of filler pipe, thus making the gasoline nozzle pre-shut-off. Totally speaking, the theoretical work accomplished in this paper laid some solid foundation for self-researching and self-developing the technology and apparatus for the vehicle refueling and refueling emissions control domestically.

Effect of disinfectant, water age, and pipe material on occurrence and persistence of Legionella, mycobacteria, Pseudomonas aeruginosa, and two amoebas.

PubMed

Wang, Hong; Masters, Sheldon; Hong, Yanjuan; Stallings, Jonathan; Falkinham, Joseph O; Edwards, Marc A; Pruden, Amy

2012-11-06

Opportunistic pathogens represent a unique challenge because they establish and grow within drinking water systems, yet the factors stimulating their proliferation are largely unknown. The purpose of this study was to examine the influence of pipe materials, disinfectant type, and water age on occurrence and persistence of three opportunistic pathogens (Legionella pneumophila, Mycobacterium avium, and Pseudomonas aeruginosa), broader genera (Legionella and mycobacteria), and two amoeba hosts (Acanthamoeba spp. and Hartmanella vermiformis). Triplicate simulated distribution systems (SDSs) compared iron, cement, and PVC pipe materials fed either chlorinated or chloraminated tap water and were sampled at water ages ranging from 1 day to 5.7 days. Quantitative polymerase chain reaction quantified gene copies of target microorganisms in both biofilm and bulk water. Legionella, mycobacteria, P. aeruginosa, and both amoebas naturally colonized the six SDSs, but L. pneumophila and M. avium were not detected. Disinfectant type and dose was observed to have the strongest influence on the microbiota. Disinfectant decay was noted with water age, particularly in chloraminated SDSs (due to nitrification), generally resulting in increased microbial detection frequencies and densities with water age. The influence of pipe material became apparent at water ages corresponding to low disinfectant residual. Each target microbe appeared to display a distinct response to disinfectant type, pipe materials, water age, and their interactions. Differences between the first and the second samplings (e.g., appearance of Legionella, reduction in P. aeruginosa and Acanthamoeba) suggest a temporally dynamic drinking water microbial community.

Insights Gained from Ultrasonic Testing of Piping Welds Subjected to the Mechanical Stress Improvement Process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, Michael T.; Cinson, Anthony D.; Crawford, Susan L.

2010-12-01

Pacific Northwest National Laboratory (PNNL) is assisting the United States Nuclear Regulatory Commission (NRC) in developing a position on the management of primary water stress corrosion cracking (PWSCC) in leak-before-break piping systems. Part of this involves determining whether inspections alone, or inspections plus mitigation, are needed. This work addresses the reliability of ultrasonic testing (UT) of cracks that have been mitigated by the mechanical stress improvement process (MSIP). The MSIP has been approved by the NRC (NUREG-0313) since 1986 and modifies residual stresses remaining after welding with compressive, or neutral, stresses near the inner diameter surface of the pipe. Thismore » compressive stress is thought to arrest existing cracks and inhibit new crack formation. To evaluate the effectiveness of the MSIP and the reliability of ultrasonic inspections, flaws were evaluated both before and after MSIP application. An initial investigation was based on data acquired from cracked areas in 325-mm-diameter piping at the Ignalina Nuclear Power Plant (INPP) in Lithuania. In a follow-on exercise, PNNL acquired and evaluated similar UT data from a dissimilar metal weld (DMW) specimen containing implanted thermal fatigue cracks. The DMW specimen is a carbon steel nozzle-to-safe end-to-stainless steel pipe section that simulates a pressurizer surge nozzle. The flaws were implanted in the nozzle-to-safe end Alloy 82/182 butter region. Results are presented on the effects of MSIP on specimen surfaces, and on UT flaw responses.« less

Control of the micromovements of a composite-material nail design: A finite element analysis.

PubMed

Ben-Or, Mor; Shavit, Ronen; Ben-Tov, Tomer; Salai, Moshe; Steinberg, Ely L

2016-02-01

Intramedullary nail fixation is the most accepted modality for stabilizing long bone midshaft fractures. The commercially used nails are fabricated from Stainless Steel or Titanium. Composite-materials (CM) mainly carbon-fiber reinforced polymers (CFRP) have been gaining more interest and popularity due to their properties, such as modulus of elasticity close to that of bone, increased fatigue strength, and radio-opacity to irradiation that permits a better visualization of the healing process. The use of CFRP instead of metals allows better control of different directional movements along a fracture site. The purpose of this analysis was to design a CM intramedullary nail to enable micromovements as depicted on a finite element analysis method. We designed a three-dimentional femoral nail model. Three CFRP with different laminates arrangements, were included in the analysis. The finite element analysis involved applying vertical and horizontal loads on each of the designed and tested nails. The nails permitted a transverse micromovement of 0.75mm for the 45° lay-up and 1.5mm for the 90° lay-up for the CM, 1.38mm for the Titanium and 0.74mm for the Stainless Steel nails. The recorded axial movements were 0.53mm for the 45° lay-up, 0.87mm for the 90° lay-up, 0.46mm for the unsymmetrical lay-up CM, 0.046 for the Titanium and 0.02 for the Stainless Steel nails. Overall, the simulations showed that nail transverse micromovements can be reduced by using 45° carbon fiber orientations. Similar results were observed with each metal nails. We found that nail micromovements can be controlled by changing the directional stiffness using different lay-up orientations. These results can be useful for predicting nail micromovements under specified loading conditions which are crucial for stimulating callus formation in the early stages of healing. Copyright © 2015 Elsevier Ltd. All rights reserved.

Modeling the Sedimentation of Red Blood Cells in Flow under Strong External Magnetic Body Force using a Lattice Boltzmann Fictitious Domain Method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Xing; Lin, Guang

To model the sedimentation of the red blood cell (RBC) in a square duct and a circular pipe, the recently developed technique derived from the lattice Boltzmann method and the distributed Lagrange multiplier/fictitious domain method (LBM-DLM/FD) is extended to employ the mesoscopic network model for simulations of the sedimentation of the RBC in flow. The flow is simulated by the lattice Boltzmann method with a strong magnetic body force, while the network model is used for modeling RBC deformation. The fluid-RBC interactions are enforced by the Lagrange multiplier. The sedimentation of the RBC in a square duct and a circularmore » pipe is simulated, revealing the capacity of the current method for modeling the sedimentation of RBC in various flows. Numerical results illustrate that that the terminal setting velocity increases with the increment of the exerted body force. The deformation of the RBC has significant effect on the terminal setting velocity due to the change of the frontal area. The larger the exerted force is, the smaller the frontal area and the larger deformation of the RBC are.« less

Numerical Simulation of Pulsation Flow in the Vapour Channel of Short Low Temperature Heat Pipes at High Heat Loads

NASA Astrophysics Data System (ADS)

Seryakov, A. V.; Konkin, A. V.

2017-11-01

The results of the numerical simulation of pulsations in the Laval-liked vapour channel of short low-temperature range heat pipes (HPs) are presented. The numerical results confirmed the experimentally obtained increase of the frequency of pulsations in the vapour channel of short HPs with increasing overheat of the porous evaporator relative to the boiling point of the working fluid. The occurrence of pressure pulsations inside the vapour channel in a short HPs is a complex phenomenon associated with the boiling beginning in the capillary-porous evaporator at high heat loads, and appearance the excess amount of vapour above it, leading to the increase in pressure P to a value at which the boiling point TB of the working fluid becomes higher than the evaporator temperature Tev. Vapour clot spreads through the vapour channel and condense, and then a rarefaction wave return from condenser in the evaporator, the boiling in which is resumed and the next cycle of the pulsations is repeated. Numerical simulation was performed using finite element method implemented in the commercial program ANSYS Multiphisics 14.5 in the two-dimensional setting of axis symmetric moist vapour flow with third kind boundary conditions.

A numerical and experimental investigation of the thermal control performance of a spaceborne compressor assembly

NASA Astrophysics Data System (ADS)

Oh, Hyun-Ung; Lee, Min-Kyu; Shin, Somin; Hong, Joo-Sung

2011-09-01

Spaceborne pulse tube type cryocoolers are widely used for providing cryogenic temperatures for sensitive infrared, gamma-ray and X-ray detectors. Thermal control for the compressor of the cryocooler is one of the important technologies for the cooling performance, mission life time, and jitter stability of the cooler. The thermal design of the compressor assembly proposed in this study is basically composed of a heat pipe, a radiator, and a heater. In the present work, a method for heat pipe implementation is proposed and investigated to ensure the jitter stability of the compressor under the condition that one heat pipe is not working. An optimal design of the radiator that uses ribs for effective use by minimizing the temperature gradient on the radiator and reducing its weight is introduced. The effectiveness of the thermal design of the compressor assembly is demonstrated by on-orbit thermal analysis using the correlated thermal model obtained from the thermal balance test that is performed under a space simulating environment.

Joint physical and numerical modeling of water distribution networks.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zimmerman, Adam; O'Hern, Timothy John; Orear, Leslie Jr.

2009-01-01

This report summarizes the experimental and modeling effort undertaken to understand solute mixing in a water distribution network conducted during the last year of a 3-year project. The experimental effort involves measurement of extent of mixing within different configurations of pipe networks, measurement of dynamic mixing in a single mixing tank, and measurement of dynamic solute mixing in a combined network-tank configuration. High resolution analysis of turbulence mixing is carried out via high speed photography as well as 3D finite-volume based Large Eddy Simulation turbulence models. Macroscopic mixing rules based on flow momentum balance are also explored, and in somemore » cases, implemented in EPANET. A new version EPANET code was developed to yield better mixing predictions. The impact of a storage tank on pipe mixing in a combined pipe-tank network during diurnal fill-and-drain cycles is assessed. Preliminary comparison between dynamic pilot data and EPANET-BAM is also reported.« less

Analysis of the Casson and Carreau-Yasuda non-Newtonian blood models in steady and oscillatory flows using the lattice Boltzmann method

NASA Astrophysics Data System (ADS)

Boyd, Joshua; Buick, James M.; Green, Simon

2007-09-01

The lattice Boltzmann method is modified to allow the simulation of non-Newtonian shear-dependent viscosity models. Casson and Carreau-Yasuda non-Newtonian blood viscosity models are implemented and are used to compare two-dimensional Newtonian and non-Newtonian flows in the context of simple steady flow and oscillatory flow in straight and curved pipe geometries. It is found that compared to analogous Newtonian flows, both the Casson and Carreau-Yasuda flows exhibit significant differences in the steady flow situation. In the straight pipe oscillatory flows, both models exhibit differences in velocity and shear, with the largest differences occurring at low Reynolds and Womersley numbers. Larger differences occur for the Casson model. In the curved pipe Carreau-Yasuda model, moderate differences are observed in the velocities in the central regions of the geometries, and the largest shear rate differences are observed near the geometry walls. These differences may be important for the study of atherosclerotic progression.

Performance of a thermionic converter module utilizing emitter and collector heat pipes

NASA Technical Reports Server (NTRS)

Kroeger, E. W.; Morris, J. F.; Miskolczy, G.; Lieb, D. P.; Goodale, D. B.

1978-01-01

A thermionic converter module simulating a configuration for an out-of-core thermionic nuclear reactor was designed, fabricated, and tested. The module consists of three cylindrical thermionic converters. The tungsten emitter of the converter is heated by a tungsten, lithium heat pipe. The emitter heat pipes are immersed in a furnace, insulated by MULTI-FOIL thermal insulation, and heated by tungsten radiation filaments. The performance of each thermionic converter was characterized before assembly into the module. Dynamic voltage, current curves were taken using a 60 Hz sweep and computerized data acquisition over a range of emitter, collector, and cesium-reservoir temperatures. An output power of 215 W was observed at an emitter temperature of 1750 K and a collector temperature of 855 K for a two diode module. With a three diode module, an output power of 270 W was observed at an average emitter temperature of 1800 K and a Collector temperature of 875 K.

A New Differential Pressure Flow Meter for Measurement of Human Breath Flow: Simulation and Experimental Investigation

PubMed Central

Bridgeman, Devon; Tsow, Francis; Xian, Xiaojun; Forzani, Erica

2016-01-01

The development and performance characterization of a new differential pressure-based flow meter for human breath measurements is presented in this article. The device, called a “Confined Pitot Tube,” is comprised of a pipe with an elliptically shaped expansion cavity located in the pipe center, and an elliptical disk inside the expansion cavity. The elliptical disk, named Pitot Tube, is exchangeable, and has different diameters, which are smaller than the diameter of the elliptical cavity. The gap between the disk and the cavity allows the flow of human breath to pass through. The disk causes an obstruction in the flow inside the pipe, but the elliptical cavity provides an expansion for the flow to circulate around the disk, decreasing the overall flow resistance. We characterize the new sensor flow experimentally and theoretically, using Comsol Multiphysics® software with laminar and turbulent models. We also validate the sensor, using inhalation and exhalation tests and a reference method. PMID:27818521

Experimental and Numerical Investigation of Local Scour Around Submarine Piggyback Pipeline Under Steady Current

NASA Astrophysics Data System (ADS)

Zhao, Enjin; Shi, Bing; Qu, Ke; Dong, Wenbin; Zhang, Jing

2018-04-01

As a new type of submarine pipeline, the piggyback pipeline has been gradually adopted in engineering practice to enhance the performance and safety of submarine pipelines. However, limited simulation work and few experimental studies have been published on the scour around the piggyback pipeline under steady current. This study numerically and experimentally investigates the local scour of the piggyback pipe under steady current. The influence of prominent factors such as pipe diameter, inflow Reynolds number, and gap between the main and small pipes, on the maximum scour depth have been examined and discussed in detail. Furthermore, one formula to predict the maximum scour depth under the piggyback pipeline has been derived based on the theoretical analysis of scour equilibrium. The feasibility of the proposed formula has been effectively calibrated by both experimental data and numerical results. The findings drawn from this study are instructive in the future design and application of the piggyback pipeline.

Computational compliance criteria in water hammer modelling

NASA Astrophysics Data System (ADS)

Urbanowicz, Kamil

2017-10-01

Among many numerical methods (finite: difference, element, volume etc.) used to solve the system of partial differential equations describing unsteady pipe flow, the method of characteristics (MOC) is most appreciated. With its help, it is possible to examine the effect of numerical discretisation carried over the pipe length. It was noticed, based on the tests performed in this study, that convergence of the calculation results occurred on a rectangular grid with the division of each pipe of the analysed system into at least 10 elements. Therefore, it is advisable to introduce computational compliance criteria (CCC), which will be responsible for optimal discretisation of the examined system. The results of this study, based on the assumption of various values of the Courant-Friedrichs-Levy (CFL) number, indicate also that the CFL number should be equal to one for optimum computational results. Application of the CCC criterion to own written and commercial computer programmes based on the method of characteristics will guarantee fast simulations and the necessary computational coherence.

Response of reinforced concrete and corrugated steel pipes to surface load

NASA Astrophysics Data System (ADS)

Lay, Geoff R.

Full-scale simulated live load tests were conducted in a controlled laboratory setting using a single-axle frame on 600-mm-inner-diameter reinforced concrete pipe (RCP) and corrugated steel pipe (CSP) when buried in dense, well-graded sand and gravel. Measurements of the RCP at nominal and working forces and beyond are reported for 0.3, 0.6 and 0.9 m of soil cover above the pipe crown. The RCP experienced no cracking when buried at 0.3 m under nominal and working CL-625 and CL-800 single-axle design loads. At these loads, the vertical contraction of the pipe diameter was less than 0.08 and 0.10 mm and the largest tensile strains in the pipe were 75 and 100 muepsilon (50-60% of the cracking strain), respectively. A 0.15 (+/-0.05)-mm-wide axial crack developed at the inner crown in the presence of a 6 kNm/m circumferential bending moment (70% of the theoretical ultimate moment capacity) at the fully factored CL-625 load. This crack did not propagate or widen from 3 series of cyclic load-unload tests. At 1300 kN of applied load the change in pipe diameter was less than 3.5 mm. Increasing soil cover from 0.3 to 0.6 to 0.9 m reduced the circumferential crown bending moment from 6.0 to 3.9 to 2.1 kNm/m, respectively, at 400 kN of axle load. A 1.6- and a 2.8-mm-thick CSP were also subjected to axle loading. No yielding or limit states occurred in the 1.6-mm-thick CSP when buried 0.9-m-deep. However, at 0.6 m of cover a 300 kN axle load caused local yielding at the pipe crown. Increasing soil cover from 0.6 to 0.9 m decreased the vertical diameter change from -3.0 to -1.2 mm and the crown bending moment from 0.7 to 0.2 kNm/m (75% and 20% of the yield moment), respectively, at a 250 kN axle load. Deflections of the thicker CSP were less than the thinner pipe below the CL-625 single-axle load, however further increases in applied load produced a greater response in the thicker pipe, likely due to a haunch support issue. Shallow axle loading produced a greater 3-dimensional response and a larger bending effect in both CSPs.

Nuclear Power Plant Mechanical Component Flooding Fragility Experiments Status

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pope, C. L.; Savage, B.; Johnson, B.

This report describes progress on Nuclear Power Plant mechanical component flooding fragility experiments and supporting research. The progress includes execution of full scale fragility experiments using hollow-core doors, design of improvements to the Portal Evaluation Tank, equipment procurement and initial installation of PET improvements, designation of experiments exploiting the improved PET capabilities, fragility mathematical model development, Smoothed Particle Hydrodynamic simulations, wave impact simulation device research, and pipe rupture mechanics research.

Modeling Flue Pipes: Subsonic Flow, Lattice Boltzmann, and Parallel Distributed Computers.

DTIC Science & Technology

1995-01-01

Abstract The problem of simulating the hydrodynamics and the acoustic waves inside wind musical instruments such as the recorder, the organ, and the ute...inside wind musical instruments such as the recorder, the organ, and the ute is considered. The problem is attacked by developing suitable local...applications such as the simulation of uid dynamics inside wind musical instruments. In the past, he has also worked on numerical methods for ordinary di

Helium refrigeration system for hydrogen liquefaction applications

NASA Astrophysics Data System (ADS)

Nair, J. Kumar, Sr.; Menon, RS; Goyal, M.; Ansari, NA; Chakravarty, A.; Joemon, V.

2017-02-01

Liquid hydrogen around 20 K is used as cold moderator for generating “cold neutron beam” in nuclear research reactors. A cryogenic helium refrigeration system is the core upon which such hydrogen liquefaction applications are built. A thermodynamic process based on reversed Brayton cycle with two stage expansion using high speed cryogenic turboexpanders (TEX) along with a pair of compact high effectiveness process heat exchangers (HX), is well suited for such applications. An existing helium refrigeration system, which had earlier demonstrated a refrigeration capacity of 470 W at around 20 K, is modified based on past operational experiences and newer application requirements. Modifications include addition of a new heat exchanger to simulate cryogenic process load and two other heat exchangers for controlling the temperatures of helium streams leading out to the application system. To incorporate these changes, cryogenic piping inside the cold box is suitably modified. This paper presents process simulation, sizing of new heat exchangers as well as fabrication aspects of the modified cryogenic process piping.

On the thermal runaway of combustible fluids in lagging material

NASA Astrophysics Data System (ADS)

McIntosh, A. C.; Griffiths, J. F.

1995-01-01

This paper presents the mathematical foundations for a simple theory for investigating the phenomenon of ignition of flammable fluids in lagging material that are used for insulation of hot pipework, for transport of heat transfer fluids, or other similar situations. Experiments with porous material impregnated with a flammable fluid have simulated the self-heating known to occur when combustible liquids leak from a hot pipe into lagging surrounding the pipe or are split from another source on to the lagging. A theory to explain these findings is presented which shows that there is a watershed temperature beyond which substantial self-heating will take place. Although the theory does not take account of diffusion, it simulates the main physics of the phenomenon-that is, combustible fluid, which normally in the open air would evaporate and not be a hazard, can, within a porous medium, remain dispersed within the porous structure long enough for the exothermic oxidation to develop into ignition.

Egg laying sequence influences egg mercury concentrations and egg size in three bird species: Implications for contaminant monitoring programs

USGS Publications Warehouse

Ackerman, Joshua T.; Eagles-Smith, Collin A.; Herzog, Mark P.; Yee, Julie L.; Hartman, C. Alex

2016-01-01

Bird eggs are commonly used in contaminant monitoring programs and toxicological risk assessments, but intra-clutch variation and sampling methodology could influence interpretability. We examined the influence of egg laying sequence on egg mercury concentrations and burdens in American avocets, black-necked stilts, and Forster's terns. The average decline in mercury concentrations between the first and last egg laid was 33% for stilts, 22% for terns, and 11% for avocets, and most of this decline occurred between the first and second eggs laid (24% for stilts, 18% for terns, and 9% for avocets). Trends in egg size with egg laying order were inconsistent among species and overall differences in egg volume, mass, length, and width were <3%. We summarized the literature and, among 17 species studied, mercury concentrations generally declined by 16% between the first and second eggs laid. Despite the strong effect of egg laying sequence, most of the variance in egg mercury concentrations still occurred among clutches (75%-91%) rather than within clutches (9%-25%). Using simulations, we determined that to accurately estimate a population's mean egg mercury concentration using only a single random egg from a subset of nests, it would require sampling >60 nests to represent a large population (10% accuracy) or ≥14 nests to represent a small colony that contained <100 nests (20% accuracy).

Numerical study of heat and mass transfer in inertial suspensions in pipes.

NASA Astrophysics Data System (ADS)

Niazi Ardekani, Mehdi; Brandt, Luca

2017-11-01

Controlling heat and mass transfer in particulate suspensions has many important applications such as packed and fluidized bed reactors and industrial dryers. In this work, we study the heat and mass transfer within a suspension of spherical particles in a laminar pipe flow, using the immersed boundary method (IBM) to account for the solid fluid interactions and a volume of fluid (VoF) method to resolve temperature equation both inside and outside of the particles. Tracers that follow the fluid streamlines are considered to investigate mass transfer within the suspension. Different particle volume fractions 5, 15, 30 and 40% are simulated for different pipe to particle diameter ratios: 5, 10 and 15. The preliminary results quantify the heat and mass transfer enhancement with respect to a single-phase laminar pipe flow. We show in particular that the heat transfer from the wall saturates for volume fractions more than 30%, however at high particle Reynolds numbers (small diameter ratios) the heat transfer continues to increase. Regarding the dispersion of tracer particles we show that the diffusivity of tracers increases with volume fraction in radial and stream-wise directions however it goes through a peak at 15% in the azimuthal direction. European Research Council, Grant No. ERC-2013-CoG- 616186, TRITOS; SNIC (the Swedish National Infrastructure for Computing).

Unitized Regenerative Fuel Cell System Gas Storage/Radiator Development

NASA Technical Reports Server (NTRS)

Jakupca, Ian; Burke, Kenneth A.

2003-01-01

The ancillary components for Unitized Regenerative Fuel Cell (URFC) Energy Storage System are being developed at the NASA Glenn Research Center. This URFC system is unique in that it uses the surface area of the hydrogen and oxygen storage tanks as radiating heat surfaces for overall thermal control of the system. The waste heat generated by the URFC stack during charging and discharging is transferred from the cell stack to the surface of each tank by loop heat pipes. The heat pipes are coiled around each tank and covered with a thin layer of thermally conductive layer of carbon composite. The thin layer of carbon composite acts as a fin structure that spreads the heat away from the heat pipe and across the entire tank surface. Two different sized commercial grade composite tanks were constructed with integral heat pipes and tested in a thermal vacuum chamber to examine the feasibility of using the storage tanks as system radiators. The storage radiators were subjected to different steady-state heat loads and varying heat load profiles. The surface emissivity and specific heat capacity of each tank were calculated. The results were incorporated into a model that simulates the performance of similar radiators using lightweight, space rated carbon composite tanks.

Acoustic attenuation, phase and group velocities in liquid-filled pipes II: simulation for Spallation Neutron Sources and planetary exploration.

PubMed

Jiang, Jian; Baik, Kyungmin; Leighton, Timothy G

2011-08-01

This paper uses a finite element method (FEM) to compare predictions of the attenuation and sound speeds of acoustic modes in a fluid-filled pipe with those of the analytical model presented in the first paper in this series. It explains why, when the predictions of the earlier paper were compared with experimental data from a water-filled PMMA pipe, the uncertainties and agreement for attenuation data were worse than those for sound speed data. Having validated the FEM approach in this way, the versatility of FEM is thereafter demonstrated by modeling two practical applications which are beyond the analysis of the earlier paper. These applications model propagation in the mercury-filled steel pipework of the Spallation Neutron Source at the Oak Ridge National Laboratory (Tennessee), and in a long-standing design for acoustic sensors for use on planetary probes. The results show that strong coupling between the fluid and the solid walls means that erroneous interpretations are made of the data if they assume that the sound speed and attenuation in the fluid in the pipe are the same as those that would be measured in an infinite volume of identical fluid, assumptions which are common when such data have previously been interpreted.

The effect of reduced gravity on cryogenic nitrogen boiling and pipe chilldown.

PubMed

Darr, Samuel; Dong, Jun; Glikin, Neil; Hartwig, Jason; Majumdar, Alok; Leclair, Andre; Chung, Jacob

2016-01-01

Manned deep space exploration will require cryogenic in-space propulsion. Yet, accurate prediction of cryogenic pipe flow boiling heat transfer is lacking, due to the absence of a cohesive reduced gravity data set covering the expected flow and thermodynamic parameter ranges needed to validate cryogenic two-phase heat transfer models. This work provides a wide range of cryogenic chilldown data aboard an aircraft flying parabolic trajectories to simulate reduced gravity. Liquid nitrogen is used to quench a 1.27 cm diameter tube from room temperature. The pressure, temperature, flow rate, and inlet conditions are reported from 10 tests covering liquid Reynolds number from 2,000 to 80,000 and pressures from 80 to 810 kPa. Corresponding terrestrial gravity tests were performed in upward, downward, and horizontal flow configurations to identify gravity and flow direction effects on chilldown. Film boiling heat transfer was lessened by up to 25% in reduced gravity, resulting in longer time and more liquid to quench the pipe to liquid temperatures. Heat transfer was enhanced by increasing the flow rate, and differences between reduced and terrestrial gravity diminished at high flow rates. The new data set will enable the development of accurate and robust heat transfer models of cryogenic pipe chilldown in reduced gravity.

Friction factor and heat transfer of nanofluids containing cylindrical nanoparticles in laminar pipe flow

NASA Astrophysics Data System (ADS)

Lin, Jianzhong; Xia, Yi; Ku, Xiaoke

2014-10-01

Numerical simulations of polyalphaolefins-Al2O3 nanofluids containing cylindrical nanoparticles in a laminar pipe flow are performed by solving the Navier-Stokes equation with term of cylindrical nanoparticles, the general dynamic equation for cylindrical nanoparticles, and equation for nanoparticle orientation. The distributions of particle number and volume concentration, the friction factor, and heat transfer are obtained and analyzed. The results show that distributions of nanoparticle number and volume concentration are non-uniform across the section, with larger and smaller values in the region near the pipe center and near the wall, respectively. The non-uniformity becomes significant with the increase in the axial distance from the inlet. The friction factor decreases with increasing Reynolds number. The relationships between the friction factor and the nanoparticle volume concentration as well as particle aspect ratio are dependent on the Reynolds number. The Nusselt number of nanofluids, directly proportional to the Reynolds number, particle volume concentration, and particle aspect ratio, is higher near the pipe entrance than at the downstream locations. The rate of increase in Nusselt number at lower particle volume concentration is more than that at higher concentration. Finally, the expressions of friction factor and Nusselt number as a function of particle volume concentration, particle aspect ratio, and Reynolds number are derived based on the numerical data.

Numerical and Experimental Investigation of Stratified Gas-Liquid Two-Phase Flow in Horizontal Circular Pipes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Faccini, J.L.H.; Sampaio, P.A.B. de; Su, J.

This paper reports numerical and experimental investigation of stratified gas-liquid two-phase flow in horizontal circular pipes. The Reynolds averaged Navier Stokes equations (RANS) with the k-{omega} model for a fully developed stratified gas-liquid two-phase flow are solved by using the finite element method. A smooth and horizontal interface surface is assumed without considering the interfacial waves. The continuity of the shear stress across the interface is enforced with the continuity of the velocity being automatically satisfied by the variational formulation. For each given interface position and longitudinal pressure gradient, an inner iteration loop runs to solve the nonlinear equations. Themore » Newton-Raphson scheme is used to solve the transcendental equations by an outer iteration to determine the interface position and pressure gradient for a given pair of volumetric flow rates. The interface position in a 51.2 mm ID circular pipe was measured experimentally by the ultrasonic pulse-echo technique. The numerical results were also compared with experimental results in a 21 mm ID circular pipe reported by Masala [1]. The good agreement between the numerical and experimental results indicates that the k-{omega} model can be applied for the numerical simulation of stratified gas-liquid two-phase flow. (authors)« less

In-Line Ultrasonic Monitoring for Sediments Stuck on Inner Wall of a Polyvinyl Chloride Pipe

PubMed Central

2014-01-01

This research verified the applicability and effectiveness of the ultrasonic monitoring of sediments stuck on the inner wall of polyvinyl chloride (PVC) pipes. For identifying the transmittance of acoustic energy and the speed of sound in the PVC material, the pulse-echo ultrasonic testing was conducted for PVC sheets of different thicknesses. To simulate the solidified sediment, the hot melt adhesive (HMA) was covered on the inner wall of the PVC pipe in different heights. From the experiment, the speeds of sound in the PVC and the HMA materials were obtained as about 2258 and 2000 m/s, respectively. The thickness of the materials was calculated through the signal processing such as taking the absolute value and low pass filtering, the echo detection, and the measurement of the time of flight. The errors between actual and measured thicknesses of PVC sheets were below 5%. In the case of the substance stuck on the inner wall, the errors were below 2.5%. Since the pulse-echo ultrasonic inspection is available on the outer surface and its measurement accuracy was over 95%, it can be an efficient and effective in-service structural health monitoring for the sediment on the wall of PVC pipes. PMID:25243223

The effect of reduced gravity on cryogenic nitrogen boiling and pipe chilldown

PubMed Central

Darr, Samuel; Dong, Jun; Glikin, Neil; Hartwig, Jason; Majumdar, Alok; Leclair, Andre; Chung, Jacob

2016-01-01

Manned deep space exploration will require cryogenic in-space propulsion. Yet, accurate prediction of cryogenic pipe flow boiling heat transfer is lacking, due to the absence of a cohesive reduced gravity data set covering the expected flow and thermodynamic parameter ranges needed to validate cryogenic two-phase heat transfer models. This work provides a wide range of cryogenic chilldown data aboard an aircraft flying parabolic trajectories to simulate reduced gravity. Liquid nitrogen is used to quench a 1.27 cm diameter tube from room temperature. The pressure, temperature, flow rate, and inlet conditions are reported from 10 tests covering liquid Reynolds number from 2,000 to 80,000 and pressures from 80 to 810 kPa. Corresponding terrestrial gravity tests were performed in upward, downward, and horizontal flow configurations to identify gravity and flow direction effects on chilldown. Film boiling heat transfer was lessened by up to 25% in reduced gravity, resulting in longer time and more liquid to quench the pipe to liquid temperatures. Heat transfer was enhanced by increasing the flow rate, and differences between reduced and terrestrial gravity diminished at high flow rates. The new data set will enable the development of accurate and robust heat transfer models of cryogenic pipe chilldown in reduced gravity. PMID:28725740

Modifications to the Conduit Flow Process Mode 2 for MODFLOW-2005

USGS Publications Warehouse

Reimann, T.; Birk, S.; Rehrl, C.; Shoemaker, W.B.

2012-01-01

As a result of rock dissolution processes, karst aquifers exhibit highly conductive features such as caves and conduits. Within these structures, groundwater flow can become turbulent and therefore be described by nonlinear gradient functions. Some numerical groundwater flow models explicitly account for pipe hydraulics by coupling the continuum model with a pipe network that represents the conduit system. In contrast, the Conduit Flow Process Mode 2 (CFPM2) for MODFLOW-2005 approximates turbulent flow by reducing the hydraulic conductivity within the existing linear head gradient of the MODFLOW continuum model. This approach reduces the practical as well as numerical efforts for simulating turbulence. The original formulation was for large pore aquifers where the onset of turbulence is at low Reynolds numbers (1 to 100) and not for conduits or pipes. In addition, the existing code requires multiple time steps for convergence due to iterative adjustment of the hydraulic conductivity. Modifications to the existing CFPM2 were made by implementing a generalized power function with a user-defined exponent. This allows for matching turbulence in porous media or pipes and eliminates the time steps required for iterative adjustment of hydraulic conductivity. The modified CFPM2 successfully replicated simple benchmark test problems. ?? 2011 The Author(s). Ground Water ?? 2011, National Ground Water Association.

Experimental evidence of symmetry-breaking supercritical transition in pipe flow of shear-thinning fluids

NASA Astrophysics Data System (ADS)

Wen, Chaofan; Poole, Robert J.; Willis, Ashley P.; Dennis, David J. C.

2017-03-01

Experimental results reveal that the asymmetric flow of shear-thinning fluid through a cylindrical pipe, which was previously associated with the laminar-turbulent transition process, appears to have the characteristics of a nonhysteretic, supercritical instability of the laminar base state. Contrary to what was previously believed, classical transition is found to be responsible for returning symmetry to the flow. An absence of evidence of the instability in simulations (either linear or nonlinear) suggests that an element of physics is lacking in the commonly used rheological model for inelastic shear-thinning fluids. These unexpected discoveries raise new questions regarding the stability of these practically important fluids and how they can be successfully modeled.

Natural gas pipeline leak detector based on NIR diode laser absorption spectroscopy.

PubMed

Gao, Xiaoming; Fan, Hong; Huang, Teng; Wang, Xia; Bao, Jian; Li, Xiaoyun; Huang, Wei; Zhang, Weijun

2006-09-01

The paper reports on the development of an integrated natural gas pipeline leak detector based on diode laser absorption spectroscopy. The detector transmits a 1.653 microm DFB diode laser with 10 mW and detects a fraction of the backscatter reflected from the topographic targets. To eliminate the effect of topographic scatter targets, a ratio detection technique was used. Wavelength modulation and harmonic detection were used to improve the detection sensitivity. The experimental detection limit is 50 ppmm, remote detection for a distance up to 20 m away topographic scatter target is demonstrated. Using a known simulative leak pipe, minimum detectable pipe leak flux is less than 10 ml/min.

How do national cultures influence lay people's preferences toward doctors' style of communication? A comparison of 35 focus groups from an European cross national research.

PubMed

Rimondini, Michela; Mazzi, Maria Angela; Deveugele, Myriam; Bensing, Jozien M

2015-12-14

The evidence that inspires and fosters communication skills, teaching programmes and clinical recommendations are often based on national studies which assume, implicitly, that patients' preferences towards doctors' communication style are not significantly affected by their cultural background. The cross-cultural validity of national results has been recognized as a potential limitation on how generally applicable they are in a wider context. Using 35 country-specific focus group discussions from four European countries, the aim of the present study is to test whether or not national cultures influence lay people's preferences towards doctors' style of communication. Lay people preferences on doctor's communication style have been collected in Belgium, the Netherlands, the United Kingdom and Italy. Each centre organized between eight and nine focus groups, where participants (n = 259) were asked to comment on a video of a simulated medical interview. The discussions were audiotaped, transcribed and coded using a common framework (Guliver Coding System) that allowed for the identification of different themes. The frequency distribution of the topics discussed highlights lay people's generally positive views towards most part of doctors interventions. The regression model applied to the Guliver categories highlighted slight national differences and the existence of a cross-cultural appreciation, in particular, of five types of intervention: Doctors attitudes (both Task-Oriented and Affective/Emotional), Summarizing, Structuring and Providing solution. Lay panels valued doctors' communication style in a similar manner in the countries selected. This highlights the existence of a common background, which in the process of internationalization of heath care, might foster the implementation of cross-national teaching programmes and clinical guidelines.

Effects of air velocity on laying hen production from 24 to 27 weeks under simulated evaporatively cooled conditions

USDA-ARS?s Scientific Manuscript database

Thermal conditions play a major role in production efficiency in commercial poultry production. Mitigation of thermal stress can improve productivity, but must be achieved economically. Weather and system design can limit effectiveness of evaporative cooling and increased air movement has been sho...

The large scale microelectronics Computer-Aided Design and Test (CADAT) system

NASA Technical Reports Server (NTRS)

Gould, J. M.

1978-01-01

The CADAT system consists of a number of computer programs written in FORTRAN that provide the capability to simulate, lay out, analyze, and create the artwork for large scale microelectronics. The function of each software component of the system is described with references to specific documentation for each software component.

Composite materials: A compilation

NASA Technical Reports Server (NTRS)

1976-01-01

Design, analysis and fabrication techniques for boron-aluminum composite-structure technology is presented and a new method of joining different laminated composites without mechanical fasteners is proposed. Also discussed is a low-cost procedure for rigidifying expanded honeycomb tubing and piping simulations. A brief note on patent information is added.

Problems with the random number generator RANF implemented on the CDC cyber 205

NASA Astrophysics Data System (ADS)

Kalle, Claus; Wansleben, Stephan

1984-10-01

We show that using RANF may lead to wrong results when lattice models are simulated by Monte Carlo methods. We present a shift-register sequence random number generator which generates two random numbers per cycle on a two pipe CDC Cyber 205.

Investigations on Thermal Conductivities of Jute and Banana Fiber Reinforced Epoxy Composites

NASA Astrophysics Data System (ADS)

Pujari, Satish; Ramakrishna, Avasarala; Balaram Padal, Korabu Tulasi

2017-04-01

The Jute and Banana fibers are used as reinforcement in epoxy resin matrix for making partially green biodegradable material composite via hand lay-up technique. The thermal conductivity of the jute fiber epoxy composites and banana fiber epoxy composites at different volume fraction of the fiber is determined experimentally by using guarded heat flow meter method. The experimental results had shown that thermal conductivity of the composites decrease with an increase in the fiber content. Experimental results are compared with theoretical models (Series model, Hashin model and Maxwell model) to describe the variation of the thermal conductivity versus the volume fraction of the fiber. Good agreement between theoretical and experimental results is observed. Thermal conductivity of Banana fiber composite is less when compared to that of Jute composite which indicates banana is a good insulator and also the developed composites can be used as insulating materials in building, automotive industry and in steam pipes to save energy by reducing rate of heat transfer.

Accurate Simulation of Acoustic Emission Sources in Composite Plates

NASA Technical Reports Server (NTRS)

Prosser, W. H.; Gorman, M. R.

1994-01-01

Acoustic emission (AE) signals propagate as the extensional and flexural plate modes in thin composite plates and plate-like geometries such as shells, pipes, and tubes. The relative amplitude of the two modes depends on the directionality of the source motion. For source motions with large out-of-plane components such as delaminations or particle impact, the flexural or bending plate mode dominates the AE signal with only a small extensional mode detected. A signal from such a source is well simulated with the standard pencil lead break (Hsu-Neilsen source) on the surface of the plate. For other sources such as matrix cracking or fiber breakage in which the source motion is primarily in-plane, the resulting AE signal has a large extensional mode component with little or no flexural mode observed. Signals from these type sources can also be simulated with pencil lead breaks. However, the lead must be fractured on the edge of the plate to generate an in-plane source motion rather than on the surface of the plate. In many applications such as testing of pressure vessels and piping or aircraft structures, a free edge is either not available or not in a desired location for simulation of in-plane type sources. In this research, a method was developed which allows the simulation of AE signals with a predominant extensional mode component in composite plates requiring access to only the surface of the plate.

Assessment of the Partially Resolved Numerical Simulation (PRNS) Approach in the National Combustion Code (NCC) for Turbulent Nonreacting and Reacting Flows

NASA Technical Reports Server (NTRS)

Shih, Tsan-Hsing; Liu, Nan-Suey

2008-01-01

This paper describes an approach which aims at bridging the gap between the traditional Reynolds-averaged Navier-Stokes (RANS) approach and the traditional large eddy simulation (LES) approach. It has the characteristics of the very large eddy simulation (VLES) and we call this approach the partially-resolved numerical simulation (PRNS). Systematic simulations using the National Combustion Code (NCC) have been carried out for fully developed turbulent pipe flows at different Reynolds numbers to evaluate the PRNS approach. Also presented are the sample results of two demonstration cases: nonreacting flow in a single injector flame tube and reacting flow in a Lean Direct Injection (LDI) hydrogen combustor.

See Also:Mechanics of Cohesive-frictional MaterialsCopyright © 2004 John Wiley & Sons, Ltd.Get Sample Copy