WorldWideScience

Sample records for turbine disk cavities

  1. Experimental investigation of turbine disk cavity aerodynamics and heat transfer

    Science.gov (United States)

    Daniels, W. A.; Johnson, B. V.

    1993-01-01

    An experimental investigation of turbine disk cavity aerodynamics and heat transfer was conducted to provide an experimental data base that can guide the aerodynamic and thermal design of turbine disks and blade attachments for flow conditions and geometries simulating those of the space shuttle main engine (SSME) turbopump drive turbines. Experiments were conducted to define the nature of the aerodynamics and heat transfer of the flow within the disk cavities and blade attachments of a large scale model simulating the SSME turbopump drive turbines. These experiments include flow between the main gas path and the disk cavities, flow within the disk cavities, and leakage flows through the blade attachments and labyrinth seals. Air was used to simulate the combustion products in the gas path. Air and carbon dioxide were used to simulate the coolants injected at three locations in the disk cavities. Trace amounts of carbon dioxide were used to determine the source of the gas at selected locations on the rotors, the cavity walls, and the interstage seal. The measurements on the rotor and stationary walls in the forward and aft cavities showed that the coolant effectiveness was 90 percent or greater when the coolant flow rate was greater than the local free disk entrainment flow rate and when room temperature air was used as both coolant and gas path fluid. When a coolant-to-gas-path density ratio of 1.51 was used in the aft cavity, the coolant effectiveness on the rotor was also 90 percent or greater at the aforementioned condition. However, the coolant concentration on the stationary wall was 60 to 80 percent at the aforementioned condition indicating a more rapid mixing of the coolant and flow through the rotor shank passages. This increased mixing rate was attributed to the destabilizing effects of the adverse density gradients.

  2. Flow and heat transfer in gas turbine disk cavities subject to nonuniform external pressure field

    Energy Technology Data Exchange (ETDEWEB)

    Roy, R.P.; Kim, Y.W.; Tong, T.W. [Arizona State Univ., Tempe, AZ (United States)

    1995-10-01

    Injestion of hot gas from the main-stream gas path into turbine disk cavities, particularly the first-stage disk cavity, has become a serious concern for the next-generation industrial gas turbines featuring high rotor inlet temperature. Fluid temperature in the cavities increases further due to windage generated by fluid drag at the rotating and stationary surfaces. The resulting problem of rotor disk heat-up is exacerbated by the high disk rim temperature due to adverse (relatively flat) temperature profile of the mainstream gas in the annular flow passage of the turbine. A designer is concerned about the level of stresses in the turbine rotor disk and its durability, both of which are affected significantly by the disk temperature distribution. This distribution also plays a major role in the radial position of the blade tip and thus, in establishing the clearance between the tip and the shroud. To counteract mainstream gas ingestion as well as to cool the rotor and the stator disks, it is necessary to inject cooling air (bled from the compressor discharge) into the wheel space. Since this bleeding of compressor air imposes a penalty on the engine cycle performance, the designers of disk cavity cooling and sealing systems need to accomplish these tasks with the minimum possible amount of bleed air without risking disk failure. This requires detailed knowledge of the flow characteristics and convective heat transfer in the cavity. The flow in the wheel space between the rotor and stator disks is quite complex. It is usually turbulent and contains recirculation regions. Instabilities such as vortices oscillating in space have been observed in the flow. It becomes necessary to obtain both a qualitative understanding of the general pattern of the fluid motion as well as a quantitative map of the velocity and pressure fields.

  3. CO Gas Inside the Protoplanetary Disk Cavity in HD 142527: Disk Structure from ALMA

    OpenAIRE

    Perez, S.; Casassus, S.; Ménard, F.; Roman, P.; van der Plas, G.; Cieza, L.; Pinte, C.; Christiaens, Valentin; Hales, A. S.

    2014-01-01

    Inner cavities and annular gaps in circumstellar disks are possible signposts of giant planet formation. The young star HD 142527 hosts a massive protoplanetary disk with a large cavity that extends up to 140 AU from the central star, as seen in continuum images at infrared and millimeter wavelengths. Estimates of the survival of gas inside disk cavities are needed to discriminate between clearing scenarios. We present a spatially and spectrally resolved carbon monoxide isotopologue 2-1 line ...

  4. RESOLVED IMAGES OF LARGE CAVITIES IN PROTOPLANETARY TRANSITION DISKS

    International Nuclear Information System (INIS)

    Andrews, Sean M.; Wilner, David J.; Espaillat, Catherine; Qi Chunhua; Brown, J. M.; Hughes, A. M.; Dullemond, C. P.; McClure, M. K.

    2011-01-01

    Circumstellar disks are thought to experience a rapid 'transition' phase in their evolution that can have a considerable impact on the formation and early development of planetary systems. We present new and archival high angular resolution (0.''3 ∼ 40-75 AU) Submillimeter Array (SMA) observations of the 880 μm (340 GHz) dust continuum emission from 12 such transition disks in nearby star-forming regions. In each case, we directly resolve a dust-depleted disk cavity around the central star. Using two-dimensional Monte Carlo radiative transfer calculations, we interpret these dust disk structures in a homogeneous, parametric model framework by reproducing their SMA continuum visibilities and spectral energy distributions. The cavities in these disks are large (R cav = 15-73 AU) and substantially depleted of small (∼μm-sized) dust grains, although their mass contents are still uncertain. The structures of the remnant material at larger radii are comparable to normal disks. We demonstrate that these large cavities are relatively common among the millimeter-bright disk population, comprising at least 1 in 5 (20%) of the disks in the bright half (and ≥26% of the upper quartile) of the millimeter luminosity (disk mass) distribution. Utilizing these results, we assess some of the physical mechanisms proposed to account for transition disk structures. As has been shown before, photoevaporation models do not produce the large cavity sizes, accretion rates, and disk masses representative of this sample. A sufficient decrease of the dust optical depths in these cavities by particle growth would be difficult to achieve: substantial growth (to meter sizes or beyond) must occur in large (tens of AU) regions of low turbulence without also producing an abundance of small particles. Given those challenges, we suggest instead that the observations are most commensurate with dynamical clearing due to tidal interactions with low-mass companions-very young (∼1 Myr) brown

  5. Adaptor assembly for coupling turbine blades to rotor disks

    Science.gov (United States)

    Garcia-Crespo, Andres Jose; Delvaux, John McConnell

    2014-09-23

    An adaptor assembly for coupling a blade root of a turbine blade to a root slot of a rotor disk is described. The adaptor assembly includes a turbine blade having a blade root and an adaptor body having an adaptor root. The adaptor body defines a slot having an open end configured to receive the blade root of the turbine blade such that the adaptor root of the adaptor body and the blade root of the turbine blade are adjacent to one another when the blade root of the turbine blade is positioned within the slot. Both the adaptor root of the adaptor body and the blade root of the turbine blade are configured to be received within the root slot of the rotor disk.

  6. Development of drag disk and turbines at the INEL

    International Nuclear Information System (INIS)

    Goodrich, L.D.; Edson, J.L.; Averill, R.H.

    1984-01-01

    One of the parameters that must be measured in nuclear safety research is mass flow rate. The reactor environment associated with two-phase flow makes this measurement difficult. To accomplish this at the Idaho National Engineering Laboratory, a drag disk and turbine transducer conbination was developed. These transducers can withstand >2000 h of continuous operation in the reactor environment. Mechanical problems have been solved with these transducers to the point where the electrical coils are now the limiting factor on lifetime. This paper presents the results of the development of the drag disk and turbine with problems and solutions pointed out

  7. Probabilistic Sensitivities for Fatigue Analysis of Turbine Engine Disks

    OpenAIRE

    Harry R. Millwater; R. Wesley Osborn

    2006-01-01

    A methodology is developed and applied that determines the sensitivities of the probability-of-fracture of a gas turbine disk fatigue analysis with respect to the parameters of the probability distributions describing the random variables. The disk material is subject to initial anomalies, in either low- or high-frequency quantities, such that commonly used materials (titanium, nickel, powder nickel) and common damage mechanisms (inherent defects or su...

  8. Automation of ultrasonic testing of turbine disk billets

    International Nuclear Information System (INIS)

    Gorodkov, V.E.; Domashevskij, B.N.; Pron', N.I.; Tkachenko, V.A.

    1984-01-01

    cations of ultrasonic facility for automation of testing turbine disk billets of 25Kh2PMFA and 34KhM1A steels are considered. The operating principle and the design of ''Disk-1'' facility are described, its test results are presented. It is shown that the facility increases the test efficiency five times, enables to estimate dimensions of revealed defect with regard to the quality of acoustic contact, thus facilitating the work of personnel and improving the test quality

  9. Probabilistic Sensitivities for Fatigue Analysis of Turbine Engine Disks

    Directory of Open Access Journals (Sweden)

    Harry R. Millwater

    2006-01-01

    Full Text Available A methodology is developed and applied that determines the sensitivities of the probability-of-fracture of a gas turbine disk fatigue analysis with respect to the parameters of the probability distributions describing the random variables. The disk material is subject to initial anomalies, in either low- or high-frequency quantities, such that commonly used materials (titanium, nickel, powder nickel and common damage mechanisms (inherent defects or surface damage can be considered. The derivation is developed for Monte Carlo sampling such that the existing failure samples are used and the sensitivities are obtained with minimal additional computational time. Variance estimates and confidence bounds of the sensitivity estimates are developed. The methodology is demonstrated and verified using a multizone probabilistic fatigue analysis of a gas turbine compressor disk analysis considering stress scatter, crack growth propagation scatter, and initial crack size as random variables.

  10. Comparison of central axis and jet ring coolant supply for turbine disk cooling on a SSME-HPOTP model

    Science.gov (United States)

    Kim, Y. W.; Metzger, D. E.

    1992-01-01

    The test facility, test methods and results are presented for an experimental study modeling the cooling of turbine disks in the blade attachment regions with multiple impinging jets, in a configuration simulating the disk cooling method employed on the Space Shuttle Main Engine oxygen turbopump. The study's objective was to provide a comparison of detailed local convection heat transfer rates obtained for a single center-supply of disk coolant with those obtained with the present flight configuration where disk coolant is supplied through an array of 19 jets located near the disk outer radius. Specially constructed disk models were used in a program designed to evaluate possible benefits and identify any possible detrimental effects involved in employing an alternate disk cooling scheme. The study involved the design, construction and testing of two full scale rotating model disks, one plane and smooth for baseline testing and the second contoured to the present flight configuration, together with the corresponding plane and contoured stator disks. Local heat transfer rates are determined from the color display of encapsulated liquid crystals coated on the disk in conjunction with use of a computer vision system. The test program was composed of a wide variety of disk speeds, flowrates, and geometrical configurations, including testing for the effects of disk boltheads and gas ingestion from the gas path region radially outboard of the disk-cavity.

  11. Powder metallurgy processing of high strength turbine disk alloys

    Science.gov (United States)

    Evans, D. J.

    1976-01-01

    Using vacuum-atomized AF2-1DA and Mar-M432 powders, full-scale gas turbine engine disks were fabricated by hot isostatically pressing (HIP) billets which were then isothermally forged using the Pratt & Whitney Aircraft GATORIZING forging process. While a sound forging was produced in the AF2-1DA, a container leak had occurred in the Mar-M432 billet during HIP. This resulted in billet cracking during forging. In-process control procedures were developed to identify such leaks. The AF2-1DA forging was heat treated and metallographic and mechanical property evaluation was performed. Mechanical properties exceeded those of Astroloy, one of the highest temperature capability turbine disk alloys presently used.

  12. Wet-steam erosion of steam turbine disks and shafts

    International Nuclear Information System (INIS)

    Averkina, N. V.; Zheleznyak, I. V.; Kachuriner, Yu. Ya.; Nosovitskii, I. A.; Orlik, V. G.; Shishkin, V. I.

    2011-01-01

    A study of wet-steam erosion of the disks and the rotor bosses or housings of turbines in thermal and nuclear power plants shows that the rate of wear does not depend on the diagrammed degree of moisture, but is determined by moisture condensing on the surfaces of the diaphragms and steam inlet components. Renovating the diaphragm seals as an assembly with condensate removal provides a manifold reduction in the erosion.

  13. Determination of elastic stresses in gas-turbine disks

    Science.gov (United States)

    Manson, S S

    1947-01-01

    A method is presented for the calculation of elastic stresses in symmetrical disks typical of those of a high-temperature gas turbine. The method is essentially a finite-difference solution of the equilibrium and compatibility equations for elastic stresses in a symmetrical disk. Account can be taken of point-to-point variations in disk thickness, in temperature, in elastic modulus, in coefficient of thermal expansion, in material density, and in Poisson's ratio. No numerical integration or trial-and-error procedures are involved and the computations can be performed in rapid and routine fashion by nontechnical computers with little engineering supervision. Checks on problems for which exact mathematical solutions are known indicate that the method yields results of high accuracy. Illustrative examples are presented to show the manner of treating solid disks, disks with central holes, and disks constructed either of a single material or two or more welded materials. The effect of shrink fitting is taken into account by a very simple device.

  14. Fabrication of Turbine Disk Materials by Additive Manufacturing

    Science.gov (United States)

    Sudbrack, Chantal; Bean, Quincy A.; Cooper, Ken; Carter, Robert; Semiatin, S. Lee; Gabb, Tim

    2014-01-01

    Precipitation-strengthened, nickel-based superalloys are widely used in the aerospace and energy industries due to their excellent environmental resistance and outstanding mechanical properties under extreme conditions. Powder-bed additive manufacturing (AM) technologies offer the potential to revolutionize the processing of superalloy turbine components by eliminating the need for extensive inventory or expensive legacy tooling. Like selective laser melting (SLM), electron beam melting (EBM) constructs three-dimensional dense components layer-by-layer by melting and solidification of atomized, pre-alloyed powder feedstock within 50-200 micron layers. While SLM has been more widely used for AM of nickel alloys like 718, EBM offers several distinct advantages, such as less retained residual stress, lower risk of contamination, and faster build rates with multiple-electron-beam configurations. These advantages are particularly attractive for turbine disks, for which excessive residual stress and contamination can shorten disk life during high-temperature operation. In this presentation, we will discuss the feasibility of fabricating disk superalloy components using EBM AM. Originally developed using powder metallurgy forging processing, disk superalloys contain a higher refractory content and precipitate volume fraction than alloy 718, thus making them more prone to thermal cracking during AM. This and other challenges to produce homogeneous builds with desired properties will be presented. In particular, the quality of lab-scale samples fabricated via a design of experiments, in which the beam current, build temperature, and beam velocity were varied, will be summarized. The relationship between processing parameters, microstructure, grain orientation, and mechanical response will be discussed.

  15. Simulation and measurement of ferromagnetic impurities in non-magnetic aeroengine turbine disks using fluxgate magnetometers

    OpenAIRE

    Sebastian Hantscher; Ruixin Zhou; Albert Seidl; Johann Hinken; Christian Ziep

    2015-01-01

    In this paper, ferromagnetic impurities in paramagnetic aeroengine turbine disks are investigated. Because such inclusions represent a significant threat in aviation, a detailed analysis is required for impured turbine disks. For this purpose, sensitive fluxgate magnetometers are used. After a premagnetisation, this sensor is able to detect small ferromagnetic particles by recording the variation of the magnetic flux density while the disk rotates below the sensor head. This trajectory create...

  16. Ultrasonic inspection method and system for detection of steeple cracking in turbine disk rims

    International Nuclear Information System (INIS)

    Birring, A.S.; Lamping, G.A.; Van der Veer, W.R.; Hanley, J.J.

    1990-01-01

    Steam turbine disks which operate under high cyclic stress in a moist environment can develop cracks in the disk-rim steeples. Detection of these cracks using nondestructive testing methods is necessary to assure safe operation and avoid unnecessary disk replacement. Both magnetic particle (MT) and ultrasonic testing (UT) can be used to inspect the steeples; however, UT can be used without removing the blades. A system for inspecting bladed steeples has been developed that can be applied on a range of disks including those in Westinghouse, General Electric, and Allis Chalmers turbines. The system performs an inspection as the turbine is rotated at slow speeds over turning rolls. This procedure greatly reduces inspection time because the inspection can be done without deblading the disk or resetting the inspection equipment for different rim segments

  17. A plastic stress intensity factor approach to turbine disk structural integrity assessment

    OpenAIRE

    Shlyannikov, V.; Zakharov, A.; Yarullin, R.

    2016-01-01

    This study based on a new fracture mechanics parameter is concerned with assessing the integrity of cracked steam turbine disk which operate under startup-shutdown cyclic loading conditions. Damage accumulation and growth in service have occurred on the inner surface of slot fillet of key. In order to determine elastic-plastic fracture mechanics parameters full-size stress-strain state analysis of turbine disk was performed for a quote-elliptical part-through cracks under consider...

  18. A plastic stress intensity factor approach to turbine disk structural integrity assessment

    Directory of Open Access Journals (Sweden)

    V. Shlyannikov

    2016-07-01

    Full Text Available This study based on a new fracture mechanics parameter is concerned with assessing the integrity of cracked steam turbine disk which operate under startup-shutdown cyclic loading conditions. Damage accumulation and growth in service have occurred on the inner surface of slot fillet of key. In order to determine elastic-plastic fracture mechanics parameters full-size stress-strain state analysis of turbine disk was performed for a quote-elliptical part-through cracks under considering loading conditions. As a result distributions of elastic and plastic stress intensity factors along crack front in slot fillet of key of turbine disk depending on surface crack form are defined. An engineering approach to the prediction of carrying capacity of cracked turbine disk which is sensitive to the loading history at maintenance is proposed. The predictions of the rate of crack growth and residual lifetime of steam turbine disk are compared for elastic and elastic-plastic solutions. It is shown that the previously proposed elastic crack growth models provide overestimate the lifetime with respect to the present one. An advantage to use the plastic stress intensity factor to characterize the fracture resistance as the self-dependent unified parameter for a variety of turbine disk configurations rather than the magnitude of the elastic stress intensity factors alone is discussed.

  19. A RESOLVED NEAR-INFRARED IMAGE OF THE INNER CAVITY IN THE GM Aur TRANSITIONAL DISK

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Daehyeon; Yang, Yi [Department of Astronomical Science, SOKENDAI (The Graduate University for Advanced Studies), 2-21-1 Osawa, Mitaka, Tokyo, 181-8588 (Japan); Hashimoto, Jun; Kusakabe, Nobuhiko [Astrobiology Center of NINS 2-21-1, Osawa, Mitaka, Tokyo, 181-8588 (Japan); Carson, Joseph C. [Department of Physics and Astronomy, College of Charleston 66 George Street, Charleston, SC 29424 (United States); Janson, Markus [Department of Astronomy, Stockholm University, AlbaNova University Center SE-106 91 Stockholm (Sweden); Kwon, Jungmi; Nakagawa, Takao [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210 (Japan); Mayama, Satoshi [The Center for the Promotion of Integrated Sciences, SOKENDAI (The Graduate University for Advanced Studies), Shonan International Village, Hayama-cho, Miura-gun, Kanagawa 240-0193 (Japan); Uyama, Taichi [Department of Astronomy, The University of Tokyo 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-0033 (Japan); Kudo, Tomoyuki; Currie, Thayne [Subaru Telescope, National Astronomical Observatory of Japan 650 North A’ohoku Place, Hilo, HI 96720 (United States); Abe, Lyu [Laboratoire Lagrange (UMR 7293), Universite de Nice-Sophia Antipolis, CNRS, Observatoire de la Coted’azur 28 avenue Valrose, F-06108 Nice Cedex 2 (France); Akiyama, Eiji [National Astronomical Observatory of Japan 2-21-1, Osawa, Mitaka, Tokyo, 181-8588 (Japan); Brandner, Wolfgang [Max Planck Institute for Astronomy, Köonigstuhl 17, D-69117 Heidelberg (Germany); Brandt, Timothy D.; Feldt, Markus [Astrophysics Department, Institute for Advanced Study Princeton, NJ (United States); Goto, Miwa [Universitats-Sternwarte Munchen, Ludwig-Maximilians-Universitat, Scheinerstr. 1, D-81679 Munchen (Germany); Grady, Carol A. [Exoplanets and Stellar Astrophysics Laboratory, Code 667, Goddard Space Flight Center Greenbelt, MD 20771 (United States); and others

    2016-11-01

    We present high-contrast H -band polarized intensity (PI) images of the transitional disk around the young solar-like star GM Aur. The near-infrared direct imaging of the disk was derived by polarimetric differential imaging using the Subaru 8.2 m Telescope and HiCIAO. An angular resolution and an inner working angle of 0.″07 and r ∼ 0.″05, respectively, were obtained. We clearly resolved a large inner cavity, with a measured radius of 18 ± 2 au, which is smaller than that of a submillimeter interferometric image (28 au). This discrepancy in the cavity radii at near-infrared and submillimeter wavelengths may be caused by a 3–4 M {sub Jup} planet about 20 au away from the star, near the edge of the cavity. The presence of a near-infrared inner cavity is a strong constraint on hypotheses for inner cavity formation in a transitional disk. A dust filtration mechanism has been proposed to explain the large cavity in the submillimeter image, but our results suggest that this mechanism must be combined with an additional process. We found that the PI slope of the outer disk is significantly different from the intensity slope obtained from HST /NICMOS, and this difference may indicate the grain growth process in the disk.

  20. Millimetre spectral indices of transition disks and their relation to the cavity radius

    Science.gov (United States)

    Pinilla, P.; Benisty, M.; Birnstiel, T.; Ricci, L.; Isella, A.; Natta, A.; Dullemond, C. P.; Quiroga-Nuñez, L. H.; Henning, T.; Testi, L.

    2014-04-01

    Context. Transition disks are protoplanetary disks with inner depleted dust cavities that are excellent candidates for investigating the dust evolution when there is a pressure bump. A pressure bump at the outer edge of the cavity allows dust grains from the outer regions to stop their rapid inward migration towards the star and to efficiently grow to millimetre sizes. Dynamical interactions with planet(s) have been one of the most exciting theories to explain the clearing of the inner disk. Aims: We look for evidence of millimetre dust particles in transition disks by measuring their spectral index αmm with new and available photometric data. We investigate the influence of the size of the dust depleted cavity on the disk integrated millimetre spectral index. Methods: We present the 3-mm (100 GHz) photometric observations carried out with the Plateau de Bure Interferometer of four transition disks: LkHα 330, UX Tau A, LRLL 31, and LRLL 67. We used the available values of their fluxes at 345 GHz to calculate their spectral index, as well as the spectral index for a sample of twenty transition disks. We compared the observations with two kinds of models. In the first set of models, we considered coagulation and fragmentation of dust in a disk in which a cavity is formed by a massive planet located at different positions. The second set of models assumes disks with truncated inner parts at different radii and with power-law dust-size distributions, where the maximum size of grains is calculated considering turbulence as the source of destructive collisions. Results: We show that the integrated spectral index is higher for transition disks (TD) than for regular protoplanetary disks (PD) with mean values of bar{αmmTD} = 2.70 ± 0.13 and bar{αmmPD} = 2.20 ± 0.07 respectively. For transition disks, the probability that the measured spectral index is positively correlated with the cavity radius is 95%. High angular resolution imaging of transition disks is needed to

  1. Dynamic behaviour of pump-turbine runner: From disk to prototype runner

    International Nuclear Information System (INIS)

    Huang, X X; Egusquiza, E; Valero, C; Presas, A

    2013-01-01

    In recent decades, in order to increase output power of hydroelectric turbomachinery, the design head and the flow rate of the hydraulic turbines have been increased greatly. This has led to serious vibratory problems. The pump-turbines have to work at various operation conditions to satisfy the requirements of the power grid. However, larger hydraulic forces will result in high vibration levels on the turbines, especially, when the machines operate at off-design conditions. Due to the economic considerations, the pump-turbines are built as light as possible, which will change the dynamic response of the structures. According to industrial cases, the fatigue damage of the pump-turbine runner induced by hydraulic dynamic forces usually happens on the outer edge of the crown, which is near the leading edges of blades. To better understand the reasons for this kind of fatigue, it is extremely important to investigate the dynamic response behaviour of the hydraulic turbine, especially the runner, by experimental measurement and numerical simulation. The pump-turbine runner has a similar dynamic response behaviour of the circular disk. Therefore, in this paper the dynamic response analyses for circular disks with different dimensions and disk-blades-disk structures were carried out to better understand the fundamental dynamic behaviour for the complex turbomachinery. The influences of the pattern and number of blades were discussed in detail

  2. Underwater sound transmission through arrays of disk cavities in a soft elastic medium.

    Science.gov (United States)

    Calvo, David C; Thangawng, Abel L; Layman, Christopher N; Casalini, Riccardo; Othman, Shadi F

    2015-10-01

    Scattering from a cavity in a soft elastic medium, such as silicone rubber, resembles scattering from an underwater bubble in that low-frequency monopole resonance is obtainable in both cases. Arrays of cavities can therefore be used to reduce underwater sound transmission using thin layers and low void fractions. This article examines the role of cavity shape by microfabricating arrays of disk-shaped air cavities into single and multiple layers of polydimethylsiloxane. Comparison is made with the case of equivalent volume cylinders which approximate spheres. Measurements of ultrasonic underwater sound transmission are compared with finite element modeling predictions. The disks provide a deeper transmission minimum at a lower frequency owing to the drum-type breathing resonance. The resonance of a single disk cavity in an unbounded medium is also calculated and compared with a derived estimate of the natural frequency of the drum mode. Variation of transmission is determined as a function of disk tilt angle, lattice constant, and layer thickness. A modeled transmission loss of 18 dB can be obtained at a wavelength about 20 times the three-layer thickness, and thinner results (wavelength/thickness ∼ 240) are possible for the same loss with a single layer depending on allowable hydrostatic pressure.

  3. Preliminary Test of Friction disk type turbine for S-CO{sub 2} cycle application

    Energy Technology Data Exchange (ETDEWEB)

    Baik, Seungjoon; Kim, Hyeon Tae; Lee, Jeong Ik [KAIST, Daejeon (Korea, Republic of)

    2016-05-15

    Due to the relatively mild sodium-CO{sub 2} interaction, the S-CO{sub 2} Brayton cycle can reduce the accident consequence compared to the steam Rankine cycle. Also the S-CO{sub 2} power conversion cycle can achieve high efficiency for SFR core thermal condition. Moreover, the S-CO{sub 2} power cycle can reduce the total cycle footprint due to high density of the working fluid. However, the high pressure operating condition and low viscosity of the fluid cause difficulties in designing appropriate seals and multi-stage turbo machineries. To solve the problem for designing turbo machineries in a creative way, KAIST research team tested a friction disk type turbine concept for the S-CO{sub 2} cycle application. In this paper, the investigation of the Tesla turbine and preliminary test results with compressed air are covered. The KAIST research team investigated a friction disk type turbine, named as Tesla turbine, for the S-CO{sub 2} power cycle applications. Due to the robust design of the fiction disk type, the Tesla turbine technology can be utilized not only for S-CO{sub 2} turbo machinery but also for the multi-phase or sludge flow turbo machinery. The preliminary test of lab-scale Tesla turbine with compressed air was conducted. The high pressure vessel was manufactured for the S-CO{sub 2} operating condition. The test will be concentrated on the turbine efficiency measurement under various conditions and development of the design methodology.

  4. Split-disk micro-lasers: Tunable whispering gallery mode cavities

    Directory of Open Access Journals (Sweden)

    T. Siegle

    2017-09-01

    Full Text Available Optical micro-cavities of various types have emerged as promising photonic structures, for both the investigation of fundamental science in cavity quantum electrodynamics and simultaneously for various applications, e.g., lasers, filters, or modulators. In either branch a demand for adjustable and tunable photonic devices becomes apparent, which has been mainly based on the modification of the refractive index of the micro-resonators so far. In this paper, we report on a novel type of whispering gallery mode resonator where resonance tuning is achieved by modification of the configuration. This is realized by polymeric split-disks consisting of opposing half-disks with an intermediate air gap. Functionality of the split-disk concept and its figures of merit like low-threshold lasing are demonstrated for laser dye-doped split-disks fabricated by electron beam lithography on Si substrates. Reversible resonance tuning is achieved for split-disks structured onto elastomeric substrates by direct laser writing. The gap width and hence the resonance wavelength can be well-controlled by mechanically stretching the elastomer and exploiting the lateral shrinkage of the substrate. We demonstrate a broad spectral tunability of laser modes by more than three times the free spectral range. These cavities have the potential to form a key element of flexible and tunable photonic circuits based on polymers.

  5. Determination of stresses in gas-turbine disks subjected to plastic flow and creep

    Science.gov (United States)

    Millenson, M B; Manson, S S

    1948-01-01

    A finite-difference method previously presented for computing elastic stresses in rotating disks is extended to include the computation of the disk stresses when plastic flow and creep are considered. A finite-difference method is employed to eliminate numerical integration and to permit nontechnical personnel to make the calculations with a minimum of engineering supervision. Illustrative examples are included to facilitate explanation of the procedure by carrying out the computations on a typical gas-turbine disk through a complete running cycle. The results of the numerical examples presented indicate that plastic flow markedly alters the elastic-stress distribution.

  6. A rare nasal cavity mass in a child: Accessory middle turbinate

    Directory of Open Access Journals (Sweden)

    Andrew Chang

    2016-09-01

    Full Text Available Objectives: The accessory middle turbinate, a rare anatomical variation of the nasal cavity, have been systematically studied in adults. Presence of accessory middle turbinate and its clinical significance in a child has not been reported. We describe clinical appearance and radiologic features of accessory middle turbinate in a child. Methods: Retrospective chart review. Results: A 3-year-old boy presented to the otolaryngology clinic for evaluation of recurrent epistaxis. Anterior rhinoscopy revealed moist nasal mucosa without inflammation and bilateral prominent blood vessels on the anterior nasal septum. Nasal endoscopy showed turbinate like protuberances in bilateral middle meatus. CT images documented accessory middle turbinate in the bilateral nasal cavity. Conclusion: Otolaryngologists should be cognizant of anatomical variations of middle turbinate to achieve correct diagnosis and avoid potential complications during surgical management.

  7. A rare nasal cavity mass in a child: Accessory middle turbinate

    OpenAIRE

    Chang, Andrew; Ulualp, Seckin O; Koral, Korgun; Veling, Maria

    2016-01-01

    Objectives: The accessory middle turbinate, a rare anatomical variation of the nasal cavity, have been systematically studied in adults. Presence of accessory middle turbinate and its clinical significance in a child has not been reported. We describe clinical appearance and radiologic features of accessory middle turbinate in a child. Methods: Retrospective chart review. Results: A 3-year-old boy presented to the otolaryngology clinic for evaluation of recurrent epistaxis. Anterior rhinoscop...

  8. High temperature initiation and propagation of cracks in 12%Cr-steel turbine disks

    Directory of Open Access Journals (Sweden)

    S. Foletti

    2013-10-01

    Full Text Available This work aims to study the crack propagation in 12%Cr steel for turbine disks. Creep Crack Growth (CCG tests on CT specimens have been performed to define the proper fracture mechanics which describes the initiation of the crack propagation and the crack growth behaviour for the material at high temperature. Results have been used to study the occurrence of crack initiation on a turbine disk at the extreme working temperature and stress level experienced during service, and validate the use of C* integral in correlating creep growth rate on the disk component, in case C* is numerically calculated through FEM analysis or calculated by the use of reference stress concept.

  9. Deep drawing experiences of niobium disk for PEFP SRF cavity prototype

    International Nuclear Information System (INIS)

    Kim, Han Sung; An, Sun; Zhang, Liping; Tang, Yazhe; Li, Ying Min; Kwon, Hyeok Jung; Cho, Yong Sub

    2009-01-01

    A superconducting radio frequency (SRF) cavity with a geometrical beta of 0.42 has been designed to accelerate a proton beam after 100 MeV for an extension of Proton Engineering Frontier Project (PEFP). The designed cavity shape is an elliptical and the resonant frequency is 700 MHz. In order to confirm the RF and mechanical properties of the cavity, two prototypes of copper cavities have been fabricated and tested. Based on the experiences gained with the copper prototypes, two niobium prototypes have been designed. One is two-cell cavity and the other is five cell cavity. The two-cell cavity is for finalizing the niobium cavity production procedure and testing the cavity RF properties at a low temperature and moderate power level. The five-cell cavity is for checking the production quality and testing vertical test system in the future. Both of them are under fabrication. Through the fabrication of the niobium prototype, several issues such as deep drawing, electron beam welding and surface treatment will be addressed. The drawing of the PEPF SRF low beta cavity is shown in Fig. 1. Major parameters for the cavity are like following. - Frequency: 700 MHz - Operating mode: TM010 pi mode - Cavity type: Elliptical - Geometrical beta: 0.42 - Number of cells: 5 per cavity - Accelerating gradient: 8 MV/m - Epeak/Eacc: 3.71 - Bpeak/Eacc: 7.47 mT/(MV/m) - R/Q: 102.3 ohm - Epeak: 29.68 MV/m - Field flatness: 1.56 % - Cell to cell coupling: 1.41 % - Geometrical factor: 121.68 ohm - Cavity wall thickness: 4.3 mm - Lorentz force detuning: 0.4 Hz/(MV/m)2 - Stiffening structure: Double ring - Effective length: 0.45 m - External Q of FPC: 8.0E5 ±20 % - HOM load: less than 2 W - HOM Qext requirement: less than 3.0E5 At present, all the niobium disk and plates for cavity and NbTi flanges for beam pipe flange are prepared

  10. CFD and Experimental Studies on Wind Turbines in Complex Terrain by Improved Actuator Disk Method

    Science.gov (United States)

    Liu, Xin; Yan, Shu; Mu, Yanfei; Chen, Xinming; Shi, Shaoping

    2017-05-01

    In this paper, an onshore wind farm in mountainous area of southwest China was investigated through numerical and experimental methods. An improved actuator disk method, taking rotor data (i.e. blade geometry information, attack angle, blade pitch angle) into account, was carried out to investigate the flow characteristic of the wind farm, especially the wake developing behind the wind turbines. Comparing to the classic AD method and the situ measurements, the improved AD shows better agreements with the measurements. The turbine power was automatically predicted in CFD by blade element method, which agreed well with the measurement results. The study proved that the steady CFD simulation with improved actuator disk method was able to evaluate wind resource well and give good balance between computing efficiency and accuracy, in contrary to much more expensive computation methods such as actuator-line/actuator-surface transient model, or less accurate methods such as linear velocity reduction wake model.

  11. Disk

    NARCIS (Netherlands)

    P.A. Boncz (Peter); L. Liu (Lei); M. Tamer Özsu

    2008-01-01

    htmlabstractIn disk storage, data is recorded on planar, round and rotating surfaces (disks, discs, or platters). A disk drive is a peripheral device of a computer system, connected by some communication medium to a disk controller. The disk controller is a chip, typically connected to the CPU of

  12. Corrosion fatigue of bladed disk attachments of low-pressure turbine

    International Nuclear Information System (INIS)

    Asai, K.; Sakurai, S.; Nomura, K.; Saito, E.; Namura, K.

    2004-01-01

    The mechanism of a disk cracking in a low-pressure steam turbine was investigated by finite-element and fracture mechanics analysis and, based on the results of the investigation, a life assessment method was derived. The disk cracking was found to be caused by growth of corrosion pits, superposition of multiple vibration modes, and an increase in the standard deviation of the natural frequency of grouped blades after long-term operation. Taking these findings into consideration, the authors then developed a life-assessment method for disk cracking composed of evaluations (1) maximum corrosion pit size at the current situation, (2) corrosion pit growth after a certain term, and (3) failure-occurrence ratio for the estimated corrosion pit depth. Maximum corrosion-pit size is evaluated by extreme value statistical analysis using the data obtained by replica inspection. The failure-occurrence ratio is evaluated by Monte Carlo simulation considering two uncertainties, namely, the standard deviation of the natural frequency of grouped blades and the stimulus ratio. The values of both uncertainties were determined by the inverse problem analysis of the disk cracking. In light of these results, the authors found that replacing conventional tenon-shroud grouped blades with continuous-cover blades is effective from the view point of vibratory behavior. (orig.)

  13. Identification of Yeast Species In the Oral Cavity of Iranian Soldiers By Disk Diffusion Method

    Directory of Open Access Journals (Sweden)

    M. Imami

    2008-02-01

    Full Text Available Background:The disk diffusion method for identification of yeasts species was performed based on different but distinct susceptibilities of yeasts spp.to chemicals:janus green, ethidium bromide,2,3,5-triphenyltetrazolium chloride, brilliant green, cycloheximide and rhodamine 6G. Methods: Atotal of 568 Iranian soldiers went under study for isolation and identification of Yeast species from their oral cavity. Asterile swab was used for each individual and specimens were collected from the nasopharynx region, then inoculated to petri dishes containing Sabouraud Dextrose Agar and incubated for 48 hrs at 37 °C. All colonies were counted and stocked in distilled water and stored in a refrigerator for further analysis. The yeasts were identified by the “disk diffusion test” [6,8]. This is a simple, rapid, accurate, and inexpensive technique presented by Sobczak [8]. By this method we identified yeast species within 24-48 hrs. Results: 51.4% of petri dishes were positive for yeast species and 318 strains were identified. Candida albicans, Candida kefyr, Candida tropicalis and Candida guilliermondii were the most common yeast species isolated from the oral cavity of soldiers. Conclusion: We used this method because of its simplicity and other beneficial characteristics for rapid identification of large and numerous isolates and the results were compared with other morphological characters such as chlamydospore and germ tube production. In addition,we used some type strains (Candida parapsilosis: PTCC 5089,Candida tropicalis: PTCC 5028,Saccharomyces cerevisiae:PTCC 5052,Candida lipolytica: PTCC 5063,Candida lipolytica:PTCC 5064,and the results were acceptable.

  14. Characterization of Deficiencies in the Frequency Domain Forced Response Analysis Technique for Turbine Bladed Disks

    Science.gov (United States)

    Brown, Andrew M.; Schmauch, Preston

    2012-01-01

    Turbine blades in rocket and jet engine turbomachinery experience enormous harmonic loading conditions. These loads result from the integer number of upstream and downstream stator vanes as well as the other turbine stages. The standard technique for forced response analysis to assess structural integrity is to decompose a CFD generated flow field into its harmonic components, and to then perform a frequency response analysis at the problematic natural frequencies. Recent CFD analysis and water-flow testing at NASA/MSFC, though, indicates that this technique may miss substantial harmonic and non-harmonic excitation sources that become present in complex flows. These complications suggest the question of whether frequency domain analysis is capable of capturing the excitation content sufficiently. Two studies comparing frequency response analysis with transient response analysis, therefore, have been performed. The first is of a bladed disk with each blade modeled by simple beam elements. It was hypothesized that the randomness and other variation from the standard harmonic excitation would reduce the blade structural response, but the results showed little reduction. The second study was of a realistic model of a bladed-disk excited by the same CFD used in the J2X engine program. The results showed that the transient analysis results were up to 10% higher for "clean" nodal diameter excitations and six times larger for "messy" excitations, where substantial Fourier content around the main harmonic exists.

  15. The k-ε-fP model applied to double wind turbine wakes using different actuator disk force methods

    DEFF Research Database (Denmark)

    Laan, van der, Paul Maarten; Sørensen, Niels N.; Réthoré, Pierre-Elouan

    2015-01-01

    The newly developed k-ε-fP  eddy viscosity model is applied to double wind turbine wake configurations in a neutral atmospheric boundary layer, using a Reynolds-Averaged Navier–Stokes solver. The wind turbines are represented by actuator disks. A proposed variable actuator disk force method...... two methods overpredict it. The results of the k-ε-fP  eddy viscosity model are also compared with the original k-ε eddy viscosity model and large-eddy simulations. Compared to the large-eddy simulations-predicted velocity and power deficits, the k-ε-fP  is superior to the original k-ε model...

  16. The deterministic prediction of failure of low pressure steam turbine disks

    International Nuclear Information System (INIS)

    Liu, Chun; Macdonald, D.D.

    1993-01-01

    Localized corrosion phenomena, including pitting corrosion, stress corrosion cracking, and corrosion fatigue, are the principal causes of corrosion-induced damage in electric power generating facilities and typically result in more than 50% of the unscheduled outages. Prediction of damage, so that repairs and inspections can be made during scheduled outages, could have an enormous impact on the economics of electric power generation. To date, prediction of corrosion damage has been made on the basis of empirical/statistical methods that have proven to be insufficiently robust and accurate to form the basis for the desired inspection/repair protocol. In this paper, we describe a deterministic method for predicting localized corrosion damage. We have used the method to illustrate how pitting corrosion initiates stress corrosion cracking (SCC) for low pressure steam turbine disks downstream of the Wilson line, where a thin condensed liquid layer exists on the steel disk surfaces. Our calculations show that the SCC initiation and propagation are sensitive to the oxygen content of the steam, the environment in the thin liquid condensed layer, and the stresses that the disk experiences in service

  17. Two interacting hard disks within a circular cavity: towards a quasi-equilibrium quantal equation of states

    International Nuclear Information System (INIS)

    Nakazono, Naofumi; Kato, Takeo; Nakamura, Katsuhiro

    2005-01-01

    Two interacting hard disks confined in a circular cavity are investigated. Each disk shows a free motion except when bouncing elastically with its partner and with the boundary wall. According to the analysis of Lyapunov exponents, this system is classically nonintegrable and almost chaotic because of the (short-range) interaction between the disks. The system can be quantized by incorporating the excluded volume effect for the wave function. Eigenvalues and eigenfunctions are obtained by tuning the relative size between the disks and the billiard. The pressure P is defined as the derivative of each eigenvalue with respect to the cavity volume V. Since the energy spectra of eigenvalues versus the disk size show a multitude of level repulsions, P-V characteristics shows the anomalous pressure fluctuations accompanied by many van der Waals-like peaks in each of excited eigenstates taken as a quasi-equilibrium. For each eigenstate, we calculate the expectation values of the square distance between two disks, and point out their relationship with the pressure fluctuations. Role of Bose and Fermi statistics is also investigated

  18. Co-generation on steam industrial systems with disks turbines; Co-geracao em sistemas industriais de vapor com turbinas de discos

    Energy Technology Data Exchange (ETDEWEB)

    Lezsovits, Ferenc [Universidad de Tecnologia y Economia de Budapest (Hungary)

    2010-03-15

    The disk turbine, also called Tesla turbine, being of simple construction and low cost, can be used as steam pressure reduction on industrial systems, generating simultaneously electric power, becoming the co-generation even at lower levels. Can be used for various operational parameters and mass flux ratios.This paper analyses the advantages and disadvantages of the turbines under various operation conditions.

  19. Characterization of Deficiencies in the Frequency Domain Forced Response Analysis Technique for Supersonic Turbine Bladed Disks

    Science.gov (United States)

    Brown, Andrew M.; Schmauch, Preston

    2011-01-01

    Turbine blades in rocket and jet engine turbomachinery experience enormous harmonic loading conditions. These loads result from the integer number of upstream and downstream stator vanes as well as the other turbine stages. Assessing the blade structural integrity is a complex task requiring an initial characterization of whether resonance is possible and then performing a forced response analysis if that condition is met. The standard technique for forced response analysis in rocket engines is to decompose a CFD-generated flow field into its harmonic components, and to then perform a frequency response analysis at the problematic natural frequencies. Recent CFD analysis and water-flow testing at NASA/MSFC, though, indicates that this technique may miss substantial harmonic and non-harmonic excitation sources that become present in complex flows. A substantial effort has been made to account for this denser spatial Fourier content in frequency response analysis (described in another paper by the author), but the question still remains whether the frequency response analysis itself is capable of capturing the excitation content sufficiently. Two studies comparing frequency response analysis with transient response analysis, therefore, of bladed-disks undergoing this complex flow environment have been performed. The first is of a bladed disk with each blade modeled by simple beam elements. Six loading cases were generated by varying a baseline harmonic excitation in different ways based upon cold-flow testing from Heritage Fuel Air Turbine Test. It was hypothesized that the randomness and other variation from the standard harmonic excitation would reduce the blade structural response, but the results showed little reduction. The second study was of a realistic model of a bladed-disk excited by the same CFD used in the J2X engine program. It was hypothesized that enforcing periodicity in the CFD (inherent in the frequency response technique) would overestimate the

  20. Investigation of Fano resonances induced by higher order plasmon modes on a circular nano-disk with an elongated cavity

    KAUST Repository

    Amin, Muhammad Ruhul

    2012-08-10

    In this paper, a planar metallic nanostructure design, which supports two distinct Fano resonances in its extinction cross-section spectrum under normally incident and linearly polarized electromagnetic field, is proposed. The proposed design involves a circular disk embedding an elongated cavity; shifting and rotating the cavity break the symmetry of the structure with respect to the incident field and induce higher order plasmon modes. As a result, Fano resonances are generated in the visible spectrum due to the destructive interference between the sub-radiant higher order modes and super-radiant the dipolar mode. The Fano resonances can be tuned by varying the cavity\\'s width and the rotation angle. An RLC circuit, which is mathematically equivalent to a mass-spring oscillator, is proposed to model the optical response of the nanostructure design.

  1. Development of advanced P/M Ni-base superalloys for turbine disks

    Directory of Open Access Journals (Sweden)

    Garibov Genrikh S.

    2014-01-01

    Full Text Available In the process of evolution of powder metallurgy in Russia the task permanently formulated was the following: to improve strength properties of P/M superalloys without application of additional complex HIPed blanks deformation operation. On the other hand development of a turbine disk material structure to ensure an improvement in aircraft engine performance requires the use of special HIP and heat treatment conditions. To ensure maximum strength properties of disk materials it is necessary to form a structure which would have optimum size of solid solution grains, γ′-phases and carbides. Along with that heating of the material up to a temperature determined by solvus of an alloy ensures a stable and reproducible level of mechanical properties of the disks. The above-said can be illustrated by successful mastering of new complex-alloyed VVP-class superalloys with the use of powder size − 100 μm. Application of special HIP and heat treatment conditions for these superalloys to obtain the desired grain size and the strengthening γ′-phase precipitates allowed a noticeable improvement in ultimate tensile strength and yield strength up to ≥1600 MPa and ≥1200 MPa respectively. 100 hrs rupture strength at 650 ∘C and 750 ∘C was improved up to 1140 MPa and 750 MPa respectively. P/M VVP nickel-base superalloys offer higher characteristics in comparison with many superalloys designed for the same purposes. HIPed disc compacts manufactured from PREP-powder have a homogeneous micro- and macrostructure, a stable level of mechanical properties.

  2. Polarimetric Imaging of Large Cavity Structures in the Pre-transitional Protoplanetary Disk Around PDS 70: Observations of the Disk

    Science.gov (United States)

    Hashimoto, J.; Dong, R.; Kudo, T.; Honda, M.; McClure, M. K.; Zhu, Z.; Muto, T.; Wisniewski, J.; Abe, L.; Brandner, W.; hide

    2012-01-01

    We present high-resolution H-band polarized intensity (FWHM=0".1:14AU) and L'-band imaging data(FWHM= 0".11:15 AU) of the circumstellar disk around the weak-lined T Tauri star PDS 70 in Centaurus at a radial distance of 28 AU (0".2) up to 210 AU (1".5). In both images, a giant inner gap is clearly resolved for the first time, and the radius of the gap is approx.70 AU. Our data show that the geometric center of the disk shifts by approx.6 AU toward the minor axis. We confirm that the brown dwarf companion candidate to the north of PDS 70 is a background star based on its proper motion. As a result of spectral energy distribution fitting by Monte Carlo radiative transfer modeling, we infer the existence of an optically thick inner disk at a few AU. Combining our observations and modeling, we classify the disk of PDS 70 as a pre-transitional disk. Furthermore, based on the analysis of L'-band imaging data, we put an upper limit of approx.30 to approx.50 M(sub J) on the mass of companions within the gap. Taking into account the presence of the large and sharp gap, we suggest that the gap could be formed by dynamical interactions of sub-stellar companions or multiple unseen giant planets in the gap. Key words: planetary systems - polarization - protoplanetary disks - stars: individual (PDS 70) - stars: pre-main sequence.

  3. Preliminary study of Friction disk type turbine for S-CO_2 cycle application (2016 Autumn Meeting of the KNS)

    International Nuclear Information System (INIS)

    Baik, Seungjoon; Heo, Jin Young; Kwon, Jinsu; Lee, Jeong Ik

    2016-01-01

    Among the next generation reactors, a sodium-cooled fast reactor (SFR) with the supercritical carbon dioxide (S-CO_2) Brayton cycle has been suggested as the advanced energy solution. The S-CO_2 power conversion system can achieve high efficiency with the SFR core thermal condition (450-550℃) and also can reduce the total cycle footprint due to high density of the working fluid. Moreover, the S-CO_2 power cycle can reduce the accident consequence compared to the steam Rankine cycle due to the mild sodium-CO_2 interaction. The S-CO_2 power cycle has different characteristic compare to the conventional steam Rankine cycle or gas Brayton cycle. For the turbine section, the expansion ratio is much smaller than the other cycles. Thus, different type of turbine should be evaluated for the advanced S-CO_2 technology and the KAIST research team considered a friction disk type turbine (Tesla turbine) concept for the S-CO_2 cycle applications. In this paper, the test result and analysis of a lab-scale Tesla turbine in the KAIST S-CO_2 experimental facility (S-CO_2PE) are briefly discussed. The KAIST research team investigated a friction disk type turbine, named as Tesla turbine, for the S-CO_2 power cycle applications. The preliminary test of a lab-scale Tesla turbine was conducted with compressed air. The generator, nozzle angle and bearing performances are tested. With the best performing nozzle angle and bearing, the Tesla turbine was tested under various S-CO_2 conditions. As a result, the S-CO_2PE facility generated electricity (0.5-5W). The isentropic efficiency was relatively low (0.8-1.3%). It seemed that, the authors need further study to understand the main mechanism and maximize the efficiency. After developing the design methodology, the design optimization will be conducted to show the applicability of the friction disk type turbine for the S-CO_2 power cycle

  4. Numerical simulations with a FSI-calibrated actuator disk model of wind turbines operating in stratified ABLs

    Science.gov (United States)

    Gohari, S. M. Iman; Sarkar, Sutanu; Korobenko, Artem; Bazilevs, Yuri

    2017-11-01

    Numerical simulations of wind turbines operating under different regimes of stability are performed using LES. A reduced model, based on the generalized actuator disk model (ADM), is implemented to represent the wind turbines within the ABL. Data from the fluid-solid interaction (FSI) simulations of wind turbines have been used to calibrate and validate the reduced model. The computational cost of this method to include wind turbines is affordable and incurs an overhead as low as 1.45%. Using this reduced model, we study the coupling of unsteady turbulent flow with the wind turbine under different ABL conditions: (i) A neutral ABL with zero heat-flux and inversion layer at 350m, in which the incoming wind has the maximum mean shear between the heights of upper-tip and lower-tip; (2) A shallow ABL with surface cooling rate of -1 K/hr wherein the low level jet occurs at the wind turbine hub height. We will discuss how the differences in the unsteady flow between the two ABL regimes impact the wind turbine performance.

  5. Homogeneous Analysis of the Dust Morphology of Transition Disks Observed with ALMA: Investigating Dust Trapping and the Origin of the Cavities

    Science.gov (United States)

    Pinilla, P.; Tazzari, M.; Pascucci, I.; Youdin, A. N.; Garufi, A.; Manara, C. F.; Testi, L.; van der Plas, G.; Barenfeld, S. A.; Canovas, H.; Cox, E. G.; Hendler, N. P.; Pérez, L. M.; van der Marel, N.

    2018-05-01

    We analyze the dust morphology of 29 transition disks (TDs) observed with Atacama Large (sub-)Millimeter Array (ALMA) at (sub-)millimeter emission. We perform the analysis in the visibility plane to characterize the total flux, cavity size, and shape of the ring-like structure. First, we found that the M dust–M ⋆ relation is much flatter for TDs than the observed trends from samples of class II sources in different star-forming regions. This relation demonstrates that cavities open in high (dust) mass disks, independent of the stellar mass. The flatness of this relation contradicts the idea that TDs are a more evolved set of disks. Two potential reasons (not mutually exclusive) may explain this flat relation: the emission is optically thick or/and millimeter-sized particles are trapped in a pressure bump. Second, we discuss our results of the cavity size and ring width in the context of different physical processes for cavity formation. Photoevaporation is an unlikely leading mechanism for the origin of the cavity of any of the targets in the sample. Embedded giant planets or dead zones remain as potential explanations. Although both models predict correlations between the cavity size and the ring shape for different stellar and disk properties, we demonstrate that with the current resolution of the observations, it is difficult to obtain these correlations. Future observations with higher angular resolution observations of TDs with ALMA will help discern between different potential origins of cavities in TDs.

  6. Computational investigation of hydrokinetic turbine arrays in an open channel using an actuator disk-LES model

    Science.gov (United States)

    Kang, Seokkoo; Yang, Xiaolei; Sotiropoulos, Fotis

    2012-11-01

    While a considerable amount of work has focused on studying the effects and performance of wind farms, very little is known about the performance of hydrokinetic turbine arrays in open channels. Unlike large wind farms, where the vertical fluxes of momentum and energy from the atmospheric boundary layer comprise the main transport mechanisms, the presence of free surface in hydrokinetic turbine arrays inhibits vertical transport. To explore this fundamental difference between wind and hydrokinetic turbine arrays, we carry out LES with the actuator disk model to systematically investigate various layouts of hydrokinetic turbine arrays mounted on the bed of a straight open channel with fully-developed turbulent flow fed at the channel inlet. Mean flow quantities and turbulence statistics within and downstream of the arrays will be analyzed and the effect of the turbine arrays as means for increasing the effective roughness of the channel bed will be extensively discussed. This work was supported by Initiative for Renewable Energy & the Environment (IREE) (Grant No. RO-0004-12), and computational resources were provided by Minnesota Supercomputing Institute.

  7. MEANS 2: Microstructure- and Micromechanism-Sensitive Property Models for Advanced Turbine Disk and Blade Systems

    National Research Council Canada - National Science Library

    Pollock, Tresa M; Mills, Michael J

    2008-01-01

    This effort has focused on verification and refinement of the mechanism transitions at intermediate temperatures in the disk alloy Rene 104, with the observation of microtwinning, continuous faulting...

  8. Performance of Partial and Cavity Type Squealer Tip of a HP Turbine Blade in a Linear Cascade

    Directory of Open Access Journals (Sweden)

    Levent Kavurmacioglu

    2018-01-01

    Full Text Available Three-dimensional highly complex flow structure in tip gap between blade tip and casing leads to inefficient turbine performance due to aerothermal loss. Interaction between leakage vortex and secondary flow structures is the substantial source of that loss. Different types of squealer tip geometries were tried in the past, in order to improve turbine efficiency. The current research deals with comparison of partial and cavity type squealer tip concepts for higher aerothermal performance. Effects of squealer tip have been examined comprehensively for an unshrouded HP turbine blade tip geometry in a linear cascade. In the present paper, flow structure through the tip gap was comprehensively investigated by computational fluid dynamic (CFD methods. Numerical calculations were obtained by solving three-dimensional, incompressible, steady, and turbulent form of the Reynolds-averaged Navier-Stokes (RANS equations using a general purpose and three-dimensional viscous flow solver. The two-equation turbulence model, shear stress transport (SST, has been used. The tip profile belonging to the Pennsylvania State University Axial Flow Turbine Research Facility (AFTRF was used to create an extruded solid model of the axial turbine blade. For identifying optimal dimensions of squealer rim in terms of squealer height and squealer width, our previous studies about aerothermal investigation of cavity type squealer tip were utilized. In order to obtain the mesh, an effective parametric generation has been utilized using a multizone structured mesh. Numerical calculations indicate that partial and cavity squealer designs can be effective to reduce the aerodynamic loss and heat transfer to the blade tip. Future efforts will include novel squealer shapes for higher aerothermal performance.

  9. The Mechanical Properties of Candidate Superalloys for a Hybrid Turbine Disk

    Science.gov (United States)

    Gabb, Timothy P.; MacKay, Rebecca A.; Draper, Susan L.; Sudbrack, Chantal K.; Nathal, Michael V.

    2013-01-01

    The mechanical properties of several cast blade superalloys and one powder metallurgy disk superalloy were assessed for potential use in a dual alloy hybrid disk concept of joined dissimilar bore and web materials. Grain size was varied for each superalloy class. Tensile, creep, fatigue, and notch fatigue tests were performed at 704 to 815 degC. Typical microstructures and failure modes were determined. Preferred materials were then selected for future study as the bore and rim alloys in this hybrid disk concept. Powder metallurgy superalloy LSHR at 15 micron grain size and single crystal superalloy LDS-1101+Hf were selected for further study, and future work is recommended to develop the hybrid disk concept.

  10. Fabrication Of Hybird Gas Turbine Disk Material System By Additive Manufacturing Project

    Data.gov (United States)

    National Aeronautics and Space Administration — AM offers the potential to be revolutionary for GRC hybrid disk concept as it: i) bypasses joining through direct deposition or “building” of the PX bore...

  11. Relationship between turbine rotor and disk metallurgical characteristics and stress corrosion cracking behavior. Final report

    International Nuclear Information System (INIS)

    Gayley, H.B.

    1986-09-01

    This report describes stress corrosion test results in which several heats of turbine rotor steels specially prepared to achieve different degrees of segregation to the grain boundaries were tested in concentrated laboratory and actual steam turbine environments. Grain boundary characteristics are considered important because turbine rotor failures in field service have been of an intergranular nature and because grain boundary segregation is known to affect the impact toughness of rotor steels (''temper embrittlement''). The laboratory stress corrosion testing results showed no differences between heavily and lightly segregated test pieces which differed greatly in impact toughness. All test specimens cracked, indicating the laboratory environments may have been too severe to allow differentiation between the various metallurgical conditions, if any differences exist. Test loops and autoclaves for chemical analysis and mechanical testing were designed, installed and are operating in the field testing portion of this program. No intergranular cracking has occurred to date; hence, no differentiation between heavily and lightly segregated test pieces has been possible in field testing. Instrumented crack propagation specimens, which permit measurement of cracking as it occurs, have been installed for the continuing field testing program. Correlation of such cracking with the continuously monitored chemical composition of the environment will increase understanding of the cracking process and may give the possibility of providing an early warning of the existence of conditions which might cause turbine rotor cracking

  12. Propulsion health monitoring of a turbine engine disk using spin test data

    Science.gov (United States)

    Abdul-Aziz, Ali; Woike, Mark; Oza, Nikunj; Matthews, Bryan; Baakilini, George

    2010-03-01

    On line detection techniques to monitor the health of rotating engine components are becoming increasingly attractive options to aircraft engine companies in order to increase safety of operation and lower maintenance costs. Health monitoring remains a challenging feature to easily implement, especially, in the presence of scattered loading conditions, crack size, component geometry and materials properties. The current trend, however, is to utilize noninvasive types of health monitoring or nondestructive techniques to detect hidden flaws and mini cracks before any catastrophic event occurs. These techniques go further to evaluate materials' discontinuities and other anomalies that have grown to the level of critical defects which can lead to failure. Generally, health monitoring is highly dependent on sensor systems that are capable of performing in various engine environmental conditions and able to transmit a signal upon a predetermined crack length, while acting in a neutral form upon the overall performance of the engine system. Efforts are under way at NASA Glenn Research Center through support of the Intelligent Vehicle Health Management Project (IVHM) to develop and implement such sensor technology for a wide variety of applications. These efforts are focused on developing high temperature, wireless, low cost and durable products. Therefore, in an effort to address the technical issues concerning health monitoring of a rotor disk, this paper considers data collected from an experimental study using high frequency capacitive sensor technology to capture blade tip clearance and tip timing measurements in a rotating engine-like-disk-to predict the disk faults and assess its structural integrity. The experimental results collected at a range of rotational speeds from tests conducted at the NASA Glenn Research Center's Rotordynamics Laboratory will be evaluated using multiple data-driven anomaly detection techniques to identify anomalies in the disk. This study

  13. Preliminary study of Friction disk type turbine for S-CO{sub 2} cycle application (2016 Autumn Meeting of the KNS)

    Energy Technology Data Exchange (ETDEWEB)

    Baik, Seungjoon; Heo, Jin Young; Kwon, Jinsu; Lee, Jeong Ik [KAIST, Daejeon (Korea, Republic of)

    2016-10-15

    Among the next generation reactors, a sodium-cooled fast reactor (SFR) with the supercritical carbon dioxide (S-CO{sub 2}) Brayton cycle has been suggested as the advanced energy solution. The S-CO{sub 2} power conversion system can achieve high efficiency with the SFR core thermal condition (450-550℃) and also can reduce the total cycle footprint due to high density of the working fluid. Moreover, the S-CO{sub 2} power cycle can reduce the accident consequence compared to the steam Rankine cycle due to the mild sodium-CO{sub 2} interaction. The S-CO{sub 2} power cycle has different characteristic compare to the conventional steam Rankine cycle or gas Brayton cycle. For the turbine section, the expansion ratio is much smaller than the other cycles. Thus, different type of turbine should be evaluated for the advanced S-CO{sub 2} technology and the KAIST research team considered a friction disk type turbine (Tesla turbine) concept for the S-CO{sub 2} cycle applications. In this paper, the test result and analysis of a lab-scale Tesla turbine in the KAIST S-CO{sub 2} experimental facility (S-CO{sub 2}PE) are briefly discussed. The KAIST research team investigated a friction disk type turbine, named as Tesla turbine, for the S-CO{sub 2} power cycle applications. The preliminary test of a lab-scale Tesla turbine was conducted with compressed air. The generator, nozzle angle and bearing performances are tested. With the best performing nozzle angle and bearing, the Tesla turbine was tested under various S-CO{sub 2} conditions. As a result, the S-CO{sub 2}PE facility generated electricity (0.5-5W). The isentropic efficiency was relatively low (0.8-1.3%). It seemed that, the authors need further study to understand the main mechanism and maximize the efficiency. After developing the design methodology, the design optimization will be conducted to show the applicability of the friction disk type turbine for the S-CO{sub 2} power cycle.

  14. MEANS 2: Microstructure- and Micromechanism-Sensitive Property Models for Advanced Turbine Disk and Blade Systems

    Science.gov (United States)

    2009-12-31

    f„„„,„ -L...-J..— - —I 1 / f+_—=p / —j \\-\\- 4A 14 4A»4 / 4A C4 M / »4.4C A4, «i »A OWOLC $-ISF s - csr !•» ’ML...Materials Society) Publications. 23. S . Ma, L. Carroll and T.M. Pollock, "Development of y Phase Stacking Faults during High Temperature Creep of Ru...into the design of advanced disk and blade systems 6. AUTHOR( S ) Michael J Mills 5. FUNDING NUMBERS FA9550-05-1-0135 7. PERFORMING ORGANIZATION

  15. Probabilistic analysis of bladed turbine disks and the effect of mistuning

    Science.gov (United States)

    Shah, Ashwin; Nagpal, V. K.; Chamis, C. C.

    1990-01-01

    Probabilistic assessment of the maximum blade response on a mistuned rotor disk is performed using the computer code NESSUS. The uncertainties in natural frequency, excitation frequency, amplitude of excitation and damping have been included to obtain the cumulative distribution function (CDF) of blade responses. Advanced mean value first order analysis is used to compute CDF. The sensitivities of different random variables are identified. Effect of the number of blades on a rotor on mistuning is evaluated. It is shown that the uncertainties associated with the forcing function parameters have significant effect on the response distribution of the bladed rotor.

  16. Small vs. large dust grains in transitional disks: do different cavity sizes indicate a planet?. SAO 206462 (HD 135344B) in polarized light with VLT/NACO

    Science.gov (United States)

    Garufi, A.; Quanz, S. P.; Avenhaus, H.; Buenzli, E.; Dominik, C.; Meru, F.; Meyer, M. R.; Pinilla, P.; Schmid, H. M.; Wolf, S.

    2013-12-01

    Context. Transitional disks represent a short stage of the evolution of circumstellar material. Studies of dust grains in these objects can provide pivotal information on the mechanisms of planet formation. Dissimilarities in the spatial distribution of small (μm-size) and large (mm-size) dust grains have recently been pointed out. Aims: Constraints on the small dust grains can be obtained by imaging the distribution of scattered light at near-infrared wavelengths. We aim at resolving structures in the surface layer of transitional disks (with particular emphasis on the inner 10-50 AU), thus increasing the scarce sample of high-resolution images of these objects. Methods: We obtained VLT/NACO near-IR high-resolution polarimetric differential imaging observations of SAO 206462 (HD 135344B). This technique allows one to image the polarized scattered light from the disk without any occulting mask and to reach an inner working angle of ~0.1″. Results: A face-on disk is detected in H and Ks bands between 0.1″ and 0.9″. No significant differences are seen between the H and Ks images. In addition to the spiral arms, these new data allow us to resolve for the first time an inner disk cavity for small dust grains. The cavity size (≃28 AU) is much smaller than what is inferred for large dust grains from (sub-)mm observations (39 to 50 AU). This discrepancy cannot be ascribed to any resolution effect. Conclusions: The interaction between the disk and potential orbiting companion(s) can explain both the spiral arm structure and the discrepant cavity sizes for small and large dust grains. One planet may be carving out the gas (and, thus, the small grains) at 28 AU, and generating a pressure bump at larger radii (39 AU), which holds back the large grains. We analytically estimate that, in this scenario, a single giant planet (with a mass between 5 and 15 MJ) at 17 to 20 AU from the star is consistent with the observed cavity sizes. Based on observations collected at the

  17. Experiments on the Performance of Small Horizontal Axis Wind Turbine with Passive Pitch Control by Disk Pulley

    Directory of Open Access Journals (Sweden)

    Yu-Jen Chen

    2016-05-01

    Full Text Available The present work is to design a passive pitch-control mechanism for small horizontal axis wind turbine (HAWT to generate stable power at high wind speeds. The mechanism uses a disk pulley as an actuator to passively adjust the pitch angle of blades by centrifugal force. For this design, aerodynamic braking is caused by the adjustment of pitch angles at high wind speeds. As a marked advantage, this does not require mechanical brakes that would incur electrical burn-out and structural failure under high speed rotation. This can ensure the survival of blades and generator in sever operation environments. In this paper, the analysis uses blade element momentum theory (BEMT to develop graphical user interface software to facilitate the performance assessment of the small-scale HAWT using passive pitch control (PPC. For verification, the HAWT system was tested in a full-scale wind tunnel for its aerodynamic performance. At low wind speeds, this system performed the same as usual, yet at high wind speeds, the equipped PPC system can effectively reduce the rotational speed to generate stable power.

  18. Lessons learned on shrunk-on disks turbines of the French 900 MWe PWR

    International Nuclear Information System (INIS)

    Calle, P.; Dordonat, M.; Dury, J.P.; Pages, G.; Gras, J.M.; Vaillant, F.; Fillon, R.; Aubry, P.; Bocquet, F.

    1990-01-01

    The LP shrunk-on discs of the 900 MW turbines have been submitted to 2 types of damage: - the fretting-fatigue which affects the housings of anti-rotation keys, of end discs in particular (discs 7 and 14); - the stress-corrosion of the so-called hot discs (3, 4, 5 and the symmetrical ones). Since the current situation of the park is not critical, a policy of revamping could be implemented in order to give the equipment an increased service life without changing the technology. In particular, two kinds of provisions have been taken to fight against the stress-corrosion: on the one hand, protection of the sensitive areas by performing surface treatments and on the other hand, application of constructive modifications intended to avoid containment areas. Besides, the studies associated with these solutions (nickel - plating, shot-blasting) have revealed that they have no negative effects on the corrosion resistance of the base steel. This policy which results from a close collaboration between GEC ALSTHOM and EDF has enabled to avoid any unavailability [fr

  19. A Multi-instrument and Multi-wavelength High Angular Resolution Study of MWC 614: Quantum Heated Particles Inside the Disk Cavity

    Science.gov (United States)

    Kluska, Jacques; Kraus, Stefan; Davies, Claire L.; Harries, Tim; Willson, Matthew; Monnier, John D.; Aarnio, Alicia; Baron, Fabien; Millan-Gabet, Rafael; Ten Brummelaar, Theo; Che, Xiao; Hinkley, Sasha; Preibisch, Thomas; Sturmann, Judit; Sturmann, Laszlo; Touhami, Yamina

    2018-03-01

    High angular resolution observations of young stellar objects are required to study the inner astronomical units of protoplanetary disks in which the majority of planets form. As they evolve, gaps open up in the inner disk regions and the disks are fully dispersed within ∼10 Myr. MWC 614 is a pretransitional object with a ∼10 au radius gap. We present a set of high angular resolution observations of this object including SPHERE/ZIMPOL polarimetric and coronagraphic images in the visible, Keck/NIRC2 near-infrared (NIR) aperture masking observations, and Very Large Telescope Interferometer (AMBER, MIDI, and PIONIER) and Center for High Angular Resolution Astronomy (CLASSIC and CLIMB) long-baseline interferometry at infrared wavelengths. We find that all the observations are compatible with an inclined disk (i ∼ 55° at a position angle of ∼20°–30°). The mid-infrared data set confirms that the disk inner rim is at 12.3 ± 0.4 au from the central star. We determined an upper mass limit of 0.34 M ⊙ for a companion inside the cavity. Within the cavity, the NIR emission, usually associated with the dust sublimation region, is unusually extended (∼10 au, 30 times larger than the theoretical sublimation radius) and indicates a high dust temperature (T ∼ 1800 K). As a possible result of companion-induced dust segregation, quantum heated dust grains could explain the extended NIR emission with this high temperature. Our observations confirm the peculiar state of this object where the inner disk has already been accreted onto the star, exposing small particles inside the cavity to direct stellar radiation. Based on observations made with the Keck observatory (NASA program ID N104N2) and with ESO telescopes at the Paranal Observatory (ESO program IDs 073.C-0720, 077.C-0226, 077.C-0521, 083.C-0984, 087.C-0498(A), 190.C-0963, 095.C-0883) and with the Center for High Angular Resolution Astronomy observatory.

  20. Coupled thermal-fluid analysis with flowpath-cavity interaction in a gas turbine engine

    Science.gov (United States)

    Fitzpatrick, John Nathan

    This study seeks to improve the understanding of inlet conditions of a large rotor-stator cavity in a turbofan engine, often referred to as the drive cone cavity (DCC). The inlet flow is better understood through a higher fidelity computational fluid dynamics (CFD) modeling of the inlet to the cavity, and a coupled finite element (FE) thermal to CFD fluid analysis of the cavity in order to accurately predict engine component temperatures. Accurately predicting temperature distribution in the cavity is important because temperatures directly affect the material properties including Young's modulus, yield strength, fatigue strength, creep properties. All of these properties directly affect the life of critical engine components. In addition, temperatures cause thermal expansion which changes clearances and in turn affects engine efficiency. The DCC is fed from the last stage of the high pressure compressor. One of its primary functions is to purge the air over the rotor wall to prevent it from overheating. Aero-thermal conditions within the DCC cavity are particularly challenging to predict due to the complex air flow and high heat transfer in the rotating component. Thus, in order to accurately predict metal temperatures a two-way coupled CFD-FE analysis is needed. Historically, when the cavity airflow is modeled for engine design purposes, the inlet condition has been over-simplified for the CFD analysis which impacts the results, particularly in the region around the compressor disc rim. The inlet is typically simplified by circumferentially averaging the velocity field at the inlet to the cavity which removes the effect of pressure wakes from the upstream rotor blades. The way in which these non-axisymmetric flow characteristics affect metal temperatures is not well understood. In addition, a constant air temperature scaled from a previous analysis is used as the simplified cavity inlet air temperature. Therefore, the objectives of this study are: (a) model the

  1. Effect of Curved Radial Vane Cavity Arrangements on Predicted Inter-Turbine Burner (ITB) Performance

    Science.gov (United States)

    2007-06-01

    in the cavity, and the vaporization, mixing of fuel and air, and combustion amount of unburned fuel shedding out of the becomes very challenging ...the payoff UUC/ITB concepts becomes critical. UCC/ITB was provided to define the geometry and served flamy hco de wih a ane as the staring point for...for the development and equations for mass, momentum, energy, chemical species, modification of the computer- aided design models, as and turbulence were

  2. Implementation of a generalized actuator disk wind turbine model into the weather research and forecasting model for large-eddy simulation applications

    Energy Technology Data Exchange (ETDEWEB)

    Mirocha, J. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kosovic, B. [National Center for Atmospheric Research, Boulder, CO (United States); Aitken, M. L. [Univ. of Colorado, Boulder, CO (United States); Lundquist, J. K. [Univ. of Colorado, Boulder, CO (United States); National Renewable Energy Lab., Golden, CO (United States)

    2014-01-10

    A generalized actuator disk (GAD) wind turbine parameterization designed for large-eddy simulation (LES) applications was implemented into the Weather Research and Forecasting (WRF) model. WRF-LES with the GAD model enables numerical investigation of the effects of an operating wind turbine on and interactions with a broad range of atmospheric boundary layer phenomena. Numerical simulations using WRF-LES with the GAD model were compared with measurements obtained from the Turbine Wake and Inflow Characterization Study (TWICS-2011), the goal of which was to measure both the inflow to and wake from a 2.3-MW wind turbine. Data from a meteorological tower and two light-detection and ranging (lidar) systems, one vertically profiling and another operated over a variety of scanning modes, were utilized to obtain forcing for the simulations, and to evaluate characteristics of the simulated wakes. Simulations produced wakes with physically consistent rotation and velocity deficits. Two surface heat flux values of 20 W m–2 and 100 W m–2 were used to examine the sensitivity of the simulated wakes to convective instability. Simulations using the smaller heat flux values showed good agreement with wake deficits observed during TWICS-2011, whereas those using the larger value showed enhanced spreading and more-rapid attenuation. This study demonstrates the utility of actuator models implemented within atmospheric LES to address a range of atmospheric science and engineering applications. In conclusion, validated implementation of the GAD in a numerical weather prediction code such as WRF will enable a wide range of studies related to the interaction of wind turbines with the atmosphere and surface.

  3. DARWIN-HC: A Tool to Predict Hot Corrosion of Nickel-Based Turbine Disks, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Hot Corrosion of turbine engine components has been studied for many years. The underlying mechan-isms of Type I Hot Corrosion and Type II Hot Corrosion are...

  4. DARWIN-HC: A Tool to Predict Hot Corrosion of Nickel-Based Turbine Disks, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Hot Corrosion of turbine engine components has been studied for many years. The underlying mechan-isms of Type I Hot Corrosion and Type II Hot Corrosion are...

  5. Investigation of a ceramic vane with a metal disk thermal and mechanical contact in a gas turbine impeller

    Directory of Open Access Journals (Sweden)

    Resnick S.V.

    2015-01-01

    Full Text Available Promising directions of a new generation gas turbine engines development include using in gas turbines ceramic materials blades with high strength, thermal and chemical stability. One of the serious problems in developing such motors is insufficient knowledge of contact phenomena occurring in ceramic and metal details connection nodes. This work presents the numerical modeling results of thermal processes on ceramic and metal details rough boundaries. The investigation results are used in conducting experimental researches in conditions reproducing operating.

  6. Model to calculate mass flow rate and other quantities of two-phase flow in a pipe with a densitometer, a drag disk, and a turbine meter

    International Nuclear Information System (INIS)

    Aya, I.

    1975-11-01

    The proposed model was developed at ORNL to calculate mass flow rate and other quantities of two-phase flow in a pipe when the flow is dispersed with slip between the phases. The calculational model is based on assumptions concerning the characteristics of a turbine meter and a drag disk. The model should be validated with experimental data before being used in blowdown analysis. In order to compare dispersed flow and homogeneous flow, the ratio of readings from each flow regime for each device discussed is calculated for a given mass flow rate and steam quality. The sensitivity analysis shows that the calculated flow rate of a steam-water mixture (based on the measurements of a drag disk and a gamma densitometer in which the flow is assumed to be homogeneous even if there is some slip between phases) is very close to the real flow rate in the case of dispersed flow at a low quality. As the steam quality increases at a constant slip ratio, all models are prone to overestimate. At 20 percent quality the overestimates reach 8 percent in the proposed model, 15 percent in Rouhani's model, 38 percent in homogeneous model, and 75 percent in Popper's model

  7. Vibration of imperfect rotating disk

    Directory of Open Access Journals (Sweden)

    Půst L.

    2011-12-01

    Full Text Available This study is concerned with the theoretical and numerical calculations of the flexural vibrations of a bladed disk. The main focus of this study is to elaborate the basic background for diagnostic and identification methods for ascertaining the main properties of the real structure or an experimental model of turbine disks. The reduction of undesirable vibrations of blades is proposed by using damping heads, which on the experimental model of turbine disk are applied only on a limited number of blades. This partial setting of damping heads introduces imperfection in mass, stiffness and damping distribution on the periphery and leads to more complicated dynamic properties than those of a perfect disk. Calculation of FEM model and analytic—numerical solution of disk behaviour in the limited (two modes frequency range shows the splitting of resonance with an increasing speed of disk rotation. The spectrum of resonance is twice denser than that of a perfect disk.

  8. Effect of Microstructure on Time Dependent Fatigue Crack Growth Behavior In a P/M Turbine Disk Alloy

    Science.gov (United States)

    Telesman, Ignacy J.; Gabb, T. P.; Bonacuse, P.; Gayda, J.

    2008-01-01

    A study was conducted to determine the processes which govern hold time crack growth behavior in the LSHR disk P/M superalloy. Nineteen different heat treatments of this alloy were evaluated by systematically controlling the cooling rate from the supersolvus solutioning step and applying various single and double step aging treatments. The resulting hold time crack growth rates varied by more than two orders of magnitude. It was shown that the associated stress relaxation behavior for these heat treatments was closely correlated with the crack growth behavior. As stress relaxation increased, the hold time crack growth resistance was also increased. The size of the tertiary gamma' in the general microstructure was found to be the key microstructural variable controlling both the hold time crack growth behavior and stress relaxation. No relationship between the presence of grain boundary M23C6 carbides and hold time crack growth was identified which further brings into question the importance of the grain boundary phases in determining hold time crack growth behavior. The linear elastic fracture mechanics parameter, Kmax, is unable to account for visco-plastic redistribution of the crack tip stress field during hold times and thus is inadequate for correlating time dependent crack growth data. A novel methodology was developed which captures the intrinsic crack driving force and was able to collapse hold time crack growth data onto a single curve.

  9. Blades and disks in gas turbines. Material and component behaviour. Project department D. Final report; Schaufeln und Scheiben in Gasturbinen. Werkstoff- und Bauteilverhalten. Projektbereich D. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-04-01

    The Special Research Department No. 339, ``Disks and Blades in Gas Turbines - Material and Component Characteristics`` received financial support from 1988 through 1996. This final report discusses activities of the years 1994, 1995, and 1996. Project group D, ``Production and Quality Assurance``, investigated rotors and blades. Grinding techniques were developed and optimized for nickel base materials, and the effects of grinding on the marginal zones was investigated, including an analysis of intrinsic stresses induced by machining. In the field of ceramics, separation and production of reinforced ceramics was investigated, and techniques for vacuum soldering of ceramic/ceramic and ceramic/metal compounds for high-temperature applications were developed. In the framework of a part-project carried out at HMI, neutron diffraction was used for nondestructive analysis of volume intrinsic stresses near the joint both on model geometries and on the joint between metal shaft and ceramic rotor. The development and application of computerized tomography for testing of ceramic rotors and joints was an important contribution to quality assurance. (orig./MM) [Deutsch] Der Sonderforschungsbereich 339 `Schaufeln und Scheiben in Gasturbinen - Werkstoff- und Bauteilverhalten` wurde von 1988 bis Ende 1996 gefoerdert. Der vorliegende Abschlussbericht behandelt vor allem die Arbeiten der Jahre 1994, 1995 und 1996. Am Bauteil Rotor und Schaufel orientierten sich die Arbeiten des Projektbereichs D `Fertigung und Qualitaetssicherung`. Zum einen wurden hier Schleifverfahren fuer Nickelbasis-Werkstoffe entwickelt und optimiert und der Einfluss der Schleifbearbeitung auf die Randzoneneigenschaften studiert. Zur Randzonencharakterisierung gehoerte insbesondere auch die Analyse bearbeitungsinduzierter Eigenspannungen. Auf der Seite der Keramiken wurde zum einen die trennende Fertigung verstaerkter Keramiken untersucht. Zum anderen wurden Techniken fuer das Hochvakuumloeten von Keramik

  10. Evaluation of powder metallurgy superalloy disk materials

    Science.gov (United States)

    Evans, D. J.

    1975-01-01

    A program was conducted to develop nickel-base superalloy disk material using prealloyed powder metallurgy techniques. The program included fabrication of test specimens and subscale turbine disks from four different prealloyed powders (NASA-TRW-VIA, AF2-1DA, Mar-M-432 and MERL 80). Based on evaluation of these specimens and disks, two alloys (AF2-1DA and Mar-M-432) were selected for scale-up evaluation. Using fabricating experience gained in the subscale turbine disk effort, test specimens and full scale turbine disks were formed from the selected alloys. These specimens and disks were then subjected to a rigorous test program to evaluate their physical properties and determine their suitability for use in advanced performance turbine engines. A major objective of the program was to develop processes which would yield alloy properties that would be repeatable in producing jet engine disks from the same powder metallurgy alloys. The feasibility of manufacturing full scale gas turbine engine disks by thermomechanical processing of pre-alloyed metal powders was demonstrated. AF2-1DA was shown to possess tensile and creep-rupture properties in excess of those of Astroloy, one of the highest temperature capability disk alloys now in production. It was determined that metallographic evaluation after post-HIP elevated temperature exposure should be used to verify the effectiveness of consolidation of hot isostatically pressed billets.

  11. Composite turbine bucket assembly

    Science.gov (United States)

    Liotta, Gary Charles; Garcia-Crespo, Andres

    2014-05-20

    A composite turbine blade assembly includes a ceramic blade including an airfoil portion, a shank portion and an attachment portion; and a transition assembly adapted to attach the ceramic blade to a turbine disk or rotor, the transition assembly including first and second transition components clamped together, trapping said ceramic airfoil therebetween. Interior surfaces of the first and second transition portions are formed to mate with the shank portion and the attachment portion of the ceramic blade, and exterior surfaces of said first and second transition components are formed to include an attachment feature enabling the transition assembly to be attached to the turbine rotor or disk.

  12. Premixed direct injection disk

    Science.gov (United States)

    York, William David; Ziminsky, Willy Steve; Johnson, Thomas Edward; Lacy, Benjamin; Zuo, Baifang; Uhm, Jong Ho

    2013-04-23

    A fuel/air mixing disk for use in a fuel/air mixing combustor assembly is provided. The disk includes a first face, a second face, and at least one fuel plenum disposed therebetween. A plurality of fuel/air mixing tubes extend through the pre-mixing disk, each mixing tube including an outer tube wall extending axially along a tube axis and in fluid communication with the at least one fuel plenum. At least a portion of the plurality of fuel/air mixing tubes further includes at least one fuel injection hole have a fuel injection hole diameter extending through said outer tube wall, the fuel injection hole having an injection angle relative to the tube axis. The invention provides good fuel air mixing with low combustion generated NOx and low flow pressure loss translating to a high gas turbine efficiency, that is durable, and resistant to flame holding and flash back.

  13. Studying the effect of the shape parameters on the performance of the darrieus wind turbine using the multiple double disk stream tube theory

    International Nuclear Information System (INIS)

    Elmabrok, Ali Mohamed; Al-makhlufi, Ahmed A.

    2006-01-01

    The performance of the Darrieus vertical axis turbine is comparable with that of the more common horizontal axis machines. It has a number of aerodynamic and structural advantages over HAWTS. However the darrieus turbines are not self-starting at low wind speeds which is a considerable disadvantage for a simple small scale installation. Generally, papers concerning vertical axis turbine do not study the behavior of the rotor at low tip speed ratios. Therefore they do not deal with the self starting problems. A number of analytical methods were investigated to see whether they could predict the starting performance of vertical axis turbines. The chosen methods and 'actuator disc theory' for multiple stream tubes. In this paper the multiple stream tube model is applied using two discs in tandem. The computational analysis of all models simulates the blade aerodynamics throughout the full range of incidence from 180 degree centigrade. The effects of varying various geometric parameters of the windmill upon the performance of the rotor are investigated to find a design with improved self starting characteristics. The best agreement between theory and experiment was obtained using the multiple stream tube (double disc) models.(Author)

  14. Integrated circuit cooled turbine blade

    Science.gov (United States)

    Lee, Ching-Pang; Jiang, Nan; Um, Jae Y.; Holloman, Harry; Koester, Steven

    2017-08-29

    A turbine rotor blade includes at least two integrated cooling circuits that are formed within the blade that include a leading edge circuit having a first cavity and a second cavity and a trailing edge circuit that includes at least a third cavity located aft of the second cavity. The trailing edge circuit flows aft with at least two substantially 180-degree turns at the tip end and the root end of the blade providing at least a penultimate cavity and a last cavity. The last cavity is located along a trailing edge of the blade. A tip axial cooling channel connects to the first cavity of the leading edge circuit and the penultimate cavity of the trailing edge circuit. At least one crossover hole connects the penultimate cavity to the last cavity substantially near the tip end of the blade.

  15. Turbomachine Sealing and Secondary Flows - Part 3. Part 3; Review of Power-Stream Support, Unsteady Flow Systems, Seal and Disk Cavity Flows, Engine Externals, and Life and Reliability Issues

    Science.gov (United States)

    Hendricks, R. C.; Steinetz, B. M.; Zaretsky, E. V.; Athavale, M. M.; Przekwas, A. J.

    2004-01-01

    The issues and components supporting the engine power stream are reviewed. It is essential that companies pay close attention to engine sealing issues, particularly on the high-pressure spool or high-pressure pumps. Small changes in these systems are reflected throughout the entire engine. Although cavity, platform, and tip sealing are complex and have a significant effect on component and engine performance, computational tools (e.g., NASA-developed INDSEAL, SCISEAL, and ADPAC) are available to help guide the designer and the experimenter. Gas turbine engine and rocket engine externals must all function efficiently with a high degree of reliability in order for the engine to run but often receive little attention until they malfunction. Within the open literature statistically significant data for critical engine components are virtually nonexistent; the classic approach is deterministic. Studies show that variations with loading can have a significant effect on component performance and life. Without validation data they are just studies. These variations and deficits in statistical databases require immediate attention.

  16. Forging Long Shafts On Disks

    Science.gov (United States)

    Tilghman, Chris; Askey, William; Hopkins, Steven

    1989-01-01

    Isothermal-forging apparatus produces long shafts integral with disks. Equipment based on modification of conventional isothermal-forging equipment, required stroke cut by more than half. Enables forging of shafts as long as 48 in. (122 cm) on typical modified conventional forging press, otherwise limited to making shafts no longer than 18 in. (46cm). Removable punch, in which forged material cools after plastic deformation, essential novel feature of forging apparatus. Technology used to improve such products as components of gas turbines and turbopumps and of other shaft/disk parts for powerplants, drive trains, or static structures.

  17. Gas turbine

    International Nuclear Information System (INIS)

    Yang, Ok Ryong

    2004-01-01

    This book introduces gas turbine cycle explaining general thing of gas turbine, full gas turbine cycle, Ericson cycle and Brayton cycle, practical gas turbine cycle without pressure loss, multiaxial type gas turbine cycle and special gas turbine cycle, application of basic theory on a study on suction-cooling gas turbine cycle with turbo-refrigerating machine using the bleed air, and general performance characteristics of the suction-cooling gas turbine cycle combined with absorption-type refrigerating machine.

  18. New Insights into the Nature of Transition Disks from a Complete Disk Survey of the Lupus Star-forming Region

    Science.gov (United States)

    van der Marel, Nienke; Williams, Jonathan P.; Ansdell, M.; Manara, Carlo F.; Miotello, Anna; Tazzari, Marco; Testi, Leonardo; Hogerheijde, Michiel; Bruderer, Simon; van Terwisga, Sierk E.; van Dishoeck, Ewine F.

    2018-02-01

    Transition disks with large dust cavities around young stars are promising targets for studying planet formation. Previous studies have revealed the presence of gas cavities inside the dust cavities, hinting at recently formed, giant planets. However, many of these studies are biased toward the brightest disks in the nearby star-forming regions, and it is not possible to derive reliable statistics that can be compared with exoplanet populations. We present the analysis of 11 transition disks with large cavities (≥20 au radius) from a complete disk survey of the Lupus star-forming region, using ALMA Band 7 observations at 0.″3 (22–30 au radius) resolution of the 345 GHz continuum, 13CO and C18O 3–2 observations, and the spectral energy distribution of each source. Gas and dust surface density profiles are derived using the physical–chemical modeling code DALI. This is the first study of transition disks of large cavities within a complete disk survey within a star-forming region. The dust cavity sizes range from 20 to 90 au radius, and in three cases, a gas cavity is resolved as well. The deep drops in gas density and large dust cavity sizes are consistent with clearing by giant planets. The fraction of transition disks with large cavities in Lupus is ≳ 11 % , which is inconsistent with exoplanet population studies of giant planets at wide orbits. Furthermore, we present a hypothesis of an evolutionary path for large massive disks evolving into transition disks with large cavities.

  19. Video Toroid Cavity Imager

    Energy Technology Data Exchange (ETDEWEB)

    Gerald, Rex E. II; Sanchez, Jairo; Rathke, Jerome W.

    2004-08-10

    A video toroid cavity imager for in situ measurement of electrochemical properties of an electrolytic material sample includes a cylindrical toroid cavity resonator containing the sample and employs NMR and video imaging for providing high-resolution spectral and visual information of molecular characteristics of the sample on a real-time basis. A large magnetic field is applied to the sample under controlled temperature and pressure conditions to simultaneously provide NMR spectroscopy and video imaging capabilities for investigating electrochemical transformations of materials or the evolution of long-range molecular aggregation during cooling of hydrocarbon melts. The video toroid cavity imager includes a miniature commercial video camera with an adjustable lens, a modified compression coin cell imager with a fiat circular principal detector element, and a sample mounted on a transparent circular glass disk, and provides NMR information as well as a video image of a sample, such as a polymer film, with micrometer resolution.

  20. High temperature turbine engine structure

    Energy Technology Data Exchange (ETDEWEB)

    Carruthers, W.D.; Boyd, G.L.

    1993-07-20

    A hybrid ceramic/metallic gas turbine is described comprising; a housing defining an inlet, an outlet, and a flow path communicating the inlet with the outlet for conveying a flow of fluid through the housing, a rotor member journaled by the housing in the flow path, the rotor member including a compressor rotor portion rotatively inducting ambient air via the inlet and delivering this air pressurized to the flow path downstream of the compressor rotor, a combustor disposed in the flow path downstream of the compressor receiving the pressurized air along with a supply of fuel to maintain combustion providing a flow of high temperature pressurized combustion products in the flow path downstream thereof, the rotor member including a turbine rotor portion disposed in the flow path downstream of the combustor and rotatively expanding the combustion products toward ambient for flow from the turbine engine via the outlet, the turbine rotor portion providing shaft power driving the compressor rotor portion and an output shaft portion of the rotor member, a disk-like metallic housing portion journaling the rotor member to define a rotational axis therefore, and a disk-like annular ceramic turbine shroud member bounding the flow path downstream of the combustor and circumscribing the turbine rotor portion to define a running clearance therewith, the disk-like ceramic turbine shroud member having a reference axis coaxial with the rotational axis and being spaced axially from the metallic housing portion in mutually parallel concentric relation therewith and a plurality of spacers disposed between ceramic disk-like shroud member and the metallic disk-like housing portion and circumferentially spaced apart, each of the spacers having a first and second end portion having an end surface adjacent the shroud member and the housing portion respectively, the end surfaces having a cylindrical curvature extending transversely relative to the shroud member and the housing portion.

  1. Flow visualizations, velocity measurements, and surface convection measurements in simulated 20.8-cm Nova box amplifier cavities

    International Nuclear Information System (INIS)

    Julien, J.L.; Molishever, E.L.

    1983-01-01

    Reported are fluid mechanics experiments performed in models of the 20.8-cm Nova amplifier lamp and disk cavities. Lamp cavity nitrogen flows are shown, by both flow visualization and velocity measurements, to be acceptably uniform and parallel to the flashlamps. In contrast, the nitrogen flows in the disk cavity are shown to be disordered. Even though disk cavity flows are disordered, the simplest of three proposed nitrogen introduction systems for the disk cavity was found to be acceptable based on convection measurements made at the surfaces of simulated laser disks

  2. Dental cavities

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/001055.htm Dental cavities To use the sharing features on this page, please enable JavaScript. Dental cavities are holes (or structural damage) in the ...

  3. Turbinate surgery

    Science.gov (United States)

    Turbinectomy; Turbinoplasty; Turbinate reduction; Nasal airway surgery; Nasal obstruction - turbinate surgery ... There are several types of turbinate surgery: Turbinectomy: All or ... This can be done in several different ways, but sometimes a ...

  4. Frequency modulation of semiconductor disk laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Zolotovskii, I O; Korobko, D A; Okhotnikov, O G [Ulyanovsk State University, Ulyanovsk (Russian Federation)

    2015-07-31

    A numerical model is constructed for a semiconductor disk laser mode-locked by a semiconductor saturable absorber mirror (SESAM), and the effect that the phase modulation caused by gain and absorption saturation in the semiconductor has on pulse generation is examined. The results demonstrate that, in a laser cavity with sufficient second-order dispersion, alternating-sign frequency modulation of pulses can be compensated for. We also examine a model for tuning the dispersion in the cavity of a disk laser using a Gires–Tournois interferometer with limited thirdorder dispersion. (control of radiation parameters)

  5. Braking System for Wind Turbines

    Science.gov (United States)

    Krysiak, J. E.; Webb, F. E.

    1987-01-01

    Operating turbine stopped smoothly by fail-safe mechanism. Windturbine braking systems improved by system consisting of two large steel-alloy disks mounted on high-speed shaft of gear box, and brakepad assembly mounted on bracket fastened to top of gear box. Lever arms (with brake pads) actuated by spring-powered, pneumatic cylinders connected to these arms. Springs give specific spring-loading constant and exert predetermined load onto brake pads through lever arms. Pneumatic cylinders actuated positively to compress springs and disengage brake pads from disks. During power failure, brakes automatically lock onto disks, producing highly reliable, fail-safe stops. System doubles as stopping brake and "parking" brake.

  6. Can disk be removed in a disk-and-washer structure

    International Nuclear Information System (INIS)

    Inagaki, Shigemi.

    1981-06-01

    A modified disk-and-washer structure, so to speak a coaxial coupled cavity structure, is proposed. It has not protrusions called disks at the inner surface of the cylinder. The thickness of the washer outer rim increases so much that it rather looks like a chain of accelerating cavities having slit around the outermost wall and through the slit they are coupled in a cylindrical cavity. SUPERFISH calculations show that both accelerating and coupling mode can be made confluent** in π-mode* operation and that the effective shunt impedance obtained under certain condition is 27 Mohm/m which is 10% less than that of KEK PF single cavity or scaled LASL side-coupled cavity. (author)

  7. Advanced LP turbine blade design

    International Nuclear Information System (INIS)

    Jansen, M.; Pfeiffer, R.; Termuehlen, H.

    1990-01-01

    In the 1960's and early 1970's, the development of steam turbines for the utility industry was mainly influenced by the demand for increasing unit sizes. Nuclear plants in particular, required the design of LP turbines with large annulus areas for substantial mass and volumetric steam flows. Since then the development of more efficient LP turbines became an ongoing challenge. Extensive R and D work was performed in order to build efficient and reliable LP turbines often exposed to severe corrosion, erosion and dynamic excitation conditions. This task led to the introduction of an advanced disk-type rotor design for 1800 rpm LP turbines and the application of a more efficient, reaction-type blading for all steam turbine sections including the first stages of LP turbines. The most recent developments have resulted in an advanced design of large LP turbine blading, typically used in the last three stages of each LP turbine flow section. Development of such blading required detailed knowledge of the three dimensional, largely transonic, flow conditions of saturated steam. Also the precise assessment of blade stressing from dynamic conditions, such as speed and torsional resonance, as well as stochastic and aerodynamic excitation is of extreme importance

  8. Modeling Protoplanetary Disks to Characterize the Evolution of their Structure

    Science.gov (United States)

    Allen, Magdelena; van der Marel, Nienke; Williams, Jonathan

    2018-01-01

    Stars form from gravitationally collapsing clouds of gas and dust. Most young stars retain a protoplanetary disk for a few million years. This disk’s dust reemits stellar flux in the infrared, producing a spectral energy distribution (SED) observable by Spitzer and other telescopes. To understand the inner clearing of dust cavities and evolution in the SED, we used the Chiang & Goldreich two-layer approximation. We first wrote a python script based on refinements by Dullemond that includes a hot, puffed inner rim, shadowed mid region, flaring outer disk, and a variable inner cavity. This was then coupled with a Markov Chain Monte Carlo procedure to fit the observed SEDs of disks in the star forming Lupus region. The fitting procedure recovers physical characteristics of the disk including temperature, size, mass, and surface density. We compare the characteristics of circumstellar disks without holes and more evolved transition disks with cleared inner regions.

  9. Vortex capturing vertical axis wind turbine

    International Nuclear Information System (INIS)

    Zannetti, L; Gallizio, F; Ottino, G

    2007-01-01

    An analytical-numerical study is presented for an innovative lift vertical axis turbine whose blades are designed with vortex trapping cavities that act as passive flow control devices. The unsteady flow field past one-bladed and two-bladed turbines is described by a combined analytical and numerical method based on conformal mapping and on a blob vortex method

  10. Research overview on vibration damping of mistuned bladed disk assemblies

    Directory of Open Access Journals (Sweden)

    Liang ZHANG

    2016-04-01

    Full Text Available Bladed disk assemblies are very important parts in auto engine and gas turbine, and is widely used in practical engineering. The mistuning existing commonly in the bladed disk assemblies can destroy the vibration characteristics of the bladed disk assemblies, which is one of the reasons for the high cycle fatigue failure of bladed disk assemblies, so it is necessary to research how to reduce the vibration of the bladed disk assemblies. On the basis of the review of relevant research at home and abroad, the mistuning vibration mechanism of the bladed disk assemblies is introduced, and the main technical methods of the vibration damping of bladed disk assemblies are reviewed, such as artificially active mistuning, collision damping, friction damping and optimization of the blade position. Some future research directions are presented.

  11. Advanced LP turbine installation at 1300 MW nuclear power station Unterweser

    International Nuclear Information System (INIS)

    Jacobsen, G.; Oeynhausen, H.; Termuehlen, H.

    1991-01-01

    This paper reports on Preussen Elektra AG's Unterweser power plant. The steam turbine-generator features a disk-type LP turbine rotor design developed in the late 1960's to early 1970's. This rotor design has been installed in 19 nuclear power plants. The 47 rotors in these plants have been in operation for an average of almost 10 years. The design of the 1970 vintage nuclear LP turbine rotors was based on extensive experience gained with disk-type rotors of fossil turbines built in the 1950's. When EPRI reported about corrosion cracking in nuclear LP turbines, a program was initiated by Siemens/KWU as original steam turbine supplier to ultrasonically inspect all their disk-type rotors in nuclear power plats. Indications on one rotor disk in the Unterweser plant was found. This single event was the only one found out of 310 disks inspected in nuclear power plants

  12. Cavity flows. Fluids engineering conference, Minneapolis, MN, May 5--7, 1975

    International Nuclear Information System (INIS)

    Parkin, B.R.; Morgan, W.B.

    1975-01-01

    The fifteen papers given at the cavity flow conference are presented. Information is included on cavitation flow experiments with propeller blades, turbines, turbopumps, and hydrofoils, and theoretical studies of the characteristics and effects of cavity flows

  13. Report on the achievements in fiscal 1998. Hydrogen utilizing international clean energy system technology (WE-NET). Subtask 8. Development of hydrogen combustion turbine (development of major components such as turbine blades and rotors); 1998 nendo suiso riyo kokusai clean energy system gijutsu (WE-NET). 8. Suiso nensho turbine no kaihatsu (turbine yoku, rotor nado shuyo kosei kiki no kaihatsu)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-03-01

    The present research and development is intended to establish the fundamental technologies required to develop a pilot plant, by investigating development of such major component devices as turbine blades and rotors in a hydrogen combustion turbine. In the turbine moving and stator blade cooling technology, it is intended to achieve the power plant efficiency of 60% (based on HHV) as established in the interim evaluation performed in fiscal 1996. Therefore, the necessary element tests, detailed blade design, and partial fabrication were moved forward on the three kinds of the selected blade cooling systems as the cooling systems that can deal with the steam temperature condition as high as 1,700 degrees C. Fiscal 1998 will execute the design and fabrication of test blades and testing devices for blade cooling evaluation tests to be performed at Tashiro Township in Akita Prefecture. At the same time, evaluation and selection will be made on the three kinds of the cooling blades. In the rotor cooling technology, for the purpose of analyzing the rolling-in phenomenon of steam in the main turbine flow, a method will be developed to analyze rotor disk cavity temperatures based on CFD, the basic sealing conditions based thereon will be discussed, and generalization will be made on the rotor cooling technology. (NEDO)

  14. An analytic approach to optimize tidal turbine fields

    Science.gov (United States)

    Pelz, P.; Metzler, M.

    2013-12-01

    Motivated by global warming due to CO2-emission various technologies for harvesting of energy from renewable sources are developed. Hydrokinetic turbines get applied to surface watercourse or tidal flow to gain electrical energy. Since the available power for hydrokinetic turbines is proportional to the projected cross section area, fields of turbines are installed to scale shaft power. Each hydrokinetic turbine of a field can be considered as a disk actuator. In [1], the first author derives the optimal operation point for hydropower in an open-channel. The present paper concerns about a 0-dimensional model of a disk-actuator in an open-channel flow with bypass, as a special case of [1]. Based on the energy equation, the continuity equation and the momentum balance an analytical approach is made to calculate the coefficient of performance for hydrokinetic turbines with bypass flow as function of the turbine head and the ratio of turbine width to channel width.

  15. Preparation of thin actinide metal disks using a multiple disk casting technique

    International Nuclear Information System (INIS)

    Conner, W.V.

    1975-01-01

    A casting technique has been developed for preparing multiple actinide metal disks which have a minimum thickness of 0.006 inch. This technique was based on an injection casting procedure which utilizes the weight of a tantalum metal rod to force the molten metal into the mold cavity. Using the proper mold design and casting parameters, it has been possible to prepare ten 1/2 inch diameter neptunium or plutonium metal disks in a single casting, This casting technique is capable of producing disks which are very uniform. The average thickness of the disks from a typical casting will vary no more than 0.001 inch and the variation in the thickness of the individual disks will range from 0.0001 to 0.0005 inch. (Auth.)

  16. Preparation of thin actinide metal disks using a multiple disk casting technique

    International Nuclear Information System (INIS)

    Conner, W.V.

    1976-01-01

    A casting technique has been developed for preparing multiple actinide metal disks which have a minimum thickness of 0.006 inch. This technique was based on an injection casting procedure which utilizes the weight of a tantalum metal rod to force the molten metal into the mold cavity. Using the proper mold design and casting parameters, it has been possible to prepare ten 1/2 inch diameter neptunium or plutonium metal disks in a single casting. This casting technique is capable of producing disks which are very uniform. The average thickness of the disks from a typical casting will vary no more than 0.001 inch and the variation in the thickness of the individual disks will range from 0.0001 to 0.0005 inch. (author)

  17. Bimetallic Blisks with Shrouded Turbine Blades for Gas Turbine Engines

    Directory of Open Access Journals (Sweden)

    L. A. Magerramova

    2015-01-01

    Full Text Available The paper discusses prospects of using blisks with shrouded blades. Increasing an engine life and efficiency as well as mass reduction can also be achieved by increasing blade numbers and decreasing disk diameter. But design engineers are faced with the problem of blade placement because of the disk size and root dimensions.The problem of increasing life and cyclic durability, vibration strength, and lightweight design of the turbine gas turbine wheels, can be solved by an elimination of blade - disk locks.The technology of manufacturing one-piece blisks by connecting the blades with the disc part using hot isostatic pressing was developed. This technology allows us to use blades with shrouds. It is necessary to increase efficiency and to improve high cycle fatigue performance of rotor blades.One of the pressing problems is to ensure the necessary position of shrouds in relation to each other in the manufacturing process as well as in the service. Numerical studies of the influence of the shroud mounting position on blade strength during operation allowed us to develop a methodology of choosing a shroud mounting position.Based on the two turbine wheels (LPT and HPT calculations advantages of blisk design with respect to the lock-based design were shown. Application of bimetallic blisks with shrouded blades resulted in a lifespan increase and weight reduction.In addition, other advantages of blisk design are as follows: possible reduction in the number of parts, elimination of leaks and fretting that take place in the blade - disk locks, exception of expensive broaching operations and disk alloy saving. The shortcoming is elimination of damping in root connection. In addition, there are no widely used repair methods.Despite these disadvantages the usage of bimetallic turbine blisks with shrouded blades is very promising.

  18. accelerating cavity

    CERN Multimedia

    On the inside of the cavity there is a layer of niobium. Operating at 4.2 degrees above absolute zero, the niobium is superconducting and carries an accelerating field of 6 million volts per metre with negligible losses. Each cavity has a surface of 6 m2. The niobium layer is only 1.2 microns thick, ten times thinner than a hair. Such a large area had never been coated to such a high accuracy. A speck of dust could ruin the performance of the whole cavity so the work had to be done in an extremely clean environment.

  19. radiofrequency cavity

    CERN Multimedia

    1988-01-01

    The pulse of a particle accelerator. 128 of these radio frequency cavities were positioned around CERN's 27-kilometre LEP ring to accelerate electrons and positrons. The acceleration was produced by microwave electric oscillations at 352 MHz. The electrons and positrons were grouped into bunches, like beads on a string, and the copper sphere at the top stored the microwave energy between the passage of individual bunches. This made for valuable energy savings as it reduced the heat generated in the cavity.

  20. The Study the Vibration Condition of the Blade of the Gas Turbine Engine with an All-metal Wire Rope Damper in the Area Mount of the Blade to the Disk

    Science.gov (United States)

    Melentjev, Vladimir S.; Gvozdev, Alexander S.

    2018-01-01

    Improving the reliability of modern turbine engines is actual task. This is achieved due to prevent a vibration damage of the operating blades. On the department of structure and design of aircraft engines have accumulated a lot of experimental data on the protection of the blades of the gas turbine engine from a vibration. In this paper we proposed a method for calculating the characteristics of wire rope dampers in the root attachment of blade of a gas turbine engine. The method is based on the use of the finite element method and transient analysis. Contact interaction (Lagrange-Euler method) between the compressor blade and the disc of the rotor has been taken into account. Contribution of contact interaction between details in damping of the system was measured. The proposed method provides a convenient way for the iterative selection of the required parameters the wire rope elastic-damping element. This element is able to provide the necessary protection from the vibration for the blade of a gas turbine engine.

  1. Hydraulic turbines

    International Nuclear Information System (INIS)

    Meluk O, G.

    1998-01-01

    The hydraulic turbines are defined according to the specific speed, in impulse turbines and in reaction turbines. Currently, the Pelton turbines (of impulse) and the Francis and Kaplan turbines (of reaction), they are the most important machines in the hydroelectric generation. The hydraulic turbines are capable of generating in short times, large powers, from its loads zero until the total load and reject the load instantly without producing damages in the operation. When the hydraulic resources are important, the hydraulic turbines are converted in the axle of the electric system. Its combination with thermoelectric generation systems, it allow the continuing supply of the variations in demand of energy system. The available hydraulic resource in Colombia is of 93085 MW, of which solely 9% is exploited, become 79% of all the electrical country generation, 21% remaining is provided by means of the thermoelectric generation

  2. Heat generation by a wind turbine

    Energy Technology Data Exchange (ETDEWEB)

    Corten, G.P. [ECN Wind, Petten (Netherlands)

    2001-01-01

    It will be shown that an actuator disk operating in wind turbine mode extracts more energy from the fluid than can be transferred into useful energy. At the Lanchester-Betz limit the decrease of the kinetic energy in the wind is converted by 2 /3 into useful power and by 1 /3 into heat. Behind the wind turbine the outer flow and the flow that has passed the actuator disk will mix. In this process momentum is conserved but part of the kinetic energy will dissipate in heat via viscous shear. 7 refs.

  3. Wireless In-situ Nondestructive Inspection of Engine Rotor Disks with Ultrasonic Guided Waves, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The structural integrity of jet engine turbine or fan rotor disks is vital for aviation safety. Cumulative cracks at critical loading and high stress areas, if not...

  4. Wireless In-situ Nondestructive Inspection of Engine Rotor Disks with Ultrasonic Guided Waves, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The integrity of rotor disks in engine turbines or fans is vital to aviation safety. Cumulative cracks at critical loading and high stress areas, if not detected and...

  5. Oscillations of disks

    CERN Document Server

    Kato, Shoji

    2016-01-01

    This book presents the current state of research on disk oscillation theory, focusing on relativistic disks and tidally deformed disks. Since the launch of the Rossi X-ray Timing Explorer (RXTE) in 1996, many high-frequency quasiperiodic oscillations (HFQPOs) have been observed in X-ray binaries. Subsequently, similar quasi-periodic oscillations have been found in such relativistic objects as microquasars, ultra-luminous X-ray sources, and galactic nuclei. One of the most promising explanations of their origin is based on oscillations in relativistic disks, and a new field called discoseismology is currently developing. After reviewing observational aspects, the book presents the basic characteristics of disk oscillations, especially focusing on those in relativistic disks. Relativistic disks are essentially different from Newtonian disks in terms of several basic characteristics of their disk oscillations, including the radial distributions of epicyclic frequencies. In order to understand the basic processes...

  6. Turbine bucket for use in gas turbine engines and methods for fabricating the same

    Science.gov (United States)

    Garcia-Crespo, Andres

    2014-06-03

    A turbine bucket for use with a turbine engine. The turbine bucket includes an airfoil that extends between a root end and a tip end. The airfoil includes an outer wall that defines a cavity that extends from the root end to the tip end. The outer wall includes a first ceramic matrix composite (CMC) substrate that extends a first distance from the root end to the tip end. An inner wall is positioned within the cavity. The inner wall includes a second CMC substrate that extends a second distance from the root end towards the tip end that is different than the first distance.

  7. MIGRATION TRAPS IN DISKS AROUND SUPERMASSIVE BLACK HOLES

    International Nuclear Information System (INIS)

    Bellovary, Jillian M.; Low, Mordecai-Mark Mac; McKernan, Barry; Ford, K. E. Saavik

    2016-01-01

    Accretion disks around supermassive black holes (SMBHs) in active galactic nuclei (AGNs) contain stars, stellar mass black holes, and other stellar remnants, which perturb the disk gas gravitationally. The resulting density perturbations exert torques on the embedded masses causing them to migrate through the disk in a manner analogous to planets in protoplanetary disks. We determine the strength and direction of these torques using an empirical analytic description dependent on local disk gradients, applied to two different analytic, steady-state disk models of SMBH accretion disks. We find that there are radii in such disks where the gas torque changes sign, trapping migrating objects. Our analysis shows that major migration traps generally occur where the disk surface density gradient changes sign from positive to negative, around 20–300R g , where R g  = 2GM/c 2 is the Schwarzschild radius. At these traps, massive objects in the AGN disk can accumulate, collide, scatter, and accrete. Intermediate mass black hole formation is likely in these disk locations, which may lead to preferential gap and cavity creation at these radii. Our model thus has significant implications for SMBH growth as well as gravitational wave source populations

  8. MIGRATION TRAPS IN DISKS AROUND SUPERMASSIVE BLACK HOLES

    Energy Technology Data Exchange (ETDEWEB)

    Bellovary, Jillian M.; Low, Mordecai-Mark Mac; McKernan, Barry; Ford, K. E. Saavik [Department of Astrophysics, American Museum of Natural History, Central Park West at 79th Street, NY 10024 (United States)

    2016-03-10

    Accretion disks around supermassive black holes (SMBHs) in active galactic nuclei (AGNs) contain stars, stellar mass black holes, and other stellar remnants, which perturb the disk gas gravitationally. The resulting density perturbations exert torques on the embedded masses causing them to migrate through the disk in a manner analogous to planets in protoplanetary disks. We determine the strength and direction of these torques using an empirical analytic description dependent on local disk gradients, applied to two different analytic, steady-state disk models of SMBH accretion disks. We find that there are radii in such disks where the gas torque changes sign, trapping migrating objects. Our analysis shows that major migration traps generally occur where the disk surface density gradient changes sign from positive to negative, around 20–300R{sub g}, where R{sub g} = 2GM/c{sup 2} is the Schwarzschild radius. At these traps, massive objects in the AGN disk can accumulate, collide, scatter, and accrete. Intermediate mass black hole formation is likely in these disk locations, which may lead to preferential gap and cavity creation at these radii. Our model thus has significant implications for SMBH growth as well as gravitational wave source populations.

  9. Low Cost Heat Treatment Process for Production of Dual Microstructure Superalloy Disks

    Science.gov (United States)

    Gayda, John; Gabb, Tim; Kantzos, Pete; Furrer, David

    2003-01-01

    There are numerous incidents where operating conditions imposed on a component mandate different and distinct mechanical property requirements from location to location within the component. Examples include a crankshaft in an internal combustion engine, gears for an automotive transmission, and disks for a gas turbine engine. Gas turbine disks are often made from nickel-base superalloys, because these disks need to withstand the temperature and stresses involved in the gas turbine cycle. In the bore of the disk where the operating temperature is somewhat lower, the limiting material properties are often tensile and fatigue strength. In the rim of the disk, where the operating temperatures are higher than those of the bore, because of the proximity to the combustion gases, resistance to creep and crack growth are often the limiting properties.

  10. A DWARF TRANSITIONAL PROTOPLANETARY DISK AROUND XZ TAU B

    Energy Technology Data Exchange (ETDEWEB)

    Osorio, Mayra; Macías, Enrique; Anglada, Guillem; Gómez, José F. [Instituto de Astrofísica de Andalucía (CSIC), Glorieta de la Astronomía s/n, E-18008 Granada (Spain); Carrasco-González, Carlos; Galván-Madrid, Roberto; Zapata, Luis; Rodríguez, Luis F. [Instituto de Radioastronomía y Astrofísica UNAM, Apartado Postal 3-72 (Xangari), 58089 Morelia, Michoacán (Mexico); Calvet, Nuria [Department of Astronomy, University of Michigan, 825 Dennison Building, 500 Church Street, Ann Arbor, MI 48109 (United States); Nagel, Erick [Departamento de Astronomía, Universidad de Guanajuato, Guanajuato, Gto 36240 (Mexico); Torrelles, José M. [Institut de Ciències de l’Espai (CSIC)-Institut de Ciències del Cosmos (UB)/IEEC, Martí i Franquès 1, E-08028 Barcelona (Spain); Zhu, Zhaohuan, E-mail: osorio@iaa.es [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)

    2016-07-01

    We report the discovery of a dwarf protoplanetary disk around the star XZ Tau B that shows all the features of a classical transitional disk but on a much smaller scale. The disk has been imaged with the Atacama Large Millimeter/submillimeter Array (ALMA), revealing that its dust emission has a quite small radius of ∼3.4 au and presents a central cavity of ∼1.3 au in radius that we attribute to clearing by a compact system of orbiting (proto)planets. Given the very small radii involved, evolution is expected to be much faster in this disk (observable changes in a few months) than in classical disks (observable changes requiring decades) and easy to monitor with observations in the near future. From our modeling we estimate that the mass of the disk is large enough to form a compact planetary system.

  11. Full scale turbine-missile casing exit tests

    International Nuclear Information System (INIS)

    Yoshimura, H.R.; Schamaun, J.T.; Sliter, G.E.

    1979-01-01

    Two full-scale tests have simulated the impact of a fragment from a failed turbine disk upon the steel casing of a low-pressure steam turbine with the objective of providing data for making more realistic assessments of turbine missile effects for nuclear power plant designers. Data were obtained on both the energy-absorbing mechanisms of the impact process and the post-impact trajectory of the fragment. (orig.)

  12. Disk Storage Server

    CERN Multimedia

    This model was a disk storage server used in the Data Centre up until 2012. Each tray contains a hard disk drive (see the 5TB hard disk drive on the main disk display section - this actually fits into one of the trays). There are 16 trays in all per server. There are hundreds of these servers mounted on racks in the Data Centre, as can be seen.

  13. Understanding Floppy Disks.

    Science.gov (United States)

    Valentine, Pamela

    1980-01-01

    The author describes the floppy disk with an analogy to the phonograph record, and discusses the advantages, disadvantages, and capabilities of hard-sectored and soft-sectored floppy disks. She concludes that, at present, the floppy disk will continue to be the primary choice of personal computer manufacturers and their customers. (KC)

  14. Airfoil for a gas turbine

    Science.gov (United States)

    Liang, George [Palm City, FL

    2011-01-18

    An airfoil is provided for a gas turbine comprising an outer structure comprising a first wall, an inner structure comprising a second wall spaced relative to the first wall such that a cooling gap is defined between at least portions of the first and second walls, and seal structure provided within the cooling gap between the first and second walls for separating the cooling gap into first and second cooling fluid impingement gaps. An inner surface of the second wall may define an inner cavity. The inner structure may further comprise a separating member for separating the inner cavity of the inner structure into a cooling fluid supply cavity and a cooling fluid collector cavity. The second wall may comprise at least one first impingement passage, at least one second impingement passage, and at least one bleed passage.

  15. Singly-resonant sum frequency generation of visible light in a semiconductor disk laser

    DEFF Research Database (Denmark)

    Andersen, Martin Thalbitzer; Schlosser, P.J.; Hastie, J.E.

    2009-01-01

    In this paper a generic approach for visible light generation is presented. It is based on sum frequency generation between a semiconductor disk laser and a solid-state laser, where the frequency mixing is achieved within the cavity of the semiconductor disk laser using a singlepass of the solid......-state laser light. This exploits the good beam quality and high intra-cavity power present in the semiconductor disk laser to achieve high conversion efficiency. Combining sum frequency mixing and semiconductor disk lasers in this manner allows in principle for generation of any wavelength within the visible...

  16. Elastic limit angular speed of solid and annular disks under thermo ...

    African Journals Online (AJOL)

    Prof. Kashi Nath Sah

    disks, gas as well as steam turbine rotors, internal combustion engines, centrifugal compressors, and in aerospace industries. Mechanical design of disks entails the assessment of centrifugal as well as thermal stresses and they need to be designed for approximate uniform stress distributions. The analyses of stresses and ...

  17. HNC IN PROTOPLANETARY DISKS

    International Nuclear Information System (INIS)

    Graninger, Dawn; Öberg, Karin I.; Qi, Chunhua; Kastner, Joel

    2015-01-01

    The distributions and abundances of small organics in protoplanetary disks are potentially powerful probes of disk physics and chemistry. HNC is a common probe of dense interstellar regions and the target of this study. We use the Submillimeter Array (SMA) to observe HNC 3–2 toward the protoplanetary disks around the T Tauri star TW Hya and the Herbig Ae star HD 163296. HNC is detected toward both disks, constituting the first spatially resolved observations of HNC in disks. We also present SMA observations of HCN 3–2 and IRAM 30 m observations of HCN and HNC 1–0 toward HD 163296. The disk-averaged HNC/HCN emission ratio is 0.1–0.2 toward both disks. Toward TW Hya, the HNC emission is confined to a ring. The varying HNC abundance in the TW Hya disk demonstrates that HNC chemistry is strongly linked to the disk physical structure. In particular, the inner rim of the HNC ring can be explained by efficient destruction of HNC at elevated temperatures, similar to what is observed in the ISM. However, to realize the full potential of HNC as a disk tracer requires a combination of high SNR spatially resolved observations of HNC and HCN and disk-specific HNC chemical modeling

  18. HNC IN PROTOPLANETARY DISKS

    Energy Technology Data Exchange (ETDEWEB)

    Graninger, Dawn; Öberg, Karin I.; Qi, Chunhua [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Kastner, Joel, E-mail: dgraninger@cfa.harvard.edu [Center for Imaging Science, School of Physics and Astronomy, and Laboratory for Multiwavelength Astrophysics, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623 (United States)

    2015-07-01

    The distributions and abundances of small organics in protoplanetary disks are potentially powerful probes of disk physics and chemistry. HNC is a common probe of dense interstellar regions and the target of this study. We use the Submillimeter Array (SMA) to observe HNC 3–2 toward the protoplanetary disks around the T Tauri star TW Hya and the Herbig Ae star HD 163296. HNC is detected toward both disks, constituting the first spatially resolved observations of HNC in disks. We also present SMA observations of HCN 3–2 and IRAM 30 m observations of HCN and HNC 1–0 toward HD 163296. The disk-averaged HNC/HCN emission ratio is 0.1–0.2 toward both disks. Toward TW Hya, the HNC emission is confined to a ring. The varying HNC abundance in the TW Hya disk demonstrates that HNC chemistry is strongly linked to the disk physical structure. In particular, the inner rim of the HNC ring can be explained by efficient destruction of HNC at elevated temperatures, similar to what is observed in the ISM. However, to realize the full potential of HNC as a disk tracer requires a combination of high SNR spatially resolved observations of HNC and HCN and disk-specific HNC chemical modeling.

  19. Airfoil for a turbine of a gas turbine engine

    Science.gov (United States)

    Liang, George

    2010-12-21

    An airfoil for a turbine of a gas turbine engine is provided. The airfoil comprises a main body comprising a wall structure defining an inner cavity adapted to receive a cooling air. The wall structure includes a first diffusion region and at least one first metering opening extending from the inner cavity to the first diffusion region. The wall structure further comprises at least one cooling circuit comprising a second diffusion region and at least one second metering opening extending from the first diffusion region to the second diffusion region. The at least one cooling circuit may further comprise at least one third metering opening, at least one third diffusion region and a fourth diffusion region.

  20. Modeling collisions in circumstellar debris disks

    Science.gov (United States)

    Nesvold, Erika

    2015-10-01

    Observations of resolved debris disks show a spectacular variety of features and asymmetries, including inner cavities and gaps, inclined secondary disks or warps, and eccentric, sharp-edged rings. Embedded exoplanets could create many of these features via gravitational perturbations, which sculpt the disk directly and by generating planetesimal collisions. In this thesis, I present the Superparticle Model/Algorithm for Collisions in Kuiper belts and debris disks (SMACK), a new method for simultaneously modeling, in 3-D, the collisional and dynamical evolution of planetesimals in a debris disk with planets. SMACK can simulate azimuthal asymmetries and how these asymmetries evolve over time. I show that SMACK is stable to numerical viscosity and numerical heating over 107 yr, and that it can reproduce analytic models of disk evolution. As an example of the algorithm's capabilities, I use SMACK to model the evolution of a debris ring containing a planet on an eccentric orbit and demonstrate that differential precession creates a spiral structure as the ring evolves, but collisions subsequently break up the spiral, leaving a narrower eccentric ring. To demonstrate SMACK's utility in studying debris disk physics, I apply SMACK to simulate a planet on a circular orbit near a ring of planetesimals that are experiencing destructive collisions. Previous simulations of a planet opening a gap in a collisionless debris disk have found that the width of the gap scales as the planet mass to the 2/7th power (alpha = 2/7). I find that gap sizes in a collisional disk still obey a power law scaling with planet mass, but that the index alpha of the power law depends on the age of the system t relative to the collisional timescale t coll of the disk by alpha = 0.32(t/ tcoll)-0.04, with inferred planet masses up to five times smaller than those predicted by the classical gap law. The increased gap sizes likely stem from the interaction between collisions and the mean motion

  1. Secondary middle turbinate: case report

    Energy Technology Data Exchange (ETDEWEB)

    Aburjeli, Bruna de Oliveira Melim; Avila, Ana Flavia Assis de; Diniz, Renata Lopes Furletti Caldeira; Motta, Emilia Guerra Pinto Coelho; Ribeiro, Marcelo Almeida; Moreira, Wanderval, E-mail: bruninha86@hotmail.com [Radiology and Imaging Diagnosis, Hospital Mater Dei, Belo Horizonte, MG (Brazil)

    2012-11-15

    Secondary middle turbinate is an anatomical variant rarely observed in the nasal cavity, firstly described by Khanobthamchai et al. as a bone structure originating from the lateral nasal wall and covered by soft tissue. In most cases reported in the literature, this variant is bilateral, occurring without associated complications. In the present report, the authors describe the case of patient of their institution with such anatomical variation. (author)

  2. Secondary middle turbinate: case report

    International Nuclear Information System (INIS)

    Aburjeli, Bruna de Oliveira Melim; Avila, Ana Flavia Assis de; Diniz, Renata Lopes Furletti Caldeira; Motta, Emilia Guerra Pinto Coelho; Ribeiro, Marcelo Almeida; Moreira, Wanderval

    2012-01-01

    Secondary middle turbinate is an anatomical variant rarely observed in the nasal cavity, firstly described by Khanobthamchai et al. as a bone structure originating from the lateral nasal wall and covered by soft tissue. In most cases reported in the literature, this variant is bilateral, occurring without associated complications. In the present report, the authors describe the case of patient of their institution with such anatomical variation. (author)

  3. Power turbine ventilation system

    Science.gov (United States)

    Wakeman, Thomas G. (Inventor); Brown, Richard W. (Inventor)

    1991-01-01

    Air control mechanism within a power turbine section of a gas turbine engine. The power turbine section includes a rotor and at least one variable pitch propulsor blade. The propulsor blade is coupled to and extends radially outwardly of the rotor. A first annular fairing is rotatable with the propulsor blade and interposed between the propulsor blade and the rotor. A second fairing is located longitudinally adjacent to the first fairing. The first fairing and the second fairing are differentially rotatable. The air control mechanism includes a platform fixedly coupled to a radially inner end of the propulsor blade. The platform is generally positioned in a first opening and a first fairing. The platform and the first fairing define an outer space. In a first position corresponding with a first propulsor blade pitch, the platform is substantially conformal with the first fairing. In a second position corresponding with the second propulsor blade pitch, an edge portion of the platform is displaced radially outwardly from the first fairing. When the blades are in the second position and rotating about the engine axis, the displacement of the edge portion with respect to the first fairing allows air to flow from the outer space to the annular cavity.

  4. Gas turbines

    Energy Technology Data Exchange (ETDEWEB)

    Farahan, E.; Eudaly, J.P.

    1978-10-01

    This evaluation provides performance and cost data for commercially available simple- and regenerative-cycle gas turbines. Intercooled, reheat, and compound cycles are discussed from theoretical basis only, because actual units are not currently available, except on a special-order basis. Performance characteristics investigated include unit efficiency at full-load and off-design conditions, and at rated capacity. Costs are tabulated for both simple- and regenerative-cycle gas turbines. The output capacity of the gas turbines investigated ranges from 80 to 134,000 hp for simple units and from 12,000 to 50,000 hp for regenerative units.

  5. Exploring Disks Around Planets

    Science.gov (United States)

    Kohler, Susanna

    2017-07-01

    Giant planets are thought to form in circumstellar disks surrounding young stars, but material may also accrete into a smaller disk around the planet. Weve never detected one of these circumplanetary disks before but thanks to new simulations, we now have a better idea of what to look for.Image from previous work simulating a Jupiter-mass planet forming inside a circumstellar disk. The planet has its own circumplanetary disk of accreted material. [Frdric Masset]Elusive DisksIn the formation of giant planets, we think the final phase consists of accretion onto the planet from a disk that surrounds it. This circumplanetary disk is important to understand, since it both regulates the late gas accretion and forms the birthplace of future satellites of the planet.Weve yet to detect a circumplanetary disk thus far, because the resolution needed to spot one has been out of reach. Now, however, were entering an era where the disk and its kinematics may be observable with high-powered telescopes (like the Atacama Large Millimeter Array).To prepare for such observations, we need models that predict the basic characteristics of these disks like the mass, temperature, and kinematic properties. Now a researcher at the ETH Zrich Institute for Astronomy in Switzerland, Judit Szulgyi, has worked toward this goal.Simulating CoolingSzulgyi performs a series of 3D global radiative hydrodynamic simulations of 1, 3, 5, and 10 Jupiter-mass (MJ) giant planets and their surrounding circumplanetary disks, embedded within the larger circumstellar disk around the central star.Density (left column), temperature (center), and normalized angular momentum (right) for a 1 MJ planet over temperatures cooling from 10,000 K (top) to 1,000 K (bottom). At high temperatures, a spherical circumplanetary envelope surrounds the planet, but as the planet cools, the envelope transitions around 64,000 K to a flattened disk. [Szulgyi 2017]This work explores the effects of different planet temperatures and

  6. Pelton turbines

    CERN Document Server

    Zhang, Zhengji

    2016-01-01

    This book concerns the theoretical foundations of hydromechanics of Pelton turbines from the engineering viewpoint. For reference purposes, all relevant flow processes and hydraulic aspects in a Pelton turbine have been analyzed completely and systematically. The analyses especially include the quantification of all possible losses existing in the Pelton turbine and the indication of most available potential for further enhancing the system efficiency. As a guideline the book therefore supports further developments of Pelton turbines with regard to their hydraulic designs and optimizations. It is thus suitable for the development and design engineers as well as those working in the field of turbo machinery. Many laws described in the book can also be directly used to simplify aspects of computational fluid dynamics (CFD) or to develop new computational methods. The well-executed examples help better understand the related flow mechanics.

  7. The SEEDS Direct Imaging Survey for Planets and Scattered Dust Emission in Debris Disk Systems

    NARCIS (Netherlands)

    Janson, M.; et al., [Unknown; Thalmann, C.

    2013-01-01

    Debris disks around young main-sequence stars often have gaps and cavities which for a long time have been interpreted as possibly being caused by planets. In recent years, several giant planet discoveries have been made in systems hosting disks of precisely this nature, further implying that

  8. Cavity characterization for general use in linear electron accelerators

    International Nuclear Information System (INIS)

    Souza Neto, M.V. de.

    1985-01-01

    The main objective of this work is to is to develop measurement techniques for the characterization of microwave cavities used in linear electron accelerators. Methods are developed for the measurement of parameters that are essential to the design of an accelerator structure using conventional techniques of resonant cavities at low power. Disk-loaded cavities were designed and built, similar to those in most existing linear electron accelerators. As a result, the methods developed and the estimated accuracy were compared with those from other investigators. The results of this work are relevant for the design of cavities with the objective of developing linear electron accelerators. (author) [pt

  9. Limitations of the disk-and-washer structure

    International Nuclear Information System (INIS)

    Schriber, S.O.; Potter, J.M.

    1979-01-01

    A preliminary analysis of measurements on β = 0.6 and 1.0 disk-and-washer linac cavities has indicated some limitations on washer support methods; in particular, that the use of radial supports should be avoided until further testing is completed

  10. Magnetohydrodynamics of accretion disks

    International Nuclear Information System (INIS)

    Torkelsson, U.

    1994-04-01

    The thesis consists of an introduction and summary, and five research papers. The introduction and summary provides the background in accretion disk physics and magnetohydrodynamics. The research papers describe numerical studies of magnetohydrodynamical processes in accretion disks. Paper 1 is a one-dimensional study of the effect of magnetic buoyancy on a flux tube in an accretion disk. The stabilizing influence of an accretion disk corona on the flux tube is demonstrated. Paper 2-4 present numerical simulations of mean-field dynamos in accretion disks. Paper 11 verifies the correctness of the numerical code by comparing linear models to previous work by other groups. The results are also extended to somewhat modified disk models. A transition from an oscillatory mode of negative parity for thick disks to a steady mode of even parity for thin disks is found. Preliminary results for nonlinear dynamos at very high dynamo numbers are also presented. Paper 3 describes the bifurcation behaviour of the nonlinear dynamos. For positive dynamo numbers it is found that the initial steady solution is replaced by an oscillatory solution of odd parity. For negative dynamo numbers the solution becomes chaotic at sufficiently high dynamo numbers. Paper 4 continues the studies of nonlinear dynamos, and it is demonstrated that a chaotic solution appears even for positive dynamo numbers, but that it returns to a steady solution of mixed parity at very high dynamo numbers. Paper 5 describes a first attempt at simulating the small-scale turbulence of an accretion disk in three dimensions. There is only find cases of decaying turbulence, but this is rather due to limitations of the simulations than that turbulence is really absent in accretion disks

  11. PANCHROMATIC IMAGING OF A TRANSITIONAL DISK: THE DISK OF GM AUR IN OPTICAL AND FUV SCATTERED LIGHT

    Energy Technology Data Exchange (ETDEWEB)

    Hornbeck, J. B.; Williger, G. M.; Lauroesch, J. T. [Department of Physics and Astronomy, University of Louisville, Louisville, KY 40292 (United States); Swearingen, J. R.; Sitko, M. L.; Champney, E. H. [Department of Physics, University of Cincinnati, 400 Geology/Physics Building, P.O. Box 210011, Cincinnati, OH 45221-0377 (United States); Grady, C. A. [Eureka Scientific, 2452 Delmer Street, Suite 100, Oakland, CA 96402 (United States); Brown, A. [CASA, University of Colorado, Boulder, CO 80309-0593 (United States); Wisniewski, J. P. [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks Street, Norman, OK 73019 (United States); Perrin, M. D.; Schneider, G. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Apai, D. [Department of Astronomy and Steward Observatory, University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721 (United States); Brittain, S. [Department of Physics and Astronomy, Clemson University, 118 Kinard Laboratory, Clemson, SC 29634-0978 (United States); Brown, J. M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Hamaguchi, K. [Department of Physics, UMBC, Baltimore, MD 21250 (United States); Henning, Th. [Max-Planck-Institut Für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Lynch, D. K.; Russell, R. W. [The Aerospace Corporation, Los Angeles, CA 90009 (United States); Petre, R. [NASA’s Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Walter, F. M., E-mail: jeremy.hornbeck@louisville.edu, E-mail: gmwill06@louisville.edu, E-mail: carol.a.grady@nasa.gov [Department of Physics and Astronomy, Z = 3800, Stony Brook University, Stony Brook, NY 11794-3800 (United States); and others

    2016-10-01

    We have imaged GM Aurigae with the Hubble Space Telescope , detected its disk in scattered light at 1400 and 1650 Å, and compared these with observations at 3300 Å, 5550 Å, 1.1 μ m, and 1.6 μ m. The scattered light increases at shorter wavelengths. The radial surface brightness profile at 3300 Å shows no evidence of the 24 au radius cavity that has been previously observed in submillimeter observations. Comparison with dust grain opacity models indicates that the surface of the entire disk is populated with submicron grains. We have compiled a spectral energy distribution from 0.1 μ m to 1 mm and used it to constrain a model of the star + disk system that includes the submillimeter cavity using the Monte Carlo radiative transfer code by Barbara Whitney. The best-fit model image indicates that the cavity should be detectable in the F330W bandpass if the cavity has been cleared of both large and small dust grains, but we do not detect it. The lack of an observed cavity can be explained by the presence of submicron grains interior to the submillimeter cavity wall. We suggest one explanation for this that could be due to a planet of mass <9 M {sub J} interior to 24 au. A unique cylindrical structure is detected in the far-UV data from the Advanced Camera for Surveys/Solar Blind Channel. It is aligned along the system semiminor axis, but does not resemble an accretion-driven jet. The structure is limb brightened and extends 190 ± 35 au above the disk midplane. The inner radius of the limb brightening is 40 ± 10 au, just beyond the submillimeter cavity wall.

  12. Probing Protoplanetary Disks: From Birth to Planets

    Science.gov (United States)

    Cox, Erin Guilfoil

    2018-01-01

    49 pre main-sequence stellar systems and detected either gaps or cavities in ~6 of these sources. Combined, these results build upon how early protoplanetary disks can form around young protostars and thus how early planets can begin to form.

  13. Wind turbine

    Science.gov (United States)

    Cheney, Jr., Marvin C.

    1982-01-01

    A wind turbine of the type having an airfoil blade (15) mounted on a flexible beam (20) and a pitch governor (55) which selectively, torsionally twists the flexible beam in response to wind turbine speed thereby setting blade pitch, is provided with a limiter (85) which restricts unwanted pitch change at operating speeds due to torsional creep of the flexible beam. The limiter allows twisting of the beam by the governor under excessive wind velocity conditions to orient the blades in stall pitch positions, thereby preventing overspeed operation of the turbine. In the preferred embodiment, the pitch governor comprises a pendulum (65,70) which responds to changing rotor speed by pivotal movement, the limiter comprising a resilient member (90) which engages an end of the pendulum to restrict further movement thereof, and in turn restrict beam creep and unwanted blade pitch misadjustment.

  14. CN rings in full protoplanetary disks around young stars as probes of disk structure

    Science.gov (United States)

    Cazzoletti, P.; van Dishoeck, E. F.; Visser, R.; Facchini, S.; Bruderer, S.

    2018-01-01

    Aims: Bright ring-like structure emission of the CN molecule has been observed in protoplanetary disks. We investigate whether such structures are due to the morphology of the disk itself or if they are instead an intrinsic feature of CN emission. With the intention of using CN as a diagnostic, we also address to which physical and chemical parameters CN is most sensitive. Methods: A set of disk models were run for different stellar spectra, masses, and physical structures via the 2D thermochemical code DALI. An updated chemical network that accounts for the most relevant CN reactions was adopted. Results: Ring-shaped emission is found to be a common feature of all adopted models; the highest abundance is found in the upper outer regions of the disk, and the column density peaks at 30-100 AU for T Tauri stars with standard accretion rates. Higher mass disks generally show brighter CN. Higher UV fields, such as those appropriate for T Tauri stars with high accretion rates or for Herbig Ae stars or for higher disk flaring, generally result in brighter and larger rings. These trends are due to the main formation paths of CN, which all start with vibrationally excited H_2^* molecules, that are produced through far ultraviolet (FUV) pumping of H2. The model results compare well with observed disk-integrated CN fluxes and the observed location of the CN ring for the TW Hya disk. Conclusions: CN rings are produced naturally in protoplanetary disks and do not require a specific underlying disk structure such as a dust cavity or gap. The strong link between FUV flux and CN emission can provide critical information regarding the vertical structure of the disk and the distribution of dust grains which affects the UV penetration, and could help to break some degeneracies in the SED fitting. In contrast with C2H or c-C3H2, the CN flux is not very sensitive to carbon and oxygen depletion.

  15. Compressive residual stresses as a preventive measure against stress corrosion cracking on turbine components

    International Nuclear Information System (INIS)

    Berger, C.; Ewald, J.; Fischer, K.; Gruendler, O.; Potthast, E.; Stuecker, E.; Winzen, G.

    1987-01-01

    Disk type low pressure turbine rotors have been designed for a large variety of power plant applications. Developing disk type rotors required a concerted effort to design a shaft/disk shrink fit with a minimum of tensile stress concentrations in order to aim for the lowest possible susceptibility to corrosive attack, i.e. stress corrosion cracking. As a result of stresses, the regions of greatest concern are the shrink fit boundaries and the keyways of turbine disks. These stresses are caused by service loading, i.e. centrifugal and shrinkage stresses and by manufacturing procedure, i.e. residual stresses. The compressive residual stresses partly compensate the tensile service stresses so that an increase of compressive residual stresses decreases the whole stress state of the component. Special manufacturing procedures, e.g. accelerated cooling after tempering can induce compressive residual stresses up to about 400 MPa in the hub bore region of turbine disk

  16. Air riding seal with purge cavity

    Science.gov (United States)

    Sexton, Thomas D; Mills, Jacob A

    2017-08-15

    An air riding seal for a turbine in a gas turbine engine, where an annular piston is axial moveable within an annular piston chamber formed in a stator of the turbine and forms a seal with a surface on the rotor using pressurized air that forms a cushion in a pocket of the annular piston. A purge cavity is formed on the annular piston and is connected to a purge hole that extends through the annular piston to a lower pressure region around the annular piston or through the rotor to an opposite side. The annular piston is sealed also with inner and outer seals that can be a labyrinth seal to form an additional seal than the cushion of air in the pocket to prevent the face of the air riding seal from overheating.

  17. Analytical approach and scaling laws in the design of disk-loaded travelling wave accelerating structures

    International Nuclear Information System (INIS)

    Gao, J.

    1993-09-01

    Starting from a single resonant rf cavity, disk-loaded travelling (forward or backward) wave accelerating structures' properties are determined by rather simple analytical formulae. They include the coupling coefficient K in the dispersion relation, group velocity v g , shunt impedance R, wake potential W (longitudinal and transverse), the coupling coefficient β of the coupler cavity and the coupler cavity axis shift δ r which is introduced to compensate the asymmetry caused by the coupling aperture. (author) 12 refs., 18 figs

  18. Disk Defect Data

    Data.gov (United States)

    National Aeronautics and Space Administration — How Data Was Acquired: The data presented is from a physical simulator that simulated engine disks. Sample Rates and Parameter Description: All parameters are...

  19. Verbatim Floppy Disk

    CERN Multimedia

    1976-01-01

    Introduced under the name "Verbatim", Latin for "literally", these disks that sized more than 5¼ inches have become almost universal on dedicated word processing systems and personal computers. This format was replaced more slowly by the 3½-inch format, introduced for the first time in 1982. Compared to today, these large format disks stored very little data. In reality, they could only contain a few pages of text.

  20. Transitional Disks Associated with Intermediate-Mass Stars: Results of the SEEDS YSO Survey

    Science.gov (United States)

    Grady, C.; Fukagawa, M.; Maruta, Y.; Ohta, Y.; Wisniewski, J.; Hashimoto, J.; Okamoto, Y.; Momose, M.; Currie, T.; McElwain, M.; hide

    2014-01-01

    Protoplanetary disks are where planets form, grow, and migrate to produce the diversity of exoplanet systems we observe in mature systems. Disks where this process has advanced to the stage of gap opening, and in some cases central cavity formation, have been termed pre-transitional and transitional disks in the hope that they represent intermediate steps toward planetary system formation. Recent reviews have focussed on disks where the star is of solar or sub-solar mass. In contrast to the sub-millimeter where cleared central cavities predominate, at H-band some T Tauri star transitional disks resemble primordial disks in having no indication of clearing, some show a break in the radial surface brightness profile at the inner edge of the outer disk, while others have partially to fully cleared gaps or central cavities. Recently, the Meeus Group I Herbig stars, intermediate-mass PMS stars with IR spectral energy distributions often interpreted as flared disks, have been proposed to have transitional and pre-transitional disks similar to those associated with solar-mass PMS stars, based on thermal-IR imaging, and sub-millimeter interferometry. We have investigated their appearance in scattered light as part of the Strategic Exploration of Exoplanets and Disks with Subaru (SEEDS), obtaining H-band polarimetric imagery of 10 intermediate-mass stars with Meeus Group I disks. Augmented by other disks with imagery in the literature, the sample is now sufficiently large to explore how these disks are similar to and differ from T Tauri star disks. The disk morphologies seen in the Tauri disks are also found for the intermediate-mass star disks, but additional phenomena are found; a hallmark of these disks is remarkable individuality and diversity which does not simply correlate with disk mass or stellar properties, including age, including spiral arms in remnant envelopes, arms in the disk, asymmetrically and potentially variably shadowed outer disks, gaps, and one disk

  1. Mechanical and thermal stresses in a functionally graded rotating disk with variable thickness due to radially symmetry loads

    International Nuclear Information System (INIS)

    Bayat, Mehdi; Saleem, M.; Sahari, B.B.; Hamouda, A.M.S.; Mahdi, E.

    2009-01-01

    Rotating disks have many applications in the aerospace industry such as gas turbines and gears. These disks normally work under thermo mechanical loads. Minimizing the weight of such components can help reduce the overall payload in aerospace industry. For this purpose, a rotating functionally graded (FG) disk with variable thickness under a steady temperature field is considered in this paper. Thermo elastic solutions and the weight of the disk are related to the material grading index and the geometry of the disk. It is found that a disk with parabolic or hyperbolic convergent thickness profile has smaller stresses and displacements compared to a uniform thickness disk. Maximum radial stress due to centrifugal load in the solid disk with parabolic thickness profile may not be at the center unlike uniform thickness disk. Functionally graded disk with variable thickness has smaller stresses due to thermal load compared to those with uniform thickness. It is seen that for a given value of grading index, the FG disk having concave thickness profile is the lightest in weight whereas the FG disk with uniform thickness profile is the heaviest. Also for any given thickness profile, the weight of the FG disk lies in between the weights of the all-metal and the all-ceramic disks.

  2. Mass distributions in disk galaxies

    NARCIS (Netherlands)

    Martinsson, Thomas; Verheijen, Marc; Bershady, Matthew; Westfall, Kyle; Andersen, David; Swaters, Rob

    We present results on luminous and dark matter mass distributions in disk galaxies from the DiskMass Survey. As expected for normal disk galaxies, stars dominate the baryonic mass budget in the inner region of the disk; however, at about four optical scale lengths (hR ) the atomic gas starts to

  3. Dusty disks around young stars

    NARCIS (Netherlands)

    Verhoeff, A.

    2009-01-01

    Stars are formed through the collapse of giant molecular clouds. During this contraction the matter spins up and naturally forms a circumstellar disk. Once accretion comes to a halt, these disks are relatively stable. Some disks are known to last up to 10 Myrs. Most disks however, dissipate on

  4. Coatings for Oxidation and Hot Corrosion Protection of Disk Alloys

    Science.gov (United States)

    Nesbitt, Jim; Gabb, Tim; Draper, Sue; Miller, Bob; Locci, Ivan; Sudbrack, Chantal

    2017-01-01

    Increasing temperatures in aero gas turbines is resulting in oxidation and hot corrosion attack of turbine disks. Since disks are sensitive to low cycle fatigue (LCF), any environmental attack, and especially hot corrosion pitting, can potentially seriously degrade the life of the disk. Application of metallic coatings are one means of protecting disk alloys from this environmental attack. However, simply the presence of a metallic coating, even without environmental exposure, can degrade the LCF life of a disk alloy. Therefore, coatings must be designed which are not only resistant to oxidation and corrosion attack, but must not significantly degrade the LCF life of the alloy. Three different Ni-Cr coating compositions (29, 35.5, 45wt. Cr) were applied at two thicknesses by Plasma Enhanced Magnetron Sputtering (PEMS) to two similar Ni-based disk alloys. One coating also received a thin ZrO2 overcoat. The coated samples were also given a short oxidation exposure in a low PO2 environment to encourage chromia scale formation. Without further environmental exposure, the LCF life of the coated samples, evaluated at 760C, was less than that of uncoated samples. Hence, application of the coating alone degraded the LCF life of the disk alloy. Since shot peening is commonly employed to improve LCF life, the effect of shot peening the coated and uncoated surface was also evaluated. For all cases, shot peening improved the LCF life of the coated samples. Coated and uncoated samples were shot peened and given environmental exposures consisting of 500 hrs of oxidation followed by 50 hrs of hot corrosion, both at 760C). The high-Cr coating showed the best LCF life after the environmental exposures. Results of the LCF testing and post-test characterization of the various coatings will be presented and future research directions discussed.

  5. 2TB hard disk drive

    CERN Multimedia

    This particular object was used up until 2012 in the Data Centre. It slots into one of the Disk Server trays. Hard disks were invented in the 1950s. They started as large disks up to 20 inches in diameter holding just a few megabytes (link is external). They were originally called "fixed disks" or "Winchesters" (a code name used for a popular IBM product). They later became known as "hard disks" to distinguish them from "floppy disks (link is external)." Hard disks have a hard platter that holds the magnetic medium, as opposed to the flexible plastic film found in tapes and floppies.

  6. Segmented trapped vortex cavity

    Science.gov (United States)

    Grammel, Jr., Leonard Paul (Inventor); Pennekamp, David Lance (Inventor); Winslow, Jr., Ralph Henry (Inventor)

    2010-01-01

    An annular trapped vortex cavity assembly segment comprising includes a cavity forward wall, a cavity aft wall, and a cavity radially outer wall there between defining a cavity segment therein. A cavity opening extends between the forward and aft walls at a radially inner end of the assembly segment. Radially spaced apart pluralities of air injection first and second holes extend through the forward and aft walls respectively. The segment may include first and second expansion joint features at distal first and second ends respectively of the segment. The segment may include a forward subcomponent including the cavity forward wall attached to an aft subcomponent including the cavity aft wall. The forward and aft subcomponents include forward and aft portions of the cavity radially outer wall respectively. A ring of the segments may be circumferentially disposed about an axis to form an annular segmented vortex cavity assembly.

  7. Study of cavitation in hydro turbines. A review

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Pardeep; Saini, R.P. [Alternate Hydro Energy Centre, Indian Institute of Technology, Roorkee 247667 (India)

    2010-01-15

    Reaction turbines basically Francis turbines and propeller/Kaplan turbines are suitable for medium and low head hydropower sites. The management of the small hydropower plants is an important factor, for achieving higher efficiency of hydro turbines with time. Turbines show declined performance after few years of operation, as they get severely damaged due to various reasons. One of the important reasons is erosive wear of the turbines due to cavitation. Reaction turbines, however are more prone to cavitation especially Francis turbines where a zone in the operating range is seriously affected by cavitation and considered as forbidden zone. Cavitation is a phenomenon which manifests itself in the pitting of the metallic surfaces of turbine parts because of the formation of cavities. In the present paper, studies undertaken in this field by several investigators have been discussed extensively. Based on literature survey various aspects related to cavitation in hydro turbines, different causes for the declined performance and efficiency of the hydro turbines and suitable remedial measures suggested by various investigators have been discussed. (author)

  8. Debris Disks: Probing Planet Formation

    OpenAIRE

    Wyatt, Mark C.

    2018-01-01

    Debris disks are the dust disks found around ~20% of nearby main sequence stars in far-IR surveys. They can be considered as descendants of protoplanetary disks or components of planetary systems, providing valuable information on circumstellar disk evolution and the outcome of planet formation. The debris disk population can be explained by the steady collisional erosion of planetesimal belts; population models constrain where (10-100au) and in what quantity (>1Mearth) planetesimals (>10km i...

  9. Fast, Capacious Disk Memory Device

    Science.gov (United States)

    Muller, Ronald M.

    1990-01-01

    Device for recording digital data on, and playing back data from, memory disks has high recording or playback rate and utilizes available recording area more fully. Two disks, each with own reading/writing head, used to record data at same time. Head on disk A operates on one of tracks numbered from outside in; head on disk B operates on track of same number in sequence from inside out. Underlying concept of device applicable to magnetic or optical disks.

  10. Source to Accretion Disk Tilt

    OpenAIRE

    Montgomery, M. M.; Martin, E. L.

    2010-01-01

    Many different system types retrogradely precess, and retrograde precession could be from a tidal torque by the secondary on a misaligned accretion disk. However, a source to cause and maintain disk tilt is unknown. In this work, we show that accretion disks can tilt due to a force called lift. Lift results from differing gas stream supersonic speeds over and under an accretion disk. Because lift acts at the disk's center of pressure, a torque is applied around a rotation axis passing through...

  11. Hydraulic turbines and auxiliary equipment

    Energy Technology Data Exchange (ETDEWEB)

    Luo Gaorong [Organization of the United Nations, Beijing (China). International Centre of Small Hydroelectric Power Plants

    1995-07-01

    This document presents a general overview on hydraulic turbines and auxiliary equipment, emphasizing the turbine classification, in accordance with the different types of turbines, standard turbine series in China, turbine selection based on the basic data required for the preliminary design, general hill model curves, chart of turbine series and the arrangement of application for hydraulic turbines, hydraulic turbine testing, and speed regulating device.

  12. PLANETESIMAL DISK MICROLENSING

    International Nuclear Information System (INIS)

    Heng, Kevin; Keeton, Charles R.

    2009-01-01

    Motivated by debris disk studies, we investigate the gravitational microlensing of background starlight by a planetesimal disk around a foreground star. We use dynamical survival models to construct a plausible example of a planetesimal disk and study its microlensing properties using established ideas of microlensing by small bodies. When a solar-type source star passes behind a planetesimal disk, the microlensing light curve may exhibit short-term, low-amplitude residuals caused by planetesimals several orders of magnitude below Earth mass. The minimum planetesimal mass probed depends on the photometric sensitivity and the size of the source star, and is lower when the planetesimal lens is located closer to us. Planetesimal lenses may be found more nearby than stellar lenses because the steepness of the planetesimal mass distribution changes how the microlensing signal depends on the lens/source distance ratio. Microlensing searches for planetesimals require essentially continuous monitoring programs that are already feasible and can potentially set constraints on models of debris disks, the progeny of the supposed extrasolar analogues of Kuiper Belts.

  13. Herniated lumbar intervertebral disk

    International Nuclear Information System (INIS)

    Hochhauser, L.; Cacayorin, E.D.; Karcnik, T.J.; McGowan, D.P.; Clark, K.G.; Storrs, D.; Kieffer, S.A.

    1988-01-01

    From a series of 25 patients with low-back pain and sciatica who subsequently underwent surgical exploration, 24 lumbar herniated disks and one asymmetrically bulging disk were correctly diagnosed with use of a 0.5-T MR imaging unit. The radiologic findings on saggital images included a polypoid protrusion beyond the posterior margin of the vertebral bodies more clearly displayed with T1-weighted than with T-2 weighted sequences and a focal extension into the extradural space on axial views. In most, the signal intensity of HNP was isointense to the disk of origin. The study suggests that MR imaging is currently capable of accurately predicting an HNP. The diagnosis is based primarily on morphologic characteristics rather than signal intensity alterations

  14. Relativistic, accreting disks

    International Nuclear Information System (INIS)

    Abramowicz, M.A; Jaroszynski, M.; Sikora, M.

    1978-01-01

    An analytic theory of the hydrodynamical structure of accreting disks (without self-gravitation but with pressure) orbiting around and axially symmetric, stationary, compact body (e.g. black hole) is presented. The inner edge of the marginally stable accreting disk (i.e. disk with constant angular momentum density) has a sharp cusp located on the equatorial plane between rsub(ms) and rsub(mb). The existence of the cusp is also typical for any angular momentum distribution. The physical importance of the cusp follows from the close analogy with the case of a close binary system (L 1 Lagrange point on the Roche lobe). The existence of the cusp is thus a crucial phenomenon in such problems as boundary condition for the viscous stresses, accretion rate etc. (orig.) [de

  15. Relativistic, accreting disks

    Energy Technology Data Exchange (ETDEWEB)

    Abramowicz, M A; Jaroszynski, M; Sikora, M [Polska Akademia Nauk, Warsaw

    1978-02-01

    An analytic theory of the hydrodynamical structure of accreting disks (without self-gravitation but with pressure) orbiting around an axially symmetric, stationary, compact body (e.g. black hole) is presented. The inner edge of the marginally stable accreting disk (i.e. disk with constant angular momentum density) has a sharp cusp located on the equatorial plane between r/sub ms/ and r/sub mb/. The existence of the cusp is also typical for any angular momentum distribution. The physical importance of the cusp follows from the close analogy with the case of a close binary system (L/sub 1/ Lagrange point on the Roche lobe). The existence of the cusp is thus a crucial phenomenon in such problems as boundary condition for the viscous stresses, accretion rate, etc.

  16. Chemistry in protoplanetary disks

    Science.gov (United States)

    Semenov, D. A.

    2012-01-01

    In this lecture I discuss recent progress in the understanding of the chemical evolution of protoplanetary disks that resemble our Solar system during the first ten million years. At the verge of planet formation, strong variations of temperature, density, and radiation intensities in these disks lead to a layered chemical structure. In hot, dilute and heavily irradiated atmosphere only simple radicals, atoms, and atomic ions can survive, formed and destroyed by gas-phase processes. Beneath the atmosphere a partly UV-shielded, warm molecular layer is located, where high-energy radiation drives rich chemistry, both in the gas phase and on dust surfaces. In a cold, dense, dark disk midplane many molecules are frozen out, forming thick icy mantles where surface chemistry is active and where complex (organic) species are synthesized.

  17. Dual Microstructure Heat Treatment of a Nickel-Base Disk Alloy Assessed

    Science.gov (United States)

    Gayda, John

    2002-01-01

    Gas turbine engines for future subsonic aircraft will require nickel-base disk alloys that can be used at temperatures in excess of 1300 F. Smaller turbine engines, with higher rotational speeds, also require disk alloys with high strength. To address these challenges, NASA funded a series of disk programs in the 1990's. Under these initiatives, Honeywell and Allison focused their attention on Alloy 10, a high-strength, nickel-base disk alloy developed by Honeywell for application in the small turbine engines used in regional jet aircraft. Since tensile, creep, and fatigue properties are strongly influenced by alloy grain size, the effect of heat treatment on grain size and the attendant properties were studied in detail. It was observed that a fine grain microstructure offered the best tensile and fatigue properties, whereas a coarse grain microstructure offered the best creep resistance at high temperatures. Therefore, a disk with a dual microstructure, consisting of a fine-grained bore and a coarse-grained rim, should have a high potential for optimal performance. Under NASA's Ultra-Safe Propulsion Project and Ultra-Efficient Engine Technology (UEET) Program, a disk program was initiated at the NASA Glenn Research Center to assess the feasibility of using Alloy 10 to produce a dual-microstructure disk. The objectives of this program were twofold. First, existing dual-microstructure heat treatment (DMHT) technology would be applied and refined as necessary for Alloy 10 to yield the desired grain structure in full-scale forgings appropriate for use in regional gas turbine engines. Second, key mechanical properties from the bore and rim of a DMHT Alloy 10 disk would be measured and compared with conventional heat treatments to assess the benefits of DMHT technology. At Wyman Gordon and Honeywell, an active-cooling DMHT process was used to convert four full-scale Alloy 10 disks to a dual-grain microstructure. The resulting microstructures are illustrated in the

  18. ACCRETION KINEMATICS THROUGH THE WARPED TRANSITION DISK IN HD 142527 FROM RESOLVED CO(6–5) OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Casassus, S.; Marino, S.; Pérez, S.; Plas, G. van der; Christiaens, V.; Montesinos, Matías [Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago (Chile); Roman, P.; Dunhill, A.; Cuadra, J.; Cieza, L.; Moral, Victor [Millennium Nucleus “Protoplanetary Disks,” Chile (Chile); Armitage, P. J. [JILA, University of Colorado and NIST, UCB 440, Boulder, CO 80309 (United States); Wootten, A., E-mail: scasassus@u.uchile.cl [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475 (United States)

    2015-10-01

    The finding of residual gas in the large central cavity of the HD 142527 disk motivates questions regarding the origin of its non-Keplerian kinematics and possible connections with planet formation. We aim to understand the physical structure that underlies the intra-cavity gaseous flows, guided by new molecular-line data in CO(6–5) with unprecedented angular resolutions. Given the warped structure inferred from the identification of scattered-light shadows cast on the outer disk, the kinematics are consistent, to first order, with axisymmetric accretion onto the inner disk occurring at all azimuths. A steady-state accretion profile, fixed at the stellar accretion rate, explains the depth of the cavity as traced in CO isotopologues. The abrupt warp and evidence for near free-fall radial flows in HD 142527 resemble theoretical models for disk tearing, which could be driven by the reported low-mass companion, whose orbit may be contained in the plane of the inner disk. The companion’s high inclination with respect to the massive outer disk could drive Kozai oscillations over long timescales; high-eccentricity periods may perhaps account for the large cavity. While shadowing by the tilted disk could imprint an azimuthal modulation in the molecular-line maps, further observations are required to ascertain the significance of azimuthal structure in the density field inside the cavity of HD 142527.

  19. N18, powder metallurgy superalloy for disks: Development and applications

    Energy Technology Data Exchange (ETDEWEB)

    Guedou, J.Y.; Lautridou, J.C.; Honnorat, Y. (SNECMA, Evry (France). Materials and Processes Dept.)

    1993-08-01

    The preliminary industrial development of a powder metallurgy (PM) superalloy, designated N18, for disk applications has been completed. This alloy exhibits good overall mechanical properties after appropriate processing of the material. These properties have been measured on both isothermally forged and extruded billets, as well as on specimens cut from actual parts. The temperature capability of the alloy is about 700 C for long-term applications and approximately 750 C for short-term use because of microstructural instability. Further improvements in creep and crack propagation properties, without significant reduction in tensile strength, are possible through appropriate thermomechanical processing, which results in a large controlled grain size. Spin pit tests on subscale disks have confirmed that the N18 alloy has a higher resistance than PM Astrology and is therefore an excellent alloy for modern turbine disk applications.

  20. Phase Stability of a Powder Metallurgy Disk Superalloy

    Science.gov (United States)

    Gabb, Timothy P.; Gayda, John; Kantzos, P.; Telesman, Jack; Gang, Anita

    2006-01-01

    Advanced powder metallurgy superalloy disks in aerospace turbine engines now entering service can be exposed to temperatures approaching 700 C, higher than those previously encountered. They also have higher levels of refractory elements, which can increase mechanical properties at these temperatures but can also encourage phase instabilities during service. Microstructural changes including precipitation of topological close pack phase precipitation and coarsening of existing gamma' precipitates can be slow at these temperatures, yet potentially significant for anticipated disk service times exceeding 1,000 h. The ability to quantify and predict such potential phase instabilities and degradation of capabilities is needed to insure structural integrity and air worthiness of propulsion systems over the full life cycle. A prototypical advanced disk superalloy was subjected to high temperature exposures, and then evaluated. Microstructural changes and corresponding changes in mechanical properties were quantified. The results will be compared to predictions of microstructure modeling software.

  1. Turbine stage model

    International Nuclear Information System (INIS)

    Kazantsev, A.A.

    2009-01-01

    A model of turbine stage for calculations of NPP turbine department dynamics in real time was developed. The simulation results were compared with manufacturer calculations for NPP low-speed and fast turbines. The comparison results have shown that the model is valid for real time simulation of all modes of turbines operation. The model allows calculating turbine stage parameters with 1% accuracy. It was shown that the developed turbine stage model meets the accuracy requirements if the data of turbine blades setting angles for all turbine stages are available [ru

  2. Circumstellar and circumplanetary disks

    Science.gov (United States)

    Chiang, Eugene

    2000-11-01

    This thesis studies disks in three astrophysical contexts: (1)protoplanetary disks; (2)the Edgeworth-Kuiper Belt; and (3)planetary rings. We derive hydrostatic, radiative equilibrium models of passive protoplanetary disks surrounding T Tauri and Herbig Ae/Be stars. Each disk is encased by an optically thin layer of superheated dust grains. This layer is responsible for up to ~70% of the disk luminosity at wavelengths between ~5 and 60 μm. The heated disk flares and absorbs more stellar radiation at a given stellocentric distance than a flat disk would. Spectral energy distributions are computed and found to compare favorably with the observed flattish infrared excesses of several young stellar objects. Spectral features from dust grains in the superheated layer appear in emission if the disk is viewed nearly face-on. We present the results of a pencil-beam survey of the Kuiper Belt using the Keck 10-m telescope. Two new objects are discovered. Data from all surveys are pooled to construct the luminosity function from mR = 20 to 27. The cumulative number of objects per square degree, Σ(surface area but the largest bodies contain most of the mass. To order-of-magnitude, 0.2 M⊕ and 1 × 1010 comet progenitors lie between 30 and 50 AU. The classical Kuiper Belt appears truncated at a distance of 50 AU. We propose that rigid precession of narrow eccentric planetary rings surrounding Uranus and Saturn is maintained by a balance of forces due to ring self- gravity, planetary oblateness, and interparticle collisions. Collisional impulses play an especially dramatic role near ring edges. Pressure-induced accelerations are maximal near edges because there (1)velocity dispersions are enhanced by resonant satellite perturbations, and (2)the surface density declines steeply. Remarkably, collisional forces felt by material in the last ~100 m of a ~10 km wide ring can increase equilibrium masses up to a factor of ~100. New ring surface densities are derived which accord with

  3. Flow visualization system for wind turbines without blades applied to micro reactors

    International Nuclear Information System (INIS)

    Santos, G.S.B.; Guimarães, L.N.F.; Placco, G.M.

    2017-01-01

    Flow visualization systems is a tool used in science and industry for characterization of projects that operate with drainage. This work presents the design and construction of a flow visualization system for passive turbines used in advanced fast micro reactors. In the system were generated images where it is possible to see the supersonic and transonic flow through the turbine disks. A test bench was assembled to generate images of the interior of the turbine where the flow is supersonic, allowing the study of the behavior of the boundary layer between disks. It is necessary to characterize the boundary layer of this type of turbine because its operation occurs in the transfer of kinetic energy between the fluid and the disks. The images generated, as well as their analyzes are presented as a result of this work

  4. Modeling Protoplanetary Disks

    Science.gov (United States)

    Holman, Megan; Tubbs, Drake; Keller, L. D.

    2018-01-01

    Using spectra models with known parameters and comparing them to spectra gathered from real systems is often the only ways to find out what is going on in those real systems. This project uses the modeling programs of RADMC-3D to generate model spectra for systems containing protoplanetary disks. The parameters can be changed to simulate protoplanetary disks in different stages of planet formation, with different sized gaps in different areas of the disks, as well as protoplanetary disks that contain different types of dust. We are working on producing a grid of models that all have different variations in the parameters in order to generate a miniature database to use for comparisons to gathered spectra. The spectra produced from these simulations will be compared to spectra that have been gathered from systems in the Small Magellanic cloud in order to find out the contents and stage of development of that system. This allows us to see if and how planets are forming in the Small Magellanic cloud, a region which has much less metallicity than our own galaxy. The data we gather from comparisons between the model spectra and the spectra of systems in the Small Magellanic Cloud can then be applied to how planets may have formed in the early universe.

  5. The Disk Mass Project

    NARCIS (Netherlands)

    Verheijen, Marc A. W.; Bershady, Matthew A.; Swaters, Rob A.; Andersen, David R.; Westfall, Kyle B.; de Jong, Roelof Sybe

    2007-01-01

    Little is known about the content and distribution of dark matter in spiral galaxies. To break the degeneracy in galaxy rotation curve decompositions, which allows a wide range of dark matter halo density profiles, an independent measure of the mass surface density of stellar disks is needed. Here,

  6. A CFD code comparison of wind turbine wakes

    DEFF Research Database (Denmark)

    Laan, van der, Paul Maarten; Storey, R. C.; Sørensen, Niels N.

    2014-01-01

    A comparison is made between the EllipSys3D and SnS CFD codes. Both codes are used to perform Large-Eddy Simulations (LES) of single wind turbine wakes, using the actuator disk method. The comparison shows that both LES models predict similar velocity deficits and stream-wise Reynolds-stresses fo...

  7. Use of magnetic compression to support turbine engine rotors

    Science.gov (United States)

    Pomfret, Chris J.

    1994-01-01

    Ever since the advent of gas turbine engines, their rotating disks have been designed with sufficient size and weight to withstand the centrifugal forces generated when the engine is operating. Unfortunately, this requirement has always been a life and performance limiting feature of gas turbine engines and, as manufacturers strive to meet operator demands for more performance without increasing weight, the need for innovative technology has become more important. This has prompted engineers to consider a fundamental and radical breakaway from the traditional design of turbine and compressor disks which have been in use since the first jet engine was flown 50 years ago. Magnetic compression aims to counteract, by direct opposition rather than restraint, the centrifugal forces generated within the engine. A magnetic coupling is created between a rotating disk and a stationary superconducting coil to create a massive inwardly-directed magnetic force. With the centrifugal forces opposed by an equal and opposite magnetic force, the large heavy disks could be dispensed with and replaced with a torque tube to hold the blades. The proof of this concept has been demonstrated and the thermal management of such a system studied in detail; this aspect, especially in the hot end of a gas turbine engine, remains a stiff but not impossible challenge. The potential payoffs in both military and commercial aviation and in the power generation industry are sufficient to warrant further serious studies for its application and optimization.

  8. Accreting planets as dust dams in 'transition' disks

    International Nuclear Information System (INIS)

    Owen, James E.

    2014-01-01

    We investigate under what circumstances an embedded planet in a protoplanetary disk may sculpt the dust distribution such that it observationally presents as a 'transition' disk. We concern ourselves with 'transition' disks that have large holes (≳ 10 AU) and high accretion rates (∼10 –9 -10 –8 M ☉ yr –1 ), particularly, those disks which photoevaporative models struggle to explain. Adopting the observed accretion rates in 'transition' disks, we find that the accretion luminosity from the forming planet is significant, and can dominate over the stellar luminosity at the gap edge. This planetary accretion luminosity can apply a significant radiation pressure to small (s ≲ 1 μm) dust particles provided they are suitably decoupled from the gas. Secular evolution calculations that account for the evolution of the gas and dust components in a disk with an embedded, accreting planet, show that only with the addition of the radiation pressure can we explain the full observed characteristics of a 'transition' disk (NIR dip in the spectral energy distribution (SED), millimeter cavity, and high accretion rate). At suitably high planet masses (≳ 3-4 M J ), radiation pressure from the accreting planet is able to hold back the small dust particles, producing a heavily dust-depleted inner disk that is optically thin to infrared radiation. The planet-disk system will present as a 'transition' disk with a dip in the SED only when the planet mass and planetary accretion rate are high enough. At other times, it will present as a disk with a primordial SED, but with a cavity in the millimeter, as observed in a handful of protoplanetary disks.

  9. Improved reactor cavity

    International Nuclear Information System (INIS)

    Katz, L.R.; Demarchais, W.E.

    1984-01-01

    A reactor pressure vessel disposed in a cavity has coolant inlet or outlet pipes extending through passages in the cavity walls and welded to pressure nozzles. The cavity wall has means for directing fluid away from a break at a weld away from the pressure vessel, and means for inhibiting flow of fluid toward the vessel. (author)

  10. Planetesimal Formation by the Streaming Instability in a Photoevaporating Disk

    Energy Technology Data Exchange (ETDEWEB)

    Carrera, Daniel; Johansen, Anders; Davies, Melvyn B. [Lund Observatory, Dept. of Astronomy and Theoretical Physics, Lund University, Box 43, SE-221 00 Lund (Sweden); Gorti, Uma [NASA Ames Research Center, Moffett Field, CA (United States)

    2017-04-10

    Recent years have seen growing interest in the streaming instability as a candidate mechanism to produce planetesimals. However, these investigations have been limited to small-scale simulations. We now present the results of a global protoplanetary disk evolution model that incorporates planetesimal formation by the streaming instability, along with viscous accretion, photoevaporation by EUV, FUV, and X-ray photons, dust evolution, the water ice line, and stratified turbulence. Our simulations produce massive (60–130 M {sub ⊕}) planetesimal belts beyond 100 au and up to ∼20 M {sub ⊕} of planetesimals in the middle regions (3–100 au). Our most comprehensive model forms 8 M {sub ⊕} of planetesimals inside 3 au, where they can give rise to terrestrial planets. The planetesimal mass formed in the inner disk depends critically on the timing of the formation of an inner cavity in the disk by high-energy photons. Our results show that the combination of photoevaporation and the streaming instability are efficient at converting the solid component of protoplanetary disks into planetesimals. Our model, however, does not form enough early planetesimals in the inner and middle regions of the disk to give rise to giant planets and super-Earths with gaseous envelopes. Additional processes such as particle pileups and mass loss driven by MHD winds may be needed to drive the formation of early planetesimal generations in the planet-forming regions of protoplanetary disks.

  11. Yield surface investigation of alloys during model disk spin tests

    Directory of Open Access Journals (Sweden)

    E. P. Kuzmin

    2014-01-01

    Full Text Available Gas-turbine engines operate under heavy subsequently static loading conditions. Disks of gas-turbine engine are high loaded parts of irregular shape having intensive stress concentrators wherein a 3D stress strain state occurs. The loss of load-carrying capability or burst of disk can lead to severe accident or disaster. Therefore, development of methods to assess deformations and to predict burst is one of the most important problems.Strength assessment approaches are used at all levels of engine creation. In recent years due to actively developing numerical method, particularly FEA, it became possible to investigate load-carrying capability of irregular shape disks, to use 3D computing schemes including flow theory and different options of force and deformation failure criteria. In spite of a wide progress and practical use of strength assessment approaches, there is a lack of detailed research data on yield surface of disk alloys. The main purpose of this work is to validate the use of basis hypothesis of flow theory and investigate the yield surface of disk alloys during the disks spin test.The results of quasi-static numerical simulation of spin tests of model disk made from high-temperature forged alloy are presented. To determine stress-strain state of disk during loading finite element analysis is used. Simulation of elastic-plastic strain fields was carried out using incremental theory of plasticity with isotropic hardening. Hardening function was taken from the results of specimens tensile test. Specimens were cut from a sinkhead of model disk. The paper investigates the model sensitivity affected by V.Mises and Tresca yield criteria as well as the Hosford model. To identify the material model parameters the eddy current sensors were used in the experimental approach to measure rim radial displacements during the load-unload of spin test. The results of calculation made using different material models were compared with the

  12. Tests of spinning turbine fragment impact on casing models

    International Nuclear Information System (INIS)

    Wilbeck, J.S.

    1984-01-01

    Ten 1/11-scale model turbine missile impact tests were conducted at a Naval spin chamber test facility to assess turbine missile effects in nuclear plant design. The objective of the tests was to determine the effects of missile spin, blade crush, and target edge conditions on the impact of turbine disk fragments on the steel casing. The results were intended for use in making realistic estimates for the initial conditions of fragments that might escape the casing in the event of a disk burst in a nuclear plant. The burst of a modified gas turbine rotor in a high-speed spin chamber provided three missiles with the proper rotational and translational velocities of actual steam turbine fragments. Tests of bladed, spinning missiles were compared with previous tests of unbladed, nonspinning missiles. The total residual energy of the spinning missiles, as observed from high-speed photographs of disk burst, was the same as that of the nonspinning missiles launched in a piercing orientation. Tests with bladed missiles showed that for equal burst speeds, the residual energy of bladed missiles is less than that of unbladed missiles. Impacts of missiles near the edge of targets resulted in residual missile velocities greater than for central impact. (orig.)

  13. Identifying Likely Disk-hosting M dwarfs with Disk Detective

    Science.gov (United States)

    Silverberg, Steven; Wisniewski, John; Kuchner, Marc J.; Disk Detective Collaboration

    2018-01-01

    M dwarfs are critical targets for exoplanet searches. Debris disks often provide key information as to the formation and evolution of planetary systems around higher-mass stars, alongside the planet themselves. However, less than 300 M dwarf debris disks are known, despite M dwarfs making up 70% of the local neighborhood. The Disk Detective citizen science project has identified over 6000 new potential disk host stars from the AllWISE catalog over the past three years. Here, we present preliminary results of our search for new disk-hosting M dwarfs in the survey. Based on near-infrared color cuts and fitting stellar models to photometry, we have identified over 500 potential new M dwarf disk hosts, nearly doubling the known number of such systems. In this talk, we present our methodology, and outline our ongoing work to confirm systems as M dwarf disks.

  14. Turbine main engines

    CERN Document Server

    Main, John B; Herbert, C W; Bennett, A J S

    1965-01-01

    Turbine Main Engines deals with the principle of operation of turbine main engines. Topics covered include practical considerations that affect turbine design and efficiency; steam turbine rotors, blades, nozzles, and diaphragms; lubricating oil systems; and gas turbines for use with nuclear reactors. Gas turbines for naval boost propulsion, merchant ship propulsion, and naval main propulsion are also considered. This book is divided into three parts and begins with an overview of the basic mode of operation of the steam turbine engine and how it converts the pressure energy of the ingoing ste

  15. A mathematical model of bird collisions with wind turbine rotors

    International Nuclear Information System (INIS)

    Tucker, V.A.

    1996-01-01

    When a bird flies through the disk swept out by the blades of a wind turbine rotor, the probability of collision depends on the motions and dimensions of the bird and the blades. The collision model in this paper predicts the probability for birds that glide upwind, downwind, an across the wind past simple one-dimensional blades represented by straight lines, and upwind and downwind past more realistic three-dimensional blades with chord and twist. Probabilities vary over the surface of the disk, and in most cases, the tip of the blade is less likely to collide with a bird than parts of the blade nearer the hub. The mean probability may be found by integration over the disk area. The collision model identifies the rotor characteristics that could be altered to make turbines safer for birds

  16. Scattering properties of vein induced localized surface plasmon resonances on a gold disk

    KAUST Repository

    Amin, Muhammad

    2011-12-01

    It is demonstrated via simulations that a gold nano-disk with a non-concentric cavity supports localized surface plasmon resonances over a frequency band that includes the visible and the near-infrared parts of the spectrum. The charge distribution on the disk indicates that the two distinct peaks in the scattering cross section are due to the (hybridized) higher-order plasmon modes; plasmon hybridization that involves the dipole modes of the disk and the cavity enforces the "coupling" of the plane-wave excitation to the originally-dark higher-order modes. It is further demonstrated that the resonance frequencies can be tuned by varying the radius of the embedded non-concentric cavity. The near-field enhancement observed at these two tunable resonance frequencies suggests that the proposed structure can be used as a substrate in surface enhanced spectroscopy applications. © 2011 IEEE.

  17. Turbine system and adapter

    Science.gov (United States)

    Hogberg, Nicholas Alvin; Garcia-Crespo, Andres Jose

    2017-05-30

    A turbine system and adapter are disclosed. The adapter includes a turbine attachment portion having a first geometry arranged to receive a corresponding geometry of a wheelpost of a turbine rotor, and a bucket attachment portion having a second geometry arranged to receive a corresponding geometry of a root portion of a non-metallic turbine bucket. Another adapter includes a turbine attachment portion arranged to receive a plurality of wheelposts of a turbine rotor, and a bucket attachment portion arranged to receive a plurality of non-metallic turbine buckets having single dovetail configuration root portions. The turbine system includes a turbine rotor wheel configured to receive metal buckets, at least one adapter secured to at least one wheelpost on the turbine rotor wheel, and at least one non-metallic bucket secured to the at least one adapter.

  18. ALMA Survey of Lupus Protoplanetary Disks. II. Gas Disk Radii

    Science.gov (United States)

    Ansdell, M.; Williams, J. P.; Trapman, L.; van Terwisga, S. E.; Facchini, S.; Manara, C. F.; van der Marel, N.; Miotello, A.; Tazzari, M.; Hogerheijde, M.; Guidi, G.; Testi, L.; van Dishoeck, E. F.

    2018-05-01

    We present Atacama Large Millimeter/Sub-Millimeter Array (ALMA) Band 6 observations of a complete sample of protoplanetary disks in the young (∼1–3 Myr) Lupus star-forming region, covering the 1.33 mm continuum and the 12CO, 13CO, and C18O J = 2–1 lines. The spatial resolution is ∼0.″25 with a medium 3σ continuum sensitivity of 0.30 mJy, corresponding to M dust ∼ 0.2 M ⊕. We apply Keplerian masking to enhance the signal-to-noise ratios of our 12CO zero-moment maps, enabling measurements of gas disk radii for 22 Lupus disks; we find that gas disks are universally larger than millimeter dust disks by a factor of two on average, likely due to a combination of the optically thick gas emission and the growth and inward drift of the dust. Using the gas disk radii, we calculate the dimensionless viscosity parameter, α visc, finding a broad distribution and no correlations with other disk or stellar parameters, suggesting that viscous processes have not yet established quasi-steady states in Lupus disks. By combining our 1.33 mm continuum fluxes with our previous 890 μm continuum observations, we also calculate the millimeter spectral index, α mm, for 70 Lupus disks; we find an anticorrelation between α mm and millimeter flux for low-mass disks (M dust ≲ 5), followed by a flattening as disks approach α mm ≈ 2, which could indicate faster grain growth in higher-mass disks, but may also reflect their larger optically thick components. In sum, this work demonstrates the continuous stream of new insights into disk evolution and planet formation that can be gleaned from unbiased ALMA disk surveys.

  19. Microfabricated rankine cycle steam turbine for power generation and methods of making the same

    Science.gov (United States)

    Frechette, Luc (Inventor); Muller, Norbert (Inventor); Lee, Changgu (Inventor)

    2009-01-01

    In accordance with the present invention, an integrated micro steam turbine power plant on-a-chip has been provided. The integrated micro steam turbine power plant on-a-chip of the present invention comprises a miniature electric power generation system fabricated using silicon microfabrication technology and lithographic patterning. The present invention converts heat to electricity by implementing a thermodynamic power cycle on a chip. The steam turbine power plant on-a-chip generally comprises a turbine, a pump, an electric generator, an evaporator, and a condenser. The turbine is formed by a rotatable, disk-shaped rotor having a plurality of rotor blades disposed thereon and a plurality of stator blades. The plurality of stator blades are interdigitated with the plurality of rotor blades to form the turbine. The generator is driven by the turbine and converts mechanical energy into electrical energy.

  20. Shock Wave Thermomechanical Processing of Gas Turbine Disks.

    Science.gov (United States)

    1980-11-01

    8217mad .Jcasfe )a runent td te Navy________________________________________ fiF A T RBN IIIOC AuS IATO D99h O WNGRDIN l~asKSg #in 1Nov 19"i CHDL Is...E’lngattim In Area Specimen No. Plate No. Schedule No. (MPa; tkssj iMPa, tksti M, r’ 1 4 1 1089.7 158.o 12676 181.8 19 3 20.5 2 I 1085.5 157 4 1282 ?4 l53

  1. Gas turbine blades and disks. Materials and component behaviour

    International Nuclear Information System (INIS)

    1990-01-01

    This progress report summarizes the research results obtained by the special research programme 339 in the years 1988 and 1989. Emphasis is given to the following aspects and problems: Optimisation of structure, protective coatings, connection between structure parameters and mechanical materials behaviour, tribologic materials and component behaviour, impacts of overall loads, and of stress and deformation state in the inelastic regime under mechanical and thermal load, and impacts of the manufacturing process on component behaviour, quality assurance. Eleven of the fifteen papers of the report have been separately analysed for the ENERGY database, and thirteen for the DELURA database. (orig./MM) With 191 figs., 13 tabs [de

  2. HIGH EFFICIENCY TURBINE

    OpenAIRE

    VARMA, VIJAYA KRUSHNA

    2012-01-01

    Varma designed ultra modern and high efficiency turbines which can use gas, steam or fuels as feed to produce electricity or mechanical work for wide range of usages and applications in industries or at work sites. Varma turbine engines can be used in all types of vehicles. These turbines can also be used in aircraft, ships, battle tanks, dredgers, mining equipment, earth moving machines etc, Salient features of Varma Turbines. 1. Varma turbines are simple in design, easy to manufac...

  3. Turbine maintenance and modernization

    Energy Technology Data Exchange (ETDEWEB)

    Unga, E. [Teollisuuden Voima Oy, Olkiluoto (Finland)

    1998-12-31

    The disturbance-free operation of the turbine plant plays an important role in reaching good production results. In the turbine maintenance of the Olkiluoto nuclear power plant the lifetime and efficiency of turbine components and the lifetime costs are taken into account in determining the turbine maintenance and modernization/improvement program. The turbine maintenance program and improvement/modernization measures taken in the plant units are described in this presentation. (orig.)

  4. Turbine maintenance and modernization

    Energy Technology Data Exchange (ETDEWEB)

    Unga, E [Teollisuuden Voima Oy, Olkiluoto (Finland)

    1999-12-31

    The disturbance-free operation of the turbine plant plays an important role in reaching good production results. In the turbine maintenance of the Olkiluoto nuclear power plant the lifetime and efficiency of turbine components and the lifetime costs are taken into account in determining the turbine maintenance and modernization/improvement program. The turbine maintenance program and improvement/modernization measures taken in the plant units are described in this presentation. (orig.)

  5. WIND-DRIVEN ACCRETION IN TRANSITIONAL PROTOSTELLAR DISKS

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lile; Goodman, Jeremy J. [Princeton University Observatory, Princeton, NJ 08544 (United States)

    2017-01-20

    Transitional protostellar disks have inner cavities that are heavily depleted in dust and gas, yet most of them show signs of ongoing accretion, often at rates comparable to full disks. We show that recent constraints on the gas surface density in a few well-studied disk cavities suggest that the accretion speed is at least transsonic. We propose that this is the natural result of accretion driven by magnetized winds. Typical physical conditions of the gas inside these cavities are estimated for plausible X-ray and FUV radiation fields. The gas near the midplane is molecular and predominantly neutral, with a dimensionless ambipolar parameter in the right general range for wind solutions of the type developed by Königl, Wardle, and others. That is to say, the density of ions and electrons is sufficient for moderately good coupling to the magnetic field, but it is not so good that the magnetic flux needs to be dragged inward by the accreting neutrals.

  6. Numerical analysis of turbine blade tip treatments

    Science.gov (United States)

    Gopalaswamy, Nath S.; Whitaker, Kevin W.

    1992-01-01

    Three-dimensional solutions of the Navier-Stokes equations for a turbine blade with a turning angle of 180 degrees have been computed, including blade tip treatments involving cavities. The geometry approximates a preliminary design for the GGOT (Generic Gas Oxidizer Turbine). The data presented here will be compared with experimental data to be obtained from a linear cascade using original GGOT blades. Results have been computed for a blade with 1 percent clearance, based on chord, and three different cavity sizes. All tests were conducted at a Reynolds number of 4 x 10 exp 7. The grid contains 39,440 points with 10 spanwise planes in the tip clearance region of 5.008E-04 m. Streamline plots and velocity vectors together with velocity divergence plots reveal the general flow behavior in the clearance region. Blade tip temperature calculations suggest placement of a cavity close to the upstream side of the blade tip for reduction of overall blade tip temperature. The solutions do not account for the relative motion between the endwall and the turbine blade. The solutions obtained are generally consistent with previous work done in this area,

  7. Brown dwarf disks with ALMA

    Energy Technology Data Exchange (ETDEWEB)

    Ricci, L.; Isella, A. [Department of Astronomy, California Institute of Technology, MC 249-17, Pasadena, CA 91125 (United States); Testi, L.; De Gregorio-Monsalvo, I. [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching (Germany); Natta, A. [INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy); Scholz, A., E-mail: lricci@astro.caltech.edu [School of Cosmic Physics, Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2 (Ireland)

    2014-08-10

    We present Atacama Large Millimeter/submillimeter Array continuum and spectral line data at 0.89 mm and 3.2 mm for three disks surrounding young brown dwarfs and very low mass stars in the Taurus star forming region. Dust thermal emission is detected and spatially resolved for all the three disks, while CO(J = 3-2) emission is seen in two disks. We analyze the continuum visibilities and constrain the disks' physical structure in dust. The results of our analysis show that the disks are relatively large; the smallest one has an outer radius of about 70 AU. The inferred disk radii, radial profiles of the dust surface density, and disk to central object mass ratios lie within the ranges found for disks around more massive young stars. We derive from our observations the wavelength dependence of the millimeter dust opacity. In all the three disks, data are consistent with the presence of grains with at least millimeter sizes, as also found for disks around young stars, and confirm that the early stages of the solid growth toward planetesimals occur also around very low-mass objects. We discuss the implications of our findings on models of solids evolution in protoplanetary disks, the main mechanisms proposed for the formation of brown dwarfs and very low-mass stars, as well as the potential of finding rocky and giant planets around very low-mass objects.

  8. Numerical simulation of the aerodynamic field in complex terrain wind farm based on actuator disk model

    DEFF Research Database (Denmark)

    Xu, Chang; Li, Chen Qi; Han, Xing Xing

    2015-01-01

    Study on the aerodynamic field in complex terrain is significant to wind farm micro-sitting and wind power prediction. This paper modeled the wind turbine through an actuator disk model, and solved the aerodynamic field by CFD to study the influence of meshing, boundary conditions and turbulence ...

  9. Evolution of magnetic disk subsystems

    Science.gov (United States)

    Kaneko, Satoru

    1994-06-01

    The higher recording density of magnetic disk realized today has brought larger storage capacity per unit and smaller form factors. If the required access performance per MB is constant, the performance of large subsystems has to be several times better. This article describes mainly the technology for improving the performance of the magnetic disk subsystems and the prospects of their future evolution. Also considered are 'crosscall pathing' which makes the data transfer channel more effective, 'disk cache' which improves performance coupling with solid state memory technology, and 'RAID' which improves the availability and integrity of disk subsystems by organizing multiple disk drives in a subsystem. As a result, it is concluded that since the performance of the subsystem is dominated by that of the disk cache, maximation of the performance of the disk cache subsystems is very important.

  10. Herniated disk disease

    International Nuclear Information System (INIS)

    Ross, J.S.; Masaryk, T.J.; Modic, M.T.; Bohlman, H.; Wilber, G.; Carter, J.

    1988-01-01

    Thirty patients with symptoms of disk herniation and no previous surgery were examined with Gd-DTPA-enhanced MR imaging. Studies obtained before and after administration of Gd-DTPA included the following sequences: sagittal and axial spin echo (SE) 500/17 (repetition time, msec/echo time, msec), sagittal SE 2,000/60, sagittal FLASH 200/13/60. Studies were interpreted separately for presence of extradural disease (EDD) characterized by morphology, mass effect, and enhancement. Post Gd-DTPA diagnoses were: normal, n = 1; herniation, n = 28; neoplasm, n = 1. Tissue diagnosis was obtained in 13. The Gd-DTPA examination correctly changed the diagnosis in one case, provided increased confidence in the diagnosis in four, and was equivalent to the precontrast study in eight. Increased conspicuity of EDD with Gd-DTPA was related to the enhancement of epidural space analogous to IV CT and enhancement of scar surrounding disk herniation. Histologically, this scar was identical to that seen in postoperative spines, Gd-DTPA appears to be a useful adjunct in cervical and thoracic degenerative disk disease

  11. Using machine learning to predict wind turbine power output

    International Nuclear Information System (INIS)

    Clifton, A; Kilcher, L; Lundquist, J K; Fleming, P

    2013-01-01

    Wind turbine power output is known to be a strong function of wind speed, but is also affected by turbulence and shear. In this work, new aerostructural simulations of a generic 1.5 MW turbine are used to rank atmospheric influences on power output. Most significant is the hub height wind speed, followed by hub height turbulence intensity and then wind speed shear across the rotor disk. These simulation data are used to train regression trees that predict the turbine response for any combination of wind speed, turbulence intensity, and wind shear that might be expected at a turbine site. For a randomly selected atmospheric condition, the accuracy of the regression tree power predictions is three times higher than that from the traditional power curve methodology. The regression tree method can also be applied to turbine test data and used to predict turbine performance at a new site. No new data are required in comparison to the data that are usually collected for a wind resource assessment. Implementing the method requires turbine manufacturers to create a turbine regression tree model from test site data. Such an approach could significantly reduce bias in power predictions that arise because of the different turbulence and shear at the new site, compared to the test site. (letter)

  12. Airfoil for a gas turbine engine

    Science.gov (United States)

    Liang, George [Palm City, FL

    2011-05-24

    An airfoil is provided for a turbine of a gas turbine engine. The airfoil comprises: an outer structure comprising a first wall including a leading edge, a trailing edge, a pressure side, and a suction side; an inner structure comprising a second wall spaced from the first wall and at least one intermediate wall; and structure extending between the first and second walls so as to define first and second gaps between the first and second walls. The second wall and the at least one intermediate wall define at least one pressure side supply cavity and at least one suction side supply cavity. The second wall may include at least one first opening near the leading edge of the first wall. The first opening may extend from the at least one pressure side supply cavity to the first gap. The second wall may further comprise at least one second opening near the trailing edge of the outer structure. The second opening may extend from the at least one suction side supply cavity to the second gap. The first wall may comprise at least one first exit opening extending from the first gap through the pressure side of the first wall and at least one second exit opening extending from the second gap through the suction side of the second wall.

  13. The LHC superconducting cavities

    CERN Document Server

    Boussard, Daniel; Häbel, E; Kindermann, H P; Losito, R; Marque, S; Rödel, V; Stirbet, M

    1999-01-01

    The LHC RF system, which must handle high intensity (0.5 A d.c.) beams, makes use of superconducting single-cell cavities, best suited to minimizing the effects of periodic transient beam loading. There will be eight cavities per beam, each capable of delivering 2 MV (5 MV/m accelerating field) at 400 MHz. The cavities themselves are now being manufactured by industry, using niobium-on-copper technology which gives full satisfaction at LEP. A cavity unit includes a helium tank (4.5 K operating temperature) built around a cavity cell, RF and HOM couplers and a mechanical tuner, all housed in a modular cryostat. Four-unit modules are ultimately foreseen for the LHC (two per beam), while at present a prototype version with two complete units is being extensively tested. In addition to a detailed description of the cavity and its ancillary equipment, the first test results of the prototype will be reported.

  14. LEP copper accelerating cavities

    CERN Multimedia

    Laurent Guiraud

    1999-01-01

    These copper cavities were used to generate the radio frequency electric field that was used to accelerate electrons and positrons around the 27-km Large Electron-Positron (LEP) collider at CERN, which ran from 1989 to 2000. The copper cavities were gradually replaced from 1996 with new superconducting cavities allowing the collision energy to rise from 90 GeV to 200 GeV by mid-1999.

  15. Steam turbine cycle

    International Nuclear Information System (INIS)

    Okuzumi, Naoaki.

    1994-01-01

    In a steam turbine cycle, steams exhausted from the turbine are extracted, and they are connected to a steam sucking pipe of a steam injector, and a discharge pipe of the steam injector is connected to an inlet of a water turbine. High pressure discharge water is obtained from low pressure steams by utilizing a pressurizing performance of the steam injector and the water turbine is rotated by the high pressure water to generate electric power. This recover and reutilize discharged heat of the steam turbine effectively, thereby enabling to improve heat efficiency of the steam turbine cycle. (T.M.)

  16. The swirl turbine

    Science.gov (United States)

    Haluza, M.; Pochylý, F.; Rudolf, P.

    2012-11-01

    In the article is introduced the new type of the turbine - swirl turbine. This turbine is based on opposite principle than Kaplan turbine. Euler equation is satisfied in the form gHηh = -u2vu2. From this equation is seen, that inflow of liquid into the runner is without rotation and on the outflow is a rotation of liquid opposite of rotation of runner. This turbine is suitable for small head and large discharge. Some constructional variants of this turbine are introduced in the article and theoretical aspects regarding losses in the draft tube. The theory is followed by computational simulations in Fluent and experiments using laser Doppler anemometry.

  17. Progress of a Cross-Correlation Based Optical Strain Measurement Technique for Detecting Radial Growth on a Rotating Disk

    Science.gov (United States)

    Clem, Michelle M.; Abdul-Aziz, Ali; Woike, Mark R.; Fralick, Gustave C.

    2015-01-01

    The modern turbine engine operates in a harsh environment at high speeds and is repeatedly exposed to combined high mechanical and thermal loads. The cumulative effects of these external forces lead to high stresses and strains on the engine components, such as the rotating turbine disks, which may eventually lead to a catastrophic failure if left undetected. The operating environment makes it difficult to use conventional strain gauges, therefore, non-contact strain measurement techniques is of interest to NASA and the turbine engine community. This presentation describes one such approach; the use of cross correlation analysis to measure strain experienced by the engine turbine disk with the goal of assessing potential faults and damage.

  18. RINGED ACCRETION DISKS: INSTABILITIES

    Energy Technology Data Exchange (ETDEWEB)

    Pugliese, D.; Stuchlík, Z., E-mail: d.pugliese.physics@gmail.com, E-mail: zdenek.stuchlik@physics.cz [Institute of Physics and Research Centre of Theoretical Physics and Astrophysics, Faculty of Philosophy and Science, Silesian University in Opava, Bezručovo náměstí 13, CZ-74601 Opava (Czech Republic)

    2016-04-01

    We analyze the possibility that several instability points may be formed, due to the Paczyński mechanism of violation of mechanical equilibrium, in the orbiting matter around a supermassive Kerr black hole. We consider a recently proposed model of a ringed accretion disk, made up by several tori (rings) that can be corotating or counter-rotating relative to the Kerr attractor due to the history of the accretion process. Each torus is governed by the general relativistic hydrodynamic Boyer condition of equilibrium configurations of rotating perfect fluids. We prove that the number of the instability points is generally limited and depends on the dimensionless spin of the rotating attractor.

  19. CMC blade with pressurized internal cavity for erosion control

    Science.gov (United States)

    Garcia-Crespo, Andres; Goike, Jerome Walter

    2016-02-02

    A ceramic matrix composite blade for use in a gas turbine engine having an airfoil with leading and trailing edges and pressure and suction side surfaces, a blade shank secured to the lower end of each airfoil, one or more interior fluid cavities within the airfoil having inlet flow passages at the lower end which are in fluid communication with the blade shank, one or more passageways in the blade shank corresponding to each one of the interior fluid cavities and a fluid pump (or compressor) that provides pressurized fluid (nominally cool, dry air) to each one of the interior fluid cavities in each airfoil. The fluid (e.g., air) is sufficient in pressure and volume to maintain a minimum fluid flow to each of the interior fluid cavities in the event of a breach due to foreign object damage.

  20. Audit: Automated Disk Investigation Toolkit

    Directory of Open Access Journals (Sweden)

    Umit Karabiyik

    2014-09-01

    Full Text Available Software tools designed for disk analysis play a critical role today in forensics investigations. However, these digital forensics tools are often difficult to use, usually task specific, and generally require professionally trained users with IT backgrounds. The relevant tools are also often open source requiring additional technical knowledge and proper configuration. This makes it difficult for investigators without some computer science background to easily conduct the needed disk analysis. In this paper, we present AUDIT, a novel automated disk investigation toolkit that supports investigations conducted by non-expert (in IT and disk technology and expert investigators. Our proof of concept design and implementation of AUDIT intelligently integrates open source tools and guides non-IT professionals while requiring minimal technical knowledge about the disk structures and file systems of the target disk image.

  1. THE SEEDS DIRECT IMAGING SURVEY FOR PLANETS AND SCATTERED DUST EMISSION IN DEBRIS DISK SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    Janson, Markus; Brandt, Timothy D. [Department of Astrophysical Sciences, Princeton University, NJ 08544 (United States); Moro-Martin, Amaya [Department of Astrophysics, CAB (INTA-CSIC), Instituto Nacional de Tecnica Aerospacial, Torrejonde Ardoz, E-28850 Madrid (Spain); Usuda, Tomonori; Kudo, Tomoyuki; Egner, Sebastian [Subaru Telescope, 650 North Aohoku Place, Hilo, HI 96720 (United States); Thalmann, Christian [Astronomical Institute ' ' Anton Pannekoek' ' , University of Amsterdam, Science Park 904, 1098-XH Amsterdam (Netherlands); Carson, Joseph C. [Department of Physics and Astronomy, College of Charleston, 58 Coming Street, Charleston, SC 29424 (United States); Goto, Miwa [Universitaets-Sternwarte Muenchen, Ludwig-Maximilians-Universitaet, Scheinerstr. 1, D-81679 Munich (Germany); Currie, Thayne [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, M5S 3H4 Toronto, ON (Canada); McElwain, M. W. [Exoplanets and Stellar Astrophysics Laboratory, Code 667, Goddard Space Flight Center, Greenbelt, MD 2071 (United States); Itoh, Yoichi [Nishi-Harima Astronomical Observatory, Center for Astronomy, University of Hyogo, 407-2 Nishigaichi, Sayo, Hyogo 679-5313 (Japan); Fukagawa, Misato [Department of Earth and Space Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043 (Japan); Crepp, Justin [Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46556 (United States); Kuzuhara, Masayuki; Hashimoto, Jun; Kusakabe, Nobuhiko [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Abe, Lyu [Laboratoire Lagrange, UMR7239, University of Nice-Sophia Antipolis, CNRS, Observatoire de la Cote d' Azur, F-06300 Nice (France); Brandner, Wolfgang; Feldt, Markus, E-mail: janson@astro.princeton.edu [Max Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany); and others

    2013-08-10

    Debris disks around young main-sequence stars often have gaps and cavities which for a long time have been interpreted as possibly being caused by planets. In recent years, several giant planet discoveries have been made in systems hosting disks of precisely this nature, further implying that interactions with planets could be a common cause of such disk structures. As part of the SEEDS high-contrast imaging survey, we are surveying a population of debris-disk-hosting stars with gaps and cavities implied by their spectral energy distributions, in order to attempt to spatially resolve the disk as well as to detect any planets that may be responsible for the disk structure. Here, we report on intermediate results from this survey. Five debris disks have been spatially resolved, and a number of faint point sources have been discovered, most of which have been tested for common proper motion, which in each case has excluded physical companionship with the target stars. From the detection limits of the 50 targets that have been observed, we find that {beta} Pic b-like planets ({approx}10 M{sub jup} planets around G-A-type stars) near the gap edges are less frequent than 15%-30%, implying that if giant planets are the dominant cause of these wide (27 AU on average) gaps, they are generally less massive than {beta} Pic b.

  2. Dust evolution in protoplanetary disks

    OpenAIRE

    Gonzalez , Jean-François; Fouchet , Laure; T. Maddison , Sarah; Laibe , Guillaume

    2007-01-01

    6 pages, 5 figures, to appear in the Proceedings of IAU Symp. 249: Exoplanets: Detection, Formation and Dynamics (Suzhou, China); International audience; We investigate the behaviour of dust in protoplanetary disks under the action of gas drag using our 3D, two-fluid (gas+dust) SPH code. We present the evolution of the dust spatial distribution in global simulations of planetless disks as well as of disks containing an already formed planet. The resulting dust structures vary strongly with pa...

  3. Fallback disks & magnetars: prospects & possibilities

    Science.gov (United States)

    Alpar, M. A.

    Some bound matter in the form of a fallback disk may be an initial parameter of isolated neutron stars at birth which along with the initial rotation rate and dipole and higher multipole magnetic moments determines the evolution of neutron stars and the categories into which they fall This talk reviews the strengths and difficulties of fallback disk models in explaining properties of isolated neutron stars of different categories Evidence for and observational limits on fallback disks will also be discussed

  4. IBM 3390 Hard Disk Platter

    CERN Multimedia

    1991-01-01

    The 3390 disks rotated faster than those in the previous model 3380. Faster disk rotation reduced rotational delay (ie. the time required for the correct area of the disk surface to move to the point where data could be read or written). In the 3390's initial models, the average rotational delay was reduced to 7.1 milliseconds from 8.3 milliseconds for the 3380 family.

  5. STELLAR MASS DEPENDENT DISK DISPERSAL

    International Nuclear Information System (INIS)

    Kennedy, Grant M.; Kenyon, Scott J.

    2009-01-01

    We use published optical spectral and infrared (IR) excess data from nine young clusters and associations to study the stellar mass dependent dispersal of circumstellar disks. All clusters older than ∼3 Myr show a decrease in disk fraction with increasing stellar mass for solar to higher mass stars. This result is significant at about the 1σ level in each cluster. For the complete set of clusters we reject the null hypothesis-that solar and intermediate-mass stars lose their disks at the same rate-with 95%-99.9% confidence. To interpret this behavior, we investigate the impact of grain growth, binary companions, and photoevaporation on the evolution of disk signatures. Changes in grain growth timescales at fixed disk temperature may explain why early-type stars with IR excesses appear to evolve faster than their later-type counterparts. Little evidence that binary companions affect disk evolution suggests that photoevaporation is the more likely mechanism for disk dispersal. A simple photoevaporation model provides a good fit to the observed disk fractions for solar and intermediate-mass stars. Although the current mass-dependent disk dispersal signal is not strong, larger and more complete samples of clusters with ages of 3-5 Myr can improve the significance and provide better tests of theoretical models. In addition, the orbits of extra-solar planets can constrain models of disk dispersal and migration. We suggest that the signature of stellar mass dependent disk dispersal due to photoevaporation may be present in the orbits of observed extra-solar planets. Planets orbiting hosts more massive than ∼1.6 M sun may have larger orbits because the disks in which they formed were dispersed before they could migrate.

  6. Hole-y Debris Disks, Batman! Where are the planets?

    Science.gov (United States)

    Bailey, V.; Meshkat, T.; Hinz, P.; Kenworthy, M.; Su, K. Y. L.

    2014-03-01

    Giant planets at wide separations are rare and direct imaging surveys are resource-intensive, so a cheaper marker for the presence of giant planets is desirable. One intriguing possibility is to use the effect of planets on their host stars' debris disks. Theoretical studies indicate giant planets can gravitationally carve sharp boundaries and gaps in their disks; this has been seen for HR 8799, β Pic, and tentatively for HD 95086 (Su et al. 2009, Lagrange et al. 2010, Moor et al. 2013). If more broadly demonstrated, this link could help guide target selection for next generation direct imaging surveys. Using Spitzer MIPS/IRS spectral energy distributions (SEDs), we identify several dozen systems with two-component and/or large inner cavity disks (aka Hole-y Debris Disks). With LBT/LBTI, VLT/NaCo, GeminiS/NICI, MMT/Clio and Magellan/Clio, we survey a subset these SEDselected targets (~20). In contrast to previous disk-selected planet surveys (e.g.: Janson et al. 2013, Wahhaj et al. 2013) we image primarily in the thermal IR (L'-band), where planet-to-star contrast is more favorable and background contaminants less numerous. Thus far, two of our survey targets host planet-mass companions, both of which were discovered in L'-band after they were unrecognized or undetectable in H-band. For each system in our sample set, we will investigate whether the known companions and/or companions below our detection threshold could be responsible for the disk architecture. Ultimately, we will increase our effective sample size by incorporating detection limits from surveys that have independently targeted some of our systems of interest. In this way we will refine the conditions under which disk SED-based target selection is likely to be useful and valid.

  7. Study on the dependence of the resonance frequency of accelerators on the cavities internal diameter

    International Nuclear Information System (INIS)

    Serrao, V.A.; Franco, M.A.R.; Fuhrmann, C.

    1988-05-01

    The resonance frequencies of individual cavities and of a six cell disk-loaded prototype of an accelerating structure were measured as a function of cavity inner diameter. A linear relationship between the indidual cavity frequency and the six cell stack 2Π/3 mode frequency was obtained that will be very useful during the final tuning of the accelerating strutures of the IEAV linac. The dispersion diagrams were also obtained for various internal cavity diameters; these diagrams were utilized to estimate the group velocity and the RF filling time of the accelerating structure. (author) [pt

  8. Aerodynamics of Wind Turbines

    DEFF Research Database (Denmark)

    Hansen, Martin Otto Laver

    Aerodynamics of Wind Turbines is the established essential text for the fundamental solutions to efficient wind turbine design. Now in its second edition, it has been entirely updated and substantially extended to reflect advances in technology, research into rotor aerodynamics and the structural...... response of the wind turbine structure. Topics covered include increasing mass flow through the turbine, performance at low and high wind speeds, assessment of the extreme conditions under which the turbine will perform and the theory for calculating the lifetime of the turbine. The classical Blade Element...... Momentum method is also covered, as are eigenmodes and the dynamic behavior of a turbine. The new material includes a description of the effects of the dynamics and how this can be modeled in an aeroelastic code, which is widely used in the design and verification of modern wind turbines. Further...

  9. Aerodynamics of wind turbines

    DEFF Research Database (Denmark)

    Hansen, Martin Otto Laver

    Aerodynamics of Wind Turbines is the established essential text for the fundamental solutions to efficient wind turbine design. Now in its third edition, it has been substantially updated with respect to structural dynamics and control. The new control chapter now includes details on how to design...... Turbines (VAWT). Topics covered include increasing mass flow through the turbine, performance at low and high wind speeds, assessment of the extreme conditions under which the turbine will perform and the theory for calculating the lifetime of the turbine. The classical Blade Element Momentum method...... is also covered, as are eigenmodes and the dynamic behaviour of a turbine. The book describes the effects of the dynamics and how this can be modelled in an aeroelastic code, which is widely used in the design and verification of modern wind turbines. Furthermore, it examines how to calculate...

  10. TurbinAID

    International Nuclear Information System (INIS)

    Moradian, M.A.; Chow, M.P.; Osborne, R.L.; Jenkins, M.A.

    1991-01-01

    The Westinghouse Turbine Artificial Intelligence Diagnostics system or TurbinAID, can diagnose both thermodynamic and mechanical component anomalies within the turbine, and around the turbine cycle. any monitoring system can detect that a variable is in an abnormal state, but TurbinAID can also indicate the cause, and provide recommended corrective action(s). The TurbinAID Expert Systems utilize multiple sensor and variable inputs, and their interdependencies in the generation of a diagnosis. The system performs sensor validation as part of the data acquisition scheme. The TurbinAID system has been in operation for several years. This paper describes the monitoring and diagnostic functions provided by TurbinAID, and how the utility industry both nuclear and fossil, can utilize the system to enhance unit operation

  11. [Disk calcifications in children].

    Science.gov (United States)

    Schmit, P; Fauré, C; Denarnaud, L

    1985-05-01

    It is not unusual for intervertebral disk calcifications to be detected in pediatric practice, the 150 or so cases reported in the literature probably representing only a small proportion of lesions actually diagnosed. Case reports of 33 children with intervertebral disk calcifications were analyzed. In the majority of these patients (31 of 33) a diagnosis of "idiopathic" calcifications had been made, the cervical localization of the lesions being related to repeated ORL infections and/or trauma. A pre-existing pathologic factor was found in two cases (one child with juvenile rheumatoid arthritis treated by corticoids and one child with Williams and Van Beuren's syndrome). An uncomplicated course was noted in 31 cases, the symptomatology (pain, spinal stiffness and febricula) improving after several days. Complications developed in two cases: one child had very disabling dysphagia due to an anteriorly protruding cervical herniated disc and surgery was necessary; the other child developed cervicobrachial neuralgia due to herniated disc protrusion into the cervical spinal canal, but symptoms regressed within several days although calcifications persisted unaltered. These findings and the course of the rare complications documented in the literature suggest the need for the most conservative treatment possible in cases of disc calcifications in children.

  12. Disk storage at CERN

    CERN Document Server

    Mascetti, L; Chan, B; Espinal, X; Fiorot, A; Labrador, H Gonz; Iven, J; Lamanna, M; Presti, G Lo; Mościcki, JT; Peters, AJ; Ponce, S; Rousseau, H; van der Ster, D

    2015-01-01

    CERN IT DSS operates the main storage resources for data taking and physics analysis mainly via three system: AFS, CASTOR and EOS. The total usable space available on disk for users is about 100 PB (with relative ratios 1:20:120). EOS actively uses the two CERN Tier0 centres (Meyrin and Wigner) with 50:50 ratio. IT DSS also provide sizeable on-demand resources for IT services most notably OpenStack and NFS-based clients: this is provided by a Ceph infrastructure (3 PB) and few proprietary servers (NetApp). We will describe our operational experience and recent changes to these systems with special emphasis to the present usages for LHC data taking, the convergence to commodity hardware (nodes with 200-TB each with optional SSD) shared across all services. We also describe our experience in coupling commodity and home-grown solution (e.g. CERNBox integration in EOS, Ceph disk pools for AFS, CASTOR and NFS) and finally the future evolution of these systems for WLCG and beyond.

  13. Disk storage at CERN

    Science.gov (United States)

    Mascetti, L.; Cano, E.; Chan, B.; Espinal, X.; Fiorot, A.; González Labrador, H.; Iven, J.; Lamanna, M.; Lo Presti, G.; Mościcki, JT; Peters, AJ; Ponce, S.; Rousseau, H.; van der Ster, D.

    2015-12-01

    CERN IT DSS operates the main storage resources for data taking and physics analysis mainly via three system: AFS, CASTOR and EOS. The total usable space available on disk for users is about 100 PB (with relative ratios 1:20:120). EOS actively uses the two CERN Tier0 centres (Meyrin and Wigner) with 50:50 ratio. IT DSS also provide sizeable on-demand resources for IT services most notably OpenStack and NFS-based clients: this is provided by a Ceph infrastructure (3 PB) and few proprietary servers (NetApp). We will describe our operational experience and recent changes to these systems with special emphasis to the present usages for LHC data taking, the convergence to commodity hardware (nodes with 200-TB each with optional SSD) shared across all services. We also describe our experience in coupling commodity and home-grown solution (e.g. CERNBox integration in EOS, Ceph disk pools for AFS, CASTOR and NFS) and finally the future evolution of these systems for WLCG and beyond.

  14. Cavity design programs

    International Nuclear Information System (INIS)

    Nelson, E.M.

    1996-01-01

    Numerous computer programs are available to help accelerator physicists and engineers model and design accelerator cavities and other microwave components. This article discusses the problems these programs solve and the principles upon which these programs are based. Some examples of how these programs are used in the design of accelerator cavities are also given

  15. Cavity quantum electrodynamics

    International Nuclear Information System (INIS)

    Walther, Herbert; Varcoe, Benjamin T H; Englert, Berthold-Georg; Becker, Thomas

    2006-01-01

    This paper reviews the work on cavity quantum electrodynamics of free atoms. In recent years, cavity experiments have also been conducted on a variety of solid-state systems resulting in many interesting applications, of which microlasers, photon bandgap structures and quantum dot structures in cavities are outstanding examples. Although these phenomena and systems are very interesting, discussion is limited here to free atoms and mostly single atoms because these systems exhibit clean quantum phenomena and are not disturbed by a variety of other effects. At the centre of our review is the work on the one-atom maser, but we also give a survey of the entire field, using free atoms in order to show the large variety of problems dealt with. The cavity interaction can be separated into two main regimes: the weak coupling in cavity or cavity-like structures with low quality factors Q and the strong coupling when high-Q cavities are involved. The weak coupling leads to modification of spontaneous transitions and level shifts, whereas the strong coupling enables one to observe a periodic exchange of photons between atoms and the radiation field. In this case, atoms and photons are entangled, this being the basis for a variety of phenomena observed, some of them leading to interesting applications in quantum information processing. The cavity experiments with free atoms reached a new domain with the advent of experiments in the visible spectral region. A review on recent achievements in this area is also given

  16. Turbulence and wind turbines

    DEFF Research Database (Denmark)

    Brand, Arno J.; Peinke, Joachim; Mann, Jakob

    2011-01-01

    The nature of turbulent flow towards, near and behind a wind turbine, the effect of turbulence on the electricity production and the mechanical loading of individual and clustered wind turbines, and some future issues are discussed.......The nature of turbulent flow towards, near and behind a wind turbine, the effect of turbulence on the electricity production and the mechanical loading of individual and clustered wind turbines, and some future issues are discussed....

  17. Formation of coronal cavities

    International Nuclear Information System (INIS)

    An, C.H.; Suess, S.T.; Tandberg-Hanssen, E.; Steinolfson, R.S.

    1986-01-01

    A theoretical study of the formation of a coronal cavity and its relation to a quiescent prominence is presented. It is argued that the formation of a cavity is initiated by the condensation of plasma which is trapped by the coronal magnetic field in a closed streamer and which then flows down to the chromosphere along the field lines due to lack of stable magnetic support against gravity. The existence of a coronal cavity depends on the coronal magnetic field strength; with low strength, the plasma density is not high enough for condensation to occur. Furthermore, we suggest that prominence and cavity material is supplied from the chromospheric level. Whether a coronal cavity and a prominence coexist depends on the magnetic field configuration; a prominence requires stable magnetic support

  18. ANT tuner retrofit for LEB cavity

    International Nuclear Information System (INIS)

    Walling, L.; Goren, Y.; Kwiatkowski, S.

    1994-03-01

    This report describes a ferrite tuner design for the LEB cavity that utilizes techniques for bonding ferrite to metallic cooling plates that is utilized in the high-power rf and microwave industry. A test tuner was designed to fit into the existing LEB-built magnet and onto the Grimm LEB Cavity. It will require a new vacuum window in order to attain maximal tuning range and high voltage capability and a new center conductor of longer length and a different vacuum window connection than the Grimm center conductor. However, the new center conductor will be essentially identical to the Grimm center conductor in its basic construction and in the way it connects to the stand for support. The tuner is mechanically very similar to high-power stacked circulators built by ANT of Germany and was designed according to ANT's established engineering and design criteria and SSC LEB tuning and power requirements. The tuner design incorporates thin tiles of ferrite glued using a high-radiation-resistance epoxy to copper-plated stainless steel cooling plates of thickness 6.5 mm with water cooling channels inside the plates. The cooling plates constitute 16 pie-shaped segments arranged in a disk. They are electrically isolated from each other to suppress eddy currents. Five of these disks are arranged in parallel with high-pressure rf contacts between the plates at the outer radius. The end walls are slotted copper-plated stainless steel of thickness 3 mm

  19. Sliding vane geometry turbines

    Science.gov (United States)

    Sun, Harold Huimin; Zhang, Jizhong; Hu, Liangjun; Hanna, Dave R

    2014-12-30

    Various systems and methods are described for a variable geometry turbine. In one example, a turbine nozzle comprises a central axis and a nozzle vane. The nozzle vane includes a stationary vane and a sliding vane. The sliding vane is positioned to slide in a direction substantially tangent to an inner circumference of the turbine nozzle and in contact with the stationary vane.

  20. STRUCTURE AND EVOLUTION OF CIRCUMBINARY DISKS AROUND SUPERMASSIVE BLACK HOLE BINARIES

    International Nuclear Information System (INIS)

    Rafikov, Roman R.

    2013-01-01

    We explore properties of circumbinary disks around supermassive black hole (SMBH) binaries in centers of galaxies by reformulating standard viscous disk evolution in terms of the viscous angular momentum flux F J . If the binary stops gas inflow and opens a cavity in the disk, then the inner disk evolves toward a constant-F J (rather than a constant M-dot ) state. We compute disk properties in different physical regimes relevant for SMBH binaries, focusing on the gas-assisted evolution of systems starting at separations 10 –4 – 10 –2 pc, and find the following. (1) Mass pileup at the inner disk edge caused by the tidal barrier accelerates binary inspiral. (2) Binaries can be forced to merge even by a disk with a mass below that of the secondary. (3) Torque on the binary is set non-locally, at radii far larger than the binary semi-major axis; its magnitude does not reflect disk properties in the vicinity of the binary. (4) Binary inspiral exhibits hysteresis—it depends on the past evolution of the disk. (5) The Eddington limit can be important for circumbinary disks even if they accrete at sub-Eddington rates, but only at late stages of the inspiral. (6) Gas overflow across the orbit of the secondary can be important for low secondary mass, high- M-dot systems, but mainly during the inspiral phase dominated by the gravitational wave emission. (7) Circumbinary disks emit more power and have harder spectra than constant M-dot disks; their spectra are very sensitive to the amount of overflow across the secondary orbit

  1. Turbine airfoil fabricated from tapered extrusions

    Science.gov (United States)

    Marra, John J

    2013-07-16

    An airfoil (30) and fabrication process for turbine blades with cooling channels (26). Tapered tubes (32A-32D) are bonded together in a parallel sequence, forming a leading edge (21), a trailing edge (22), and pressure and suction side walls (23, 24) connected by internal ribs (25). The tapered tubes may be extruded without camber to simplify the extrusion process, then bonded along matching surfaces (34), forming a non-cambered airfoil (28), which may be cambered in a hot forming process and cut (48) to length. The tubes may have tapered walls that are thinner at the blade tip (T1) than at the base (T2), reducing mass. A cap (50) may be attached to the blade tip. A mounting lug (58) may be forged (60) on the airfoil base and then machined, completing the blade for mounting in a turbine rotor disk.

  2. Computational study of the effects of shroud geometric variation on turbine performance in a 1.5-stage high-loaded turbine

    Science.gov (United States)

    Jia, Wei; Liu, Huoxing

    2013-10-01

    Generally speaking, main flow path of gas turbine is assumed to be perfect for standard 3D computation. But in real engine, the turbine annulus geometry is not completely smooth for the presence of the shroud and associated cavity near the end wall. Besides, shroud leakage flow is one of the dominant sources of secondary flow in turbomachinery, which not only causes a deterioration of useful work but also a penalty on turbine efficiency. It has been found that neglect shroud leakage flow makes the computed velocity profiles and loss distribution significantly different to those measured. Even so, the influence of shroud leakage flow is seldom taken into consideration during the routine of turbine design due to insufficient understanding of its impact on end wall flows and turbine performance. In order to evaluate the impact of tip shroud geometry on turbine performance, a 3D computational investigation for 1.5-stage turbine with shrouded blades was performed in this paper. The following geometry parameters were varied respectively: Inlet cavity length and exit cavity length

  3. Wind turbine/generator set and method of making same

    Science.gov (United States)

    Bevington, Christopher M.; Bywaters, Garrett L.; Coleman, Clint C.; Costin, Daniel P.; Danforth, William L.; Lynch, Jonathan A.; Rolland, Robert H.

    2013-06-04

    A wind turbine comprising an electrical generator that includes a rotor assembly. A wind rotor that includes a wind rotor hub is directly coupled to the rotor assembly via a simplified connection. The wind rotor and generator rotor assembly are rotatably mounted on a central spindle via a bearing assembly. The wind rotor hub includes an opening having a diameter larger than the outside diameter of the central spindle adjacent the bearing assembly so as to allow access to the bearing assembly from a cavity inside the wind rotor hub. The spindle is attached to a turret supported by a tower. Each of the spindle, turret and tower has an interior cavity that permits personnel to traverse therethrough to the cavity of the wind rotor hub. The wind turbine further includes a frictional braking system for slowing, stopping or keeping stopped the rotation of the wind rotor and rotor assembly.

  4. An Experimental Evaluation of Blockage Corrections for Current Turbines

    Science.gov (United States)

    Ross, Hannah; Polagye, Brian

    2017-11-01

    Flow confinement has been shown to significantly alter the performance of turbines that extract power from water currents. These performance effects are related to the degree of constraint, defined by the ratio of turbine projected area to channel cross-sectional area. This quantity is referred to as the blockage ratio. Because it is often desirable to adjust experimental observations in water channels to unconfined conditions, analytical corrections for both wind and current turbines have been derived. These are generally based on linear momentum actuator disk theory but have been applied to turbines without experimental validation. This work tests multiple blockage corrections on performance and thrust data from a cross-flow turbine and porous plates (experimental analogues to actuator disks) collected in laboratory flumes at blockage ratios ranging between 10 and 35%. To isolate the effects of blockage, the Reynolds number, Froude number, and submergence depth were held constant while the channel width was varied. Corrected performance data are compared to performance in a towing tank at a blockage ratio of less than 5%. In addition to examining the accuracy of each correction, underlying assumptions are assessed to determine why some corrections perform better than others. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship Program under Grant No. DGE-1256082 and the Naval Facilities Engineering Command (NAVFAC).

  5. Melting of polydisperse hard disks

    NARCIS (Netherlands)

    Pronk, S.; Frenkel, D.

    2004-01-01

    The melting of a polydisperse hard-disk system is investigated by Monte Carlo simulations in the semigrand canonical ensemble. This is done in the context of possible continuous melting by a dislocation-unbinding mechanism, as an extension of the two-dimensional hard-disk melting problem. We find

  6. The Stability of Galaxy Disks

    NARCIS (Netherlands)

    Westfall, K. B.; Andersen, D. R.; Bershady, M. A.; Martinsson, T. P. K.; Swaters, R. A.; Verheijen, M. A. W.; Seigar, M.S.; Treuthardt, P.

    2014-01-01

    We calculate the stellar surface mass density (Σ*) and two-component (gas+stars) disk stability (QRW) for 25 late-type galaxies from the DiskMass Survey. These calculations are based on fits of a dynamical model to our ionized-gas and stellar kinematic data performed using a Markov Chain Monte Carlo

  7. Vibration of imperfect rotating disk

    Czech Academy of Sciences Publication Activity Database

    Půst, Ladislav; Pešek, Luděk

    2011-01-01

    Roč. 5, č. 2 (2011), s. 205-216 ISSN 1802-680X R&D Projects: GA ČR GA101/09/1166 Institutional research plan: CEZ:AV0Z20760514 Keywords : bladed disk * imperfect disk * travelling waves Subject RIV: BI - Acoustics http://www.kme.zcu.cz/acm/index.php/acm/article/view/86

  8. RINGED ACCRETION DISKS: EQUILIBRIUM CONFIGURATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Pugliese, D.; Stuchlík, Z., E-mail: d.pugliese.physics@gmail.com, E-mail: zdenek.stuchlik@physics.cz [Institute of Physics and Research Centre of Theoretical Physics and Astrophysics, Faculty of Philosophy and Science, Silesian University in Opava, Bezručovo náměstí 13, CZ-74601 Opava (Czech Republic)

    2015-12-15

    We investigate a model of a ringed accretion disk, made up by several rings rotating around a supermassive Kerr black hole attractor. Each toroid of the ringed disk is governed by the general relativity hydrodynamic Boyer condition of equilibrium configurations of rotating perfect fluids. Properties of the tori can then be determined by an appropriately defined effective potential reflecting the background Kerr geometry and the centrifugal effects. The ringed disks could be created in various regimes during the evolution of matter configurations around supermassive black holes. Therefore, both corotating and counterrotating rings have to be considered as being a constituent of the ringed disk. We provide constraints on the model parameters for the existence and stability of various ringed configurations and discuss occurrence of accretion onto the Kerr black hole and possible launching of jets from the ringed disk. We demonstrate that various ringed disks can be characterized by a maximum number of rings. We present also a perturbation analysis based on evolution of the oscillating components of the ringed disk. The dynamics of the unstable phases of the ringed disk evolution seems to be promising in relation to high-energy phenomena demonstrated in active galactic nuclei.

  9. Turbine Imaging Technology Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Moursund, Russell A.; Carlson, Thomas J.

    2004-12-31

    The goal of this project was to identify and evaluate imaging alternatives for observing the behavior of juvenile fish within an operating Kaplan turbine unit with a focus on methods to quantify fish injury mechanisms inside an operating turbine unit. Imaging methods are particularly needed to observe the approach and interaction of fish with turbine structural elements. This evaluation documents both the opportunities and constraints for observing juvenile fish at specific locations during turbine passage. The information may be used to acquire the scientific knowledge to make structural improvements and create opportunities for industry to modify turbines and improve fish passage conditions.

  10. Turbine related fish mortality

    International Nuclear Information System (INIS)

    Eicher, G.J.

    1993-01-01

    A literature review was conducted to assess the factors affecting turbine-related fish mortality. The mechanics of fish passage through a turbine is outlined, and various turbine related stresses are described, including pressure and shear effects, hydraulic head, turbine efficiency, and tailwater level. The methodologies used in determining the effects of fish passage are evaluated. The necessity of adequate controls in each test is noted. It is concluded that mortality is the result of several factors such as hardiness of study fish, fish size, concentrations of dissolved gases, and amounts of cavitation. Comparisons between Francis and Kaplan turbines indicate little difference in percent mortality. 27 refs., 5 figs

  11. Turbine Imaging Technology Assessment

    International Nuclear Information System (INIS)

    Moursund, Russell A.; Carlson, Thomas J.

    2004-01-01

    The goal of this project was to identify and evaluate imaging alternatives for observing the behavior of juvenile fish within an operating Kaplan turbine unit with a focus on methods to quantify fish injury mechanisms inside an operating turbine unit. Imaging methods are particularly needed to observe the approach and interaction of fish with turbine structural elements. This evaluation documents both the opportunities and constraints for observing juvenile fish at specific locations during turbine passage. The information may be used to acquire the scientific knowledge to make structural improvements and create opportunities for industry to modify turbines and improve fish passage conditions

  12. SPS RF Accelerating Cavity

    CERN Multimedia

    1979-01-01

    This picture shows one of the 2 new cavities installed in 1978-1979. The main RF-system of the SPS comprises four cavities: two of 20 m length and two of 16.5 m length. They are all installed in one long straight section (LSS 3). These cavities are of the travelling-wave type operating at a centre frequency of 200.2 MHz. They are wideband, filling time about 700 ns and untuned. The power amplifiers, using tetrodes are installed in a surface building 200 m from the cavities. Initially only two cavities were installed, a third cavity was installed in 1978 and a forth one in 1979. The number of power amplifiers was also increased: to the first 2 MW plant a second 2 MW plant was added and by end 1979 there were 8 500 kW units combined in pairs to feed each of the 4 cavities with up to about 1 MW RF power, resulting in a total accelerating voltage of about 8 MV. See also 7412016X, 7412017X, 7411048X

  13. Powder metallurgy Rene 95 rotating turbine engine parts, volume 2

    Science.gov (United States)

    Wilbers, L. G.; Redden, T. K.

    1981-01-01

    A Rene 95 alloy as-HIP high pressure turbine aft shaft in the CF6-50 engine and a HIP plus forged Rene 95 compressor disk in the CFM56 engine were tested. The CF6-50 engine test was conducted for 1000 C cycles and the CFM56 test for 2000 C cycles. Post test evaluation and analysis of the CF6-50 shaft and the CFM56 compressor disk included visual, fluorescent penetrant, and dimensional inspections. No defects or otherwise discrepant conditions were found. These parts were judged to have performed satisfactorily.

  14. Superconducting TESLA cavities

    Directory of Open Access Journals (Sweden)

    B. Aune

    2000-09-01

    Full Text Available The conceptional design of the proposed linear electron-positron collider TESLA is based on 9-cell 1.3 GHz superconducting niobium cavities with an accelerating gradient of E_{acc}≥25 MV/m at a quality factor Q_{0}≥5×10^{9}. The design goal for the cavities of the TESLA Test Facility (TTF linac was set to the more moderate value of E_{acc}≥15 MV/m. In a first series of 27 industrially produced TTF cavities the average gradient at Q_{0}=5×10^{9} was measured to be 20.1±6.2 MV/m, excluding a few cavities suffering from serious fabrication or material defects. In the second production of 24 TTF cavities, additional quality control measures were introduced, in particular, an eddy-current scan to eliminate niobium sheets with foreign material inclusions and stringent prescriptions for carrying out the electron-beam welds. The average gradient of these cavities at Q_{0}=5×10^{9} amounts to 25.0±3.2 MV/m with the exception of one cavity suffering from a weld defect. Hence only a moderate improvement in production and preparation techniques will be needed to meet the ambitious TESLA goal with an adequate safety margin. In this paper we present a detailed description of the design, fabrication, and preparation of the TESLA Test Facility cavities and their associated components and report on cavity performance in test cryostats and with electron beam in the TTF linac. The ongoing research and development towards higher gradients is briefly addressed.

  15. Cavity-enhanced spectroscopies

    CERN Document Server

    van Zee, Roger

    2003-01-01

    ""Cavity-Enhanced Spectroscopy"" discusses the use of optical resonators and lasers to make sensitive spectroscopic measurements. This volume is written by the researcchers who pioneered these methods. The book reviews both the theory and practice behind these spectroscopic tools and discusses the scientific discoveries uncovered by these techniques. It begins with a chapter on the use of optical resonators for frequency stabilization of lasers, which is followed by in-depth chapters discussing cavity ring-down spectroscopy, frequency-modulated, cavity-enhanced spectroscopy, intracavity spectr

  16. Tuned optical cavity magnetometer

    Science.gov (United States)

    Okandan, Murat; Schwindt, Peter

    2010-11-02

    An atomic magnetometer is disclosed which utilizes an optical cavity formed from a grating and a mirror, with a vapor cell containing an alkali metal vapor located inside the optical cavity. Lasers are used to magnetically polarize the alkali metal vapor and to probe the vapor and generate a diffracted laser beam which can be used to sense a magnetic field. Electrostatic actuators can be used in the magnetometer for positioning of the mirror, or for modulation thereof. Another optical cavity can also be formed from the mirror and a second grating for sensing, adjusting, or stabilizing the position of the mirror.

  17. Hydroforming of elliptical cavities

    Science.gov (United States)

    Singer, W.; Singer, X.; Jelezov, I.; Kneisel, P.

    2015-02-01

    Activities of the past several years in developing the technique of forming seamless (weldless) cavity cells by hydroforming are summarized. An overview of the technique developed at DESY for the fabrication of single cells and multicells of the TESLA cavity shape is given and the major rf results are presented. The forming is performed by expanding a seamless tube with internal water pressure while simultaneously swaging it axially. Prior to the expansion the tube is necked at the iris area and at the ends. Tube radii and axial displacements are computer controlled during the forming process in accordance with results of finite element method simulations for necking and expansion using the experimentally obtained strain-stress relationship of tube material. In cooperation with industry different methods of niobium seamless tube production have been explored. The most appropriate and successful method is a combination of spinning or deep drawing with flow forming. Several single-cell niobium cavities of the 1.3 GHz TESLA shape were produced by hydroforming. They reached accelerating gradients Eacc up to 35 MV /m after buffered chemical polishing (BCP) and up to 42 MV /m after electropolishing (EP). More recent work concentrated on fabrication and testing of multicell and nine-cell cavities. Several seamless two- and three-cell units were explored. Accelerating gradients Eacc of 30 - 35 MV /m were measured after BCP and Eacc up to 40 MV /m were reached after EP. Nine-cell niobium cavities combining three three-cell units were completed at the company E. Zanon. These cavities reached accelerating gradients of Eacc=30 - 35 MV /m . One cavity is successfully integrated in an XFEL cryomodule and is used in the operation of the FLASH linear accelerator at DESY. Additionally the fabrication of bimetallic single-cell and multicell NbCu cavities by hydroforming was successfully developed. Several NbCu clad single-cell and double-cell cavities of the TESLA shape have been

  18. Hydroforming of elliptical cavities

    Directory of Open Access Journals (Sweden)

    W. Singer

    2015-02-01

    Full Text Available Activities of the past several years in developing the technique of forming seamless (weldless cavity cells by hydroforming are summarized. An overview of the technique developed at DESY for the fabrication of single cells and multicells of the TESLA cavity shape is given and the major rf results are presented. The forming is performed by expanding a seamless tube with internal water pressure while simultaneously swaging it axially. Prior to the expansion the tube is necked at the iris area and at the ends. Tube radii and axial displacements are computer controlled during the forming process in accordance with results of finite element method simulations for necking and expansion using the experimentally obtained strain-stress relationship of tube material. In cooperation with industry different methods of niobium seamless tube production have been explored. The most appropriate and successful method is a combination of spinning or deep drawing with flow forming. Several single-cell niobium cavities of the 1.3 GHz TESLA shape were produced by hydroforming. They reached accelerating gradients E_{acc} up to 35  MV/m after buffered chemical polishing (BCP and up to 42  MV/m after electropolishing (EP. More recent work concentrated on fabrication and testing of multicell and nine-cell cavities. Several seamless two- and three-cell units were explored. Accelerating gradients E_{acc} of 30–35  MV/m were measured after BCP and E_{acc} up to 40  MV/m were reached after EP. Nine-cell niobium cavities combining three three-cell units were completed at the company E. Zanon. These cavities reached accelerating gradients of E_{acc}=30–35  MV/m. One cavity is successfully integrated in an XFEL cryomodule and is used in the operation of the FLASH linear accelerator at DESY. Additionally the fabrication of bimetallic single-cell and multicell NbCu cavities by hydroforming was successfully developed. Several NbCu clad single-cell and

  19. Micro-turbines

    International Nuclear Information System (INIS)

    Tashevski, Done

    2003-01-01

    In this paper a principle of micro-turbines operation, type of micro-turbines and their characteristics is presented. It is shown their usage in cogeneration and three generation application with the characteristics, the influence of more factors on micro-turbines operation as well as the possibility for application in Macedonia. The paper is result of the author's participation in the training program 'Micro-turbine technology' in Florida, USA. The characteristics of different types micro-turbines by several world producers are shown, with accent on US micro-turbines producers (Capstone, Elliott). By using the gathered Author's knowledge, contacts and the previous knowledge, conclusions and recommendations for implementation of micro-turbines in Macedonia are given. (Author)

  20. SPS accelerating cavity

    CERN Multimedia

    CERN PhotoLab

    1976-01-01

    The SPS started up with 2 accelerating cavities (each consisting of 5 tank sections) in LSS3. They have a 200 MHz travelling wave structure (see 7411032 and 7802190) and 750 kW of power is fed to each of the cavities from a 1 MW tetrode power amplifier, located in a surface building above, via a coaxial transmission line. Clemens Zettler, builder of the SPS RF system, is standing at the side of one of the cavities. In 1978 and 1979 another 2 cavities were added and entered service in 1980. These were part of the intensity improvement programme and served well for the new role of the SPS as proton-antiproton collider. See also 7411032, 8011289, 8104138, 8302397.

  1. Dental Sealants Prevent Cavities

    Science.gov (United States)

    ... Digital Press Kit Read the MMWR Science Clips Dental Sealants Prevent Cavities Effective protection for children Language: ... more use of sealants and reimbursement of services. Dental care providers can Apply sealants to children at ...

  2. Statistical electromagnetics: Complex cavities

    NARCIS (Netherlands)

    Naus, H.W.L.

    2008-01-01

    A selection of the literature on the statistical description of electromagnetic fields and complex cavities is concisely reviewed. Some essential concepts, for example, the application of the central limit theorem and the maximum entropy principle, are scrutinized. Implicit assumptions, biased

  3. accelerating cavity from LEP

    CERN Multimedia

    This is an accelerating cavity from LEP, with a layer of niobium on the inside. Operating at 4.2 degrees above absolute zero, the niobium is superconducting and carries an accelerating field of 6 million volts per metre with negligible losses. Each cavity has a surface of 6 m2. The niobium layer is only 1.2 microns thick, ten times thinner than a hair. Such a large area had never been coated to such a high accuracy. A speck of dust could ruin the performance of the whole cavity so the work had to be done in an extremely clean environment. These challenging requirements pushed European industry to new achievements. 256 of these cavities are now used in LEP to double the energy of the particle beams.

  4. HCO+ Detection of Dust-depleted Gas in the Inner Hole of the LkCa 15 Pre-transitional Disk

    NARCIS (Netherlands)

    Drabek-Maunder, E.; Mohanty, S.; Greaves, J.; Kamp, I.; Meijerink, R.; Spaans, M.; Thi, W. -F; Woitke, P.

    2016-01-01

    LkCa 15 is an extensively studied star in the Taurus region, known for its pre-transitional disk with a large inner cavity in the dust continuum and normal gas accretion rate. The most popular hypothesis to explain the LkCa 15 data invokes one or more planets to carve out the inner cavity, while gas

  5. Structural and thermal analysis of a solid-cooled, low energy booster, radio-frequency-cavity tuner at the Superconducting Super Collider

    International Nuclear Information System (INIS)

    Ranganathan, R.; Propp, A.; Dao, B.; Campbell, B.

    1993-04-01

    A three-dimensional heat conduction and structural model was developed to analyze and optimize the design of a solid-cooled low energy booster (LEB) radio-frequency (RF) cavity tuner concept. Consideration was given to three cooling options: (1) using beryllium oxide (BeO) disks, (2) using aluminum nitride (A1N) disks and (3) using neither BeO nor AlN disks. The results indicate that solid cooling is feasible from thermal and structural viewpoints if a minimum of two BeO disks or four AlN disks are used

  6. Structural and thermal analysis of a solid-cooled, low energy booster, radio-frequency-cavity tuner at the Superconducting Super Collider

    Energy Technology Data Exchange (ETDEWEB)

    Ranganathan, R.; Propp, A.; Dao, B.; Campbell, B.

    1993-04-01

    A three-dimensional heat conduction and structural model was developed to analyze and optimize the design of a solid-cooled low energy booster (LEB) radio-frequency (RF) cavity tuner concept. Consideration was given to three cooling options: (1) using beryllium oxide (BeO) disks, (2) using aluminum nitride (A1N) disks and (3) using neither BeO nor AlN disks. The results indicate that solid cooling is feasible from thermal and structural viewpoints if a minimum of two BeO disks or four AlN disks are used.

  7. Hybrid vertical cavity laser

    DEFF Research Database (Denmark)

    Chung, Il-Sug; Mørk, Jesper

    2010-01-01

    A new hybrid vertical cavity laser structure for silicon photonics is suggested and numerically investigated. It incorporates a silicon subwavelength grating as a mirror and a lateral output coupler to a silicon ridge waveguide.......A new hybrid vertical cavity laser structure for silicon photonics is suggested and numerically investigated. It incorporates a silicon subwavelength grating as a mirror and a lateral output coupler to a silicon ridge waveguide....

  8. Hydrogen Cyanide In Protoplanetary Disks

    Science.gov (United States)

    Walker, Ashley L.; Oberg, Karin; Cleeves, L. Ilsedore

    2018-01-01

    The chemistry behind star and planet formation is extremely complex and important in the formation of habitable planets. Life requires molecules containing carbon, oxygen, and importantly, nitrogen. Hydrogen cyanide, or HCN, one of the main interstellar nitrogen carriers, is extremely dangerous here on Earth. However, it could be used as a vital tool for tracking the chemistry of potentially habitable planets. As we get closer to identifying other habitable planets, we must understand the beginnings of how those planets are formed in the early protoplanetary disk. This project investigates HCN chemistry in different locations in the disk, and what this might mean for forming planets at different distances from the star. HCN is a chemically diverse molecule. It is connected to the formation for other more complex molecules and is commonly used as a nitrogen tracer. Using computational chemical models we look at how the HCN abundance changes at different locations. We use realistic and physically motivated conditions for the gas in the protoplanetary disk: temperature, density, and radiation (UV flux). We analyze the reaction network, formation, and destruction of HCN molecules in the disk environment. The disk environment informs us about stability of habitable planets that are created based on HCN molecules. We reviewed and compared the difference in the molecules with a variety of locations in the disk and ultimately giving us a better understanding on how we view protoplanetary disks.

  9. The Superconducting TESLA Cavities

    CERN Document Server

    Aune, B.; Bloess, D.; Bonin, B.; Bosotti, A.; Champion, M.; Crawford, C.; Deppe, G.; Dwersteg, B.; Edwards, D.A.; Edwards, H.T.; Ferrario, M.; Fouaidy, M.; Gall, P-D.; Gamp, A.; Gössel, A.; Graber, J.; Hubert, D.; Hüning, M.; Juillard, M.; Junquera, T.; Kaiser, H.; Kreps, G.; Kuchnir, M.; Lange, R.; Leenen, M.; Liepe, M.; Lilje, L.; Matheisen, A.; Möller, W-D.; Mosnier, A.; Padamsee, H.; Pagani, C.; Pekeler, M.; Peters, H-B.; Peters, O.; Proch, D.; Rehlich, K.; Reschke, D.; Safa, H.; Schilcher, T.; Schmüser, P.; Sekutowicz, J.; Simrock, S.; Singer, W.; Tigner, M.; Trines, D.; Twarowski, K.; Weichert, G.; Weisend, J.; Wojtkiewicz, J.; Wolff, S.; Zapfe, K.

    2000-01-01

    The conceptional design of the proposed linear electron-positron colliderTESLA is based on 9-cell 1.3 GHz superconducting niobium cavities with anaccelerating gradient of Eacc >= 25 MV/m at a quality factor Q0 > 5E+9. Thedesign goal for the cavities of the TESLA Test Facility (TTF) linac was set tothe more moderate value of Eacc >= 15 MV/m. In a first series of 27industrially produced TTF cavities the average gradient at Q0 = 5E+9 wasmeasured to be 20.1 +- 6.2 MV/m, excluding a few cavities suffering fromserious fabrication or material defects. In the second production of 24 TTFcavities additional quality control measures were introduced, in particular aneddy-current scan to eliminate niobium sheets with foreign material inclusionsand stringent prescriptions for carrying out the electron-beam welds. Theaverage gradient of these cavities at Q0 = 5E+9 amounts to 25.0 +- 3.2 MV/mwith the exception of one cavity suffering from a weld defect. Hence only amoderate improvement in production and preparation technique...

  10. Disk tides and accretion runaway

    Science.gov (United States)

    Ward, William R.; Hahn, Joseph M.

    1995-01-01

    It is suggested that tidal interaction of an accreting planetary embryo with the gaseous preplanetary disk may provide a mechanism to breach the so-called runaway limit during the formation of the giant planet cores. The disk tidal torque converts a would-be shepherding object into a 'predator,' which can continue to cannibalize the planetesimal disk. This is more likely to occur in the giant planet region than in the terrestrial zone, providing a natural cause for Jupiter to predate the inner planets and form within the O(10(exp 7) yr) lifetime of the nebula.

  11. 8-inch IBM floppy disk

    CERN Multimedia

    1971-01-01

    The 8-inch floppy disk was a magnetic storage disk for the data introduced commercially by IBM in 1971. It was designed by an IBM team as an inexpensive way to load data into the IBM System / 370. Plus it was a read-only bare disk containing 80 KB of data. The first read-write version was introduced in 1972 by Memorex and could contain 175 KB on 50 tracks (with 8 sectors per track). Other improvements have led to various coatings and increased capacities. Finally, it was surpassed by the mini diskette of 5.25 inches introduced in 1976.

  12. The Evolution of Spiral Disks

    Science.gov (United States)

    Bershady, Matthew A.; Andersen, David R.

    We report on aspects of an observational study to probe the mass assembly of large galaxy disks. In this contribution we focus on a new survey of integral-field Hα velocity-maps of nearby, face on disks. Preliminary results yield disk asymmetry amplitudes consistent with estimates based on the scatter in the local Tully-Fisher relation. We also show how the high quality of integral-field echelle spectroscopy enables determinations of kinematic inclinations to i ~20 °. This holds the promise that nearly-face-on galaxies can be included in the Tully-Fisher relation. Finally, we discuss the prospects for measuring dynamical asymmetries of distant galaxies.

  13. The Fortios disks revisited

    Directory of Open Access Journals (Sweden)

    António M. Monge Soares

    2017-07-01

    Full Text Available We have used EDXRF, Micro-PIXE and optical microscopy (metallographic analysis, complemented with SEM-EDS, to first determine the elemental content, and second, to identify the process used to join the components (disk, peripheral rod and tab of several Iron Age gold buttons. These have a very similar typology and were found at three archaeological sites in the South-Western part of the Iberian Peninsula. A set of 35 buttons from Castro dos Ratinhos (7, Outeiro da Cabeça (23 and Fortios (5 were analyzed and the results published in Trabajos de Prehistoria (Soares et al. 2010. Recently Perea et al. (2016 have published analyses of other 4 gold buttons from Fortios with the same purpose, but only using one technique, SEM-EDS. As they only analysed the rough surface layer, the results are neither effective nor reliable, taking into account the constraints associated with the technique, namely the small depth reached (< 2 ?m by the incident beam and, consequently, its sensitivity to the topography of the analyzed surface. Despite these constraints, they have accepted uncritically their results and, at the same time, question our own analyses and results and the interpretation we have made. Here we discuss the approach of Perea et al. in order to determine not only the elemental content of the Fortios gold buttons, but also to identify the joining process used in their manufacture.

  14. A new generation of wind turbines; Une nouvelle generation d'eoliennes

    Energy Technology Data Exchange (ETDEWEB)

    Nica, H. [Tesnic, Laval, PQ (Canada)

    2008-06-15

    Although homeowners have expressed a desire to use wind energy to supply their electricity needs, many technical barriers have stood in the way of installing wind turbines in urban settings. This was due in part to three-bladed vertical axis turbines, high technical costs, limited performances in urban settings and questionable aesthetics. Tesnic has considered these issues and proposed a completely different turbine that uses a different method for extracting energy from the wind. The first approved 3.6 kW model should appear by the end of 2009. This new turbine is based on the same principal of the steam turbine patented in 1913 by Nikola Tesla. Instead of having blades, the Tesla turbine used closely spaced parallel disks and was recognized as being very robust with a high efficiency rating. Tesnic's new wind powered turbine is a vertical axis turbine with a series of valves that directs the wind on a rotor assembly of disk space. A series of blades on its circumference redirects the wind through the assembly of discs and accelerates the rotation of the rotor. The turbine extracts the wind energy in several ways, including conventional drag and lift, adherence and the vortex effect. This gives a 50 per cent added value of efficiency compared to other wind powered turbines. The global market for small wind powered energy is in full expansion. It has been projected that small turbines with 1 kW capacity will be abundant by 2020. It was noted that for household wind powered energy, the market must consider issues of cost, low maintenance, noise pollution, visual aesthetics, durability and safety. Wind energy can also be used in several industries, including plastics, composites, light metals, textiles and electronics. 2 figs.

  15. Wind turbine operated sailboat

    Energy Technology Data Exchange (ETDEWEB)

    Hall, R.

    1990-07-31

    A wind powered boat is disclosed which incorporates a vertical axis rotary turbine. A shaft portion extends downwardly from the turbine to a water pump, with the boat being provided with a forwardly opening inlet and a rearwardly opening outlet from the water pump. When rotating, the turbine operates the pump by the shaft to draw in water through the inlet, thereby creating a low pressure area in front of the boat, and to force the water out through the outlet for propelling the boat. In a preferred embodiment, the boat has a catamaran construction or is a large ocean going vessel with enough width to provide a buffer to either side of the turbine, and the turbine is the Darrieus rotor type. The pump is a standard centrifugal type of pump. A self adjusting braking device for the turbine is also disclosed, which prevents over-rotation and is also capable of storing heat energy generated during braking. 4 figs.

  16. The swirl turbine

    International Nuclear Information System (INIS)

    Haluza, M; Pochylý, F; Rudolf, P

    2012-01-01

    In the article is introduced the new type of the turbine - swirl turbine. This turbine is based on opposite principle than Kaplan turbine. Euler equation is satisfied in the form gHη h = −u 2 v u2 . From this equation is seen, that inflow of liquid into the runner is without rotation and on the outflow is a rotation of liquid opposite of rotation of runner. This turbine is suitable for small head and large discharge. Some constructional variants of this turbine are introduced in the article and theoretical aspects regarding losses in the draft tube. The theory is followed by computational simulations in Fluent and experiments using laser Doppler anemometry.

  17. Wind Turbines Wake Aerodynamics

    DEFF Research Database (Denmark)

    Vermeer, L.; Sørensen, Jens Nørkær; Crespo, A.

    2003-01-01

    The aerodynamics of horizontal axis wind turbine wakes is studied. The contents is directed towards the physics of power extraction by wind turbines and reviews both the near and the far wake region. For the near wake, the survey is restricted to uniform, steady and parallel flow conditions......, thereby excluding wind shear, wind speed and rotor setting changes and yawed conditions. The emphasis is put on measurements in controlled conditions.For the far wake, the survey focusses on both single turbines and wind farm effects, and the experimental and numerical work are reviewed; the main interest...... is to study how the far wake decays downstream, in order to estimate the effect produced in downstream turbines.The article is further restricted to horizontal axis wind turbines and excludes all other types of turbines....

  18. Superconducting Wind Turbine Generators

    Directory of Open Access Journals (Sweden)

    Yunying Pan

    2016-08-01

    Full Text Available Wind energy is well known as a renewable energy because its clean and less polluted characteristic, which is the foundation of development modern wind electricity. To find more efficient wind turbine is the focus of scientists around the world. Compared from conventional wind turbines, superconducting wind turbine generators have advantages at zero resistance, smaller size and lighter weight. Superconducting wind turbine will inevitably become the main trends in this area. This paper intends to introduce the basic concept and principle of superconductivity, and compare form traditional wind turbine to obtain superiority, then to summary three proposed machine concept.While superconductivity have difficulty  in modern technology and we also have proposed some challenges in achieving superconducting wind turbine finally.

  19. Rotor Design for Diffuser Augmented Wind Turbines

    Directory of Open Access Journals (Sweden)

    Søren Hjort

    2015-09-01

    Full Text Available Diffuser augmented wind turbines (DAWTs can increase mass flow through the rotor substantially, but have often failed to fulfill expectations. We address high-performance diffusers, and investigate the design requirements for a DAWT rotor to efficiently convert the available energy to shaft energy. Several factors can induce wake stall scenarios causing significant energy loss. The causality between these stall mechanisms and earlier DAWT failures is discussed. First, a swirled actuator disk CFD code is validated through comparison with results from a far wake swirl corrected blade-element momentum (BEM model, and horizontal-axis wind turbine (HAWT reference results. Then, power efficiency versus thrust is computed with the swirled actuator disk (AD code for low and high values of tip-speed ratios (TSR, for different centerbodies, and for different spanwise rotor thrust loading distributions. Three different configurations are studied: The bare propeller HAWT, the classical DAWT, and the high-performance multi-element DAWT. In total nearly 400 high-resolution AD runs are generated. These results are presented and discussed. It is concluded that dedicated DAWT rotors can successfully convert the available energy to shaft energy, provided the identified design requirements for swirl and axial loading distributions are satisfied.

  20. Four-dimensional characterization of inflow to and wakes from a multi-MW turbine: overview of the Turbine Wake and Inflow Characterization Study (TWICS2011)

    Science.gov (United States)

    Lundquist, J. K.; Banta, R. M.; Pichugina, Y.; Brewer, A.; Alvarez, R. J.; Sandberg, S. P.; Kelley, N. D.; Aitken, M.; Clifton, A.; Mirocha, J. D.

    2011-12-01

    To support substantial deployment of renewably-generated electricity from the wind, critical information about the variability of wind turbine wakes in the real atmosphere from multi-MW turbines is required. The assessment of the velocity deficit and turbulence associated with industrial-scale turbines is a major issue for wind farm design, particularly with respect to the optimization of the spacing between turbines. The significant velocity deficit and turbulence generated by upstream turbines can reduce the power production and produce harmful vibrations in downstream turbines, which can lead to excess maintenance costs. The complexity of wake effects depends on many factors arising from both hardware (turbine size, rotor speed, and blade geometry, etc.) and from meteorological considerations such as wind velocity, gradients of wind across the turbine rotor disk, atmospheric stability, and atmospheric turbulence. To characterize the relationships between the meteorological inflow and turbine wakes, a collaborative field campaign was designed and carried out at the Department of Energy's National Wind Technology Center (NREL/NWTC) in south Boulder, Colorado, in spring 2011. This site often experiences channeled flow with a consistent wind direction, enabling robust statistics of wake velocity deficits and turbulence enhancements. Using both in situ and remote sensing instrumentation, measurements upwind and downwind of multi-megawatt wind turbine in complex terrain quantified the variability of wind turbine inflow and wakes from an industrial-scale turbine. The turbine of interest has a rated power of 2.3 MW, a rotor diameter of 100m, and a hub height of 80m. In addition to several meteorological towers, one extending to hub height (80m) and another extending above the top of the rotor disk (135m), a Triton mini-sodar and a Windcube lidar characterized the inflow to the turbine and the variability across the site. The centerpiece instrument of the TWICS campaign

  1. Flow in Pelton turbines

    OpenAIRE

    Furnes, Kjartan

    2013-01-01

    The flow in Pelton turbines is subsonic, turbulent, multiphase (water, air, and water vapor from cavitation), has high speeds, sharp gradients, free surface and dynamic boundary conditions. A static grid is unsuitable for modeling this mainly due to the turbine wheel and the liquid having a non-stationary relative motion.In recent times, significant progress in CFD simulation has been made, which also is relevant for Pelton turbines.Nevertheless, it is still common to perform costly model tes...

  2. Gravitational Instabilities in Circumstellar Disks

    Science.gov (United States)

    Kratter, Kaitlin; Lodato, Giuseppe

    2016-09-01

    Star and planet formation are the complex outcomes of gravitational collapse and angular momentum transport mediated by protostellar and protoplanetary disks. In this review, we focus on the role of gravitational instability in this process. We begin with a brief overview of the observational evidence for massive disks that might be subject to gravitational instability and then highlight the diverse ways in which the instability manifests itself in protostellar and protoplanetary disks: the generation of spiral arms, small-scale turbulence-like density fluctuations, and fragmentation of the disk itself. We present the analytic theory that describes the linear growth phase of the instability supplemented with a survey of numerical simulations that aim to capture the nonlinear evolution. We emphasize the role of thermodynamics and large-scale infall in controlling the outcome of the instability. Despite apparent controversies in the literature, we show a remarkable level of agreement between analytic predictions and numerical results. In the next part of our review, we focus on the astrophysical consequences of the instability. We show that the disks most likely to be gravitationally unstable are young and relatively massive compared with their host star, Md/M*≥0.1. They will develop quasi-stable spiral arms that process infall from the background cloud. Although instability is less likely at later times, once infall becomes less important, the manifestations of the instability are more varied. In this regime, the disk thermodynamics, often regulated by stellar irradiation, dictates the development and evolution of the instability. In some cases the instability may lead to fragmentation into bound companions. These companions are more likely to be brown dwarfs or stars than planetary mass objects. Finally, we highlight open questions related to the development of a turbulent cascade in thin disks and the role of mode-mode coupling in setting the maximum angular

  3. Bend testing for miniature disks

    International Nuclear Information System (INIS)

    Huang, F.H.; Hamilton, M.L.; Wire, G.L.

    1982-01-01

    A bend test was developed to obtain ductility measurements on a large number of alloy variants being irradiated in the form of miniature disks. Experimental results were shown to be in agreement with a theoretical analysis of the bend configuration. Disk specimens fabricated from the unstrained grip ends of previously tested tensile specimens were used for calibration purposes; bend ductilities and tensile ductilities were in good agreement. The criterion for estimating ductility was judged acceptable for screening purposes

  4. A method for detecting fungal contaminants in wall cavities.

    Science.gov (United States)

    Spurgeon, Joe C

    2003-01-01

    This article describes a practical method for detecting the presence of both fungal spores and culturable fungi in wall cavities. Culturable fungi were collected in 25 mm cassettes containing 0.8 microm mixed cellulose ester filters using aggressive sampling conditions. Both culturable fungi and fungal spores were collected in modified slotted-disk cassettes. The sample volume was 4 L. The filters were examined microscopically and dilution plated onto multiple culture media. Collecting airborne samples in filter cassettes was an effective method for assessing wall cavities for fungal contaminants, especially because this method allowed the sample to be analyzed by both microscopy and culture media. Assessment criteria were developed that allowed the sample results to be used to classify wall cavities as either uncontaminated or contaminated. As a criterion, wall cavities with concentrations of culturable fungi below the limit of detection (LOD) were classified as uncontaminated, whereas those cavities with detectable concentrations of culturable fungi were classified as contaminated. A total of 150 wall cavities was sampled as part of a field project. The concentrations of culturable fungi were below the LOD in 34% of the samples, whereas Aspergillus and/or Penicillium were the only fungal genera detected in 69% of the samples in which culturable fungi were detected. Spore counting resulted in the detection of Stachybotrys-like spores in 25% of the samples that were analyzed, whereas Stachybotrys chartarum colonies were only detected on 2% of malt extract agar plates and on 6% of corn meal agar plates.

  5. Apparatus and method for plasma processing of SRF cavities

    Science.gov (United States)

    Upadhyay, J.; Im, Do; Peshl, J.; Bašović, M.; Popović, S.; Valente-Feliciano, A.-M.; Phillips, L.; Vušković, L.

    2016-05-01

    An apparatus and a method are described for plasma etching of the inner surface of superconducting radio frequency (SRF) cavities. Accelerator SRF cavities are formed into a variable-diameter cylindrical structure made of bulk niobium, for resonant generation of the particle accelerating field. The etch rate non-uniformity due to depletion of the radicals has been overcome by the simultaneous movement of the gas flow inlet and the inner electrode. An effective shape of the inner electrode to reduce the plasma asymmetry for the coaxial cylindrical rf plasma reactor is determined and implemented in the cavity processing method. The processing was accomplished by moving axially the inner electrode and the gas flow inlet in a step-wise way to establish segmented plasma columns. The test structure was a pillbox cavity made of steel of similar dimension to the standard SRF cavity. This was adopted to experimentally verify the plasma surface reaction on cylindrical structures with variable diameter using the segmented plasma generation approach. The pill box cavity is filled with niobium ring- and disk-type samples and the etch rate of these samples was measured.

  6. Power generation from wind turbines in a solar chimney

    Energy Technology Data Exchange (ETDEWEB)

    Foote, Tudor [Graduate Student, Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, Jolley Hall, Campus Box 1185, One Brookings Drive, St. Louis, Missouri, 63130 (United States); Agarwal, Ramesh K. [William Palm Professor, Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, Jolley Hall, Campus Box 1185, One Brookings Drive, St. Louis, Missouri, 63130 (United States)

    2013-07-01

    Recent studies have shown that shrouded wind turbines can generate greater power compared to bare turbines. A solar chimney generates an upward draft of wind inside a tower and a shroud around the wind turbine. There are numerous empty silos on farms in the U.S. that can be converted to solar chimneys with minor modifications at modest cost. The objective of this study is to determine the potential of these silos/chimneys for generating wind power. The study is conducted through analytical/computational approach by employing the commercial Computational Fluid Dynamics (CFD) software. Computations are performed for five different geometric configurations consisting of a turbine, a cylindrical silo, and/or a venturi and/or a diffuser using the dimensions of typical silos and assuming Class 3 wind velocity. The incompressible Navier-Stokes equations with the Boussinesq approximation and a two equation realizable {kappa}-{epsilon} model are employed in the calculations, and the turbine is modeled as an actuator disk. The power coefficient (Cp) and generated power are calculated for the five cases. Consistent with recent literature, it was found that the silos with diffusers increase the Cp beyond Betz’s limit significantly and thus the generated power. It should be noted that Cp is calculated by normalizing it by the turbine area swept by the wind. This study shows the potential of using abandoned silos in the mid-west and other parts of the country for localized wind power generation.

  7. The Fabulous Four Debris Disks

    Science.gov (United States)

    Werner, Michael; Stapelfeldt, Karl

    2004-09-01

    This program is a comprehensive study of the four bright debris disks that were spatially resolved by IRAS: Beta Pictoris, Epsilon Eridani, Fomalhaut, and Vega. All SIRTF instruments and observing modes will be used. The program has three major objectives: (1) Study of the disk spatial structure from MIPS and IRAC imaging; (2) Study of the dust grain composition using the IRS and MIPS SED mode; and (3) companion searches using IRAC. The data from this program should lead to a detailed understanding of these four systems, and will provide a foundation for understanding all of the debris disks to be studied with SIRTF. Images and spectra will be compared with models for disk structure and dust properties. Dynamical features indicative of substellar companions' effects on the disks will be searched for. This program will require supporting observations of PSF stars, some of which have been included explicitly. In the majority of cases, the spectral observations require a preferred orientation to align the slits along the disk position angles. Detector saturation issues are still being worked for this program, and will lead to AOR modifications in subsequent submissions. The results from this program will be analyzed collaboratively by the IRAC, IRS, and MIPS teams and by general GTOs Jura and Werner.

  8. Wind Turbine Technologies

    DEFF Research Database (Denmark)

    Hansen, Anca Daniela

    2017-01-01

    , and with or without gearboxes, using the latest in power electronics, aerodynamics, and mechanical drive train designs [4]. The main differences between all wind turbine concepts developed over the years, concern their electrical design and control. Today, the wind turbines on the market mix and match a variety......, the design of wind turbines has changed from being convention driven to being optimized driven within the operating regime and market environment. Wind turbine designs have progressed from fixed speed, passive controlled and with drive trains with gearboxes, to become variable speed, active controlled......,6] and to implement modern control system strategies....

  9. A Study of Inner Disk Gas around Young Stars in the Lupus Complex

    Science.gov (United States)

    Arulanantham, Nicole Annemarie; France, Kevin; Hoadley, Keri

    2018-06-01

    We present a study of molecular hydrogen at the surfaces of the disks around five young stars in the Lupus complex: RY Lupi, RU Lupi, MY Lupi, Sz 68, and TYC 7851. Each system was observed with the Cosmic Origins Spectrograph (COS) onboard the Hubble Space Telescope (HST), and we detect a population of fluorescent H2 in all five sources. The temperatures required for LyA fluorescence to proceed (T ~ 1500-2500 K) place the gas within ~15 AU of the central stars. We have used these features to extract the radial distribution of H2 in the inner disk, where planet formation may already be taking place. The objects presented here have very different outer disk morphologies, as seen by ALMA via 890 micron dust continuum emission, ranging from full disks with no signs of cavities to systems with large regions that are clearly depleted (e.g. TYC 7851, with a cavity extending to 75 and 60 AU in dust and gas, respectively). Our results are interpreted in conjunction with sub-mm data from the five systems in an effort to piece together a more complete picture of the overall disk structure. We have previously applied this multi-wavelength approach to RY Lupi, including 4.7 micron IR-CO emission in our analysis. These IR-CO and UV-H2 observations were combined with 10 micron silicate emission, the 890 micron dust continuum, and 1.3 mm CO observations from the literature to infer a gapped structure in the inner disk. This single system has served as a testing ground for the larger Lupus complex sample, which we compare here to examine any trends between the outer disk morphology and inner disk gas distributions.

  10. Metasurface external cavity laser

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Luyao, E-mail: luyaoxu.ee@ucla.edu; Curwen, Christopher A.; Williams, Benjamin S. [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); California NanoSystems Institute, University of California, Los Angeles, California 90095 (United States); Hon, Philip W. C.; Itoh, Tatsuo [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); Chen, Qi-Sheng [Northrop Grumman Aerospace Systems, Redondo Beach, California 90278 (United States)

    2015-11-30

    A vertical-external-cavity surface-emitting-laser is demonstrated in the terahertz range, which is based upon an amplifying metasurface reflector composed of a sub-wavelength array of antenna-coupled quantum-cascade sub-cavities. Lasing is possible when the metasurface reflector is placed into a low-loss external cavity such that the external cavity—not the sub-cavities—determines the beam properties. A near-Gaussian beam of 4.3° × 5.1° divergence is observed and an output power level >5 mW is achieved. The polarized response of the metasurface allows the use of a wire-grid polarizer as an output coupler that is continuously tunable.

  11. Annular array technology for nondestructive turbine inspection. Final report

    International Nuclear Information System (INIS)

    Light, G.M.

    1986-05-01

    The Electric Power Research Institute (EPRI) funded Southwest Research Institute (SwRI) to fabricate and functionally test phased array transducers and an electronic control system with the intent of evaluating the phased array technology for use in the inspection of turbine disks. During this program a 13-element annular array and associated phased array electronics were fabricated and tested and the results of the tests compared to those predicted by theory. The prototype system performed well within the expected limits, and EPRI funded further work to fabricate and test a production unit. The production system consisted of a 25-element annular array and a 25-channel electronics system that had both pulser and receiver delay circuitry. In addition, during the program it was determined that miniaturized hybrid pulser/preamps would be needed to allow the phased array to work over distances exceeding 9.1 meters (30 feet) from the electronics. A circuit developed by SwRI was utilized and found to produce good pulsing capability that did not suffer from impedance mismatch. EPRI also funded (under a separate contract) the fabrication of a small scale static turbine test bed and a full scale dynamic test bed that contained full scale turbine geometries. These test beds were fabricated to enable the production phased array system to be evaluated on turbine disk surfaces. 26 figs

  12. Earth-ionosphere cavity

    International Nuclear Information System (INIS)

    Tran, A.; Polk, C.

    1976-01-01

    To analyze ELF wave propagation in the earth-ionosphere cavity, a flat earth approximation may be derived from the exact equations, which are applicable to the spherical cavity, by introducing a second-order or Debye approximation for the spherical Hankel functions. In the frequency range 3 to 30 Hz, however, the assumed conditions for the Debye approximation are not satisfied. For this reason an exact evaluation of the spherical Hankel functions is used to study the effects of the flat earth approximation on various propagation and resonance parameters. By comparing the resonance equation for a spherical cavity with its flat earth counterpart and by assuming that the surface impedance Z/sub i/ at the upper cavity boundary is known, the relation between the eigenvalue ν and S/sub v/, the sine of the complex angle of incidence at the lower ionosphere boundary, is established as ν(ν + 1) = (kaS/sub v/) 2 . It is also shown that the approximation ν(ν + 1) approximately equals (ν + 1/2) 2 which was used by some authors is not adequate below 30 Hz. Numerical results for both spherical and planar stratification show that (1) planar stratification is adequate for the computation of the lowest three ELF resonance frequencies to within 0.1 Hz; (2) planar stratification will lead to errors in cavity Q and wave attenuation which increase with frequency; (3) computation of resonance frequencies to within 0.1 Hz requires the extension of the lower boundary of the ionosphere to a height where the ratio of conduction current to displacement current, (sigma/ωepsilon 0 ), is less than 0.3; (4) atmospheric conductivity should be considered down to ground level in computing cavity Q and wave attenuation

  13. Covering and piercing disks with two centers

    KAUST Repository

    Ahn, Heekap; Kim, Sangsub; Knauer, Christian; Schlipf, Lena; Shin, Chansu; Vigneron, Antoine E.

    2013-01-01

    We give exact and approximation algorithms for two-center problems when the input is a set D of disks in the plane. We first study the problem of finding two smallest congruent disks such that each disk in D intersects one of these two disks. Then we study the problem of covering the set D by two smallest congruent disks. © 2012 Elsevier B.V.

  14. Covering and piercing disks with two centers

    KAUST Repository

    Ahn, Heekap

    2013-04-01

    We give exact and approximation algorithms for two-center problems when the input is a set D of disks in the plane. We first study the problem of finding two smallest congruent disks such that each disk in D intersects one of these two disks. Then we study the problem of covering the set D by two smallest congruent disks. © 2012 Elsevier B.V.

  15. Covering and piercing disks with two centers

    KAUST Repository

    Ahn, Heekap; Kim, Sangsub; Knauer, Christian; Schlipf, Lena; Shin, Chansu; Vigneron, Antoine E.

    2011-01-01

    We consider new versions of the two-center problem where the input consists of a set D of disks in the plane. We first study the problem of finding two smallest congruent disks such that each disk in intersects one of these two disks. Then we study the problem of covering the set D by two smallest congruent disks. We give exact and approximation algorithms for these versions. © 2011 Springer-Verlag.

  16. Materials for superconducting cavities

    International Nuclear Information System (INIS)

    Bonin, B.

    1996-01-01

    The ideal material for superconducting cavities should exhibit a high critical temperature, a high critical field, and, above all, a low surface resistance. Unfortunately, these requirements can be conflicting and a compromise has to be found. To date, most superconducting cavities for accelerators are made of niobium. The reasons for this choice are discussed. Thin films of other materials such as NbN, Nb 3 Sn, or even YBCO compounds can also be envisaged and are presently investigated in various laboratories. It is shown that their success will depend critically on the crystalline perfection of these films. (author)

  17. Microstructure Modeling of 3rd Generation Disk Alloy

    Science.gov (United States)

    Jou, Herng-Jeng

    2008-01-01

    The objective of this initiative, funded by NASA's Aviation Safety Program, is to model, validate, and predict, with high fidelity, the microstructural evolution of third-generation high-refractory Ni-based disc superalloys during heat treating and service conditions. This initiative is a natural extension of the DARPA-AIM (Accelerated Insertion of Materials) initiative with GE/Pratt-Whitney and with other process simulation tools. Strong collaboration with the NASA Glenn Research Center (GRC) is a key component of this initiative and the focus of this program is on industrially relevant disk alloys and heat treatment processes identified by GRC. Employing QuesTek s Computational Materials Dynamics technology and PrecipiCalc precipitation simulator, physics-based models are being used to achieve high predictive accuracy and precision. Combining these models with experimental data and probabilistic analysis, "virtual alloy design" can be performed. The predicted microstructures can be optimized to promote desirable features and concurrently eliminate nondesirable phases that can limit the reliability and durability of the alloys. The well-calibrated and well-integrated software tools that are being applied under the proposed program will help gas turbine disk alloy manufacturers, processing facilities, and NASA, to efficiently and effectively improve the performance of current and future disk materials.

  18. Experimental investigation of cavity flows

    Energy Technology Data Exchange (ETDEWEB)

    Loeland, Tore

    1999-12-31

    This thesis uses LDV (Laser Doppler Velocimetry), PIV (Particle Image Velocimetry) and Laser Sheet flow Visualisation to study flow inside three different cavity configurations. For sloping cavities, the vortex structure inside the cavities is found to depend upon the flow direction past the cavity. The shape of the downstream corner is a key factor in destroying the boundary layer flow entering the cavity. The experimental results agree well with numerical simulations of the same geometrical configurations. The results of the investigations are used to find the influence of the cavity flow on the accuracy of the ultrasonic flowmeter. A method to compensate for the cavity velocities is suggested. It is found that the relative deviation caused by the cavity velocities depend linearly on the pipe flow. It appears that the flow inside the cavities should not be neglected as done in the draft for the ISO technical report on ultrasonic flowmeters. 58 refs., 147 figs., 2 tabs.

  19. Experimental investigation of cavity flows

    Energy Technology Data Exchange (ETDEWEB)

    Loeland, Tore

    1998-12-31

    This thesis uses LDV (Laser Doppler Velocimetry), PIV (Particle Image Velocimetry) and Laser Sheet flow Visualisation to study flow inside three different cavity configurations. For sloping cavities, the vortex structure inside the cavities is found to depend upon the flow direction past the cavity. The shape of the downstream corner is a key factor in destroying the boundary layer flow entering the cavity. The experimental results agree well with numerical simulations of the same geometrical configurations. The results of the investigations are used to find the influence of the cavity flow on the accuracy of the ultrasonic flowmeter. A method to compensate for the cavity velocities is suggested. It is found that the relative deviation caused by the cavity velocities depend linearly on the pipe flow. It appears that the flow inside the cavities should not be neglected as done in the draft for the ISO technical report on ultrasonic flowmeters. 58 refs., 147 figs., 2 tabs.

  20. Site-specific Pt deposition and etching on electrically and thermally isolated SiO2 micro-disk surfaces

    International Nuclear Information System (INIS)

    Saraf, Laxmikant V

    2010-01-01

    Electrically and thermally isolated surfaces are crucial for improving the detection sensitivity of microelectronic sensors. The site-specific in situ growth of Pt nano-rods on thermally and electrically isolated SiO 2 micro-disks using wet chemical etching and a focused ion/electron dual beam (FIB-SEM) is demonstrated. Fabrication of an array of micro-cavities on top of a micro-disk is also demonstrated. The FIB source is utilized to fabricate through-holes in the micro-disks. Due to the amorphous nature of SiO 2 micro-disks, the Ga implantation possibly modifies through-hole sidewall surface chemistry rather than affecting its transport properties. Some sensor design concepts based on micro-fabrication of SiO 2 micro-disks utilizing thermally and electrically isolated surfaces are discussed from the viewpoint of applications in photonics and bio-sensing.

  1. Guide to hydro turbines

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    This listing is a guide to turbines for hydroelectric projects of independent energy projects. The listing is in directory format and includes the supplier's name, the name of the supplier's contact, address, telephone and FAX numbers and a description of the company and the types of turbines, services and expertise available for energy projects. The listing is international in scope

  2. Improvement of turbine materials

    International Nuclear Information System (INIS)

    Jakobeit, W.; Pfeifer, J.P.

    1982-01-01

    Materials for turbine blades and rotors are discussed with a view to the following subjects: Long period creep behaviour, gas/metal reactions, fatigue behaviour in long-term and creep strength testing, fracture mechanics testing, creep/fatigue interactions, development of a turbine blade of TZM, jointing of TZM, decontamination. (orig./IHOE) [de

  3. Investigation of damping potential of strip damper on a real turbine blade

    NARCIS (Netherlands)

    Afzal, M.; Lopez Arteaga, I.; Kari, L.; Kharyton, V.

    2016-01-01

    This paper investigates the damping potential of strip dampers on a real turbine bladed disk. A 3D numerical friction contact model is used to compute the contact forces by means of the Alternate Frequency Time domain method. The Jacobian matrix required during the iterative solution is computed in

  4. Noise from wind turbines

    International Nuclear Information System (INIS)

    Andersen, B.; Larsen, P.

    1993-01-01

    Denmark has 3200 wind turbines with an installed maximum capacity of 418MW. The most important Danish research projects into wind turbine noise and the main results are listed. These date from 1983. Two comprehensive studies are currently in progress. The first is an analytical and empirical investigation of aerodynamic noise from wind turbine rotors and has so far dealt mainly with tip noise. The measurement method, using a hard board mounted microphone on the ground near the turbine, is described. Four different tip designs have been tested. Some examples of reference sound power level spectra for three of the designs are presented. During the past two years a computerbased data acquisition system has been used for real-time determination of sound power levels. The second study, which has just commenced, is on annoyance from wind turbine noise. It will include noise measurements, masking calculations and a social survey on the perceived nuisance. (UK)

  5. Graphene in turbine blades

    Science.gov (United States)

    Das, D. K.; Swain, P. K.; Sahoo, S.

    2016-07-01

    Graphene, the two-dimensional (2D) nanomaterial, draws interest of several researchers due to its many superior properties. It has extensive applications in numerous fields. A turbine is a hydraulic machine which extracts energy from a fluid and converts it into useful work. Recently, Gudukeya and Madanhire have tried to increase the efficiency of Pelton turbine. Beucher et al. have also tried the same by reducing friction between fluid and turbine blades. In this paper, we study the advantages of using graphene as a coating on Pelton turbine blades. It is found that the efficiency of turbines increases, running and maintenance cost is reduced with more power output. By the application of graphene in pipes, cavitation will be reduced, durability of pipes will increase, operation and maintenance cost of water power plants will be less.

  6. Confined surface plasmon sensors based on strongly coupled disk-in-volcano arrays.

    Science.gov (United States)

    Ai, Bin; Wang, Limin; Möhwald, Helmuth; Yu, Ye; Zhang, Gang

    2015-02-14

    Disk-in-volcano arrays are reported to greatly enhance the sensing performance due to strong coupling in the nanogaps between the nanovolcanos and nanodisks. The designed structure, which is composed of a nanovolcano array film and a disk in each cavity, is fabricated by a simple and efficient colloidal lithography method. By tuning structural parameters, the disk-in-volcano arrays show greatly enhanced resonances in the nanogaps formed by the disks and the inner wall of the volcanos. Therefore they respond to the surrounding environment with a sensitivity as high as 977 nm per RIU and with excellent linear dependence on the refraction index. Moreover, through mastering the fabrication process, biological sensing can be easily confined to the cavities of the nanovolcanos. The local responsivity has the advantages of maximum surface plasmon energy density in the nanogaps, reducing the sensing background and saving expensive reagents. The disk-in-volcano arrays also possess great potential in applications of optical and electrical trapping and single-molecule analysis, because they enable establishment of electric fields across the gaps.

  7. Multipactors in klystron cavities

    International Nuclear Information System (INIS)

    Hayashi, Kazutaka; Iyeki, Hiroshi; Kikunaga, Toshiyuki.

    1993-01-01

    A multipactor phenomenon in a klystron causes gain shortage or instability problem. Some tests using a prototype klystron input cavity revealed the microwave discharges in vacuum with magnetic field. The test results and the methods to avoid multipactors are discussed in this paper. (author)

  8. What's a Cavity?

    Science.gov (United States)

    ... and deeper over time. Cavities are also called dental caries (say: KARE-eez), and if you have a ... made up mostly of the germs that cause tooth decay. The bacteria in your mouth make acids and when plaque clings to your teeth, the acids can eat away at the outermost ...

  9. Vertical cavity laser

    DEFF Research Database (Denmark)

    2016-01-01

    The present invention provides a vertical cavity laser comprising a grating layer comprising an in-plane grating, the grating layer having a first side and having a second side opposite the first side and comprising a contiguous core grating region having a grating structure, wherein an index...

  10. Oral cavity and jaw

    International Nuclear Information System (INIS)

    Solntsev, A.M.; Koval', G.Yu.

    1984-01-01

    Radioanatome of oral cavity and jaw is described. Diseases of the teeth, jaw, large salivary glands, temporo-mandibular articulation are considered. Roentgenograms of oral cacity and jaw of healthy people are presented and analyzed as well as roentgenograms in the above-mentioned diseases

  11. Niobium superconducting cavity

    CERN Multimedia

    CERN PhotoLab

    1980-01-01

    This 5-cell superconducting cavity, made from bulk-Nb, stems from the period of general studies, not all directed towards direct use at LEP. This one is dimensioned for 1.5 GHz, the frequency used at CEBAF and also studied at Saclay (LEP RF was 352.2 MHz). See also 7908227, 8007354, 8209255, 8210054, 8312339.

  12. Superconducting elliptical cavities

    CERN Document Server

    Sekutowicz, J K

    2011-01-01

    We give a brief overview of the history, state of the art, and future for elliptical superconducting cavities. Principles of the cell shape optimization, criteria for multi-cell structures design, HOM damping schemes and other features are discussed along with examples of superconducting structures for various applications.

  13. Additive Manufactured Superconducting Cavities

    Science.gov (United States)

    Holland, Eric; Rosen, Yaniv; Woolleet, Nathan; Materise, Nicholas; Voisin, Thomas; Wang, Morris; Mireles, Jorge; Carosi, Gianpaolo; Dubois, Jonathan

    Superconducting radio frequency cavities provide an ultra-low dissipative environment, which has enabled fundamental investigations in quantum mechanics, materials properties, and the search for new particles in and beyond the standard model. However, resonator designs are constrained by limitations in conventional machining techniques. For example, current through a seam is a limiting factor in performance for many waveguide cavities. Development of highly reproducible methods for metallic parts through additive manufacturing, referred to colloquially as 3D printing\\x9D, opens the possibility for novel cavity designs which cannot be implemented through conventional methods. We present preliminary investigations of superconducting cavities made through a selective laser melting process, which compacts a granular powder via a high-power laser according to a digitally defined geometry. Initial work suggests that assuming a loss model and numerically optimizing a geometry to minimize dissipation results in modest improvements in device performance. Furthermore, a subset of titanium alloys, particularly, a titanium, aluminum, vanadium alloy (Ti - 6Al - 4V) exhibits properties indicative of a high kinetic inductance material. This work is supported by LDRD 16-SI-004.

  14. Cavity Nesting Birds

    Science.gov (United States)

    Virgil E. Scott; Keith E. Evans; David R. Patton; Charles P. Stone

    1977-01-01

    Many species of cavity-nesting birds have declined because of habitat reduction. In the eastern United States, where primeval forests are gone, purple martins depend almost entirely on man-made nesting structures (Allen and Nice 1952). The hole-nesting population of peregrine falcons disappeared with the felling of the giant trees upon which they depended (Hickey and...

  15. LEP superconducting cavity

    CERN Multimedia

    1995-01-01

    Engineers work in a clean room on one of the superconducting cavities for the upgrade to the LEP accelerator, known as LEP-2. The use of superconductors allow higher electric fields to be produced so that higher beam energies can be reached.

  16. Open microwave cavities

    Czech Academy of Sciences Publication Activity Database

    Šeba, Petr; Rotter, I.; Mueller, M.; Persson, C.; Pichugin, Konstantin N.

    2001-01-01

    Roč. 9, - (2001), s. 484-487 ISSN 1386-9477 Institutional research plan: CEZ:A02/98:Z1-010-914 Keywords : microwave cavity * resonances Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.009, year: 2001

  17. Filling a Conical Cavity

    Science.gov (United States)

    Nye, Kyle; Eslam-Panah, Azar

    2016-11-01

    Root canal treatment involves the removal of infected tissue inside the tooth's canal system and filling the space with a dense sealing agent to prevent further infection. A good root canal treatment happens when the canals are filled homogeneously and tightly down to the root apex. Such a tooth is able to provide valuable service for an entire lifetime. However, there are some examples of poorly performed root canals where the anterior and posterior routes are not filled completely. Small packets of air can be trapped in narrow access cavities when restoring with resin composites. Such teeth can cause trouble even after many years and lead the conditions like acute bone infection or abscesses. In this study, the filling of dead-end conical cavities with various liquids is reported. The first case studies included conical cavity models with different angles and lengths to visualize the filling process. In this investigation, the rate and completeness at which a variety of liquids fill the cavity were observed to find ideal conditions for the process. Then, a 3D printed model of the scaled representation of a molar with prepared post spaces was used to simulate the root canal treatment. The results of this study can be used to gain a better understanding of the restoration for endodontically treated teeth.

  18. Ultrafast disk lasers and amplifiers

    Science.gov (United States)

    Sutter, Dirk H.; Kleinbauer, Jochen; Bauer, Dominik; Wolf, Martin; Tan, Chuong; Gebs, Raphael; Budnicki, Aleksander; Wagenblast, Philipp; Weiler, Sascha

    2012-03-01

    Disk lasers with multi-kW continuous wave (CW) output power are widely used in manufacturing, primarily for cutting and welding applications, notably in the automotive industry. The ytterbium disk technology combines high power (average and/or peak power), excellent beam quality, high efficiency, and high reliability with low investment and operating costs. Fundamental mode picosecond disk lasers are well established in micro machining at high throughput and perfect precision. Following the world's first market introduction of industrial grade 50 W picosecond lasers (TruMicro 5050) at the Photonics West 2008, the second generation of the TruMicro series 5000 now provides twice the average power (100 W at 1030 nm, or 60 W frequency doubled, green output) at a significantly reduced footprint. Mode-locked disk oscillators achieve by far the highest average power of any unamplified lasers, significantly exceeding the 100 W level in laboratory set-ups. With robust long resonators their multi-microjoule pulse energies begin to compete with typical ultrafast amplifiers. In addition, significant interest in disk technology has recently come from the extreme light laser community, aiming for ultra-high peak powers of petawatts and beyond.

  19. The Parameters Affect on Power Coefficient Vertical Axis Wind Turbine

    Directory of Open Access Journals (Sweden)

    Ahmed Y. Qasim

    2012-04-01

    Full Text Available ABSTRACT: This study describes the design of a special type of vertical axis rotor wind turbine with moveable vertically positioned vanes. The novel design increases the torque in the left side of the wind turbine by increasing the drag coefficient. It also reduces the negative torque of the frame which rotates contrary to the wind in the other side. Two different types of models, having different vane shapes (flat vane and cavity shaped vane, were fabricated. Each type consisted of two models with varying number of frames (three and four frames. The models were tested in a wind tunnel with variable wind speed in order to understand the effect of shape, weight, and number of frames on the power coefficient of the wind turbine. ABSTRAK: Di dalam kajian ini, rotor turbin angin berpaksi vertikel sebagai rangka khusus telah direkabentuk dengan lokasi vertikel mudahalih oleh bilah kipas. Rekabentuk ini meningkatkan tork di bahagian kiri turbin angin dengan meningkatkan pekali seretan dan mengurangkan tork negatif rangka yang berputar berlawanan dengan angin pada bahagian lain. Dua jenis model berbentuk berlainan telah difabrikasi (bilah kipas rata dan bilah kipas berbentuk kaviti, dengan setiap jenis mempunyai dua model dengan bilangan rangka yang berlainan (berangka tiga dan berangka empat. Model-model telah diuji di dalam terowong angin dengan kelajuan angin yang berbeza bagi mendapatkan kesan rekabentuk, berat dan bilangan rangka ke atas pekali kuasa.KEYWORDS: design; wind turbine; drag coefficient; vane

  20. A New Energy-Critical Plane Damage Parameter for Multiaxial Fatigue Life Prediction of Turbine Blades

    Directory of Open Access Journals (Sweden)

    Zheng-Yong Yu

    2017-05-01

    Full Text Available As one of fracture critical components of an aircraft engine, accurate life prediction of a turbine blade to disk attachment is significant for ensuring the engine structural integrity and reliability. Fatigue failure of a turbine blade is often caused under multiaxial cyclic loadings at high temperatures. In this paper, considering different failure types, a new energy-critical plane damage parameter is proposed for multiaxial fatigue life prediction, and no extra fitted material constants will be needed for practical applications. Moreover, three multiaxial models with maximum damage parameters on the critical plane are evaluated under tension-compression and tension-torsion loadings. Experimental data of GH4169 under proportional and non-proportional fatigue loadings and a case study of a turbine disk-blade contact system are introduced for model validation. Results show that model predictions by Wang-Brown (WB and Fatemi-Socie (FS models with maximum damage parameters are conservative and acceptable. For the turbine disk-blade contact system, both of the proposed damage parameters and Smith-Watson-Topper (SWT model show reasonably acceptable correlations with its field number of flight cycles. However, life estimations of the turbine blade reveal that the definition of the maximum damage parameter is not reasonable for the WB model but effective for both the FS and SWT models.

  1. CT recognition of lateral lumbar disk herniation

    International Nuclear Information System (INIS)

    Williams, A.L.; Haughton, V.M.; Daniels, D.L.; Thornton, R.S.

    1982-01-01

    Although computed tomography (CT) has been shown to be useful in diagnosing posterolateral and central lumbar disk herniations, its effectiveness in demonstrating lateral herniated disks has not been emphasized. The myelographic recognition of those herniations may be difficult because root sheaths or dural sacs may not be deformed. A total of 274 CT scans interpreted as showing lumbar disk herniation was reviewed. Fourteen (5%) showed a lateral disk herniation. The CT features of a lateral herniated disk included: (1) focal protrusion of the disk margin within or lateral to the intervertebral foramen: (2) displacement of epidural fat within the intervertebral foramen; (3) absence of dural sac deformity; and (4) soft-tissue mass within or lateral to the intervertebral foramen. Because it can image the disk margin and free disk fragments irrespective of dural sac or root sheath deformity, CT may be more effective than myelography for demonstrating the presence and extent of lateral disk herniation

  2. Implosion of the small cavity and large cavity cannonball targets

    International Nuclear Information System (INIS)

    Nishihara, Katsunobu; Yamanaka, Chiyoe.

    1984-01-01

    Recent results of cannonball target implosion research are briefly reviewed with theoretical predictions for GEKKO XII experiments. The cannonball targets are classified into two types according to the cavity size ; small cavity and large cavity. The compression mechanisms of the two types are discussed. (author)

  3. Turbine airfoil having near-wall cooling insert

    Science.gov (United States)

    Martin, Jr., Nicholas F.; Wiebe, David J.

    2017-09-12

    A turbine airfoil is provided with at least one insert positioned in a cavity in an airfoil interior. The insert extends along a span-wise extent of the turbine airfoil and includes first and second opposite faces. A first near-wall cooling channel is defined between the first face and a pressure sidewall of an airfoil outer wall. A second near-wall cooling channel is defined between the second face and a suction sidewall of the airfoil outer wall. The insert is configured to occupy an inactive volume in the airfoil interior so as to displace a coolant flow in the cavity toward the first and second near-wall cooling channels. A locating feature engages the insert with the outer wall for supporting the insert in position. The locating feature is configured to control flow of the coolant through the first or second near-wall cooling channel.

  4. Dust in protoplanetary disks: observations*

    Directory of Open Access Journals (Sweden)

    Waters L.B.F.M.

    2015-01-01

    Full Text Available Solid particles, usually referred to as dust, are a crucial component of interstellar matter and of planet forming disks surrounding young stars. Despite the relatively small mass fraction of ≈1% (in the solar neighborhood of our galaxy; this number may differ substantially in other galaxies that interstellar grains represent of the total mass budget of interstellar matter, dust grains play an important role in the physics and chemistry of interstellar matter. This is because of the opacity dust grains at short (optical, UV wavelengths, and the surface they provide for chemical reactions. In addition, dust grains play a pivotal role in the planet formation process: in the core accretion model of planet formation, the growth of dust grains from the microscopic size range to large, cm-sized or larger grains is the first step in planet formation. Not only the grain size distribution is affected by planet formation. Chemical and physical processes alter the structure and chemical composition of dust grains as they enter the protoplanetary disk and move closer to the forming star. Therefore, a lot can be learned about the way stars and planets are formed by observations of dust in protoplanetary disks. Ideally, one would like to measure the dust mass, the grain size distribution, grain structure (porosity, fluffiness, the chemical composition, and all of these as a function of position in the disk. Fortunately, several observational diagnostics are available to derive constrains on these quantities. In combination with rapidly increasing quality of the data (spatial and spectral resolution, a lot of progress has been made in our understanding of dust evolution in protoplanetary disks. An excellent review of dust evolution in protoplanetary disks can be found in Testi et al. (2014.

  5. Middle turbinate angiofibroma in an elderly woman

    Directory of Open Access Journals (Sweden)

    Perić Aleksandar

    2009-01-01

    Full Text Available Background. Angiofibromas are histologically benign vascular tumors, originating from the nasopharynx, near by the area of sphenopalatine foramen. These neoplasms occur typically in male adolescents. Reports of primary extranasopharyngeal angiofibromas have appeared sporadically in the literature in English. We present the first case of an elderly woman with tumor arising from the middle turbinate, diagnosed as angiofibroma. Case report. A 63-year-old female presented with left-sided nasal obstruction and epistaxis. Endoscopic evaluation revealed a polypoid mass arising from the anteroinferior portion of the left middle turbinate. Computed tomography (CT scan showed a soft-tissue opacity that filled the anterior part of the left nasal cavity. After the endoscopic excision of the mass, postoperative pathohistological and immunohistochemical analysis confirmed the diagnosis of an angiofibroma. Two years later, the patient was free of symptoms and without endoscopic evidence of recurrence. Conclusion. Extranasopharyngeal angiofibromas arising from the nasal cavity are extremely rare tumors. Immunohistochemical analysis is very important in all doubtful cases, especially in those with atypical location.

  6. The Effectiveness of a NiCrY-Coating on a Powder Metallurgy Disk Superalloy

    Science.gov (United States)

    Gabb, Timothy P.; Miller, Robert A.; Nesbitt, James A.; Draper, Susan L.; Rogers, Richard B.; Telesman, Jack

    2018-01-01

    Protective ductile coatings could be necessary to mitigate oxidation and corrosion attack on superalloy disks in some turbine engine applications. However, the effects of coatings on fatigue life of the disk during service are an important concern. The objective of this study was to investigate how such a coating could perform after varied post-coating processing. Cylindrical gage fatigue specimens of powder metallurgy-processed disk superalloy LSHR were coated with a NiCrY coating, shot peened, preparation treated, exposed, and then subjected to fatigue at high temperature. The effects of varied shot peening, preparation treatment, and exposures on fatigue life with and without the coating were compared. Each of these variables and several of their interactions significantly influenced fatigue life.

  7. Parallel Readout of Optical Disks

    Science.gov (United States)

    1992-08-01

    r(x,y) is the apparent reflectance function of the disk surface including the phase error. The illuminat - ing optics should be chosen so that Er(x,y...of the light uniformly illuminat - ing the chip, Ap = 474\\im 2 is the area of photodiode, and rs is the time required to switch the synapses. Figure...reference beam that is incident from the right. Once the hologram is recorded the input is blocked and the disk is illuminat - ed. Lens LI takes the

  8. The Disk Mass Project: breaking the disk-halo degeneracy

    NARCIS (Netherlands)

    Verheijen, Marc A. W.; Bershady, Matthew A.; Swaters, Rob A.; Andersen, David R.; Westfall, Kyle B.; DE JONG, R. S.

    2007-01-01

    Little is known about the content and distribution of dark matter in spiral galaxies. To break the degeneracy in galaxy rotation curve decompositions, which allows a wide range of dark matter halo density profiles, an independent measure of the mass surface density of stellar disks is needed. Here,

  9. Investigation of a Cross-Correlation Based Optical Strain Measurement Technique for Detecting radial Growth on a Rotating Disk

    Science.gov (United States)

    Clem, Michelle M.; Woike, Mark R.

    2013-01-01

    The Aeronautical Sciences Project under NASA`s Fundamental Aeronautics Program is extremely interested in the development of novel measurement technologies, such as optical surface measurements in the internal parts of a flow path, for in situ health monitoring of gas turbine engines. In situ health monitoring has the potential to detect flaws, i.e. cracks in key components, such as engine turbine disks, before the flaws lead to catastrophic failure. In the present study, a cross-correlation imaging technique is investigated in a proof-of-concept study as a possible optical technique to measure the radial growth and strain field on an already cracked sub-scale turbine engine disk under loaded conditions in the NASA Glenn Research Center`s High Precision Rotordynamics Laboratory. The optical strain measurement technique under investigation offers potential fault detection using an applied high-contrast random speckle pattern and imaging the pattern under unloaded and loaded conditions with a CCD camera. Spinning the cracked disk at high speeds induces an external load, resulting in a radial growth of the disk of approximately 50.0-im in the flawed region and hence, a localized strain field. When imaging the cracked disk under static conditions, the disk will be undistorted; however, during rotation the cracked region will grow radially, thus causing the applied particle pattern to be .shifted`. The resulting particle displacements between the two images will then be measured using the two-dimensional cross-correlation algorithms implemented in standard Particle Image Velocimetry (PIV) software to track the disk growth, which facilitates calculation of the localized strain field. In order to develop and validate this optical strain measurement technique an initial proof-of-concept experiment is carried out in a controlled environment. Using PIV optimization principles and guidelines, three potential speckle patterns, for future use on the rotating disk, are developed

  10. Hollow waveguide cavity ringdown spectroscopy

    Science.gov (United States)

    Dreyer, Chris (Inventor); Mungas, Greg S. (Inventor)

    2012-01-01

    Laser light is confined in a hollow waveguide between two highly reflective mirrors. This waveguide cavity is used to conduct Cavity Ringdown Absorption Spectroscopy of loss mechanisms in the cavity including absorption or scattering by gases, liquid, solids, and/or optical elements.

  11. Optimization of photonic crystal cavities

    DEFF Research Database (Denmark)

    Wang, Fengwen; Sigmund, Ole

    2017-01-01

    We present optimization of photonic crystal cavities. The optimization problem is formulated to maximize the Purcell factor of a photonic crystal cavity. Both topology optimization and air-hole-based shape optimization are utilized for the design process. Numerical results demonstrate...... that the Purcell factor of the photonic crystal cavity can be significantly improved through optimization....

  12. Nuclear reactor cavity streaming shield

    International Nuclear Information System (INIS)

    Klotz, R.J.; Stephen, D.W.

    1978-01-01

    The upper portion of a nuclear reactor vessel supported in a concrete reactor cavity has a structure mounted below the top of the vessel between the outer vessel wall and the reactor cavity wall which contains hydrogenous material which will attenuate radiation streaming upward between vessel and the reactor cavity wall while preventing pressure buildup during a loss of coolant accident

  13. KINEMATICS OF THE CO GAS IN THE INNER REGIONS OF THE TW Hya DISK

    Energy Technology Data Exchange (ETDEWEB)

    Rosenfeld, Katherine A.; Qi Chunhua; Andrews, Sean M.; Wilner, David J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Corder, Stuartt A. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Dullemond, C. P. [Institut fuer Theoretische Astrophysik, Universitaet Heidelberg, Albert-Ueberle-Str. 2, D-69120 Heidelberg (Germany); Lin Shinyi [Department of Physics, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093 (United States); Hughes, A. M. [Department of Astronomy, University of California at Berkeley, 601 Campbell Hall, Berkeley, CA 94720 (United States); D' Alessio, Paola [Centro de Radioastronomia y Astrofisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 72-3 (Xangari), 58089 Morelia, Michoacan (Mexico); Ho, P. T. P. [Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 106, Taiwan (China)

    2012-10-01

    We present a detailed analysis of the spatially and spectrally resolved {sup 12}CO J = 2-1 and J = 3-2 emission lines from the TW Hya circumstellar disk, based on science verification data from the Atacama Large Millimeter/submillimeter Array (ALMA). These lines exhibit substantial emission in their high-velocity wings (with projected velocities out to 2.1 km s{sup -1}, corresponding to intrinsic orbital velocities >20 km s{sup -1}) that trace molecular gas as close as 2 AU from the central star. However, we are not able to reproduce the intensity of these wings and the general spatio-kinematic pattern of the lines with simple models for the disk structure and kinematics. Using three-dimensional non-local thermodynamic equilibrium molecular excitation and radiative transfer calculations, we construct some alternative models that successfully account for these features by modifying either (1) the temperature structure of the inner disk (inside the dust-depleted disk cavity; r < 4 AU), (2) the intrinsic (Keplerian) disk velocity field, or (3) the distribution of disk inclination angles (a warp). The latter approach is particularly compelling because a representative warped disk model qualitatively reproduces the observed azimuthal modulation of optical light scattered off the disk surface. In any model scenario, the ALMA data clearly require a substantial molecular gas reservoir located inside the region where dust optical depths are known to be substantially diminished in the TW Hya disk, in agreement with previous studies based on infrared spectroscopy. The results from these updated model prescriptions are discussed in terms of their potential physical origins, which might include dynamical perturbations from a low-mass companion with an orbital separation of a few AU.

  14. Transient stress control of aeroengine disks based on active thermal management

    International Nuclear Information System (INIS)

    Ding, Shuiting; Wang, Ziyao; Li, Guo; Liu, Chuankai; Yang, Liu

    2016-01-01

    Highlights: • The essence of cooling in turbine system is a process of thermal management. • Active thermal management is proposed to control transient stress of disks. • The correlation between thermal load and transient stress of disks is built. • Stress level can be declined by actively adjusting the thermal load distribution. • Artificial temperature gradient can be used to counteract stress from rotating. - Abstract: The physical essence of cooling in the turbine system is a process of thermal management. In order to overcome the limits of passive thermal management based on thermal protection, the concept of active thermal management based on thermal load redistribution has been proposed. On this basis, this paper focuses on a near real aeroengine disk during a transient process and studies the stress control mechanism of active thermal management in transient conditions by a semi-analytical method. Active thermal management is conducted by imposing extra heating energy on the disk hub, which is represented by the coefficient of extra heat flow η. The results show that the transient stress level can be effectively controlled by actively adjusting the thermal load distribution. The decline ratio of the peak equivalent stress of the disk hub can be 9.0% for active thermal management load condition (η = 0.2) compared with passive condition (η = 0), even at a rotation speed of 10,000 r/min. The reason may be that the temperature distribution of the disk turns into an artificial V-shape because of the extra heating energy on the hub, and the resulting thermal stresses induced by the negative temperature gradients counteract parts of the stress from rotating.

  15. Progress of a Cross-Correlation Based Optical Strain Measurement Technique for Detecting Radial Growth on a Rotating Disk

    Science.gov (United States)

    Clem, Michelle M.; Woike, Mark R.; Abdul-Aziz, Ali

    2014-01-01

    The Aeronautical Sciences Project under NASA's Fundamental Aeronautics Program is interested in the development of novel measurement technologies, such as optical surface measurements for the in situ health monitoring of critical constituents of the internal flow path. In situ health monitoring has the potential to detect flaws, i.e. cracks in key components, such as engine turbine disks, before the flaws lead to catastrophic failure. The present study, aims to further validate and develop an optical strain measurement technique to measure the radial growth and strain field of an already cracked disk, mimicking the geometry of a sub-scale turbine engine disk, under loaded conditions in the NASA Glenn Research Center's High Precision Rotordynamics Laboratory. The technique offers potential fault detection by imaging an applied high-contrast random speckle pattern under unloaded and loaded conditions with a CCD camera. Spinning the cracked disk at high speeds (loaded conditions) induces an external load, resulting in a radial growth of the disk of approximately 50.0-µm in the flawed region and hence, a localized strain field. When imaging the cracked disk under static conditions, the disk will be undistorted; however, during rotation the cracked region will grow radially, thus causing the applied particle pattern to be 'shifted'. The resulting particle displacements between the two images is measured using the two-dimensional cross-correlation algorithms implemented in standard Particle Image Velocimetry (PIV) software to track the disk growth, which facilitates calculation of the localized strain field. A random particle distribution is adhered onto the surface of the cracked disk and two bench top experiments are carried out to evaluate the technique's ability to measure the induced particle displacements. The disk is shifted manually using a translation stage equipped with a fine micrometer and a hotplate is used to induce thermal growth of the disk, causing the

  16. Inverse Design of Single- and Multi-Rotor Horizontal Axis Wind Turbine Blades using Computational Fluid Dynamics

    OpenAIRE

    Moghadassian, Behnam; Sharma, Anupam

    2017-01-01

    A method for inverse design of horizontal axis wind turbines (HAWTs) is presented in this paper. The direct solver for aerodynamic analysis solves the Reynolds Averaged Navier Stokes (RANS) equations, where the effect of the turbine rotor is modeled as momentum sources using the actuator disk model (ADM); this approach is referred to as RANS/ADM. The inverse problem is posed as follows: for a given selection of airfoils, the objective is to find the blade geometry (described as blade twist an...

  17. Turbine blade vibration dampening

    Science.gov (United States)

    Cornelius, C.C.; Pytanowski, G.P.; Vendituoli, J.S.

    1997-07-08

    The present turbine wheel assembly increases component life and turbine engine longevity. The combination of the strap and the opening combined with the preestablished area of the outer surface of the opening and the preestablished area of the outer circumferential surface of the strap and the friction between the strap and the opening increases the life and longevity of the turbine wheel assembly. Furthermore, the mass ``M`` or combined mass ``CM`` of the strap or straps and the centrifugal force assist in controlling vibrations and damping characteristics. 5 figs.

  18. Coevolution of Binaries and Circumbinary Gaseous Disks

    Science.gov (United States)

    Fleming, David; Quinn, Thomas R.

    2018-04-01

    The recent discoveries of circumbinary planets by Kepler raise questions for contemporary planet formation models. Understanding how these planets form requires characterizing their formation environment, the circumbinary protoplanetary disk, and how the disk and binary interact. The central binary excites resonances in the surrounding protoplanetary disk that drive evolution in both the binary orbital elements and in the disk. To probe how these interactions impact both binary eccentricity and disk structure evolution, we ran N-body smooth particle hydrodynamics (SPH) simulations of gaseous protoplanetary disks surrounding binaries based on Kepler 38 for 10^4 binary orbital periods for several initial binary eccentricities. We find that nearly circular binaries weakly couple to the disk via a parametric instability and excite disk eccentricity growth. Eccentric binaries strongly couple to the disk causing eccentricity growth for both the disk and binary. Disks around sufficiently eccentric binaries strongly couple to the disk and develop an m = 1 spiral wave launched from the 1:3 eccentric outer Lindblad resonance (EOLR). This wave corresponds to an alignment of gas particle longitude of periastrons. We find that in all simulations, the binary semi-major axis decays due to dissipation from the viscous disk.

  19. Colloquium: cavity optomechanics

    CERN Multimedia

    2011-01-01

    Monday 14 November 2011, 17:00 Ecole de Physique, Auditoire Stueckelberg Université de Genève Cavity optomechanics: controlling micro mechanical oscillators with laser light Prof. Tobias Kippenberg EPFL, Lausanne Laser light can be used to cool and to control trapped ions, atoms and molecules at the quantum level. This has lead to spectacular advances such as the most precise atomic clocks. An outstanding frontier is the control with lasers of nano- and micro-mechancial systems. Recent advances in cavity optomechanics have allowed such elementary control for the first time, enabling mechanical systems to be ground state cooled leading to readout with quantum limited sensitivity and permitting to explore new device concepts resulting from radiation pressure.  

  20. THICK-DISK EVOLUTION INDUCED BY THE GROWTH OF AN EMBEDDED THIN DISK

    International Nuclear Information System (INIS)

    Villalobos, Alvaro; Helmi, Amina; Kazantzidis, Stelios

    2010-01-01

    We perform collisionless N-body simulations to investigate the evolution of the structural and kinematical properties of simulated thick disks induced by the growth of an embedded thin disk. The thick disks used in the present study originate from cosmologically common 5:1 encounters between initially thin primary disk galaxies and infalling satellites. The growing thin disks are modeled as static gravitational potentials and we explore a variety of growing-disk parameters that are likely to influence the response of thick disks. We find that the final thick-disk properties depend strongly on the total mass and radial scale length of the growing thin disk, and much less sensitively on its growth timescale and vertical scale height as well as the initial sense of thick-disk rotation. Overall, the growth of an embedded thin disk can cause a substantial contraction in both the radial and vertical direction, resulting in a significant decrease in the scale lengths and scale heights of thick disks. Kinematically, a growing thin disk can induce a notable increase in the mean rotation and velocity dispersions of thick-disk stars. We conclude that the reformation of a thin disk via gas accretion may play a significant role in setting the structure and kinematics of thick disks, and thus it is an important ingredient in models of thick-disk formation.

  1. Leaching materials from cavities

    International Nuclear Information System (INIS)

    Hodgson, T.D.; Jordan, T.W.J.

    1980-01-01

    A material is leached from a cavity by contacting the material with a liquid and subjecting the liquid to a number of pressure cycles, each pressure cycle involving a decrease in pressure to cause boiling of the liquid, followed by a rise in pressure to inhibit the boiling. The method may include the step of heating the liquid to a temperature near to its boiling point. The material may be nuclear fuel pellets or calcium carbonate pellets. (author)

  2. Superconducting cavities for HERA

    International Nuclear Information System (INIS)

    Dwersteg, B.; Ebeling, W.; Moeller, W.D.; Renken, D.; Proch, D.; Sekutowicz, J.; Susta, J.; Tong, D.

    1988-01-01

    Superconducting 500 MHz cavities are developed to demonstrate the feasibility of upgrading the e-beam energy of the HERA storage ring. A prototype module with 2 x 4 cell resonators and appropriate fundamental and higher mode couplers has been designed at DESY and is being built by industrial firms. The design and results of RF and cryogenic measurements are reported in detail. 17 references, 10 figures, 2 tables

  3. Compact objects and accretion disks

    NARCIS (Netherlands)

    Blandford, Roger; Agol, Eric; Broderick, Avery; Heyl, Jeremy; Koopmans, Leon; Lee, Hee-Won

    2002-01-01

    Recent developments in the spectropolarimetric study of compact objects, specifically black holes (stellar and massive) and neutron stars are reviewed. The lectures are organized around five topics: disks, jets, outflows, neutron stars and black holes. They emphasize physical mechanisms and are

  4. Disk Operating System User's Guide

    Science.gov (United States)

    1972-05-01

    This document serves the purpose of bringing together in one place most of the information a user needs to use the DDP-516 Disk Operating System, (DOS). DOS is a core resident, one user, console-oriented operating system which allows the user to cont...

  5. Gas Evolution in Protoplanetary Disks

    NARCIS (Netherlands)

    Woitke, Peter; Dent, Bill; Thi, Wing-Fai; Sibthorpe, Bruce; Rice, Ken; Williams, Jonathan; Sicilia-Aguilar, Aurora; Brown, Joanna; Kamp, Inga; Pascucci, Ilaria; Alexander, Richard; Roberge, Aki

    2009-01-01

    This article summarizes a Splinter Session at the Cool Stars XV conference in St. Andrews with 3 review and 4 contributed talks. The speakers have discussed various approaches to understand the structure and evolution of the gas component in protoplanetary disks. These ranged from observational

  6. Materials and structural aspects of advanced gas-turbine helicopter engines

    Science.gov (United States)

    Freche, J. C.; Acurio, J.

    1979-01-01

    Advances in materials, coatings, turbine cooling technology, structural and design concepts, and component-life prediction of helicopter gas-turbine-engine components are presented. Stationary parts including the inlet particle separator, the front frame, rotor tip seals, vanes and combustors and rotating components - compressor blades, disks, and turbine blades - are discussed. Advanced composite materials are considered for the front frame and compressor blades, prealloyed powder superalloys will increase strength and reduce costs of disks, the oxide dispersion strengthened alloys will have 100C higher use temperature in combustors and vanes than conventional superalloys, ceramics will provide the highest use temperature of 1400C for stator vanes and 1370C for turbine blades, and directionally solidified eutectics will afford up to 50C temperature advantage at turbine blade operating conditions. Coatings for surface protection at higher surface temperatures and design trends in turbine cooling technology are discussed. New analytical methods of life prediction such as strain gage partitioning for high temperature prediction, fatigue life, computerized prediction of oxidation resistance, and advanced techniques for estimating coating life are described.

  7. Numerical Investigation of the Interaction between Mainstream and Tip Shroud Leakage Flow in a 2-Stage Low Pressure Turbine

    Science.gov (United States)

    Jia, Wei; Liu, Huoxing

    2014-06-01

    The pressing demand for future advanced gas turbine requires to identify the losses in a turbine and to understand the physical mechanisms producing them. In low pressure turbines with shrouded blades, a large portion of these losses is generated by tip shroud leakage flow and associated interaction. For this reason, shroud leakage losses are generally grouped into the losses of leakage flow itself and the losses caused by the interaction between leakage flow and mainstream. In order to evaluate the influence of shroud leakage flow and related losses on turbine performance, computational investigations for a 2-stage low pressure turbine is presented and discussed in this paper. Three dimensional steady multistage calculations using mixing plane approach were performed including detailed tip shroud geometry. Results showed that turbines with shrouded blades have an obvious advantage over unshrouded ones in terms of aerodynamic performance. A loss mechanism breakdown analysis demonstrated that the leakage loss is the main contributor in the first stage while mixing loss dominates in the second stage. Due to the blade-to-blade pressure gradient, both inlet and exit cavity present non-uniform leakage injection and extraction. The flow in the exit cavity is filled with cavity vortex, leakage jet attached to the cavity wall and recirculation zone induced by main flow ingestion. Furthermore, radial gap and exit cavity size of tip shroud have a major effect on the yaw angle near the tip region in the main flow. Therefore, a full calculation of shroud leakage flow is necessary in turbine performance analysis and the shroud geometric features need to be considered during turbine design process.

  8. MAPPING H-BAND SCATTERED LIGHT EMISSION IN THE MYSTERIOUS SR21 TRANSITIONAL DISK

    International Nuclear Information System (INIS)

    Follette, Katherine B.; Close, Laird; Tamura, Motohide; Hashimoto, Jun; Kwon, Jungmi; Kandori, Ryo; Whitney, Barbara; Grady, Carol; Andrews, Sean M.; Wisniewski, John; Brandt, Timothy D.; Dong, Ruobing; Mayama, Satoshi; Abe, Lyu; Brandner, Wolfgang; Feldt, Markus; Carson, Joseph; Currie, Thayne; Egner, Sebastian E.; Goto, Miwa

    2013-01-01

    We present the first near infrared (NIR) spatially resolved images of the circumstellar transitional disk around SR21. These images were obtained with the Subaru HiCIAO camera, adaptive optics, and the polarized differential imaging technique. We resolve the disk in scattered light at H-band for stellocentric 0.''1 ≤ r ≤ 0.''6 (12 ∼ –6 ) are inconsistent with our H-band images when they are assumed to carry over to small grains, suggesting that surface grains scattering in the NIR either survive or are generated by whatever mechanism is clearing the disk midplane. In fact, the radial polarized intensity profile of our H-band observations is smooth and steeply inwardly-increasing (r –3 ), with no evidence of a break at the 36 AU sub-mm cavity wall. We hypothesize that this profile is dominated by an optically thin disk envelope or atmosphere component. We also discuss the compatibility of our data with the previously postulated existence of a sub-stellar companion to SR21 at r ∼ 10-20 AU, and find that we can neither exclude nor verify this scenario. This study demonstrates the power of multiwavelength imaging of transitional disks to inform modeling efforts, including the debate over precisely what physical mechanism is responsible for clearing these disks of their large midplane grains.

  9. Superconducting wind turbine generators

    DEFF Research Database (Denmark)

    Abrahamsen, Asger Bech; Mijatovic, Nenad; Seiler, Eugen

    2010-01-01

    , the main challenge of the superconducting direct drive technology is to prove that the reliability is superior to the alternative drive trains based on gearboxes or permanent magnets. A strategy of successive testing of superconducting direct drive trains in real wind turbines of 10 kW, 100 kW, 1 MW and 10......We have examined the potential of 10 MW superconducting direct drive generators to enter the European offshore wind power market and estimated that the production of about 1200 superconducting turbines until 2030 would correspond to 10% of the EU offshore market. The expected properties of future...... offshore turbines of 8 and 10 MW have been determined from an up-scaling of an existing 5 MW turbine and the necessary properties of the superconducting drive train are discussed. We have found that the absence of the gear box is the main benefit and the reduced weight and size is secondary. However...

  10. Turbine disintegration debris

    International Nuclear Information System (INIS)

    Holecek, M.; Martinec, P.; Malotin, V.; Peleska, P.; Voldrich, J.

    1997-01-01

    The determination, evaluation and analysis of possible unacceptable consequences of the disintegration turbine (turbo-set) missiles is a part of the wide conceived project put by the company Nuclear Power Plant Mochovce (NPPM), the Slovak Republic. The aim of the project is to take measures reducing the probability of striking a target of safety importance in NPPM by a turbine (turbo-set) missile below the prescribed limit of 10 -6 per turbine year. Following the IAEA Safety Guides, all potential events leading to the generation of a missile are to be analysed. It is necessary to evaluate the probability of unacceptable consequences of such missiles and analyse each event whose probability is not acceptable low. This complex problem thus carries especially: complex analysis of fragment generation; evaluation of the probability of unacceptable events; location of strike zones of possible turbine missiles; assessment the possibility of the turbo-set casing penetration; and projection of additional design requirements if necessary

  11. Monitoring of wind turbines

    Science.gov (United States)

    White, Jonathan R.; Adams, Douglas E.; Paquette, Josh

    2017-07-25

    Method and apparatus for determining the deflection or curvature of a rotating blade, such as a wind turbine blade or a helicopter blade. Also, methods and apparatus for establishing an inertial reference system on a rotating blade.

  12. Crab cavities for linear colliders

    CERN Document Server

    Burt, G; Carter, R; Dexter, A; Tahir, I; Beard, C; Dykes, M; Goudket, P; Kalinin, A; Ma, L; McIntosh, P; Shulte, D; Jones, Roger M; Bellantoni, L; Chase, B; Church, M; Khabouline, T; Latina, A; Adolphsen, C; Li, Z; Seryi, Andrei; Xiao, L

    2008-01-01

    Crab cavities have been proposed for a wide number of accelerators and interest in crab cavities has recently increased after the successful operation of a pair of crab cavities in KEK-B. In particular crab cavities are required for both the ILC and CLIC linear colliders for bunch alignment. Consideration of bunch structure and size constraints favour a 3.9 GHz superconducting, multi-cell cavity as the solution for ILC, whilst bunch structure and beam-loading considerations suggest an X-band copper travelling wave structure for CLIC. These two cavity solutions are very different in design but share complex design issues. Phase stabilisation, beam loading, wakefields and mode damping are fundamental issues for these crab cavities. Requirements and potential design solutions will be discussed for both colliders.

  13. On Fallback Disks around Young Neutron Stars

    Science.gov (United States)

    Alpar, M. Ali; Ertan, Ü.; Erkut, M. H.

    2006-08-01

    Some bound matter in the form of a fallback disk may be an initial parameter of isolated neutron stars at birth, which, along with the initial rotation rate and dipole (and higher multipole) magnetic moments, determines the evolution of neutron stars and the categories into which they fall. This talk reviews the possibilities of fallback disk models in explaining properties of isolated neutron stars of different categories. Recent observations of a fallback disk and observational limits on fallback disks will also be discussed.

  14. RTOD- RADIAL TURBINE OFF-DESIGN PERFORMANCE ANALYSIS

    Science.gov (United States)

    Glassman, A. J.

    1994-01-01

    The RTOD program was developed to accurately predict radial turbine off-design performance. The radial turbine has been used extensively in automotive turbochargers and aircraft auxiliary power units. It is now being given serious consideration for primary powerplant applications. In applications where the turbine will operate over a wide range of power settings, accurate off-design performance prediction is essential for a successful design. RTOD predictions have already illustrated a potential improvement in off-design performance offered by rotor back-sweep for high-work-factor radial turbines. RTOD can be used to analyze other potential performance enhancing design features. RTOD predicts the performance of a radial turbine (with or without rotor blade sweep) as a function of pressure ratio, speed, and stator setting. The program models the flow with the following: 1) stator viscous and trailing edge losses; 2) a vaneless space loss between the stator and the rotor; and 3) rotor incidence, viscous, trailing-edge, clearance, and disk friction losses. The stator and rotor viscous losses each represent the combined effects of profile, endwall, and secondary flow losses. The stator inlet and exit and the rotor inlet flows are modeled by a mean-line analysis, but a sector analysis is used at the rotor exit. The leakage flow through the clearance gap in a pivoting stator is also considered. User input includes gas properties, turbine geometry, and the stator and rotor viscous losses at a reference performance point. RTOD output includes predicted turbine performance over a specified operating range and any user selected flow parameters. The RTOD program is written in FORTRAN IV for batch execution and has been implemented on an IBM 370 series computer with a central memory requirement of approximately 100K of 8 bit bytes. The RTOD program was developed in 1983.

  15. Noise from wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Fegeant, Olivier [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Building Sciences

    2002-02-01

    A rapid growth of installed wind power capacity is expected in the next few years. However, the siting of wind turbines on a large scale raises concerns about their environmental impact, notably with respect to noise. To this end, variable speed wind turbines offer a promising solution for applications in densely populated areas like the European countries, as this design would enable an efficient utilisation of the masking effect due to ambient noise. In rural and recreational areas where wind turbines are sited, the ambient noise originates from the action of wind on the vegetation and about the listener's ear (pseudo-noise). It shows a wind speed dependence similar to that of the noise from a variable speed wind turbine and can therefore mask the latter for a wide range of conditions. However, a problem inherent to the design of these machines is their proclivity to pure tone generation, because of the enhanced difficulty of avoiding structural resonances in the mechanical parts. Pure tones are deemed highly annoying and are severely regulated by most noise policies. In relation to this problem, the vibration transmission of structure-borne sound to the tower of the turbine is investigated, in particular when the tower is stiffened at its upper end. Furthermore, since noise annoyance due to wind turbine is mostly a masking issue, the wind-related sources of ambient noise are studied and their masking potentials assessed. With this aim, prediction models for wind-induced vegetation noise and pseudo-noise have been developed. Finally, closely related to the effect of masking, is the difficulty, regularly encountered by local authorities and wind farm developers, to measure noise immission from wind turbines. A new measurement technique has thus been developed in the course of this work. Through improving the signal-to-noise ratio between wind turbine noise and ambient noise, the new technique yields more accurate measurement results.

  16. Numerical simulations of flow fields through conventionally controlled wind turbines and wind farms

    International Nuclear Information System (INIS)

    Yilmaz, Ali Emre; Meyers, Johan

    2014-01-01

    In the current study, an Actuator-Line Model (ALM) is implemented in our in-house pseudo-spectral LES solver SP-WIND, including a turbine controller. Below rated wind speed, turbines are controlled by a standard-torque-controller aiming at maximum power extraction from the wind. Above rated wind speed, the extracted power is limited by a blade pitch controller which is based on a proportional-integral type control algorithm. This model is used to perform a series of single turbine and wind farm simulations using the NREL 5MW turbine. First of all, we focus on below-rated wind speed, and investigate the effect of the farm layout on the controller calibration curves. These calibration curves are expressed in terms of nondimensional torque and rotational speed, using the mean turbine-disk velocity as reference. We show that this normalization leads to calibration curves that are independent of wind speed, but the calibration curves do depend on the farm layout, in particular for tightly spaced farms. Compared to turbines in a lone-standing set-up, turbines in a farm experience a different wind distribution over the rotor due to the farm boundary-layer interaction. We demonstrate this for fully developed wind-farm boundary layers with aligned turbine arrangements at different spacings (5D, 7D, 9D). Further we also compare calibration curves obtained from full farm simulations with calibration curves that can be obtained at a much lower cost using a minimal flow unit

  17. CIRCUMSTELLAR DEBRIS DISKS: DIAGNOSING THE UNSEEN PERTURBER

    Energy Technology Data Exchange (ETDEWEB)

    Nesvold, Erika R. [Department of Terrestrial Magnetism, Carnegie Institution for Science, 5241 Broad Branch Rd., Washington, DC 20015 (United States); Naoz, Smadar; Vican, Laura [Department of Physics and Astronomy, UCLA, 475 Portola Plaza, Los Angeles, CA 90095 (United States); Farr, Will M. [School of Physics and Astronomy, University of Birmingham, Birmingham, B15 2TT (United Kingdom)

    2016-07-20

    The first indication of the presence of a circumstellar debris disk is usually the detection of excess infrared emission from the population of small dust grains orbiting the star. This dust is short-lived, requiring continual replenishment, and indicating that the disk must be excited by an unseen perturber. Previous theoretical studies have demonstrated that an eccentric planet orbiting interior to the disk will stir the larger bodies in the belt and produce dust via interparticle collisions. However, motivated by recent observations, we explore another possible mechanism for heating a debris disk: a stellar-mass perturber orbiting exterior to and inclined to the disk and exciting the disk particles’ eccentricities and inclinations via the Kozai–Lidov mechanism. We explore the consequences of an exterior perturber on the evolution of a debris disk using secular analysis and collisional N -body simulations. We demonstrate that a Kozai–Lidov excited disk can generate a dust disk via collisions and we compare the results of the Kozai–Lidov excited disk with a simulated disk perturbed by an interior eccentric planet. Finally, we propose two observational tests of a dust disk that can distinguish whether the dust was produced by an exterior brown dwarf or stellar companion or an interior eccentric planet.

  18. NASA Lunar and Meteorite Sample Disk Program

    Science.gov (United States)

    Foxworth, Suzanne

    2017-01-01

    The Lunar and Meteorite Sample Disk Program is designed for K-12 classroom educators who work in K-12 schools, museums, libraries, or planetariums. Educators have to be certified to borrow the Lunar and Meteorite Sample Disks by attending a NASA Certification Workshop provided by a NASA Authorized Sample Disk Certifier.

  19. PROTOPLANETARY DISK RESONANCES AND TYPE I MIGRATION

    International Nuclear Information System (INIS)

    Tsang, David

    2011-01-01

    Waves reflected by the inner edge of a protoplanetary disk are shown to significantly modify Type I migration, even allowing the trapping of planets near the inner disk edge for small planets in a range of disk parameters. This may inform the distribution of planets close to their central stars, as observed recently by the Kepler mission.

  20. A COMMON SOURCE OF ACCRETION DISK TILT

    International Nuclear Information System (INIS)

    Montgomery, M. M.; Martin, E. L.

    2010-01-01

    Many different system types retrogradely precess, and retrograde precession could be from a tidal torque by the secondary on a misaligned accretion disk. However, a source that causes and maintains disk tilt is unknown. In this work, we show that accretion disks can tilt due to a force called lift. Lift results from differing gas stream supersonic speeds over and under an accretion disk. Because lift acts at the disk's center of pressure, a torque is applied around a rotation axis passing through the disk's center of mass. The disk responds to lift by pitching around the disk's line of nodes. If the gas stream flow ebbs, then lift also ebbs and the disk attempts to return to its original orientation. To first approximation, lift does not depend on magnetic fields or radiation sources but does depend on the mass and the surface area of the disk. Also, for disk tilt to be initiated, a minimum mass transfer rate must be exceeded. For example, a 10 -11 M sun disk around a 0.8 M sun compact central object requires a mass transfer rate greater than ∼ 8 x 10 -11 M sun yr -1 , a value well below the known mass transfer rates in cataclysmic variable dwarf novae systems that retrogradely precess and exhibit negative superhumps in their light curves and a value well below mass transfer rates in protostellar-forming systems.

  1. Numerical Investigation of Merged and Non-merged Flame of a Twin Cavity Annular Trapped Vortex Combustor

    Directory of Open Access Journals (Sweden)

    Pravendra Kumar

    2016-09-01

    Full Text Available : The present work is focused to characterize numerically the merged and non-merged flame emanating from the cavities in downstream of twin cavity Annular Trapped Vortex Combustor (ATVC.The isotherm corresponding to the auto-ignition temperature is used to locate the merging point of the flame in the mainstream region along the combustor length. In present study, the cavity flame is said to be merged only if this isotherm corresponding to self-ignition temperature of methane is located within 20 percentage of the combustor length from aft wall of cavities. It is interesting to note that on increasing the power loading parameter (PLP in mainstream for a constant power loading parameter ratio (outer to inner cavity, the merging point gets shifted towards the cavity aft-wall. This leads to the reduction of combustor length and subsequent reduction in overall weight of the gas turbine engine.

  2. European wind turbine catalogue

    International Nuclear Information System (INIS)

    1994-01-01

    The THERMIE European Community programme is designed to promote the greater use of European technology and this catalogue contributes to the fulfillment of this aim by dissemination of information on 50 wind turbines from 30 manufacturers. These turbines are produced in Europe and are commercially available. The manufacturers presented produce and sell grid-connected turbines which have been officially approved in countries where this approval is acquired, however some of the wind turbines included in the catalogue have not been regarded as fully commercially available at the time of going to print. The entries, which are illustrated by colour photographs, give company profiles, concept descriptions, measured power curves, prices, and information on design and dimension, safety systems, stage of development, special characteristics, annual energy production, and noise pollution. Lists are given of wind turbine manufacturers and agents and of consultants and developers in the wind energy sector. Exchange rates used in the conversion of the prices of wind turbines are also given. Information can be found on the OPET network (organizations recognised by the European Commission as an Organization for the Promotion of Energy Technologies (OPET)). An article describes the development of the wind power industry during the last 10-15 years and another article on certification aims to give an overview of the most well-known and acknowledged type approvals currently issued in Europe. (AB)

  3. Wind turbines and health

    International Nuclear Information System (INIS)

    Rideout, K.; Copes, R.; Bos, C.

    2010-01-01

    This document summarized the potential health hazards associated with wind turbines, such as noise and low frequency sound, vibration and infrasound; electromagnetic fields (EMF); shadow flicker; and ice throw and structural failure. Various symptoms can be attributed to wind turbines, including dizziness, sleep disruption, and headaches. A review of available research regarding potential health affects to residents living in close proximity to wind turbines showed that the sound level associated with wind turbines at common residential setbacks is not sufficient to damage hearing, but may lead to annoyance and sleep disturbance. Research has shown that wind turbines are not a significant source of EMF exposure, and although shadows caused by the blades may be annoying, they are not likely to cause epileptic seizures at normal operational speeds. The risk of injury from ice throw can be minimized with setbacks of 200 to 400 m. Examples of Canadian wind turbine setback guidelines and regulations were also offered. It was concluded that setbacks and operational guidelines can be utilized in combination to address safety hazards, sound levels, land use issues, and impacts on people. 46 refs., 2 tabs., 2 figs.

  4. Wind turbines and infrasound

    International Nuclear Information System (INIS)

    Howe, B.

    2006-01-01

    This paper provided the results of a study conducted to assess the impacts of wind farm-induced infrasound on nearby residences and human populations. Infrasound occurs at frequencies below those considered as detectable by human hearing. Infrasonic levels caused by wind turbines are often similar to ambient levels of 85 dBG or lower that are caused by wind in the natural environment. This study examined the levels at which infrasound poses a threat to human health or can be considered as an annoyance. The study examined levels of infrasound caused by various types of wind turbines, and evaluated acoustic phenomena and characteristics associated with wind turbines. Results of the study suggested that infrasound near modern wind turbines is typically not perceptible to humans through either auditory or non-auditory mechanisms. However, wind turbines often create an audible broadband noise whose amplitude can be modulated at low frequencies. A review of both Canadian and international studies concluded that infrasound generated by wind turbines should not significantly impact nearby residences or human populations. 17 refs., 2 tabs., 4 figs

  5. Detection of cavitation in hydraulic turbines

    Science.gov (United States)

    Escaler, Xavier; Egusquiza, Eduard; Farhat, Mohamed; Avellan, François; Coussirat, Miguel

    2006-05-01

    An experimental investigation has been carried out in order to evaluate the detection of cavitation in actual hydraulic turbines. The methodology is based on the analysis of structural vibrations, acoustic emissions and hydrodynamic pressures measured in the machine. The proposed techniques have been checked in real prototypes suffering from different types of cavitation. In particular, one Kaplan, two Francis and one Pump-Turbine have been investigated in the field. Additionally, one Francis located in a laboratory has also been tested. First, a brief description of the general features of cavitation phenomenon is given as well as of the main types of cavitation occurring in hydraulic turbines. The work presented here is focused on the most important ones which are the leading edge cavitation due to its erosive power, the bubble cavitation because it affects the machine performance and the draft tube swirl that limits the operation stability. Cavitation detection is based on the previous understanding of the cavity dynamics and its location inside the machine. This knowledge has been gained from flow visualisations and measurements in laboratory devices such as a high-speed cavitation tunnel and a reduced scale turbine test rig. The main techniques are the study of the high frequency spectral content of the signals and of their amplitude demodulation for a given frequency band. Moreover, low frequency spectral content can also be used in certain cases. The results obtained for the various types of cavitation found in the selected machines are presented and discussed in detail in the paper. Conclusions are drawn about the best sensor, measuring location, signal processing and analysis for each type of cavitation, which serve to validate and to improve the detection techniques.

  6. Wind turbines and idiopathic symptoms

    DEFF Research Database (Denmark)

    Blanes-Vidal, Victoria; Schwartz, Joel

    2016-01-01

    Whether or not wind turbines pose a risk to human health is a matter of heated debate. Personal reactions to other environmental exposures occurring in the same settings as wind turbines may be responsible of the reported symptoms. However, these have not been accounted for in previous studies. We...... investigated whether there is an association between residential proximity to wind turbines and idiopathic symptoms, after controlling for personal reactions to other environmental co-exposures. We assessed wind turbine exposures in 454 residences as the distance to the closest wind turbine (Dw) and number...... of wind turbines

  7. ISR RF cavities

    CERN Multimedia

    1983-01-01

    In each ISR ring the radiofrequency cavities were installed in one 9 m long straight section. The RF system of the ISR had the main purpose to stack buckets of particles (most of the time protons)coming from the CPS and also to accelerate the stacked beam. The installed RF power per ring was 18 kW giving a peak accelerating voltage of 20 kV. The system had a very fine regulation feature allowing to lower the voltage down to 75 V in a smooth and well controlled fashion.

  8. Numerical Modeling of Hydrokinetic Turbines and their Environmental Effects

    Science.gov (United States)

    Javaherchi, T.; Seydel, J.; Aliseda, A.

    2010-12-01

    The search for predictable renewable energy has led research into marine hydrokinetic energy. Electricity can be generated from tidally-induced currents through turbines located in regions of high current speed and relatively low secondary flow intensity. Although significant technological challenges exist, the main obstacle in the development and commercial deployment of marine hydrokinetic (MHK) turbines is the uncertainty in the environmental effect of devices. The velocity deficit in the turbulent wake of the turbine might enhance the sedimentation process of suspended particles in the water column and lead to deposition into artificial patterns that alter the benthic ecosystem. Pressure fluctuations across turbine blades and in blade tip vortices can damage internal organs of marine species as they swim through the device. These are just a few examples of the important potential environmental effects of MHK turbines that need to be addressed and investigated a priori before pilot and large scale deployment. We have developed a hierarchy of numerical models to simulate the turbulent wake behind a well characterized two bladed turbine. The results from these models (Sliding Mesh, Rotating Reference Frame, Virtual Blade Model and Actuator Disk Model) have been validated and are been used to investigate the efficiency and physical changes introduced in the environment by single or multiple MHK turbines. We will present results from sedimenting particles and model juvenile fish, with relative densities of 1.2 and 0.95, respectively. The settling velocity and terminal location on the bottom of the tidal channel is computed and compared to the simulated flow in a channel without turbines. We have observed an enhanced sedimentation, and we will quantify the degree of enhancement and the parameter range within which it is significant. For the slightly buoyant particles representing fish, the pressure history is studied statistically with particular attention to the

  9. Angular momentum transfer in steady disk accretion

    International Nuclear Information System (INIS)

    Gorbatskij, V.G.

    1977-01-01

    The conditions of steady disk accretion have been investigated. The disk axisymmetric model is considered. It is shown that the gas is let at the outer boundary of the disk with the azimuthal velocity which is slightly less than the Kepler circular one. Gas possesses the motion quality moment which is transferred from the outer layers of the disk to the surface of the star. The steady state of the disk preserved until the inflow of the moment to the star increases its rotation velocity up to magnitudes close to the critical one

  10. Signatures of Young Planets in the Continuum Emission from Protostellar Disks

    Science.gov (United States)

    Isella, Andrea; Turner, Neal J.

    2018-06-01

    Many protostellar disks show central cavities, rings, or spiral arms likely caused by low-mass stellar or planetary companions, yet few such features are conclusively tied to bodies embedded in the disks. We note that even small features on the disk surface cast shadows, because the starlight grazes the surface. We therefore focus on accurately computing the disk thickness, which depends on its temperature. We present models with temperatures set by the balance between starlight heating and radiative cooling, which are also in vertical hydrostatic equilibrium. The planet has 20, 100, or 1000 M ⊕, ranging from barely enough to perturb the disk significantly, to clearing a deep tidal gap. The hydrostatic balance strikingly alters the appearance of the model disk. The outer walls of the planet-carved gap puff up under starlight heating, throwing a shadow across the disk beyond. The shadow appears in scattered light as a dark ring that could be mistaken for a gap opened by another more distant planet. The surface brightness contrast between outer wall and shadow for the 1000 M ⊕ planet is an order of magnitude greater than a model neglecting the temperature disturbances. The shadow is so deep that it largely hides the planet-launched outer arm of the spiral wave. Temperature gradients are such that outer low-mass planets undergoing orbital migration will converge within the shadow. Furthermore, the temperature perturbations affect the shape, size, and contrast of features at millimeter and centimeter wavelengths. Thus radiative heating and cooling are key to the appearance of protostellar disks with embedded planets.

  11. SIMULATING THE FORMATION OF MASSIVE PROTOSTARS. I. RADIATIVE FEEDBACK AND ACCRETION DISKS

    Energy Technology Data Exchange (ETDEWEB)

    Klassen, Mikhail; Pudritz, Ralph E. [Department of Physics and Astronomy, McMaster University, 1280 Main Street W, Hamilton, ON L8S 4M1 (Canada); Kuiper, Rolf [Institute of Astronomy and Astrophysics, University of Tübingen, Auf der Morgenstelle 10, D-72076 Tübingen (Germany); Peters, Thomas [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Strasse 1, D-85748 Garching (Germany); Banerjee, Robi, E-mail: klassm@mcmaster.ca [Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, D-21029 Hamburg (Germany)

    2016-05-20

    We present radiation hydrodynamic simulations of collapsing protostellar cores with initial masses of 30, 100, and 200 M {sub ⊙}. We follow their gravitational collapse and the formation of a massive protostar and protostellar accretion disk. We employ a new hybrid radiative feedback method blending raytracing techniques with flux-limited diffusion for a more accurate treatment of the temperature and radiative force. In each case, the disk that forms becomes Toomre-unstable and develops spiral arms. This occurs between 0.35 and 0.55 freefall times and is accompanied by an increase in the accretion rate by a factor of 2–10. Although the disk becomes unstable, no other stars are formed. In the case of our 100 and 200 M {sub ⊙} simulations, the star becomes highly super-Eddington and begins to drive bipolar outflow cavities that expand outwards. These radiatively driven bubbles appear stable, and appear to be channeling gas back onto the protostellar accretion disk. Accretion proceeds strongly through the disk. After 81.4 kyr of evolution, our 30 M {sub ⊙} simulation shows a star with a mass of 5.48 M {sub ⊙} and a disk of mass 3.3 M {sub ⊙}, while our 100 M {sub ⊙} simulation forms a 28.8 M {sub ⊙} mass star with a 15.8 M {sub ⊙} disk over the course of 41.6 kyr, and our 200 M {sub ⊙} simulation forms a 43.7 M {sub ⊙} star with an 18 M {sub ⊙} disk in 21.9 kyr. In the absence of magnetic fields or other forms of feedback, the masses of the stars in our simulation do not appear to be limited by their own luminosities.

  12. Warm Debris Disks from WISE

    Science.gov (United States)

    Padgett, Deborah L.

    2011-01-01

    "The Wide Field Infrared Survey Explorer (WISE) has just completed a sensitive all-sky survey in photometric bands at 3.4, 4.6, 12, and 22 microns. We report on a preliminary investigation of main sequence Hipparcos and Tycho catalog stars with 22 micron emission in excess of photospheric levels. This warm excess emission traces material in the circumstellar region likely to host terrestrial planets and is preferentially found in young systems with ages warm debris disk candidates are detected among FGK stars and a similar number of A stars within 120 pc. We are in the process of obtaining spectra to determine spectral types and activity level of these stars and are using HST, Herschel and Keck to characterize the dust, multiplicity, and substellar companions of these systems. In this contribution, we will discuss source selection methods and individual examples from among the WISE debris disk candidates. "

  13. Next Generation Wind Turbine

    Energy Technology Data Exchange (ETDEWEB)

    Cheraghi, S. Hossein [Western New England Univ., Springfield, MA (United States); Madden, Frank [FloDesign Wind Turbine Corp., Waltham, MA (United States)

    2012-09-01

    The goal of this collaborative effort between Western New England University's College of Engineering and FloDesign Wind Turbine (FDWT) Corporation to wok on a novel areodynamic concept that could potentially lead to the next generation of wind turbines. Analytical studies and early scale model tests of FDWT's Mixer/Ejector Wind Turbine (MEWT) concept, which exploits jet-age advanced fluid dynamics, indicate that the concept has the potential to significantly reduce the cost of electricity over conventional Horizontal Axis Wind Turbines while reducing land usage. This project involved the design, fabrication, and wind tunnel testing of components of MEWT to provide the research and engineering data necessary to validate the design iterations and optimize system performance. Based on these tests, a scale model prototype called Briza was designed, fabricated, installed and tested on a portable tower to investigate and improve the design system in real world conditions. The results of these scale prototype efforts were very promising and have contributed significantly to FDWT's ongoing development of a product scale wind turbine for deployment in multiple locations around the U.S. This research was mutually beneficial to Western New England University, FDWT, and the DOE by utilizing over 30 student interns and a number of faculty in all efforts. It brought real-world wind turbine experience into the classroom to further enhance the Green Engineering Program at WNEU. It also provided on-the-job training to many students, improving their future employment opportunities, while also providing valuable information to further advance FDWT's mixer-ejector wind turbine technology, creating opportunities for future project innovation and job creation.

  14. Cross-flow turbines: physical and numerical model studies towards improved array simulations

    Science.gov (United States)

    Wosnik, M.; Bachant, P.

    2015-12-01

    Cross-flow, or vertical-axis turbines, show potential in marine hydrokinetic (MHK) and wind energy applications. As turbine designs mature, the research focus is shifting from individual devices towards improving turbine array layouts for maximizing overall power output, i.e., minimizing wake interference for axial-flow turbines, or taking advantage of constructive wake interaction for cross-flow turbines. Numerical simulations are generally better suited to explore the turbine array design parameter space, as physical model studies of large arrays at large model scale would be expensive. However, since the computing power available today is not sufficient to conduct simulations of the flow in and around large arrays of turbines with fully resolved turbine geometries, the turbines' interaction with the energy resource needs to be parameterized, or modeled. Most models in use today, e.g. actuator disk, are not able to predict the unique wake structure generated by cross-flow turbines. Experiments were carried out using a high-resolution turbine test bed in a large cross-section tow tank, designed to achieve sufficiently high Reynolds numbers for the results to be Reynolds number independent with respect to turbine performance and wake statistics, such that they can be reliably extrapolated to full scale and used for model validation. To improve parameterization in array simulations, an actuator line model (ALM) was developed to provide a computationally feasible method for simulating full turbine arrays inside Navier--Stokes models. The ALM predicts turbine loading with the blade element method combined with sub-models for dynamic stall and flow curvature. The open-source software is written as an extension library for the OpenFOAM CFD package, which allows the ALM body force to be applied to their standard RANS and LES solvers. Turbine forcing is also applied to volume of fluid (VOF) models, e.g., for predicting free surface effects on submerged MHK devices. An

  15. Development of superalloys for 1700 C ultra-efficient gas turbines

    Energy Technology Data Exchange (ETDEWEB)

    Harada, Hiroshi [National Institute for Materials Science, Tsukuba, Ibaraki (Japan). High Temperature Materials Center

    2010-07-01

    Mitigation of global warming is one of the most outstanding issues for the humankind. The Japanese government announced that it will reduce its greenhouse gas emissions by 25% from the 1990 level by 2020 as a medium-term goal. One of the promising approaches to achieving this is to improve the efficiency of thermal power plants emitting one-third of total CO{sub 2} gas in Japan. The key to improving the thermal efficiency is high temperature materials with excellent temperature capabilities allowing higher inlet gas temperatures. In this context, new single crystal superalloys for turbine blades and vanes, new coatings and turbine disk superalloys have been successfully developed for various gas turbine applications, typically 1700 C ultra-efficient gas turbines for next generation combine cycle power plants. (orig.)

  16. MIT miniaturized disk bend test

    International Nuclear Information System (INIS)

    Harling, O.K.; Lee, M.; Sohn, D.S.; Kohse, G.; Lau, C.W.

    1983-01-01

    A miniaturized disk bend test (MDBT) using transmission electron microscopy specimens for the determination of various mechanical properties is being developed at MIT. Recent progress in obtaining strengths and ductilities of highly irradiated metal alloys is reviewed. Other mechanical properties can also be obtained using the MDBT approach. Progress in fatigue testing and in determination of the ductile-to-brittle transition temperature is reviewed briefly. 11 figures

  17. Fullerenes and disk-fullerenes

    International Nuclear Information System (INIS)

    Deza, M; Dutour Sikirić, M; Shtogrin, M I

    2013-01-01

    A geometric fullerene, or simply a fullerene, is the surface of a simple closed convex 3-dimensional polyhedron with only 5- and 6-gonal faces. Fullerenes are geometric models for chemical fullerenes, which form an important class of organic molecules. These molecules have been studied intensively in chemistry, physics, crystallography, and so on, and their study has led to the appearance of a vast literature on fullerenes in mathematical chemistry and combinatorial and applied geometry. In particular, several generalizations of the notion of a fullerene have been given, aiming at various applications. Here a new generalization of this notion is proposed: an n-disk-fullerene. It is obtained from the surface of a closed convex 3-dimensional polyhedron which has one n-gonal face and all other faces 5- and 6-gonal, by removing the n-gonal face. Only 5- and 6-disk-fullerenes correspond to geometric fullerenes. The notion of a geometric fullerene is therefore generalized from spheres to compact simply connected two-dimensional manifolds with boundary. A two-dimensional surface is said to be unshrinkable if it does not contain belts, that is, simple cycles consisting of 6-gons each of which has two neighbours adjacent at a pair of opposite edges. Shrinkability of fullerenes and n-disk-fullerenes is investigated. Bibliography: 87 titles

  18. A Pulsar and a Disk

    Science.gov (United States)

    Kohler, Susanna

    2016-07-01

    Recent, unusual X-ray observations from our galactic neighbor, the Small Magellanic Cloud, have led to an interesting model for SXP 214, a pulsar in a binary star system.Artists illustration of the magnetic field lines of a pulsar, a highly magnetized, rotating neutron star. [NASA]An Intriguing BinaryAn X-ray pulsar is a magnetized, rotating neutron star in a binary system with a stellar companion. Material is fed from the companion onto the neutron star, channeled by the objects magnetic fields onto a hotspot thats millions of degrees. This hotspot rotating past our line of sight is what produces the pulsations that we observe from X-ray pulsars.Located in the Small Magellanic Cloud, SXP 214 is a transient X-ray pulsar in a binary with a Be-type star. This star is spinning so quickly that material is thrown off of it to form a circumstellar disk.Recently, a team of authors led by JaeSub Hong (Harvard-Smithsonian Center for Astrophysics) have presented new Chandra X-ray observations of SXP 214, tracking it for 50 ks (~14 hours) in January 2013. These observations reveal some very unexpected behavior for this pulsar.X-ray PuzzleThe energy distribution of the X-ray emission from SXP 214 over time. Dark shades or blue colors indicate high counts, and light shades or yellow colors indicate low counts. Lower-energy X-ray emission appeared only later, after about 20 ks. [Hong et al. 2016]Three interesting pieces of information came from the Chandra observations:SXP 214s rotation period was measured to be 211.5 s an increase in the spin rate since the discovery measurement of a 214-second period. Pulsars usually spin down as they lose angular momentum over time so what caused this one to spin up?Its overall X-ray luminosity steadily increased over the 50 ks of observations.Its spectrum became gradually softer (lower energy) over time; in the first 20 ks, the spectrum only consisted of hard X-ray photons above 3 keV, but after 20 ks, softer X-ray photons below 2 ke

  19. Fullerenes and disk-fullerenes

    Science.gov (United States)

    Deza, M.; Dutour Sikirić, M.; Shtogrin, M. I.

    2013-08-01

    A geometric fullerene, or simply a fullerene, is the surface of a simple closed convex 3-dimensional polyhedron with only 5- and 6-gonal faces. Fullerenes are geometric models for chemical fullerenes, which form an important class of organic molecules. These molecules have been studied intensively in chemistry, physics, crystallography, and so on, and their study has led to the appearance of a vast literature on fullerenes in mathematical chemistry and combinatorial and applied geometry. In particular, several generalizations of the notion of a fullerene have been given, aiming at various applications. Here a new generalization of this notion is proposed: an n-disk-fullerene. It is obtained from the surface of a closed convex 3-dimensional polyhedron which has one n-gonal face and all other faces 5- and 6-gonal, by removing the n-gonal face. Only 5- and 6-disk-fullerenes correspond to geometric fullerenes. The notion of a geometric fullerene is therefore generalized from spheres to compact simply connected two-dimensional manifolds with boundary. A two-dimensional surface is said to be unshrinkable if it does not contain belts, that is, simple cycles consisting of 6-gons each of which has two neighbours adjacent at a pair of opposite edges. Shrinkability of fullerenes and n-disk-fullerenes is investigated. Bibliography: 87 titles.

  20. Oral cavity eumycetoma

    Directory of Open Access Journals (Sweden)

    Gisele Alborghetti Nai

    2011-06-01

    Full Text Available Mycetoma is a pathological process in which eumycotic (fungal or actinomycotic causative agents from exogenous source produce grains. It is a localized chronic and deforming infectious disease of subcutaneous tissue, skin and bones. We report the first case of eumycetoma of the oral cavity in world literature. CASE REPORT: A 43-year-old male patient, complaining of swelling and fistula in the hard palate. On examination, swelling of the anterior and middle hard palate, with fistula draining a dark liquid was observed. The panoramic radiograph showed extensive radiolucent area involving the region of teeth 21-26 and the computerized tomography showed communication with the nasal cavity, suggesting the diagnosis of periapical cyst. Surgery was performed to remove the lesion. Histopathological examination revealed purulent material with characteristic grain. Gram staining for bacteria was negative and Grocott-Gomori staining for the detection of fungi was positive, concluding the diagnosis of eumycetoma. The patient was treated with ketoconazole for nine months, and was considered cured at the end of treatment. CONCLUSION: Histopathological examination, using histochemical staining, and direct microscopic grains examination can provide the distinction between eumycetoma and actinomycetoma accurately.

  1. Gas turbine engine turbine blade damaging estimate in maintenance

    Directory of Open Access Journals (Sweden)

    Ель-Хожайрі Хусейн

    2004-01-01

    Full Text Available  The factors determining character and intensity of corrosive damages of gas turbine blades are analyzed in the article. The classification of detrimental impurities polluting gas turbine airflow duct and injuring blade erosion damages are given. Common features of the method of turbine blade corrosive damage estimation are shown in the article.

  2. Cryostat for TRISTAN superconducting cavity

    International Nuclear Information System (INIS)

    Mitsunobu, S.; Furuya, T.; Hara, K.

    1990-01-01

    Superconducting cavities generate rather high heat load of hundreds watts in one cryostat and have high sensitivity for pressure. We adopted usual pool-boiling type cooling for its stable pressure operation. Two 5-cell Nb cavities were installed in one flange type cryostat. Tuning mechanics actuated by a pulse-motor and a Piezo-electric element are set at outside of vacuum end flange. The design and performance of the cryostat for TRISTAN superconducting cavities are described. (author)

  3. Superconducting Radio-Frequency Cavities

    Science.gov (United States)

    Padamsee, Hasan S.

    2014-10-01

    Superconducting cavities have been operating routinely in a variety of accelerators with a range of demanding applications. With the success of completed projects, niobium cavities have become an enabling technology, offering upgrade paths for existing facilities and pushing frontier accelerators for nuclear physics, high-energy physics, materials science, and the life sciences. With continued progress in basic understanding of radio-frequency superconductivity, the performance of cavities has steadily improved to approach theoretical capabilities.

  4. Middle ear cavity morphology is consistent with an aquatic origin for testudines.

    Directory of Open Access Journals (Sweden)

    Katie L Willis

    Full Text Available The position of testudines in vertebrate phylogeny is being re-evaluated. At present, testudine morphological and molecular data conflict when reconstructing phylogenetic relationships. Complicating matters, the ecological niche of stem testudines is ambiguous. To understand how turtles have evolved to hear in different environments, we examined middle ear morphology and scaling in most extant families, as well as some extinct species, using 3-dimensional reconstructions from micro magnetic resonance (MR and submillimeter computed tomography (CT scans. All families of testudines exhibited a similar shape of the bony structure of the middle ear cavity, with the tympanic disk located on the rostrolateral edge of the cavity. Sea Turtles have additional soft tissue that fills the middle ear cavity to varying degrees. When the middle ear cavity is modeled as an air-filled sphere of the same volume resonating in an underwater sound field, the calculated resonances for the volumes of the middle ear cavities largely fell within testudine hearing ranges. Although there were some differences in morphology, there were no statistically significant differences in the scaling of the volume of the bony middle ear cavity with head size among groups when categorized by phylogeny and ecology. Because the cavity is predicted to resonate underwater within the testudine hearing range, the data support the hypothesis of an aquatic origin for testudines, and function of the middle ear cavity in underwater sound detection.

  5. Steam exit flow design for aft cavities of an airfoil

    Science.gov (United States)

    Storey, James Michael; Tesh, Stephen William

    2002-01-01

    Turbine stator vane segments have inner and outer walls with vanes extending therebetween. The inner and outer walls have impingement plates. Steam flowing into the outer wall passes through the impingement plate for impingement cooling of the outer wall surface. The spent impingement steam flows into cavities of the vane having inserts for impingement cooling the walls of the vane. The steam passes into the inner wall and through the impingement plate for impingement cooling of the inner wall surface and for return through return cavities having inserts for impingement cooling of the vane surfaces. A skirt or flange structure is provided for shielding the steam cooling impingement holes adjacent the inner wall aerofoil fillet region of the nozzle from the steam flow exiting the aft nozzle cavities. Moreover, the gap between the flash rib boss and the cavity insert is controlled to minimize the flow of post impingement cooling media therebetween. This substantially confines outflow to that exiting via the return channels, thus furthermore minimizing flow in the vicinity of the aerofoil fillet region that may adversely affect impingement cooling thereof.

  6. Wind turbine noise diagnostics

    International Nuclear Information System (INIS)

    Richarz, W.; Richarz, H.

    2009-01-01

    This presentation proposed a self-consistent model for broad-band noise emitted from modern wind turbines. The simple source model was consistent with the physics of sound generation and considered the unique features of wind turbines. Although the acoustics of wind turbines are similar to those of conventional propellers, the dimensions of wind turbines pose unique challenges in diagnosing noise emission. The general features of the sound field were deduced. Source motion and source directivity appear to be responsible for amplitude variations. The amplitude modulation is likely to make wind-turbine noise more audible, and may be partly responsible for annoyance that has been reported in the literature. Acoustic array data suggests that broad-band noise is emitted predominantly during the downward sweep of each rotor blade. Source motion and source directivity account for the observed pattern. Rotor-tower interaction effects are of lesser importance. Predicted amplitude modulation ranges from 1 dB to 6dB. 2 refs., 9 figs.

  7. Deflector plants turbine aeration

    International Nuclear Information System (INIS)

    Miller, D.E.; Sheppard, A.R.; Widener, D.W.

    1991-01-01

    Water quality requirements have become a focal point in recent re-licensing of hydroelectric projects. The Federal Energy Regulatory Commission has significantly increased the relevance of license conditions to insure that turbine discharges meet state or other specific criteria for dissolved oxygen (D.O.). Due to naturally occurring depletion of D.O. at increased depths in large reservoirs, water withdrawn from this strata may result in unacceptably low levels of D.O. Different researchers have evaluated various methods of improving D.O. content in hydro turbine discharges, including; diffusers, weirs, oxygen injection, and variations of turbine venting. The authors describe an approach called deflector plate turbine aeration. This computer based, engineered approach allows systems to be evaluated, designed, and installed with predictable performance and costs. Many experts in this field now agree that, to the extent practical, turbine venting offers the most dependable, maintenance free, and cost effective solution to the low D.O. problem. The approach presented in this paper has resulted in proven results

  8. Floating wind turbine system

    Science.gov (United States)

    Viterna, Larry A. (Inventor)

    2009-01-01

    A floating wind turbine system with a tower structure that includes at least one stability arm extending therefrom and that is anchored to the sea floor with a rotatable position retention device that facilitates deep water installations. Variable buoyancy for the wind turbine system is provided by buoyancy chambers that are integral to the tower itself as well as the stability arm. Pumps are included for adjusting the buoyancy as an aid in system transport, installation, repair and removal. The wind turbine rotor is located downwind of the tower structure to allow the wind turbine to follow the wind direction without an active yaw drive system. The support tower and stability arm structure is designed to balance tension in the tether with buoyancy, gravity and wind forces in such a way that the top of the support tower leans downwind, providing a large clearance between the support tower and the rotor blade tips. This large clearance facilitates the use of articulated rotor hubs to reduced damaging structural dynamic loads. Major components of the turbine can be assembled at the shore and transported to an offshore installation site.

  9. CEBAF: Accelerating cavities look good

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1990-09-15

    The first assembled pairs of superconducting accelerating cavities from German supplier Interatom for the Continuous Electron Beam Accelerator Facility, Newport News, Virginia, have exceeded performance specifications.

  10. CEBAF: Accelerating cavities look good

    International Nuclear Information System (INIS)

    Anon.

    1990-01-01

    The first assembled pairs of superconducting accelerating cavities from German supplier Interatom for the Continuous Electron Beam Accelerator Facility, Newport News, Virginia, have exceeded performance specifications

  11. Wind turbine control and monitoring

    CERN Document Server

    Luo, Ningsu; Acho, Leonardo

    2014-01-01

    Maximizing reader insights into the latest technical developments and trends involving wind turbine control and monitoring, fault diagnosis, and wind power systems, 'Wind Turbine Control and Monitoring' presents an accessible and straightforward introduction to wind turbines, but also includes an in-depth analysis incorporating illustrations, tables and examples on how to use wind turbine modeling and simulation software.   Featuring analysis from leading experts and researchers in the field, the book provides new understanding, methodologies and algorithms of control and monitoring, comput

  12. OT1_ipascucc_1: Understanding the Origin of Transition Disks via Disk Mass Measurements

    Science.gov (United States)

    Pascucci, I.

    2010-07-01

    Transition disks are a distinguished group of few Myr-old systems caught in the phase of dispersing their inner dust disk. Three different processes have been proposed to explain this inside-out clearing: grain growth, photoevaporation driven by the central star, and dynamical clearing by a forming giant planet. Which of these processes lead to a transition disk? Distinguishing between them requires the combined knowledge of stellar accretion rates and disk masses. We propose here to use 43.8 hours of PACS spectroscopy to detect the [OI] 63 micron emission line from a sample of 21 well-known transition disks with measured mass accretion rates. We will use this line, in combination with ancillary CO millimeter lines, to measure their gas disk mass. Because gas dominates the mass of protoplanetary disks our approach and choice of lines will enable us to trace the bulk of the disk mass that resides beyond tens of AU from young stars. Our program will quadruple the number of transition disks currently observed with Herschel in this setting and for which disk masses can be measured. We will then place the transition and the ~100 classical/non-transition disks of similar age (from the Herschel KP "Gas in Protoplanetary Systems") in the mass accretion rate-disk mass diagram with two main goals: 1) reveal which gaps have been created by grain growth, photoevaporation, or giant planet formation and 2) from the statistics, determine the main disk dispersal mechanism leading to a transition disk.

  13. Flow visualization system for wind turbines without blades applied to micro reactors; Sistema de visualização de escoamento para turbinas sem lâminas aplicada a microrreatores

    Energy Technology Data Exchange (ETDEWEB)

    Santos, G.S.B., E-mail: siqueira.gsb@gmail.com [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), São José dos Campos, SP (Brazil); Guimarães, L.N.F. [Instituto de Estudos Avançados (IEAv), São José dos Campos, SP (Brazil). Departamento de Ciência e Tecnologia Aeroespacial; Placco, G.M. [Instituto Tecnológico de Aeronáutica (PG/CTE/ITA), São José dos Campos, SP (Brazil). Departamento de Ciência e Tecnologia Aeroespacial

    2017-07-01

    Flow visualization systems is a tool used in science and industry for characterization of projects that operate with drainage. This work presents the design and construction of a flow visualization system for passive turbines used in advanced fast micro reactors. In the system were generated images where it is possible to see the supersonic and transonic flow through the turbine disks. A test bench was assembled to generate images of the interior of the turbine where the flow is supersonic, allowing the study of the behavior of the boundary layer between disks. It is necessary to characterize the boundary layer of this type of turbine because its operation occurs in the transfer of kinetic energy between the fluid and the disks. The images generated, as well as their analyzes are presented as a result of this work.

  14. Complex Spiral Structure in the HD 100546 Transitional Disk as Revealed by GPI and MagAO

    Energy Technology Data Exchange (ETDEWEB)

    Follette, Katherine B.; Macintosh, Bruce; Mullen, Wyatt; Bailey, Vanessa P. [Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics, Stanford University, Stanford, CA, 94305 (United States); Rameau, Julien [Institut de Recherche sur les Exoplanètes, Départment de Physique, Université de Montréal, Montréal QC H3C 3J7 (Canada); Dong, Ruobing; Close, Laird M.; Males, Jared R.; Morzinski, Katie M. [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Pueyo, Laurent; Perrin, Marshall [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Duchêne, Gaspard; Fung, Jeffrey; Wang, Jason [Astronomy Department, University of California, Berkeley, Berkeley CA 94720 (United States); Leonard, Clare; Spiro, Elijah [Physics and Astronomy Department, Amherst College, 21 Merrill Science Drive, Amherst, MA 01002 (United States); Marois, Christian [National Research Council of Canada Herzberg, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada); Millar-Blanchaer, Maxwell A. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91125 (United States); Ammons, S. Mark [Lawrence Livermore National Laboratory, Livermore, CA 94551 (United States); Barman, Travis [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States); and others

    2017-06-01

    We present optical and near-infrared high-contrast images of the transitional disk HD 100546 taken with the Magellan Adaptive Optics system (MagAO) and the Gemini Planet Imager (GPI). GPI data include both polarized intensity and total intensity imagery, and MagAO data are taken in Simultaneous Differential Imaging mode at H α . The new GPI H -band total intensity data represent a significant enhancement in sensitivity and field rotation compared to previous data sets and enable a detailed exploration of substructure in the disk. The data are processed with a variety of differential imaging techniques (polarized, angular, reference, and simultaneous differential imaging) in an attempt to identify the disk structures that are most consistent across wavelengths, processing techniques, and algorithmic parameters. The inner disk cavity at 15 au is clearly resolved in multiple data sets, as are a variety of spiral features. While the cavity and spiral structures are identified at levels significantly distinct from the neighboring regions of the disk under several algorithms and with a range of algorithmic parameters, emission at the location of HD 100546 “ c ” varies from point-like under aggressive algorithmic parameters to a smooth continuous structure with conservative parameters, and is consistent with disk emission. Features identified in the HD 100546 disk bear qualitative similarity to computational models of a moderately inclined two-armed spiral disk, where projection effects and wrapping of the spiral arms around the star result in a number of truncated spiral features in forward-modeled images.

  15. ALMA REVEALS THE ANATOMY OF THE mm-SIZED DUST AND MOLECULAR GAS IN THE HD 97048 DISK

    Energy Technology Data Exchange (ETDEWEB)

    Walsh, Catherine; Maud, Luke T. [Leiden Observatory, Leiden University, P.O. Box 9531, 2300 RA Leiden (Netherlands); Juhász, Attila [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Meeus, Gwendolyn [Departamento de Física Teórica, Universidad Autonoma de Madrid, Campus Cantoblanco, E-28049 Madrid (Spain); Dent, William R. F. [Joint ALMA Observatory (JAO), Alonso de Córdova 3107, Vitacura, Santiago (Chile); Aikawa, Yuri [Center for Computer Sciences, University of Tsukuba, 305-8577 Tsukuba (Japan); Millar, Tom J. [School of Mathematics and Physics, Queen’s University Belfast, University Road, Belfast BT7 1NN (United Kingdom); Nomura, Hideko, E-mail: cwalsh@strw.leidenuniv.nl, E-mail: c.walsh1@leeds.ac.uk [Department of Earth and Planetary Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, 152-8551 Tokyo (Japan)

    2016-11-10

    Transitional disks show a lack of excess emission at infrared wavelengths due to a large dust cavity, that is often corroborated by spatially resolved observations at ∼ mm wavelengths. We present the first spatially resolved ∼ mm-wavelength images of the disk around the Herbig Ae/Be star, HD 97048. Scattered light images show that the disk extends to ≈640 au. ALMA data reveal a circular-symmetric dusty disk extending to ≈350 au, and a molecular disk traced in CO J = 3-2 emission, extending to ≈750 au. The CO emission arises from a flared layer with an opening angle ≈30°–40°. HD 97048 is another source for which the large (∼ mm-sized) dust grains are more centrally concentrated than the small (∼ μ m-sized) grains and molecular gas, likely due to radial drift. The images and visibility data modeling suggest a decrement in continuum emission within ≈50 au, consistent with the cavity size determined from mid-infrared imaging (34 ± 4 au). The extracted continuum intensity profiles show ring-like structures with peaks at ≈50, 150, and 300 au, with associated gaps at ≈100 and 250 au. This structure should be confirmed in higher-resolution images (FWHM ≈ 10–20 au). These data confirm the classification of HD 97048 as a transitional disk that also possesses multiple ring-like structures in the dust continuum emission. Additional data are required at multiple and well-separated frequencies to fully characterize the disk structure, and thereby constrain the mechanism(s) responsible for sculpting the HD 97048 disk.

  16. ALMA Reveals the Anatomy of the mm-sized Dust and Molecular Gas in the HD 97048 Disk

    Science.gov (United States)

    Walsh, Catherine; Juhász, Attila; Meeus, Gwendolyn; Dent, William R. F.; Maud, Luke T.; Aikawa, Yuri; Millar, Tom J.; Nomura, Hideko

    2016-11-01

    Transitional disks show a lack of excess emission at infrared wavelengths due to a large dust cavity, that is often corroborated by spatially resolved observations at ˜ mm wavelengths. We present the first spatially resolved ˜ mm-wavelength images of the disk around the Herbig Ae/Be star, HD 97048. Scattered light images show that the disk extends to ≈640 au. ALMA data reveal a circular-symmetric dusty disk extending to ≈350 au, and a molecular disk traced in CO J = 3-2 emission, extending to ≈750 au. The CO emission arises from a flared layer with an opening angle ≈30°-40°. HD 97048 is another source for which the large (˜ mm-sized) dust grains are more centrally concentrated than the small (˜μm-sized) grains and molecular gas, likely due to radial drift. The images and visibility data modeling suggest a decrement in continuum emission within ≈50 au, consistent with the cavity size determined from mid-infrared imaging (34 ± 4 au). The extracted continuum intensity profiles show ring-like structures with peaks at ≈50, 150, and 300 au, with associated gaps at ≈100 and 250 au. This structure should be confirmed in higher-resolution images (FWHM ≈ 10-20 au). These data confirm the classification of HD 97048 as a transitional disk that also possesses multiple ring-like structures in the dust continuum emission. Additional data are required at multiple and well-separated frequencies to fully characterize the disk structure, and thereby constrain the mechanism(s) responsible for sculpting the HD 97048 disk.

  17. ALMA REVEALS THE ANATOMY OF THE mm-SIZED DUST AND MOLECULAR GAS IN THE HD 97048 DISK

    International Nuclear Information System (INIS)

    Walsh, Catherine; Maud, Luke T.; Juhász, Attila; Meeus, Gwendolyn; Dent, William R. F.; Aikawa, Yuri; Millar, Tom J.; Nomura, Hideko

    2016-01-01

    Transitional disks show a lack of excess emission at infrared wavelengths due to a large dust cavity, that is often corroborated by spatially resolved observations at ∼ mm wavelengths. We present the first spatially resolved ∼ mm-wavelength images of the disk around the Herbig Ae/Be star, HD 97048. Scattered light images show that the disk extends to ≈640 au. ALMA data reveal a circular-symmetric dusty disk extending to ≈350 au, and a molecular disk traced in CO J = 3-2 emission, extending to ≈750 au. The CO emission arises from a flared layer with an opening angle ≈30°–40°. HD 97048 is another source for which the large (∼ mm-sized) dust grains are more centrally concentrated than the small (∼ μ m-sized) grains and molecular gas, likely due to radial drift. The images and visibility data modeling suggest a decrement in continuum emission within ≈50 au, consistent with the cavity size determined from mid-infrared imaging (34 ± 4 au). The extracted continuum intensity profiles show ring-like structures with peaks at ≈50, 150, and 300 au, with associated gaps at ≈100 and 250 au. This structure should be confirmed in higher-resolution images (FWHM ≈ 10–20 au). These data confirm the classification of HD 97048 as a transitional disk that also possesses multiple ring-like structures in the dust continuum emission. Additional data are required at multiple and well-separated frequencies to fully characterize the disk structure, and thereby constrain the mechanism(s) responsible for sculpting the HD 97048 disk.

  18. Wind Turbine With Concentric Ducts

    Science.gov (United States)

    Muhonen, A. J.

    1983-01-01

    Wind Turbine device is relatively compact and efficient. Converging inner and outer ducts increase pressure difference across blades of wind turbine. Turbine shaft drives alternator housed inside exit cone. Suitable for installation on such existing structures as water towers, barns, houses, and commercial buildings.

  19. Wind turbine spoiler

    Science.gov (United States)

    Sullivan, W.N.

    An aerodynamic spoiler system for a vertical axis wind turbine includes spoilers on the blades initially stored near the rotor axis to minimize drag. A solenoid latch adjacent the central support tower releases the spoilers and centrifugal force causes the spoilers to move up the turbine blades away from the rotor axis, thereby producing a braking effect and actual slowing of the associated wind turbine, if desired. The spoiler system can also be used as an infinitely variable power control by regulated movement of the spoilers on the blades over the range between the undeployed and fully deployed positions. This is done by the use of a suitable powered reel and cable located at the rotor tower to move the spoilers.

  20. Steam turbine installations

    International Nuclear Information System (INIS)

    Bainbridge, A.

    1976-01-01

    The object of the arrangement described is to enable raising steam for driving steam turbines in a way suited to operating with liquid metals, such as Na, as heat transfer medium. A preheated water feed, in heat transfer relationship with the liquid metals, is passed through evaporator and superheater stages, and the superheated steam is supplied to the highest pressure stage of the steam turbine arrangement. Steam extracted intermediate the evaporator and superheater stages is employed to provide reheat for the lower pressure stage of the steam turbine. Only a major portion of the preheated water feed may be evaporated and this portion separated and supplied to the superheater stage. The feature of 'steam to steam' reheat avoids a second liquid metal heat transfer and hence represents a simplification. It also reduces the hazard associated with possible steam-liquid metal contact. (U.K.)

  1. Hydro turbines: An introduction

    International Nuclear Information System (INIS)

    Gordon, J.L.

    1993-01-01

    The various types of hydraulic turbines currently used in hydroelectric power plants are described. The descriptions are intended for use by non-engineers who are concerned with fish passage and fish mortality at a hydro power facility. Terminology used in the hydro industry is explained. Since the extent of cavitation is one of the factors affecting mortality rates of fish passing through hydraulic turbines, an equation is introduced which measures the extent of cavitation likely to be experienced in a turbine. An example of how the cavitation index can be calculated is provided for two typical power plants. The relation between certain parameters of power plant operation and the extent of cavitation, and therefore of fish mortality, is illustrated. 2 refs., 14 figs

  2. Variable stator radial turbine

    Science.gov (United States)

    Rogo, C.; Hajek, T.; Chen, A. G.

    1984-01-01

    A radial turbine stage with a variable area nozzle was investigated. A high work capacity turbine design with a known high performance base was modified to accept a fixed vane stagger angle moveable sidewall nozzle. The nozzle area was varied by moving the forward and rearward sidewalls. Diffusing and accelerating rotor inlet ramps were evaluated in combinations with hub and shroud rotor exit rings. Performance of contoured sidewalls and the location of the sidewall split line with respect to the rotor inlet was compared to the baseline. Performance and rotor exit survey data are presented for 31 different geometries. Detail survey data at the nozzle exit are given in contour plot format for five configurations. A data base is provided for a variable geometry concept that is a viable alternative to the more common pivoted vane variable geometry radial turbine.

  3. Noise from wind turbines

    International Nuclear Information System (INIS)

    Andersen, B.; Jakobsen, J.

    1992-11-01

    Based on a previous project concerning the calculation of the amount of noise emanating from wind turbine arrays, this one examines the subject further by investigating whether there could be significant differences in the amount of noise made by individual wind turbines in an array, and whether the noise is transmitted in varying directions - so that when it is carried in the same direction as the wind blows it would appear to be louder. The aim was also to determine whether the previously used method of calculation lacked precision. It was found that differences in noise niveaux related to individual wind turbines were insignificant and that noise was not so loud when it was not borne in the direction of the wind. It was necessary to change the method of calculation as reckoning should include the influence of the terrain, wind velocity and distance. The measuring and calculation methods are exemplified and the resulting measurements are presented in detail. (AB)

  4. Aeroservoelasticity of Wind Turbines

    DEFF Research Database (Denmark)

    Kallesøe, Bjarne Skovmose

    2007-01-01

    This thesis deals with the fundamental aeroelastic interaction between structural motion, Pitch action and control for a wind turbine blade. As wind turbines become larger, the interaction between pitch action, blade motion, aerodynamic forces, and control become even more important to understand......, and furthermore linear and therefore suitable for control design. The development of the primary aeroelastic blade model is divided into four steps: 1) Nonlinear partial differential equations (PDEs) of structural blade motion are derived together with equations of pitch action and rotor speed; the individual...... to a 2D blade section model, and it can be used instead of this in many applications, giving a transparent connection to a real wind turbine blade. In this work the aeroelastic blade model is used to analyze interaction between pitch action, blade motion and wind speed variations. Furthermore the model...

  5. Wind Turbine Acoustics

    Science.gov (United States)

    Hubbard, Harvey H.; Shepherd, Kevin P.

    2009-01-01

    Wind turbine generators, ranging in size from a few kilowatts to several megawatts, are producing electricity both singly and in wind power stations that encompass hundreds of machines. Many installations are in uninhabited areas far from established residences, and therefore there are no apparent environmental impacts in terms of noise. There is, however, the potential for situations in which the radiated noise can be heard by residents of adjacent neighborhoods, particularly those neighborhoods with low ambient noise levels. A widely publicized incident of this nature occurred with the operation of the experimental Mod-1 2-MW wind turbine, which is described in detail elsewhere. Pioneering studies which were conducted at the Mod-1 site on the causes and remedies of noise from wind turbines form the foundation of much of the technology described in this chapter.

  6. Micro turbines on gas

    International Nuclear Information System (INIS)

    Kotevski, Darko

    2003-01-01

    Microturbines are small gas turbine engines that drive a generator with sizes ranging from 30-350 kW. Although similar in function to bigger gas turbines, their simple radial flow turbine and high-speed generator offer better performance, greater reliability, longer service intervals, reduced maintenance lower emission and lower noise. Microturbines can generate power continuously and very economically to reduce electricity costs or they can be operated selectively for peak shaving. These benefits are further enhanced by the economics of using the microturbine's waste heat for hot water needs or other heating applications. That is why on-site microturbine power is widely used for independent production of electricity and heat in industrial and commercial facilities, hotels, hospitals, office buildings, residential buildings etc. (Original)

  7. Foundations of Black Hole Accretion Disk Theory.

    Science.gov (United States)

    Abramowicz, Marek A; Fragile, P Chris

    2013-01-01

    This review covers the main aspects of black hole accretion disk theory. We begin with the view that one of the main goals of the theory is to better understand the nature of black holes themselves. In this light we discuss how accretion disks might reveal some of the unique signatures of strong gravity: the event horizon, the innermost stable circular orbit, and the ergosphere. We then review, from a first-principles perspective, the physical processes at play in accretion disks. This leads us to the four primary accretion disk models that we review: Polish doughnuts (thick disks), Shakura-Sunyaev (thin) disks, slim disks, and advection-dominated accretion flows (ADAFs). After presenting the models we discuss issues of stability, oscillations, and jets. Following our review of the analytic work, we take a parallel approach in reviewing numerical studies of black hole accretion disks. We finish with a few select applications that highlight particular astrophysical applications: measurements of black hole mass and spin, black hole vs. neutron star accretion disks, black hole accretion disk spectral states, and quasi-periodic oscillations (QPOs).

  8. Foundations of Black Hole Accretion Disk Theory

    Directory of Open Access Journals (Sweden)

    Marek A. Abramowicz

    2013-01-01

    Full Text Available This review covers the main aspects of black hole accretion disk theory. We begin with the view that one of the main goals of the theory is to better understand the nature of black holes themselves. In this light we discuss how accretion disks might reveal some of the unique signatures of strong gravity: the event horizon, the innermost stable circular orbit, and the ergosphere. We then review, from a first-principles perspective, the physical processes at play in accretion disks. This leads us to the four primary accretion disk models that we review: Polish doughnuts (thick disks, Shakura-Sunyaev (thin disks, slim disks, and advection-dominated accretion flows (ADAFs. After presenting the models we discuss issues of stability, oscillations, and jets. Following our review of the analytic work, we take a parallel approach in reviewing numerical studies of black hole accretion disks. We finish with a few select applications that highlight particular astrophysical applications: measurements of black hole mass and spin, black hole vs. neutron star accretion disks, black hole accretion disk spectral states, and quasi-periodic oscillations (QPOs.

  9. Fast disk array for image storage

    Science.gov (United States)

    Feng, Dan; Zhu, Zhichun; Jin, Hai; Zhang, Jiangling

    1997-01-01

    A fast disk array is designed for the large continuous image storage. It includes a high speed data architecture and the technology of data striping and organization on the disk array. The high speed data path which is constructed by two dual port RAM and some control circuit is configured to transfer data between a host system and a plurality of disk drives. The bandwidth can be more than 100 MB/s if the data path based on PCI (peripheral component interconnect). The organization of data stored on the disk array is similar to RAID 4. Data are striped on a plurality of disk, and each striping unit is equal to a track. I/O instructions are performed in parallel on the disk drives. An independent disk is used to store the parity information in the fast disk array architecture. By placing the parity generation circuit directly on the SCSI (or SCSI 2) bus, the parity information can be generated on the fly. It will affect little on the data writing in parallel on the other disks. The fast disk array architecture designed in the paper can meet the demands of the image storage.

  10. Steam generators, turbines, and condensers. Volume six

    International Nuclear Information System (INIS)

    Anon.

    1986-01-01

    Volume six covers steam generators (How steam is generated, steam generation in a PWR, vertical U-tube steam generators, once-through steam generators, how much steam do steam generators make?), turbines (basic turbine principles, impulse turbines, reaction turbines, turbine stages, turbine arrangements, turbine steam flow, steam admission to turbines, turbine seals and supports, turbine oil system, generators), and condensers (need for condensers, basic condenser principles, condenser arrangements, heat transfer in condensers, air removal from condensers, circulating water system, heat loss to the circulating water system, factors affecting condenser performance, condenser auxiliaries)

  11. DUST FILTRATION BY PLANET-INDUCED GAP EDGES: IMPLICATIONS FOR TRANSITIONAL DISKS

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Zhaohuan; Dong Ruobing [Department of Astrophysical Sciences, 4 Ivy Lane, Peyton Hall, Princeton University, Princeton, NJ 08544 (United States); Nelson, Richard P. [Astronomy Unit, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom); Espaillat, Catherine [Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Hartmann, Lee, E-mail: zhzhu@astro.princeton.edu, E-mail: rdong@astro.princeton.edu, E-mail: lhartm@umich.edu, E-mail: r.p.nelson@qmul.ac.uk, E-mail: cespaillat@cfa.harvard.edu [Department of Astronomy, University of Michigan, 500 Church St., Ann Arbor, MI 48109 (United States)

    2012-08-10

    By carrying out two-dimensional two-fluid global simulations, we have studied the response of dust to gap formation by a single planet in the gaseous component of a protoplanetary disk-the so-called dust filtration mechanism. We have found that a gap opened by a giant planet at 20 AU in an {alpha} = 0.01, M-dot =10{sup -8} M{sub Sun} yr{sup -1} disk can effectively stop dust particles larger than 0.1 mm drifting inward, leaving a submillimeter (submm) dust cavity/hole. However, smaller particles are difficult to filter by a gap induced by a several M{sub J} planet due to (1) dust diffusion and (2) a high gas accretion velocity at the gap edge. Based on these simulations, an analytic model is derived to understand what size particles can be filtered by the planet-induced gap edge. We show that a dimensionless parameter T{sub s} /{alpha}, which is the ratio between the dimensionless dust stopping time and the disk viscosity parameter, is important for the dust filtration process. Finally, with our updated understanding of dust filtration, we have computed Monte Carlo radiative transfer models with variable dust size distributions to generate the spectral energy distributions of disks with gaps. By comparing with transitional disk observations (e.g., GM Aur), we have found that dust filtration alone has difficulties depleting small particles sufficiently to explain the near-IR deficit of moderate M-dot transitional disks, except under some extreme circumstances. The scenario of gap opening by multiple planets studied previously suffers the same difficulty. One possible solution is to invoke both dust filtration and dust growth in the inner disk. In this scenario, a planet-induced gap filters large dust particles in the disk, and the remaining small dust particles passing to the inner disk can grow efficiently without replenishment from fragmentation of large grains. Predictions for ALMA have also been made based on all these scenarios. We conclude that dust filtration

  12. Vibration-Based Data Used to Detect Cracks in Rotating Disks

    Science.gov (United States)

    Gyekenyesi, Andrew L.; Sawicki, Jerzy T.; Martin, Richard E.; Baaklini, George Y.

    2004-01-01

    Rotor health monitoring and online damage detection are increasingly gaining the interest of aircraft engine manufacturers. This is primarily due to the fact that there is a necessity for improved safety during operation as well as a need for lower maintenance costs. Applied techniques for the damage detection and health monitoring of rotors are essential for engine safety, reliability, and life prediction. Recently, the United States set the ambitious goal of reducing the fatal accident rate for commercial aviation by 80 percent within 10 years. In turn, NASA, in collaboration with the Federal Aviation Administration, other Federal agencies, universities, and the airline and aircraft industries, responded by developing the Aviation Safety Program. This program provides research and technology products needed to help the aerospace industry achieve their aviation safety goal. The Nondestructive Evaluation (NDE) Group of the Optical Instrumentation Technology Branch at the NASA Glenn Research Center is currently developing propulsion-system-specific technologies to detect damage prior to catastrophe under the propulsion health management task. Currently, the NDE group is assessing the feasibility of utilizing real-time vibration data to detect cracks in turbine disks. The data are obtained from radial blade-tip clearance and shaft-clearance measurements made using capacitive or eddy-current probes. The concept is based on the fact that disk cracks distort the strain field within the component. This, in turn, causes a small deformation in the disk's geometry as well as a possible change in the system's center of mass. The geometric change and the center of mass shift can be indirectly characterized by monitoring the amplitude and phase of the first harmonic (i.e., the 1 component) of the vibration data. Spin pit experiments and full-scale engine tests have been conducted while monitoring for crack growth with this detection methodology. Even so, published data are

  13. Secular Evolution in Disk Galaxies

    Science.gov (United States)

    Kormendy, John

    2013-10-01

    Self-gravitating systems evolve toward the most tightly bound configuration that is reachable via the evolution processes that are available to them. They do this by spreading -- the inner parts shrink while the outer parts expand -- provided that some physical process efficiently transports energy or angular momentum outward. The reason is that self-gravitating systems have negative specific heats. As a result, the evolution of stars, star clusters, protostellar and protoplanetary disks, black hole accretion disks and galaxy disks are fundamentally similar. How evolution proceeds then depends on the evolution processes that are available to each kind of self-gravitating system. These processes and their consequences for galaxy disks are the subjects of my lectures and of this Canary Islands Winter School. I begin with a review of the formation, growth and death of bars. Then I review the slow (`secular') rearrangement of energy, angular momentum, and mass that results from interactions between stars or gas clouds and collective phenomena such as bars, oval disks, spiral structure and triaxial dark haloes. The `existence-proof' phase of this work is largely over: we have a good heuristic understanding of how nonaxisymmetric structures rearrange disk gas into outer rings, inner rings and stuff dumped onto the centre. The results of simulations correspond closely to the morphology of barred and oval galaxies. Gas that is transported to small radii reaches high densities. Observations confirm that many barred and oval galaxies have dense central concentrations of gas and star formation. The result is to grow, on timescales of a few Gyr, dense central components that are frequently mistaken for classical (elliptical-galaxy-like) bulges but that were grown slowly out of the disk (not made rapidly by major mergers). The resulting picture of secular galaxy evolution accounts for the richness observed in galaxy structure. We can distinguish between classical and pseudo

  14. Offshore Wind Turbine Design

    DEFF Research Database (Denmark)

    Frandsen, Sten; Hansen, Erik Asp; Ibsen, Lars Bo

    2006-01-01

    Current offshore wind turbine design methods have matured to a 1st generation state, manifested in the draft of a possible standard, IEC 61400-3 (2005). It is now time to investigate the possibilities of improving existing methods. To do so in an efficient manner a clear identification of the most...... important uncertainty drivers specific for offshore wind turbine design loads is required. Describing the initial efforts in a Danish research project, the paper points to focal points for research and development. These are mainly: soil-structure interaction, improved modelling of wave loads from deep...

  15. Vertical axis wind turbines

    Science.gov (United States)

    Krivcov, Vladimir [Miass, RU; Krivospitski, Vladimir [Miass, RU; Maksimov, Vasili [Miass, RU; Halstead, Richard [Rohnert Park, CA; Grahov, Jurij [Miass, RU

    2011-03-08

    A vertical axis wind turbine is described. The wind turbine can include a top ring, a middle ring and a lower ring, wherein a plurality of vertical airfoils are disposed between the rings. For example, three vertical airfoils can be attached between the upper ring and the middle ring. In addition, three more vertical airfoils can be attached between the lower ring and the middle ring. When wind contacts the vertically arranged airfoils the rings begin to spin. By connecting the rings to a center pole which spins an alternator, electricity can be generated from wind.

  16. Vertical axis wind turbine

    International Nuclear Information System (INIS)

    Obretenov, V.; Tsalov, T.; Chakarov, T.

    2012-01-01

    In recent years, the interest in wind turbines with vertical axis noticeably increased. They have some important advantages: low cost, relatively simple structure, reliable packaging system of wind aggregate long period during which require no maintenance, low noise, independence of wind direction, etc.. The relatively low efficiency, however, makes them applicable mainly for small facilities. The work presents a methodology and software for approximately aerodynamic design of wind turbines of this type, and also analyzed the possibility of improving the efficiency of their workflow

  17. ADVANCED TURBINE SYSTEMS PROGRAM

    Energy Technology Data Exchange (ETDEWEB)

    Gregory Gaul

    2004-04-21

    Natural gas combustion turbines are rapidly becoming the primary technology of choice for generating electricity. At least half of the new generating capacity added in the US over the next twenty years will be combustion turbine systems. The Department of Energy has cosponsored with Siemens Westinghouse, a program to maintain the technology lead in gas turbine systems. The very ambitious eight year program was designed to demonstrate a highly efficient and commercially acceptable power plant, with the ability to fire a wide range of fuels. The main goal of the Advanced Turbine Systems (ATS) Program was to develop ultra-high efficiency, environmentally superior and cost effective competitive gas turbine systems for base load application in utility, independent power producer and industrial markets. Performance targets were focused on natural gas as a fuel and included: System efficiency that exceeds 60% (lower heating value basis); Less than 10 ppmv NO{sub x} emissions without the use of post combustion controls; Busbar electricity that are less than 10% of state of the art systems; Reliability-Availability-Maintainability (RAM) equivalent to current systems; Water consumption minimized to levels consistent with cost and efficiency goals; and Commercial systems by the year 2000. In a parallel effort, the program was to focus on adapting the ATS engine to coal-derived or biomass fuels. In Phase 1 of the ATS Program, preliminary investigators on different gas turbine cycles demonstrated that net plant LHV based efficiency greater than 60% was achievable. In Phase 2 the more promising cycles were evaluated in greater detail and the closed-loop steam-cooled combined cycle was selected for development because it offered the best solution with least risk for achieving the ATS Program goals for plant efficiency, emissions, cost of electricity and RAM. Phase 2 also involved conceptual ATS engine and plant design and technology developments in aerodynamics, sealing

  18. Multiple piece turbine airfoil

    Science.gov (United States)

    Kimmel, Keith D; Wilson, Jr., Jack W.

    2010-11-02

    A turbine airfoil, such as a rotor blade or a stator vane, for a gas turbine engine, the airfoil formed as a shell and spar construction with a plurality of dog bone struts each mounted within openings formed within the shell and spar to allow for relative motion between the spar and shell in the airfoil chordwise direction while also forming a seal between adjacent cooling channels. The struts provide the seal as well as prevent bulging of the shell from the spar due to the cooling air pressure.

  19. Aerodynamics of wind turbines

    CERN Document Server

    Hansen, Martin O L

    2015-01-01

    Aerodynamics of Wind Turbines is the established essential text for the fundamental solutions to efficient wind turbine design. Now in its third edition, it has been substantially updated with respect to structural dynamics and control. The new control chapter now includes details on how to design a classical pitch and torque regulator to control rotational speed and power, while the section on structural dynamics has been extended with a simplified mechanical system explaining the phenomena of forward and backward whirling modes. Readers will also benefit from a new chapter on Vertical Axis W

  20. Ceramic gas turbine shroud

    Science.gov (United States)

    Shi, Jun; Green, Kevin E.

    2014-07-22

    An example gas turbine engine shroud includes a first annular ceramic wall having an inner side for resisting high temperature turbine engine gasses and an outer side with a plurality of radial slots. A second annular metallic wall is positioned radially outwardly of and enclosing the first annular ceramic wall and has a plurality of tabs in communication with the slot of the first annular ceramic wall. The tabs of the second annular metallic wall and slots of the first annular ceramic wall are in communication such that the first annular ceramic wall and second annular metallic wall are affixed.

  1. Development of the monoblock rotor for large scale LP turbine

    International Nuclear Information System (INIS)

    Ninomiya, Satoshi; Kashiwahara, Katsuto

    1981-01-01

    One of the important points in large steam turbines is the long last stage blades. So far, rotor disks were shrink-fitted to a shaft, but recently, the operation of steam turbines requires frequent start and stop, and is subjected to frequent load variation. In order to improve the reliability of steam turbines drastically under such situation, the large rotors of one-body forging type have been demanded. Hitachi Ltd. Manufactured a large rotor of one-body forging type for trial, and in order to confirm its reliability, the rotation test simulating the temperature distribution in the operation of steam turbines was carried out. The large material must be thoroughly forged to the inner part, and the effect of heat treatment reaches to the whole body, thus the prescribed chemical composition and mechanical properties must be obtained. The material must be homogeneous and stable to the thermal effect in operation. The largest outside diameter of the rotor is about 2.5 m, the shaft length is 12 m, and the finished weight is 220 t. A 500 t ingot of Ni-Cr-Mo-V steel was used. As the results of various tests, it was confirmed that the material was clean and homogeneous, and had good mechanical properties. Also the material was sufficiently thermally stable in the heating deflection measurement. In the high speed rotation test at the actual temperature, the vibration of the rotor was very small, and the good result was obtained. (Kako, I.)

  2. Ultrasonic testing of installed low-pressure turbine shafts

    International Nuclear Information System (INIS)

    Hildmann, I.; Voelker, J.; Ewald, J.

    1987-01-01

    Transverse defects in the admission area of double-flow LP turbine shafts with shrink-on wheel disks can be detected during the onset of crack growth by means of a newly developed test concept with slightly oblique longitudinal US wave incidence, and crack size estimates can be made. For process development and system adjustment a large reference specimen with circular and circular segment-type test reflectors was used. The results of comparative measurements with different types of devices and probes of different transducer size, test frequency and pulse length are presented, and the choice of the technical testing details is substantiated. (orig./DG) [de

  3. Scanning electron microscopy evaluation of the interaction pattern between dentin and resin after cavity preparation using Er:YAG laser

    International Nuclear Information System (INIS)

    Schein, Marcelo Thome

    2001-01-01

    The aim of this study was to describe the interaction pattern formed between dentin and resin on cavities prepared with an erbium laser (Er:YAG). The morphological aspect of the irradiated dentin after acid etching was also observed. Ten dentin disks were obtained from fresh extracted third molars. Each disk received two cavities, one prepared with a conventional high-speed drill, while the other cavity was obtained by the use of an Er:YAG laser (KaVo KEY Laser, KaVo Co.). The laser treatment was performed with 250 mJ/pulse, 4 Hz, non contact mode, focused beam, and a fine water mist was used. Five disks were prepared for morphological analysis of the acid etched dentin. The other five disks had their cavities restored with Single Bond (3M) followed by Z100 resin (3M). The specimens were observed under scanning electron microscopy after dentin-resin interface demineralization and deproteinization. It was observed that the morphological characteristics of the acid-etched irradiated dentin were not favorable to the diffusion of monomers through the collagen network. The dentin resin interfacial aspect of irradiated dentin, after acid etching, showed thin tags and scarce hybridization zones, which agreed with the morphology of the irradiated and acid-etched dentin substrate observed. (author)

  4. Single and Coupled Nanobeam Cavities

    DEFF Research Database (Denmark)

    Ivinskaya, Aliaksandra; Lavrinenko, Andrei; Shyroki, Dzmitry M.

    2013-01-01

    for analysis and design of photonic crystal devices, such as 2D ring resonators for filters, single and coupled nanobeam cavities, birefringence in photonic crystal cavities, threshold analysis in photonic crystal lasers, gap solitons in photonic crystals, novel photonic atolls, dynamic characteristics...

  5. Near-wall serpentine cooled turbine airfoil

    Science.gov (United States)

    Lee, Ching-Pang

    2013-09-17

    A serpentine coolant flow path (54A-54G) formed by inner walls (50, 52) in a cavity (49) between pressure and suction side walls (22, 24) of a turbine airfoil (20A). A coolant flow (58) enters (56) an end of the airfoil, flows into a span-wise channel (54A), then flows forward (54B) over the inner surface of the pressure side wall, then turns behind the leading edge (26), and flows back along a forward part of the suction side wall, then follows a loop (54E) forward and back around an inner wall (52), then flows along an intermediate part of the suction side wall, then flows into an aft channel (54G) between the pressure and suction side walls, then exits the trailing edge (28). This provides cooling matched to the heating topography of the airfoil, minimizes differential thermal expansion, revives the coolant, and minimizes the flow volume needed.

  6. Accretion Disks Around Binary Black Holes of Unequal Mass: GRMHD Simulations Near Decoupling

    Science.gov (United States)

    Gold, Roman; Paschalidis, Vasileios; Etienne, Zachariah B.; Shapiro, Stuart L.; Pfeiffer, Harald, P.

    2013-01-01

    We report on simulations in general relativity of magnetized disks onto black hole binaries. We vary the binary mass ratio from 1:1 to 1:10 and evolve the systems when they orbit near the binary disk decoupling radius. We compare (surface) density profiles, accretion rates (relative to a single, non-spinning black hole), variability, effective alpha-stress levels and luminosities as functions of the mass ratio. We treat the disks in two limiting regimes: rapid radiative cooling and no radiative cooling. The magnetic field lines clearly reveal jets emerging from both black hole horizons and merging into one common jet at large distances. The magnetic fields give rise to much stronger shock heating than the pure hydrodynamic flows, completely alter the disk structure, and boost accretion rates and luminosities. Accretion streams near the horizons are among the densest structures; in fact, the 1:10 no-cooling evolution results in a refilling of the cavity. The typical effective temperature in the bulk of the disk is approx. 10(exp5) (M / 10(exp 8)M solar mass (exp -1/4(L/L(sub edd) (exp 1/4K) yielding characteristic thermal frequencies approx. 10 (exp 15) (M /10(exp 8)M solar mass) (exp -1/4(L/L (sub edd) (1+z) (exp -1)Hz. These systems are thus promising targets for many extragalactic optical surveys, such as LSST, WFIRST, and PanSTARRS.

  7. Mechanical (turbines and auxiliary equipment)

    CERN Document Server

    Sherry, A; Cruddace, AE

    2013-01-01

    Modern Power Station Practice, Volume 3: Mechanical (Turbines and Auxiliary Equipment) focuses on the development of turbines and auxiliary equipment used in power stations in Great Britain. Topics covered include thermodynamics and steam turbine theory; turbine auxiliary systems such as lubrication systems, feed water heating systems, and the condenser and cooling water plants. Miscellaneous station services, and pipework in power plants are also described. This book is comprised of five chapters and begins with an overview of thermodynamics and steam turbine theory, paying particular attenti

  8. Dynamics of dense particle disks

    International Nuclear Information System (INIS)

    Araki, S.; Tremaine, S.; Toronto Univ., Canada)

    1986-01-01

    The present investigation of mechanical equilibrium and collisional transport processes in dense, differentially rotating particle disks is based on the Enskog (1922) theory of dense, hard sphere gases, with the single exception that the spheres are inelastic. The viscous instability suggested as a source of Saturn B ring structure does not arise in the models presented, although the ring may be subject to a phase transition analogous to the liquid-solid transition observed in molecular dynamics simulations of elastic hard spheres. In such a case, the ring would alternately exhibit zero-shear, or solid, and high shear, or liquid, zones. 29 references

  9. Technical tasks in superconducting cavities

    Energy Technology Data Exchange (ETDEWEB)

    Saito, Kenji [High Energy Accelerator Research Organization, Tsukuba, Ibaraki (Japan)

    1997-11-01

    The feature of superconducting rf cavities is an extremely small surface resistance on the wall. It brings a large energy saving in the operation, even those are cooled with liquid helium. That also makes possible to operate themselves in a higher field gradient comparing to normal conducting cavities, and brings to make accelerators compact. These merits are very important for the future accelerator engineering which is planed at JAERI for the neutron material science and nuclear waste transmutation. This machine is a high intensity proton linac and uses sc cavities in the medium and high {beta} sections. In this paper, starting R and D of proton superconducting cavities, several important technical points which come from the small surface resistance of sc cavities, are present to succeed it and also differences between the medium and high - {beta} structures are discussed. (author)

  10. Pacer processing: cavity inventory relationships

    International Nuclear Information System (INIS)

    Dietz, R.J.; Gritzo, L.A.

    1975-09-01

    The pacer cavity and its associated primary power loop comprise a recirculating system in which materials are introduced by a series of thermonuclear explosions while debris is continuously removed by radioactive decay, sorption phenomena, and deliberate processing. Safe, reliable, and economical realization of the Pacer concept depends on the removal and control of both noxious and valuable by-products of the fusion reaction. Mathematical relationships are developed that describe the quantities of materials that are introduced into the Pacer cavity by a series of discrete events and are removed continuously by processing and decay. An iterative computer program based on these relationships is developed that allows both the total cavity inventory and the amounts of important individual species to be determined at any time during the lifetime of the cavity in order to establish the effects of the thermonuclear event, the cavity, the flow, and various processing parameters on Pacer design requirements

  11. Astrophysical disks Collective and Stochastic Phenomena

    CERN Document Server

    Fridman, Alexei M; Kovalenko, Ilya G

    2006-01-01

    The book deals with collective and stochastic processes in astrophysical discs involving theory, observations, and the results of modelling. Among others, it examines the spiral-vortex structure in galactic and accretion disks , stochastic and ordered structures in the developed turbulence. It also describes sources of turbulence in the accretion disks, internal structure of disk in the vicinity of a black hole, numerical modelling of Be envelopes in binaries, gaseous disks in spiral galaxies with shock waves formation, observation of accretion disks in a binary system and mass distribution of luminous matter in disk galaxies. The editors adaptly brought together collective and stochastic phenomena in the modern field of astrophysical discs, their formation, structure, and evolution involving the methodology to deal with, the results of observation and modelling, thereby advancing the study in this important branch of astrophysics and benefiting Professional Researchers, Lecturers, and Graduate Students.

  12. Grain surface chemistry in protoplanetary disks

    International Nuclear Information System (INIS)

    Reboussin, Laura

    2015-01-01

    Planetary formation occurs in the protoplanetary disks of gas and dust. Although dust represents only 1% of the total disk mass, it plays a fundamental role in disk chemical evolution since it acts as a catalyst for the formation of molecules. Understanding this chemistry is therefore essential to determine the initial conditions from which planets form. During my thesis, I studied grain-surface chemistry and its impact on the chemical evolution of molecular cloud, initial condition for disk formation, and protoplanetary disk. Thanks to numerical simulations, using the gas-grain code Nautilus, I showed the importance of diffusion reactions and gas-grain interactions for the abundances of gas-phase species. Model results combined with observations also showed the effects of the physical structure (in temperature, density, AV) on the molecular distribution in disks. (author)

  13. Rotation of gas above the galactic disk

    International Nuclear Information System (INIS)

    Gvaramadze, V.V.; Lominadze, D.G.

    1988-01-01

    The galactic disk is modeled by an oblate spheroid with confocal spherodial isodensity surfaces. An explicit analytic expression is found for the angular velocity of the gas outside the disk. The parameters of a three-component model of a spiral galaxy (oblate spheroid with central hole, bulge, and massive corona) are chosen in such a way as to obtain in the disk a two-hump rotation curve (as in the Galaxy, M 31, and M 81). It is shown that at heights absolute value z ≤ 2 kpc the gas rotates in the same manner as the disk. However, at greater heights the rotation curve ceases to have two humps. Allowance for the pressure gradient of the gas slightly changes the rotation curve directly above the disk (r r/sub disk/)

  14. [Management of disk displacement with condylar fracture].

    Science.gov (United States)

    Yu, Shi-bin; Li, Zu-bing; Yang, Xue-wen; Zhao, Ji-hong; Dong, Yao-jun

    2003-07-01

    To investigate clinical features of disk displacement during the course of condylar fracture and to explore the techniques of disk reposition and suturation. 32 patients (10 females and 22 males) who had disk displacements with condylar fractures were followed up. Reduction and reposition of the dislocated disks simultaneously with fixation of fractures were performed. 7 patients underwent intermaxillary fixation with elastic bands for 1 to 2 weeks. The occlusions were satisfactory in all cases but one for the reason of ramus height loss. No TMJ symptom was found when examined 3 months post operation. Anterior disk displacements were most occurred with high condylar process fractures. Surgical reposition and suturation of disk play an important role for the later TMJ-function.

  15. Modeling turbine-missile impacts using the HONDO finite-element code

    International Nuclear Information System (INIS)

    Schuler, K.W.

    1981-11-01

    Calculations have been performed using the dynamic finite element code HONDO to simulate a full scale rocket sled test. In the test a rocket sled was used to launch at a velocity of 150 m/s (490 ft/s), a 1527 kg (3366 lb) fragment of a steam turbine rotor disk into a structure which was a simplified model of a steam turbine casing. In the calculations the material behavior of and boundary conditions on the target structure were varied to assess its energy absorbing characteristics. Comparisons are made between the calculations and observations of missile velocity and strain histories of various points of the target structure

  16. Circumstellar Gas in Young Planetary Debris Disks

    Science.gov (United States)

    Roberge, A.

    Circumstellar (CS) disks orbiting young stars fall into two categories: primordial disks, composed of unprocessed interstellar dust and gas, and debris disks, produced by the destruction of solid planetary bodies. In the first class, the most abundant gas is H_2; in the second, it appears that the H_2 gas has disappeared, possibly through incorporation into gas giant planets. The lifetime of H_2 gas in a CS disk is therefore of great importance, as it dictates the timescale for the formation of giant planets. FUSE observations of H_2 in CS disk systems have shown that FUV absorption spectroscopy may sensitively probe for small amounts of gas along the line of sight to the star. Most importantly, the FUSE non-detection of H_2 gas in the Beta Pictoris disk suggests that the primordial gas lifetime is less than about 12 Myr, and that gas giant planets must form very quickly. However, this suggestion is based on one system, and needs to be tested in additional systems with a range of ages, especially since there are indications that age is not the only factor in the evolution of a CS disk. We propose for FUSE observations of 3 additional debris disk systems, Fomalhaut, HD3003, and HD2884. Fomalhaut is an intermediate age debris disk, one of the Fabulous Four CS disks first discovered in 1984. The other two disks are younger, with ages similar to that of Beta Pic. All three stars are brighter in the FUV than Beta Pic, permitting us to sensitively probe for traces of H_2 gas. We will also measure the amount of secondary atomic gas produced from planetary bodies in these disks, in an effort to understand the entire evolution of CS gas in young planetary systems.

  17. MOLECULAR GAS IN YOUNG DEBRIS DISKS

    International Nuclear Information System (INIS)

    Moor, A.; Abraham, P.; Kiss, Cs.; Juhasz, A.; Kospal, A.; Pascucci, I.; Apai, D.; Henning, Th.; Csengeri, T.; Grady, C.

    2011-01-01

    Gas-rich primordial disks and tenuous gas-poor debris disks are usually considered as two distinct evolutionary phases of the circumstellar matter. Interestingly, the debris disk around the young main-sequence star 49 Ceti possesses a substantial amount of molecular gas and possibly represents the missing link between the two phases. Motivated to understand the evolution of the gas component in circumstellar disks via finding more 49 Ceti-like systems, we carried out a CO J = 3-2 survey with the Atacama Pathfinder EXperiment, targeting 20 infrared-luminous debris disks. These systems fill the gap between primordial and old tenuous debris disks in terms of fractional luminosity. Here we report on the discovery of a second 49 Ceti-like disk around the 30 Myr old A3-type star HD21997, a member of the Columba Association. This system was also detected in the CO(2-1) transition, and the reliable age determination makes it an even clearer example of an old gas-bearing disk than 49 Ceti. While the fractional luminosities of HD21997 and 49 Ceti are not particularly high, these objects seem to harbor the most extended disks within our sample. The double-peaked profiles of HD21997 were reproduced by a Keplerian disk model combined with the LIME radiative transfer code. Based on their similarities, 49 Ceti and HD21997 may be the first representatives of a so far undefined new class of relatively old (∼>8 Myr), gaseous dust disks. From our results, neither primordial origin nor steady secondary production from icy planetesimals can unequivocally explain the presence of CO gas in the disk of HD21997.

  18. Theory of Disk Accretion onto Magnetic Stars

    Directory of Open Access Journals (Sweden)

    Lai Dong

    2014-01-01

    Full Text Available Disk accretion onto magnetic stars occurs in a variety of systems, including accreting neutron stars (with both high and low magnetic fields, white dwarfs, and protostars. We review some of the key physical processes in magnetosphere-disk interaction, highlighting the theoretical uncertainties. We also discuss some applications to the observations of accreting neutron star and protostellar systems, as well as possible connections to protoplanetary disks and exoplanets.

  19. Disk access controller for Multi 8 computer

    International Nuclear Information System (INIS)

    Segalard, Jean

    1970-01-01

    After having presented the initial characteristics and weaknesses of the software provided for the control of a memory disk coupled with a Multi 8 computer, the author reports the development and improvement of this controller software. He presents the different constitutive parts of the computer and the operation of the disk coupling and of the direct access to memory. He reports the development of the disk access controller: software organisation, loader, subprograms and statements

  20. CONDOR simulation of an 11.4-GHz traveling wave output cavity

    International Nuclear Information System (INIS)

    Goren, Y.; Yu, D.

    1991-01-01

    The CONDOR code is used to simulate the cold test and the beam-induced microwave amplification of an 11.4-GHz, six-cell, disk-loaded, traveling wave cavity. Cold test simulation results are in agreement with a modified Slater's theory. Power extraction at the output port is calculated by launching a train of Gaussian electron bunches through the structure. Results are consistent with recent relativistic klystron experiments using a similar TW output cavity. It is further shown that, depending on operating beam parameters, the power extraction efficiency can be maximized by modification of various cells in the TW structure

  1. The Circumstellar Disk and Asymmetric Outflow of the EX Lup Outburst System

    Science.gov (United States)

    Hales, A. S.; Pérez, S.; Saito, M.; Pinte, C.; Knee, L. B. G.; de Gregorio-Monsalvo, I.; Dent, B.; López, C.; Plunkett, A.; Cortés, P.; Corder, S.; Cieza, L.

    2018-06-01

    We present Atacama Large Millimeter/submillimeter Array (ALMA) observations at 0.″3 resolution of EX Lup, the prototype of the EXor class of outbursting pre-main-sequence stars. The circumstellar disk of EX Lup is resolved for the first time in 1.3 mm continuum emission and in the J = 2–1 spectral line of three isotopologues of CO. At the spatial resolution and sensitivity achieved, the compact dust continuum disk shows no indications of clumps, fragments, or asymmetries above the 5σ level. Radiative transfer modeling constrains the characteristic radius of the dust disk to 23 au and the total dust mass to 1.0 × 10‑4 M ⊙ (33 M ⊕), similar to other EXor sources. The 13CO and C18O line emissions trace the disk rotation and are used to constrain the disk geometry, kinematics, and a total gas disk mass of 5.1 × 10‑4 M ⊙. The 12CO emission extends out to a radius of 200 au and is asymmetric, with one side deviating from Keplerian rotation. We detect blueshifted, 12CO arc-like emission located 0.″8 to the northwest and spatially disconnected from the disk emission. We interpret this extended structure as the brightened walls of a cavity excavated by an outflow, which are more commonly seen in FUor sources. Such outflows have also been seen in the borderline FU/EXor object V1647 Ori, but not toward EXor objects. Our detection provides evidence that the outflow phenomenon persists into the EXor phase, suggesting that FUor and EXor objects are a continuous population in which outflow activity declines with age, with transitional objects such as EX Lup and V1647 Ori.

  2. Great expectations: large wind turbines

    International Nuclear Information System (INIS)

    De Vries, E.

    2001-01-01

    This article focuses on wind turbine product development, and traces the background to wind turbines from the first generation 1.5 MW machines in 1995-6, plans for the second generation 3-5 MW class turbines to meet the expected boom in offshore wind projects, to the anticipated installation of a 4.5 MW turbine, and offshore wind projects planned for 2000-2002. The switch by the market leader Vestas to variable speed operation in 2000, the new product development and marketing strategy taken by the German Pro + Pro consultancy in their design of a 1.5 MW variable speed pitch control concept, the possible limiting of the size of turbines due to logistical difficulties, opportunities offered by air ships for large turbines, and the commissioning of offshore wind farms are discussed. Details of some 2-5 MW offshore wind turbine design specifications are tabulated

  3. IMAGING THE INNER AND OUTER GAPS OF THE PRE-TRANSITIONAL DISK OF HD 169142 AT 7 mm

    Energy Technology Data Exchange (ETDEWEB)

    Osorio, Mayra; Anglada, Guillem; Macías, Enrique; Gómez, José F.; Mayen-Gijon, Juan M. [Instituto de Astrofísica de Andalucía (CSIC), Glorieta de la Astronomía s/n, E-18008 Granada (Spain); Carrasco-González, Carlos; Rodríguez, Luis F.; D' Alessio, Paola [Centro de Radioastronomía y Astrofísica, UNAM, Apartado Postal 3-72 (Xangari), 58089 Morelia, Michoacán (Mexico); Torrelles, José M. [Institut de Ciències de l' Espai (CSIC)-Institut de Ciències del Cosmos (UB)/IEEC, Martí i Franquès 1, E-08028 Barcelona (Spain); Calvet, Nuria [Department of Astronomy, University of Michigan, 825 Dennison Building, 500 Church Street, Ann Arbor, MI 48109 (United States); Nagel, Erick [Departamento de Astronomía, Universidad de Guanajuato, Guanajuato, Gto 36240 (Mexico); Dent, William R. F. [ALMA SCO, Alonso de Córdova 3107, Vitacura, Santiago (Chile); Quanz, Sascha P.; Reggiani, Maddalena, E-mail: osorio@iaa.es [Institute for Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland)

    2014-08-20

    We present Very Large Array observations at 7 mm that trace the thermal emission of large dust grains in the HD 169142 protoplanetary disk. Our images show a ring of enhanced emission of radius ∼25-30 AU, whose inner region is devoid of detectable 7 mm emission. We interpret this ring as tracing the rim of an inner cavity or gap, possibly created by a planet or a substellar companion. The ring appears asymmetric, with the western part significantly brighter than the eastern one. This azimuthal asymmetry is reminiscent of the lopsided structures that are expected to be produced as a consequence of trapping of large dust grains. Our observations also reveal an outer annular gap at radii from ∼40 to ∼70 AU. Unlike other sources, the radii of the inner cavity, the ring, and the outer gap observed in the 7 mm images, which trace preferentially the distribution of large (millimeter/centimeter sized) dust grains, coincide with those obtained from a previous near-infrared polarimetric image, which traces scattered light from small (micron-sized) dust grains. We model the broadband spectral energy distribution and the 7 mm images to constrain the disk physical structure. From this modeling we infer the presence of a small (radius ∼0.6 AU) residual disk inside the central cavity, indicating that the HD 169142 disk is a pre-transitional disk. The distribution of dust in three annuli with gaps in between them suggests that the disk in HD 169142 is being disrupted by at least two planets or substellar objects.

  4. Wind Turbine Blade

    DEFF Research Database (Denmark)

    2010-01-01

    The invention relates to a blade for a wind turbine, particularly to a blade that may be produced by an advanced manufacturing process for producing a blade with high quality structural components. Particularly, the structural components, which are preferably manufactured from fibre reinforced...

  5. Alcoa wind turbines

    Science.gov (United States)

    Ai, D. K.

    1979-01-01

    An overview of Alcoa's wind energy program is given with emphasis on the the development of a low cost, reliable Darrieus Vertical Axis Wind Turbine System. The design layouts and drawings for fabrication are now complete, while fabrication and installation to utilize the design are expected to begin shortly.

  6. Turbine imaging technology assessment

    Energy Technology Data Exchange (ETDEWEB)

    Moursund, R. A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Carlson, T. J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2004-12-01

    The goal of this project was to identify and evaluate imaging technologies for observing juvenile fish within a Kaplan turbine, and specifically that would enable scientists to determine mechanisms of fish injury within an operating turbine unit. This report documents the opportunities and constraints for observing juvenile fish at specific locations during turbine passage. These observations were used to make modifications to dam structures and operations to improve conditions for fish passage while maintaining or improving hydropower production. The physical and hydraulic environment that fish experience as they pass through the hydroelectric plants were studied and the regions with the greatest potential for injury were defined. Biological response data were also studied to determine the probable types of injuries sustained in the turbine intake and what types of injuries are detectable with imaging technologies. The study grouped injury-causing mechanisms into two categories: fluid (pressure/cavitation, shear, turbulence) and mechanical (strike/collision, grinding/pinching, scraping). The physical constraints of the environment, together with the likely types of injuries to fish, provided the parameters needed for a rigorous imaging technology evaluation. Types of technology evaluated included both tracking and imaging systems using acoustic technologies (such as sonar and acoustic tags) and optic technologies (such as pulsed-laser videography, which is high-speed videography using a laser as the flash). Criteria for determining image data quality such as frame rate, target detectability, and resolution were used to quantify the minimum requirements of an imaging sensor.

  7. Small hydraulic turbine drives

    Science.gov (United States)

    Rostafinski, W. A.

    1970-01-01

    Turbine, driven by the fluid being pumped, requires no external controls, is completely integrated into the flow system, and has bearings which utilize the main fluid for lubrication and cooling. Torque capabilities compare favorably with those developed by positive displacement hydraulic motors.

  8. Gas turbine drives

    Energy Technology Data Exchange (ETDEWEB)

    1981-01-01

    Developments in gas turbine drives are reviewed, e.g., low weight per unit power and thrust-weight ratio, fast availability of the maximum speed, absolute resistance to cold and to droplet formation vibrationeless run, and low exhaust gas temperatures. Applications in aeronautic engineering (turbofan), power stations, marine propulsion systems, railways and road transportation vehicles are mentioned.

  9. Gas turbine electric generator

    International Nuclear Information System (INIS)

    Nemoto, Masaaki; Yuhara, Tetsuo.

    1993-01-01

    When troubles are caused to a boundary of a gas turbine electric generator, there is a danger that water as an operation medium for secondary circuits leaks to primary circuits, to stop a plant and the plant itself can not resume. Then in the present invention, helium gases are used as the operation medium not only for the primary circuits but also for the secondary circuits, to provide so-called a direct cycle gas turbine system. Further, the operation media of the primary and secondary circuits are recycled by a compressor driven by a primary circuit gas turbine, and the turbine/compressor is supported by helium gas bearings. Then, problems of leakage of oil and water from the bearings or the secondary circuits can be solved, further, the cooling device in the secondary circuit is constituted as a triple-walled tube structure by way of helium gas, to prevent direct leakage of coolants into the reactor core even if cracks are formed to pipes. (N.H.)

  10. Integrated turbine bypass system

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, L.H.; Dickenson, R.J.; Parry, W.T.; Retzlaff, K.M.

    1982-07-01

    Turbine steam-flow bypasses have been used for years in various sizes and applications. Because of differing system requirements, their use has been more predominant in Europe than in the United States. Recently, some utilities and consulting engineers have been re-evaluating their need for various types of bypass operation in fossil-fuelled power plants.

  11. Floating offshore turbines

    DEFF Research Database (Denmark)

    Tande, John Olav Giæver; Merz, Karl; Schmidt Paulsen, Uwe

    2014-01-01

    metric of energy production per unit steel mass. Floating offshore wind turbines represent a promising technology. The successful operation of HyWind and WindFloat in full scale demonstrates a well advanced technology readiness level, where further development will go into refining the concepts, cost...

  12. Radial gas turbine design

    Energy Technology Data Exchange (ETDEWEB)

    Krausche, S.; Ohlsson, Johan

    1998-04-01

    The objective of this work was to develop a program dealing with design point calculations of radial turbine machinery, including both compressor and turbine, with as few input data as possible. Some simple stress calculations and turbine metal blade temperatures were also included. This program was then implanted in a German thermodynamics program, Gasturb, a program calculating design and off-design performance of gas turbines. The calculations proceed with a lot of assumptions, necessary to finish the task, concerning pressure losses, velocity distribution, blockage, etc., and have been correlated with empirical data from VAT. Most of these values could have been input data, but to prevent the user of the program from drowning in input values, they are set as default values in the program code. The output data consist of geometry, Mach numbers, predicted component efficiency etc., and a number of graphical plots of geometry and velocity triangles. For the cases examined, the error in predicted efficiency level was within {+-} 1-2% points, and quite satisfactory errors in geometrical and thermodynamic conditions were obtained Examination paper. 18 refs, 36 figs

  13. Wind turbine state estimation

    DEFF Research Database (Denmark)

    Knudsen, Torben

    2014-01-01

    Dynamic inflow is an effect which is normally not included in the models used for wind turbine control design. Therefore, potential improvement from including this effect exists. The objective in this project is to improve the methods previously developed for this and especially to verify the res...

  14. How empty are disk gaps opened by giant planets?

    Energy Technology Data Exchange (ETDEWEB)

    Fung, Jeffrey [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, Ontario M5S 3H4 (Canada); Shi, Ji-Ming; Chiang, Eugene, E-mail: fung@astro.utoronto.ca [Department of Astronomy, UC Berkeley, Hearst Field Annex B-20, Berkeley, CA 94720-3411 (United States)

    2014-02-20

    Gap clearing by giant planets has been proposed to explain the optically thin cavities observed in many protoplanetary disks. How much material remains in the gap determines not only how detectable young planets are in their birth environments, but also how strong co-rotation torques are, which impacts how planets can survive fast orbital migration. We determine numerically how the average surface density inside the gap, Σ{sub gap}, depends on planet-to-star mass ratio q, Shakura-Sunyaev viscosity parameter α, and disk height-to-radius aspect ratio h/r. Our results are derived from our new graphics processing unit accelerated Lagrangian hydrodynamical code PEnGUIn and are verified by independent simulations with ZEUS90. For Jupiter-like planets, we find Σ{sub gap}∝q {sup –2.2}α{sup 1.4}(h/r){sup 6.6}, and for near brown dwarf masses, Σ{sub gap}∝q {sup –1}α{sup 1.3}(h/r){sup 6.1}. Surface density contrasts inside and outside gaps can be as large as 10{sup 4}, even when the planet does not accrete. We derive a simple analytic scaling, Σ{sub gap}∝q {sup –2}α{sup 1}(h/r){sup 5}, that compares reasonably well to empirical results, especially at low Neptune-like masses, and use discrepancies to highlight areas for progress.

  15. Thermal Comptonization in standard accretion disks

    International Nuclear Information System (INIS)

    Maraschi, L.; Molendi, S.

    1990-01-01

    Using the theory of geometrically thin accretion disks (where the effects of viscosity are parametrized in terms of the total pressure, viscosity parameter, α) equations are presented for the innermost region of the disk (where the pressure is due to radiation, and the main source of opacity is Thompson scattering). It is important to stress that the four equations can be solved without making use of an equation for the temperature. This is not true for the other regions of the disk. An equation given is used to determine the temperature, assuming that the disk is homogeneous and isothermal in the vertical direction. (author)

  16. Hard disks with SCSI interface

    CERN Document Server

    Denisov, O Yu

    1999-01-01

    The testing of 20 models of hard SCSI-disks is carried out: the Fujitsu MAE3091LP; the IBM DDRS-39130, DGHS-318220, DNES-318350, DRHS-36V and DRVS-18V; the Quantum Atlas VI 18.2; the Viking 11 9.1; the Seagate ST118202LW, ST118273LW, ST118273W, ST318203LW, ST318275LW, ST34520W, ST39140LW and ST39173W; and the Western Digital WDE9100-0007, WDE9100-AV0016, WDE9100-AV0030 and WDE9180-0048. All tests ran under the Windows NT 4.0 workstation operating system with Service Pack 4, under video mode with 1024*768 pixel resolution, 32- bit colour depth and V-frequency equal to 85 Hz. The detailed description and characteristics of SCSI stores are presented. Test results (ZD Winstone 99 and ZD WinBench 99 tests) are given in both table and diagram (disk transfer rate) forms. (0 refs).

  17. The Stability of Galaxy Disks

    Science.gov (United States)

    Westfall, K. B.; Andersen, D. R.; Bershady, M. A.; Martinsson, T. P. K.; Swaters, R. A.; Verheijen, M. A. W.

    2014-03-01

    We calculate the stellar surface mass density (Σ*) and two-component (gas+stars) disk stability (QRW) for 25 late-type galaxies from the DiskMass Survey. These calculations are based on fits of a dynamical model to our ionized-gas and stellar kinematic data performed using a Markov Chain Monte Carlo sampling of the Bayesian posterior. Marginalizing over all galaxies, we find a median value of QRW = 2.0±0.9 at 1.5 scale lengths. We also find that QRW is anti-correlated with the star-formation rate surface density (Σ*), which can be predicted using a closed set of empirical scaling relations. Finally, we find that the star-formation efficiency (Σ*/Σg) is correlated with Σ* and weakly anti-correlated with QRW. The former is consistent with an equilibrium prediction of Σ*/Σg ∝ Σ*1/2. Despite its order-of-magnitude range, we find no correlation of Σ*/ΣgΣ*1/2 with any other physical quantity derived by our study.

  18. Wind turbine having a direct-drive drivetrain

    Science.gov (United States)

    Bevington, Christopher M.; Bywaters, Garrett L.; Coleman, Clint C.; Costin, Daniel P.; Danforth, William L.; Lynch, Jonathan A.; Rolland, Robert H.

    2008-10-07

    A wind turbine (100) comprising an electrical generator (108) that includes a rotor assembly (112). A wind rotor (104) that includes a wind rotor hub (124) is directly coupled to the rotor assembly via a simplified connection. The wind rotor and generator rotor assembly are rotatably mounted on a central spindle (160) via a bearing assembly (180). The wind rotor hub includes an opening (244) having a diameter larger than the outside diameter of the central spindle adjacent the bearing assembly so as to allow access to the bearing assembly from a cavity (380) inside the wind rotor hub. The spindle is attached to a turret (140) supported by a tower (136). Each of the spindle, turret and tower has an interior cavity (172, 176, 368) that permits personnel to traverse therethrough to the cavity of the wind rotor hub. The wind turbine further includes a frictional braking system (276) for slowing, stopping or keeping stopped the rotation of the wind rotor and rotor assembly.

  19. Spiral Arms in the Asymmetrically Illuminated Disk of MWC 758 and Constraints on Giant Planets

    Science.gov (United States)

    Grady, C. A.; Muto, T.; Hashimoto, J.; Fukagawa, M.; Currie, T.; Biller, B.; Thalmann, C.; Sitko, M. L.; Russell, R.; Wisniewski, J.; hide

    2013-01-01

    We present the first near-IR scattered light detection of the transitional disk associated with the Herbig Ae star MWC 758 using data obtained as part of the Strategic Exploration of Exoplanets and Disks with Subaru, and 1.1 micrometer Hubble Space Telescope/NICMOS data. While submillimeter studies suggested there is a dust-depleted cavity with r = 0".35, we find scattered light as close as 0".1 (20-28 AU) from the star, with no visible cavity at H, K', or Ks . We find two small-scaled spiral structures that asymmetrically shadow the outer disk. We model one of the spirals using spiral density wave theory, and derive a disk aspect ratio of h approximately 0.18, indicating a dynamically warm disk. If the spiral pattern is excited by a perturber, we estimate its mass to be 5(exp +3)(sub -4) M(sub J), in the range where planet filtration models predict accretion continuing onto the star. Using a combination of non-redundant aperture masking data at L' and angular differential imaging with Locally Optimized Combination of Images at K' and Ks , we exclude stellar or massive brown dwarf companions within 300 mas of the Herbig Ae star, and all but planetary mass companions exterior to 0".5. We reach 5 sigma contrasts limiting companions to planetary masses, 3-4 M(sub J) at 1".0 and 2 M(sub J) at 1".55, using the COND models. Collectively, these data strengthen the case for MWC 758 already being a young planetary system.

  20. Frequency-feedback cavity enhanced spectrometer

    Science.gov (United States)

    Hovde, David Christian; Gomez, Anthony

    2015-08-18

    A spectrometer comprising an optical cavity, a light source capable of producing light at one or more wavelengths transmitted by the cavity and with the light directed at the cavity, a detector and optics positioned to collect light transmitted by the cavity, feedback electronics causing oscillation of amplitude of the optical signal on the detector at a frequency that depends on cavity losses, and a sensor measuring the oscillation frequency to determine the cavity losses.

  1. Nonlocal Intracranial Cavity Extraction

    Science.gov (United States)

    Manjón, José V.; Eskildsen, Simon F.; Coupé, Pierrick; Romero, José E.; Collins, D. Louis; Robles, Montserrat

    2014-01-01

    Automatic and accurate methods to estimate normalized regional brain volumes from MRI data are valuable tools which may help to obtain an objective diagnosis and followup of many neurological diseases. To estimate such regional brain volumes, the intracranial cavity volume (ICV) is often used for normalization. However, the high variability of brain shape and size due to normal intersubject variability, normal changes occurring over the lifespan, and abnormal changes due to disease makes the ICV estimation problem challenging. In this paper, we present a new approach to perform ICV extraction based on the use of a library of prelabeled brain images to capture the large variability of brain shapes. To this end, an improved nonlocal label fusion scheme based on BEaST technique is proposed to increase the accuracy of the ICV estimation. The proposed method is compared with recent state-of-the-art methods and the results demonstrate an improved performance both in terms of accuracy and reproducibility while maintaining a reduced computational burden. PMID:25328511

  2. Nonlocal Intracranial Cavity Extraction

    Directory of Open Access Journals (Sweden)

    José V. Manjón

    2014-01-01

    Full Text Available Automatic and accurate methods to estimate normalized regional brain volumes from MRI data are valuable tools which may help to obtain an objective diagnosis and followup of many neurological diseases. To estimate such regional brain volumes, the intracranial cavity volume (ICV is often used for normalization. However, the high variability of brain shape and size due to normal intersubject variability, normal changes occurring over the lifespan, and abnormal changes due to disease makes the ICV estimation problem challenging. In this paper, we present a new approach to perform ICV extraction based on the use of a library of prelabeled brain images to capture the large variability of brain shapes. To this end, an improved nonlocal label fusion scheme based on BEaST technique is proposed to increase the accuracy of the ICV estimation. The proposed method is compared with recent state-of-the-art methods and the results demonstrate an improved performance both in terms of accuracy and reproducibility while maintaining a reduced computational burden.

  3. Analysis of Dust and Fission Products in PBMR Turbine

    International Nuclear Information System (INIS)

    Stempniewicz, M.M.; Wessels, D.

    2014-01-01

    A 400 MWth direct cycle Pebble Bed Modular reactor was under development in South Africa. The work performed included design and safety analyses. In HTR/PBMR, graphite dust is generated during normal reactor operation due to pebble-to-pebble scratching. This dust will be deposited throughout the primary system. Furthermore, the dust will become radioactive due to sorption of fission products released, although in very small quantities, during normal operation. This paper presents a model and analyses of the PBMR turbine with the SPECTRA code. The purpose of the present work was to estimate the amount and distribution of deposited dust and the fission products, namely cesium, iodine, and silver, during plant life-time, which was assumed to be 40 full-power years. The performed work showed that after 40 years of plant life-time deposited layers are very small. The largest deposition is of course observed on the dust filters. Apart from the dust filters, the largest dust deposition is observed on the: • Outer Casing (inner walls) • Turbine Rotor Cooling Cavity (inner walls) • HPC Cold Cooling Gas Header (inner walls) This is caused by relatively low gas velocities in these volumes. The low velocities allow a continuous build-up of the dust layer. About 90% of cesium, 40% of iodine, and 99.9% of silver is adsorbed on the metallic structures of the turbine. The sorption rate increases along the turbine due to decreasing temperatures. In case of cesium and iodine the highest concentrations are observed in the last stage (stage 12) of the turbine. In the case of silver the sorption is so large that the silver vapor is significantly depleted in the last stages of the turbine. This is a reason for having a maximum in silver concentration in the stage 10. In the following stages the concentration decreases due to very small silver vapor fraction in the gas. (author)

  4. ON THE TRANSITIONAL DISK CLASS: LINKING OBSERVATIONS OF T TAURI STARS AND PHYSICAL DISK MODELS

    International Nuclear Information System (INIS)

    Espaillat, C.; Andrews, S.; Qi, C.; Wilner, D.; Ingleby, L.; Calvet, N.; Hernández, J.; Furlan, E.; D'Alessio, P.; Muzerolle, J.

    2012-01-01

    Two decades ago 'transitional disks' (TDs) described spectral energy distributions (SEDs) of T Tauri stars with small near-IR excesses, but significant mid- and far-IR excesses. Many inferred this indicated dust-free holes in disks possibly cleared by planets. Recently, this term has been applied disparately to objects whose Spitzer SEDs diverge from the expectations for a typical full disk (FD). Here, we use irradiated accretion disk models to fit the SEDs of 15 such disks in NGC 2068 and IC 348. One group has a 'dip' in infrared emission while the others' continuum emission decreases steadily at all wavelengths. We find that the former have an inner disk hole or gap at intermediate radii in the disk and we call these objects 'transitional disks' and 'pre-transitional disks' (PTDs), respectively. For the latter group, we can fit these SEDs with FD models and find that millimeter data are necessary to break the degeneracy between dust settling and disk mass. We suggest that the term 'transitional' only be applied to objects that display evidence for a radical change in the disk's radial structure. Using this definition, we find that TDs and PTDs tend to have lower mass accretion rates than FDs and that TDs have lower accretion rates than PTDs. These reduced accretion rates onto the star could be linked to forming planets. Future observations of TDs and PTDs will allow us to better quantify the signatures of planet formation in young disks.

  5. DUST FILTRATION BY PLANET-INDUCED GAP EDGES: IMPLICATIONS FOR TRANSITIONAL DISKS

    International Nuclear Information System (INIS)

    Zhu Zhaohuan; Dong Ruobing; Nelson, Richard P.; Espaillat, Catherine; Hartmann, Lee

    2012-01-01

    By carrying out two-dimensional two-fluid global simulations, we have studied the response of dust to gap formation by a single planet in the gaseous component of a protoplanetary disk—the so-called dust filtration mechanism. We have found that a gap opened by a giant planet at 20 AU in an α = 0.01, M-dot =10 -8 M ☉ yr -1 disk can effectively stop dust particles larger than 0.1 mm drifting inward, leaving a submillimeter (submm) dust cavity/hole. However, smaller particles are difficult to filter by a gap induced by a several M J planet due to (1) dust diffusion and (2) a high gas accretion velocity at the gap edge. Based on these simulations, an analytic model is derived to understand what size particles can be filtered by the planet-induced gap edge. We show that a dimensionless parameter T s /α, which is the ratio between the dimensionless dust stopping time and the disk viscosity parameter, is important for the dust filtration process. Finally, with our updated understanding of dust filtration, we have computed Monte Carlo radiative transfer models with variable dust size distributions to generate the spectral energy distributions of disks with gaps. By comparing with transitional disk observations (e.g., GM Aur), we have found that dust filtration alone has difficulties depleting small particles sufficiently to explain the near-IR deficit of moderate M-dot transitional disks, except under some extreme circumstances. The scenario of gap opening by multiple planets studied previously suffers the same difficulty. One possible solution is to invoke both dust filtration and dust growth in the inner disk. In this scenario, a planet-induced gap filters large dust particles in the disk, and the remaining small dust particles passing to the inner disk can grow efficiently without replenishment from fragmentation of large grains. Predictions for ALMA have also been made based on all these scenarios. We conclude that dust filtration with planet(s) in the disk is a

  6. Photons in a spherical cavity

    International Nuclear Information System (INIS)

    Ionescu-Pallas, N.; Vlad, V.I.

    1999-01-01

    The spectrum of black body radiation at the absolute temperature T, in an ideal spherical cavity of radius R, is studied. The departures from the classical predictions of Planck's theory, due to the discrete energies of the radiation quanta confined inside the cavity, depend on the adiabatic invariant RT and are significant for RT≤ 1 cm K. Special attention was paid to evidence sudden changes in the spectrum intensities, forbidden bands of frequency, as well as major modifications of the total energy for RT≤ 1 cm K. Similar effects were present in case of a cubic cavity too. (authors)

  7. Water turbine technology for small power stations

    Science.gov (United States)

    Salovaara, T.

    1980-02-01

    The paper examines hydro-power stations and the efficiency and costs of using water turbines to run them. Attention is given to different turbine types emphasizing the use of Kaplan-turbines and runners. Hydraulic characteristics and mechanical properties of low head turbines and small turbines, constructed of fully fabricated steel plate structures, are presented.

  8. SMART POWER TURBINE

    Energy Technology Data Exchange (ETDEWEB)

    Nirm V. Nirmalan

    2003-11-01

    Gas turbines are the choice technology for high-performance power generation and are employed in both simple and combined cycle configurations around the world. The Smart Power Turbine (SPT) program has developed new technologies that are needed to further extend the performance and economic attractiveness of gas turbines for power generation. Today's power generation gas turbines control firing temperatures indirectly, by measuring the exhaust gas temperature and then mathematically calculating the peak combustor temperatures. But temperatures in the turbine hot gas path vary a great deal, making it difficult to control firing temperatures precisely enough to achieve optimal performance. Similarly, there is no current way to assess deterioration of turbine hot-gas-path components without shutting down the turbine. Consequently, maintenance and component replacements are often scheduled according to conservative design practices based on historical fleet-averaged data. Since fuel heating values vary with the prevalent natural gas fuel, the inability to measure heating value directly, with sufficient accuracy and timeliness, can lead to maintenance and operational decisions that are less than optimal. GE Global Research Center, under this Smart Power Turbine program, has developed a suite of novel sensors that would measure combustor flame temperature, online fuel lower heating value (LHV), and hot-gas-path component life directly. The feasibility of using the ratio of the integrated intensities of portions of the OH emission band to determine the specific average temperature of a premixed methane or natural-gas-fueled combustion flame was demonstrated. The temperature determined is the temperature of the plasma included in the field of view of the sensor. Two sensor types were investigated: the first used a low-resolution fiber optic spectrometer; the second was a SiC dual photodiode chip. Both methods worked. Sensitivity to flame temperature changes was

  9. Turbine repair process, repaired coating, and repaired turbine component

    Science.gov (United States)

    Das, Rupak; Delvaux, John McConnell; Garcia-Crespo, Andres Jose

    2015-11-03

    A turbine repair process, a repaired coating, and a repaired turbine component are disclosed. The turbine repair process includes providing a turbine component having a higher-pressure region and a lower-pressure region, introducing particles into the higher-pressure region, and at least partially repairing an opening between the higher-pressure region and the lower-pressure region with at least one of the particles to form a repaired turbine component. The repaired coating includes a silicon material, a ceramic matrix composite material, and a repaired region having the silicon material deposited on and surrounded by the ceramic matrix composite material. The repaired turbine component a ceramic matrix composite layer and a repaired region having silicon material deposited on and surrounded by the ceramic matrix composite material.

  10. Performance of a single nutating disk engine in the 2 to 500 kW power range

    International Nuclear Information System (INIS)

    Korakianitis, T.; Boruta, M.; Jerovsek, J.; Meitner, P.L.

    2009-01-01

    A new type of internal combustion engine with distinct advantages over conventional piston-engines and gas turbines in small power ranges is presented. The engine has analogies with piston engine operation, but like gas turbines it has dedicated spaces and devices for compression, burning and expansion. The engine operates on a modified limited-pressure thermodynamic cycle. The core of the engine is a nutating non-rotating disk, with the center of its hub mounted in the middle of a Z-shaped shaft. The two ends of the shaft rotate, while the disk nutates. The motion of the disk circumference prescribes a portion of a sphere. In the single-disk configuration a portion of the surface area of the disk is used for intake and compression, a portion is used to seal against a center casing, and the remaining portion is used for expansion and exhaust. The compressed air is admitted to an external accumulator, and then into an external combustion chamber before it is admitted to the power side of the disk. The external combustion chamber enables the engine to operate on a variable compression ratio cycle. Variations in cycle temperature ratio and compression ratio during normal operation enable the engine to effectively become a variable-cycle engine, allowing significant flexibility for optimizing efficiency or power output. The thermal efficiency is similar to that of medium sized diesel engines. For the same engine volume and weight this engine produces approximately twice the power of a two-stroke engine and four times the power of a four-stroke engine. The computed sea-level engine performance at design and off-design conditions in the 2 to 500 kW power range is presented.

  11. Discussion of mechanical design for pressured cavity-air-receiver in solar power tower system

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Zhilin; Zhang, Yaoming; Liu, Deyou; Wang, Jun; Liu, Wei [Hohai Univ., Nanjing (China). New Materials and Energy Sources Research and Exploitation Inst.

    2008-07-01

    In 2005, Hohai university and Nanjing Chunhui science and technology Ltd. of China, cooperating with Weizmann Institute of Science and EDIG Ltd. of Israel, built up a 70kWe solar power tower test plant in Nanjing, Jiangsu province, China, which was regarded as the first demonstration project to demonstrate the feasibility of solar power tower system in China. The system consists of heliostats field providing concentrated sunlight, a solar tower with a height of 33 meter, a pressured cavity-air-receiver transforming solar energy to thermal energy, a modified gas turbine adapting to solar power system, natural gas subsystem for solar-hybrid generation, cooling water subsystem for receiver and CPC, controlling subsystem for whole plant, et al. In this system, air acts as actuating medium and the system works in Brayton cycle. Testing results show that solar power tower system is feasible in China. To promote the development of solar powered gas turbine system and the pressured cavity-air-receiver technology in China, it is necessary to study the mechanical design for pressured Cavity-air-receiver. Mechanical design of pressured cavity-air-receiver is underway and some tentative principles for pressured cavity-air-receiver design, involving in power matching, thermal efficiency, material choosing, and equipment security and machining ability, are presented. At the same time, simplified method and process adapted to engineering application for the mechanical design of pressured cavity-air-receiver are discussed too. Furthermore, some design parameters and appearance of a test sample of pressured cavity-air-receiver designed in this way is shown. It is appealed that, in China, the research in this field should be intensified and independent knowledge patents for pivotal technological equipments such as receiver in solar power tower system should be formed. (orig.)

  12. A UV-to-NIR Study of Molecular Gas in the Dust Cavity around RY Lupi

    Science.gov (United States)

    Arulanantham, N.; France, K.; Hoadley, K.; Manara, C. F.; Schneider, P. C.; Alcalá, J. M.; Banzatti, A.; Günther, H. M.; Miotello, A.; van der Marel, N.; van Dishoeck, E. F.; Walsh, C.; Williams, J. P.

    2018-03-01

    We present a study of molecular gas in the inner disk (rgas in a surface layer between r = 0.1–10 au, as traced by Lyα-pumped H2. The result shows H2 emission originating in a ring centered at ∼3 au that declines within r gas emitting from radially separated disk regions ( ∼ 0.4+/- 0.1 {au}; ∼ 3+/- 2 {au}). The 4.7 μm 12CO emission lines are also well fit by two-component profiles ( =0.4+/- 0.1 {au}; =15+/- 2 {au}). We combine these results with 10 μm observations to form a picture of gapped structure within the mm-imaged dust cavity, providing the first such overview of the inner regions of a young disk. The HST SED of RY Lupi is available online for use in modeling efforts.

  13. Simulations of Steady Cavitating Flow in a Small Francis Turbine

    Directory of Open Access Journals (Sweden)

    Ahmed Laouari

    2016-01-01

    Full Text Available The turbulent flow through a small horizontal Francis turbine is solved by means of Ansys-CFX at different operating points, with the determination of the hydrodynamic performance and the best efficiency point. The flow structures at different regimes reveal a large flow eddy in the runner and a swirl in the draft tube. The use of the mixture model for the cavity/liquid two-phase flow allowed studying the influence of cavitation on the hydrodynamic performance and revealed cavitation pockets near the trailing edge of the runner and a cavitation vortex rope in the draft tube. By maintaining a constant dimensionless head and a distributor vane opening while gradually increasing the cavitation number, the output power and efficiency reached a critical point and then had begun to stabilize. The cavitation number corresponding to the safety margin of cavitation is also predicted for this hydraulic turbine.

  14. Scaling Ratios and Triangles in Siegel Disks

    DEFF Research Database (Denmark)

    Buff, Xavier; Henriksen, Christian

    1999-01-01

    Let f(z)=e^{2i\\pi \\theta} + z^2, where \\theta is a quadratic irrational. McMullen proved that the Siegel disk for f is self-similar about the critical point, and we show that if \\theta = (\\sqrt{5}-1)/2 is the golden mean, then there exists a triangle contained in the Siegel disk, and with one...

  15. Attention Novices: Friendly Intro to Shiny Disks.

    Science.gov (United States)

    Bardes, D'Ellen

    1986-01-01

    Provides an overview of how optical storage technologies--videodisk, Write-Once disks, and CD-ROM CD-I disks are built into and controlled via DEC, Apple, Atari, Amiga, and IBM PC compatible microcomputers. Several available products are noted and a list of producers is included. (EM)

  16. Circumstellar disks around binary stars in Taurus

    International Nuclear Information System (INIS)

    Akeson, R. L.; Jensen, E. L. N.

    2014-01-01

    We have conducted a survey of 17 wide (>100 AU) young binary systems in Taurus with the Atacama Large Millimeter Array (ALMA) at two wavelengths. The observations were designed to measure the masses of circumstellar disks in these systems as an aid to understanding the role of multiplicity in star and planet formation. The ALMA observations had sufficient resolution to localize emission within the binary system. Disk emission was detected around all primaries and 10 secondaries, with disk masses as low as 10 –4 M ☉ . We compare the properties of our sample to the population of known disks in Taurus and find that the disks from this binary sample match the scaling between stellar mass and millimeter flux of F mm ∝M ∗ 1.5--2.0 to within the scatter found in previous studies. We also compare the properties of the primaries to those of the secondaries and find that the secondary/primary stellar and disk mass ratios are not correlated; in three systems, the circumsecondary disk is more massive than the circumprimary disk, counter to some theoretical predictions.

  17. Circumstellar disks around binary stars in Taurus

    Energy Technology Data Exchange (ETDEWEB)

    Akeson, R. L. [NASA Exoplanet Science Institute, IPAC/Caltech, Pasadena, CA 91125 (United States); Jensen, E. L. N. [Swarthmore College, Department of Physics and Astronomy, Swarthmore, PA 19081 (United States)

    2014-03-20

    We have conducted a survey of 17 wide (>100 AU) young binary systems in Taurus with the Atacama Large Millimeter Array (ALMA) at two wavelengths. The observations were designed to measure the masses of circumstellar disks in these systems as an aid to understanding the role of multiplicity in star and planet formation. The ALMA observations had sufficient resolution to localize emission within the binary system. Disk emission was detected around all primaries and 10 secondaries, with disk masses as low as 10{sup –4} M {sub ☉}. We compare the properties of our sample to the population of known disks in Taurus and find that the disks from this binary sample match the scaling between stellar mass and millimeter flux of F{sub mm}∝M{sub ∗}{sup 1.5--2.0} to within the scatter found in previous studies. We also compare the properties of the primaries to those of the secondaries and find that the secondary/primary stellar and disk mass ratios are not correlated; in three systems, the circumsecondary disk is more massive than the circumprimary disk, counter to some theoretical predictions.

  18. Improper colouring of (random) unit disk graphs

    NARCIS (Netherlands)

    Kang, R.J.; Müller, T.; Sereni, J.S.

    2008-01-01

    For any graph G, the k-improper chromatic number ¿k(G) is the smallest number of colours used in a colouring of G such that each colour class induces a subgraph of maximum degree k. We investigate ¿k for unit disk graphs and random unit disk graphs to generalise results of McDiarmid and Reed

  19. A PRIMER ON UNIFYING DEBRIS DISK MORPHOLOGIES

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eve J.; Chiang, Eugene, E-mail: evelee@berkeley.edu, E-mail: echiang@astro.berkeley.edu [Department of Astronomy, University of California Berkeley, Berkeley, CA 94720-3411 (United States)

    2016-08-20

    A “minimum model” for debris disks consists of a narrow ring of parent bodies, secularly forced by a single planet on a possibly eccentric orbit, colliding to produce dust grains that are perturbed by stellar radiation pressure. We demonstrate how this minimum model can reproduce a wide variety of disk morphologies imaged in scattered starlight. Five broad categories of disk shape can be captured: “rings,” “needles,” “ships-and-wakes,” “bars,” and “moths (a.k.a. fans),” depending on the viewing geometry. Moths can also sport “double wings.” We explain the origin of morphological features from first principles, exploring the dependence on planet eccentricity, disk inclination dispersion, and the parent body orbital phases at which dust grains are born. A key determinant in disk appearance is the degree to which dust grain orbits are apsidally aligned. Our study of a simple steady-state (secularly relaxed) disk should serve as a reference for more detailed models tailored to individual systems. We use the intuition gained from our guidebook of disk morphologies to interpret, informally, the images of a number of real-world debris disks. These interpretations suggest that the farthest reaches of planetary systems are perturbed by eccentric planets, possibly just a few Earth masses each.

  20. A PRIMER ON UNIFYING DEBRIS DISK MORPHOLOGIES

    International Nuclear Information System (INIS)

    Lee, Eve J.; Chiang, Eugene

    2016-01-01

    A “minimum model” for debris disks consists of a narrow ring of parent bodies, secularly forced by a single planet on a possibly eccentric orbit, colliding to produce dust grains that are perturbed by stellar radiation pressure. We demonstrate how this minimum model can reproduce a wide variety of disk morphologies imaged in scattered starlight. Five broad categories of disk shape can be captured: “rings,” “needles,” “ships-and-wakes,” “bars,” and “moths (a.k.a. fans),” depending on the viewing geometry. Moths can also sport “double wings.” We explain the origin of morphological features from first principles, exploring the dependence on planet eccentricity, disk inclination dispersion, and the parent body orbital phases at which dust grains are born. A key determinant in disk appearance is the degree to which dust grain orbits are apsidally aligned. Our study of a simple steady-state (secularly relaxed) disk should serve as a reference for more detailed models tailored to individual systems. We use the intuition gained from our guidebook of disk morphologies to interpret, informally, the images of a number of real-world debris disks. These interpretations suggest that the farthest reaches of planetary systems are perturbed by eccentric planets, possibly just a few Earth masses each.

  1. A Primer on Unifying Debris Disk Morphologies

    Science.gov (United States)

    Lee, Eve J.; Chiang, Eugene

    2016-08-01

    A “minimum model” for debris disks consists of a narrow ring of parent bodies, secularly forced by a single planet on a possibly eccentric orbit, colliding to produce dust grains that are perturbed by stellar radiation pressure. We demonstrate how this minimum model can reproduce a wide variety of disk morphologies imaged in scattered starlight. Five broad categories of disk shape can be captured: “rings,” “needles,” “ships-and-wakes,” “bars,” and “moths (a.k.a. fans),” depending on the viewing geometry. Moths can also sport “double wings.” We explain the origin of morphological features from first principles, exploring the dependence on planet eccentricity, disk inclination dispersion, and the parent body orbital phases at which dust grains are born. A key determinant in disk appearance is the degree to which dust grain orbits are apsidally aligned. Our study of a simple steady-state (secularly relaxed) disk should serve as a reference for more detailed models tailored to individual systems. We use the intuition gained from our guidebook of disk morphologies to interpret, informally, the images of a number of real-world debris disks. These interpretations suggest that the farthest reaches of planetary systems are perturbed by eccentric planets, possibly just a few Earth masses each.

  2. Grinding Glass Disks On A Belt Sander

    Science.gov (United States)

    Lyons, James J., III

    1995-01-01

    Small machine attached to table-top belt sander makes possible to use belt sander to grind glass disk quickly to specified diameter within tolerance of about plus or minus 0.002 in. Intended to be used in place of production-shop glass grinder. Held on driveshaft by vacuum, glass disk rotated while periphery ground by continuous sanding belt.

  3. Recent development of disk lasers at TRUMPF

    Science.gov (United States)

    Schad, Sven-Silvius; Gottwald, Tina; Kuhn, Vincent; Ackermann, Matthias; Bauer, Dominik; Scharun, Michael; Killi, Alexander

    2016-03-01

    The disk laser is one of the most important laser concepts for today's industrial laser market. Offering high brilliance at low cost, high optical efficiency and great application flexibility the disk laser paved the way for many industrial laser applications. Over the past years power and brightness increased and the disk laser turned out to be a very versatile laser source, not only for welding but also for cutting. Both, the quality and speed of cutting are superior to CO2-based lasers for a vast majority of metals, and, most important, in a broad thickness range. In addition, due to the insensitivity against back reflections the disk laser is well suited for cutting highly reflective metal such as brass or copper. These advantages facilitate versatile cutting machines and explain the high and growing demand for disk lasers for applications besides welding applications that can be observed today. From a today's perspective the disk principle has not reached any fundamental limits regarding output power per disk or beam quality, and offers numerous advantages over other high power resonator concepts, especially over fiber lasers or direct diode lasers. This paper will give insight in the latest progress in kilowatt class cw disk laser technology at TRUMPF and will discuss recent power scaling results as well.

  4. Disk Galaxies : Building Blocks of the Universe?

    OpenAIRE

    Bower, Richard

    2016-01-01

    In my talk I look at the origin of disk galaxies from the theoretical perspective. In particular I look at simple ways to use the properties of disk galaxies, and their evolution, to test our current paradigm for galaxy formation within the CDM scenario.

  5. Protoplanetary disks and exoplanets in scattered light

    NARCIS (Netherlands)

    Stolker, T.

    2017-01-01

    High-contrast imaging facilitates the direct detection of protoplanetary disks in scattered light and self-luminous exoplanets on long-period orbits. The combined power of extreme adaptive optics and differential imaging techniques delivers high spatial resolution images of disk morphologies down to

  6. 10 MB disk platter from CDC 7638

    CERN Multimedia

    1974-01-01

    This magnetic disk was one of three which interfaced with various Control Data machines. This single platter came from a Control Data 7638 Disk Storage Subsystem and could contain up to 10MB - about the size of a few MP4's on your iPod.

  7. Cavity and goaf control

    Energy Technology Data Exchange (ETDEWEB)

    Stassen, P

    1978-01-01

    A summary of stowing, including a definition, calculation of stowing material requirements and settling of packs is given. A) Stowing using dirt found locally - the dirt bands in the seam - the use of ripping dirt brought down by the scraper loader and used for packing purposes and the construction of dummy roads. B) Control of cavities by leaving short, thick props and timber chocks in place. C) Stowing methods involving imported firt: packing by hand, use of scraper loaders, slinger stowing and control led-gravity stowing. D) Pneumatic stowing: describes the various types of machine and their scope; pipelines, their installation and cost price; pneumatic stowing in conjunc tion with powered supports; the use of crusher-stowers for stowing ripping dirt; construction of anhydrite packs by means of a pneumatic stower. E) Hydraulic stowing: how it works, the materials involved, utilization conditions, the surface storage post, pipes, stoppings with stowed material, water removal, rates of hydraulic stowing, results of theoretical studies, and the use of hydraulic stowing in the metal-mines. F) Pumped packs: how they work, how the packs are installed, the strength of the packs and their various uses. G) Caving: describes the principle of caving, support patterns, caving with packs and makes a comparison between caving and stowing. H) Comparison between the various methods of stowing compares pneumatic with hydraulic stowing methods; compares packing by hand and mechanical stowing compares surface subsidence in terms of the method of goaf used underground. An appendix gives details of equipment used. (15 refs.) (In French)

  8. Loggerhead oral cavity morphometry study

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Standard external morphometrics and internal oral cavity morphometrics data were collected on wild and captive reared loggerhead sea turtles in size classes ranging...

  9. Niobium LEP 2 accelerating cavities

    CERN Multimedia

    An accelerating cavity from LEP. This could be cut open to show the layer of niobium on the inside. Operating at 4.2 degrees above absolute zero, the niobium is superconducting and carries an accelerating field of 6 million volts per metre with negligible losses. Each cavity has a surface of 6 m2. The niobium layer is only 1.2 microns thick, ten times thinner than a hair. Such a large area had never been coated to such a high accuracy. A speck of dust could ruin the performance of the whole cavity so the work had to be done in an extremely clean environment. These challenging requirements pushed European industry to new achievements. 256 of these cavities were used in an upgrade of the LEP accelerator to double the energy of the particle beams.

  10. Bistability of Cavity Magnon Polaritons

    Science.gov (United States)

    Wang, Yi-Pu; Zhang, Guo-Qiang; Zhang, Dengke; Li, Tie-Fu; Hu, C.-M.; You, J. Q.

    2018-01-01

    We report the first observation of the magnon-polariton bistability in a cavity magnonics system consisting of cavity photons strongly interacting with the magnons in a small yttrium iron garnet (YIG) sphere. The bistable behaviors emerged as sharp frequency switchings of the cavity magnon polaritons (CMPs) and related to the transition between states with large and small numbers of polaritons. In our experiment, we align, respectively, the [100] and [110] crystallographic axes of the YIG sphere parallel to the static magnetic field and find very different bistable behaviors (e.g., clockwise and counter-clockwise hysteresis loops) in these two cases. The experimental results are well fitted and explained as being due to the Kerr nonlinearity with either a positive or negative coefficient. Moreover, when the magnetic field is tuned away from the anticrossing point of CMPs, we observe simultaneous bistability of both magnons and cavity photons by applying a drive field on the lower branch.

  11. Design of rf conditioner cavities

    International Nuclear Information System (INIS)

    Govil, R.; Rimmer, R.A.; Sessler, A.; Kirk, H.G.

    1992-06-01

    Theoretical studies are made of radio frequency structures which can be used to condition electron beams so as to greatly reduce the stringent emittance requirements for successful lasing in a free-electron laser. The basic strategy of conditioning calls for modulating an electron beam in the transverse dimension, by a periodic focusing channel, while it traverses a series of rf cavities, each operating in a TM 210 mode. In this paper, we analyze the cavities both analytically and numerically (using MAFIA simulations). We find that when cylindrical symmetry is broken the coupling impedance can be greatly enhanced. We present results showing various performance characteristics as a function of cavity parameters, as well as possible designs for conditioning cavities

  12. SRF Cavity Fabrication and Materials

    CERN Document Server

    Singer, W

    2014-07-17

    The technological and metallurgical requirements of material for highgradient superconducting cavities are described. High-purity niobium, as the preferred metal for the fabrication of superconducting accelerating cavities, should meet exact specifications. The content of interstitial impurities such as oxygen, nitrogen, and carbon must be below 10μg/g. The hydrogen content should be kept below 2μg/g to prevent degradation of the Q-value under certain cool-down conditions. The material should be free of flaws (foreign material inclusions or cracks and laminations) that can initiate a thermal breakdown. Defects may be detected by quality control methods such as eddy current scanning and identified by a number of special methods. Conventional and alternative cavity fabrication methods are reviewed. Conventionally, niobium cavities are fabricated from sheet niobium by the formation of half-cells by deep drawing, followed by trim machining and Electron-Beam Welding (EBW). The welding of half-cells is a delicate...

  13. A LARGE, MASSIVE, ROTATING DISK AROUND AN ISOLATED YOUNG STELLAR OBJECT

    International Nuclear Information System (INIS)

    Quanz, Sascha P.; Beuther, Henrik; Steinacker, Juergen; Linz, Hendrik; Krause, Oliver; Henning, Thomas; Birkmann, Stephan M.; Zhang Qizhou

    2010-01-01

    We present multi-wavelength observations and a radiative transfer model of a newly discovered massive circumstellar disk of gas and dust which is one of the largest disks known today. Seen almost edge-on, the disk is resolved in high-resolution near-infrared (NIR) images and appears as a dark lane of high opacity intersecting a bipolar reflection nebula. Based on molecular line observations, we estimate the distance to the object to be 3.5 kpc. This leads to a size for the dark lane of ∼10,500 AU but due to shadowing effects the true disk size could be smaller. In Spitzer/IRAC 3.6 μm images, the elongated shape of the bipolar reflection nebula is still preserved and the bulk of the flux seems to come from disk regions that can be detected due to the slight inclination of the disk. At longer IRAC wavelengths, the flux is mainly coming from the central regions penetrating directly through the dust lane. Interferometric observations of the dust continuum emission at millimeter wavelengths with the Submillimeter Array confirm this finding as the peak of the unresolved millimeter-emission coincides perfectly with the peak of the Spitzer/IRAC 5.8 μm flux and the center of the dark lane seen in the NIR images. Simultaneously acquired CO data reveal a molecular outflow along the northern part of the reflection nebula which seems to be the outflow cavity. An elongated gaseous disk component is also detected and shows signs of rotation. The emission is perpendicular to the molecular outflow and thus parallel to but even more extended than the dark lane in the NIR images. Based on the dust continuum and the CO observations, we estimate a disk mass of up to a few solar masses depending on the underlying assumptions. Whether the disk-like structure is an actual accretion disk or rather a larger-scale flattened envelope or pseudodisk is difficult to discriminate with the current data set. The existence of HCO + /H 13 CO + emission proves the presence of dense gas in the disk

  14. Whispering Gallery Mode Resonances from Ge Micro-Disks on Suspended Beams

    Directory of Open Access Journals (Sweden)

    Abdelrahman Zaher Al-Attili

    2015-05-01

    Full Text Available Ge is considered to be one of the most promising materials for realizing full monolithic integration of a light source on a silicon (Si photonic chip. Tensile-strain is required to convert Ge into an optical gain material and to reduce the pumping required for population inversion. Several methods of strain application to Ge are proposed in literature, of which the use of free-standing beams fabricated by micro-electro-mechanical systems (MEMS processes are capable of delivering very high strain values. However, it is challenging to make an optical cavity within free-standing Ge beams, and here, we demonstrate the fabrication of a simple cavity while imposing tensile strain by suspension using Ge-On-Insulator (GOI wafers. Ge micro-disks are made on top of suspended SiO$_{2}$ beams by partially removing the supporting Si substrate. According to Raman spectroscopy, a slight tensile strain was applied to the Ge disks through the bending of the SiO2 beams. Whispering-Gallery-Mode (WGM resonances were observed from a disk with a diameter of 3um, consistent with the finite-domain time-difference simulations. The quality (Q factor was 192, and upon increasing the pumping power, the Q-factor was degraded due to the red-shift of Ge direct-gap absorption edge caused by heating.

  15. Continuum Reverberation Mapping of AGN Accretion Disks

    Energy Technology Data Exchange (ETDEWEB)

    Fausnaugh, Michael M. [Department of Astronomy, Ohio State University, Columbus, OH (United States); MIT Kavli Institute for Astrophysics and Space Research, Cambridge, MA (United States); Peterson, Bradley M. [Department of Astronomy, Ohio State University, Columbus, OH (United States); Center for Cosmology and AstroParticle Physics, Ohio State University, Columbus, OH (United States); Space Telescope Science Institute, Baltimore, MD (United States); Starkey, David A. [SUPA Physics and Astronomy, University of St. Andrews, Scotland (United Kingdom); Department of Astronomy, University of Illinois at Urbana-Champaign, Urbana, IL (United States); Horne, Keith, E-mail: faus@mit.edu [SUPA Physics and Astronomy, University of St. Andrews, Scotland (United Kingdom); Collaboration: the AGN STORM Collaboration

    2017-12-05

    We show recent detections of inter-band continuum lags in three AGN (NGC 5548, NGC 2617, and MCG+08-11-011), which provide new constraints on the temperature profiles and absolute sizes of the accretion disks. We find lags larger than would be predicted for standard geometrically thin, optically thick accretion disks by factors of 2.3–3.3. For NGC 5548, the data span UV through optical/near-IR wavelengths, and we are able to discern a steeper temperature profile than the T ~ R{sup −3/4} expected for a standard thin disk. Using a physical model, we are also able to estimate the inclinations of the disks for two objects. These results are similar to those found from gravitational microlensing of strongly lensed quasars, and provide a complementary approach for investigating the accretion disk structure in local, low luminosity AGN.

  16. Chemical evolution of the galactic disk

    International Nuclear Information System (INIS)

    Wyse, R.F.G.; Gilmore, G.

    1987-01-01

    The distribution of enriched material in the stars and gas of their Galaxy contains information pertaining to the chemical evolution of the Milky Way from its formation epoch to the present day, and provides general constraints on theories of galaxy formation. The separate stellar components of the Galaxy cannot readily be understood if treated in isolation, but a reasonably self-consistent model for Galactic chemical evolution may be found if one considers together the chemical properties of the extreme spheroid, thick disk and thin disk populations of the Galaxy. The three major stellar components of the Galaxy are characterized by their distinct spatial distributions, metallicity structure, and kinematics, with the newly-identified thick disk being approximately three times more massive than the classical metal-poor, non-rotating extreme spheroid. Stellar evolution in the thick disk straightforwardly provides the desired pre-enrichment for resolution of the thin disk G dwarf problem

  17. Hydrodynamical winds from a geometrically thin disk

    International Nuclear Information System (INIS)

    Fukue, Jun

    1989-01-01

    Hydrodynamical winds emanating from the surface of a geometrically thin disk under the gravitational field of the central object are examined. The attention is focused on the transonic nature of the flow. For a given configuration of streamlines, the flow fields are divided into three regions: the inner region where the gas near the disk plane is gravitationally bound to form a corona; the intermediate wind region where multiple critical points appear and the gas flows out from the disk passing through critical points; and the outer region where the gas is unbound to escape to infinity without passing through critical points. This behavior of disk winds is due to the shape of the gravitational potential of the central object along the streamline and due to the energy source distribution at the flow base on the disk plane where the potential in finite. (author)

  18. Disk Evolution and the Fate of Water

    Science.gov (United States)

    Hartmann, Lee; Ciesla, Fred; Gressel, Oliver; Alexander, Richard

    2017-10-01

    We review the general theoretical concepts and observational constraints on the distribution and evolution of water vapor and ice in protoplanetary disks, with a focus on the Solar System. Water is expected to freeze out at distances greater than 1-3 AU from solar-type central stars; more precise estimates are difficult to obtain due to uncertainties in the complex processes involved in disk evolution, including dust growth, settling, and radial drift, and the level of turbulence and viscous dissipation within disks. Interferometric observations are now providing constraints on the positions of CO snow lines, but extrapolation to the unresolved regions where water ice sublimates will require much better theoretical understanding of mass and angular momentum transport in disks as well as more refined comparison of observations with sophisticated disk models.

  19. Development of Powered Disk Type Sugar Cane Stubble Saver

    Directory of Open Access Journals (Sweden)

    Radite P.A.S.

    2009-04-01

    Full Text Available The objective of this research was to design, fabricate and test a prototype of sugar cane stubble saver based on powered disk mechanism. In this research, a heavy duty disk plow or disk harrow was used as a rotating knife to cut the sugarcane stubble. The parabolic disk was chosen because it is proven reliable as soil working tools and it is available in the market as spare part of disk plow or disk harrow unit. The prototype was mounted on the four wheel tractor’s three point hitch, and powered by PTO of the tractor. Two kinds of disks were used in these experiments, those were disk with regular edge or plain disk and disk with scalloped edge or scalloped disk. Both disks had diameter of 28 inch. Results of field test showed that powered disk mechanism could satisfy cut sugar cane’s stubble. However, scalloped disk type gave smoother stubble cuts compared to that of plain disk. Plain disk type gave broken stubble cut. Higher rotation (1000 rpm resulted better cuts as compared to lower rotation (500 rpm both either on plain disk and scalloped disk. The developed prototype could work below the soil surface at depth of 5 to 10 cm. With tilt angle setting 20O and disk angle 45O the width of cut was about 25 cm.

  20. Transmission of High Frequency Vibrations in Rotating Systems. Application to Cavitation Detection in Hydraulic Turbines

    Directory of Open Access Journals (Sweden)

    David Valentín

    2018-03-01

    Full Text Available One of the main causes of damage in hydraulic turbines is cavitation. While not all cavitation appearing in a turbine is of a destructive type, erosive cavitation can severely affect the structure, thus increasing maintenance costs and reducing the remaining useful life of the machine. Of all types of cavitation, the maximum erosion occurs when clouds of bubbles collapse on the runner surface (cloud cavitation. When this occurs it is associated with a substantial increase in noise, and vibrations that are propagated everywhere throughout the machine. The generation of these cavitation clouds may occur naturally or it may be the response to a periodic pressure fluctuation, like the rotor/stator interaction in a hydraulic turbine. Erosive bubble cavitation generates high-frequency vibrations that are modulated by the shedding frequency. Therefore, the methods for the detection of erosive cavitation in hydraulic turbines are based on the measurement and demodulation of high-frequency vibrations. In this paper, the feasibility of detecting erosive cavitation in hydraulic turbines is investigated experimentally in a rotating disk system, which represents a simplified hydraulic turbine structure. The test rig used consists of a rotating disk submerged in a tank of water and confined with nearby axial and radial rigid surfaces. The excitation patterns produced by cloud cavitation are reproduced with a PZT (piezoelectric patch located on the disk. These patterns include pseudo-random excitations of different frequency bands modulated by one low carrier frequency, which model the erosive cavitation characteristics. Different types of sensors have been placed in the stationary and in the rotating parts (accelerometers, acoustic emission (AE, and a microphone in order to detect the excitation pattern. The results obtained for all the sensors tested have been compared in detail for the different excitation patterns applied to the disk. With this information

  1. Effect of wind turbine wakes on summer-time wind profiles in the US Great Plains

    Science.gov (United States)

    Rhodes, M. E.; Lundquist, J. K.; Aitken, M.

    2011-12-01

    Wind energy is steadily becoming a significant source of grid electricity in the United States, and the Midwestern United States provides one of the nation's richest wind resources. This study examines the effect of wind turbine wakes on the wind profile in central Iowa. Data were collected using a coherent Doppler LiDAR system located approximately 2.5 rotor diameters north of a row of modern multi-MW wind turbine generators. The prevailing wind direction was from the South allowing the LiDAR to capture wind turbine wake properties; however, a number of periods existed where the LiDAR captured undisturbed flow. The LiDAR system reliably obtained readings up to 200 m above ground level (AGL), spanning the entire rotor disk (~40 m to 120 m AGL) which far surpasses the information provided by traditional wind resource assessment instrumentation. We extract several relevant parameters from the lidar data including: horizontal wind speed, vertical velocity, horizontal turbulence intensity, wind shear, and turbulent kinetic energy (TKE). Each time period at a particular LiDAR measurement height was labeled "wake" or "undisturbed" based on the wind direction at that height. Wake and undisturbed data were averaged separately to create a time-height cross-section averaged day for each parameter. Significant differences between wake and undisturbed data emerge. During the day, wake conditions experience larger values of TKE within the altitudes of the turbine rotor disk while TKE values above the rotor disk are similar between waked and undisturbed conditions. Furthermore, the morning transition of TKE in the atmospheric boundary layer commences earlier during wake conditions than in undisturbed conditions, and the evening decay of TKE persists longer during wake conditions. Waked wind shear is consistently greater than undisturbed periods at the edges of the wind turbine rotor disk (40m & 120m AGL), but especially so during the night where wind shear values during wake

  2. LEP Radio Frequency Copper Cavity

    CERN Multimedia

    The pulse of a particle accelerator. 128 of these radio frequency cavities were positioned around CERN's 27-kilometre LEP ring to accelerate electrons and positrons. The acceleration was produced by microwave electric oscillations at 352 MHz. The electrons and positrons were grouped into bunches, like beads on a string, and the copper sphere at the top stored the microwave energy between the passage of individual bunches. This made for valuable energy savings as it reduced the heat generated in the cavity.

  3. Advanced Hydrogen Turbine Development

    Energy Technology Data Exchange (ETDEWEB)

    Marra, John [Siemens Energy, Inc., Orlando, FL (United States)

    2015-09-30

    Under the sponsorship of the U.S. Department of Energy (DOE) National Energy Technology Laboratories, Siemens has completed the Advanced Hydrogen Turbine Development Program to develop an advanced gas turbine for incorporation into future coal-based Integrated Gasification Combined Cycle (IGCC) plants. All the scheduled DOE Milestones were completed and significant technical progress was made in the development of new technologies and concepts. Advanced computer simulations and modeling, as well as subscale, full scale laboratory, rig and engine testing were utilized to evaluate and select concepts for further development. Program Requirements of: A 3 to 5 percentage point improvement in overall plant combined cycle efficiency when compared to the reference baseline plant; 20 to 30 percent reduction in overall plant capital cost when compared to the reference baseline plant; and NOx emissions of 2 PPM out of the stack. were all met. The program was completed on schedule and within the allotted budget

  4. Probabilistic Design of Wind Turbines

    DEFF Research Database (Denmark)

    Toft, Henrik Stensgaard

    During the last decades, wind turbines have been continuously developed with the aim of maximizing the life cycle benefits (production of electricity) minus the costs of planning, materials, installation, operation & maintenance as well as possible failure. In order to continue this development...... turbines and the central topics considered are statistical load extrapolation of extreme loads during operation and reliability assessment of wind turbine blades. Wind turbines differ from most civil engineering structures by having a control system which highly influences the loading. In the literature......, methods for estimating the extreme load-effects on a wind turbine during operation, where the control system is active, have been proposed. But these methods and thereby the estimated loads are often subjected to a significant uncertainty which influences the reliability of the wind turbine...

  5. Reliability Analysis of Wind Turbines

    DEFF Research Database (Denmark)

    Toft, Henrik Stensgaard; Sørensen, John Dalsgaard

    2008-01-01

    In order to minimise the total expected life-cycle costs of a wind turbine it is important to estimate the reliability level for all components in the wind turbine. This paper deals with reliability analysis for the tower and blades of onshore wind turbines placed in a wind farm. The limit states...... consideres are in the ultimate limit state (ULS) extreme conditions in the standstill position and extreme conditions during operating. For wind turbines, where the magnitude of the loads is influenced by the control system, the ultimate limit state can occur in both cases. In the fatigue limit state (FLS......) the reliability level for a wind turbine placed in a wind farm is considered, and wake effects from neighbouring wind turbines is taken into account. An illustrative example with calculation of the reliability for mudline bending of the tower is considered. In the example the design is determined according...

  6. Steam turbines for the future

    International Nuclear Information System (INIS)

    Trassl, W.

    1988-01-01

    Approximately 75% of the electrical energy produced in the world is generated in power plants with steam turbines (fossil and nuclear). Although gas turbines are increasingly applied in combined cycle power plants, not much will change in this matter in the future. As far as the steam parameters and the maximum unit output are concerned, a certain consolidation was noted during the past decades. The standard of development and mathematical penetration of the various steam turbine components is very high today and is applied in the entire field: For saturated steam turbines in nuclear power plants and for steam turbines without reheat, with reheat and with double reheat in fossil-fired power plants and for steam turbines with and without reheat in combined cycle power plants. (orig.) [de

  7. Wind Turbine Providing Grid Support

    DEFF Research Database (Denmark)

    2011-01-01

    changing the operation of the wind turbine to a more efficient working point.; When the rotational speed of the rotor reaches a minimum value, the wind turbine enters a recovery period to re-accelerate the rotor to the nominal rotational speed while further contributing to the stability of the electrical......A variable speed wind turbine is arranged to provide additional electrical power to counteract non-periodic disturbances in an electrical grid. A controller monitors events indicating a need to increase the electrical output power from the wind turbine to the electrical grid. The controller...... is arranged to control the wind turbine as follows: after an indicating event has been detected, the wind turbine enters an overproduction period in which the electrical output power is increased, wherein the additional electrical output power is taken from kinetic energy stored in the rotor and without...

  8. Oxidation of Alumina-Forming MAX Phases in Turbine Environments

    Science.gov (United States)

    Smialek, James; Garg, Anita; Harder, Bryan; Nesbitt, James; Gabb, Timothy; Gray, SImon

    2017-01-01

    Protective coatings for high temperature turbine components are based on YSZ thermal barriers and oxidation resistant, alumina-forming NiAl or NiCoCrAlY bond coats. Ti2AlC and Cr2AlC MAX phases are thus of special interest because of good oxidation resistance and CTE that can match Al2O3 and YSZ. Their alumina scales grow according to cubic kinetics due to grain growth in the scale, with initial heating dominated by fast TiO2 growth. Protective cubic kinetics are also found in high pressure burner rig tests of MAXthal 211 Ti2AlC, but with reduced rates due to volatile TiO(OH)2 formation in water vapor. YSZ-coatings on bulk Ti2AlC exhibit remarkable durability up to 1300C in furnace tests and at least a 25x life advantage compared to superalloys. At another extreme, Cr2AlC is resistant to low temperature Na2SO4 hot corrosion and exhibits thermal cycling stability bonded to a superalloy disk material. Accordingly, sputtered Cr2AlC coatings on disk specimens prevented hot corrosion detriments on LCF. Breakaway oxidation (Ti2AlC), scale spallation (Cr2AlC), interdiffusion, and processing as coatings still present serious challenges. However the basic properties of MAX phases provide some unusual opportunities for use in high temperature turbines.

  9. THE DARK DISK OF THE MILKY WAY

    International Nuclear Information System (INIS)

    Purcell, Chris W.; Bullock, James S.; Kaplinghat, Manoj

    2009-01-01

    Massive satellite accretions onto early galactic disks can lead to the deposition of dark matter in disk-like configurations that co-rotate with the galaxy. This phenomenon has potentially dramatic consequences for dark matter detection experiments. We utilize focused, high-resolution simulations of accretion events onto disks designed to be Galaxy analogues, and compare the resultant disks to the morphological and kinematic properties of the Milky Way's thick disk in order to bracket the range of co-rotating accreted dark matter. In agreement with previous results, we find that the Milky Way's merger history must have been unusually quiescent compared to median Λ cold dark matter expectations and, therefore, its dark disk must be relatively small: the fraction of accreted dark disk material near the Sun is about 20% of the host halo density or smaller and the co-rotating dark matter fraction near the Sun, defined as particles moving with a rotational velocity lag less than 50 km s -1 , is enhanced by about 30% or less compared to a standard halo model. Such a dark disk could contribute dominantly to the low energy (of order keV for a dark matter particle with mass 100 GeV) nuclear recoil event rate of direct detection experiments, but it will not change the likelihood of detection significantly. These dark disks provide testable predictions of weakly interacting massive particle dark matter models and should be considered in detailed comparisons to experimental data. Our findings suggest that the dark disk of the Milky Way may provide a detectable signal for indirect detection experiments, contributing up to about 25% of the dark matter self-annihilation signal in the direction of the center of the Galaxy, lending the signal a noticeably oblate morphology.

  10. Equilibrium figures for beta Lyrae type disks

    International Nuclear Information System (INIS)

    Wilson, R.E.

    1981-01-01

    Accumulated evidence for a geometrically and optically thick disk in the β Lyrae system has now established the disk's basic external configuration. Since the disk has been constant in its main properties over the historical interval of β Lyrae observations and also seems to have a basically well-defined photosphere, it is now time to being consideration of its sturcture. Here, we compute equilibrium figures for self-gravitating disks around stars in binary systems as a start toward eventual computation of complete disk models. A key role is played by centrifugally limited rotation of the central star, which would naturally arise late in the rapid phase of mass transfer. Beta Lyrae is thus postulated to be a double-contact binary, which makes possible nonarbitrary separation of star and disk into separate structures. The computed equilibrium figures are three-dimensional, as the gravitation of the second star is included. Under the approximation that the gravitational potential of the disk is that of a thin wire and that the local disk angular velocity is proportional to u/sup n/ (u = distance from rotation axis), we comptue the total potential and locate equipotential surfaces. The centrifugal potential is written in a particularly convenient form which permits one to change the rotation law discontinuously (for example, at the star-disk coupling point) while ensuring that centrifugal potential and centrifigual force are continuous functions of position. With such a one-parameter rotation law, one can find equilibrium disk figures with dimensions very similar to those found in β Lyrae, but considerations of internal consistency demand at least a two-parameter law

  11. TESLA superconducting RF cavity development

    International Nuclear Information System (INIS)

    Koepke, K.

    1995-01-01

    The TESLA collaboration has made steady progress since its first official meeting at Cornell in 1990. The infrastructure necessary to assemble and test superconducting rf cavities has been installed at the TESLA Test Facility (TTF) at DESY. 5-cell, 1.3 GHz cavities have been fabricated and have reached accelerating fields of 25 MV/m. Full sized 9-cell copper cavities of TESLA geometry have been measured to verify the higher order modes present and to evaluate HOM coupling designs. The design of the TESLA 9-cell cavity has been finalized and industry has started delivery. Two prototype 9-cell niobium cavities in their first tests have reached accelerating fields of 10 MV/m and 15 MV/m in a vertical dewar after high peak power (HPP) conditioning. The first 12 m TESLA cryomodule that will house 8 9-cell cavities is scheduled to be delivered in Spring 1995. A design report for the TTF is in progress. The TTF test linac is scheduled to be commissioned in 1996/1997. (orig.)

  12. Performance assessment of Darrieus wind turbine with symmetric and cambered airfoils

    Energy Technology Data Exchange (ETDEWEB)

    Cisse, H.; Trifu, O.; Paraschivoiu, I. [Ecole Polytechnique, Montreal, PQ (Canada). Dept. de Genie Mecanique

    2007-07-01

    This paper outlined the wind turbine and design software used to predict the flow conditions and performance of a straight-bladed Darrieus wind turbine. Three different blade sections were considered, notably the NACA 0018; the SNLA NLF 18/50 symmetrical airfoil; and the FX63-137 cambered airfoil. The numerical predictions of the flow conditions during the operation of the rotors were also presented. Torque yield for each blade section under a variety of operating conditions was presented. The numerical software program used in the study was based on a double-multiple streamtube model which considered a partition of the rotor in streamtubes and considered each of the 2 blade elements as an actuator disk. The actuator disk theory was based on a theory of momentum conservation. Wind velocities were determined in order to calculate forces acting on the actuator disks. A second set of equations was used to determine the forces acting on the upwind and downwind blade elements. Equations were also derived for the downwind interference factor. The following 3 main sets of data were used: (1) a geometry definition of the wind turbine; (2) operational conditions; and (3) main control parameters. Results of the study showed that the cambered airfoil blade section produced 10 times more torque in turbine starting conditions than the NACA 0018. Laminar airfoil lift to drag ratio at low angles of attack, and the use of appropriate Reynolds numbers resulted in higher efficiency. The large static stall angle of the cambered airfoil allowed higher power outputs than symmetrical airfoils. It was concluded that the starting torque of a Darrieus turbine can be increased by using a cambered blade section. 13 refs., 19 figs.

  13. Superconducting wind turbine generators

    International Nuclear Information System (INIS)

    Abrahamsen, A B; Seiler, E; Zirngibl, T; Andersen, N H; Mijatovic, N; Traeholt, C; Pedersen, N F; Oestergaard, J; Noergaard, P B

    2010-01-01

    We have examined the potential of 10 MW superconducting direct drive generators to enter the European offshore wind power market and estimated that the production of about 1200 superconducting turbines until 2030 would correspond to 10% of the EU offshore market. The expected properties of future offshore turbines of 8 and 10 MW have been determined from an up-scaling of an existing 5 MW turbine and the necessary properties of the superconducting drive train are discussed. We have found that the absence of the gear box is the main benefit and the reduced weight and size is secondary. However, the main challenge of the superconducting direct drive technology is to prove that the reliability is superior to the alternative drive trains based on gearboxes or permanent magnets. A strategy of successive testing of superconducting direct drive trains in real wind turbines of 10 kW, 100 kW, 1 MW and 10 MW is suggested to secure the accumulation of reliability experience. Finally, the quantities of high temperature superconducting tape needed for a 10 kW and an extreme high field 10 MW generator are found to be 7.5 km and 1500 km, respectively. A more realistic estimate is 200-300 km of tape per 10 MW generator and it is concluded that the present production capacity of coated conductors must be increased by a factor of 36 by 2020, resulting in a ten times lower price of the tape in order to reach a realistic price level for the superconducting drive train.

  14. Gas turbine premixing systems

    Science.gov (United States)

    Kraemer, Gilbert Otto; Varatharajan, Balachandar; Evulet, Andrei Tristan; Yilmaz, Ertan; Lacy, Benjamin Paul

    2013-12-31

    Methods and systems are provided for premixing combustion fuel and air within gas turbines. In one embodiment, a combustor includes an upstream mixing panel configured to direct compressed air and combustion fuel through premixing zone to form a fuel-air mixture. The combustor includes a downstream mixing panel configured to mix additional combustion fuel with the fule-air mixture to form a combustion mixture.

  15. Airfoils for wind turbine

    Science.gov (United States)

    Tangler, James L.; Somers, Dan M.

    1996-01-01

    Airfoils for the blade of a wind turbine wherein each airfoil is characterized by a thickness in a range from 16%-24% and a maximum lift coefficient designed to be largely insensitive to roughness effects. The airfoils include a family of airfoils for a blade 15 to 25 meters in length, a family of airfoils for a blade 1 to 5 meters in length, and a family of airfoils for a blade 5 to 10 meters in length.

  16. Air Turbines for Wave Energy Conversion

    Directory of Open Access Journals (Sweden)

    Manabu Takao

    2012-01-01

    Full Text Available This paper describes the present status of the art on air turbines, which could be used for wave energy conversion. The air turbines included in the paper are as follows: Wells type turbines, impulse turbines, radial turbines, cross-flow turbine, and Savonius turbine. The overall performances of the turbines under irregular wave conditions, which typically occur in the sea, have been compared by numerical simulation and sea trial. As a result, under irregular wave conditions it is found that the running and starting characteristics of the impulse type turbines could be superior to those of the Wells turbine. Moreover, as the current challenge on turbine technology, the authors explain a twin-impulse turbine topology for wave energy conversion.

  17. Introduction to wind turbine aerodynamics

    CERN Document Server

    Schaffarczyk, Alois Peter

    2014-01-01

    Wind-Turbine Aerodynamics is a self-contained textbook which shows how to come from the basics of fluid mechanics to modern wind turbine blade design. It presents a fundamentals of fluid dynamics and inflow conditions, and gives a extensive introduction into theories describing the aerodynamics of wind turbines. After introducing experiments the book applies the knowledge to explore the impact on blade design.The book is an introduction for professionals and students of very varying levels.

  18. Tornado type wind turbines

    Science.gov (United States)

    Hsu, Cheng-Ting

    1984-01-01

    A tornado type wind turbine has a vertically disposed wind collecting tower with spaced apart inner and outer walls and a central bore. The upper end of the tower is open while the lower end of the structure is in communication with a wind intake chamber. An opening in the wind chamber is positioned over a turbine which is in driving communication with an electrical generator. An opening between the inner and outer walls at the lower end of the tower permits radially flowing air to enter the space between the inner and outer walls while a vertically disposed opening in the wind collecting tower permits tangentially flowing air to enter the central bore. A porous portion of the inner wall permits the radially flowing air to interact with the tangentially flowing air so as to create an intensified vortex flow which exits out of the top opening of the tower so as to create a low pressure core and thus draw air through the opening of the wind intake chamber so as to drive the turbine.

  19. Composite wind turbine towers

    Energy Technology Data Exchange (ETDEWEB)

    Polyzois, D. [Manitoba Univ., Winnipeg, MB (Canada). Dept. of Civil Engineering

    2008-07-01

    This paper discussed experiments conducted to optimized the advanced composite materials such as fiberglass reinforced plastics (FRP) used to fabricate wind turbine towers. FRP materials are used in tubular steel, lattice, guyed, and reinforced concrete towers. The towers and turbine blades are transported in segments and assembled on-site, sometimes in offshore or remote locations.The FRP composites are used to build towers with a high strength-to-weight ratio as well as to provide resistance to chemical attacks and corrosion. Use of the materials has resulted in towers that do not require heavy installation equipment. Experimental programs were conducted to verify the structural behaviour of the tower structure's individual-scaled cells as well as to evaluate the performance of multi-cell assemblies. Joint assembly designs were optimized, and a filament winding machine was used to conduct the experimental study and to test individual cells. Failure mode analyses were conducted to determine local buckling and shear rupture. Tension, compression, and shear properties of the FRP materials were tested experimentally, and data from the test were then used to develop finite element models of the composite towers as well as to obtain load deflection curves and tip oscillation data. A case study of a 750 kW wind turbine in Churchill, Manitoba was used to test the design. tabs., figs.

  20. Multiple piece turbine engine airfoil with a structural spar

    Science.gov (United States)

    Vance, Steven J [Orlando, FL

    2011-10-11

    A multiple piece turbine airfoil having an outer shell with an airfoil tip that is attached to a root with an internal structural spar is disclosed. The root may be formed from first and second sections that include an internal cavity configured to receive and secure the one or more components forming the generally elongated airfoil. The internal structural spar may be attached to an airfoil tip and place the generally elongated airfoil in compression. The configuration enables each component to be formed from different materials to reduce the cost of the materials and to optimize the choice of material for each component.