WorldWideScience

Sample records for wind interactions appendix

  1. Design Mining Interacting Wind Turbines.

    Science.gov (United States)

    Preen, Richard J; Bull, Larry

    2016-01-01

    An initial study has recently been presented of surrogate-assisted evolutionary algorithms used to design vertical-axis wind turbines wherein candidate prototypes are evaluated under fan-generated wind conditions after being physically instantiated by a 3D printer. Unlike other approaches, such as computational fluid dynamics simulations, no mathematical formulations were used and no model assumptions were made. This paper extends that work by exploring alternative surrogate modelling and evolutionary techniques. The accuracy of various modelling algorithms used to estimate the fitness of evaluated individuals from the initial experiments is compared. The effect of temporally windowing surrogate model training samples is explored. A surrogate-assisted approach based on an enhanced local search is introduced; and alternative coevolution collaboration schemes are examined.

  2. The Interaction of Ocean Waves and Wind

    Science.gov (United States)

    Janssen, Peter

    2004-10-01

    Describing in detail the two-way interaction between wind and ocean waves, this book discusses ocean wave evolution in accordance with the energy balance equation. An extensive overview of nonlinear transfer is given, and the role of four-wave interactions in the generation of extreme events as well as the effects on ocean circulation is included. The volume will interest ocean wave modellers, physicists, applied mathematicians, and engineers.

  3. Wind Turbine Converter Control Interaction with Complex Wind Farm Systems

    DEFF Research Database (Denmark)

    Kocewiak, Lukasz Hubert; Hjerrild, Jesper; Bak, Claus Leth

    2013-01-01

    in this study. It is shown that wind farm components, such as long high-voltage alternating current cables and park transformers, can introduce significant low-frequency series resonances seen from the wind turbine terminals that can affect wind turbine control system operation and overall wind farm stability...

  4. Studying Wind Energy/Bird Interactions: A Guidance Document

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, R. [California Energy Commission (US); Morrison, M. [California State Univ., Sacramento, CA (US); Sinclair, K. [Dept. of Energy/National Renewable Energy Lab. (US); Strickland, D. [WEST, Inc. (US)

    1999-12-01

    This guidance document is a product of the Avian Subcommittee of the National Wind Coordinating Committee (NWCC). The NWCC was formed to better understand and promote responsible, credible, and comparable avian/wind energy interaction studies. Bird mortality is a concern and wind power is a potential clean and green source of electricity, making study of wind energy/bird interactions essential. This document provides an overview for regulators and stakeholders concerned with wind energy/bird interactions, as well as a more technical discussion of the basic concepts and tools for studying such interactions.

  5. Interactions in Massive Colliding Wind Binaries

    Directory of Open Access Journals (Sweden)

    Michael F. Corcoran

    2012-03-01

    Full Text Available There are observational difficulties determining dynamical masses of binary star components in the upper HR diagram both due to the scarcity of massive binary systems and spectral and photometric contamination produced by the strong wind outflows in these systems. We discuss how variable X-ray emission in these systems produced by wind-wind collisions in massive binaries can be used to constrain the system parameters, with application to two important massive binaries, Eta Carinae and WR 140.

  6. Interacting Winds in Eclipsing Symbiotic Systems – The Case Study ...

    Indian Academy of Sciences (India)

    The most adopted physical modeling for many symbiotic stars is that of interacting binaries: a cool giant, a hot .... envelopes the area behind the hot component; and if mw > 1, the hot wind predom- inates the cool wind. ...... Tomov, N., Tomova, M. 2001, Astrophysics and Space Science, 278, 311. Torbett, M. V., Campbell, B.

  7. Interactions between exoplanets and the winds of young stars

    Directory of Open Access Journals (Sweden)

    Vidotto A. A.

    2014-01-01

    Full Text Available The topology of the magnetic field of young stars is important not only for the investigation of magnetospheric accretion, but also responsible in shaping the large-scale structure of stellar winds, which are crucial for regulating the rotation evolution of stars. Because winds of young stars are believed to have enhanced mass-loss rates compared to those of cool, main-sequence stars, the interaction of winds with newborn exoplanets might affect the early evolution of planetary systems. This interaction can also give rise to observational signatures which could be used as a way to detect young planets, while simultaneously probing for the presence of their still elusive magnetic fields. Here, we investigate the interaction between winds of young stars and hypothetical planets. For that, we model the stellar winds by means of 3D numerical magnetohydrodynamic simulations. Although these models adopt simplified topologies of the stellar magnetic field (dipolar fields that are misaligned with the rotation axis of the star, we show that asymmetric field topologies can lead to an enhancement of the stellar wind power, resulting not only in an enhancement of angular momentum losses, but also intensifying and rotationally modulating the wind interactions with exoplanets.

  8. Nonlinear Interactions Between Oblique Wind Waves

    Science.gov (United States)

    2015-08-01

    of difference modes when λ = O(1) Equation (87) shows that the amplitudes of the first N − 2 difference modes grow exponentially, Adn = adnexp(κdnt̄...for 1 ≤ n ≤ N−2. (96) Their growth rates, κdn, and initial amplitudes, adn , become κdn = κ ∗ s + nκp, (97) adn = ϕ ∗ dn apad(n−1)I (n) d with ad0 = −a...p, AdN ), (101) AdN = −ϕdNG−N (t̄|Ap, Ad(N−1)), (102) with ad(N−1) defined by (98) and G ± n given by (D-3) in Appendix D. The above equations

  9. Solar wind stream interaction regions throughout the heliosphere

    Science.gov (United States)

    Richardson, Ian G.

    2018-01-01

    This paper focuses on the interactions between the fast solar wind from coronal holes and the intervening slower solar wind, leading to the creation of stream interaction regions that corotate with the Sun and may persist for many solar rotations. Stream interaction regions have been observed near 1 AU, in the inner heliosphere (at ˜ 0.3-1 AU) by the Helios spacecraft, in the outer and distant heliosphere by the Pioneer 10 and 11 and Voyager 1 and 2 spacecraft, and out of the ecliptic by Ulysses, and these observations are reviewed. Stream interaction regions accelerate energetic particles, modulate the intensity of Galactic cosmic rays and generate enhanced geomagnetic activity. The remote detection of interaction regions using interplanetary scintillation and white-light imaging, and MHD modeling of interaction regions will also be discussed.

  10. Solar wind and its interaction with the Earth magnetosphere

    International Nuclear Information System (INIS)

    Grib, S.A.

    1978-01-01

    A critical review is given regarding the research of the stationary and non-stationary interaction of the solar wind with the Earth magnetosphere. Highlighted is the significance of the interplanetary magnetic field in the non-stationary movement of the solar wind flux. The problem of the solar wind shock waves interaction with the ''bow wave-Earth's magnetosphere'' system is being solved. Considered are the secondary phenomena, as a result of which the depression-type wave occurs, that lowers the pressure on the Earth's maanetosphere. The law, governing the movement of the magnetosphere subsolar point during the abrupt start of a geomagnetic storm has been discovered. Stationary circumvention of the magnetosphere by the solar wind flux is well described by the gas dynamic theory of the hypersonic flux. Non-stationary interaction of the solar wind shock waves with the magnetosphere is magnetohydrodynamic. It is pointed out, that the problems under consideration are important for the forecasting of strong geomagnetic perturbations on the basis of cosmic observations

  11. The Character of the Solar Wind, Surface Interactions, and Water

    Science.gov (United States)

    Farrell, William M.

    2011-01-01

    We discuss the key characteristics of the proton-rich solar wind and describe how it may interact with the lunar surface. We suggest that solar wind can be both a source and loss of water/OH related volatiles, and review models showing both possibilities. Energy from the Sun in the form of radiation and solar wind plasma are in constant interaction with the lunar surface. As such, there is a solar-lunar energy connection, where solar energy and matter are continually bombarding the lunar surface, acting at the largest scale to erode the surface at 0.2 Angstroms per year via ion sputtering [1]. Figure 1 illustrates this dynamically Sun-Moon system.

  12. Interaction of the solar wind with comets: a Rosetta perspective.

    Science.gov (United States)

    Glassmeier, Karl-Heinz

    2017-07-13

    The Rosetta mission provides an unprecedented possibility to study the interaction of comets with the solar wind. As the spacecraft accompanies comet 67P/Churyumov-Gerasimenko from its very low-activity stage through its perihelion phase, the physics of mass loading is witnessed for various activity levels of the nucleus. While observations at other comets provided snapshots of the interaction region and its various plasma boundaries, Rosetta observations allow a detailed study of the temporal evolution of the innermost cometary magnetosphere. Owing to the short passage time of the solar wind through the interaction region, plasma instabilities such as ring--beam and non-gyrotropic instabilities are of less importance during the early life of the magnetosphere. Large-amplitude ultra-low-frequency (ULF) waves, the 'singing' of the comet, is probably due to a modified ion Weibel instability. This instability drives a cross-field current of implanted cometary ions unstable. The initial pick-up of these ions causes a major deflection of the solar wind protons. Proton deflection, cross-field current and the instability induce a threefold structure of the innermost interaction region with the characteristic Mach cone and Whistler wings as stationary interaction signatures as well as the ULF waves representing the dynamic aspect of the interaction.This article is part of the themed issue 'Cometary science after Rosetta'. © 2017 The Authors.

  13. Interaction of the solar wind with comets: a Rosetta perspective

    Science.gov (United States)

    Glassmeier, Karl-Heinz

    2017-05-01

    The Rosetta mission provides an unprecedented possibility to study the interaction of comets with the solar wind. As the spacecraft accompanies comet 67P/Churyumov-Gerasimenko from its very low-activity stage through its perihelion phase, the physics of mass loading is witnessed for various activity levels of the nucleus. While observations at other comets provided snapshots of the interaction region and its various plasma boundaries, Rosetta observations allow a detailed study of the temporal evolution of the innermost cometary magnetosphere. Owing to the short passage time of the solar wind through the interaction region, plasma instabilities such as ring-beam and non-gyrotropic instabilities are of less importance during the early life of the magnetosphere. Large-amplitude ultra-low-frequency (ULF) waves, the `singing' of the comet, is probably due to a modified ion Weibel instability. This instability drives a cross-field current of implanted cometary ions unstable. The initial pick-up of these ions causes a major deflection of the solar wind protons. Proton deflection, cross-field current and the instability induce a threefold structure of the innermost interaction region with the characteristic Mach cone and Whistler wings as stationary interaction signatures as well as the ULF waves representing the dynamic aspect of the interaction. This article is part of the themed issue 'Cometary science after Rosetta'.

  14. Flank solar wind interaction. Annual report, June 1991-July 1992

    International Nuclear Information System (INIS)

    Moses, S.L.; Greenstadt, E.W.

    1992-08-01

    This report summarizes the results of the first 12 months of our program to study the interaction of the Earth's magnetosphere with the solar wind on the far flanks of the bow shock. This study employs data from the ISEE-3 spacecraft during its traversals of the Earth's magnetotail and correlative data from spacecraft monitoring the solar wind upstream. Our main effort to date has involved assembling data sets and developing new plotting programs. Two talks were given at the Spring Meeting of the American Geophysical Union describing our initial results from analyzing data from the far flank foreshock and magnetosheath. The following sections summarize our results

  15. Interaction between main components in wind farms

    DEFF Research Database (Denmark)

    Holdyk, Andrzej; Koldby, Erik

    sensitivity studies on almost any electrical circuit as the method allows changing any parameters of both, circuit and the simulation. The method is relatively time consuming and error-prone and therefore is recommended only when built-in ATP-EMTP methods cannot be used. Employing the developed method...... interaction studies in electromagnetic transients programmes, as shown in this work, requires component models for medium and high frequency studies. Although modern EMT programs contain accurate wide-band models of, e.g. cables, which can be used successfully in variety of transient studies, there is still...... a lack of wide-band models of transformers. Traditionally, black-box models made using dedicated, non-commercial measurement systems were used for that purpose. This study shows how to develop wide-band, linear black-box model of a linear multiport system using commercial off-the-shelf sweep frequency...

  16. Dynamic Analysis of Wind Turbines Including Soil-Structure Interaction

    DEFF Research Database (Denmark)

    Harte, M.; Basu, B.; Nielsen, Søren R.K.

    2012-01-01

    blades and includes the effect of centrifugal stiffening due to rotation. The foundation of the structure is modeled as a rigid gravity based foundation with two DOF whose movement is related to the surrounding soil by means of complex impedance functions generated using cone model. Transfer functions...... for displacement of the turbine system are obtained and the modal frequencies of the combined turbine-foundation system are estimated. Simulations are presented for the MDOF turbine structure subjected to wind loading for different soil stiffness conditions. Steady state and turbulent wind loading, developed using...... blade element momentum theory and the Kaimal spectrum, have been considered. Soil stiffness and damping properties acquired from DNV/Risø standards are used as a comparison. The soil-structure interaction is shown to affect the response of the wind turbine. This is examined in terms of the turbine...

  17. The variable nature of the comet-solar wind interaction

    International Nuclear Information System (INIS)

    Flammer, K.R.

    1988-01-01

    The different modes of interaction of the solar wind with a Halley-type comet as it approaches the sun are discussed. At large heliocentric distances the solar wind penetrates unimpeded onto the surface of the comet nucleus. This causes electrostatic charging and expulsion of fine dust from the comet surface; a process which is modulated by the local solar wind flux. The observed irregular brightness variation of comet Halley between 11 and 8 AU (inbound) are explained in terms of this mechanism. As the comet moves closer to the sun (within 4 AU), mass loading of the solar wind by the heavy cometary ions causes the flow to slow down, thereby enhancing the convected interplanetary magnetic field significantly. This magnetic field enhancement is the earliest and most sensitive signature associated with the solar wind mass loading. Still farther in (≤ 3 AU), as the mass loading approaches a critical value, a weak collisionless standing shock forms, which recedes upstream of the nucleus as the comet approaches the sun. The cometary atmosphere becomes dense enough so that a well-defined ionopause forms which separates the cometary ionospheric plasma from the contaminated solar wind plasma only when the comet is within ∼ 2.2 AU from the sun. The stability of the ionopause is examined under the framework of linear magnetohydrodynamic taking into account the effects of ion-neutral drag, sources, curvature and compressibility. Both Kelvin-Helmholtz and Rayleigh Taylor modes are excited. The growth rates of these modes are determined from various shears and density jumps at the ionopause and under different solar wind conditions. A quasi-linear theory is then used to examine the evolution of the unstable modes to finite amplitudes

  18. Interactive 3D geodesign tool for multidisciplinary wind turbine planning.

    Science.gov (United States)

    Rafiee, Azarakhsh; Van der Male, Pim; Dias, Eduardo; Scholten, Henk

    2018-01-01

    Wind turbine site planning is a multidisciplinary task comprising of several stakeholder groups from different domains and with different priorities. An information system capable of integrating the knowledge on the multiple aspects of a wind turbine plays a crucial role on providing a common picture to the involved groups. In this study, we have developed an interactive and intuitive 3D system (Falcon) for planning wind turbine locations. This system supports iterative design loops (wind turbine configurations), based on the emerging field of geodesign. The integration of GIS, game engine and the analytical models has resulted in an interactive platform with real-time feedback on the multiple wind turbine aspects which performs efficiently for different use cases and different environmental settings. The implementation of tiling techniques and open standard web services support flexible and on-the-fly loading and querying of different (massive) geospatial elements from different resources. This boosts data accessibility and interoperability that are of high importance in a multidisciplinary process. The incorporation of the analytical models in Falcon makes this system independent from external tools for different environmental impacts estimations and results in a unified platform for performing different environmental analysis in every stage of the scenario design. Game engine techniques, such as collision detection, are applied in Falcon for the real-time implementation of different environmental models (e.g. noise and visibility). The interactivity and real-time performance of Falcon in any location in the whole country assist the stakeholders in the seamless exploration of various scenarios and their resulting environmental effects and provides a scope for an interwoven discussion process. The flexible architecture of the system enables the effortless application of Falcon in other countries, conditional to input data availability. The embedded open web

  19. Solar-wind interactions: nature and composition of lunar atmosphere

    International Nuclear Information System (INIS)

    Mukherjee, N.R.

    1975-01-01

    The solar wind interacts directly with the lunar surface material resulting in an essentially complete absorption of the corpuscles producing no upstream bowshock but a cavity downstream from the Moon. The main source of most neutral species of the atmosphere, except probably 40 Ar, is the solar-wind interaction products. The other sources which appear to be minor contributors to the atmosphere are the interaction products of cosmic from the Moon. The main source of most neutral species of the atmosphere, except probably 40 Ar, is the solar-wind in solar-wind protons contribute to the atmosphere as hydrogen molecules rather than atoms. Only on the basis of the solar-wind protons, alpha particles and ions of oxygen and carbon, the atmospheric species concentration (cm -3 ) near the lunar surface at 300K are as follows: H 2 3.3 to 9.9 x 10 3 , He2.4 to 4.7 x 10 3 ; He3.7; OH 0.25; H 2 O 0.24; and O 2 , O, CO, CO 2 and CH 4 in concentrations smaller than H 2 . Whatever the source, the OH and H 2 O concentrations in the atmosphere are about the same. The calculated concentrations are in good agreement with the observations by the Apollo 17 lunar surface mass spectrometer and the Apollo 17 orbital UV spectrometer. At the time of sample collection from the Moon, the hydrogen content in the trapped gas layer of the lunar surface material was partly as hydrogen atoms and partly as hydrogen molecules, but at the time of sample analysis, hydrogen was mostly in molecular form. The H 2 O content at the time of sample analysis was only a few parts per million by weight

  20. Wind plant interaction with series-compensated power systems

    Science.gov (United States)

    Ramamurthy, Jayanth R.

    Wind power based generation has been rapidly growing world-wide during the recent past. In order to transmit large amounts of wind power over long distances, system planners may often add series compensation to existing transmission lines owing to several benefits such as improved steady-state power transfer limit, improved transient stability, and efficient utilization of transmission infrastructure. Application of series capacitors has posed resonant interaction concerns such as through subsynchronous resonance (SSR) with conventional turbine-generators. Wind turbine-generators may also be susceptible to such resonant interactions. However, not much information is available in literature and even engineering standards are yet to address these issues. The motivation problem for this research is based on an actual system switching event that resulted in undamped oscillations in a 345-kV series-compensated, typical ring-bus power system configuration. Based on time-domain ATP (Alternative Transients Program) modeling, simulations and analysis of system event records, the occurrence of subsynchronous interactions within the existing 345-kV series-compensated power system has been investigated. Effects of various small-signal and large-signal power system disturbances with both identical and non-identical wind turbine parameters (such as with a statistical-spread) has been evaluated. Effect of parameter variations on subsynchronous oscillations has been quantified using 3D-DFT plots and the oscillations have been identified as due to electrical self-excitation effects, rather than torsional interaction. Further, the generator no-load reactance and the rotor-side converter inner-loop controller gains have been identified as bearing maximum sensitivity to either damping or exacerbating the self-excited oscillations. A higher-order spectral analysis method based on modified Prony estimation has been successfully applied to the field records identifying dominant 9.79 Hz

  1. Theoretical calculations of interactions between urban breezes and mountain slope winds in the presence of basic-state wind

    Science.gov (United States)

    Seo, Jaemyeong Mango; Ganbat, Gantuya; Han, Ji-Young; Baik, Jong-Jin

    2017-02-01

    Many big cities around the world are located near mountains. In city-mountain regions, thermally and topographically forced local winds are produced and they affect the transport of pollutants emitted into the urban atmosphere. A better understanding of the dynamics of thermally and topographically forced local winds is necessary to improve the prediction of local winds and to cope with environmental problems. In this study, we theoretically examine the interactions of urban breezes with mountain slope winds in the presence of basic-state wind within the context of the response of a stably stratified atmosphere to prescribed thermal and mechanical forcing. The interactions between urban breezes and mountain slope winds are viewed through the linear superposition of individual analytical solutions for urban thermal forcing, mountain thermal forcing, and mountain mechanical forcing. A setting is considered in which a city is located downwind of a mountain. In the nighttime, in the mountain-side urban area, surface/near-surface horizontal flows induced by mountain cooling and mountain mechanical forcing cooperatively interact with urban breezes, resulting in strengthened winds. In the daytime, in the urban area, surface/near-surface horizontal flows induced by mountain heating are opposed to urban breezes, giving rise to weakened winds. It is shown that the degree of interactions between urban breezes and mountain slope winds is sensitive to mountain height and basic-state wind speed. Particularly, a change in basic-state wind speed affects not only the strength of thermally and mechanically induced flows (internal gravity waves) but also their vertical wavelength and decaying rate. The examination of a case in a setting in which a city is located upwind of a mountain reveals that basic-state wind direction is an important factor that significantly affects the interactions of urban breezes with mountain slope winds.

  2. Dynamical instabilities in magnetohydrodynamic wind-cloud interactions

    Science.gov (United States)

    Banda-Barragan, Wladimir Eduardo; Parkin, Elliot Ross; Crocker, Roland M.; Federrath, Christoph; Bicknell, Geoffrey Vincent

    2015-08-01

    We report the results from a comprehensive numerical study that investigates the role of dynamical instabilities in magnetohydrodynamic interactions between winds and spherical clouds in the interstellar medium. The growth of Kelvin-Helmholtz (KH) and Rayleigh-Taylor (RT) instabilities at interfaces between wind and cloud material is responsible for the disruption of clouds and the formation of filamentary tails. We show how different strengths and orientations of the initial magnetic field affect the development of unstable modes and the ultimate morphology of these filaments. In the weak field limit, for example, KH instabilities developing at the flanks of clouds are dominant, whilst they are suppressed when stronger fields are considered. On the other hand, perturbations that originate RT instabilities at the leading edge of clouds are enhanced when fields are locally stronger. The orientation of the field lines also plays an important role in the structure of filaments. Magnetic ropes are key features of systems in which fields are aligned with the wind velocity, whilst current sheets are favoured when the initial field is preferentially transverse to the wind velocity. We compare our findings with analytical predictions obtained from the linear theory of hydromagnetic stability and provide a classification of filamentary tails based on their morphology.

  3. Solar Wind Interaction and Impact on the Venus Atmosphere

    Science.gov (United States)

    Futaana, Yoshifumi; Stenberg Wieser, Gabriella; Barabash, Stas; Luhmann, Janet G.

    2017-11-01

    Venus has intrigued planetary scientists for decades because of its huge contrasts to Earth, in spite of its nickname of "Earth's Twin". Its invisible upper atmosphere and space environment are also part of the larger story of Venus and its evolution. In 60s to 70s, several missions (Venera and Mariner series) explored Venus-solar wind interaction regions. They identified the basic structure of the near-Venus space environment, for example, existence of the bow shock, magnetotail, ionosphere, as well as the lack of the intrinsic magnetic field. A huge leap in knowledge about the solar wind interaction with Venus was made possible by the 14-year long mission, Pioneer Venus Orbiter (PVO), launched in 1978. More recently, ESA's probe, Venus Express (VEX), was inserted into orbit in 2006, operated for 8 years. Owing to its different orbit from that of PVO, VEX made unique measurements in the polar and terminator regions, and probed the near-Venus tail for the first time. The near-tail hosts dynamic processes that lead to plasma energization. These processes in turn lead to the loss of ionospheric ions to space, slowly eroding the Venusian atmosphere. VEX carried an ion spectrometer with a moderate mass-separation capability and the observed ratio of the escaping hydrogen and oxygen ions in the wake indicates the stoichiometric loss of water from Venus. The structure and dynamics of the induced magnetosphere depends on the prevailing solar wind conditions. VEX studied the response of the magnetospheric system on different time scales. A plethora of waves was identified by the magnetometer on VEX; some of them were not previously observed by PVO. Proton cyclotron waves were seen far upstream of the bow shock, mirror mode waves were observed in magnetosheath and whistler mode waves, possibly generated by lightning discharges were frequently seen. VEX also encouraged renewed numerical modeling efforts, including fluid-type of models and particle-fluid hybrid type of models

  4. The interaction of katabatic winds and mountain waves

    Energy Technology Data Exchange (ETDEWEB)

    Poulos, Gregory Steve [Colorado State Univ., Fort Collins, CO (United States)

    1997-01-01

    The variation in the oft-observed, thermally-forced, nocturnal katabatic winds along the east side of the Rocky Mountains can be explained by either internal variability or interactions with various other forcings. Though generally katabatic flows have been studied as an entity protected from external forcing by strong thermal stratification, this work investigates how drainage winds along the Colorado Front Range interact with, in particular, topographically forced mountain waves. Previous work has shown, based on measurements taken during the Atmospheric Studies in Complex Terrain 1993 field program, that the actual dispersion in katabatic flows is often greater than reflected in models of dispersion. The interaction of these phenomena is complicated and non-linear since the amplitude, wavelength and vertical structure of mountain waves developed by flow over the Rocky Mountain barrier are themselves partly determined by the evolving atmospheric stability in which the drainage flows develop. Perturbations to katabatic flow by mountain waves, relative to their more steady form in quiescent conditions, are found to be caused by both turbulence and dynamic pressure effects. The effect of turbulent interaction is to create changes to katabatic now depth, katabatic flow speed, katabatic jet height and, vertical thermal stratification. The pressure effect is found to primarily influence the variability of a given katabatic now through the evolution of integrated column wave forcing on surface pressure. Variability is found to occur on two scales, on the mesoscale due to meso-gamma scale mountain wave evolution, and on the microscale, due to wave breaking. Since existing parameterizations for the statically stable case are predominantly based on nearly flat terrain atmospheric measurements under idealized or nearly quiescent conditions, it is no surprise that these parameterizations often contribute to errors in prediction, particularly in complex terrain.

  5. Interaction of turbulent length scales with wind turbine blades

    Science.gov (United States)

    Torres-Nieves, Sheilla N.

    Understanding the effects of free-stream turbulence (FST) and surface roughness on the flow around wind turbine blades is imperative in the quest for higher wind turbine efficiency, specially under stall conditions. While many investigations have focused on the aerodynamic loads on wind turbine airfoils, there are no studies that examine the effects of free-stream turbulence and surface roughness on the velocity field around a wind turbine airfoil. Hence, the aim of this investigation is to study the influence of high levels of FST on the flow around smooth and rough surfaces with pressure gradients. Moreover, of great importance in this study is the examination of how the length scales of turbulence and surface roughness interact in the flow over wind turbine airfoils to affect flow separation. Particle Image Velocimetry measurements were performed to analyze the overall flow around a S809 wind turbine blade. Results indicate that when the flow is fully attached, free-stream turbulence significantly decreases aerodynamic efficiency by 82%, yielding to higher loads and fatigue on the blades. On the contrary, when the flow is separated, the effect is reversed and aerodynamic performance is slightly improved (i.e., by 5%) by the presence of the free-stream turbulence. Analysis of the mean flow over the suction surface shows that, under stall conditions, free-stream turbulence delays separation, and surface roughness advances separation. Interestingly, the highly non-linear interaction between free-stream turbulence and surface roughness results in the further advancement of separation. Of particular interest is the study of the region closer to the wall (i.e., the boundary layer), where the flow interacts with both the surface of the blade and the free-stream. Turbulent boundary layer experiments subject to an external favorable pressure gradient (FPG) were performed to study the influence of FST, surface roughness and external pressure gradient (present around the

  6. Wind Farm Structures’ Impact on Harmonic Emission and Grid Interaction

    DEFF Research Database (Denmark)

    Kocewiak, Lukasz Hubert; Hjerrild, Jesper; Bak, Claus Leth

    The impact of a wind farm’s internal structures on harmonic emission at the point of common coupling and on the whole system frequency characteristic is investigated in this paper. The largest wind farms in the world, Horns Rev 2 Offshore Wind Farm and Polish Karnice Onshore Wind Farm......, are thoroughly analyzed. Different wind farm configurations are taken into consideration in order to entirely describe phenomena associated with harmonics. Some aspects of wind farm modelling for harmonic studies are also presented in this paper. The simulation results are compared with measurement data in order...

  7. Power Quality of Grid-Connected Wind Turbines with DFIG and Their Interaction with the Grid

    DEFF Research Database (Denmark)

    Sun, Tao

    quality issues of grid-connected wind turbines and the interaction between wind turbines and the grid. The specific goal of the research has been to investigate flicker emission and mitigation of grid-connected wind turbines with doubly fed induction generators (DFIG) during continuous operation......, and voltage recovery of such kind of grid-connected wind turbines after the clearance of a short circuit fault in the grid. As a basis of the research, a model of grid-connected wind turbines with DFIG is developed in the dedicated power system analysis tool PSCAD/EMTDC, which simulates the dynamics...... of the system from the turbine rotor, where the kinetic wind energy is converted to mechanical energy, to the grid connection point where the electric power is fed into the grid. The complete grid-connected wind turbine model includes the wind speed model, the aerodynamic model of the wind turbine...

  8. Simulation of interaction between wind farm and power system

    DEFF Research Database (Denmark)

    Sørensen, Poul Ejnar; Hansen, Anca Daniela; Janosi, L.

    2002-01-01

    A dynamic model of the wind farm Hagesholm has been implemented in the dedicated power system simulation program DIgSILENT. The wind farm con- sists of six 2MW NM2000/72 wind turbines from NEG-Micon. The model has been verified using simultaneous powerquality measurements on the 10 kV terminals...... of a single wind turbine and power performance measurements on two wind turbines. The verification shows a generally good agreement between simulations and measurements, although the simulations at higher windspeeds seem to underestimate the power and voltage fluctuations. A way to improve the simulation...

  9. Wake interaction and power production of variable height model wind farms

    DEFF Research Database (Denmark)

    Vested, Malene Hovgaard; Hamilton, N.; Sørensen, Jens Nørkær

    2014-01-01

    Understanding wake dynamics is an ongoing research topic in wind energy, since wakes have considerable effects on the power production when wind turbines are placed in a wind farm. Wind tunnel experiments have been conducted to study the wake to wake interaction in a model wind farm in tandem...... with measurements of the extracted power. The aim is to investigate how alternating mast height influences the interaction of the wakes and the power production. Via the use of stereo-particle image velocimetry, the flow field was obtained in the first and last rows of the wind turbine array as a basis...... of comparison. It was found that downstream of the exit row wind turbine, the power was increased by 25% in the case of a staggered height configuration. This is partly due to the fact that the taller turbines reach into a flow area with a softened velocity gradient. Another aspect is that the wake downstream...

  10. A survey of solar wind conditions at 5 AU: a tool for interpreting solar wind-magnetosphere interactions at Jupiter

    Energy Technology Data Exchange (ETDEWEB)

    Ebert, Robert W. [Space Science and Engineering Division, Southwest Research Institute, San Antonio, TX (United States); Bagenal, Fran [Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO (United States); McComas, David J. [Space Science and Engineering Division, Southwest Research Institute, San Antonio, TX (United States); Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX (United States); Fowler, Christopher M., E-mail: rebert@swri.edu [Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO (United States)

    2014-09-19

    We examine Ulysses solar wind and interplanetary magnetic field (IMF) observations at 5 AU for two ~13 month intervals during the rising and declining phases of solar cycle 23 and the predicted response of the Jovian magnetosphere during these times. The declining phase solar wind, composed primarily of corotating interaction regions and high-speed streams, was, on average, faster, hotter, less dense, and more Alfvénic relative to the rising phase solar wind, composed mainly of slow wind and interplanetary coronal mass ejections. Interestingly, none of solar wind and IMF distributions reported here were bimodal, a feature used to explain the bimodal distribution of bow shock and magnetopause standoff distances observed at Jupiter. Instead, many of these distributions had extended, non-Gaussian tails that resulted in large standard deviations and much larger mean over median values. The distribution of predicted Jupiter bow shock and magnetopause standoff distances during these intervals were also not bimodal, the mean/median values being larger during the declining phase by ~1–4%. These results provide data-derived solar wind and IMF boundary conditions at 5 AU for models aimed at studying solar wind-magnetosphere interactions at Jupiter and can support the science investigations of upcoming Jupiter system missions. Here, we provide expectations for Juno, which is scheduled to arrive at Jupiter in July 2016. Accounting for the long-term decline in solar wind dynamic pressure reported by McComas et al. (2013a), Jupiter's bow shock and magnetopause is expected to be at least 8–12% further from Jupiter, if these trends continue.

  11. A survey of solar wind conditions at 5 AU: A tool for interpreting solar wind-magnetosphere interactions at Jupiter

    Directory of Open Access Journals (Sweden)

    Robert Wilkes Ebert

    2014-09-01

    Full Text Available We examine Ulysses solar wind and interplanetary magnetic field (IMF observations at 5 AU for two ~13 month intervals during the rising and declining phases of solar cycle 23 and the predicted response of the Jovian magnetosphere during these times. The declining phase solar wind, composed primarily of corotating interaction regions and high-speed streams, was, on average, faster, hotter, less dense, and more Alfvénic relative to the rising phase solar wind, composed mainly of slow wind and interplanetary coronal mass ejections. Interestingly, none of solar wind and IMF distributions reported here were bimodal, a feature used to explain the bimodal distribution of bow shock and magnetopause standoff distances observed at Jupiter. Instead, many of these distributions had extended, non-Gaussian tails that resulted in large standard deviations and much larger mean over median values. The distribution of predicted Jupiter bow shock and magnetopause standoff distances during these intervals were also not bimodal, the mean/median values being larger during the declining phase by ~1 – 4%. These results provide data-derived solar wind and IMF boundary conditions at 5 AU for models aimed at studying solar wind-magnetosphere interactions at Jupiter and can support the science investigations of upcoming Jupiter system missions. Here, we provide expectations for Juno, which is scheduled to arrive at Jupiter in July 2016. Accounting for the long-term decline in solar wind dynamic pressure reported by McComas et al. (2013, Jupiter’s bow shock and magnetopause is expected to be at least 8 – 12% further from Jupiter, if these trends continue.

  12. A comparison of shock-cloud and wind-cloud interactions: the longer survival of clouds in winds

    Science.gov (United States)

    Goldsmith, K. J. A.; Pittard, J. M.

    2017-09-01

    The interaction of a hot, high-velocity wind with a cold, dense molecular cloud has often been assumed to resemble the evolution of a cloud embedded in a post-shock flow. However, no direct comparative study of these two processes currently exists in the literature. We present 2D adiabatic hydrodynamical simulations of the interaction of a Mach 10 shock with a cloud of density contrast χ = 10 and compare our results with those of a commensurate wind-cloud simulation. We then investigate the effect of varying the wind velocity, effectively altering the wind Mach number Mwind, on the cloud's evolution. We find that there are significant differences between the two processes: 1) the transmitted shock is much flatter in the shock-cloud interaction; 2) a low-pressure region in the wind-cloud case deflects the flow around the edge of the cloud in a different manner to the shock-cloud case; 3) there is far more axial compression of the cloud in the case of the shock. As Mwind increases, the normalized rate of mixing is reduced. Clouds in winds with higher Mwind also do not experience a transmitted shock through the cloud's rear and are more compressed axially. In contrast with shock-cloud simulations, the cloud mixing time normalized by the cloud-crushing time-scale tcc increases for increasing Mwind until it plateaus (at tmix ≃ 25 tcc) at high Mwind, thus demonstrating the expected Mach scaling. In addition, clouds in high Mach number winds are able to survive for long durations and are capable of being moved considerable distances.

  13. Solar wind plasma interaction with solar probe plus spacecraft

    Directory of Open Access Journals (Sweden)

    S. Guillemant

    2012-07-01

    Full Text Available 3-D PIC (Particle In Cell simulations of spacecraft-plasma interactions in the solar wind context of the Solar Probe Plus mission are presented. The SPIS software is used to simulate a simplified probe in the near-Sun environment (at a distance of 0.044 AU or 9.5 RS from the Sun surface. We begin this study with a cross comparison of SPIS with another PIC code, aiming at providing the static potential structure surrounding a spacecraft in a high photoelectron environment. This paper presents then a sensitivity study using generic SPIS capabilities, investigating the role of some physical phenomena and numerical models. It confirms that in the near- sun environment, the Solar Probe Plus spacecraft would rather be negatively charged, despite the high yield of photoemission. This negative potential is explained through the dense sheath of photoelectrons and secondary electrons both emitted with low energies (2–3 eV. Due to this low energy of emission, these particles are not ejected at an infinite distance of the spacecraft and would rather surround it. As involved densities of photoelectrons can reach 106 cm−3 (compared to ambient ions and electrons densities of about 7 × 103 cm−3, those populations affect the surrounding plasma potential generating potential barriers for low energy electrons, leading to high recollection. This charging could interfere with the low energy (up to a few tens of eV plasma sensors and particle detectors, by biasing the particle distribution functions measured by the instruments. Moreover, if the spacecraft charges to large negative potentials, the problem will be more severe as low energy electrons will not be seen at all. The importance of the modelling requirements in terms of precise prediction of spacecraft potential is also discussed.

  14. Turbulence Simulation of Laboratory Wind-Wave Interaction in High Winds and Upscaling to Ocean Conditions

    Science.gov (United States)

    2016-12-22

    mean wind profile, and a minor reduction in the form drag fraction. This supports recent theoretical perspectives that propose very differing... turnover times. For the results, wind and pressure fields are made dimensionless by (u*, u* 2 ) and all lengths are made dimensionless by  where... turnover times (~ 50) owing to the reduction in the timestep on the fine grid. We found the fine mesh runs were similar in character to the coarse mesh

  15. Wake interaction and power production of variable height model wind farms

    International Nuclear Information System (INIS)

    Vested, M H; Sørensen, J N; Hamilton, N; Cal, R B

    2014-01-01

    Understanding wake dynamics is an ongoing research topic in wind energy, since wakes have considerable effects on the power production when wind turbines are placed in a wind farm. Wind tunnel experiments have been conducted to study the wake to wake interaction in a model wind farm in tandem with measurements of the extracted power. The aim is to investigate how alternating mast height influences the interaction of the wakes and the power production. Via the use of stereo-particle image velocimetry, the flow field was obtained in the first and last rows of the wind turbine array as a basis of comparison. It was found that downstream of the exit row wind turbine, the power was increased by 25% in the case of a staggered height configuration. This is partly due to the fact that the taller turbines reach into a flow area with a softened velocity gradient. Another aspect is that the wake downstream of a tall wind turbine to some extent passes above the standard height wind turbine. Overall the experiments show that the velocity field downstream of the exit row changes considerably when the mast height is alternating

  16. Enhancement of wind energy harvesting by interaction between vortex-induced vibration and galloping

    Science.gov (United States)

    He, Xuefeng; Yang, Xiaokang; Jiang, Senlin

    2018-01-01

    Most wind energy harvesters (WEHs) that have been reported in the literature collect wind energy using only one type of wind-induced vibration, such as vortex-induced vibration (VIV), galloping, and flutter or wake galloping. In this letter, the interaction between VIV and galloping is used to improve the performance of WEHs. For a WEH constructed by attaching a bluff body with a rectangular cross-section to the free end of a piezoelectric cantilever, the measures to realize the interaction are theoretically discussed. Experiments verified the theoretical prediction that the WEHs with the same piezoelectric beam may demonstrate either separate or interactive VIV and galloping, depending on the geometries of the bluff bodies. For the WEHs with the interaction, the wind speed region of the VIV merges with that of the galloping to form a single region with high electrical outputs, which greatly increases the electrical outputs at low wind speeds. The interaction can be realized even when the predicted galloping critical speed is much higher than the predicted VIV critical speed. The proposed interaction is thus an effective approach to improve the scavenging efficiencies of WEHs operating at low wind speeds.

  17. Interaction of the interplanetary shock and tangential discontinuity in the solar wind

    Science.gov (United States)

    Goncharov, Oleksandr; Koval, Andriy; Safrankova, Jana; Nemecek, Zdenek; Prech, Lubomir; Szabo, Adam; Zastenker, Georgy N.

    2017-04-01

    Collisionless shocks play a significant role in the solar wind interaction with the Earth. Fast forward interplanetary (IP) shocks driven by coronal mass ejections or by interaction of fast and slow solar wind streams can be encountered in the interplanetary space, while the bow shock is a standing fast reverse shock formed by the interaction of the supersonic solar wind with Earth's magnetic field. Both types of shocks are responsible for a transformation of a part of the energy of the directed solar wind motion to plasma heating and to acceleration of reflected particles to high energies. It is well known that the interaction of tangential discontinuities with the bow shock can create hot flow anomalies but interactions between IP shocks and tangential discontinuities in the solar wind are studied to a lesser extent due to lack of observations. A fortunate position of many spacecraft (Wind, ACE, DSCOVR, THEMIS, Spektr-R) on June 22, 2015 allows us detailed observations of an IP shock modification due to this interaction. We present an analysis of the event supported with MHD modeling that reveals basic features of the observed IP shock ramp splitting. However, a good matching of modeling and observations was found for DSCOVR and Spektr-R located above the ecliptic plane, whereas a timing of observations below this plane demonstrates problems of modeling of highly inclined discontinuities.

  18. Winds of Massive Magnetic Stars: Interacting Fields and Flow

    Science.gov (United States)

    Daley-Yates, S.; Stevens, I. R.

    2018-01-01

    We present results of 3D numerical simulations of magnetically confined, radiatively driven stellar winds of massive stars, conducted using the astrophysical MHD code Pluto, with a focus on understanding the rotational variability of radio and sub-mm emission. Radiative driving is implemented according to the Castor, Abbott and Klein theory of radiatively driven winds. Many magnetic massive stars posses a magnetic axis which is inclined with respect to the rotational axis. This misalignment leads to a complex wind structure as magnetic confinement, centrifugal acceleration and radiative driving act to channel the circumstellar plasma into a warped disk whose observable properties should be apparent in multiple wavelengths. This structure is analysed to calculate free-free thermal radio emission and determine the characteristic intensity maps and radio light curves.

  19. Interaction of Accretion Shocks with Winds Kinsuk Acharya , Sandip ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Abstract. Accretion shocks are known to oscillate in presence of cool- ing processes in the disk. This oscillation may also cause quasi-periodic oscillations of black holes. In the presence of strong winds, these shocks have oscillations in vertical direction as well. We show examples of shock oscillations under the influence of ...

  20. Interacting Winds in Eclipsing Symbiotic Systems–The Case Study ...

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... We report the mathematical representation of the so called eccentric eclipse model, whose numerical solutions can be used to obtain the physical parameters of a quiescent eclipsing symbiotic system. Indeed the nebular region produced by the collision of the stellar winds should be shifted to the orbital ...

  1. Wind turbine wake interactions; results from blind tests

    Science.gov (United States)

    Krogstad, Per-Åge; Sætran, Lars

    2015-06-01

    Results from three "Blind test" Workshops on wind turbine wake modeling are presented. While the first "Blind test" (BT1, 2011) consisted of a single model turbine located in a large wind tunnel, the complexity was increased for each new test in order to see how various models performed. Thus the next "Blind test" (BT2, 2012) had two turbines mounted in-line. This is a crucial test for models intended to predict turbine performances in a wind farm. In the last "Blind test" (BT3, 2013) the two turbines were again mounted in-line, but offset sideways so that the rotor of the downstream turbine only intersected half the wake from the upstream turbine. This case produces high dynamic loads and strong asymmetry in the wake. For each "Blind test" the turbine geometry and wind tunnel environment was specified and the participants were asked to predict the turbine performances, as well as the wake development to five diameters downstream of the second turbine. For the first two tests axisymmetry could be assumed if the influence of the towers was neglected. This was not possible in BT3 and therefore only fully 3D methods could be applied. In all tests the prediction scatter was surprisingly high.

  2. Power Properties of Two Interacting Wind Turbine Rotors

    DEFF Research Database (Denmark)

    Okulov, Valery; Mikkelsen, Robert Flemming; Sørensen, Jens Nørkær

    2016-01-01

    In the current experiments, two identical wind turbine models were placed in uniform flow conditions in a water flume. The initial flow in the flume was subject to a very low turbulence level, limiting the influence of external disturbances on the development of the inherent wake instability. Bot...

  3. Nearshore regional behavior of lightning interaction with wind turbines

    Directory of Open Access Journals (Sweden)

    Gilbert A. Malinga

    2016-01-01

    Full Text Available The severity of lightning strikes on offshore wind turbines built along coastal and nearshore regions can pose safety concerns that are often overlooked. In this research study the behavior of electrical discharges for wind turbines that might be located in the nearshore regions along the East Coast of China and Sea of Japan were characterized using a physics-based model that accounted for a total of eleven different geometrical and lightning parameters. Utilizing the electrical potential field predicted using this model it was then possible to estimate the frequency of lightning strikes and the distribution of electrical loads utilizing established semi-empirical relationships and available data. The total number of annual lightning strikes on an offshore wind turbine was found to vary with hub elevation, extent of cloud cover, season and geographical location. The annual lightning strike rate on a wind turbine along the nearshore region on the Sea of Japan during the winter season was shown to be moderately larger compared to the lightning strike frequency on a turbine structure on the East Coast of China. Short duration electrical discharges, represented using marginal probability functions, were found to vary with season and geographical location, exhibiting trends consistent with the distribution of the electrical peak current. It was demonstrated that electrical discharges of moderately long duration typically occur in the winter months on the East Coast of China and the summer season along the Sea of Japan. In contrast, severe electrical discharges are typical of summer thunderstorms on the East Coast of China and winter frontal storm systems along the West Coast of Japan. The electrical charge and specific energy dissipated during lightning discharges on an offshore wind turbine was found to vary stochastically, with severe electrical discharges corresponding to large electrical currents of long duration.

  4. Harmonic Propagation and Interaction Evaluation between Small-Scale Wind Farms and Nonlinear Loads

    Directory of Open Access Journals (Sweden)

    Cheng-Xiong Mao

    2013-07-01

    Full Text Available Distributed generation is a flexible and effective way to utilize renewable energy. The dispersed generators are quite close to the load, and pose some power quality problems such as harmonic current emissions. This paper focuses on the harmonic propagation and interaction between a small-scale wind farm and nonlinear loads in the distribution grid. Firstly, by setting the wind turbines as P – Q(V nodes, the paper discusses the expanding Newton-Raphson power flow method for the wind farm. Then the generalized gamma mixture models are proposed to study the non-characteristic harmonic propagation of the wind farm, which are based on Gaussian mixture models, improved phasor clustering and generalized Gamma models. After the integration of the small-scale wind farm, harmonic emissions of nonlinear loads will become random and fluctuating due to the non-stationary wind power. Furthermore, in this paper the harmonic coupled admittance matrix model of nonlinear loads combined with a wind farm is deduced by rigorous formulas. Then the harmonic propagation and interaction between a real wind farm and nonlinear loads are analyzed by the harmonic coupled admittance matrix and generalized gamma mixture models. Finally, the proposed models and methods are verified through the corresponding simulation models in MATLAB/SIMULINK and PSCAD/EMTDC.

  5. Aerodynamic Interactions between Pairs of Vertical-Axis Wind Turbines

    Science.gov (United States)

    Brownstein, Ian; Dabiri, John

    2017-11-01

    Increased power production has been observed in downstream vertical-axis wind turbines (VAWTs) when positioned offset from the wake of upstream turbines. This effect was found to exist in both laboratory and field environments with pairs of co- and counter-rotating turbines. It is hypothesized that the observed power production enhancement is due to flow acceleration adjacent to the upstream turbine caused by bluff body blockage, which increases the incident freestream velocity on appropriately positioned downstream turbines. This type of flow acceleration has been observed in computational and laboratory studies of VAWTs and will be further investigated here using 3D-PTV measurements around pairs of laboratory-scale VAWTs. These measurements will be used to understand the mechanisms behind the performance enhancement effect and seek to determine optimal separation distances and angles between turbines based on turbine design parameters. These results will lead to recommendations for optimizing the power production of VAWT wind farms which utilize this effect.

  6. Waste-Management Education and Research Consortium (WERC) annual progress report, 1991--1992. Appendixes

    Energy Technology Data Exchange (ETDEWEB)

    1992-04-07

    This report contains the following appendices: Appendix A - Requirements for Undergraduate Level; Appendix B - Requirements for Graduate Level; Appendix C - Graduate Degree In Environmental Engineering; Appendix D - Non-degree Certificate Program; Appendix E - Curriculum for Associate Degree Program; Appendix F - Curriculum for NCC Program; Appendix G - Information 1991 Teleconference Series; Appendix H - Information on 1992 Teleconference Series; Appendix I - WERC interactive Television Courses; Appendix J - WERC Research Seminar Series; Appendix K - Sites for Hazardous/Radioactive Waste Management Series; Appendix L- Summary of Technology Development of the Second Year; Appendix M - List of Major Publications Resulting from WERC; Appendix N - Types of Equipment at WERC Laboratories.

  7. Early time interaction of lithium ions with the solar wind in the AMPTE mission

    International Nuclear Information System (INIS)

    Lui, A.T.Y.; Goodrich, C.C.; Mankofsky, A.; Papadopoulos, K.

    1986-01-01

    The early time interaction of an artificially injected lithium cloud with the solar wind is simulated with a one-dimensional hybrid code. Simulation results indicate that the lithium cloud presents an obstacle to the solar wind flow, forming a shock-like interaction region. Several notable features are found: (1) The magnetic field is enhanced up to a factor of about 6 followed by a magnetic cavity downstream. (2) Solar wind ions are slowed down inside the lithium cloud, with substantial upstream reflection. (3) Most of the lithium ions gradually pick up the velocity of the solar wind and move downstream. (4) Intense and short-wavelength electric fields exist ahead of the interaction region. (5) Strong electron heating occurs within the lithium clouds. (6) The convection electric field in the in the solar wind is modulated in the interaction region. The simulation results are in remarkable agreement with in situ spacecraft measurements made during lithium releases in the solar wind by the AMPTE (Active magnetospheric Particle Tracer Explorers) Program

  8. Magnetic fields in the solar system planets, moons and solar wind interactions

    CERN Document Server

    Wicht, Johannes; Gilder, Stuart; Holschneider, Matthias

    2018-01-01

    This book addresses and reviews many of the still little understood questions related to the processes underlying planetary magnetic fields and their interaction with the solar wind. With focus on research carried out within the German Priority Program ”PlanetMag”, it also provides an overview of the most recent research in the field. Magnetic fields play an important role in making a planet habitable by protecting the environment from the solar wind. Without the geomagnetic field, for example, life on Earth as we know it would not be possible. And results from recent space missions to Mars and Venus strongly indicate that planetary magnetic fields play a vital role in preventing atmospheric erosion by the solar wind. However, very little is known about the underlying interaction between the solar wind and a planet’s magnetic field. The book takes a synergistic interdisciplinary approach that combines newly developed tools for data acquisition and analysis, computer simulations of planetary interiors an...

  9. The importance of including dynamic soil-structure interaction into wind turbine simulation codes

    DEFF Research Database (Denmark)

    Damgaard, Mads; Andersen, Lars Vabbersgaard; Ibsen, Lars Bo

    2014-01-01

    is examined. The optimal order of the models is determined and implemented into the aeroelastic code HAWC2, where the dynamic response of a 5.0 MW wind turbine is evaluated. In contrast to the fore-aft vibrations, the inclusion of soil-structure interaction is shown to be critical for the side-side vibrations......A rigorous numerical model, describing a wind turbine structure and subsoil, may contain thousands of degrees of freedom, making the approach computationally inefficient for fast time domain analysis. In order to meet the requirements of real-time calculations, the dynamic impedance...... of the wind turbine structure....

  10. Sub-Synchronous Interaction Analysis between DFIG Based Wind Farm and Series Compensated Network

    OpenAIRE

    Wang, Yun; Wu, Qiuwei; Kang, Shaoli

    2016-01-01

    This paper analyzes the sub-synchronous interaction (SSI) phenomenon between the doubly fed induction generator (DFIG) based wind farm (WF) and the series capacitor compensated network. The possible types of SSI in the DFIG based WF are studied. The factors influencing the SSI of DFIG based WF are investigated. The large signal stability and small signal stability of the DFIG based WF with different series compensation (SC) level and wind speed are simulated and compared.

  11. Sub-Synchronous Interaction Analysis between DFIG Based Wind Farm and Series Compensated Network

    DEFF Research Database (Denmark)

    Wang, Yun; Wu, Qiuwei; Kang, Shaoli

    2016-01-01

    This paper analyzes the sub-synchronous interaction (SSI) phenomenon between the doubly fed induction generator (DFIG) based wind farm (WF) and the series capacitor compensated network. The possible types of SSI in the DFIG based WF are studied. The factors influencing the SSI of DFIG based WF...... are investigated. The large signal stability and small signal stability of the DFIG based WF with different series compensation (SC) level and wind speed are simulated and compared....

  12. Three Dimensional Explicit Model for Cometary Tail Ions Interactions with Solar Wind

    Science.gov (United States)

    Al Bermani, M. J. F.; Alhamed, S. A.; Khalaf, S. Z.; Ali, H. Sh.; Selman, A. A.

    2009-06-01

    The different interactions between cometary tail and solar wind ions are studied in the present paper based on three-dimensional Lax explicit method. The model used in this research is based on the continuity equations describing the cometary tail-solar wind interactions. Three dimensional system was considered in this paper. Simulation of the physical system was achieved using computer code written using Matlab 7.0. The parameters studied here assumed Halley comet type and include the particle density rho, the particles velocity v, the magnetic field strength B, dynamic pressure p and internal energy E. The results of the present research showed that the interaction near the cometary nucleus is mainly affected by the new ions added to the plasma of the solar wind, which increases the average molecular weight and result in many unique characteristics of the cometary tail. These characteristics were explained in the presence of the IMF.

  13. Effect of soil-foundation-structure interaction on the seismic response of wind turbines

    Directory of Open Access Journals (Sweden)

    Sam Austin

    2017-09-01

    Full Text Available Soil-foundation-structure interaction can affect the seismic response of wind turbines. This paper studies the effects of soil-foundation-structure interaction on the seismic response of 65 kW, 1 MW, and 2 MW horizontal-axis wind turbines with truncated cone steel towers. Four types of foundations with frequency-based design were analyzed, including spread foundation, mono pile, pile group with cap, and anchored spread foundation. Soil is modeled both implicitly (subgrade reaction modulus and explicitly. The finite element model developed using the ANSYS program was first validated using experimental data. Numerical models are then analyzed in both frequency and time domains using the Block Lanczos and generalized HHT-α formulations. Recommendations were given to simplify the soil-foundation-structure interaction analysis of wind turbines subjected to seismic loading.

  14. Study of hydrocarbon-shale interaction. Progress report No. 10. Part III. Appendix B

    Energy Technology Data Exchange (ETDEWEB)

    1978-01-01

    The volume represents a continuation of Appendix B in which data are presented on diffusion, degassing, isotherm, and BET parameters of particulate core samples from gas wells in Ohio, West Virginia, Illinois, and Kentucky. (JRD)

  15. Oscillation mode analysis considering the interaction between a DFIG-based wind turbine and the grid

    Science.gov (United States)

    Wu, Wangping; Xie, Da; Lu, Yupu; Zhao, Zuyi; Yu, Songtao

    2017-01-01

    Sub-synchronous interactions between wind farms and transmission networks with series compensation have drawn great attention. As most large wind farms in Europe and Asia employ doubly fed induction generator turbines, there has recently been a growing interest in studying this phenomenon. To study the stability of wind turbine with doubly fed induction generator after a small disturbance, a complete small signal system is built in this paper. By using eigenvalue and participation factor analysis, the relation between the modes and state variables can be discovered. Thereafter, the oscillation modes are classified into electrical resonance, sub-synchronous resonance, sub-synchronous oscillation, sub-synchronous control interaction, and low frequency oscillation. To verify the oscillation frequency of each oscillation mode, time-domain simulation based on MATLAB/Simulink is presented. The simulation results justify the effectiveness of the small-signal models.

  16. Numerical investigation of the wake interaction between two model wind turbines with span-wise offset

    DEFF Research Database (Denmark)

    Sarmast, Sasan; Chivaee, Hamid Sarlak; Ivanell, Stefan

    2014-01-01

    Wake interaction between two model scale wind turbines with span-wise offset is investigated numerically using Large Eddy Simulation (LES) and the results are validated against the experimental data. An actuator line technique is used for modeling the rotor. The investigated setup refers...... to a series of experimental measurements of two model scale turbines conducted by NTNU in low speed wind tunnel in which the two wind turbines are aligned with a span-wise offset resulting in half wake interaction. Two levels of free-stream turbulence are tested, the minimum undisturbed level of about Ti ≈ 0.......23% and a high level of about Ti ≈ 10% using a passive upstream grid. The results show that the rotor characteristics for both rotors are well captured numerically even if the downstream rotor operates into stall regimes. There are however some difficulties in correct prediction of the thrust level...

  17. Importance of air-sea interaction on wind waves, storm surge and hurricane simulations

    Science.gov (United States)

    Chen, Yingjian; Yu, Xiping

    2017-04-01

    It was reported from field observations that wind stress coefficient levels off and even decreases when the wind speed exceeds 30-40 m/s. We propose a wave boundary layer model (WBLM) based on the momentum and energy conservation equations. Taking into account the physical details of the air-sea interaction process as well as the energy dissipation due to the presence of sea spray, this model successfully predicts the decreasing tendency of wind stress coefficient. Then WBLM is embedded in the current-wave coupled model FVCOM-SWAVE to simulate surface waves and storm surge under the forcing of hurricane Katrina. Numerical results based on WBLM agree well with the observed data of NDBC buoys and tide gauges. Sensitivity analysis of different wind stress evaluation methods also shows that large anomalies of significant wave height and surge elevation are captured along the passage of hurricane core. The differences of the local wave height are up to 13 m, which is in accordance with the general knowledge that the ocean dynamic processes under storm conditions are very sensitive to the amount of momentum exchange at the air-sea interface. In the final part of the research, the reduced wind stress coefficient is tested in the numerical forecast of hurricane Katrina. A parabolic formula fitted to WBLM is employed in the atmosphere-ocean coupled model COAWST. Considering the joint effects of ocean cooling and reduced wind drag, the intensity metrics - the minimum sea level pressure and the maximum 10 m wind speed - are in good inconsistency with the best track result. Those methods, which predict the wind stress coefficient that increase or saturate in extreme wind condition, underestimate the hurricane intensity. As a whole, we unify the evaluation methods of wind stress in different numerical models and yield reasonable results. Although it is too early to conclude that WBLM is totally applicable or the drag coefficient does decrease for high wind speed, our current

  18. WINDS, CLUMPS, AND INTERACTING COSMIC RAYS IN M82

    Energy Technology Data Exchange (ETDEWEB)

    Yoast-Hull, Tova M.; Everett, John E.; Zweibel, Ellen G. [Department of Physics, University of Wisconsin-Madison, WI (United States); Gallagher, J. S. III, E-mail: yoasthull@wisc.edu [Department of Astronomy, University of Wisconsin-Madison, WI (United States)

    2013-05-01

    We construct a family of models for the evolution of energetic particles in the starburst galaxy M82 and compare them to observations to test the calorimeter assumption that all cosmic ray energy is radiated in the starburst region. Assuming constant cosmic ray acceleration efficiency with Milky Way parameters, we calculate the cosmic-ray proton and primary and secondary electron/positron populations as a function of energy. Cosmic rays are injected with Galactic energy distributions and electron-to-proton ratio via Type II supernovae at the observed rate of 0.07 yr{sup -1}. From the cosmic ray spectra, we predict the radio synchrotron and {gamma}-ray spectra. To more accurately model the radio spectrum, we incorporate a multiphase interstellar medium in the starburst region of M82. Our model interstellar medium is highly fragmented with compact dense molecular clouds and dense photoionized gas, both embedded in a hot, low density medium in overall pressure equilibrium. The spectra predicted by this one-zone model are compared to the observed radio and {gamma}-ray spectra of M82. {chi}{sup 2} tests are used with radio and {gamma}-ray observations and a range of model predictions to find the best-fit parameters. The best-fit model yields constraints on key parameters in the starburst zone of M82, including a magnetic field strength of {approx}250 {mu}G and a wind advection speed in the range of 300-700 km s{sup -1}. We find that M82 is a good electron calorimeter but not an ideal cosmic-ray proton calorimeter and discuss the implications of our results for the astrophysics of the far-infrared-radio correlation in starburst galaxies.

  19. H∞ Current Damping Control of DFIG based Wind Farm for Sub-Synchronous Control Interaction Mitigation

    DEFF Research Database (Denmark)

    Wang, Yun; Wu, Qiuwei; Yang, Rong

    2018-01-01

    This paper proposes an H∞ damping controller for the doubly-fed induction generator (DFIG) based wind farm (WF) to mitigate sub-synchronous control interactions (SSCI) with series capacitor compensated lines. A multi-input multi-output (MIMO) uncertain state-space model is developed to reflect...

  20. Predicting wind farm wake interaction with RANS: an investigation of the Coriolis force

    DEFF Research Database (Denmark)

    van der Laan, Paul; Hansen, Kurt Schaldemose; Sørensen, Niels N.

    2015-01-01

    A Reynolds-averaged Navier-Stokes code is used to simulate the interaction of two neighboring wind farms. The influence of the Coriolis force is investigated by modeling the atmospheric surface/boundary layer with three different methodologies. The results show that the Coriolis force is negligible...

  1. Hourly interaction between wind speed and energy fluxes in Brazilian Wetlands - Mato Grosso - Brazil.

    Science.gov (United States)

    Rodrigues, Thiago R; Curado, Leone F A; Pereira, Vinicius M R; Sanches, Luciana; Nogueira, José S

    2016-01-01

    Matter and energy flux dynamics of wetlands are important to understand environmental processes that govern biosphere-atmosphere interactions across ecosystems. This study presents analyses about hourly interaction between wind speed and energy fluxes in Brazilian Wetlands - Mato Grosso - Brazil. This study was conducted in Private Reserve of Natural Heritage (PRNH SESC, 16º39'50''S; 56º47'50''W) in Brazilian Wetland. According to Curado et al. (2012), the wet season occurs between the months of January and April, while the June to September time period is the dry season. Results presented same patterns in energies fluxes in all period studied. Wind speed and air temperature presented same patterns, while LE was relative humidity presented inverse patterns of the air temperature. LE was predominant in all seasons and the sum of LE and H was above 90% of net radiation. Analyses of linear regression presented positive interactions between wind speed and LE, and wind speed and H in all seasons, except in dry season of 2010. Confidence coefficient regression analyses present statistical significance in all wet and dry seasons, except dry season of 2010, suggest that LE and H had interaction with other micrometeorological variables.

  2. Hourly interaction between wind speed and energy fluxes in Brazilian Wetlands - Mato Grosso - Brazil

    Directory of Open Access Journals (Sweden)

    THIAGO R. RODRIGUES

    Full Text Available ABSTRACT Matter and energy flux dynamics of wetlands are important to understand environmental processes that govern biosphere-atmosphere interactions across ecosystems. This study presents analyses about hourly interaction between wind speed and energy fluxes in Brazilian Wetlands - Mato Grosso - Brazil. This study was conducted in Private Reserve of Natural Heritage (PRNH SESC, 16º39'50''S; 56º47'50''W in Brazilian Wetland. According to Curado et al. (2012, the wet season occurs between the months of January and April, while the June to September time period is the dry season. Results presented same patterns in energies fluxes in all period studied. Wind speed and air temperature presented same patterns, while LE was relative humidity presented inverse patterns of the air temperature. LE was predominant in all seasons and the sum of LE and H was above 90% of net radiation. Analyses of linear regression presented positive interactions between wind speed and LE, and wind speed and H in all seasons, except in dry season of 2010. Confidence coefficient regression analyses present statistical significance in all wet and dry seasons, except dry season of 2010, suggest that LE and H had interaction with other micrometeorological variables.

  3. Climate change amplifies the interactions between wind and bark beetle disturbances in forest landscapes.

    Science.gov (United States)

    Seidl, Rupert; Rammer, Werner

    2017-07-01

    Growing evidence suggests that climate change could substantially alter forest disturbances. Interactions between individual disturbance agents are a major component of disturbance regimes, yet how interactions contribute to their climate sensitivity remains largely unknown. Here, our aim was to assess the climate sensitivity of disturbance interactions, focusing on wind and bark beetle disturbances. We developed a process-based model of bark beetle disturbance, integrated into the dynamic forest landscape model iLand (already including a detailed model of wind disturbance). We evaluated the integrated model against observations from three wind events and a subsequent bark beetle outbreak, affecting 530.2 ha (3.8 %) of a mountain forest landscape in Austria between 2007 and 2014. Subsequently, we conducted a factorial experiment determining the effect of changes in climate variables on the area disturbed by wind and bark beetles separately and in combination. iLand was well able to reproduce observations with regard to area, temporal sequence, and spatial pattern of disturbance. The observed disturbance dynamics was strongly driven by interactions, with 64.3 % of the area disturbed attributed to interaction effects. A +4 °C warming increased the disturbed area by +264.7 % and the area-weighted mean patch size by +1794.3 %. Interactions were found to have a ten times higher sensitivity to temperature changes than main effects, considerably amplifying the climate sensitivity of the disturbance regime. Disturbance interactions are a key component of the forest disturbance regime. Neglecting interaction effects can lead to a substantial underestimation of the climate change sensitivity of disturbance regimes.

  4. Soil structure interaction in offshore wind turbine collisions

    DEFF Research Database (Denmark)

    Samsonovs, Artjoms; Giuliani, Luisa; Zania, Varvara

    2014-01-01

    after a ship collision, thus providing an insight on the consequences of a collision event and on the main aspects to be considered when designing for this load case. In particular, the role of the foundation soil properties (site conditions) on the response of the structural system is investigated....... Dynamic finite element analyses have been performed taking into account the geometric and material nonlinearity of the tower, and the effects of soil structure interaction (SSI) have been studied in two representative collision scenarios of a service vessel with the turbine: a moderate energy impact...

  5. 14 CFR Appendix G to Part 135 - Extended Operations (ETOPS)

    Science.gov (United States)

    2010-01-01

    ... this appendix, (after completing the wind calculation in G135.2.7(a)(2) of this appendix), the... anticipation of possible icing during the diversion: (i) Fuel that would be burned as a result of airframe... completing the wind calculation in paragraph G135.2.7(a)(2) of this appendix), the certificate holder must...

  6. Comet 73P Measurements of Solar Wind Interactions, Cometary Ion Pickup, and Spatial Distribution

    Science.gov (United States)

    Gilbert, J. A.; Lepri, S. T.; Rubin, M.; Combi, M. R.; Zurbuchen, T.

    2015-12-01

    Several fragments of Comet 73P/Schwassmann-Wachmann 3 passed near the Earth following a 2006 disintegration episode. Unique measurements regarding the charge state composition and the elemental abundances of both cometary and heliospheric plasma were made during this time by both the ACE/SWICS and Wind/STICS sensors. As the solar wind passed through the neutral cometary coma, it experienced charge exchange that was observed as an increase in the ratio of He+/He++. In addition, particles originating from fragments trailing the major cometary objects were ionized and picked up by the solar wind. The cometary material can be identified by the concentrations of water-group pickup ions having a mass-per-charge ratio of 16-18 amu/e, indicating that these are actively sublimating fragments. Here we present an analysis of cometary composition, spatial distribution, directionality, and heliospheric interactions with a focus on Helium, Carbon (C/O), and water-group ions.

  7. Modeling Solar Wind Expansion with Wave-Particle Interactions and Coulomb Collisions

    Science.gov (United States)

    Matteini, L.; Hellinger, P.; Landi, S.; Pantellini, F. G. E.; Velli, M.; Franci, L.; Verdini, A.

    2017-12-01

    The evolution of the solar wind plasma is strongly influenced by its spherical expansion in interplanetary space. Due to the weak - but not fully negligible - collisionality of the plasma, the behaviour of the system can be hardly modelled through standard approaches, either fluid or fully collisionless. Moreover, solar wind microphysics depends on many different processes, including the interaction of particles with background waves and turbulence, and plasma instabilities. Disentangling the effect of these processes from the role of intra- and inter-species particle collisions in the framework of the overall secular evolution imposed by the expansion is particularly challenging.In this presentation we will review some basics of the solar wind expansion as well as some of the recent results obtained by means of kinetic numerical models which take into account the radial expansion on the plasma, with emphasis on the comparison with in situ observations and the role of the forthcoming Solar Orbiter and Parker Solar Probe missions.

  8. Wide Field-of-View Soft X-Ray Imaging for Solar Wind-Magnetosphere Interactions

    Science.gov (United States)

    Walsh, B. M.; Collier, M. R.; Kuntz, K. D.; Porter, F. S.; Sibeck, D. G.; Snowden, S. L.; Carter, J. A.; Collado-Vega, Y.; Connor, H. K.; Cravens, T. E.; hide

    2016-01-01

    Soft X-ray imagers can be used to study the mesoscale and macroscale density structures that occur whenever and wherever the solar wind encounters neutral atoms at comets, the Moon, and both magnetized and unmagnetized planets. Charge exchange between high charge state solar wind ions and exospheric neutrals results in the isotropic emission of soft X-ray photons with energies from 0.1 to 2.0 keV. At Earth, this process occurs primarily within the magnetosheath and cusps. Through providing a global view, wide field-of-view imaging can determine the significance of the various proposed solar wind-magnetosphere interaction mechanisms by evaluating their global extent and occurrence patterns. A summary of wide field-of-view (several to tens of degrees) soft X-ray imaging is provided including slumped micropore microchannel reflectors, simulated images, and recent flight results.

  9. Solar-wind interactions with the moon - Nature and composition of nitrogen compounds

    Science.gov (United States)

    Mukherjee, N. R.

    1981-01-01

    The direct interaction of the solar wind with the lunar surface results in a complete absorption of the solar wind corpuscles by the lunar surface material, with no upstream bow-shock but a cavity downstream from the lunar body. The active N ions and atoms derived from the solar wind were considered in the calculation of the radicals and compounds of nitrogen in the lunar material atmosphere, where the main species escaping from the surface to the atmosphere are NO and NH3 with near-surface concentrations of 327 and 295/cu cm, respectively. While the calculated concentration of NH3 seems consistent with the sunrise concentration results of the mass spectrometer implanted on the lunar surface, there has been no report of NO detection.

  10. Wind Structure and Wind Loading

    DEFF Research Database (Denmark)

    Brorsen, Michael

    The purpose of this note is to provide a short description of wind, i.e. of the flow in the atmosphere of the Earth and the loading caused by wind on structures. The description comprises: causes to the generation of windhe interaction between wind and the surface of the Earthhe stochastic nature...... of windhe interaction between wind and structures, where it is shown that wind loading depends strongly on this interaction...

  11. Hybrid Simulations of the Interaction Between Solar Wind Flow and the Hermean Magnetosphere

    Science.gov (United States)

    Travnicek, P.; Hellinger, P.; Schriver, D.; Ashour-Abdalla, M.

    2003-12-01

    We examine the magnetosphere of Mercury using global three dimensional hybrid plasma simulations. Hybrid simulations treat ions as particles and electrons as a fluid. Having ions as particles allows ion kinetic behavior and waves to be included in the physical treatment of the plasma as compared to magnetohydrodynamic (MHD) modeling that treats the plasma as a single magnetized fluid and does not include such kinetic effects. Kinetic effects are essential for understanding magnetospheric physics. Hybrid simulations scale to the ion inertial length and thus on a global scale are somewhat limited in spatial extent compared to an MHD simulation. We note effects caused by the scalling of the numerical model of the magnetized obstacle interacting with the solar wind flow with the full scale simulation. Hermean magnetosphere is estimated to be only a few times the planetary radius, it can fit within a hybrid simulation system. The overal structure of the interaction between a magnetized obstacle in the solar wind flow is determined by few basic parameters (namely the solar wind density, background magnetic field, and the speed of solar wind, and also the strength of the magnetic dipole of the obstacle and its radius). The structure of the interaction of the solar wind flow with Mercury is to a large extend unique when compared to other planets. For example, the magnetic moment of the Mercury is over 1000 times smaller than that of the Earth and also the solar wind is stronger nearby Mercury than at Earth's vicinity. The typical magnetosperic scales are comparable to the ion gyroradii and hence kinetic effects are important for the overall structure of the interaction between the Hermean magnetospere and the solar wind. In this paper we shall focus on the study of the overal structure of the bow shock and magnetosheath of Mercury. We shall examine the formation of the magnetospheric tail. We shall study particle distribution functions in different locations of the

  12. Flexible interaction of plug-in electric vehicle parking lots for efficient wind integration

    International Nuclear Information System (INIS)

    Heydarian-Forushani, E.; Golshan, M.E.H.; Shafie-khah, M.

    2016-01-01

    Highlights: • Interactive incorporation of plug-in electric vehicle parking lots is investigated. • Flexible energy and reserve services are provided by electric vehicle parking lots. • Uncertain characterization of electric vehicle owners’ behavior is taken into account. • Coordinated operation of parking lots can facilitate wind power integration. - Abstract: The increasing share of uncertain wind generation has changed traditional operation scheduling of power systems. The challenges of this additional variability raise the need for an operational flexibility in providing both energy and reserve. One key solution is an effective incorporation of plug-in electric vehicles (PEVs) into the power system operation process. To this end, this paper proposes a two-stage stochastic programming market-clearing model considering the network constraints to achieve the optimal scheduling of conventional units as well as PEV parking lots (PLs) in providing both energy and reserve services. Different from existing works, the paper pays more attention to the uncertain characterization of PLs takes into account the arrival/departure time of PEVs to/from the PL, the initial state of charge (SOC) of PEVs, and their battery capacity through a set of scenarios in addition to wind generation scenarios. The results reveal that although the cost saving as a consequence of incorporating PL to the grid is below 1% of total system cost, however, flexible interactions of PL in the energy and reserve markets can promote the integration of wind power more than 13.5%.

  13. Role of subgrid-scale modeling in large eddy simulation of wind turbine wake interactions

    DEFF Research Database (Denmark)

    Sarlak, Hamid; Meneveau, C.; Sørensen, Jens Nørkær

    2015-01-01

    A series of simulations are carried out to evaluate specific features of the Large Eddy Simulation (LES) technique in wind turbine wake interactions. We aim to model wake interactions of two aligned model rotors. The effects of the rotor resolution, actuator line force filter size, and Reynolds...... number are investigated at certain tip speed ratios. The numerical results are validated against wind tunnel measurements in terms of the mean velocity, turbulence intensity and the power and thrust coefficients. Special emphasis is placed on the role played by subgrid scale (SGS) models in affecting...... the flow structures and turbine loading, as this has been studied less in prior investigations. It is found that, compared with the effects of rotor resolution and force kernel size, the SGS models have only a minor impact on the wake and predicted power performance. These observations confirm the usual...

  14. Modelling the solar wind interaction with Mercury by a quasi-neutral hybrid model

    Directory of Open Access Journals (Sweden)

    E. Kallio

    2003-11-01

    Full Text Available Quasi-neutral hybrid model is a self-consistent modelling approach that includes positively charged particles and an electron fluid. The approach has received an increasing interest in space plasma physics research because it makes it possible to study several plasma physical processes that are difficult or impossible to model by self-consistent fluid models, such as the effects associated with the ions’ finite gyroradius, the velocity difference between different ion species, or the non-Maxwellian velocity distribution function. By now quasi-neutral hybrid models have been used to study the solar wind interaction with the non-magnetised Solar System bodies of Mars, Venus, Titan and comets. Localized, two-dimensional hybrid model runs have also been made to study terrestrial dayside magnetosheath. However, the Hermean plasma environment has not yet been analysed by a global quasi-neutral hybrid model. In this paper we present a new quasi-neutral hybrid model developed to study various processes associated with the Mercury-solar wind interaction. Emphasis is placed on addressing advantages and disadvantages of the approach to study different plasma physical processes near the planet. The basic assumptions of the approach and the algorithms used in the new model are thoroughly presented. Finally, some of the first three-dimensional hybrid model runs made for Mercury are presented. The resulting macroscopic plasma parameters and the morphology of the magnetic field demonstrate the applicability of the new approach to study the Mercury-solar wind interaction globally. In addition, the real advantage of the kinetic hybrid model approach is to study the property of individual ions, and the study clearly demonstrates the large potential of the approach to address these more detailed issues by a quasi-neutral hybrid model in the future.Key words. Magnetospheric physics (planetary magnetospheres; solar wind-magnetosphere interactions – Space plasma

  15. Modelling accretion disc and stellar wind interactions: the case of Sgr A.

    Science.gov (United States)

    Christie, I M; Petropoulou, M; Mimica, P; Giannios, D

    2016-07-01

    Sgr A* is an ideal target to study low-luminosity accreting systems. It has been recently proposed that properties of the accretion flow around Sgr A* can be probed through its interactions with the stellar wind of nearby massive stars belonging to the S-cluster. When a star intercepts the accretion disc, the ram and thermal pressures of the disc terminate the stellar wind leading to the formation of a bow shock structure. Here, a semi-analytical model is constructed which describes the geometry of the termination shock formed in the wind. With the employment of numerical hydrodynamic simulations, this model is both verified and extended to a region prone to Kelvin-Helmholtz instabilities. Because the characteristic wind and stellar velocities are in ∼10 8  cm s -1 range, the shocked wind may produce detectable X-rays via thermal bremsstrahlung emission. The application of this model to the pericentre passage of S2, the brightest member of the S-cluster, shows that the shocked wind produces roughly a month long X-ray flare with a peak luminosity of L ≈ 4 × 10 33  erg s -1 for a stellar mass-loss rate, disc number density, and thermal pressure strength of [Formula: see text], n d  = 10 5  cm -3 , and α = 0.1, respectively. This peak luminosity is comparable to the quiescent X-ray emission detected from Sgr A* and is within the detection capabilities of current X-ray observatories. Its detection could constrain the density and thickness of the disc at a distance of ∼3000 gravitational radii from the supermassive black hole.

  16. Filament formation in wind-cloud interactions- II. Clouds with turbulent density, velocity, and magnetic fields

    Science.gov (United States)

    Banda-Barragán, W. E.; Federrath, C.; Crocker, R. M.; Bicknell, G. V.

    2018-01-01

    We present a set of numerical experiments designed to systematically investigate how turbulence and magnetic fields influence the morphology, energetics, and dynamics of filaments produced in wind-cloud interactions. We cover 3D, magnetohydrodynamic systems of supersonic winds impacting clouds with turbulent density, velocity, and magnetic fields. We find that lognormal density distributions aid shock propagation through clouds, increasing their velocity dispersion and producing filaments with expanded cross-sections and highly magnetized knots and subfilaments. In self-consistently turbulent scenarios, the ratio of filament to initial cloud magnetic energy densities is ∼1. The effect of Gaussian velocity fields is bound to the turbulence Mach number: Supersonic velocities trigger a rapid cloud expansion; subsonic velocities only have a minor impact. The role of turbulent magnetic fields depends on their tension and is similar to the effect of radiative losses: the stronger the magnetic field or the softer the gas equation of state, the greater the magnetic shielding at wind-filament interfaces and the suppression of Kelvin-Helmholtz instabilities. Overall, we show that including turbulence and magnetic fields is crucial to understanding cold gas entrainment in multiphase winds. While cloud porosity and supersonic turbulence enhance the acceleration of clouds, magnetic shielding protects them from ablation and causes Rayleigh-Taylor-driven subfilamentation. Wind-swept clouds in turbulent models reach distances ∼15-20 times their core radius and acquire bulk speeds ∼0.3-0.4 of the wind speed in one cloud-crushing time, which are three times larger than in non-turbulent models. In all simulations, the ratio of turbulent magnetic to kinetic energy densities asymptotes at ∼0.1-0.4, and convergence of all relevant dynamical properties requires at least 64 cells per cloud radius.

  17. Laboratory modeling of air-sea interaction under severe wind conditions

    Science.gov (United States)

    Troitskaya, Yuliya; Vasiliy, Kazakov; Nicolay, Bogatov; Olga, Ermakova; Mikhail, Salin; Daniil, Sergeev; Maxim, Vdovin

    2010-05-01

    Wind-wave interaction at extreme wind speed is of special interest now in connection with the problem of explanation of the sea surface drag saturation at the wind speed exceeding 30 m/s. The idea on saturation (and even reduction) of the coefficient of aerodynamic resistance of the sea surface at hurricane wind speed was first suggested by Emanuel (1995) on the basis of theoretical analysis of sensitivity of maximum wind speed in a hurricane to the ratio of the enthalpy and momentum exchange coefficients. Both field (Powell, Vickery, Reinhold, 2003, French et al, 2007, Black, et al, 2007) and laboratory (Donelan et al, 2004) experiments confirmed that at hurricane wind speed the sea surface drag coefficient is significantly reduced in comparison with the parameterization obtained at moderate to strong wind conditions. Two groups of possible theoretical mechanisms for explanation of the effect of the sea surface drag reduction can be specified. In the first group of models developed by Kudryavtsev & Makin (2007) and Kukulka,Hara Belcher (2007), the sea surface drag reduction is explained by peculiarities of the air flow over breaking waves. Another approach more appropriate for the conditions of developed sea exploits the effect of sea drops and sprays on the wind-wave momentum exchange (Andreas, 2004; Makin, 2005; Kudryavtsev, 2006). The main objective of this work is investigation of factors determining momentum exchange under high wind speeds basing on the laboratory experiment in a well controlled environment. The experiments were carried out in the Thermo-Stratified WInd-WAve Tank (TSWIWAT) of the Institute of Applied Physics. The parameters of the facility are as follows: airflow 0 - 25 m/s (equivalent 10-m neutral wind speed U10 up to 60 m/s), dimensions 10m x 0.4m x 0.7 m, temperature stratification of the water layer. Simultaneous measurements of the airflow velocity profiles and wind waves were carried out in the wide range of wind velocities. Airflow

  18. The Solar Wind and Geomagnetic Activity as a Function of Time Relative to Corotating Interaction Regions

    Science.gov (United States)

    McPherron, Robert L.; Weygand, James

    2006-01-01

    Corotating interaction regions during the declining phase of the solar cycle are the cause of recurrent geomagnetic storms and are responsible for the generation of high fluxes of relativistic electrons. These regions are produced by the collision of a high-speed stream of solar wind with a slow-speed stream. The interface between the two streams is easily identified with plasma and field data from a solar wind monitor upstream of the Earth. The properties of the solar wind and interplanetary magnetic field are systematic functions of time relative to the stream interface. Consequently the coupling of the solar wind to the Earth's magnetosphere produces a predictable sequence of events. Because the streams persist for many solar rotations it should be possible to use terrestrial observations of past magnetic activity to predict future activity. Also the high-speed streams are produced by large unipolar magnetic regions on the Sun so that empirical models can be used to predict the velocity profile of a stream expected at the Earth. In either case knowledge of the statistical properties of the solar wind and geomagnetic activity as a function of time relative to a stream interface provides the basis for medium term forecasting of geomagnetic activity. In this report we use lists of stream interfaces identified in solar wind data during the years 1995 and 2004 to develop probability distribution functions for a variety of different variables as a function of time relative to the interface. The results are presented as temporal profiles of the quartiles of the cumulative probability distributions of these variables. We demonstrate that the storms produced by these interaction regions are generally very weak. Despite this the fluxes of relativistic electrons produced during those storms are the highest seen in the solar cycle. We attribute this to the specific sequence of events produced by the organization of the solar wind relative to the stream interfaces. We also

  19. Wind Tunnel Model Design for Sonic Boom Studies of Nozzle Jet Flows with Shock Interactions

    Science.gov (United States)

    Cliff, Susan E.; Denison, Marie; Moini-Yekta, Shayan; Morr, Donald E.; Durston, Donald A.

    2016-01-01

    NASA and the U.S. aerospace industry are performing studies of supersonic aircraft concepts with low sonic boom pressure signatures. The computational analyses of modern aircraft designs have matured to the point where there is confidence in the prediction of the pressure signature from the front of the vehicle, but uncertainty remains in the aft signatures due to boundary layer and nozzle exhaust jet effects. Wind tunnel testing without inlet and nozzle exhaust jet effects at lower Reynolds numbers than in-flight make it difficult to accurately assess the computational solutions of flight vehicles. A wind tunnel test in the NASA Ames 9- by 7-Foot Supersonic Wind Tunnel is planned for February 2016 to address the nozzle jet effects on sonic boom. The experiment will provide pressure signatures of test articles that replicate waveforms from aircraft wings, tails, and aft fuselage (deck) components after passing through cold nozzle jet plumes. The data will provide a variety of nozzle plume and shock interactions for comparison with computational results. A large number of high-fidelity numerical simulations of a variety of shock generators were evaluated to define a reduced collection of suitable test models. The computational results of the candidate wind tunnel test models as they evolved are summarized, and pre-test computations of the final designs are provided.

  20. Interaction of suprathermal solar wind electron fluxes with sheared whistler waves: fan instability

    Directory of Open Access Journals (Sweden)

    C. Krafft

    Full Text Available Several in situ measurements performed in the solar wind evidenced that solar type III radio bursts were some-times associated with locally excited Langmuir waves, high-energy electron fluxes and low-frequency electrostatic and electromagnetic waves; moreover, in some cases, the simultaneous identification of energetic electron fluxes, Langmuir and whistler waves was performed. This paper shows how whistlers can be excited in the disturbed solar wind through the so-called "fan instability" by interacting with energetic electrons at the anomalous Doppler resonance. This instability process, which is driven by the anisotropy in the energetic electron velocity distribution along the ambient magnetic field, does not require any positive slope in the suprathermal electron tail and thus can account for physical situations where plateaued reduced electron velocity distributions were observed in solar wind plasmas in association with Langmuir and whistler waves. Owing to linear calculations of growth rates, we show that for disturbed solar wind conditions (that is, when suprathermal particle fluxes propagate along the ambient magnetic field, the fan instability can excite VLF waves (whistlers and lower hybrid waves with characteristics close to those observed in space experiments.

    Key words. Space plasma physics (waves and instabilities – Radio Science (waves in plasma – Solar physics, astrophysics and astronomy (radio emissions

  1. Wind turbine generator interaction with diesel generators on an isolated power system

    Science.gov (United States)

    Scott, G. W.; Wilreker, V. F.; Shaltens, R. K.

    1983-07-01

    The results of a dynamic interaction investigation to characterize any disturbances caused by interfacing the Mod 0A wind turbine (150 kW configuration) with the Block Island utility diesel generator grid are reported. The tests were run when only two diesel generators were on line, and attention was given to power, frequency, and voltage time profiles. The interconnected system was examined in the start-up and synchronization phase, normal shutdown and cut-out of the wind turbine, during fixed pitch generation, and during variable pitch operation. Governors were installed on the diesel generators to accommodate the presence of wind-derived electricity. The blade pitch control was set to maintain power at 150 kW or below. Power and voltage transients were insignificant during start-up and shutdown, and frequency aberrations were within the range caused by load fluctuations. It is concluded that wind turbine generation can be successfully implemented by an isolated utility, even with a significant penetration to the total grid output.

  2. Interaction of suprathermal solar wind electron fluxes with sheared whistler waves: fan instability

    Directory of Open Access Journals (Sweden)

    C. Krafft

    2003-07-01

    Full Text Available Several in situ measurements performed in the solar wind evidenced that solar type III radio bursts were some-times associated with locally excited Langmuir waves, high-energy electron fluxes and low-frequency electrostatic and electromagnetic waves; moreover, in some cases, the simultaneous identification of energetic electron fluxes, Langmuir and whistler waves was performed. This paper shows how whistlers can be excited in the disturbed solar wind through the so-called "fan instability" by interacting with energetic electrons at the anomalous Doppler resonance. This instability process, which is driven by the anisotropy in the energetic electron velocity distribution along the ambient magnetic field, does not require any positive slope in the suprathermal electron tail and thus can account for physical situations where plateaued reduced electron velocity distributions were observed in solar wind plasmas in association with Langmuir and whistler waves. Owing to linear calculations of growth rates, we show that for disturbed solar wind conditions (that is, when suprathermal particle fluxes propagate along the ambient magnetic field, the fan instability can excite VLF waves (whistlers and lower hybrid waves with characteristics close to those observed in space experiments.Key words. Space plasma physics (waves and instabilities – Radio Science (waves in plasma – Solar physics, astrophysics and astronomy (radio emissions

  3. Identifying Wave-Particle Interactions in the Solar Wind using Statistical Correlations

    Science.gov (United States)

    Broiles, T. W.; Jian, L. K.; Gary, S. P.; Lepri, S. T.; Stevens, M. L.

    2017-12-01

    Heavy ions are a trace component of the solar wind, which can resonate with plasma waves, causing heating and acceleration relative to the bulk plasma. While wave-particle interactions are generally accepted as the cause of heavy ion heating and acceleration, observations to constrain the physics are lacking. In this work, we statistically link specific wave modes to heavy ion heating and acceleration. We have computed the Fast Fourier Transform (FFT) of transverse and compressional magnetic waves between 0 and 5.5 Hz using 9 days of ACE and Wind Magnetometer data. The FFTs are averaged over plasma measurement cycles to compute statistical correlations between magnetic wave power at each discrete frequency, and ion kinetic properties measured by ACE/SWICS and Wind/SWE. The results show that lower frequency transverse oscillations ( 0.4 Hz) are positively correlated with enhancements in the heavy ion thermal and drift speeds. Moreover, the correlation results for the He2+ and O6+ were similar on most days. The correlations were often weak, but most days had some frequencies that correlated with statistical significance. This work suggests that the solar wind heavy ions are possibly being heated and accelerated by both transverse and compressional waves at different frequencies.

  4. A New Axisymmetric MHD Model of the Interaction of the Solar Wind with Venus

    Science.gov (United States)

    DeZeeuw, Darren L.; Nagy, Andrew F.; Gombosi, Tamas I.; Powell, Kenneth G.; Luhmann, Janet G.

    1996-01-01

    A new two-dimensional axisymmetric MHD model is used to study the interaction of the solar wind with Venus under conditions where the interplanetary field is approximately aligned with the solar wind velocity. This numerical model solves the MHD transport equations for density, velocity, pressure, and magnetic field on an adaptively refined, unstructured grid system. This use of an adaptive grid allows high spatial resolution in regions of large density/velocity gradients and yet can be run on a workstation. The actual grid sizes vary from about 0.06 R(sub v) near the bowshock to 2 R(sub v) in the unperturbed solar wind. The results of the calculations are compared with observed magnetic field values obtained from the magnetometer on the Pioneer Venus Orbiter, at a time when the angle between the solar wind velocity vector and the interplanetary magnetic field (IMF) was only 7.6 deg. Good qualitative agreement between the observed and calculated field behavior is found. The overall results suggest that the induced magnetotail disappears when the IMF is radial for an extended time period and implies that it weakens when the field rotated through a near-radial orientation.

  5. Herbivores alter plant-wind interactions by acting as a point mass on leaves and by removing leaf tissue.

    Science.gov (United States)

    Kothari, Adit R; Burnett, Nicholas P

    2017-09-01

    In nature, plants regularly interact with herbivores and with wind. Herbivores can wound and alter the structure of plants, whereas wind can exert aerodynamic forces that cause the plants to flutter or sway. While herbivory has many negative consequences for plants, fluttering in wind can be beneficial for plants by facilitating gas exchange and loss of excess heat. Little is known about how herbivores affect plant motion in wind. We tested how the mass of an herbivore resting on a broad leaf of the tulip tree Liriodendron tulipifera , and the damage caused by herbivores, affected the motion of the leaf in wind. For this, we placed mimics of herbivores on the leaves, varying each herbivore's mass or position, and used high-speed video to measure how the herbivore mimics affected leaf movement and reconfiguration at two wind speeds inside a laboratory wind tunnel. In a similar setup, we tested how naturally occurring herbivore damage on the leaves affected leaf movement and reconfiguration. We found that the mass of an herbivore resting on a leaf can change that leaf's orientation relative to the wind and interfere with the ability of the leaf to reconfigure into a smaller, more streamlined shape. A large herbivore load slowed the leaf's fluttering frequency, while naturally occurring damage from herbivores increased the leaf's fluttering frequency. We conclude that herbivores can alter the physical interactions between wind and plants by two methods: (1) acting as a point mass on the plant while it is feeding and (2) removing tissue from the plant. Altering a plant's interaction with wind can have physical and physiological consequences for the plant. Thus, future studies of plants in nature should consider the effect of herbivory on plant-wind interactions, and vice versa.

  6. Wind turbine generator interaction with conventional diesel generators on Block Island, Rhode Island. Volume 1: Executive summary

    Science.gov (United States)

    Wilreker, V. F.; Stiller, P. H.; Scott, G. W.; Kruse, V. J.; Smith, R. F.

    1984-02-01

    Primary results are summarized for a three-part study involving the effects of connecting a MOD-OA wind turbine generator to an isolated diesel power system. The MOD-OA installation considered was the third of four experimental nominal 200 kW wind turbines connected to various utilities under the Federal Wind Energy Program and was characterized by the highest wind energy penetration levels of four sites. The study analyses address: fuel displacement, dynamic interaction, and three modes of reactive power control. These analyses all have as their basis the results of the data acquisition program conducted on Block Island, Rhode Island.

  7. REGIONAL AIR-SEA INTERACTION (RASI) GAP WIND AND COASTAL UPWELLING EVENTS CLIMATOLOGY GULF OF PANAMA, PANAMA V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Regional Air-Sea Interactions (RASI) Gap Wind and Coastal Upwelling Events Climatology datasets were created using an automated intelligent algorithm which...

  8. REGIONAL AIR-SEA INTERACTION (RASI) GAP WIND AND COASTAL UPWELLING EVENTS CLIMATOLOGY GULF OF TEHUANTEPEC, MEXICO V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Regional Air-Sea Interactions (RASI) Gap Wind and Coastal Upwelling Events Climatology datasets were created using an automated intelligent algorithm which...

  9. REGIONAL AIR-SEA INTERACTION (RASI) GAP WIND AND COASTAL UPWELLING EVENTS CLIMATOLOGY GULF OF PAPAGAYO, COSTA RICA V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Regional Air-Sea Interactions (RASI) Gap Wind and Coastal Upwelling Events Climatology datasets were created using an automated intelligent algorithm which...

  10. REGIONAL AIR-SEA INTERACTION (RASI) GAP WIND AND COASTAL UPWELLING EVENTS CLIMATOLOGY GULF OF PAPAGAYO, COSTA RICA V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Regional Air-Sea Interactions (RASI) Gap Wind and Coastal Upwelling Events Climatology Gulf of Papagayo, Costa Rica dataset was created using an automated...

  11. An Analysis of Wind Power Development in the Town of Hull, MA, Appendix 2: LaCapra Financial Study

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Christopher

    2013-06-30

    The financial analysis and summary results presented in this document represent a first cut at an economic assessment of the proposed Hull Offshore Wind Project. Wind turbine price increases have outpaced the materials and labor price pressures faced by nonrenewable power plant developers due to increased demands on a limited pool of turbine manufacturers and offshore installation companies. Moreover, given the size of the proposed offshore facility, it may be difficult to contract with turbine manufacturers and/or foundation companies given the size and scope of competing worldwide demand. The results described in this report assume that such conditions will not significantly impact the prices that will have to be received from the output of the project; rather, the project size may require as a prerequisite that Hull be able to piggyback on other offshore efforts. The financial estimates provided here necessarily feature a range due to uncertainty in a number of project assumptions as well as overall uncertainty in offshore wind costs. Nevertheless, taken together, the analysis provides a ballpark revenue requirement of approximately $157/MWh for the municipal financing option, with higher estimates possible assuming escalation in costs to levels higher than assumed here.

  12. Modelling the solar wind interaction with Mercury by a quasi-neutral hybrid model

    Directory of Open Access Journals (Sweden)

    E. Kallio

    Full Text Available Quasi-neutral hybrid model is a self-consistent modelling approach that includes positively charged particles and an electron fluid. The approach has received an increasing interest in space plasma physics research because it makes it possible to study several plasma physical processes that are difficult or impossible to model by self-consistent fluid models, such as the effects associated with the ions’ finite gyroradius, the velocity difference between different ion species, or the non-Maxwellian velocity distribution function. By now quasi-neutral hybrid models have been used to study the solar wind interaction with the non-magnetised Solar System bodies of Mars, Venus, Titan and comets. Localized, two-dimensional hybrid model runs have also been made to study terrestrial dayside magnetosheath. However, the Hermean plasma environment has not yet been analysed by a global quasi-neutral hybrid model.

    In this paper we present a new quasi-neutral hybrid model developed to study various processes associated with the Mercury-solar wind interaction. Emphasis is placed on addressing advantages and disadvantages of the approach to study different plasma physical processes near the planet. The basic assumptions of the approach and the algorithms used in the new model are thoroughly presented. Finally, some of the first three-dimensional hybrid model runs made for Mercury are presented.

    The resulting macroscopic plasma parameters and the morphology of the magnetic field demonstrate the applicability of the new approach to study the Mercury-solar wind interaction globally. In addition, the real advantage of the kinetic hybrid model approach is to study the property of individual ions, and the study clearly demonstrates the large potential of the approach to address these more detailed issues by a quasi-neutral hybrid model in the future.

    Key words. Magnetospheric physics

  13. 3D Modeling of Forbidden Line Emission in the Binary Wind Interaction Region of Eta Carinae

    Science.gov (United States)

    Madura, Thomas; Gull, T. R.; Owocki, S.; Okazaki, A. T.; Russell, C. M. P.

    2010-01-01

    We present recent work using three-dimensional (3D) Smoothed Particle Hydrodynamics (SPH) simulations to model the high ([Fe III], [Ar III], [Ne III] and [S III]) and low ([Fe II], [Ni II]) ionization forbidden emission lines observed in Eta Carinae using the HST/STIS. These structures are interpreted as the time-averaged, outer extensions of the primary wind and the wind-wind interaction region directly excited by the FUV of the hot companion star of this massive binary system. We discuss how analyzing the results of the 3D SPH simulations and synthetic slit spectra and comparing them to the spectra obtained with the HST/STIS helps us determine the absolute orientation of the binary orbit and helps remove the degeneracy inherent to models based solely on the observed RXTE X-ray light curve. A key point of this work is that spatially resolved observations like those with HST/STIS and comparison to 3D models are necessary to determine the alignment or misalignment of the orbital angular momentum axis with the Homunculus, or correspondingly, the alignment of the orbital plane with the Homunculus skirt.

  14. Investigating Power System Primary and Secondary Reserve Interaction under High Wind Power Penetration

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yingchen [National Renewable Energy Lab. (NREL), Golden, CO (United States); Tan, Jin [National Renewable Energy Lab. (NREL), Golden, CO (United States); Krad, Ibrahim [National Renewable Energy Lab. (NREL), Golden, CO (United States); Yang, Rui [National Renewable Energy Lab. (NREL), Golden, CO (United States); Gevorgian, Vahan [National Renewable Energy Lab. (NREL), Golden, CO (United States); Ela, Erik [Electric Power Research Inst. (EPRI), Knoxville, TN (United States)

    2016-12-01

    Power system frequency needs to be maintained close to its nominal value at all times to successfully balance load and generation and maintain system reliability. Adequate primary frequency response and secondary frequency response are the primary forces to correct an energy imbalance at the second-to-minute level. As wind energy becomes a larger portion of the world's energy portfolio, there is an increased need for wind to provide frequency response. This paper addresses one of the major concerns about using wind for frequency regulation: the unknown factor of the interaction between primary and secondary reserves. The lack of a commercially available tool to model this has limited the energy industry's understanding of when the depletion of primary reserves will impact the performance of secondary response or vice versa. This paper investigates the issue by developing a multi-area frequency response integration tool with combined primary and secondary capabilities. The simulation is conducted in close coordination with economical energy scheduling scenarios to ensure credible simulation results.

  15. Wind turbine wake interactions at field scale: An LES study of the SWiFT facility

    International Nuclear Information System (INIS)

    Yang, Xiaolei; Boomsma, Aaron; Sotiropoulos, Fotis; Barone, Matthew

    2014-01-01

    The University of Minnesota Virtual Wind Simulator (VWiS) code is employed to simulate turbine/atmosphere interactions in the Scaled Wind Farm Technology (SWiFT) facility developed by Sandia National Laboratories in Lubbock, TX, USA. The facility presently consists of three turbines and the simulations consider the case of wind blowing from South such that two turbines are in the free stream and the third turbine in the direct wake of one upstream turbine with separation of 5 rotor diameters. Large-eddy simulation (LES) on two successively finer grids is carried out to examine the sensitivity of the computed solutions to grid refinement. It is found that the details of the break-up of the tip vortices into small-scale turbulence structures can only be resolved on the finer grid. It is also shown that the power coefficient C P of the downwind turbine predicted on the coarse grid is somewhat higher than that obtained on the fine mesh. On the other hand, the rms (root-mean-square) of the C P fluctuations are nearly the same on both grids, although more small-scale turbulence structures are resolved upwind of the downwind turbine on the finer grid

  16. Ultrafast Kelvin waves in the MLT airglow and wind, and their interaction with the atmospheric tides

    Science.gov (United States)

    Egito, Fabio; Arlen Buriti, Ricardo; Fragoso Medeiros, Amauri; Takahashi, Hisao

    2018-02-01

    Airglow and wind measurements from the Brazilian equatorial region were used to investigate the presence and the effects of the 3-4-day ultrafast Kelvin waves in the MLT. The airglow integrated intensities of the OI557.7 nm, O2b(0-1) and OH(6-2) emissions, as well as the OH rotational temperature, were measured by a multichannel photometer, and the zonal and meridional wind components between 80 and 100 km were obtained from a meteor radar. Both instruments are installed in the Brazilian equatorial region at São João do Cariri (7.4° S, 36.5° W). Data from 2005 were used in this study. The 3-4-day oscillations appear intermittently throughout the year in the airglow. They were identified in January, March, July, August and October-November observations. The amplitudes induced by the waves in the airglow range from 26 to 40 % in the OI557.7 nm, 17 to 43 % in the O2b(0-1) and 15 to 20 % in the OH(6-2) emissions. In the OH rotational temperature, the amplitudes were from 4 to 6 K. Common 3-4-day oscillations between airglow and neutral wind compatible with ultrafast Kelvin waves were observed in March, August and October-November. In these cases, the amplitudes in the zonal wind were found to be between 22 and 28 m s-1 and the vertical wavelength ranges from 44 to 62 km. Evidence of the nonlinear interaction between the ultrafast Kelvin wave and diurnal tide was observed.

  17. Ultrafast Kelvin waves in the MLT airglow and wind, and their interaction with the atmospheric tides

    Directory of Open Access Journals (Sweden)

    F. Egito

    2018-02-01

    Full Text Available Airglow and wind measurements from the Brazilian equatorial region were used to investigate the presence and the effects of the 3–4-day ultrafast Kelvin waves in the MLT. The airglow integrated intensities of the OI557.7 nm, O2b(0-1 and OH(6-2 emissions, as well as the OH rotational temperature, were measured by a multichannel photometer, and the zonal and meridional wind components between 80 and 100 km were obtained from a meteor radar. Both instruments are installed in the Brazilian equatorial region at São João do Cariri (7.4° S, 36.5° W. Data from 2005 were used in this study. The 3–4-day oscillations appear intermittently throughout the year in the airglow. They were identified in January, March, July, August and October–November observations. The amplitudes induced by the waves in the airglow range from 26 to 40 % in the OI557.7 nm, 17 to 43 % in the O2b(0-1 and 15 to 20 % in the OH(6-2 emissions. In the OH rotational temperature, the amplitudes were from 4 to 6 K. Common 3–4-day oscillations between airglow and neutral wind compatible with ultrafast Kelvin waves were observed in March, August and October–November. In these cases, the amplitudes in the zonal wind were found to be between 22 and 28 m s−1 and the vertical wavelength ranges from 44 to 62 km. Evidence of the nonlinear interaction between the ultrafast Kelvin wave and diurnal tide was observed.

  18. Combined Ulysses Solar Wind and SOHO Coronal Observations of Several West Limb Coronal Mass Ejections. Appendix 8

    Science.gov (United States)

    Funsten, H. O.; Gosling, J. T.; Riley, P.; St.Cyr, O. C.; Forsyth, R. J.; Howard, R. A.; Schwenn, R.

    2001-01-01

    From October 1996 to January 1997, Ulysses was situated roughly above the west limb of the Sun as observed from Earth at a heliocentric distance of about 4.6 AU and a latitude of about 25 deg. This presents the first opportunity to compare Solar and Heliospheric Observatory (SOHO) limb observations of coronal mass ejections (CMEs) directly with their solar wind counterparts far from the Sun using the Ulysses data. During this interval, large eruptive events were observed above the west limb of the Sun by the Large Angle Spectrometric Coronagraph (LASCO) on SOHO on October 5, November 28, and December 21-25, 1996. Using the combined plasma and magnetic field data from Ulysses, the October 5 event was clearly identified by several distinguishing signatures as a CME. The November 28 event was also identified as a CME that trailed fast ambient solar wind, although it was identified only by an extended interval of counterstreaming suprathermal electrons. The December 21 event was apparently characterized by a six-day interval of nearly radial field and a plasma rarefaction. For the numerous eruptive events observed by the LASCO coronagraph during December 23-25, Ulysses showed no distinct, CMEs, perhaps because of intermingling of two or more of the eruptive events. By mapping the Ulysses observations back in time to the Sun assuming a constant flow speed, we have identified intervals of plasma that were accelerated or decelerated between the LASCO and Ulysses observations.

  19. Electromagnetic Particle-in-Cell Simulations of the Solar Wind Interaction with Lunar Magnetic Anomalies

    Science.gov (United States)

    Deca, J.; Divin, A.; Lapenta, G.; Lembège, B.; Markidis, S.; Horányi, M.

    2014-04-01

    We present the first three-dimensional fully kinetic and electromagnetic simulations of the solar wind interaction with lunar crustal magnetic anomalies (LMAs). Using the implicit particle-in-cell code iPic3D, we confirm that LMAs may indeed be strong enough to stand off the solar wind from directly impacting the lunar surface forming a mini-magnetosphere, as suggested by spacecraft observations and theory. In contrast to earlier magnetohydrodynamics and hybrid simulations, the fully kinetic nature of iPic3D allows us to investigate the space charge effects and in particular the electron dynamics dominating the near-surface lunar plasma environment. We describe for the first time the interaction of a dipole model centered just below the lunar surface under plasma conditions such that only the electron population is magnetized. The fully kinetic treatment identifies electromagnetic modes that alter the magnetic field at scales determined by the electron physics. Driven by strong pressure anisotropies, the mini-magnetosphere is unstable over time, leading to only temporal shielding of the surface underneath. Future human exploration as well as lunar science in general therefore hinges on a better understanding of LMAs.

  20. Interaction of a strong stellar wind with a mutiphase interstellar medium

    International Nuclear Information System (INIS)

    Wolff, M.T.

    1986-01-01

    The interaction of a strong stellar wind with the interstellar medium produces a hot, low density cavity surrounded by a swept-up shell of gas. This cavity-plus-shell structure is collectively called an interstellar bubble. In calculations prior to this work, researchers assumed that the interstellar medium surrounding the wind-blowing star was described by a constant density and temperature (i.e., was homogeneous). This dissertation improves on these earlier calculations by assuming that the interstellar medium surrounding the star is inhomogeneous or multiphase. Gas flows are modeled by assuming that the inhomogeneous phases of the interstellar medium (the clouds) and the intercloud gas form two distinct but interacting fluid that can exchange mass momentum and energy with each other. In one set of calculations, it is assumed that thermal conductive evaporation of clouds brought about by the clouds sitting inside a region of hot (T ≅ 10 6 K) gas is the only mass exchange process operation between the clouds and intercloud fluid. It was found that the mass injection from the clouds to the intercloud gas via the process of thermal evaporation can significantly modify the structure of the interstellar bubble from that found in previous studies

  1. Pluto's interaction with its space environment: Solar wind, energetic particles, and dust.

    Science.gov (United States)

    Bagenal, F; Horányi, M; McComas, D J; McNutt, R L; Elliott, H A; Hill, M E; Brown, L E; Delamere, P A; Kollmann, P; Krimigis, S M; Kusterer, M; Lisse, C M; Mitchell, D G; Piquette, M; Poppe, A R; Strobel, D F; Szalay, J R; Valek, P; Vandegriff, J; Weidner, S; Zirnstein, E J; Stern, S A; Ennico, K; Olkin, C B; Weaver, H A; Young, L A

    2016-03-18

    The New Horizons spacecraft carried three instruments that measured the space environment near Pluto as it flew by on 14 July 2015. The Solar Wind Around Pluto (SWAP) instrument revealed an interaction region confined sunward of Pluto to within about 6 Pluto radii. The region's surprisingly small size is consistent with a reduced atmospheric escape rate, as well as a particularly high solar wind flux. Observations from the Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) instrument suggest that ions are accelerated and/or deflected around Pluto. In the wake of the interaction region, PEPSSI observed suprathermal particle fluxes equal to about 1/10 of the flux in the interplanetary medium and increasing with distance downstream. The Venetia Burney Student Dust Counter, which measures grains with radii larger than 1.4 micrometers, detected one candidate impact in ±5 days around New Horizons' closest approach, indicating an upper limit of <4.6 kilometers(-3) for the dust density in the Pluto system. Copyright © 2016, American Association for the Advancement of Science.

  2. Interaction between surface wind and ocean circulation in the Carolina Capes in a coupled low-order model

    Energy Technology Data Exchange (ETDEWEB)

    Xie, L.; Pietrafesa, L.J.; Raman, S.

    1997-03-18

    Interactions between surface winds and ocean currents over an east-coast continental shelf are studied using a simple mathematical model. The model physics include cross-shelf advection of sea surface temperature (SST) by Ekman drift, upwelling due to Ekman transport divergence, differential heating of the low-level atmosphere by a cross-shelf SST gradient, and the Coriolis effect. Additionally, the effects of diabatic cooling of surface waters due to air-sea heat exchange and of the vertical density stratification on the thickness of the upper ocean Ekman layer are considered. The model results are qualitatively consistent with observed wind-driven coastal ocean circulation and surface wind signatures induced by SST. This simple model also demonstrates that two-way air-sea interaction plays a significant role in the subtidal frequency variability of coastal ocean circulation and mesoscale variability of surface wind fields over coastal waters.

  3. Wind turbine generator interaction with conventional diesel generators on Block Island, Rhode Island. Volume 2: Data analysis

    Science.gov (United States)

    Wilreker, V. F.; Stiller, P. H.; Scott, G. W.; Kruse, V. J.; Smith, R. F.

    1984-02-01

    Assessing the performance of a MOD-OA horizontal axis wind turbine connected to an isolated diesel utility, a comprehensive data measurement program was conducted on the Block Island Power Company installation on Block Island, Rhode Island. The detailed results of that program focusing on three principal areas of (1) fuel displacement (savings), (2) dynamic interaction between the diesel utility and the wind turbine, (3) effects of three models of wind turbine reactive power control are presented. The approximate two month duration of the data acquisition program conducted in the winter months (February into April 1982) revealed performance during periods of highest wind energy penetration and hence severity of operation. Even under such conditions fuel savings were significant resulting in a fuel reduction of 6.7% while the MOD-OA was generating 10.7% of the total electrical energy. Also, electrical disturbance and interactive effects were of an acceptable level.

  4. Three-wave interactions in a gravity-capillary range of wind waves

    Science.gov (United States)

    Kosnik, M.; Dulov, V.; Kudryavtsev, V.

    2009-04-01

    The effects of three-wave interactions on forming of short wind waves spectrum are investigated. Wavenumber spectrum in gravity-capillary and capillary range is found as a result of evolution of initial arbitrary spectrum under the influence of assigned sources of kinetic equation. Three-wave interactions are taken into account using exact collision integral without any additional assumptions simplifying a problem. Model validity is proved by reproducing Zaharov & Filonenko (1967) theoretical spectra describing the "energy equipartition" and "inertial interval" cases. Numerical calculations show that the main role of three-wave interactions consists in energy transfer from short gravity waves to waves of smaller lengths. The prominent feature of most of resulting spectra is a dip on curvature spectrum in the vicinity of phase speed minimum. Wind forcing, viscous dissipation and mechanism of generation of parasitic capillaries are considered in a number of calculations using parameterization for corresponding sources by Kudryavtsev, Makin, Chapron, 1999. The necessity of additional nonlinear dissipation terms in kinetic equation for short gravity and capillary waves is revealed. The results of calculation with this realistic parameterization of kinetic equation sources show that, when accounted, nonlinear dissipation and parasitic capillaries terms play much more significant part in capillary range than wave-wave interactions. The latter are important only in phase speed minimum area where the typical dip remains at the same wavenumber in all numerical experiments. This work was supported by the EU under the projects INTAS 05-1000008-8014, INTAS/ESA 06-1000025-9264 and Contract # SST5 CT 2006 031001 (MONRUK) of FP6.

  5. County-Level Climate Uncertainty for Risk Assessments: Volume 18 Appendix Q - Historical Maximum Near-Surface Wind Speed.

    Energy Technology Data Exchange (ETDEWEB)

    Backus, George A.; Lowry, Thomas Stephen; Jones, Shannon M; Walker, La Tonya Nicole; Roberts, Barry L; Malczynski, Leonard A.

    2017-06-01

    This report uses the CMIP5 series of climate model simulations to produce country- level uncertainty distributions for use in socioeconomic risk assessments of climate change impacts. It provides appropriate probability distributions, by month, for 169 countries and autonomous-areas on temperature, precipitation, maximum temperature, maximum wind speed, humidity, runoff, soil moisture and evaporation for the historical period (1976-2005), and for decadal time periods to 2100. It also provides historical and future distributions for the Arctic region on ice concentration, ice thickness, age of ice, and ice ridging in 15-degree longitude arc segments from the Arctic Circle to 80 degrees latitude, plus two polar semicircular regions from 80 to 90 degrees latitude. The uncertainty is meant to describe the lack of knowledge rather than imprecision in the physical simulation because the emphasis is on unfalsified risk and its use to determine potential socioeconom ic impacts. The full report is contained in 27 volumes.

  6. Wind power

    International Nuclear Information System (INIS)

    Gipe, P.

    2007-01-01

    , graphics, and weighty appendixes make it an invaluable reference for everyone interested in the emerging trend of wind power and renewable energy. (author)

  7. Solar Wind Plasma Interaction with Asteroid 16 Psyche: Implication for Formation Theories

    Science.gov (United States)

    Fatemi, Shahab; Poppe, Andrew R.

    2018-01-01

    The asteroid 16 Psyche is a primitive metal-rich asteroid that has not yet been visited by spacecraft. Based on remote observations, Psyche is most likely composed of iron and nickel metal; however, the history of its formation and solidification is still unknown. If Psyche is a remnant core of a differentiated planetesimal exposed by collisions, it opens a unique window toward understanding the cores of the terrestrial bodies, including the Earth and Mercury. If not, it is perhaps a reaccreted rubble pile that has never melted. In the former case, Psyche may have a remanent, dipolar magnetic field; in the latter case, Psyche may have no intrinsic field, but nevertheless would be a conductive object in the solar wind. We use Advanced Modeling Infrastructure in Space Simulation (AMITIS), a three-dimensional GPU-based hybrid model of plasma that self-consistently couples the interior electromagnetic response of Psyche (i.e., magnetic diffusion) to its ambient plasma environment in order to quantify the different interactions under these two cases. The model results provide estimates for the electromagnetic environment of Psyche, showing that the magnetized case and the conductive case present very different signatures in the solar wind. These results have implications for an accurate interpretation of magnetic field observations by NASA's Discovery mission (Psyche mission) to the asteroid 16 Psyche.

  8. Interaction of the solar wind with the planet Mars: Phobos 2 magnetic field observations

    International Nuclear Information System (INIS)

    Riedler, W.; Schwingenschuh, K.; Lichtenegger, H.

    1991-01-01

    The magnetometers on board the Phobos 2 spacecraft provided the opportunity to study the magnetic environment around Mars, including regions which have never been explored before, such as at low altitudes (down to 850 km above the surface of Mars) and in the tail. The data revealed a bow shock, characterized by a distinct jump in the magnetic field strength and a boundary denoted ''planetopause'', where the level of turbulence of the magnetic field changes. Inside the planetopause the field remains quiet. Some of the main characteristics of the bow shock and the magnetosheath can be reproduced by computer simulations within the framework of a gas-dynamic model using the observed planetopause as an obstacle for the incoming solar wind. In many spacecraft orbits around Mars, reversals of the B x -component were found which are typical for tail crossings. A first analysis of the tail data from the circular orbits at a distance of 2.8 Mars radii showed several cases where the reversal of the tail lobes was controlled by the IMF. This supports the idea of an induced character of the solar wind interaction with Mars outside a distance of about 2.8 Mars radii. However, there are certain features in the magnetic field data which could be interpreted as traces of a weak Martian intrinsic field. (author)

  9. An electrodynamic model of the solar wind interaction with the ionospheres of Mars and Venus

    International Nuclear Information System (INIS)

    Cloutier, P.A.; Daniell, R.E. Jr.

    1979-01-01

    the electrodynamic model for the solar wind interaction with non-magnetic planets (Cloutier and Daniell, Planet. Space Sci. 21, 463, 1973; Daniell and Cloutier, Planet. Space Sci. 25, 621, 1977) is modified to include the effects of non-ohmic currents in the upper ionosphere. The model is then used to calculate convection patterns induced by the solar wind in the ionospheres of Mars and Venus. For Mars the observations of the neutral mass spectrometer or Vikings 1 and 2 provided the neutral atmosphere. Model calculations reproduced the retarding potential analyzer data and indicate that the ionosphere above about 200 km is probably controlled by convection rather than chemistry or diffusion. For Venus a model atmosphere based on Dickenson and Ridley, J. Atmos. Sci. 32, 1219 (1975) and Mayr et al., J. Geophys. Res. 83, 4411 (1978) was used. The resulting model calculations were compared to radio occultation data from Mariners 5 and 10 and Venera 9 which represent extremes in the variability of the upper Cytherean ionosphere. The model calculations are shown to fall within this variation. These results represent the state of the theory immediately prior to the Pioneer-Venus encounter. (author)

  10. Two-way Fluid-Structure Interaction Simulation of a Micro Horizontal Axis Wind Turbine

    Directory of Open Access Journals (Sweden)

    Yi-Bao Chen

    2015-01-01

    Full Text Available A two-way Fluid-Structure Interaction (FSI analyses performed on a micro horizontal axis wind turbine (HAWT which coupled the CFX solver with Structural solver in ANSYS Workbench was conducted in this paper. The partitioned approach-based non-conforming mesh methods and the k-ε turbulence model were adopted to perform the study. Both the results of one-way and two-way FSI analyses were presented and compared with each other, and discrepancy of the results, especially the mechanical properties, were analysed. Grid convergence which is crucial to the results was performed, and the relationship between the inner flow field domain (rotational domain and the number of grids (number of cells, elements was verified for the first time. Dynamical analyses of the wind turbine were conducted using the torque as a reference value, to verify the rationality of the model which dominates the accuracy of results. The optimal case was verified and used to conduct the study, thus, the results derived from the simulation of the FSI are accurate and credible.

  11. Multiple tuned mass damper based vibration mitigation of offshore wind turbine considering soil-structure interaction

    Science.gov (United States)

    Hussan, Mosaruf; Sharmin, Faria; Kim, Dookie

    2017-08-01

    The dynamics of jacket supported offshore wind turbine (OWT) in earthquake environment is one of the progressing focuses in the renewable energy field. Soil-structure interaction (SSI) is a fundamental principle to analyze stability and safety of the structure. This study focuses on the performance of the multiple tuned mass damper (MTMD) in minimizing the dynamic responses of the structures objected to seismic loads combined with static wind and wave loads. Response surface methodology (RSM) has been applied to design the MTMD parameters. The analyses have been performed under two different boundary conditions: fixed base (without SSI) and flexible base (with SSI). Two vibration modes of the structure have been suppressed by multi-mode vibration control principle in both cases. The effectiveness of the MTMD in reducing the dynamic response of the structure is presented. The dynamic SSI plays an important role in the seismic behavior of the jacket supported OWT, especially resting on the soft soil deposit. Finally, it shows that excluding the SSI effect could be the reason of overestimating the MTMD performance.

  12. Interaction Between the Atmospheric Boundary Layer and Wind Energy: From Continental-Scale to Turbine-Scale

    Science.gov (United States)

    St. Martin, Clara Mae

    Wind turbines and groups of wind turbines, or "wind plants", interact with the complex and heterogeneous boundary layer of the atmosphere. We define the boundary layer as the portion of the atmosphere directly influenced by the surface, and this layer exhibits variability on a range of temporal and spatial scales. While early developments in wind energy could ignore some of this variability, recent work demonstrates that improved understanding of atmosphere-turbine interactions leads to the discovery of new ways to approach turbine technology development as well as processes such as performance validation and turbine operations. This interaction with the atmosphere occurs at several spatial and temporal scales from continental-scale to turbine-scale. Understanding atmospheric variability over continental-scales and across plants can facilitate reliance on wind energy as a baseload energy source on the electrical grid. On turbine scales, understanding the atmosphere's contribution to the variability in power production can improve the accuracy of power production estimates as we continue to implement more wind energy onto the grid. Wind speed and directional variability within a plant will affect wind turbine wakes within the plants and among neighboring plants, and a deeper knowledge of these variations can help mitigate effects of wakes and possibly even allow the manipulation of these wakes for increased production. Herein, I present the extent of my PhD work, in which I studied outstanding questions at these scales at the intersections of wind energy and atmospheric science. My work consists of four distinct projects. At the coarsest scales, I analyze the separation between wind plant sites needed for statistical independence in order to reduce variability for grid-integration of wind. At lower wind speeds, periods of unstable and more turbulent conditions produce more power than periods of stable and less turbulent conditions, while at wind speeds closer to

  13. Low-frequency magnetic field fluctuations in Venus' solar wind interaction region: Venus Express observations

    Directory of Open Access Journals (Sweden)

    L. Guicking

    2010-04-01

    Full Text Available We investigate wave properties of low-frequency magnetic field fluctuations in Venus' solar wind interaction region based on the measurements made on board the Venus Express spacecraft. The orbit geometry is very suitable to investigate the fluctuations in Venus' low-altitude magnetosheath and mid-magnetotail and provides an opportunity for a comparative study of low-frequency waves at Venus and Mars. The spatial distributions of the wave properties, in particular in the dayside and nightside magnetosheath as well as in the tail and mantle region, are similar to observations at Mars. As both planets do not have a global magnetic field, the interaction process of the solar wind with both planets is similar and leads to similar instabilities and wave structures. We focus on the spatial distribution of the wave intensity of the fluctuating magnetic field and detect an enhancement of the intensity in the dayside magnetosheath and a strong decrease towards the terminator. For a detailed investigation of the intensity distribution we adopt an analytical streamline model to describe the plasma flow around Venus. This allows displaying the evolution of the intensity along different streamlines. It is assumed that the waves are generated in the vicinity of the bow shock and are convected downstream with the turbulent magnetosheath flow. However, neither the different Mach numbers upstream and downstream of the bow shock, nor the variation of the cross sectional area and the flow velocity along the streamlines play probably an important role in order to explain the observed concentration of wave intensity in the dayside magnetosheath and the decay towards the nightside magnetosheath. But, the concept of freely evolving or decaying turbulence is in good qualitative agreement with the observations, as we observe a power law decay of the intensity along the streamlines. The observations support the assumption of wave convection through the magnetosheath, but

  14. THE EVOLUTION OF THE FILM ANALYSIS OF INTERACTION RECORD (FAIR) FROM THE AMIDON-FLANDERS INTERACTION ANALYSIS. APPENDIX G.

    Science.gov (United States)

    BALDWIN, PATRICIA

    A DETAILED LISTING IS GIVEN OF THE REVISIONS THAT WERE MADE TO THE AMIDON-FLANDERS INTERACTION ANALYSIS SCALE WHILE THE FILM ANALYSIS OF INTERACTION RECORD (FAIR) SCALE WAS BEING DEVELOPED. COMMENTS ARE GIVEN FOR GUIDANCE IN THE USE OF SOME OF THE RATINGS ALONG WITH SOME GROUND RULES AND GUIDELINES FOR MAKING A FILM RATING. RELATED REPORTS ARE AA…

  15. Holistic genetic optimization of a Generalized Multiple Discrete Interaction Approximation for wind waves

    Science.gov (United States)

    Tolman, Hendrik L.; Grumbine, Robert W.

    2013-10-01

    A key element of wind wave models is the parameterization of the resonant nonlinear interactions between spectral wave components. In a companion paper a new Generalized Multiple Discrete Interaction Approximation (GMD) has been developed. The present paper addresses the optimization of the free parameters of the GMD. A holistic optimization approach is used where full model integration results are optimized. Fifteen objective metrics are used, defined to measure the accuracy of a model using the GMD relative to a model using the full (exact) interactions. Due to the large number of free parameters to be optimized, and due to the existence of many local error minima in parameter space, traditional error mapping or steepest descent search algorithms are not suitable to optimize the GMD. The focus of the present study is on establishing genetic optimization techniques as a feasible and economical way to optimize the free parameters in the GMD. The behavior of the GMD with optimized parameters is outside the scope of this study, and is discussed in detail in the companion paper.

  16. A comparison of shock-cloud and wind-cloud interactions: effect of increased cloud density contrast on cloud evolution

    Science.gov (United States)

    Goldsmith, K. J. A.; Pittard, J. M.

    2018-05-01

    The similarities, or otherwise, of a shock or wind interacting with a cloud of density contrast χ = 10 were explored in a previous paper. Here, we investigate such interactions with clouds of higher density contrast. We compare the adiabatic hydrodynamic interaction of a Mach 10 shock with a spherical cloud of χ = 103 with that of a cloud embedded in a wind with identical parameters to the post-shock flow. We find that initially there are only minor morphological differences between the shock-cloud and wind-cloud interactions, compared to when χ = 10. However, once the transmitted shock exits the cloud, the development of a turbulent wake and fragmentation of the cloud differs between the two simulations. On increasing the wind Mach number, we note the development of a thin, smooth tail of cloud material, which is then disrupted by the fragmentation of the cloud core and subsequent `mass-loading' of the flow. We find that the normalized cloud mixing time (tmix) is shorter at higher χ. However, a strong Mach number dependence on tmix and the normalized cloud drag time, t_{drag}^' }, is not observed. Mach-number-dependent values of tmix and t_{drag}^' } from comparable shock-cloud interactions converge towards the Mach-number-independent time-scales of the wind-cloud simulations. We find that high χ clouds can be accelerated up to 80-90 per cent of the wind velocity and travel large distances before being significantly mixed. However, complete mixing is not achieved in our simulations and at late times the flow remains perturbed.

  17. Fluid-structure interaction simulation of floating structures interacting with complex, large-scale ocean waves and atmospheric turbulence with application to floating offshore wind turbines

    Science.gov (United States)

    Calderer, Antoni; Guo, Xin; Shen, Lian; Sotiropoulos, Fotis

    2018-02-01

    We develop a numerical method for simulating coupled interactions of complex floating structures with large-scale ocean waves and atmospheric turbulence. We employ an efficient large-scale model to develop offshore wind and wave environmental conditions, which are then incorporated into a high resolution two-phase flow solver with fluid-structure interaction (FSI). The large-scale wind-wave interaction model is based on a two-fluid dynamically-coupled approach that employs a high-order spectral method for simulating the water motion and a viscous solver with undulatory boundaries for the air motion. The two-phase flow FSI solver is based on the level set method and is capable of simulating the coupled dynamic interaction of arbitrarily complex bodies with airflow and waves. The large-scale wave field solver is coupled with the near-field FSI solver with a one-way coupling approach by feeding into the latter waves via a pressure-forcing method combined with the level set method. We validate the model for both simple wave trains and three-dimensional directional waves and compare the results with experimental and theoretical solutions. Finally, we demonstrate the capabilities of the new computational framework by carrying out large-eddy simulation of a floating offshore wind turbine interacting with realistic ocean wind and waves.

  18. Polar summer mesospheric extreme horizontal drift speeds during interplanetary corotating interaction regions (CIRs) and high-speed solar wind streams: Coupling between the solar wind and the mesosphere

    Science.gov (United States)

    Lee, Young-Sook; Kirkwood, Sheila; Kwak, Young-Sil; Kim, Kyung-Chan; Shepherd, Gordon G.

    2014-05-01

    We report the observation of echo extreme horizontal drift speed (EEHS, ≥ 300 m s-1) during polar mesospheric (80-90 km) summer echoes (PMSEs) by the VHF (52 MHz) radar at Esrange, Sweden, in years of 2006 and 2008. The EEHS occur in PMSEs as correlated with high-speed solar wind streams (HSSs), observed at least once in 12-17% of all hours of observation for the two summers. The EEHS rate peaks occur either during high solar wind speed in the early part of the PMSE season or during the arrival of interplanetary corotating interaction regions (CIRs) followed by peaks in PMSE occurrence rate after 1-4 days, in the latter part of the 2006 summer. The cause of EEHS rate peaks is likely under the competition between the interval of the CIR and HSS passage over the magnetosphere. A candidate process in producing EEHS is suggested to be localized strong electric field, which is caused by solar wind energy transfer from the interaction of CIR and HSS with the magnetosphere in a sequential manner. We suggest that EEHS are created by strong electric field, estimated as > 10-30 V m-1 at 85 km altitude, exceeding the mesospheric breakdown threshold field.

  19. Raindrop and flow interactions for interrill erosion with wind-driven rain

    NARCIS (Netherlands)

    Erpul, G.; Gabriels, D.; Darell Norton, L.; Dennis, C.; Huang, C.H.; Visser, S.M.

    2013-01-01

    Wind-driven rain (WDR) experiments were conducted to evaluate the interrill component of the Water Erosion Prediction Project model with a two-dimensional experimental set-up in a wind tunnel. Synchronized wind and rain simulations were applied to soil surfaces on windward and leeward slopes of 7,

  20. Interaction of additive noise and nonlinear dynamics in the double-gyre wind-driven ocean circulation

    NARCIS (Netherlands)

    Sapsis, T.; Dijkstra, H.A.

    2013-01-01

    In this paper the authors study the interactions of additive noise and nonlinear dynamics in a quasi-geostrophicmodel of the double-gyre wind-driven ocean circulation. The recently developed framework of dynamically orthogonal field theory is used to determine the statistics of the flows that arise

  1. Eyes in the sky. Interactions between asymptotic giant branch star winds and the interstellar magnetic field

    Science.gov (United States)

    van Marle, A. J.; Cox, N. L. J.; Decin, L.

    2014-10-01

    Context. The extended circumstellar envelopes (CSEs) of evolved low-mass stars display a large variety of morphologies. Understanding the various mechanisms that give rise to these extended structures is important to trace their mass-loss history. Aims: Here, we aim to examine the role of the interstellar magnetic field in shaping the extended morphologies of slow dusty winds of asymptotic giant branch (AGB) stars in an effort to pin-point the origin of so-called eye shaped CSEs of three carbon-rich AGB stars. In addition, we seek to understand if this pre-planetary nebula (PN) shaping can be responsible for asymmetries observed in PNe. Methods: Hydrodynamical simulations are used to study the effect of typical interstellar magnetic fields on the free-expanding spherical stellar winds as they sweep up the local interstellar medium (ISM). Results: The simulations show that typical Galactic interstellar magnetic fields of 5 to 10 μG are sufficient to alter the spherical expanding shells of AGB stars to appear as the characteristic eye shape revealed by far-infrared observations. The typical sizes of the simulated eyes are in accordance with the observed physical sizes. However, the eye shapes are transient in nature. Depending on the stellar and interstellar conditions, they develop after 20 000 to 200 000 yrs and last for about 50 000 to 500 000 yrs, assuming that the star is at rest relative to the local interstellar medium. Once formed, the eye shape develops lateral outflows parallel to the magnetic field. The explosion of a PN in the centre of the eye-shaped dust shell gives rise to an asymmetrical nebula with prominent inward pointing Rayleigh-Taylor instabilities. Conclusions: Interstellar magnetic fields can clearly affect the shaping of wind-ISM interaction shells. The occurrence of the eyes is most strongly influenced by stellar space motion and ISM density. Observability of this transient phase is favoured for lines-of-sight perpendicular to the

  2. Laboratory Simulations of CME-Solar Wind Interactions Using a Coaxial Gun and Background Plasma

    Science.gov (United States)

    Wallace, B. H.; Zhang, Y.; Fisher, D.; Gilmore, M.

    2016-12-01

    Understanding and predicting solar coronal mass ejections (CMEs) is of critical importance for mitigating their disruptive behavior on ground- and space-based technologies. While predictive models of CME propagation and evolution have relied primarily on sparse in-situ data along with ground and satellite images for validation purposes, emerging laboratory efforts have shown that CME-like events can be created with parameters applicable to the solar regime that may likewise aid in predictive modeling. A modified version of the coaxial plasma gun from the Plasma Bubble Expansion Experiment (PBEX) [A. G. Lynn, Y. Zhang, S. C. Hsu, H. Li, W. Liu, M. Gilmore, and C. Watts, Bull. Amer. Phys. Soc. 52, 53 (2007)] will be used in conjunction with the Helicon-Cathode (HelCat) basic plasma science device in order to observe the magnetic characteristics of CMEs as they propagate through the solar wind. The evolution of these interactions will be analyzed using a multi-tip Langmuir probe array, a 33-position B-dot probe array, and a high speed camera. The results of this investigation will be used alongside the University of Michigan's BATS-R-US 3-D MHD numerical code, which will be used to perform simulations of the coaxial plasma gun experiment. The results of these two approaches will be compared in order to validate the capabilities of the BATS-R-US code as well as to further our understanding of magnetic reconnection and other processes that take place as CMEs propagate through the solar wind. The details of the experimental setup as well as the analytical approach are discussed.

  3. Insights into Airframe Aerodynamics and Rotor-on-Wing Interactions from a 0.25-Scale Tiltrotor Wind Tunnel Model

    Science.gov (United States)

    Young, L. A.; Lillie, D.; McCluer, M.; Yamauchi, G. K.; Derby, M. R.

    2001-01-01

    A recent experimental investigation into tiltrotor aerodynamics and acoustics has resulted in the acquisition of a set of data related to tiltrotor airframe aerodynamics and rotor and wing interactional aerodynamics. This work was conducted in the National Full-scale Aerodynamics Complex's (NFAC) 40-by-80 Foot Wind Tunnel, at NASA Ames Research Center, on the Full-Span Tilt Rotor Aeroacoustic Model (TRAM). The full-span TRAM wind tunnel test stand is nominally based on a quarter-scale representation of the V-22 aircraft. The data acquired will enable the refinement of analytical tools for the prediction of tiltrotor aeromechanics and aeroacoustics.

  4. Plasma turbulence resulting from the interaction between the solar wind and the earth's magnetic field

    International Nuclear Information System (INIS)

    Roux, A.

    1989-01-01

    The interaction between the supersonic and super-Alfvenic solar wind plasma and the Earth's magnetic field leads to the formation of critical layers, such as the bow shock, the magnetopause, the polar cusp, and the inner and outer edge of the plasmasheet. The mean free path between binary colisions being much larger than the transverse scale of these layers, plasma turbulence must ensure the thermalization, the magnetic diffusion, the dissipation within these critical layers. We suggest the existence of small scale, presumably 2D structures, developing within these thin layers. The unambiguous characterization of these small-scale structures is, however, beyond the capabilities of existing spacecraft, which cannot spatially resolve them, nor disentangle spatial/temporal variations. We present a new mission concept: a cluster of four relatively simple spacecraft, which will make it possible (i) to disentangle spatial from temporal variations, (ii) to evaluate, by finite differences between spacecraft measurements, the gradients, divergences, curls of MHD parameters, and )iii) to characterize small-scale structures, via inter-spacecraft correlations. (author). 10 refs.; 10 figs

  5. Wild Steelhead and introduced spring Chinook Salmon in the Wind River, Washington: Overlapping populations and interactions

    Science.gov (United States)

    Jezorek, I.G.; Connolly, P.J.

    2010-01-01

    We investigated interactions of introduced juvenile spring Chinook salmon Oncorhynchus tshawytscha with wild juvenile steelhead O. mykiss in the upper Wind River watershed (rkm 24.6 to rkm 43.8), Washington. Our objective was to determine if the presence of introduced spring Chinook salmon influenced populations of wild juvenile steelhead and if other biotic or abiotic factors influenced distribution and populations of these species. We snorkeled to assess distribution and abundance in one to six stream reaches per year during 2001 through 2007. Juvenile steelhead were found in each sampled reach each year, but juvenile Chinook salmon were not. The upstream extent of distribution of juvenile Chinook salmon varied from rkm 29.7 to 42.5. Our analyses suggest that juvenile Chinook salmon distribution was much influenced by flow during the spawning season. Low flow appeared to limit access of escaped adult Chinook salmon to upper stream reaches. Abundance of juvenile Chinook salmon was also influenced by base flow during the previous year, with base flow occurring post spawn in late August or early September. There were no relationships between juvenile Chinook salmon abundance and number of Chinook salmon spawners, magnitude of winter flow that might scour redds, or abundance of juvenile steelhead. Abundance of age-0 steelhead was influenced primarily by the number of steelhead spawners the previous year, and abundance of age-1 steelhead was influenced primarily by abundance of age-0 steelhead the previous year. Juvenile steelhead abundance did not show a relationship with base or peak flows, nor with number of escaped Chinook salmon adults during the previous year. We did not detect a negative influence of the relatively low abundance of progeny of escaped Chinook salmon on juvenile steelhead abundance. This low abundance of juvenile Chinook salmon was persistent throughout our study and is likely a result of hatchery management and habitat conditions. Should one or

  6. Numerical simulation of wave-current interaction under strong wind conditions

    Science.gov (United States)

    Larrañaga, Marco; Osuna, Pedro; Ocampo-Torres, Francisco Javier

    2017-04-01

    Although ocean surface waves are known to play an important role in the momentum and other scalar transfer between the atmosphere and the ocean, most operational numerical models do not explicitly include the terms of wave-current interaction. In this work, a numerical analysis about the relative importance of the processes associated with the wave-current interaction under strong off-shore wind conditions in Gulf of Tehuantepec (the southern Mexican Pacific) was carried out. The numerical system includes the spectral wave model WAM and the 3D hydrodynamic model POLCOMS, with the vertical turbulent mixing parametrized by the kappa-epsilon closure model. The coupling methodology is based on the vortex-force formalism. The hydrodynamic model was forced at the open boundaries using the HYCOM database and the wave model was forced at the open boundaries by remote waves from the southern Pacific. The atmospheric forcing for both models was provided by a local implementation of the WRF model, forced at the open boundaries using the CFSR database. The preliminary analysis of the model results indicates an effect of currents on the propagation of the swell throughout the study area. The Stokes-Coriolis term have an impact on the transient Ekman transport by modifying the Ekman spiral, while the Stokes drift has an effect on the momentum advection and the production of TKE, where the later induces a deepening of the mixing layer. This study is carried out in the framework of the project CONACYT CB-2015-01 255377 and RugDiSMar Project (CONACYT 155793).

  7. Real-time 3-D hybrid simulation of Titan's plasma interaction during a solar wind excursion

    Directory of Open Access Journals (Sweden)

    S. Simon

    2009-09-01

    Full Text Available The plasma environment of Saturn's largest satellite Titan is known to be highly variable. Since Titan's orbit is located within the outer magnetosphere of Saturn, the moon can leave the region dominated by the magnetic field of its parent body in times of high solar wind dynamic pressure and interact with the thermalized magnetosheath plasma or even with the unshocked solar wind. By applying a three-dimensional hybrid simulation code (kinetic description of ions, fluid electrons, we study in real-time the transition that Titan's plasma environment undergoes when the moon leaves Saturn's magnetosphere and enters the supermagnetosonic solar wind. In the simulation, the transition between both plasma regimes is mimicked by a reversal of the magnetic field direction as well as a change in the composition and temperature of the impinging plasma flow. When the satellite enters the solar wind, the magnetic draping pattern in its vicinity is reconfigured due to reconnection, with the characteristic time scale of this process being determined by the convection of the field lines in the undisturbed plasma flow at the flanks of the interaction region. The build-up of a bow shock ahead of Titan takes place on a typical time scale of a few minutes as well. We also analyze the erosion of the newly formed shock front upstream of Titan that commences when the moon re-enters the submagnetosonic plasma regime of Saturn's magnetosphere. Although the model presented here is far from governing the full complexity of Titan's plasma interaction during a solar wind excursion, the simulation provides important insights into general plasma-physical processes associated with such a disruptive change of the upstream flow conditions.

  8. Heat plan Denmark 2010. Appendix report; Varmeplan Danmark 2010. Bilagsrapport

    Energy Technology Data Exchange (ETDEWEB)

    Dyrelund, A.; Fafner, K.; Ulbjerg, F. (and others)

    2010-09-15

    Heat Plan Denmark 2010 is an update of Heat Plan Denmark 2008 and confirms how the sector has reduced the CO{sub 2} emission in Denmark since 1980 and how this development can continue in a cost effective way to an almost CO{sub 2} neutral heating sector in 2030. The study is based on an overall least cost evaluation of the best existing technology taking into account the interaction between buildings, district heating and the power system with a large share of wind energy. The present appendix report contains the technical and economical documentation for the main report. (ln)

  9. Wind tunnel study of the wind turbine interaction with a boundary-layer flow: Upwind region, turbine performance, and wake region

    Science.gov (United States)

    Bastankhah, M.; Porté-Agel, F.

    2017-06-01

    Comprehensive wind tunnel experiments were carried out to study the interaction of a turbulent boundary layer with a wind turbine operating under different tip-speed ratios and yaw angles. Force and power measurements were performed to characterize the variation of thrust force (both magnitude and direction) and generated power of the wind turbine under different operating conditions. Moreover, flow measurements, collected using high-resolution particle-image velocimetry as well as hot-wire anemometry, were employed to systematically study the flow in the upwind, near-wake, and far-wake regions. These measurements provide new insights into the effect of turbine operating conditions on flow characteristics in these regions. For the upwind region, the results show a strong lateral asymmetry under yawed conditions. For the near-wake region, the evolution of tip and root vortices was studied with the use of both instantaneous and phase-averaged vorticity fields. The results suggest that the vortex breakdown position cannot be determined based on phase-averaged statistics, particularly for tip vortices under turbulent inflow conditions. Moreover, the measurements in the near-wake region indicate a complex velocity distribution with a speed-up region in the wake center, especially for higher tip-speed ratios. In order to elucidate the meandering tendency of far wakes, particular focus was placed on studying the characteristics of large turbulent structures in the boundary layer and their interaction with wind turbines. Although these structures are elongated in the streamwise direction, their cross sections are found to have a size comparable to the rotor area, so that they can be affected by the presence of the turbine. In addition, the study of spatial coherence in turbine wakes reveals that any statistics based on streamwise velocity fluctuations cannot provide reliable information about the size of large turbulent structures in turbine wakes due to the effect of wake

  10. On the interaction of wind and steep gravity wave groups using Miles' and Jeffreys' mechanisms

    Directory of Open Access Journals (Sweden)

    J. Touboul

    2008-12-01

    Full Text Available The interaction of wind and water wave groups is investigated theoretically and numerically. A steep wave train is generated by means of dispersive focusing, using both the linear theory and fully nonlinear equations. The linear theory is based on the Schrödinger equation while the nonlinear approach is developed numerically within the framework of the potential theory. The interaction between the chirped wave packet and wind is described by the Miles' mechanism. The differences between both approaches are discussed, and the influence of nonlinearity is emphasized. Furthermore, a different mechanism is considered, described by the modified Jeffreys' sheltering theory. From comparison between the two mechanisms, it is found that the persistence of the steep wave group depends on the physical model used, and is significantly increased when we use the latter mechanism.

  11. Effects of soil–structure interaction on real time dynamic response of offshore wind turbines on monopiles

    DEFF Research Database (Denmark)

    Damgaard, M.; Zania, Varvara; Andersen, L.V.

    2014-01-01

    , a computationally efficient modelling approach of including the dynamic soil–structure interaction into aeroelastic codes is presented with focus on monopile foundations. Semi-analytical frequency-domain solutions are applied to evaluate the dynamic impedance functions of the soil–pile system at a number...... normal operating mode. The aeroelastic response is evaluated for three different foundation conditions, i.e. apparent fixity length, the consistent lumped-parameter model and fixed support at the seabed. The effect of soil–structure interaction is shown to be critical for the design, estimated in terms......Offshore wind turbines are highly dynamically loaded structures, their response being dominated by the interrelation effects between the turbine and the support structure. Since the dynamic response of wind turbine structures occurs in a frequency range close to the excitation frequencies related...

  12. Acoustic measurements from a rotor blade-vortex interaction noise experiment in the German-Dutch Wind Tunnel (DNW)

    Science.gov (United States)

    Martin, Ruth M.; Splettstoesser, W. R.; Elliott, J. W.; Schultz, K.-J.

    1988-01-01

    Acoustic data are presented from a 40 percent scale model of the 4-bladed BO-105 helicopter main rotor, measured in the large European aeroacoustic wind tunnel, the DNW. Rotor blade-vortex interaction (BVI) noise data in the low speed flight range were acquired using a traversing in-flow microphone array. The experimental apparatus, testing procedures, calibration results, and experimental objectives are fully described. A large representative set of averaged acoustic signals is presented.

  13. Reducing Bat Fatalities From Interactions with Operating Wind Turbines (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    Lawson, M.

    2013-11-01

    One of the biggest advantages of wind energy is that, overall, it has fewer negative impacts on the environment than fossil fuel-generated energy. Most professionals in the wind industry would like to reduce the impact of energy generation on plants, animals, and their habitats. This is why the industry is highly motivated to find out why migrating bats have unexpectedly high fatality rates near operating wind farms. New research has provided quantitative data that indicates barotrauma is not a major cause of bat deaths around operating turbines.

  14. LCT-coil design: Mechanical interaction between composite winding and steel casing under various test conditions

    International Nuclear Information System (INIS)

    Dolensky, B.; Messemer, G.; Zehlein, H.; Erb, J.

    1981-01-01

    Finite element computations for the structural design of the large superconducting toroidal field coil contributed by EURATOM to the Large Coil Test Facility (LCTF) at ORNL, USA were performed at KfK, using the ASKA code. The layout of the coil must consider different types of requirements: firstly, an optimal D-shaped contour minimizing circumferential stress gradients under normal operation in the toroidal arrangement must be defined. Secondly, the three-dimensional real design effects due to the actual support conditions, manufacturing tolerances etc. must be mastered for different basic operational and failure load cases. And, thirdly, the design must stand a single coil qualification test in the TOSKA-facility at KfK, Karlsruhe, FRG, before it is plugged into the LCTF. The emphasis of the paper is three-pronged according to these requirements: i) the 3D magnetic body forces as well as the underlying magnetic fields as computed by the HEDO-code are described. ii) The mechanical interaction between casing and winding as given elsewhere in terms of high stress regions, gaps, slide movements and contact forces for various load cases representing the LCTF test conditions is illustrated here by a juxtaposition of the operational deformations and stresses within the LCTF and the TOSKA. iii) Particular effects like the restraint imposed by a corset-type reinforcement of the coil in the TOSKA test facility to limit the breathing deformation are parametrically studied. Moreover, the possibilities to derive scaling laws which make essential results transferable to larger coils by extracting a 1D mechanical response from the 3D finite element model is also demonstrated. (orig./GG)

  15. Assessment of natural frequency of installed offshore wind turbines using nonlinear finite element model considering soil-monopile interaction

    Directory of Open Access Journals (Sweden)

    Djillali Amar Bouzid

    2018-04-01

    Full Text Available A nonlinear finite element model is developed to examine the lateral behaviors of monopiles, which support offshore wind turbines (OWTs chosen from five different offshore wind farms in Europe. The simulation is using this model to accurately estimate the natural frequency of these slender structures, as a function of the interaction of the foundations with the subsoil. After a brief introduction to the wind power energy as a reliable alternative in comparison to fossil fuel, the paper focuses on concept of natural frequency as a primary indicator in designing the foundations of OWTs. Then the range of natural frequencies is provided for a safe design purpose. Next, an analytical expression of an OWT natural frequency is presented as a function of soil-monopile interaction through monopile head springs characterized by lateral stiffness KL, rotational stiffness KR and cross-coupling stiffness KLR, of which the differences are discussed. The nonlinear pseudo three-dimensional finite element vertical slices model has been used to analyze the lateral behaviors of monopiles supporting the OWTs of different wind farm sites considered. Through the monopiles head movements (displacements and rotations, the values of KL, KR and KLR were obtained and substituted in the analytical expression of natural frequency for comparison. The comparison results between computed and measured natural frequencies showed an excellent agreement for most cases. This confirms the convenience of the finite element model used for the accurate estimation of the monopile head stiffness. Keywords: Nonlinear finite element analysis, Vertical slices model, Monopiles under horizontal loading, Natural frequency, Monopile head stiffness, Offshore wind turbines (OWTs

  16. Mitigation of Wind Turbine/Vortex Interaction Using Disturbance Accommodating Control

    Energy Technology Data Exchange (ETDEWEB)

    Hand, M. M.

    2003-12-01

    Wind turbines, a competitive source of emission-free electricity, are being designed with diameters and hub heights approaching 100 m, to further reduce the cost of the energy they produce. At this height above the ground, the wind turbine is exposed to atmospheric phenomena such as low-level jets, gravity waves, and Kelvin-Helmholtz instabilities, which are not currently modeled in wind turbine design codes. These atmospheric phenomena can generate coherent turbulence that causes high cyclic loads on wind turbine blades. These fluctuating loads lead to fatigue damage accumulation and blade lifetime reduction. Advanced control was used to mitigate vortex-induced blade cyclic loading. A full-state feedback controller that incorporates more detailed vortex inputs achieved significantly greater blade load reduction. Blade loads attributed to vortex passage, then, can be reduced through advanced control, and further reductions appear feasible.

  17. Wind Tunnel Model Design for Sonic Boom Studies of Nozzle Jet with Shock Interactions

    Science.gov (United States)

    Cliff, Susan E.; Denison, Marie; Sozer, Emre; Moini-Yekta, Shayan

    2016-01-01

    NASA and Industry are performing vehicle studies of configurations with low sonic boom pressure signatures. The computational analyses of modern configuration designs have matured to the point where there is confidence in the prediction of the pressure signature from the front of the vehicle, but uncertainty in the aft signatures with often greater boundary layer effects and nozzle jet pressures. Wind tunnel testing at significantly lower Reynolds numbers than in flight and without inlet and nozzle jet pressures make it difficult to accurately assess the computational solutions of flight vehicles. A wind tunnel test in the NASA Ames 9- by 7-Foot Supersonic Wind Tunnel from Mach 1.6 to 2.0 will be used to assess the effects of shocks from components passing through nozzle jet plumes on the sonic boom pressure signature and provide datasets for comparison with CFD codes. A large number of high-fidelity numerical simulations of wind tunnel test models with a variety of shock generators that simulate horizontal tails and aft decks have been studied to provide suitable models for sonic boom pressure measurements using a minimally intrusive pressure rail in the wind tunnel. The computational results are presented and the evolution of candidate wind tunnel models is summarized and discussed in this paper.

  18. Raptor interactions with wind energy: Case studies from around the world

    Science.gov (United States)

    Watson, Richard T.; Kolar, Patrick S.; Ferrer, Miguel; Nygård, Torgeir; Johnston, Naira; Hunt, W. Grainger; Smit-Robinson, Hanneline A.; Farmer, Christopher J; Huso, Manuela; Katzner, Todd

    2018-01-01

    The global potential for wind power generation is vast, and the number of installations is increasing rapidly. We review case studies from around the world of the effects on raptors of wind-energy development. Collision mortality, displacement, and habitat loss have the potential to cause population-level effects, especially for species that are rare or endangered. The impact on raptors has much to do with their behavior, so careful siting of wind-energy developments to avoid areas suited to raptor breeding, foraging, or migration would reduce these effects. At established wind farms that already conflict with raptors, reduction of fatalities may be feasible by curtailment of turbines as raptors approach, and offset through mitigation of other human causes of mortality such as electrocution and poisoning, provided the relative effects can be quantified. Measurement of raptor mortality at wind farms is the subject of intense effort and study, especially where mitigation is required by law, with novel statistical approaches recently made available to improve the notoriously difficult-to-estimate mortality rates of rare and hard-to-detect species. Global standards for wind farm placement, monitoring, and effects mitigation would be a valuable contribution to raptor conservation worldwide.

  19. THE INTERACTION OF VENUS-LIKE, M-DWARF PLANETS WITH THE STELLAR WIND OF THEIR HOST STAR

    International Nuclear Information System (INIS)

    Cohen, O.; Drake, J. J.; Garraffo, C.; Ma, Y.; Glocer, A.; Bell, J. M.; Gombosi, T. I.

    2015-01-01

    We study the interaction between the atmospheres of Venus-like, non-magnetized exoplanets orbiting an M-dwarf star, and the stellar wind using a multi-species MHD model. We focus our investigation on the effect of enhanced stellar wind and enhanced EUV flux as the planetary distance from the star decreases. Our simulations reveal different topologies of the planetary space environment for sub- and super-Alfvénic stellar wind conditions, which could lead to dynamic energy deposition into the atmosphere during the transition along the planetary orbit. We find that the stellar wind penetration for non-magnetized planets is very deep, up to a few hundreds of kilometers. We estimate a lower limit for the atmospheric mass-loss rate and find that it is insignificant over the lifetime of the planet. However, we predict that when accounting for atmospheric ion acceleration, a significant amount of the planetary atmosphere could be eroded over the course of a billion years

  20. The interaction between the solar wind and the heterogeneous neutral gas coma of comet 67P/Churyumov-Gerasimenko

    Science.gov (United States)

    Rubin, Martin; Toth, Gabor; Tenishev, Valeriy; Fougere, Nicolas; Huang, Zhenguang

    2016-07-01

    Comets are surrounded by an extended gas and dust coma. Neutral particles are continuously ionized by solar irradiation and then picked-up by the solar wind. This leads to a complex interaction between the neutral gas coma and the solar wind, which changes over the course of the comet's orbit around the Sun. The European Space Agency's Rosetta spacecraft has been in orbit around comet 67P/Churyumov-Gerasimenko since August 2014. Rosetta carries several instruments to investigate the comet's nucleus and surrounding neutral gas coma and plasma. Part of the payload is the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) that consists of two mass spectrometers and a pressure sensor. ROSINA was designed to measure the neutral gas abundance and composition and low energy ions in the coma in situ. ROSINA observations have shown that the coma is very heterogeneous both in total density and composition of the neutral gas. This heterogeneity is driven in large part by the complex shape of the nucleus and the varying illumination conditions associated with the comet's rotation. In this presentation we will show the time-dependent distribution of the major volatiles around the comet constrained by ROSINA observations. Furthermore we will investigate the impact of the highly non-symmetric neutral gas coma on the interaction of the solar wind with the comet.

  1. Cumulative impact assessments and bird/wind farm interactions: Developing a conceptual framework

    International Nuclear Information System (INIS)

    Masden, Elizabeth A.; Fox, Anthony D.; Furness, Robert W.; Bullman, Rhys; Haydon, Daniel T.

    2010-01-01

    The wind power industry has grown rapidly in the UK to meet EU targets of sourcing 20% of energy from renewable sources by 2020. Although wind power is a renewable energy source, there are environmental concerns over increasing numbers of wind farm proposals and associated cumulative impacts. Individually, a wind farm, or indeed any action, may have minor effects on the environment, but collectively these may be significant, potentially greater than the sum of the individual parts acting alone. EU and UK legislation requires a cumulative impact assessment (CIA) as part of Environmental Impact Assessments (EIA). However, in the absence of detailed guidance and definitions, such assessments within EIA are rarely adequate, restricting the acquisition of basic knowledge about the cumulative impacts of wind farms on bird populations. Here we propose a conceptual framework to promote transparency in CIA through the explicit definition of impacts, actions and scales within an assessment. Our framework requires improved legislative guidance on the actions to include in assessments, and advice on the appropriate baselines against which to assess impacts. Cumulative impacts are currently considered on restricted scales (spatial and temporal) relating to individual development EIAs. We propose that benefits would be gained from elevating CIA to a strategic level, as a component of spatially explicit planning.

  2. Surface melt on Antarctic ice shelves driven by wind-albedo interactions

    Science.gov (United States)

    Lhermitte, Stef; Lenaerts, Jan

    2017-04-01

    Surface melt and subsequent firn air depletion is considered an important precursor for disintegration of Antarctic ice shelves, causing grounded glaciers to accelerate and sea level to rise. Recent studies have highlighted the impact of surface winds on Antarctic ice shelf melt, both on the Antarctic Peninsula and in East Antarctica. In the Antarctic Peninsula, foehn winds enhance melting near the grounding line, which in the recent past has led to the disintegration of the most northerly ice shelves. On the East Antarctic ice shelves, on the other hand, meltwater-induced firn air depletion is found in the grounding zone as result of persistent katabatic winds, regionally warming the atmosphere and inducing a melt-albedo feedback. Here, we use a combination multi-source satellite imagery, snow modelling, climate model output and in-situ observations to highlight the importance of this wind-induced melt and to show its widespread occurrence across Antarctica. The satellite imagery gives insight in the meltwater drainage systems, showing spatio-temporal changes in both supraglacial and englacial water throughout the melt season and during the subsequent winter. Although the wind-induced melt is a regional phenomenon with strong inter-annual variability, it is strongly correlated to larger scale climate parameters, such as summer surface temperature. Based on these correlations and snow model output driven by future climate scenarios, we can constrain the future changes to this local melt near the grounding line.

  3. An interactive graphics program to retrieve, display, compare, manipulate, curve fit, difference and cross plot wind tunnel data

    Science.gov (United States)

    Elliott, R. D.; Werner, N. M.; Baker, W. M.

    1975-01-01

    The Aerodynamic Data Analysis and Integration System (ADAIS), developed as a highly interactive computer graphics program capable of manipulating large quantities of data such that addressable elements of a data base can be called up for graphic display, compared, curve fit, stored, retrieved, differenced, etc., was described. The general nature of the system is evidenced by the fact that limited usage has already occurred with data bases consisting of thermodynamic, basic loads, and flight dynamics data. Productivity using ADAIS of five times that for conventional manual methods of wind tunnel data analysis is routinely achieved. In wind tunnel data analysis, data from one or more runs of a particular test may be called up and displayed along with data from one or more runs of a different test. Curves may be faired through the data points by any of four methods, including cubic spline and least squares polynomial fit up to seventh order.

  4. Superluminous Transients at AGN Centers from Interaction between Black Hole Disk Winds and Broad-line Region Clouds

    Energy Technology Data Exchange (ETDEWEB)

    Moriya, Takashi J.; Tanaka, Masaomi; Ohsuga, Ken [Division of Theoretical Astronomy, National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Morokuma, Tomoki, E-mail: takashi.moriya@nao.ac.jp [Institute of Astronomy, Graduate School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan)

    2017-07-10

    We propose that superluminous transients that appear at central regions of active galactic nuclei (AGNs) such as CSS100217:102913+404220 (CSS100217) and PS16dtm, which reach near- or super-Eddington luminosities of the central black holes, are powered by the interaction between accretion-disk winds and clouds in broad-line regions (BLRs) surrounding them. If the disk luminosity temporarily increases by, e.g., limit–cycle oscillations, leading to a powerful radiatively driven wind, strong shock waves propagate in the BLR. Because the dense clouds in the AGN BLRs typically have similar densities to those found in SNe IIn, strong radiative shocks emerge and efficiently convert the ejecta kinetic energy to radiation. As a result, transients similar to SNe IIn can be observed at AGN central regions. Since a typical black hole disk-wind velocity is ≃0.1 c , where c is the speed of light, the ejecta kinetic energy is expected to be ≃10{sup 52} erg when ≃1 M {sub ⊙} is ejected. This kinetic energy is transformed to radiation energy in a timescale for the wind to sweep up a similar mass to itself in the BLR, which is a few hundred days. Therefore, both luminosities (∼10{sup 44} erg s{sup −1}) and timescales (∼100 days) of the superluminous transients from AGN central regions match those expected in our interaction model. If CSS100217 and PS16dtm are related to the AGN activities triggered by limit–cycle oscillations, they become bright again in coming years or decades.

  5. Mitigation of wind turbine/vortex interaction using disturbance accommodating control

    Science.gov (United States)

    Hand, M. Maureen

    Wind turbines, a competitive source of emission-free electricity, are being designed with diameters and hub heights approaching 100 m, to further reduce the cost of the energy they produce. At this height above the ground, the wind turbine is exposed to atmospheric phenomena such as low-level jets, gravity waves, and Kelvin-Helmholtz instabilities, which are not currently modeled in wind turbine design codes. These atmospheric phenomena can generate coherent turbulence that causes high cyclic loads on wind turbine blades. These fluctuating loads lead to fatigue damage accumulation and blade lifetime reduction. The National Renewable Energy Laboratory (NREL) conducted an experiment to record wind turbine load response and inflow measurements. The spatial resolution of the inflow measurements was insufficient to identify specific turbulence characteristics that contribute to high cyclic loads. However, strong evidence supported the hypothesis that coherent vorticity passage through the rotor was directly correlated with large blade cyclic amplitudes. An analytic Rankine vortex model was created and implemented in wind turbine simulation codes to isolate the aerodynamic response of the wind turbine to inflow vortices. Numerous simulations computed the blade load cyclic response to vortices of varying radius, circulation strength, orientation, location with respect to the hub, and plane of rotation. The vortex in the plane of rotation most likely to occur as a result of Kelvin-Helmholtz instabilities produces the highest cyclic amplitudes. The response is similar for two- and three-blade wind turbines. Advanced control was used to mitigate vortex-induced blade cyclic loading. The MATLAB(c) with Simulink(c) computational environment was used for control design. Disturbance Accommodating Control (DAC) was used to cancel the vortex "disturbance." Compared to a standard proportional-integral controller, the DAC controller reduced the blade fatigue load for vortices of

  6. Wind turbine inverter robust loop-shaping control subject to grid interaction effects

    DEFF Research Database (Denmark)

    Gryning, Mikkel Peter Sidoroff; Wu, Qiuwei; Blanke, Mogens

    2015-01-01

    the grid and the number of wind turbines connected. Power converter based turbines inject harmonic currents, which are attenuated by passive filters. A robust high order active filter controller is proposed to complement the passive filtering. The H∞ design of the control loop enables desired tracking......An H∞ robust control of wind turbine inverters employing an LCL filter is proposed in this paper. The controller dynamics are designed for selective harmonic filtering in an offshore transmission network subject to parameter perturbations. Parameter uncertainty in the network originates from...

  7. The Local ISM and its Interaction with the Winds of Nearby Late-type Stars

    Science.gov (United States)

    Wood, Brian E.; Linsky, Jeffrey L.

    1998-01-01

    We present new Goddard High-Resolution Spectrograph (GHRS) observations of the Ly-alpha and Mg II absorption lines seen toward the nearby stars 61 Cyg A and 40 Eri A. We use these data to measure interstellar properties along these lines of sight and to search for evidence of circumstellar hydrogen walls, which are produced by collisions between the stellar winds and the Local InterStellar Medium (LISM). We were able to model the Ly-alpha lines of both stars without hydrogen-wall absorption components, but for 61 Cyg A the fit required a stellar Ly-alpha, line profile with an improbably deep self-reversal, and for 40 Eri A the fit required a very low deuterium-to-hydrogen ratio that is inconsistent with previous GHRS measurements. Since these problems could be rectified simply by including stellar hydrogen-wall components with reasonable attributes, our preferred fits to the data include these components. We have explored several ways in which the hydrogen-wall properties measured here and in previous work can be used to study stellar winds and the LISM. We argue that the existence of a hydrogen wall around 40 Eri A and a low H I column density along that line of sight imply that either the interstellar density must decrease toward 40 Eri A or the hydrogen ionization fraction (chi) must increase. We find that hydrogen-wall temperatures are larger for stars with faster velocities through the LISM. The observed temperature-velocity relation is consistent with the predictions of hydromagnetic shock jump conditions. More precise comparison of the data and the jump conditions suggests crude upper limits for both chi and the ratio of magnetic to thermal pressure in the LISM (alpha): chi less than 0.6 and alpha less than 2. The latter upper limit corresponds to a limit on the LISM magnetic field of B less than 5 micro G. These results imply that the plasma Mach number of the interstellar wind flowing into the heliosphere is M(sub A) greater than 1.3, which indicates that

  8. Analysis of a utility-interactive wind-photovoltaic hybrid system with battery storage using neural network

    Science.gov (United States)

    Giraud, Francois

    1999-10-01

    This dissertation investigates the application of neural network theory to the analysis of a 4-kW Utility-interactive Wind-Photovoltaic System (WPS) with battery storage. The hybrid system comprises a 2.5-kW photovoltaic generator and a 1.5-kW wind turbine. The wind power generator produces power at variable speed and variable frequency (VSVF). The wind energy is converted into dc power by a controlled, tree-phase, full-wave, bridge rectifier. The PV power is maximized by a Maximum Power Point Tracker (MPPT), a dc-to-dc chopper, switching at a frequency of 45 kHz. The whole dc power of both subsystems is stored in the battery bank or conditioned by a single-phase self-commutated inverter to be sold to the utility at a predetermined amount. First, the PV is modeled using Artificial Neural Network (ANN). To reduce model uncertainty, the open-circuit voltage VOC and the short-circuit current ISC of the PV are chosen as model input variables of the ANN. These input variables have the advantage of incorporating the effects of the quantifiable and non-quantifiable environmental variants affecting the PV power. Then, a simplified way to predict accurately the dynamic responses of the grid-linked WPS to gusty winds using a Recurrent Neural Network (RNN) is investigated. The RNN is a single-output feedforward backpropagation network with external feedback, which allows past responses to be fed back to the network input. In the third step, a Radial Basis Functions (RBF) Network is used to analyze the effects of clouds on the Utility-Interactive WPS. Using the irradiance as input signal, the network models the effects of random cloud movement on the output current, the output voltage, the output power of the PV system, as well as the electrical output variables of the grid-linked inverter. Fourthly, using RNN, the combined effects of a random cloud and a wind gusts on the system are analyzed. For short period intervals, the wind speed and the solar radiation are considered as

  9. Transient studies in large offshore wind farms, taking into account network/circuit breaker interaction

    DEFF Research Database (Denmark)

    Glasdam, Jacob Bærholm; Bak, Claus Leth; Hjerrild, Jesper

    2011-01-01

    Switching overvoltages (SOV) are considered a possible source of experienced component failures in existing off-shore wind farms (OWFs). The inclusion of sufficiently accurate and validated models of the main components in the OWF in the simulation tool is therefore an important issue in order to...

  10. Conceptions of Tornado Wind Speed and Land Surface Interactions among Undergraduate Students in Nebraska

    Science.gov (United States)

    Van Den Broeke, Matthew S.; Arthurs, Leilani

    2015-01-01

    To ascertain novice conceptions of tornado wind speed and the influence of surface characteristics on tornado occurrence, 613 undergraduate students enrolled in introductory science courses at a large state university in Nebraska were surveyed. Our findings show that students lack understanding of the fundamental concepts that (1) tornadoes are…

  11. Laboratory modelling of the wind-wave interaction with modified PIV-method

    Directory of Open Access Journals (Sweden)

    Sergeev Daniil

    2017-01-01

    Full Text Available Laboratory experiments on studying the structure of the turbulent air boundary layer over waves were carried out at the Wind-Wave Flume of the Large Thermostratified Tank of the Institute of Applied Physics, Russian Academy of Sciences (IAP RAS, in conditions modeling the near water boundary layer of the atmosphere under strong and hurricane winds and the equivalent wind velocities from 10 to 48 m/s at the standard height of 10 m. A modified technique of Particle Image Velocimetry (PIV was used to obtain turbulent pulsation averaged velocity fields of the air flow over the water surface curved by a wave and average profiles of the wind velocity. The main modifications are: 1 the use of high-speed video recording (1000-10000 frames/sec with continuous laser illumination helps to obtain ensemble of the velocity fields in all phases of the wavy surface for subsequent statistical processing; 2 the development and application of special algorithms for obtaining form of the curvilinear wavy surface of the images for the conditions of parasitic images of the particles and the droplets in the air side close to the surface; 3 adaptive cross-correlation image processing to finding the velocity fields on a curved grid, caused by wave boarder; 4 using Hilbert transform to detect the phase of the wave in which the measured velocity field for subsequent appropriate binning within procedure obtaining the average characteristics.

  12. Laboratory modelling of the wind-wave interaction with modified PIV-method

    Science.gov (United States)

    Sergeev, Daniil; Kandaurov, Alexander; Troitskaya, Yuliya; Caulliez, Guillemette; Bopp, Maximilian; Jaehne, Bernd

    Laboratory experiments on studying the structure of the turbulent air boundary layer over waves were carried out at the Wind-Wave Flume of the Large Thermostratified Tank of the Institute of Applied Physics, Russian Academy of Sciences (IAP RAS), in conditions modeling the near water boundary layer of the atmosphere under strong and hurricane winds and the equivalent wind velocities from 10 to 48 m/s at the standard height of 10 m. A modified technique of Particle Image Velocimetry (PIV) was used to obtain turbulent pulsation averaged velocity fields of the air flow over the water surface curved by a wave and average profiles of the wind velocity. The main modifications are: 1) the use of high-speed video recording (1000-10000 frames/sec) with continuous laser illumination helps to obtain ensemble of the velocity fields in all phases of the wavy surface for subsequent statistical processing; 2) the development and application of special algorithms for obtaining form of the curvilinear wavy surface of the images for the conditions of parasitic images of the particles and the droplets in the air side close to the surface; 3) adaptive cross-correlation image processing to finding the velocity fields on a curved grid, caused by wave boarder; 4) using Hilbert transform to detect the phase of the wave in which the measured velocity field for subsequent appropriate binning within procedure obtaining the average characteristics.

  13. DYNAMO: a Mars upper atmosphere package for investigating solar wind interaction and escape processes, and mapping Martian fields

    DEFF Research Database (Denmark)

    Chassefiere, E.; Nagy, A.; Mandea, M.

    2004-01-01

    DYNAMO is a small multi-instrument payload aimed at characterizing current atmospheric escape, which is still poorly constrained, and improving gravity and magnetic field representations, in order to better understand the magnetic, geologic and thermal history of Mars. The internal structure...... of periapsis 170 km), and in a lesser extent 2a, offers an unprecedented opportunity to investigate by in situ probing the chemical and dynamical properties of the deep ionosphere, thermosphere, and the interaction between the atmosphere and the solar wind, and therefore the present atmospheric escape rate...

  14. Compression of Jupiter's magnetosphere by the solar wind: Reexamination via MHD simulation of evolving corotating interaction regions

    International Nuclear Information System (INIS)

    Smith, Z.K.; Dryer, M.; Fillius, R.W.; Smith, E.J.; Wolfe, J.H.

    1981-01-01

    We examine the major changes in the solar wind before, during, and after the Pioneer 10 and 11 encounters with the Jovian magnetosphere during 1973 and 1974, respectively. In an earlier study, Smith et al. (1978) concluded that the Jovian magnetosphere was subjected to large-scale compression during at least three or four intervals during which it appeared that the spacecraft had reentered the solar wind or magnetosheath near 50 R/sub J/ after having first entered the magnetosphere near 100 R/sub J/. They based this suggestion on the observations of the sister spacecraft, which indicated--on the basis of a kinematic translation of corotating interaction regions (CIR's)--that these structures would be expected to arrive at Jupiter at the appropriate beginning of these three intervals. Our reexamination of this suggestion involved the numerical simulation of the multiple CIR evolutions from one spacecraft to the sister spacecraft. This approach, considered to be a major improvement, confirms the suggestion by Smith et al. (1978) that Jupiter's magnetosphere was compressed by interplanetary CIR's during three or four of these events. Our MHD simulation also suggests that Jupiter's magnetosphere reacts to solar wind rarefactions in the opposite way--by expanding. A previously unexplained pair of magnetopause crossings on the Pioneer 11 outbound pass may simply be due to a delayed reexpansion of Jupiter's magnetosphere from a compression that occurred during the inbound pass

  15. Wind for Schools (Poster)

    Energy Technology Data Exchange (ETDEWEB)

    Baring-Gould, I.

    2010-05-01

    As the United States dramatically expands wind energy deployment, the industry is challenged with developing a skilled workforce and addressing public resistance. Wind Powering America's Wind for Schools project addresses these issues by developing Wind Application Centers (WACs) at universities; WAC students assist in implementing school wind turbines and participate in wind courses, by installing small wind turbines at community "host" schools, by implementing teacher training with interactive curricula at each host school. This poster provides an overview of the first two years of the Wind for Schools project, primarily supporting activities in Colorado, Kansas, Nebraska, South Dakota, Montana, and Idaho.

  16. Avian use of proposed KENETECH and CARES wind farm sites in Klickitat County, Washington. Appendix C to Washington Windplant No. 1 EIS. Technical report

    International Nuclear Information System (INIS)

    1995-01-01

    The Columbia Hills area above (north of) the Columbia River in Klickitat County, in southcentral Washington, is being considered for development of two wind power generation projects that could include the eventual placement of up to 436 wind turbines. The KENETECH Windpower Washington Windplant TM Number 1 project would include placing up to 345 KENETECH 33M-VS turbines, capable of producing up to 115 megawatts (MW), in 39 rows (strings) on a 5,110-hectare (12,630-acre) site. During scoping for these proposed developments, concerns were raised regarding the potential for avian mortality associated with wind farm development. Collision with wind turbine blade, towers, guy wires, and transmission lines, and electrocution from power lines have been identified as sources of avian mortality, particularly raptors, at existing wind farm facilities. To address these concerns, an avian study was conducted at the site in accordance with an avian study plan and protocol developed, with input from a national avian task force, state agencies (Washington Department of Fish and Wildlife [WDFW]), and federal agencies (USFWS). The study included four elements: (1) a winter raptor and waterfowl study, (2) spring migration and fall migration studies, (3) a summer resident study, and (4) a raptor breeding study. The study involved extensive field studies conducted by biologists experienced in identifying raptors and other birds

  17. Influence of pile–soil interaction on the dynamic properties of offshore wind turbines supported by jacket foundations

    DEFF Research Database (Denmark)

    Yi, Jin-Hak; Kim, Sun-Bin; Yoon, Gil-Lim

    2015-01-01

    are conventionally used in the oil and gas industry. However, there are still several issues unsolved for utilization of jacket structures for OWTs including pile–soil-interaction (PSI) effects, dynamically stable design, installation, and so on. In this study,the effects of pile–soil interaction on the dynamic...... properties of jacketsupported OWTs are investigated. The jacket structure is modeled as a four-legged multi-member structure with vertical pre-piles, and the PSI effects on dynamic properties of the structure are evaluated using Monte Carlo simulation considering uncertainties in soil properties.......Monopiles are the most widely utilized foundation for offshore wind turbines (OWTs) in shallow waters. However, jacket-type foundations are being considered as one of the good alternatives to monopole foundations for relatively deep water in the range of 25–50 m of water depth. Jacket structures...

  18. Interactive Macroeconomics

    Science.gov (United States)

    Di Guilmi, Corrado; Gallegati, Mauro; Landini, Simone

    2017-04-01

    Preface; List of tables; List of figures, 1. Introduction; Part I. Methodological Notes and Tools: 2. The state space notion; 3. The master equation; Part II. Applications to HIA Based Models: 4. Financial fragility and macroeconomic dynamics I: heterogeneity and interaction; 5. Financial fragility and macroeconomic Dynamics II: learning; Part III. Conclusions: 6. Conclusive remarks; Part IV. Appendices and Complements: Appendix A: Complements to Chapter 3; Appendix B: Solving the ME to solve the ABM; Appendix C: Specifying transition rates; Index.

  19. High speed video shooting with continuous-wave laser illumination in laboratory modeling of wind - wave interaction

    Science.gov (United States)

    Kandaurov, Alexander; Troitskaya, Yuliya; Caulliez, Guillemette; Sergeev, Daniil; Vdovin, Maxim

    2014-05-01

    Three examples of usage of high-speed video filming in investigation of wind-wave interaction in laboratory conditions is described. Experiments were carried out at the Wind - wave stratified flume of IAP RAS (length 10 m, cross section of air channel 0.4 x 0.4 m, wind velocity up to 24 m/s) and at the Large Air-Sea Interaction Facility (LASIF) - MIO/Luminy (length 40 m, cross section of air channel 3.2 x 1.6 m, wind velocity up to 10 m/s). A combination of PIV-measurements, optical measurements of water surface form and wave gages were used for detailed investigation of the characteristics of the wind flow over the water surface. The modified PIV-method is based on the use of continuous-wave (CW) laser illumination of the airflow seeded by particles and high-speed video. During the experiments on the Wind - wave stratified flume of IAP RAS Green (532 nm) CW laser with 1.5 Wt output power was used as a source for light sheet. High speed digital camera Videosprint (VS-Fast) was used for taking visualized air flow images with the frame rate 2000 Hz. Velocity air flow field was retrieved by PIV images processing with adaptive cross-correlation method on the curvilinear grid following surface wave profile. The mean wind velocity profiles were retrieved using conditional in phase averaging like in [1]. In the experiments on the LASIF more powerful Argon laser (4 Wt, CW) was used as well as high-speed camera with higher sensitivity and resolution: Optronics Camrecord CR3000x2, frame rate 3571 Hz, frame size 259×1696 px. In both series of experiments spherical 0.02 mm polyamide particles with inertial time 7 ms were used for seeding airflow. New particle seeding system based on utilization of air pressure is capable of injecting 2 g of particles per second for 1.3 - 2.4 s without flow disturbance. Used in LASIF this system provided high particle density on PIV-images. In combination with high-resolution camera it allowed us to obtain momentum fluxes directly from

  20. Vibration Based Wind Turbine Tower Foundation Design Utilizing Soil-Foundation-Structure Interaction

    Science.gov (United States)

    Al Satari, P. E. Mohamed; Hussain, S. E. Saif

    2008-07-01

    Wind turbines have been used to generate electricity as an alternative energy source to conventional fossil fuels. This case study is for multiple wind towers located at different villages in Alaska where severe arctic weather conditions exist. The towers are supported by two different types of foundations; large mat or deep piles foundations. Initially, a Reinforced Concrete (RC) mat foundation was utilized to provide the system with vertical and lateral support. Where soil conditions required it, a pile foundation solution was devised utilizing a 30″ thick RC mat containing an embedded steel grillage of W18 beams supported by 20″-24″ grouted or un-grouted piles. The mixing and casting of concrete in-situ has become the major source of cost and difficulty of construction at these remote Alaska sites. An all-steel foundation was proposed for faster installation and lower cost, but was found to impact the natural frequencies of the structural system by significantly softening the foundation system. The tower-foundation support structure thus became near-resonant with the operational frequencies of the wind turbine leading to a likelihood of structural instability or even collapse. A detailed 3D Finite-Element model of the original tower-foundation-pile system with RC foundation was created using SAP2000. Soil springs were included in the model based on soil properties obtained from the geotechnical consultant. The natural frequency from the model was verified against the tower manufacturer analytical and the experimental values. Where piles were used, numerous iterations were carried out to eliminate the need for the RC and optimize the design. An optimized design was achieved with enough separation between the natural and operational frequencies to prevent damage to the structural system eliminating the need for any RC encasement to the steel foundation or grouting to the piles.

  1. Impact of macrozoobenthic bioturbation and wind fluctuation interactions on net methylmercury in freshwater lakes.

    Science.gov (United States)

    Wang, Peifang; Yao, Yu; Wang, Chao; Hou, Jun; Qian, Jin; Miao, Lingzhan

    2017-11-01

    The methylmercury (MeHg) as the toxic fractions has presented significant threats to biota in freshwater ecosystems. Hg methylation process is demonstrated to be manipulated by biota process (benthic disturbance and algae bloom existence) as well as the abiotic influence (wind fluctuation and illumination intensity) in freshwater ecosystems. However, the mechanisms influencing Hg methylation are still unclear, and the coupled influences of the biotic and abiotic process with the shifts in variation on methylmercury remain unexplored. Accordingly, an annular flume experiment which simulated the freshwater ecosystem, was conducted for 108 days to examine the influences of typical disturbance by chironomid larvae and wind fluctuations on MeHg variation in sediment profiles. The in-situ, passive sampler technique of revealing diffusive gradients in thin films (DGT) encompassed the special resin, based on referenced extraction and coloration-computer imaging densitometry, were employed to obtain labile MeHg, Fe, and S concentrations at high resolution. The results indicate that larval bioturbation during the initial period of the experiment could diminish bioavailable MeHg concentrations and change the diffusion direction of MeHg fluxes. However, this inhibitive effect on MeHg concentrations ceased with larvae eclosion. Compared to bioturbation, wind fluctuation exerted slow but sustained inhibition on MeHg release. Furthermore, the eight parameters (dissolved organic carbon (DOC), DO, labile Fe and S concentrations, pH, sulfate-reducing bacteria (SRB) abundance in sediment, oxidation-reduction potential (ORP) and EC) could explain more of variation in MeHg concentrations which indicated by the canonical correspondence analysis. And these eight parameters manifest higher explanatory power for MeHg distributed in newly formed sediment. More notably, the comparison results of the multiple and simple regression directly demonstrated the DOC was the fundamental and robust

  2. Computationally Efficient Modelling of Dynamic Soil-Structure Interaction of Offshore Wind Turbines on Gravity Footings

    DEFF Research Database (Denmark)

    Damgaard, Mads; Andersen, Lars Vabbersgaard; Ibsen, Lars Bo

    2014-01-01

    The formulation and quality of a computationally efficient model of offshore wind turbine surface foundations is examined. The aim is to establish a model, workable in the frequency and time domain, that can be applied in aeroelastic codes for fast and reliable evaluation of the dynamic structural...... to wave propagating in the subsoil–even for soil stratifications with low cut-in frequencies. In this regard, utilising discrete second-order models for the physical interpretation of a rational filter puts special demands on the Newmark β-scheme, where the time integration in most cases only provides...

  3. Grid interaction of offshore wind farms. Part 1. Models for dynamic simulation

    Science.gov (United States)

    Morren, Johan; Pierik, Jan T. G.; de Haan, Sjoerd W. H.; Bozelie, Jan

    2005-07-01

    In this contribution, dynamic wind farm models suitable for fast simulation of power systems are presented. While deriving the models, special attention has been paid to increasing the computational speed of the simulation program. An important increase in speed is realized by the use of the well-known dq0 transformation (Park transformation) not only for the generator but also for all other electrical components. The use of the Park transformation is common practice in electrical machine models, but not in the modelling of other electrical components. For single turbines, simulations in the dq0 reference frame are 100 times faster than simulations in the abc reference frame. After a discussion of the Park transformation and its most important properties, it is explained how models in the dq0 reference frame can be obtained. The dq0 models of the most important electrical components are presented. The mechanical and aerodynamic models that are needed for dynamic simulation of wind turbines are discussed briefly. The models are applied in Part 2. Copyright

  4. Model of the saltation transport by Discrete Element Method coupled with wind interaction

    Directory of Open Access Journals (Sweden)

    Oger Luc

    2017-01-01

    Full Text Available We study the Aeolian saltation transport problem by analysing the collision of incident energetic beads with granular packing. We investigate the collision process for the case where the incident bead and those from the packing have identical mechanical properties. We analyse the features of the consecutive collision process. We used a molecular dynamics method known as DEM (soft Discrete Element Method with 20000 particles (2D. The grains were displayed randomly in a box (250X60. A few incident disks are launched with a constant velocity and angle with high random position to initiate the flow. A wind velocity profile is applied on the flowing zone of the saltation. The velocity profile is obtained by the calculi of the counter-flow due to the local packing fraction induced by the granular flow. We analyse the evolution of the upper surface of the disk packing. In the beginning, the saltation process can be seen as the classical “splash function” in which one bead hits a fully static dense packing. Then, the quasi-fluidized upper layer of the packing creates a completely different behaviour of the “animated splash function”. The dilation of the upper surface due to the previous collisions is responsible for a need of less input energy for launching new ejected disks. This phenomenon permits to maintain a constant granular flow with a “small” wind velocity on the surface of the disk bed.

  5. Plume and Shock Interaction Effects on Sonic Boom in the 1-foot by 1-foot Supersonic Wind Tunnel

    Science.gov (United States)

    Castner, Raymond; Elmiligui, Alaa; Cliff, Susan; Winski, Courtney

    2015-01-01

    The desire to reduce or eliminate the operational restrictions of supersonic aircraft over populated areas has led to extensive research at NASA. Restrictions are due to the disturbance of the sonic boom, caused by the coalescence of shock waves formed by the aircraft. A study has been performed focused on reducing the magnitude of the sonic boom N-wave generated by airplane components with a focus on shock waves caused by the exhaust nozzle plume. Testing was completed in the 1-foot by 1-foot supersonic wind tunnel to study the effects of an exhaust nozzle plume and shock wave interaction. The plume and shock interaction study was developed to collect data for computational fluid dynamics (CFD) validation of a nozzle plume passing through the shock generated from the wing or tail of a supersonic vehicle. The wing or tail was simulated with a wedgeshaped shock generator. This test entry was the first of two phases to collect schlieren images and off-body static pressure profiles. Three wedge configurations were tested consisting of strut-mounted wedges of 2.5- degrees and 5-degrees. Three propulsion configurations were tested simulating the propulsion pod and aft deck from a low boom vehicle concept, which also provided a trailing edge shock and plume interaction. Findings include how the interaction of the jet plume caused a thickening of the shock generated by the wedge (or aft deck) and demonstrate how the shock location moved with increasing nozzle pressure ratio.

  6. Potential health impact of wind turbines

    International Nuclear Information System (INIS)

    2010-05-01

    In response to public health concerns about wind turbines, a study was conducted to review the scientific evidence on the potential health effects of wind turbines. Several research questions were examined, including scientific evidence on the potential health impacts of wind turbines; the relationship between wind turbine noise and health; the relationship between low frequency sound, infrasound and health; assessment of exposure to wind turbines; wind turbine health and safety hazards and Ontario wind turbine setbacks; community consultation prior to wind farm construction and data gaps and research needs. The study showed that although some people living near wind turbines reported symptoms such as dizziness, headaches, and sleep disturbance, the scientific evidence available to date does not demonstrate a direct causal link between wind turbine noise and adverse health effects. The sound level from wind turbines at common residential setbacks is not sufficient to cause hearing impairment or other direct health effects, although some people may find it annoying. 41 refs., 1 appendix.

  7. Potential health impact of wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2010-05-15

    In response to public health concerns about wind turbines, a study was conducted to review the scientific evidence on the potential health effects of wind turbines. Several research questions were examined, including scientific evidence on the potential health impacts of wind turbines; the relationship between wind turbine noise and health; the relationship between low frequency sound, infrasound and health; assessment of exposure to wind turbines; wind turbine health and safety hazards and Ontario wind turbine setbacks; community consultation prior to wind farm construction and data gaps and research needs. The study showed that although some people living near wind turbines reported symptoms such as dizziness, headaches, and sleep disturbance, the scientific evidence available to date does not demonstrate a direct causal link between wind turbine noise and adverse health effects. The sound level from wind turbines at common residential setbacks is not sufficient to cause hearing impairment or other direct health effects, although some people may find it annoying. 41 refs., 1 appendix.

  8. A Three-Dimensional Model of Pluto's Interaction With the Solar Wind During the New Horizons Encounter

    Science.gov (United States)

    Feyerabend, Moritz; Liuzzo, Lucas; Simon, Sven; Motschmann, Uwe

    2017-10-01

    We apply a hybrid (kinetic ions and fluid electrons) simulation model to study Pluto's plasma environment during the New Horizons encounter on 14 July 2015. We show that Pluto's plasma interaction is dominated by significant north-south asymmetries, driven by large pickup ion gyroradii on the order of 200 Pluto radii. The transition region from the ambient solar wind to the population of plutogenic ions (called the "Plutopause") also shows considerable asymmetries that cannot be explained by a fluid picture. Since the New Horizons spacecraft does not carry a magnetometer, we use our model to estimate the strength and direction of the interplanetary magnetic field (IMF) at the time of the flyby by comparing output from the hybrid simulation to the plasma signatures observed during the New Horizons encounter. We find that an IMF strength of at least 0.24 nT is required to generate the observed plasma signatures. An IMF orientation either parallel or antiparallel to Pluto's orbital motion is able to explain the observed plasma densities and velocities along the New Horizons trajectory. Our simulations are able to quantitatively reproduce all key features of the plasma observations, specifically the gradual slowing of the solar wind, as well as the location and thickness of the Plutopause and bow shock.

  9. Fault Tolerant Wind Farm Control

    DEFF Research Database (Denmark)

    Odgaard, Peter Fogh; Stoustrup, Jakob

    2013-01-01

    In the recent years the wind turbine industry has focused on optimizing the cost of energy. One of the important factors in this is to increase reliability of the wind turbines. Advanced fault detection, isolation and accommodation are important tools in this process. Clearly most faults are dealt...... with best at a wind turbine control level. However, some faults are better dealt with at the wind farm control level, if the wind turbine is located in a wind farm. In this paper a benchmark model for fault detection and isolation, and fault tolerant control of wind turbines implemented at the wind farm...... control level is presented. The benchmark model includes a small wind farm of nine wind turbines, based on simple models of the wind turbines as well as the wind and interactions between wind turbines in the wind farm. The model includes wind and power references scenarios as well as three relevant fault...

  10. Noise and noise disturbances from wind power plants - Tests with interactive control of sound parameters for more comfortable and less perceptible sounds

    International Nuclear Information System (INIS)

    Persson-Waye, K.; Oehrstroem, E.; Bjoerkman, M.; Agge, A.

    2001-12-01

    In experimental pilot studies, a methodology has been worked out for interactively varying sound parameters in wind power plants. In the tests, 24 persons varied the center frequency of different band-widths, the frequency of a sinus-tone and the amplitude-modulation of a sinus-tone in order to create as comfortable a sound as possible. The variations build on the noise from the two wind turbines Bonus and Wind World. The variations were performed with a constant dba level. The results showed that the majority preferred a low-frequency tone (94 Hz and 115 Hz for Wind World and Bonus, respectively). The mean of the most comfortable amplitude-modulation varied between 18 and 22 Hz, depending on the ground frequency. The mean of the center-frequency for the different band-widths varied from 785 to 1104 Hz. In order to study the influence of the wind velocity on the acoustic character of the noise, a long-time measurement program has been performed. A remotely controlled system has been developed, where wind velocity, wind direction, temperature and humidity are registered simultaneously with the noise. Long-time registrations have been performed for four different wing turbines

  11. Multi-fluid MHD study of the solar wind interaction with Venus at Solar max and Solar min conditions.

    Science.gov (United States)

    Ma, Y. J.; Nagy, A. F.; Russell, C. T.; Najib, D.; Toth, G.

    2012-09-01

    We study the solar wind interaction with Venus, using a new advanced multi-fluid MHD model that has been developed recently. The model is similar to the numerical model that was successfully applied to Mars (Najib et al., 2011). Mass densities, velocities and pressures of the protons and three important ionosphere ion species (O+, O2+ and CO2+) are self-consistently calculated by solving the individual coupled continuity, momentum and energy equations. The various chemical reactions and ion-neutral collision processes are considered in the model. The simulation domain covers the region from 100 km altitude above the surface up to 16 RV in the tail. An adaptive spherical grid structure is constructed with radial resolution of about 10 km in the lower ionosphere. The model is applied to both solar-maximum and solar-minimum conditions and model results are compared in detail with multi-species single fluid model results and VEX observations.

  12. Natural frequency of bottom-fixed offshore wind turbines considering pile-soil-interaction with material uncertainties and scouring depth

    DEFF Research Database (Denmark)

    Yi, Jin-Hak; Kim, Sun-Bin; Yoon, Gil-Lim

    2015-01-01

    include pile-soil-interaction (PSI) effects, realization of dynamically stable designs to avoid resonances, and quick and safe installation in remote areas. In this study, the effects of PSI on the dynamic properties of bottom-fixed OWTs, including monopile-, tripod-and jacket-supported OWTs, were......Monopileshave been most widely used for supporting offshore wind turbines (OWTs) in shallow waterareas. However, multi-member lattice-type structures such as jackets and tripods are also considered good alternatives to monopile foundations for relatively deep waterareaswith depth ranging from 25......–50 m owing to their technical and economic feasibility. Moreover, jacket structures have been popular in the oil and gas industry for a long time. However, several unsolved technical issues still persist in the utilization of multi-member lattice-type supporting structures for OWTs; these problems...

  13. Non-linear vehicle-bridge-wind interaction model for running safety assessment of high-speed trains over a high-pier viaduct

    Science.gov (United States)

    Olmos, José M.; Astiz, Miguel Á.

    2018-04-01

    In order to properly study the high-speed traffic safety on a high-pier viaduct subject to episodes of lateral turbulent winds, an efficient dynamic interaction train-bridge-wind model has been developed and experimentally validated. This model considers the full wheel and rail profiles, the friction between these two bodies in contact, and the piers P-Delta effect. The model has been used to determine the critical train and wind velocities from which the trains cannot travel safely over the O'Eixo Bridge. The dynamic simulations carried out and the results obtained in the time domain show that traffic safety rates exceed the allowed limits for turbulent winds with mean velocities at the deck higher than 25 m/s.

  14. Wall interaction effects for a full-scale helicopter rotor in the NASA Ames 80- by 120-foot wind tunnel

    Science.gov (United States)

    Shinoda, Patrick M.

    1994-01-01

    A full-scale helicopter rotor test was conducted in the NASA Ames 80- by 120-Foot Wind Tunnel with a four-bladed S-76 rotor system. This wind tunnel test generated a unique and extensive data base covering a wide range of rotor shaft angles-of-attack and rotor thrust conditions from 0 to 100 knots. Three configurations were tested: (1) empty tunnel; (2) test stand body (fuselage) and support system; and (3) fuselage and support system with rotor installed. Empty tunnel wall pressure data are evaluated as a function of tunnel speed to understand the baseline characteristics. Aerodynamic interaction effects between the fuselage and the walls of the tunnel are investigated by comparing wall, ceiling, and floor pressures for various tunnel velocities and fuselage angles-of-attack. Aerodynamic interaction effects between the rotor and the walls of the tunnel are also investigated by comparing wall, ceiling, and floor pressures for various rotor shaft angles, rotor thrust conditions, and tunnel velocities. Empty tunnel wall pressure data show good repeatability and are not affected by tunnel speed. In addition, the tunnel wall pressure profiles are not affected by the presence of the fuselage apart from a pressure shift. Results do not indicate that the tunnel wall pressure profiles are affected by the presence of the rotor. Significant changes in the wall, ceiling, and floor pressure profiles occur with changing tunnel speeds for constant rotor thrust and shaft angle conditions. Significant changes were also observed when varying rotor thrust or rotor shaft angle-of-attack. Other results indicate that dynamic rotor loads and blade motion are influenced by the presence of the tunnel walls at very low tunnel velocity and, together with the wall pressure data, provide a good indication of flow breakdown.

  15. Wind tunnel investigation of the interaction and breakdown characteristics of slender wing vortices at subsonic, transonic, and supersonic speeds

    Science.gov (United States)

    Erickson, Gary E.

    1991-01-01

    The vortex dominated aerodynamic characteristics of a generic 65 degree cropped delta wing model were studied in a wind tunnel at subsonic through supersonic speeds. The lee-side flow fields over the wing-alone configuration and the wing with leading edge extension (LEX) added were observed at M (infinity) equals 0.40 to 1.60 using a laser vapor screen technique. These results were correlated with surface streamline patterns, upper surface static pressure distributions, and six-component forces and moments. The wing-alone exhibited vortex breakdown and asymmetry of the breakdown location at the subsonic and transonic speeds. An earlier onset of vortex breakdown over the wing occurred at transonic speeds due to the interaction of the leading edge vortex with the normal shock wave. The development of a shock wave between the vortex and wing surface caused an early separation of the secondary boundary layer. With the LEX installed, wing vortex breakdown asymmetry did not occur up to the maximum angle of attack in the present test of 24 degrees. The favorable interaction of the LEX vortex with the wing flow field reduced the effects of shock waves on the wing primary and secondary vortical flows. The direct interaction of the wing and LEX vortex cores diminished with increasing Mach number. The maximum attainable vortex-induced pressure signatures were constrained by the vacuum pressure limit at the transonic and supersonic speeds.

  16. Wave-Particle Interactions in the Radiation Belts, Aurora,and Solar Wind: Opportunities for Lab Experiments

    Science.gov (United States)

    Kletzing, C.

    2017-12-01

    The physics of the creation, loss, and transport of radiation belt particles is intimately connected to the electric and magnetic fields which mediate these processes. A large range of field and particle interactions are involved in this physics from large-scale ring current ion and magnetic field dynamics to microscopic kinetic interactions of whistler-mode chorus waves with energetic electrons. To measure these kinds of radiation belt interactions, NASA implemented the two-satellite Van Allen Probes mission. As part of the mission, the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) investigation is an integrated set of instruments consisting of a triaxial fluxgate magnetometer (MAG) and a Waves instrument which includes a triaxial search coil magnetometer (MSC). We show a variety of waves thought to be important for wave particle interactionsin the radiation belts: low frequency ULF pulsations, EMIC waves, and whistler mode waves including upper and lower band chorus. Outside ofthe radiation belts, Alfven waves play a key role in both solar wind turbulenceand auroral particle acceleration. Several of these wave modes could benefit (or have benefitted) from laboratory studies to further refineour understanding of the detailed physics of the wave-particle interactionswhich lead to energization, pitch angle scattering, and cross-field transportWe illustrate some of the processes and compare the wave data with particle measurements to show relationships between wave activity and particle processobserved in the inner magnetosphere and heliosphere.

  17. Pilot plant environmental conditions (OPDD Appendix C)

    Energy Technology Data Exchange (ETDEWEB)

    Randall, C.M.; Whitson, M.E.; Coggi, J.V.

    1978-08-15

    This is Appendix C to the Pilot Plant Overall Plant design description document for the 10-MW pilot central receiver plant to be located at Barstow, California. The environmental design criteria to be used for plant design day performance, operational limits, and survival environmental limits are specified. Data are presented on insolation, wind, temperature, and other meteorological conditions. (WHK)

  18. Wind Turbine Rotor-Tower Interaction Using an Incompressible Overset Grid Method

    DEFF Research Database (Denmark)

    Zahle, Frederik; Sørensen, Niels N.; Johansen, Jeppe

    2009-01-01

    are in good agreement with the experimental data available. The interaction between the rotor and the tower induces significant increases in the transient loads on the blades and is characterized by an instant deloading and subsequent reloading of the blade, associated with the velocity deficit in the wake......, combined with the interaction with the shed vortices, which causes a strongly time-varying response. Finally, the results show that the rotor has a strong effect on the tower shedding frequency, causing under certain flow conditions vortex lock-in to take place on the upper part of the tower. Copyright...

  19. WINDS: A Web-Based Intelligent Interactive Course on Data-Structures

    Science.gov (United States)

    Sirohi, Vijayalaxmi

    2007-01-01

    The Internet has opened new ways of learning and has brought several advantages to computer-aided education. Global access, self-paced learning, asynchronous teaching, interactivity, and multimedia usage are some of these. Along with the advantages comes the challenge of designing the software using the available facilities. Integrating online…

  20. Interaction of Urban Heating and Local Winds During the Calm Intermonsoon Seasons in the Tropics

    Science.gov (United States)

    Ooi, M. C. G.; Chan, A.; Subramaniam, K.; Morris, K. I.; Oozeer, M. Y.

    2017-11-01

    Rapid urbanization of cities has greatly modified the thermal and dynamic profile in the urban boundary layer. This paper attempts to study the interaction of urban heating and the local topographic-induced flow circulation for a tropical coastal city, Greater Kuala Lumpur, in Malaysia. The role of sea-and-valley-breeze-orientated synoptic flow (SBOS) on the interaction is determined by comparing two intermonsoon periods. A state-of-the-art numerical model, Advanced Research Weather Research and Forecasting model, is used to identify the influence of urbanization through modification of urban surfaces. The model reasonably reproduces the vertical sounding data and near-surface weather parameters. The diurnal urban heating pattern is attributed to three predominant factors: (i) weak under calm and clear-sky condition (morning heating), (ii) weak under larger atmospheric moisture content (late afternoon convection), and (iii) largest (1.4°C) due to differential cooling rate of urban and rural surface at night. The interaction of urban thermals and upper level SBOS affects the effect of urbanization on local circulation during the day. The urban thermals reduce the weak opposing SBOS (2 m s-1) suppresses the vertical lifting of urban thermals and decelerates the sea breeze front. It is discovered that the interaction of urban heating and topographic-induced flow is interdependent while the synoptic flow plays a critical role in modifying both factors, respectively.

  1. Solar-wind ion interaction with carbonates on the surface of Ceres: Laboratory Experiments

    Science.gov (United States)

    Dukes, C. A.; Bu, C.; Lopez, G. R.; McFadden, L. A.; Ruesch, O.; Li, J. Y.

    2017-12-01

    Bright carbonates deposits on the dark background of Ceres have been identified by Dawn's VIR spectrometer [1, 2], with a composition that varies from Na2CO3 at Oxo crater and the Cerealia and Vinalia Faculae where carbonates are most abundant, to MgCO3 or CaCO3 in other regions [2, 3]. Solar-wind plasma impacts the surface of airless planetary bodies with 1 keV/amu H and He ( 107 ions cm-2 s-1at 2.8 A.U.), causing chemical and physical changes that influence the optical spectra. We investigate the stability of carbonate salts under ion irradiation, monitoring the spectral and compositional change. Anhydrous Na2CO3 (natrite) powders (grains 80% original material reflectance. Both hydrous and anhydrous Na2CO3 show blue/green radio-luminescence under ion impact. Ion-induced darkening of Ceres' natrite deposits is expected to occur on a time-scale of 100 - 1000 years, significantly less than the age of Cerealia facula 7 Ma [4]; darkening can be reversed by exposure to water vapor. For Ceres bright regions of varied albedo, this suggests that the brightest areas are the more recent deposits or the most recently exposed to water by upwelling, venting, or sublimation of subsurface ice [5]. [1] DeSanctis et al (2016) Nature 536, 54 - 57 [2] Palumbo et al (2016) LPSC 47, 2166 [3] Tosi et al (2016) DPS48, 511.06 [4] Nathues et al (2017) APJ 153, 112-124 [5] Titus (2015) GRL 42, 2130-2136

  2. Mercury's Solar Wind Interaction as Characterized by Magnetospheric Plasma Mantle Observations With MESSENGER

    Science.gov (United States)

    Jasinski, Jamie M.; Slavin, James A.; Raines, Jim M.; DiBraccio, Gina A.

    2017-12-01

    We analyze 94 traversals of Mercury's southern magnetospheric plasma mantle using data from the MESSENGER spacecraft. The mean and median proton number densities in the mantle are 1.5 and 1.3 cm-3, respectively. For sodium number density these values are 0.004 and 0.002 cm-3. Moderately higher densities are observed on the magnetospheric dusk side. The mantle supplies up to 1.5 × 108 cm-2 s-1 and 0.8 × 108 cm-2 s-1 of proton and sodium flux to the plasma sheet, respectively. We estimate the cross-electric magnetospheric potential from each observation and find a mean of 19 kV (standard deviation of 16 kV) and a median of 13 kV. This is an important result as it is lower than previous estimations and shows that Mercury's magnetosphere is at times not as highly driven by the solar wind as previously thought. Our values are comparable to the estimations for the ice giant planets, Uranus and Neptune, but lower than Earth. The estimated potentials do have a very large range of values (1-74 kV), showing that Mercury's magnetosphere is highly dynamic. A correlation of the potential is found to the interplanetary magnetic field (IMF) magnitude, supporting evidence that dayside magnetic reconnection can occur at all shear angles at Mercury. But we also see that Mercury has an Earth-like magnetospheric response, favoring -BZ IMF orientation. We find evidence that -BX orientations in the IMF favor the southern cusp and southern mantle. This is in agreement with telescopic observations of exospheric emission, but in disagreement with modeling.

  3. A HPC “Cyber Wind Facility” Incorporating Fully-Coupled CFD/CSD for Turbine-Platform-Wake Interactions with the Atmosphere and Ocean

    Energy Technology Data Exchange (ETDEWEB)

    Brasseur, James G. [Univ. of Colorado, Boulder, CO (United States)

    2017-05-09

    The central aims of the DOE-supported “Cyber Wind Facility” project center on the recognition that wind turbines over land and ocean generate power from atmospheric winds that are inherently turbulent and strongly varying, both spatially over the rotor disk and in temporally as the rotating blades pass through atmospheric eddies embedded within the mean wind. The daytime unstable atmospheric boundary layer (ABL) is particularly variable in space time as solar heating generates buoyancy-driven motions that interact with strong mean shear in the ABL “surface layer,” the lowest 200 - 300 m where wind turbines reside in farms. With the “Cyber Wind Facility” (CWF) program we initiate a research and technology direction in which “cyber data” are generated from “computational experiments” within a “facility” akin to a wind tunnel, but with true space-time atmospheric turbulence that drive utility-scale wind turbines at full-scale Reynolds numbers. With DOE support we generated the key “modules” within a computational framework to create a first generation Cyber Wind Facility (CWF) for single wind turbines in the daytime ABL---both over land where the ABL globally unstable and over water with closer-to-neutral atmospheric conditions but with time response strongly affected by wave-induced forcing of the wind turbine platform (here a buoy configuration). The CWF program has significantly improved the accuracy of actuator line models, evaluated with the Cyber Wind Facility in full blade-boundary-layer-resolved mode. The application of the CWF made in this program showed the existence of important ramp-like response events that likely contribute to bearing fatigue failure on the main shaft and that the advanced ALM method developed here captures the primary nonsteady response characteristics. Long-time analysis uncovered distinctive key dynamics that explain primary mechanisms that underlie potentially deleterious load transients. We also showed

  4. Propulsion and airframe aerodynamic interactions of supersonic V/STOL configurations. Volume 2: Wind tunnel test force and moment data report

    Science.gov (United States)

    Zilz, D. E.

    1985-01-01

    A wind tunnel model of a supersonic V/STOL fighter configuration has been tested to measure the aerodynamic interaction effects which can result from geometrically close-coupled propulsion system/airframe components. The approach was to configure the model to represent two different test techniques. One was a conventional test technique composed of two test modes. In the Flow-Through mode, absolute configuration aerodynamics are measured, including inlet/airframe interactions. In the Jet-Effects mode, incremental nozzle/airframe interactions are measured. The other test technique is a propulsion simulator approach, where a sub-scale, externally powered engine is mounted in the model. This allows proper measurement of inlet/airframe and nozzle/airframe interactions simultaneously. This is Volume 2 of 2: Wind Tunnel Test Force and Moment Data Report.

  5. Appendix A

    DEFF Research Database (Denmark)

    Henriksen, M. S.; Brincker, Rune; Heshe, Gert

    1999-01-01

    In this appendix a brief summary of experiments on reinforced concrete beams in three-point bending performed at Aalborg University is given. The aim of the investigation is to determine the full load-deflection curves for different beam sizes, different types of concrete and different amounts...

  6. Appendix B

    DEFF Research Database (Denmark)

    Christensen, F. A.; Brincker, Rune

    1999-01-01

    In this appendix the failure behaviour of lightly reinforced concrete beams is investigated. A numerical model based on the fictitious crack approach according to Hillerborg [1] is established in order to estimate the load-deflection curve for lightly reinforced concrete beams. The debonding...

  7. Appendix C

    DEFF Research Database (Denmark)

    Christensen, F. A.; Henriksen, M. S.; Brincker, Rune

    1999-01-01

    In this appendix a model is formulated for the rotational capacity of reinforced concrete beams assuming rebar tension failure. The model is based on a classical approach and establishes the load-deflection curve of a reinforced concrete beam. The rotational capacity is then obtained as the area...

  8. Wing-Body Interaction: Numerical simulation, Wind-tunnel and In-flight Testing

    Czech Academy of Sciences Publication Activity Database

    Popelka, Lukáš; Zelený, L.; Šimurda, David; Matějka, M.

    2010-01-01

    Roč. 34, č. 2 (2010), s. 29-36 ISSN 0744-8996. [OSTIV CONGRESS /29./. Lüsse, 06.08.2008-13.08.2008] R&D Projects: GA MŠk(CZ) 1M06031; GA AV ČR IAA2076403; GA ČR GA101/08/1155 Institutional research plan: CEZ:AV0Z20760514 Keywords : wing-fuselage interaction * turbulent separation * vortex generators Subject RIV: BK - Fluid Dynamics

  9. Solar-wind turbulence and shear: a superposed-epoch analysis of corotating interaction regions at 1 AU

    Energy Technology Data Exchange (ETDEWEB)

    Borovsky, Joseph E [Los Alamos National Laboratory; Denton, Michael H [LANCASTER UNIV.

    2009-01-01

    A superposed-epoch analysis of ACE and OMNI2 measurements is performed on 27 corotating interaction regions (CIRs) in 2003-2008, with the zero epoch taken to be the stream interface as determined by the maximum of the plasma vorticity. The structure of CIRs is investigated. When the flow measurements are rotated into the local-Parker-spiral coordinate system the shear is seen to be abrupt and intense, with vorticities on the order of 10{sup -5}-10{sup -4} sec{sup -1}. Converging flows perpendicular to the stream interface are seen in the local-Parker-spiral coordinate system and about half of the CIRs show a layer of divergent rebound flow away from the stream interface. Arguments indicate that any spreading of turbulence away from the region where it is produced is limited to about 10{sup 6} km, which is very small compared with the thickness of a CrR. Analysis of the turbulence across the CrRs is performed. When possible, the effects of discontinuities are removed from the data. Fluctuation amplitudes, the Alfvenicity, and the level of Alfvenic correlations all vary smoothly across the CrR. The Alfven ratio exhibits a decrease at the shear zone of the stream interface. Fourier analysis of 4.5-hr subintervals of ACE data is performed and the results are superposed averaged as an ensemble of realizations. The spectral slopes of the velocity, magnetic-field, and total-energy fluctuations vary smoothly across the CIR. The total-energy spectral slope is {approx} 3/2 in the slow and fast wind and in the CrRs. Analysis of the Elsasser inward-outward fluctuations shows a smooth transition across the CrR from an inward-outward balance in the slow wind to an outward dominance in the fast wind. A number of signatures of turbulence driving at the shear zone are sought (entropy change, turbulence amplitude, Alfvenicity, Alfven ratio, spectral slopes, in-out nature): none show evidence of driving of turbulence by shear.

  10. Polarization light curve modelling of corotating interaction regions in the wind of the Wolf-Rayet star WR 6

    Science.gov (United States)

    St-Louis, N.; Tremblay, Patrick; Ignace, Richard

    2018-02-01

    The intriguing WN4b star WR 6 has been known to display epoch-dependent spectroscopic, photometric and polarimetric variability for several decades. In this paper, we set out to verify if a simplified analytical model in which corotating interaction regions (CIRs) threading an otherwise spherical wind is able to reproduce the many broad-band continuum light curves from the literature with a reasonable set of parameters. We modified the optically thin model developed by Ignace, St-Louis & Proulx-Giraldeau to approximately account for multiple scattering and used it to fit 13 separate data sets of this star. By including two CIRs in the wind, we obtained reasonable fits for all data sets with coherent values for the inclination of the rotation axis (i0 = 166°) and for its orientation in the plane of the sky, although in the latter case we obtained two equally acceptable values (ψ = 63° and 152°) from the polarimetry. Additional line profile variation simulations using the Sobolev approximation for the line transfer allowed us to eliminate the ψ = 152° solution. With the adopted configuration (i0 = 166° and ψ = 63°), we were able to reproduce all data sets relatively well with two CIRs located near the stellar equator and always separated by ˜90° in longitude. The epoch dependence comes from the fact that these CIRs migrate along the surface of the star. Density contrasts smaller than a factor of 2 and large opening angles for the CIR (β ⪆ 35°) were found to best reproduce the type of spectroscopic variability reported in the literature.

  11. Control System interaction in the VSC-HVDC Grid Connected Offshore Wind Power Plant

    DEFF Research Database (Denmark)

    Glasdam, Jakob Bærholm; Kocewiak, Łukasz Hubert; Hjerrild, Jesper

    2015-01-01

    or converter interaction studies have therefore become an important part of the system design studies of a high voltage alternating current (HVAC) grid connected OWPP. The voltage sourced converter high voltage direct current (VSC-HVDC) has become a preferred choice for grid connection of remotely located...... OWPPs. As for the HVAC grid connected OWPPs, there is a need to conduct harmonic stability studies in the design phase of an HVDC grid connected OWPP. As the offshore electrical environment is significantly altered compared to the offshore network in an HVAC connected OWPP, there is a need to define...... the procedure of the stability study and its application for the HVDC grid connected OWPPs. The purpose of this paper is to investigate the harmonic instability phenomena in HVDC grid connected OWPPs using both frequency and time domain simulations. A good correlation at lower frequencies between the two...

  12. The dynamics of buoyant jets in a linearly stratified ambient cross-flow: Implications for the interaction between volcanic plumes and wind

    Science.gov (United States)

    Carazzo, Guillaume; Girault, Frédéric; Aubry, Thomas; Bouquerel, Hélène; Kaminski, Édouard

    2014-05-01

    Volcanic plumes produced by explosive eruptions commonly interact with atmospheric wind causing plume bending and a reduction of its maximum rise height. It is well known that the maximum height reached by a buoyant plume rising in a cross-flow with uniform velocity is controlled by the plume buoyancy flux at the source, the strength of the initial environmental density stratification, the wind velocity and the efficiency of turbulent entrainment. Although numerous studies have been carried out to understand the effects of variations of environmental and source conditions on the plume maximum height, turbulent entrainment has not been taken into account with the same level of detailed analysis. Here, we present new laboratory experiments aimed at better understanding the contribution of the turbulent entrainment to determining the plume maximum height. The experiments consist in injecting downward fresh water in a tank containing an aqueous NaCl solution with linear density stratification. The jet source is towed at a constant speed through the stationary fluid in order to produce a cross-flow. According to the range of source and environmental conditions, the buoyant jet is distorted or bent-over and its maximum rise height is reduced up to a factor of 2 when wind speed is high. We quantify the efficiency of turbulent entrainment due to wind in our experiments and we show that the dynamical regime strongly depends on the ratio of the horizontal wind speed and the vertical plume velocity, and on the Richardson number defined at the source. Our results provide a robust framework to characterize the entrainment coefficient due to wind in a 1D model of turbulent jet rising in a linearly stratified ambient cross-flow, and hence can be used for the assessment of the impact of atmospheric winds on the dynamics of explosive volcanic plumes.

  13. Columbia Wind Farm number-sign 1 EIS: Botanical resources technical report for the Conservation and Renewable Energy System. Appendix B

    International Nuclear Information System (INIS)

    1995-01-01

    Jones and Stokes Associates conducted botanical investigations of the Conservation and Renewable Energy Systems (CARES) project site from April through July 1994. Presurvey investigations were conducted to gain information regarding potential special-status plant species and vegetation communities that might exist on the project area. Field surveys were conducted to determine the presence of special-status plant species, map and describe potential vegetation communities, and document the presence of other species onsite, including culturally important species. Field surveys also were used to identify possible mitigation measures as a means to reduce potential project impacts to botanical resources. Floristically, the project area is located in the Columbia Basin Province dominated by shrub-steppe grassland vegetation. Completion of the presurvey and field investigations documented that the project area is dominated by native bunchgrass communities. Field surveys also determined that no special-status plant species were found on the study area. Implementation of the project would result in moderately significant impacts to the vegetation resource. Impacts include the following direct impacts: removal or disturbance of approximately 38 hectares (95 acres) of vegetation, including 32 hectares (80 acres) of native, natural communities, from project construction and the initiation of development into relatively undisturbed native vegetation communities. Indirect impacts to vegetation are associated with impacts that could occur in the future. Ongoing activities that are required to maintain the site's function of producing wind power could result in vegetation trampling and removal of vegetation. This disturbance could create areas where invasive weeds could establish and provide a continual source of weed seed in the project area

  14. Validation of a simple aerodynamic model capable to predict the interaction effects occuring between two generic wind propulsion systems

    NARCIS (Netherlands)

    Bordogna, G.; Keuning, J.A.; Huijsmans, R.H.M.; Fossati, Fabio Vittorio; Belloli, Marco; Huijsmans, R.H.M.

    2016-01-01

    In recent years wind-assisted propulsion for commercial ships has gained an increasing interest as valuable alternative to reduce fuel pollutant emissions. However, the development of feasible and commercially viable wind propulsion systems to partially (or fully) propel a ship is nowadays hindered

  15. The intOA Experiment: A Study of Ocean-Atmosphere Interactions Under Moderate to Strong Offshore Winds and Opposing Swell Conditions in the Gulf of Tehuantepec, Mexico

    Science.gov (United States)

    Ocampo-Torres, F. J.; García-Nava, H.; Durazo, R.; Osuna, P.; Díaz Méndez, G. M.; Graber, H. C.

    2011-03-01

    The Gulf of Tehuantepec air-sea interaction experiment ( intOA) took place from February to April 2005, under the Programme for the Study of the Gulf of Tehuantepec (PEGoT, Spanish acronym for Programa para el Estudio del Golfo de Tehuantepec). PEGoT is underway aiming for better knowledge of the effect of strong and persistent offshore winds on coastal waters and their natural resources, as well as performing advanced numerical modelling of the wave and surface current fields. One of the goals of the intOA experiment is to improve our knowledge on air-sea interaction processes with particular emphasis on the effect of surface waves on the momentum flux for the characteristic and unique conditions that occur when strong Tehuano winds blow offshore against the Pacific Ocean long period swell. For the field campaign, an air-sea interaction spar (ASIS) buoy was deployed in the Gulf of Tehuantepec to measure surface waves and the momentum flux between the ocean and the atmosphere. High frequency radar systems (phase array type) were in operation from two coastal sites and three acoustic Doppler current profilers were deployed near-shore. Synthetic aperture radar images were also acquired as part of the remote sensing component of the experiment. The present paper provides the main results on the wave and wind fields, addressing the direct calculation of the momentum flux and the drag coefficient, and gives an overview of the intOA experiment. Although the effect of swell has been described in recent studies, this is the first time for the very specific conditions encountered, such as swell persistently opposing offshore winds and locally generated waves, to show a clear evidence of the influence on the wind stress of the significant steepness of swell waves.

  16. Network Wind Power Over the Pacific Northwest. Progress Report, October 1979-September 1980.

    Energy Technology Data Exchange (ETDEWEB)

    Baker, Robert W.; Hewson, E. Wendell

    1980-10-01

    The research in FY80 is composed of six primary tasks. These tasks include data collection and analysis, wind flow studies around an operational wind turbine generator (WTG), kite anemometer calibration, wind flow analysis and prediction, the Klickitat County small wind energy conversion system (SWECS) program, and network wind power analysis. The data collection and analysis task consists of four sections, three of which deal with wind flow site surveys and the fourth with collecting and analyzing wind data from existing data stations. This report also includes an appendix which contains mean monthly wind speed data summaries, wind spectrum summaries, time series analysis plots, and high wind summaries.

  17. Wind energy

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    This chapter discusses the role wind energy may have in the energy future of the US. The topics discussed in the chapter include historical aspects of wind energy use, the wind energy resource, wind energy technology including intermediate-size and small wind turbines and intermittency of wind power, public attitudes toward wind power, and environmental, siting and land use issues

  18. Wind Vision: A New Era for Wind Power in the United States (Highlights); U.S. Department of Energy (DOE), NREL (National Renewable Energy Laboratory)

    Energy Technology Data Exchange (ETDEWEB)

    None

    2015-03-01

    This is a four-part Wind Vision project, consisting of Wind Vision Highlights, Executive Summary, a Full Report, and Appendix. The U.S. Department of Energy (DOE) Wind Program, in close cooperation with the wind industry, led a comprehensive analysis to evaluate future pathways for the wind industry. The Wind Vision report updates and expands upon the DOE's 2008 report, 20% Wind Energy by 2030, and defines the societal, environmental, and economic benefits of wind power in a scenario with wind energy supplying 10% of national end-use electricity demand by 2020, 20% by 2030, and 35% by 2050.

  19. Preliminary Assessment of Potential Avian Interactions at Four Proposed Wind Energy Facilities on Vandenberg Air Force Base, California

    Energy Technology Data Exchange (ETDEWEB)

    2004-08-01

    The United States Air Force (USAF) is investigating whether to install wind turbines to provide a supplemental source of electricity at Vandenberg Air Force Base (VAFB) near Lompoc, California. As part of that investigation, VAFB sought assistance from the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) to provide a preliminary characterization of the potential risk to wildlife resources (mainly birds and bats) from wind turbine installations. With wind power development expanding throughout North America and Europe, concerns have surfaced over the number of bird fatalities associated with wind turbines. Guidelines developed for the wind industry by the National Wind Coordinating Committee (NWCC) recommend assessing potential impacts to birds, bats, and other potentially sensitive resources before construction. The primary purpose of an assessment is to identify potential conflicts with sensitive resources, to assist developers with identifying their permitting needs, and to develop strategies to avoid impacts or to mitigate their effects. This report provides a preliminary (Phase I) biological assessment of potential impacts to birds and bats that might result from construction and operation of the proposed wind energy facilities on VAFB.

  20. User's manual for rocket combustor interactive design (ROCCID) and analysis computer program. Volume 2: Appendixes A-K

    Science.gov (United States)

    Muss, J. A.; Nguyen, T. V.; Johnson, C. W.

    1991-01-01

    The appendices A-K to the user's manual for the rocket combustor interactive design (ROCCID) computer program are presented. This includes installation instructions, flow charts, subroutine model documentation, and sample output files. The ROCCID program, written in Fortran 77, provides a standardized methodology using state of the art codes and procedures for the analysis of a liquid rocket engine combustor's steady state combustion performance and combustion stability. The ROCCID is currently capable of analyzing mixed element injector patterns containing impinging like doublet or unlike triplet, showerhead, shear coaxial and swirl coaxial elements as long as only one element type exists in each injector core, baffle, or barrier zone. Real propellant properties of oxygen, hydrogen, methane, propane, and RP-1 are included in ROCCID. The properties of other propellants can be easily added. The analysis models in ROCCID can account for the influences of acoustic cavities, helmholtz resonators, and radial thrust chamber baffles on combustion stability. ROCCID also contains the logic to interactively create a combustor design which meets input performance and stability goals. A preliminary design results from the application of historical correlations to the input design requirements. The steady state performance and combustion stability of this design is evaluated using the analysis models, and ROCCID guides the user as to the design changes required to satisfy the user's performance and stability goals, including the design of stability aids. Output from ROCCID includes a formatted input file for the standardized JANNAF engine performance prediction procedure.

  1. Nonlinear Controllers Based on Exact Feedback Linearization for Series-Compensated DFIG-Based Wind Parks to Mitigate Sub-Synchronous Control Interaction

    Directory of Open Access Journals (Sweden)

    Penghan Li

    2017-08-01

    Full Text Available The increasing penetration of wind power in the grid has driven the integration of wind farms with power systems that are series-compensated to enhance power transfer capability and dynamic stability. This may lead to sub-synchronous control interaction (SSCI problems in series-compensated doubly-fed induction generator (DFIG-based wind farms. To mitigate SSCI, nonlinear controllers based on exact feedback linearization (EFL are proposed in this paper. Before deriving the control laws, the exact feedback linearizability of the studied system is scrutinized. Frequency scanning analysis is employed to test the designed EFL controllers. Moreover, the performance of the EFL controllers is compared to that of classical proportional-integral (PI controllers. A series-compensated 100 MW DFIG-based wind park is utilized to assess the performance of the designed controllers through the alleviation of sub-synchronous resonance. Analyses of the studied system reveal that the resistance is negative under sub-synchronous frequency conditions, whereas the reactance becomes negative at approximately 44 Hz. The designed EFL controllers effectively alleviate SSCI and result in positive reactance and resistance values within the whole sub-synchronous frequency range. The results from the frequency scanning method are also validated through the time domain simulation and the eigenvalue analysis.

  2. Appendix A : literature review.

    Science.gov (United States)

    2013-03-01

    This appendix contains a review of the literature and other background information : germane to the experimental and analytical research presented in subsequent appendices. Table : 1 lists the sections and topics contained in this appendix and those ...

  3. Wind energy

    International Nuclear Information System (INIS)

    Portilla S, L.A.

    1995-01-01

    The wind energy or eolic energy is a consequence of solar energy, the one which is absorbed by the atmosphere and is transformed into energy of movement of large bulks of air. In this process the atmosphere acts as the filter to the solar radiation and demotes the ultraviolet beams that result fatal to life in the Earth. The ionosphere is the most external cap and this is ionized by means of absorption process of ultraviolet radiation arising to the Sun. The atmosphere also acts as a trap to the infrared radiation, it that results from the continual process of energetic degradation. In this way, the interaction between Earth - Atmospheres, is behaved as a great greenhouse, maintaining the constant temperatures, including in the dark nights. Processes as the natural convection (that occur by the thermodynamic phenomenon), equatorial calmness, trade winds and against trade winds and global distribution of the air currents are described. The other hand, techniques as the transformation of the wind into energy and its parameters also are shown

  4. TWO REGIMES OF INTERACTION OF A HOT JUPITER’S ESCAPING ATMOSPHERE WITH THE STELLAR WIND AND GENERATION OF ENERGIZED ATOMIC HYDROGEN CORONA

    International Nuclear Information System (INIS)

    Shaikhislamov, I. F.; Prokopov, P. A.; Berezutsky, A. G.; Zakharov, Yu. P.; Posukh, V. G.; Khodachenko, M. L.; Lammer, H.; Kislyakova, K. G.; Fossati, L.; Johnstone, C. P.

    2016-01-01

    The interaction of escaping the upper atmosphere of a hydrogen-rich non-magnetized analog of HD 209458b with a stellar wind (SW) of its host G-type star at different orbital distances is simulated with a 2D axisymmetric multi-fluid hydrodynamic (HD) model. A realistic Sun-like spectrum of X-ray and ultraviolet radiation, which ionizes and heats the planetary atmosphere, together with hydrogen photochemistry, as well as stellar-planetary tidal interaction are taken into account to generate self-consistently an atmospheric HD outflow. Two different regimes of the planetary and SW interaction have been modeled. These are: (1) the “ captured by the star ” regime, when the tidal force and pressure gradient drive the planetary material beyond the Roche lobe toward the star, and (2) the “ blown by the wind ” regime, when sufficiently strong SW confines the escaping planetary atmosphere and channels it into the tail. The model simulates in detail the HD interaction between the planetary atoms, protons and the SW, as well as the production of energetic neutral atoms (ENAs) around the planet due to charge exchange between planetary atoms and stellar protons. The revealed location and shape of the ENA cloud, either as a paraboloid shell between the ionopause and bowshock (for the “ blown by the wind ” regime), or a turbulent layer at the contact boundary between the planetary stream and SW (for the “ captured by the star ” regime) are of importance for the interpretation of Ly α absorption features in exoplanetary transit spectra and characterization of the plasma environments.

  5. TWO REGIMES OF INTERACTION OF A HOT JUPITER’S ESCAPING ATMOSPHERE WITH THE STELLAR WIND AND GENERATION OF ENERGIZED ATOMIC HYDROGEN CORONA

    Energy Technology Data Exchange (ETDEWEB)

    Shaikhislamov, I. F.; Prokopov, P. A.; Berezutsky, A. G.; Zakharov, Yu. P.; Posukh, V. G. [Institute of Laser Physics SB RAS, Novosibirsk (Russian Federation); Khodachenko, M. L.; Lammer, H.; Kislyakova, K. G.; Fossati, L. [Space Research Institute, Austrian Acad. Sci., Graz (Austria); Johnstone, C. P., E-mail: maxim.khodachenko@oeaw.ac.at [Department of Astrophysics, University of Vienna, Vienna (Austria)

    2016-12-01

    The interaction of escaping the upper atmosphere of a hydrogen-rich non-magnetized analog of HD 209458b with a stellar wind (SW) of its host G-type star at different orbital distances is simulated with a 2D axisymmetric multi-fluid hydrodynamic (HD) model. A realistic Sun-like spectrum of X-ray and ultraviolet radiation, which ionizes and heats the planetary atmosphere, together with hydrogen photochemistry, as well as stellar-planetary tidal interaction are taken into account to generate self-consistently an atmospheric HD outflow. Two different regimes of the planetary and SW interaction have been modeled. These are: (1) the “ captured by the star ” regime, when the tidal force and pressure gradient drive the planetary material beyond the Roche lobe toward the star, and (2) the “ blown by the wind ” regime, when sufficiently strong SW confines the escaping planetary atmosphere and channels it into the tail. The model simulates in detail the HD interaction between the planetary atoms, protons and the SW, as well as the production of energetic neutral atoms (ENAs) around the planet due to charge exchange between planetary atoms and stellar protons. The revealed location and shape of the ENA cloud, either as a paraboloid shell between the ionopause and bowshock (for the “ blown by the wind ” regime), or a turbulent layer at the contact boundary between the planetary stream and SW (for the “ captured by the star ” regime) are of importance for the interpretation of Ly α absorption features in exoplanetary transit spectra and characterization of the plasma environments.

  6. 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...... 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...... conditions. So, a new aeroelastic blade model has been derived, which includes important features of large wind turbines, yet simple enough to be suitable for analytical analysis and control design....

  7. The Effect of Combined Magnetic Geometries on Thermally Driven Winds. I. Interaction of Dipolar and Quadrupolar Fields

    Energy Technology Data Exchange (ETDEWEB)

    Finley, Adam J.; Matt, Sean P., E-mail: af472@exeter.ac.uk [University of Exeter (UK), Department of Physics and Astronomy, Stoker Road, Devon, Exeter, EX4 4QL (United Kingdom)

    2017-08-10

    Cool stars with outer convective envelopes are observed to have magnetic fields with a variety of geometries, which on large scales are dominated by a combination of the lowest-order fields such as the dipole, quadrupole, and octupole modes. Magnetized stellar wind outflows are primarily responsible for the loss of angular momentum from these objects during the main sequence. Previous works have shown the reduced effectiveness of the stellar wind braking mechanism with increasingly complex but singular magnetic field geometries. In this paper, we quantify the impact of mixed dipolar and quadrupolar fields on the spin-down torque using 50 MHD simulations with mixed fields, along with 10 each of the pure geometries. The simulated winds include a wide range of magnetic field strength and reside in the slow-rotator regime. We find that the stellar wind braking torque from our combined geometry cases is well described by a broken power-law behavior, where the torque scaling with field strength can be predicted by the dipole component alone or the quadrupolar scaling utilizing the total field strength. The simulation results can be scaled and apply to all main-sequence cool stars. For solar parameters, the lowest-order component of the field (dipole in this paper) is the most significant in determining the angular momentum loss.

  8. Identifying space for offshore wind energy in the North Sea. Consequences of scenario calculations for interactions with other marine uses

    NARCIS (Netherlands)

    Jongbloed, R.H.; Wal, van der J.T.; Lindeboom, H.J.

    2014-01-01

    The increasing demand for renewable energy drives the development of offshore wind energy (OWE) leading to competing claims with other human and nature related uses of the North Sea. This paper investigates possibilities to identify space for new OWE while minimising effects on other uses. An

  9. Transient Studies in Large Offshore Wind Farms, Tak-ing Into Account Network/Circuit Breaker Interaction

    DEFF Research Database (Denmark)

    Glasdam, Jakob; Bak, Claus Leth; Hjerrild, Jesper

    2011-01-01

    Switching overvoltages (SOV) are considered a possible source of experienced component failures in existing offshore wind farms (OWFs). The inclusion of sufficiently accurate and validated models of the main components in the OWF in the simulation tool is therefore an important issue in order to ...

  10. I parchi eolici: la complessa interazione tra natura, uomo e tecnologia - The wind farms: the complex interaction among nature, man and technology

    Directory of Open Access Journals (Sweden)

    Massimiliano Masullo

    2015-10-01

    Full Text Available Sin dai tempi antichi l’uomo ha costruito macchine che, sfruttando l’energia del vento, lo hanno aiutato a nutrire se stesso, la terra e a svolgere lavorazioni complesse. Con la scoperta dell’elettricità la funzione di queste macchine è cambiata radicalmente. Negli ultimi venti anni, politiche d'incentivazione hanno portato allo sviluppo di impianti eolici ed alla loro diffusione sul territorio, determinando una interazione sempre più intensa fra turbine eoliche, ambiente circostante ed uomo. Questo articolo presentata una rassegna dei principali fattori che determinano o modificano la percezione dell’impatto che queste macchine hanno sull’uomo e sull’ambiente circostante. ------ Since ancient times the man has built machines which exploiting the energy of the wind have helped to feed himself, the land and carry out complex operations. With the discovery of electricity the function of these machines is changed radically. In the last twenty years, incentive policies have led to the development of wind farms and their diffusion over the territory, resulting in a more intense interaction between wind turbines, environment and man. This article presents a review of the main factors that determine or affect the perception of the impact that these machines have on humans and the surrounding environment.

  11. Modeling and Observing the Role of Wind-Waves in Lake-Climate Interactions on Titan using the T104 Flyby of Kraken Mare

    Science.gov (United States)

    Hayes, A. G., Jr.; Lorenz, R. D.; Zebker, H. A.; Donelan, M. A.; Karatekin, O.; Mastrogiuseppe, M., Sr.; Le Gall, A. A.; Hofgartner, J. D.; Encrenaz, P.; Poggiali, V.

    2014-12-01

    Oceanography is no longer just an Earth Science. Standing bodies of liquid that interact with both atmospheric and surface reservoirs are known to exist on Titan, and are thought to have existed on early Mars. The exchange of heat, moisture, and momentum between lakes/seas and the atmosphere are of fundamental importance to the hydrologic systems of all three bodies. The generation and propagation of wind-waves, and their consequent shoreline erosion, are key factors in air-sea-surface exchange. Titan, in particular, offers a laboratory in which to understand these processes at a more fundamental level. Much of the parameterization for wave models on Earth are empirical, despite laboratory studies that have demonstrated wave growth depends on both gravity and fluid properties. Titan's exotic environment ensures that even rudimentary measurements of wave generation will provide valuable data to anchor physical models. Furthermore, in the presence of wind waves, Cassini can be used as an anemometer to measure wind speeds over hydrocarbon liquids. Herein, we will report on the results of the Aug 21st altimetry observation over Titan's largest sea, Kraken Mare, and interpret them in the context of wave activity and composition (from passive radiometry). On Earth, it is rare to observe a body of water whose surface is not disturbed by some form of wave activity. On Titan, Cassini observations through the end of its Equinox Mission in Dec 2010 showed no indication of waves. These observations are intriguing given the predominance of aeolian features at equatorial latitudes and have been attributed to the light winds predicted during the Titan winter. More recently, however, the previous series of upper limits and non-detections are giving way to indications that the expected freshening of winds in northern summer may be causing sporadic ruffling of the sea surfaces. Specifically, apparent sunglints offset from the geometric specular point has been observed by VIMS in

  12. Grid-Free 2D Plasma Simulations of the Complex Interaction Between the Solar Wind and Small, Near-Earth Asteroids

    Science.gov (United States)

    Zimmerman, M. I.; Farrell, W. M.; Poppe, A. R.

    2014-01-01

    We present results from a new grid-free 2D plasma simulation code applied to a small, unmagnetized body immersed in the streaming solar wind plasma. The body was purposely modeled as an irregular shape in order to examine photoemission and solar wind plasma flow in high detail on the dayside, night-side, terminator and surface-depressed 'pocket' regions. Our objective is to examine the overall morphology of the various plasma interaction regions that form around a small body like a small near-Earth asteroid (NEA). We find that the object obstructs the solar wind flow and creates a trailing wake region downstream, which involves the interplay between surface charging and ambipolar plasma expansion. Photoemission is modeled as a steady outflow of electrons from illuminated portions of the surface, and under direct illumination the surface forms a non-monotonic or ''double-sheath'' electric potential upstream of the body, which is important for understanding trajectories and equilibria of lofted dust grains in the presence of a complex asteroid geometry. The largest electric fields are found at the terminators, where ambipolar plasma expansion in the body-sized night-side wake merges seamlessly with the thin photoelectric sheath on the dayside. The pocket regions are found to be especially complex, with nearby sunlit regions of positive potential electrically connected to unlit negative potentials and forming adjacent natural electric dipoles. For objects near the surface, we find electrical dissipation times (through collection of local environmental solar wind currents) that vary over at least 5 orders of magnitude: from 39 Micro(s) inside the near-surface photoelectron cloud under direct sunlight to less than 1 s inside the particle-depleted night-side wake and shadowed pocket regions

  13. Wind Energy

    International Nuclear Information System (INIS)

    Rodriguez D, J.M.

    1998-01-01

    The general theory of the wind energy conversion systems is presented. The availability of the wind resource in Colombia and the ranges of the speed of the wind in those which is possible economically to use the wind turbines are described. It is continued with a description of the principal technological characteristics of the wind turbines and are split into wind power and wind-powered pumps; and its use in large quantities grouped in wind farms or in autonomous systems. Finally, its costs and its environmental impact are presented

  14. Duplication of Vermiform Appendix.

    Science.gov (United States)

    Bhat, Gulzar Ahmad; Reshi, Tarooq Ahmad; Rashid, Asiya

    2016-02-01

    The vermiform appendix is a tubular, narrow, worm-shaped part of the alimentary canal that lies near the ileocecal junction and communicates with the caecum. Duplication of the vermiform appendix is rare, with a reported incidence of 0.004 %. Till now, fewer than 100 cases have been reported. We present a case of an 8-year-old male child with duplex appendix who presented to the emergency department of our institution with features of acute appendicitis.

  15. Relationship between solar wind corotating interaction regions and the phasing and intensity of Saturn kilometric radiation bursts

    Directory of Open Access Journals (Sweden)

    S. V. Badman

    2008-11-01

    Full Text Available Voyager spacecraft measurements of Saturn kilometric radiation (SKR identified two features of these radio emissions: that they pulse at a period close to the planetary rotation period, and that the emitted intensity is correlated with the solar wind dynamic pressure (Desch and Kaiser, 1981; Desch, 1982; Desch and Rucker, 1983. In this study the inter-relation between the intensity and the pulsing of the SKR is analysed using Cassini spacecraft measurements of the interplanetary medium and SKR over the interval encompassing Cassini's approach to Saturn, and the first extended orbit. Cassini Plasma Spectrometer ion data were only available for a subset of the dates of interest, so the interplanetary conditions were studied primarily using the near-continuously available magnetic field data, augmented by the ion moment data when available. Intense SKR bursts were identified when solar wind compressions arrived at Saturn. The intensity of subsequent emissions detected by Cassini during the compression intervals was variable, sometimes remaining intense for several planetary rotations, sometimes dimming and rarely disappearing. The timings of the initial intense SKR peaks were sometimes independent of the long-term pulsing behaviour identified in the SKR data. Overall, however, the pulsing of the SKR peaks during the disturbed intervals was not significantly altered relative to that during non-compression intervals.

  16. Relationship between solar wind corotating interaction regions and the phasing and intensity of Saturn kilometric radiation bursts

    Directory of Open Access Journals (Sweden)

    S. V. Badman

    2008-11-01

    Full Text Available Voyager spacecraft measurements of Saturn kilometric radiation (SKR identified two features of these radio emissions: that they pulse at a period close to the planetary rotation period, and that the emitted intensity is correlated with the solar wind dynamic pressure (Desch and Kaiser, 1981; Desch, 1982; Desch and Rucker, 1983. In this study the inter-relation between the intensity and the pulsing of the SKR is analysed using Cassini spacecraft measurements of the interplanetary medium and SKR over the interval encompassing Cassini's approach to Saturn, and the first extended orbit. Cassini Plasma Spectrometer ion data were only available for a subset of the dates of interest, so the interplanetary conditions were studied primarily using the near-continuously available magnetic field data, augmented by the ion moment data when available. Intense SKR bursts were identified when solar wind compressions arrived at Saturn. The intensity of subsequent emissions detected by Cassini during the compression intervals was variable, sometimes remaining intense for several planetary rotations, sometimes dimming and rarely disappearing. The timings of the initial intense SKR peaks were sometimes independent of the long-term pulsing behaviour identified in the SKR data. Overall, however, the pulsing of the SKR peaks during the disturbed intervals was not significantly altered relative to that during non-compression intervals.

  17. Self-organization of large-scale ULF electromagnetic wave structures in their interaction with nonuniform zonal winds in the ionospheric E region

    International Nuclear Information System (INIS)

    Aburjania, G. D.; Chargazia, Kh. Z.

    2011-01-01

    A study is made of the generation and subsequent linear and nonlinear evolution of ultralow-frequency planetary electromagnetic waves in the E region of a dissipative ionosphere in the presence of a nonuniform zonal wind (a sheared flow). Hall currents flowing in the E region and such permanent global factors as the spatial nonuniformity of the geomagnetic field and of the normal component of the Earth’s angular velocity give rise to fast and slow planetary-scale electromagnetic waves. The efficiency of the linear amplification of planetary electromagnetic waves in their interaction with a nonuniform zonal wind is analyzed. When there are sheared flows, the operators of linear problems are non-self-conjugate and the corresponding eigenfunctions are nonorthogonal, so the canonical modal approach is poorly suited for studying such motions and it is necessary to utilize the so-called nonmodal mathematical analysis. It is shown that, in the linear evolutionary stage, planetary electromagnetic waves efficiently extract energy from the sheared flow, thereby substantially increasing their amplitude and, accordingly, energy. The criterion for instability of a sheared flow in an ionospheric medium is derived. As the shear instability develops and the perturbation amplitude grows, a nonlinear self-localization mechanism comes into play and the process ends with the self-organization of nonlinear, highly localized, solitary vortex structures. The system thus acquires a new degree of freedom, thereby providing a new way for the perturbation to evolve in a medium with a sheared flow. Depending on the shape of the sheared flow velocity profile, nonlinear structures can be either purely monopole vortices or vortex streets against the background of the zonal wind. The accumulation of such vortices can lead to a strongly turbulent state in an ionospheric medium.

  18. Design and Implement a Digital H∞ Robust Controller for a MW-Class PMSG-Based Grid-Interactive Wind Energy Conversion System

    Directory of Open Access Journals (Sweden)

    Tomonobu Senjyu

    2013-04-01

    Full Text Available A digital H∞ controller for a permanent magnet synchronous generator (PMSG based wind energy conversion system (WECS is presented. Wind energy is an uncertain fluctuating resource which requires a tight control management. So, it is still an exigent task for the control design engineers. The conventional proportional-integral (PI control is not ideal during high turbulence wind velocities, and the nonlinear behavior of the power converters. These are raising interest towards the robust control concepts. The robust design is to find a controller, for a given system, such that the closed-loop system becomes robust that assurance high-integrity and fault tolerant control system, robust H∞ control theory has befallen a standard design method of choice over the past two decades in industrial control applications. The robust H∞ control theory is also gaining eminence in the WECS. Due to the implementation complexity for the continuous H∞ controller, and availability of the high speedy micro-controllers, the design of a sample-data or a digital H∞ controller is very important for the realistic implementation. But there isn’t a single research to evaluate the performance of the digital H∞ controller for the WECS. In this paper, the proposed digital H∞ controller schemes comprise for the both generator and grid interactive power converters, and the control performances are compared with the conventional PI controller and the fuzzy controller. Simulation results confirm the efficacy of the proposed method Energies 2013, 6 2085 which are ensured the WECS stabilities, mitigate shaft stress, and improving the DC-link voltage and output power qualities.

  19. Design and Implement a Digital H{sub {infinity}}Robust Controller for a MW-Class PMSG-Based Grid-Interactive Wind Energy Conversion System

    Energy Technology Data Exchange (ETDEWEB)

    Howlander, Abdul Motin [Faculty of Engineering, Univ. of the Ryukyus, Okinawa (Japan); Urasaki, Naomitsu [Faculty of Engineering, Univ. of the Ryukyus, Okinawa (Japan); Yona, Atsushi [Faculty of Engineering, Univ. of the Ryukyus, Okinawa (Japan); Senjyu, Tomonobu [Faculty of Engineering, Univ. of the Ryukyus, Okinawa (Japan); Saber, Ahmed Yousuf [Operation Technology, Irvine, CA (United States)

    2013-04-15

    A digital H{sub {infinity}}controller for a permanent magnet synchronous generator (PMSG) based wind energy conversion system (WECS) is presented. Wind energy is an uncertain fluctuating resource which requires a tight control management. So, it is still an exigent task for the control design engineers. The conventional proportional-integral (PI) control is not ideal during high turbulence wind velocities, and the nonlinear behavior of the power converters. These are raising interest towards the robust control concepts. The robust design is to find a controller, for a given system, such that the closed-loop system becomes robust that assurance high-integrity and fault tolerant control system, robust H{sub {infinity}}control theory has befallen a standard design method of choice over the past two decades in industrial control applications. The robust H{sub {infinity}}control theory is also gaining eminence in the WECS. Due to the implementation complexity for the continuous H{sub {infinity}}controller, and availability of the high speedy micro-controllers, the design of a sample-data or a digital H{sub {infinity}}controller is very important for the realistic implementation. But there isn’t a single research to evaluate the performance of the digital H{sub {infinity}}controller for the WECS. In this paper, the proposed digital H{sub {infinity}}controller schemes comprise for the both generator and grid interactive power converters, and the control performances are compared with the conventional PI controller and the fuzzy controller. Simulation results confirm the efficacy of the proposed method Energies 2013, 6 2085 which are ensured the WECS stabilities, mitigate shaft stress, and improving the DC-link voltage and output power qualities.

  20. Offshore wind resources at Danish measurement sites

    Energy Technology Data Exchange (ETDEWEB)

    Barthelmie, R.J.; Courtney, M.S.; Lange, B.; Nielsen, M.; Sempreviva, A.M. [Risoe National Lab., Dept. of Wind Energy and Atmospheric Physics, Roskilde (Denmark); Svenson, J.; Olsen, F. [SEAS, Haslev (Denmark); Christensen, T. [Elsamprojekt, Fredericia (Denmark)

    1999-03-01

    In order to characterise wind and turbulence characteristics at prospective offshore wind energy sites, meteorological observations from a number of purpose-built offshore monitoring sites have been analyzed and compared with long wind speed time series. New analyses have been conducted on the data sets focussing on meteorology, turbulence, extreme winds and wind and wave interactions. Relationships between wind speed, turbulence and fetch are highly complex. Minimum turbulence intensity offshore is associated with wind speeds of about 12 m/s. At lower wind speeds, stability effects are important while at higher winds speeds wind and wave interactions appear to dominate. On average, turbulence intensity offshore at 48 m height is approximately 0.08 if no coastal effects are present. However, the effect of the coastal discontinuity persists in wind speed and turbulence characteristics for considerable distances offshore. The majority of the adjustment of appears to occur within 20 km of the coast. (au)

  1. Large-Scale Uncertainty and Error Analysis for Time-dependent Fluid/Structure Interactions in Wind Turbine Applications

    Energy Technology Data Exchange (ETDEWEB)

    Alonso, Juan J. [Stanford University; Iaccarino, Gianluca [Stanford University

    2013-08-25

    solution to the long-time integration problem of spectral chaos approaches; 4. A rigorous methodology to account for aleatory and epistemic uncertainties, to emphasize the most important variables via dimension reduction and dimension-adaptive refinement, and to support fusion with experimental data using Bayesian inference; 5. The application of novel methodologies to time-dependent reliability studies in wind turbine applications including a number of efforts relating to the uncertainty quantification in vertical-axis wind turbine applications. In this report, we summarize all accomplishments in the project (during the time period specified) focusing on advances in UQ algorithms and deployment efforts to the wind turbine application area. Detailed publications in each of these areas have also been completed and are available from the respective conference proceedings and journals as detailed in a later section.

  2. Summary of wind data from nuclear power plant sites. [USA

    Energy Technology Data Exchange (ETDEWEB)

    Verholek, M. G.

    1977-03-01

    A summary of wind data from nuclear power plant sites is presented. National Weather Service archives are an immediately obvious source of wind data, but additional data sources are also available. Utility companies proposing to build nuclear power plants are required to establish on-site meteorological monitoring programs that include towers for collecting wind and temperature data for use in environmental impact assessments. These data are available for more than one hundred planned or operating nuclear power plant sites. A list of the sites, by state, is provided in Appendix A, while Appendix B contains an alphabetical list of the sites. This site wind data provides a valuable addition to the existing NWS data sets, and significantly enlarges the multilevel data presently available. The wind data published through the NRC is assembled and assessed here in order to provide a supplement to existing data sets.

  3. Wind energy options in the Netherlands

    International Nuclear Information System (INIS)

    Arkesteijn, L.A.G.; Havinga, R.J.

    1992-07-01

    Next to a study of the title subject attention is paid to the quantification of the wind energy potential and the conditions under which such potentials can be realized. The options are influenced by technical-economical, planning and socio-political factors, which are summarized in appendix 1 and discussed in chapter three. Results of interviews with experts in the field of wind energy can be found in appendix 2. Based on the impacts on the wind energy potential four wind energy development scenarios are compared in chapter four. The reference scenario is based on the present wind energy policy in the Netherlands. The other three scenarios are the Price-scenario (higher societal appreciation of electricity generated by wind power), the Site-scenario (matters of site selection and planning), and a Combined-scenario (combination of the Price- and the Site-scenario). For each scenario potential estimations were made for the years 2000, 2010, 2015, and restricted estimations for the year 2025. It is concluded that within 25 years 2,500 MW wind power can be realized on land and 6,000 MW on water. The main problems for the location on land and inland waterways are the planning restrictions, and for sea locations the limiting factor is the high cost price. Recommendations to the Dutch government to realize the potentials concern the facts that social advantages of wind energy should be part of the price of the energy, more sites should be made available for the application of wind energy, more research has to be carried out on the possibility of locating wind power generating systems at sea, and the social basis for wind energy should be maintained and even increased. 18 figs., 5 app., 47 refs

  4. Noise and noise disturbances from wind power plants - Tests with interactive control of sound parameters for more comfortable and less perceptible sounds; Buller och bullerstoerningar fraan vindkraftverk - Foersoek med interaktiv styrning av ljudparametrar foer behagligare och mindre maerkbara ljud

    Energy Technology Data Exchange (ETDEWEB)

    Persson-Waye, K.; Oehrstroem, E.; Bjoerkman, M.; Agge, A. [Goeteborg Univ. (Sweden). Dept. of Environmental Medicine

    2001-12-01

    In experimental pilot studies, a methodology has been worked out for interactively varying sound parameters in wind power plants. In the tests, 24 persons varied the center frequency of different band-widths, the frequency of a sinus-tone and the amplitude-modulation of a sinus-tone in order to create as comfortable a sound as possible. The variations build on the noise from the two wind turbines Bonus and Wind World. The variations were performed with a constant dba level. The results showed that the majority preferred a low-frequency tone (94 Hz and 115 Hz for Wind World and Bonus, respectively). The mean of the most comfortable amplitude-modulation varied between 18 and 22 Hz, depending on the ground frequency. The mean of the center-frequency for the different band-widths varied from 785 to 1104 Hz. In order to study the influence of the wind velocity on the acoustic character of the noise, a long-time measurement program has been performed. A remotely controlled system has been developed, where wind velocity, wind direction, temperature and humidity are registered simultaneously with the noise. Long-time registrations have been performed for four different wing turbines.

  5. Insights into Airframe Aerodynamics and Rotor-on-Wing Interactions from a 0.25-Scale Tiltrotor Wind Tunnel Model

    National Research Council Canada - National Science Library

    Young, L. A; Lillie, D; McCluer, M; Yamauchi, G. K; Derby, M. R

    2002-01-01

    A recent experimental investigation into tiltrotor aerodynamics and acoustics has resulted in the acquisition of a set of data related to tiltrotor airframe aerodynamics and rotor and wing interactional aerodynamics...

  6. Simulated solar wind plasma interaction with the Martian exosphere: influence of the solar EUV flux on the bow shock and the magnetic pile-up boundary

    Directory of Open Access Journals (Sweden)

    R. Modolo

    2006-12-01

    Full Text Available The solar wind plasma interaction with the Martian exosphere is investigated by means of 3-D multi-species hybrid simulations. The influence of the solar EUV flux on the bow shock and the magnetic pile-up boundary is examined by comparing two simulations describing the two extreme states of the solar cycle. The hybrid formalism allows a kinetic description of each ions species and a fluid description of electrons. The ionization processes (photoionization, electron impact and charge exchange are included self-consistently in the model where the production rate is computed locally, separately for each ionization act and for each neutral species. The results of simulations are in a reasonable agreement with the observations made by Phobos 2 and Mars Global Surveyor spacecraft. The position of the bow shock and the magnetic pile-up boundary is weakly dependent of the solar EUV flux. The motional electric field creates strong asymmetries for the two plasma boundaries.

  7. AGAINST THE WIND: RADIO LIGHT CURVES OF TYPE IA SUPERNOVAE INTERACTING WITH LOW-DENSITY CIRCUMSTELLAR SHELLS

    International Nuclear Information System (INIS)

    Harris, Chelsea E.; Nugent, Peter E.; Kasen, Daniel N.

    2016-01-01

    For decades a wide variety of observations spanning the radio through optical and on to the X-ray have attempted to uncover signs of type Ia supernovae (SNe Ia) interacting with a circumstellar medium (CSM). The goal of these studies is to constrain the nature of the hypothesized SN Ia mass-donor companion. A continuous CSM is typically assumed when interpreting observations of interaction. However, while such models have been successfully applied to core-collapse SNe, the assumption of continuity may not be accurate for SNe Ia, because shells of CSM could be formed by pre-supernova eruptions (novae). In this work, we model the interaction of SNe with a spherical, low-density, finite-extent CSM and create a suite of synthetic radio synchrotron light curves. We find that CSM shells produce sharply peaked light curves. We also identify a fiducial set of models that obey a common evolution and can be used to generate radio light curves for an interaction with an arbitrary shell. The relations obeyed by the fiducial models can be used to deduce CSM properties from radio observations; we demonstrate this by applying them to the nondetections of SN 2011fe and SN 2014J. Finally, we explore a multiple shell CSM configuration and describe its more complicated dynamics and the resultant radio light curves.

  8. AGAINST THE WIND: RADIO LIGHT CURVES OF TYPE IA SUPERNOVAE INTERACTING WITH LOW-DENSITY CIRCUMSTELLAR SHELLS

    Energy Technology Data Exchange (ETDEWEB)

    Harris, Chelsea E.; Nugent, Peter E.; Kasen, Daniel N., E-mail: chelseaharris@berkeley.edu [Astronomy Department, University of California Berkeley, Berkeley, CA (United States)

    2016-06-01

    For decades a wide variety of observations spanning the radio through optical and on to the X-ray have attempted to uncover signs of type Ia supernovae (SNe Ia) interacting with a circumstellar medium (CSM). The goal of these studies is to constrain the nature of the hypothesized SN Ia mass-donor companion. A continuous CSM is typically assumed when interpreting observations of interaction. However, while such models have been successfully applied to core-collapse SNe, the assumption of continuity may not be accurate for SNe Ia, because shells of CSM could be formed by pre-supernova eruptions (novae). In this work, we model the interaction of SNe with a spherical, low-density, finite-extent CSM and create a suite of synthetic radio synchrotron light curves. We find that CSM shells produce sharply peaked light curves. We also identify a fiducial set of models that obey a common evolution and can be used to generate radio light curves for an interaction with an arbitrary shell. The relations obeyed by the fiducial models can be used to deduce CSM properties from radio observations; we demonstrate this by applying them to the nondetections of SN 2011fe and SN 2014J. Finally, we explore a multiple shell CSM configuration and describe its more complicated dynamics and the resultant radio light curves.

  9. 2008 WIND TECHNOLOGIES MARKET REPORT

    Energy Technology Data Exchange (ETDEWEB)

    Wiser, Ryan H.; Bolinger, Mark; Barbose, G.; Mills, A.; Rosa, A.; Porter, K.; Fink, S.; Tegen, S.; Musial, W.; Oteri, F.; Heimiller, D.; Rberts, B.; Belyeu, K.; Stimmel, R.

    2009-07-15

    domestic wind power market, including federal and state policy drivers, transmission issues, and grid integration. Finally, the report concludes with a preview of possible near- to medium-term market developments. This version of the Annual Report updates data presented in the previous editions, while highlighting key trends and important new developments from 2008. New to this edition is an executive summary of the report and an expanded final section on near- to medium-term market development. The report concentrates on larger-scale wind applications, defined here as individual turbines or projects that exceed 50 kW in size. The U.S. wind power sector is multifaceted, however, and also includes smaller, customer-sited wind turbines used to power the needs of residences, farms, and businesses. Data on these applications are not the focus of this report, though a brief discussion on Distributed Wind Power is provided on page 4. Much of the data included in this report were compiled by Berkeley Lab, and come from a variety of sources, including the American Wind Energy Association (AWEA), the Energy Information Administration (EIA), and the Federal Energy Regulatory Commission (FERC). The Appendix provides a summary of the many data sources used in the report. Data on 2008 wind capacity additions in the United States are based on information provided by AWEA; some minor adjustments to those data may be expected. In other cases, the data shown here represent only a sample of actual wind projects installed in the United States; furthermore, the data vary in quality. As such, emphasis should be placed on overall trends, rather than on individual data points. Finally, each section of this document focuses on historical market information, with an emphasis on 2008; with the exception of the final section, the report does not seek to forecast future trends.

  10. LIDAR Wind Speed Measurements of Evolving Wind Fields

    Energy Technology Data Exchange (ETDEWEB)

    Simley, E.; Pao, L. Y.

    2012-07-01

    Light Detection and Ranging (LIDAR) systems are able to measure the speed of incoming wind before it interacts with a wind turbine rotor. These preview wind measurements can be used in feedforward control systems designed to reduce turbine loads. However, the degree to which such preview-based control techniques can reduce loads by reacting to turbulence depends on how accurately the incoming wind field can be measured. Past studies have assumed Taylor's frozen turbulence hypothesis, which implies that turbulence remains unchanged as it advects downwind at the mean wind speed. With Taylor's hypothesis applied, the only source of wind speed measurement error is distortion caused by the LIDAR. This study introduces wind evolution, characterized by the longitudinal coherence of the wind, to LIDAR measurement simulations to create a more realistic measurement model. A simple model of wind evolution is applied to a frozen wind field used in previous studies to investigate the effects of varying the intensity of wind evolution. LIDAR measurements are also evaluated with a large eddy simulation of a stable boundary layer provided by the National Center for Atmospheric Research. Simulation results show the combined effects of LIDAR errors and wind evolution for realistic turbine-mounted LIDAR measurement scenarios.

  11. Comments for the Cape Wind Associates, LLC, Horseshoe Shoal, Nantucket Sound (Offshore Renewable Energy Project/OCS Air Permit)

    Science.gov (United States)

    List of comments for the Cape Wind Associates, LLC, Horseshoe Shoal, Nantucket Sound (Offshore Renewable Energy Project/OCS Air Permit: Massachusetts Plan Approval including nonattainment NSR Appendix A requirements).

  12. An Appropriate Wind Model for Wind Integrated Power Systems Reliability Evaluation Considering Wind Speed Correlations

    Directory of Open Access Journals (Sweden)

    Rajesh Karki

    2013-02-01

    Full Text Available Adverse environmental impacts of carbon emissions are causing increasing concerns to the general public throughout the world. Electric energy generation from conventional energy sources is considered to be a major contributor to these harmful emissions. High emphasis is therefore being given to green alternatives of energy, such as wind and solar. Wind energy is being perceived as a promising alternative. This source of energy technology and its applications have undergone significant research and development over the past decade. As a result, many modern power systems include a significant portion of power generation from wind energy sources. The impact of wind generation on the overall system performance increases substantially as wind penetration in power systems continues to increase to relatively high levels. It becomes increasingly important to accurately model the wind behavior, the interaction with other wind sources and conventional sources, and incorporate the characteristics of the energy demand in order to carry out a realistic evaluation of system reliability. Power systems with high wind penetrations are often connected to multiple wind farms at different geographic locations. Wind speed correlations between the different wind farms largely affect the total wind power generation characteristics of such systems, and therefore should be an important parameter in the wind modeling process. This paper evaluates the effect of the correlation between multiple wind farms on the adequacy indices of wind-integrated systems. The paper also proposes a simple and appropriate probabilistic analytical model that incorporates wind correlations, and can be used for adequacy evaluation of multiple wind-integrated systems.

  13. Solar wind interaction with Mars Upper atmosphere: Results from the one-way coupling between the Multi-fluid MHD model and the M-TGCM model

    Science.gov (United States)

    Dong, C.; Bougher, S. W.; Ma, Y.; Toth, G.; Nagy, A. F.; Brain, D. A.; Najib, D.

    2012-12-01

    The study of the solar wind interaction with Mars upper atmosphere/ionosphere has triggered great interest in recent years. Among the large number of topics in this research area, the investigation of ion escape rates has become increasingly important due to its potential impact on the long-term evolution of Mars atmosphere (e.g., loss of water) over its history. In the present work, we adopt the 3D Mars neutral atmosphere profiles from the well-regarded Mars Thermospheric Global Circulation Model (M-TGCM) and one-way couple it with the 3D BATS-R-US Mars multi-fluid MHD model that solves separate momentum equations for each ion species. The M-TGCM model takes into account the effects of the solar cycle (solar minimum: F10.7=70 and solar maximum: F10.7=200 with equinox condition: Ls=0), allowing us to investigate the effects of the solar cycle on the Mars upper atmosphere ion escape by using a one-way coupling, i.e., the M-TGCM model outputs are used as inputs for the multi-fluid MHD model. A case for solar maximum with extremely high solar wind parameters is also investigated to estimate how high the escape flux can be for such an extreme case. Moreover, the ion escape flux along a satellite trajectory will be studied. This has the potential to provide predictions of ion escape rates for comparison to future data to be returned by the MAVEN mission (2012-2016). In order to make the code run more efficiently, we adopt a more appropriate grid structure compared to the one used previously. This new grid structure will benefit us to investigate the effects of some dynamic events (such as CME and dust storm) on the ion escape flux.

  14. Wind Speed Perception and Risk

    Science.gov (United States)

    Agdas, Duzgun; Webster, Gregory D.; Masters, Forrest J.

    2012-01-01

    Background How accurately do people perceive extreme wind speeds and how does that perception affect the perceived risk? Prior research on human–wind interaction has focused on comfort levels in urban settings or knock-down thresholds. No systematic experimental research has attempted to assess people's ability to estimate extreme wind speeds and perceptions of their associated risks. Method We exposed 76 people to 10, 20, 30, 40, 50, and 60 mph (4.5, 8.9, 13.4, 17.9, 22.3, and 26.8 m/s) winds in randomized orders and asked them to estimate wind speed and the corresponding risk they felt. Results Multilevel modeling showed that people were accurate at lower wind speeds but overestimated wind speeds at higher levels. Wind speed perceptions mediated the direct relationship between actual wind speeds and perceptions of risk (i.e., the greater the perceived wind speed, the greater the perceived risk). The number of tropical cyclones people had experienced moderated the strength of the actual–perceived wind speed relationship; consequently, mediation was stronger for people who had experienced fewer storms. Conclusion These findings provide a clearer understanding of wind and risk perception, which can aid development of public policy solutions toward communicating the severity and risks associated with natural disasters. PMID:23226230

  15. Wind speed perception and risk.

    Directory of Open Access Journals (Sweden)

    Duzgun Agdas

    Full Text Available BACKGROUND: How accurately do people perceive extreme wind speeds and how does that perception affect the perceived risk? Prior research on human-wind interaction has focused on comfort levels in urban settings or knock-down thresholds. No systematic experimental research has attempted to assess people's ability to estimate extreme wind speeds and perceptions of their associated risks. METHOD: We exposed 76 people to 10, 20, 30, 40, 50, and 60 mph (4.5, 8.9, 13.4, 17.9, 22.3, and 26.8 m/s winds in randomized orders and asked them to estimate wind speed and the corresponding risk they felt. RESULTS: Multilevel modeling showed that people were accurate at lower wind speeds but overestimated wind speeds at higher levels. Wind speed perceptions mediated the direct relationship between actual wind speeds and perceptions of risk (i.e., the greater the perceived wind speed, the greater the perceived risk. The number of tropical cyclones people had experienced moderated the strength of the actual-perceived wind speed relationship; consequently, mediation was stronger for people who had experienced fewer storms. CONCLUSION: These findings provide a clearer understanding of wind and risk perception, which can aid development of public policy solutions toward communicating the severity and risks associated with natural disasters.

  16. 2015 wind energy observatory. Analysis of market, jobs and future of the wind energy sector in France

    International Nuclear Information System (INIS)

    Perot, Olivier; Autier, Emmanuel

    2015-11-01

    This Power Point presentation proposes graphs, figures, tables and comments on the status and evolution of jobs in the wind energy sector (a growing sector, analysis of job locations), of the wind energy market (assessment of a growing market, dynamic French regions, competitive context, evolution of technologies with higher machines, larger wind farms and a growing production), and on the future of wind energy (a growing number of training courses, an active R and D all over the country, a structuring sector). Sheets presenting actors per categories, and maps of regional activity location are provided in appendix

  17. Investigation of the interactions between wind turbines and radio systems aimed at establishing co-siting guidelines. Phase 1: Introduction and modelling of wind turbine scatter, appendices E, F and G

    International Nuclear Information System (INIS)

    Dabis, H.S.; Chignell, R.J.

    1997-01-01

    The potential for wind turbines to interfere with radio systems can be a source of conflict between radio operators and the wind energy community. In this report, the problem of accurately predicting the effects of wind turbines on radio systems with the aim of establishing guidelines for their installation is investigated. Initially models for the scatter mechanisms that occur at the wind turbine are developed. These models predict the wind turbine radar cross section and the modulation effects due to the rotation of the blades. Initial validation of these models is established by comparing the predicted results with a set of measurements obtained from experiments performed on a 20:1 scale model wind turbine. It is shown that generally these results agree well. These results are then used in the guideline formulation to compute, for specific radio systems, regions where wind turbines cannot be installed. Examples using realistic parameters for various radio systems are presented. Further validation of the derived models is required. (author)

  18. The immunology of the vermiform appendix: a review of the literature.

    Science.gov (United States)

    Kooij, I A; Sahami, S; Meijer, S L; Buskens, C J; Te Velde, A A

    2016-10-01

    This literature review assesses the current knowledge about the immunological aspects of the vermiform appendix in health and disease. An essential part of its immunological function is the interaction with the intestinal bacteria, a trait shown to be preserved during its evolution. The existence of the appendiceal biofilm in particular has proved to have a beneficial effect for the entire gut. In assessing the influence of acute appendicitis and the importance of a normally functioning gut flora, however, multiple immunological aspects point towards the appendix as a priming site for ulcerative colitis. Describing the immunological and microbiotical changes in the appendix during acute and chronic inflammation of the appendix, this review suggests that this association becomes increasingly plausible. Sustained by the distinct composition of cells, molecules and microbiota, as well as by the ever more likely negative correlation between the appendix and ulcerative colitis, the idea of the appendix being a vestigial organ should therefore be discarded. © 2016 British Society for Immunology.

  19. Implications of the Detection of X-rays From Pluto by Chandra for Its Solar Wind - Neutral Atmosphere Interaction

    Science.gov (United States)

    Lisse, C. M.

    2016-12-01

    Using the Chandra X-Ray Observatory, we have obtained low-resolution imaging X-ray spectrophotometry of the Pluto system in support of the New Horizons (NH) flyby. In a total of 174 ksec of on-target time, we measured 8 photons from 0.31 to 0.60 keV in a co-moving 11 x 11 pixel2 box (the 90% flux aperture for fixed background sources in the field) measuring 121,000 x 121,000 km2 (or 100 x 100 RPluto) at Pluto. The Pluto photons do not have the spectral shape of the background, are coincident with a 90% flux aperture co-moving with Pluto, and are not confused with any background source, so we consider them as sourced from the Pluto system. Allowing for background, we find a net signal of 6.8 counts and a statistical noise level of 1.2 counts, for a detection of Pluto at > 99.95%. The mean 0.31 - 0.60 keV X-ray power from Pluto is 200 +200/-100 MW, in the middle range of X-ray power levels seen for other known solar system emission sources: auroral precipitation, solar X-ray scattering, and charge exchange (CXE) between solar wind (SW) ions and atmospheric neutrals. We eliminate auroral effects as a source, as Pluto has no known magnetic field and the NH/Alice UV spectrometer detected no airglow from Pluto during the flyby. Atmospheric haze particles could produce resonant scattering of solar X-rays from Pluto, but the energy signature of the detected photons does not match the solar spectrum and estimates of Pluto's scattered X-ray emission are 2 to 3 orders of magnitude lower than seen in our observations. CXE-driven emission from hydrogenic and heliogenic SW carbon, nitrogen, and oxygen ions can produce the energy signature seen, and the 6 x 1025 neutral gas escape rate from Pluto deduced from NH data (Gladstone et al. 2016) can support the 3.0 +3.0/-1.5 x 1024 X-ray photons/s emission rate required by our observations. Using the SW proton density and speed measured by the NH/SWAP instrument in the vicinity of Pluto at the time of the photon emissions, we find a

  20. Wind Turbine Optimization with WISDEM

    Energy Technology Data Exchange (ETDEWEB)

    Dykes, Katherine L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Damiani, Rick R [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Graf, Peter A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Scott, George N [National Renewable Energy Laboratory (NREL), Golden, CO (United States); King, Ryan N [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Guo, Yi [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Quick, Julian [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sethuraman, Latha [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Veers, Paul S [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Ning, Andrew [Brigham Young University

    2018-01-03

    This presentation for the Fourth Wind Energy Systems Engineering Workshop explains the NREL wind energy systems engineering initiative-developed analysis platform and research capability to capture important system interactions to achieve a better understanding of how to improve system-level performance and achieve system-level cost reductions. Topics include Wind-Plant Integrated System Design and Engineering Model (WISDEM) and multidisciplinary design analysis and optimization.

  1. Wind energy. Market prospects to 2006

    International Nuclear Information System (INIS)

    Huckle, R.

    2002-01-01

    is given to illustrate the activities of developers, owners, operators and equipment manufacturers. Chapter 6 is a directory of selected companies in the wind energy industry. Contact details are given for international developers, operators and equipment manufacturers. Chapter 7 is an appendix giving details of major associations and organizations connected with wind energy. There is also an Internet directory

  2. Reminiscences on the study of wind waves.

    Science.gov (United States)

    Mitsuyasu, Hisashi

    2015-01-01

    The wind blowing over sea surface generates tiny wind waves. They develop with time and space absorbing wind energy, and become huge wind waves usually referred to ocean surface waves. The wind waves cause not only serious sea disasters but also take important roles in the local and global climate changes by affecting the fluxes of momentum, heat and gases (e.g. CO2) through the air-sea boundary. The present paper reviews the selected studies on wind waves conducted by our group in the Research Institute for Applied Mechanics (RIAM), Kyushu University. The themes discussed are interactions between water waves and winds, the energy spectrum of wind waves, nonlinear properties of wind waves, and the effects of surfactant on some air-sea interaction phenomena.

  3. Wind noise under a pine tree canopy.

    Science.gov (United States)

    Raspet, Richard; Webster, Jeremy

    2015-02-01

    It is well known that infrasonic wind noise levels are lower for arrays placed in forests and under vegetation than for those in open areas. In this research, the wind noise levels, turbulence spectra, and wind velocity profiles are measured in a pine forest. A prediction of the wind noise spectra from the measured meteorological parameters is developed based on recent research on wind noise above a flat plane. The resulting wind noise spectrum is the sum of the low frequency wind noise generated by the turbulence-shear interaction near and above the tops of the trees and higher frequency wind noise generated by the turbulence-turbulence interaction near the ground within the tree layer. The convection velocity of the low frequency wind noise corresponds to the wind speed above the trees while the measurements showed that the wind noise generated by the turbulence-turbulence interaction is near stationary and is generated by the slow moving turbulence adjacent to the ground. Comparison of the predicted wind noise spectrum with the measured wind noise spectrum shows good agreement for four measurement sets. The prediction can be applied to meteorological estimates to predict the wind noise under other pine forests.

  4. Continuous supersonic plasma wind tunnel

    DEFF Research Database (Denmark)

    Andersen, S.A.; Jensen, Vagn Orla; Nielsen, P.

    1969-01-01

    The normal magnetic field configuration of a Q device has been modified to obtain a 'magnetic Laval nozzle'. Continuous supersonic plasma 'winds' are obtained with Mach numbers ~3. The magnetic nozzle appears well suited for the study of the interaction of supersonic plasma 'winds' with either...

  5. Stereo Photogrammetry Measurements of the Position and Attitude of a Nozzle-Plume/Shock-Wave Interaction Model in the NASA Ames 9- by 7-Ft Supersonic Wind Tunnel

    Science.gov (United States)

    Schairer, Edward T.; Kushner, Laura K.; Drain, Bethany A.; Heineck, James T.; Durston, Donald A.

    2017-01-01

    Stereo photogrammetry was used to measure the position and attitude of a slender body of revolution during nozzle-plume/shock-wave interaction tests in the NASA Ames 9- by 7-Ft Supersonic Wind Tunnel. The model support system was designed to allow the model to be placed at many locations in the test section relative to a pressure rail on one sidewall. It included a streamwise traverse as well as a thin blade that offset the model axis from the sting axis. With these features the support system was more flexible than usual resulting in higher-than-usual uncertainty in the position and attitude of the model. Also contributing to this uncertainty were the absence of a balance, so corrections for sting deflections could not be applied, and the wings-vertical orientation of the model, which precluded using a gravity-based accelerometer to measure pitch angle. Therefore, stereo photogrammetry was chosen to provide independent measures of the model position and orientation. This paper describes the photogrammetry system and presents selected results from the test.

  6. Wind Tunnel Investigation of Passive Vortex Control and Vortex-Tail Interactions on a Slender Wing at Subsonic and Transonic Speeds

    Science.gov (United States)

    Erickson, Gary E.

    2013-01-01

    A wind tunnel experiment was conducted in the NASA Langley 8-Foot Transonic Pressure Tunnel to determine the effects of passive porosity on vortex flow interactions about a slender wing configuration at subsonic and transonic speeds. Flow-through porosity was applied in several arrangements to a leading-edge extension, or LEX, mounted to a 65-degree cropped delta wing as a longitudinal instability mitigation technique. Test data were obtained with LEX on and off in the presence of a centerline vertical tail and twin, wing-mounted vertical fins to quantify the sensitivity of the aerodynamics to tail placement and orientation. A close-coupled canard was tested as an alternative to the LEX as a passive flow control device. Wing upper surface static pressure distributions and six-component forces and moments were obtained at Mach numbers of 0.50, 0.85, and 1.20, unit Reynolds number of 2.5 million, angles of attack up to approximately 30 degrees, and angles of sideslip to +/-8 degrees. The off-surface flow field was visualized in cross planes on selected configurations using a laser vapor screen flow visualization technique. Tunnel-to-tunnel data comparisons and a Reynolds number sensitivity assessment were also performed. 15.

  7. Sequential Convex Programming for Power Set-point Optimization in a Wind Farm using Black-box Models, Simple Turbine Interactions, and Integer Variables

    DEFF Research Database (Denmark)

    Hovgaard, Tobias Gybel; Larsen, Lars F. S.; Jørgensen, John Bagterp

    2012-01-01

    We consider the optimization of power set-points to a large number of wind turbines arranged within close vicinity of each other in a wind farm. The goal is to maximize the total electric power extracted from the wind, taking the wake effects that couple the individual turbines in the farm...... describing the turbulent wind fields’ propagation through the farm are included in a highly detailed black-box model, numerical results for any given values of the parameter sets can easily be evaluated. However, analytic expressions for model representation in the optimization algorithms might be hard...... convex approximation and compare with mixed-integer optimization tools. We demonstrate the method on a verified model and for various sizes and configurations of the wind farm. For all tested scenarios we observe a distribution of the power set-points which is at least as good as, and in many cases...

  8. 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.

  9. An integrated modeling method for wind turbines

    Science.gov (United States)

    Fadaeinedjad, Roohollah

    To study the interaction of the electrical, mechanical, and aerodynamic aspects of a wind turbine, a detailed model that considers all these aspects must be used. A drawback of many studies in the area of wind turbine simulation is that either a very simple mechanical model is used with a detailed electrical model, or vice versa. Hence the interactions between electrical and mechanical aspects of wind turbine operation are not accurately taken into account. In this research, it will be shown that a combination of different simulation packages, namely TurbSim, FAST, and Simulink can be used to model the aerodynamic, mechanical, and electrical aspects of a wind turbine in detail. In this thesis, after a review of some wind turbine concepts and software tools, a simulation structure is proposed for studying wind turbines that integrates the mechanical and electrical components of a wind energy conversion device. Based on the simulation structure, a comprehensive model for a three-bladed variable speed wind turbine with doubly-fed induction generator is developed. Using the model, the impact of a voltage sag on the wind turbine tower vibration is investigated under various operating conditions such as power system short circuit level, mechanical parameters, and wind turbine operating conditions. It is shown how an electrical disturbance can cause more sustainable tower vibrations under high speed and turbulent wind conditions, which may disrupt the operation of pitch control system. A similar simulation structure is used to model a two-bladed fixed speed wind turbine with an induction generator. An extension of the concept is introduced by adding a diesel generator system. The model is utilized to study the impact of the aeroelastic aspects of wind turbine (i.e. tower shadow, wind shears, yaw error, turbulence, and mechanical vibrations) on the power quality of a stand-alone wind-diesel system. Furthermore, an IEEE standard flickermeter model is implemented in a

  10. Current observations from a looking down vertical V-ADCP: interaction with winds and tide? The case of Giglio Island (Tyrrhenian Sea, Italy

    Directory of Open Access Journals (Sweden)

    Laura Cutroneo

    2017-04-01

    Full Text Available In the context of the environmental monitoring of the Concordia wreck removal project, measurements of currents, winds and sea level height were made along the eastern coast of the Giglio Island, Tyrrhenian Sea (Italy, during 2012–2013. The aim of the study was to investigate the effect of atmospheric forcing and periodic sea-level changes on the coastal currents. Normalised Cross-Correlation Function analysis allowed us to correlate these observations. A marked inter-seasonal variability was found in both current and local wind velocity observations but a significant level of correlation between the data was only found during strong wind events. Current and wind directions appeared to be uncorrelated and current measurements showed a predominant NW–SE direction, presumably linked to the shape and orientation of Giglio Island itself. During strong winds from the SSE, current flow was towards the NNW but it suddenly switched from the NNW to the SE at the end of wind events. The results show that, at Giglio Island, currents are principally dominated by the general cyclonic Tyrrhenian circulation, and, secondly, by strong wind events. The sea level had no effects on the current regime.

  11. Astrospheres and Solar-like Stellar Winds

    Directory of Open Access Journals (Sweden)

    Wood Brian E.

    2004-07-01

    Full Text Available Stellar analogs for the solar wind have proven to be frustratingly difficult to detect directly. However, these stellar winds can be studied indirectly by observing the interaction regions carved out by the collisions between these winds and the interstellar medium (ISM. These interaction regions are called "astrospheres", analogous to the "heliosphere" surrounding the Sun. The heliosphere and astrospheres contain a population of hydrogen heated by charge exchange processes that can produce enough H I Ly alpha absorption to be detectable in UV spectra of nearby stars from the Hubble Space Telescope (HST. The amount of astrospheric absorption is a diagnostic for the strength of the stellar wind, so these observations have provided the first measurements of solar-like stellar winds. Results from these stellar wind studies and their implications for our understanding of the solar wind are reviewed here. Of particular interest are results concerning the past history of the solar wind and its impact on planetary atmospheres.

  12. Aeroservoelasticity of wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Skovmose Kallesoee, B.

    2007-12-14

    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 address. The main contribution of this thesis is the development of an aeroelastic blade model which on the one hand includes the important effects of steady state blade deformation, gravity and pitch action, and on the other it is transparent, suitable for analytical analysis and parameter studies, 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 terms in these equations are discussed and given physical interpretations; 2) Steady state blade deformation and induced velocities are computed by combining the PDEs with a steady state aerodynamic model; 3) Aeroelastic modes of motion are computed by combining the linearized PDEs with a linear unsteady aerodynamic model; this model is used to analyze how blade deformation effects the modes of motion; and 4) the linear aeroelastic blade model is derived by a modal expansion of the linearized PDEs combined with a linear unsteady aerodynamic model. The aeroelastic blade model has many similarities 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 is used to develop a state estimator for estimating the wind speed and wind shear, and to suggest a load reducing controller. The state estimator estimates the wind shear very

  13. 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...

  14. 14 CFR Appendix B to Part 420 - Method for Defining a Flight Corridor

    Science.gov (United States)

    2010-01-01

    ... perform the launch area analysis of this appendix. The data requirements are identified in table B-1 along... Data Requirements Data category Data item Data source Meteorological Data Local statistical wind data... (%) These data may be obtained from:Global Gridded Upper Air Statistics, Climate Applications Branch...

  15. Wind energy

    CERN Document Server

    Woll, Kris

    2016-01-01

    Across the country, huge open spaces are covered in gently turning wind turbines. In Wind Energy, explore how these machines generate electricity, learn about the history of wind power, and discover the latest advances in the field. Easy-to-read text, vivid images, and helpful back matter give readers a clear look at this subject. Features include a table of contents, infographics, a glossary, additional resources, and an index. Aligned to Common Core Standards and correlated to state standards. Core Library is an imprint of Abdo Publishing, a division of ABDO.

  16. Interaction of Atmospheric Turbulence with Blade Boundary Layer Dynamics on a 5MW Wind Turbine using Blade-Boundary-Layer-Resolved CFD with hybrid URANS-LES.

    Energy Technology Data Exchange (ETDEWEB)

    Vijayakumar, Ganesh [National Renewable Energy Lab. (NREL), Golden, CO (United States); Pennsylvania State Univ., University Park, PA (United States); Brasseur, James [Pennsylvania State Univ., University Park, PA (United States); Univ. of Colorado, Boulder, CO (United States); Lavely, Adam; Jayaraman, Balaji; Craven, Brent

    2016-01-04

    We describe the response of the NREL 5 MW wind turbine blade boundary layer to the passage of atmospheric turbulence using blade-boundary-layer-resolved computational fluid dynamics with hybrid URANS-LES modeling.

  17. Laser Atmospheric Wind Sounder (LAWS) phase 1. Volume 2

    Science.gov (United States)

    1990-04-01

    This report summarizes and documents the results of the 12-month phase 1 work effort. The objective of phase 1 was to establish the conceptional definition of the laser atmospheric wind sounder (LAWS) sensor system, including accommodations analyses to ensure compatibility with the Space Station Freedom (SSF) and the Earth Observing System (EOS) Polar Orbiting Platform (POP). Various concepts were investigated with trade studies performed to select the configuration to be carried forward to the phase 2 Preliminary Design Definition. A summary of the LAWS system and subsystem trade studies that were performed leading to the baseline design configuration is presented in the appendix. The overall objective of the LAWS Project is to define, design, and implement an operational space based facility, LAWS, for accurate measurement of Earth wind profiles. Phase 1 addressed three major areas: (1) requirements definition; (2) instrument concepts and configurations; and (3) performance analysis. For the LAWS instrument concepts and configurations, the issues which press the technological state of the art are reliable detector lifetime and laser performance and lifetime. Lag angle compensation, pointing accuracy, satellite navigation, and telescope design are significant technical issues, but they are considered to be currently state of the art. The primary issues for performance analysis concern interaction with the atmosphere in terms of backscatter and attenuation, wind variance, and cloud blockage. The phase 1 tasks were formulated to address these significant technical issues and demonstrate the technical feasibility of the LAWS concept. Primary emphasis was placed on analysis/trade and identification of candidate concepts. Promising configurations were evaluated for performance, sensitivities, risks, and budgetary costs. Lockheed's baseline LAWS configuration is presented.

  18. World Wind

    Data.gov (United States)

    National Aeronautics and Space Administration — World Wind allows any user to zoom from satellite altitude into any place on Earth, leveraging high resolution LandSat imagery and SRTM elevation data to experience...

  19. Appendix C: GLEES Macroinvertebrates

    Science.gov (United States)

    B. C. Kondratieff

    1994-01-01

    This Appendix identifies macroinvertebrate species found in streams and lakes at GLEES during a preliminary qualitative survey conducted in the summer of 1988 by Dr. Boris Kondratieff. The littoral zones of each lake and each stream were sampled by hand-picking and with a triangle net. Insect voucher specimens are maintained in the Gillette Entomological Museum at...

  20. 78 FR 29364 - Exelon Corporation, Exelon Wind 1, LLC, Exelon Wind 2, LLC, Exelon Wind 3, LLC, Exelon Wind 4...

    Science.gov (United States)

    2013-05-20

    ...-005, QF07-257-004] Exelon Corporation, Exelon Wind 1, LLC, Exelon Wind 2, LLC, Exelon Wind 3, LLC, Exelon Wind 4, LLC, Exelon Wind 5, LLC, Exelon Wind 6, LLC, Exelon Wind 7, LLC, Exelon Wind 8, LLC, Exelon Wind 9, LLC, Exelon Wind 10, LLC, Exelon Wind 11, LLC, High Plains Wind Power, LLC v. Xcel Energy...

  1. 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.

  2. Review report 2004. The Danish offshore wind farm demonstration project: Horns Rev and Nysted offshore wind farms. Environmental impact assessment and monitoring

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-10-15

    The present review report presents the two wind farms Horns Rev and Nysted with regard to environmental characteristics and the results of the environmental studies carried out in connection with the Environmental Impact Assessment (EIA) and the baseline and monitoring programmes at the two sites. The descriptions of the programmes are based on extracts from the individual annual reports. Detailed information on method, programmes and conclusions can be found in these reports (see Appendix 1). This review report is divided into two parts. The first part contains a description of the potential environmental impacts of offshore wind farms and the potentially affected part of the environment. The second part includes a description of Horns Rev and Nysted Offshore Wind Farm and the environmental studies carried out here until the end of 2003. Appendix I is a list of the literature published on the studies carried out at Horns Rev and Nysted Offshore Wind Farm. Appendix II is a list of some of the literature relevant to the demonstration projects but not directly related to the projects. The offshore wind farm situated in the Roedsand area is officially denoted Nysted Offshore Wind Farm, and in the present report the denotation 'Nysted' will be used as well when referring to Nysted Offshore Wind Farm. The denotation Roedsand will be used when referring to the actual area Roedsand. (au)

  3. Characteristics of PMSE associated with the geomagnetic disturbance driven by corotating interaction region and high-speed solar wind streams in the declining solar cycle 23

    Science.gov (United States)

    Lee, Young-Sook; Kirkwood, Sheila; Kwak, Young-Sil; Shepherd, Gordon G.; Kim, Kyung-Chan; Yang, Tae-Yong; Kero, Antti

    2015-04-01

    We report interannual variations of the correlation between the reflectivity of polar mesospheric summer echoes (PMSEs) and solar wind parameters (speed and dynamic pressure), and AE index as a proxy of geomagnetic disturbances, and cosmic noise absorption (CNA) in the declining phase (2001-2008) of solar cycle 23. PMSEs are observed by 52 MHz VHF radar measurements at Esrange (67.8°N, 20.4°E), Sweden. In approaching the solar minimum years, high-speed solar wind streams emanate from frequently emerging coronal holes, leading to 7, 9, and 13.5 day periodicities in their arrival at Earth. Periodicities of 7 and/or 9 days are found in PMSE reflectivity in 2005-2006 and 2008. Periodicity-resolved correlations at 7 and 9 days of both D region ionization observed by cosmic noise absorption (CNA) and PMSE with solar wind speed and AE index vary from year to year but generally increase as solar minimum is approached. PMSEs have a higher periodicity-resolved correlation with AE index than the solar wind speed. In addition, cross correlation of PMSE reflectivity with AE index is mostly higher than with CNA in solar minimum years (2005-2008). This can signify that high-speed solar wind stream-induced high-energy particles possibly have strong influence on CNA, but not as much as on PMSE, especially for the years of significant periodicities occurring.

  4. Wind power integration connection and system operational aspects

    CERN Document Server

    Fox, Brendan

    2014-01-01

    Wind Power Integration provides a wide-ranging discussion on all major aspects of wind power integration into electricity supply systems. This second edition has been fully revised and updated to take account of the significant growth in wind power deployment in the past few years. New discussions have been added to describe developments in wind turbine generator technology and control, the network integration of wind power, innovative ways to integrate wind power when its generation potential exceeds 50% of demand, case studies on how forecasting errors have affected system operation, and an update on how the wind energy sector has fared in the marketplace. Topics covered include: the development of wind power technology and its world-wide deployment; wind power technology and the interaction of various wind turbine generator types with the utility network; and wind power forecasting and the challenges faced by wind energy in modern electricity markets.

  5. The vermiform appendix: a review.

    Science.gov (United States)

    Barlow, Andrew; Muhleman, Mitchel; Gielecki, Jerzy; Matusz, Petru; Tubbs, R Shane; Loukas, Marios

    2013-10-01

    New research on the vermiform appendix has shed light on its function. In further understanding the function of the appendix, this information should not negatively impact the clinical judgment in the event of appendicitis. Although the appendix and its pathology have been noted for centuries, it still presents a challenge in the operating room. The most common emergency surgical procedure performed is an appendectomy. Its highly variable position within the abdomen can cause confusion for clinicians. However, improved imaging modalities have heightened the physician's ability to diagnose disease of this organ. This article reviews germane literature regarding the human vermiform appendix. Copyright © 2013 Wiley Periodicals, Inc.

  6. Interaction of the plasma tail of comet Bradfield 1979L on 1980 February 6 with a possibly flare-generated solar-wind disturbance

    International Nuclear Information System (INIS)

    Niedner, M.B. Jr.; Brandt, J.C.; Zwickl, R.D.; Bame, S.J.

    1982-01-01

    Solar-wind plasma data from the ISEE-3 and Helios 2 spacecraft have been examined in order to explain a uniquely rapid 10 0 turning of the plasma tail of comet Bradfield 1979L on 1980 February 6. An earlier study conducted before the availability of in situ solar-wind data (Brandt et al., 1980) suggested that the tail position angle change occurred in response to a solar-wind velocity shear across which the polar component changed by approx. 50 km s - 1 . The present contribution confirms this result and further suggests that the comet-tail activity was caused by non-corotating, disturbed plasma flows probably associated with an Importance 1B solar flare

  7. Optimization of wind turbine rotors

    Energy Technology Data Exchange (ETDEWEB)

    Holmkvist, Jonas

    1998-05-01

    A computer program for aerodynamic optimization of wind turbine rotors has been written in Fortran with the purpose to maximize the annual energy production. The constraints is the maximum power output from the turbine and maximum and minimum values on the design variables. The design of the rotor is described by the chord- and twist distribution. The chord- and twist distributions are described with Bezier splines which, with a few number of control points, are very flexible. The Bezier control points are the design variables which are optimized by the optimization program. The optimization method used in the program is the Method of Moving Asymptotes, MMA, suggested by Krister Svanberg at the Royal Institute of Technology in Stockholm. MMA is a stable method and it seems suitable for this application. It is also in general easy to implement constraints. It seems like there are many local maximum points and the variations in the annual energy production between the total maximum points are very small, so there are many solutions to choose between and finding the global maximum point can be a problem. The problem could possibly be avoided with smaller wind steps near the rated wind. In future versions of the optimization program the Reynolds number dependents of the aerodynamic coefficients should be taken into consideration. Constraints for the thrust and the aerodynamic noise should also be implemented in the program 8 refs, 8 figs, 13 tabs, 14 appendixes

  8. Establishing a Comprehensive Wind Energy Program

    Energy Technology Data Exchange (ETDEWEB)

    Fleeter, Sanford [Purdue University

    2012-09-30

    This project was directed at establishing a comprehensive wind energy program in Indiana, including both educational and research components. A graduate/undergraduate course ME-514 - Fundamentals of Wind Energy has been established and offered and an interactive prediction of VAWT performance developed. Vertical axis wind turbines for education and research have been acquired, instrumented and installed on the roof top of a building on the Calumet campus and at West Lafayette (Kepner Lab). Computational Fluid Dynamics (CFD) calculations have been performed to simulate these urban wind environments. Also, modal dynamic testing of the West Lafayette VAWT has been performed and a novel horizontal axis design initiated. The 50-meter meteorological tower data obtained at the Purdue Beck Agricultural Research Center have been analyzed and the Purdue Reconfigurable Micro Wind Farm established and simulations directed at the investigation of wind farm configurations initiated. The virtual wind turbine and wind turbine farm simulation in the Visualization Lab has been initiated.

  9. WIND TURBINES FOR WIND POWER INSTALLATIONS

    Directory of Open Access Journals (Sweden)

    Barladean A.S.

    2008-04-01

    Full Text Available The problem of wind turbine choice for wind power stations is examined in this paper. It is shown by comparison of parameters and characteristics of wind turbines, that for existing modes and speeds of wind in territory of Republic of Moldova it is necessary to use multi-blade small speed rotation wind turbines of fan class.

  10. 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.

  11. Greenhouse gas and air pollutant emission reduction potentials of renewable energy--case studies on photovoltaic and wind power introduction considering interactions among technologies in Taiwan.

    Science.gov (United States)

    Kuo, Yu-Ming; Fukushima, Yasuhiro

    2009-03-01

    To achieve higher energy security and lower emission of greenhouse gases (GHGs) and pollutants, the development of renewable energy has attracted much attention in Taiwan. In addition to its contribution to the enhancement of reliable indigenous resources, the introduction of renewable energy such as photovoltaic (PV) and wind power systems reduces the emission of GHGs and air pollutants by substituting a part of the carbon- and pollutant-intensive power with power generated by methods that are cleaner and less carbon-intensive. To evaluate the reduction potentials, consequential changes in the operation of different types of existing power plants have to be taken into account. In this study, a linear mathematical programming model is constructed to simulate a power mix for a given power demand in a power market sharing a cost-minimization objective. By applying the model, the emission reduction potentials of capacity extension case studies, including the enhancement of PV and wind power introduction at different scales, were assessed. In particular, the consequences of power mix changes in carbon dioxide, nitrogen oxides, sulfur oxides, and particulates were discussed. Seasonally varying power demand levels, solar irradiation, and wind strength were taken into account. In this study, we have found that the synergetic reduction of carbon dioxide emission induced by PV and wind power introduction occurs under a certain level of additional installed capacity. Investigation of a greater variety of case studies on scenario development with emerging power sources becomes possible by applying the model developed in this study.

  12. Interactive effects of moss-dominated crusts and Artemisia ordosica on wind erosion and soil moisture in Mu Us sandland, China.

    Science.gov (United States)

    Yang, Yongsheng; Bu, Chongfeng; Mu, Xingmin; Shao, Hongbo; Zhang, Kankan

    2014-01-01

    To better understand the effects of biological soil crusts (BSCs) on soil moisture and wind erosion and study the necessity and feasibility of disturbance of BSCs in the Mu Us sandland, the effects of four treatments, including moss-dominated crusts alone, Artemisia ordosica alone, bare sand, and Artemisia ordosica combined with moss-dominated crusts, on rainwater infiltration, soil moisture, and annual wind erosion were observed. The major results are as follows. (1) The development of moss-dominated crusts exacerbated soil moisture consumption and had negative effects on soil moisture in the Mu Us sandland. (2) Moss-dominated crusts significantly increased soil resistance to wind erosion, and when combined with Artemisia ordosica, this effect became more significant. The contribution of moss-dominated crusts under Artemisia ordosica was significantly lower than that of moss-dominated crusts alone in sites where vegetative coverage > 50%. (3) Finally, an appropriate disturbance of moss-dominated crusts in the rainy season in sites with high vegetative coverage improved soil water environment and vegetation succession, but disturbance in sites with little or no vegetative cover should be prohibited to avoid the exacerbation of wind erosion.

  13. Interactive Effects of Moss-Dominated Crusts and Artemisia ordosica on Wind Erosion and Soil Moisture in Mu Us Sandland, China

    Science.gov (United States)

    Yang, Yongsheng; Bu, Chongfeng; Mu, Xingmin; Shao, Hongbo; Zhang, Kankan

    2014-01-01

    To better understand the effects of biological soil crusts (BSCs) on soil moisture and wind erosion and study the necessity and feasibility of disturbance of BSCs in the Mu Us sandland, the effects of four treatments, including moss-dominated crusts alone, Artemisia ordosica alone, bare sand, and Artemisia ordosica combined with moss-dominated crusts, on rainwater infiltration, soil moisture, and annual wind erosion were observed. The major results are as follows. (1) The development of moss-dominated crusts exacerbated soil moisture consumption and had negative effects on soil moisture in the Mu Us sandland. (2) Moss-dominated crusts significantly increased soil resistance to wind erosion, and when combined with Artemisia ordosica, this effect became more significant. The contribution of moss-dominated crusts under Artemisia ordosica was significantly lower than that of moss-dominated crusts alone in sites where vegetative coverage > 50%. (3) Finally, an appropriate disturbance of moss-dominated crusts in the rainy season in sites with high vegetative coverage improved soil water environment and vegetation succession, but disturbance in sites with little or no vegetative cover should be prohibited to avoid the exacerbation of wind erosion. PMID:24982973

  14. Seabird-wind farm interactions during the breeding season vary within and between years: A case study of lesser black-backed gull Larus fuscus in the UK

    NARCIS (Netherlands)

    Thaxter, C.B.; Ross-Smith, V.H.; Bouten, W.; Clark, N.A.; Conway, G.J.; Rejfish, M.M.; Burton, N.H.K.

    2015-01-01

    The marine environment is increasingly pressured from human activities, such as offshore renewable energy developments. Offshore wind farms may pose direct risks to seabirds at protected breeding sites. However, changes in food availability may influence foraging behaviour and habitat use during the

  15. Interactive Effects of Moss-Dominated Crusts and Artemisia ordosica on Wind Erosion and Soil Moisture in Mu Us Sandland, China

    Directory of Open Access Journals (Sweden)

    Yongsheng Yang

    2014-01-01

    Full Text Available To better understand the effects of biological soil crusts (BSCs on soil moisture and wind erosion and study the necessity and feasibility of disturbance of BSCs in the Mu Us sandland, the effects of four treatments, including moss-dominated crusts alone, Artemisia ordosica alone, bare sand, and Artemisia ordosica combined with moss-dominated crusts, on rainwater infiltration, soil moisture, and annual wind erosion were observed. The major results are as follows. (1 The development of moss-dominated crusts exacerbated soil moisture consumption and had negative effects on soil moisture in the Mu Us sandland. (2 Moss-dominated crusts significantly increased soil resistance to wind erosion, and when combined with Artemisia ordosica, this effect became more significant. The contribution of moss-dominated crusts under Artemisia ordosica was significantly lower than that of moss-dominated crusts alone in sites where vegetative coverage > 50%. (3 Finally, an appropriate disturbance of moss-dominated crusts in the rainy season in sites with high vegetative coverage improved soil water environment and vegetation succession, but disturbance in sites with little or no vegetative cover should be prohibited to avoid the exacerbation of wind erosion.

  16. INTERACT

    DEFF Research Database (Denmark)

    Jochum, Elizabeth; Borggreen, Gunhild; Murphey, TD

    This paper considers the impact of visual art and performance on robotics and human-computer interaction and outlines a research project that combines puppetry and live performance with robotics. Kinesics—communication through movement—is the foundation of many theatre and performance traditions...... including puppetry and dance. However, the aesthetics of these traditions vary across cultures and carry different associative and interpretive meanings. Puppetry offers a useful frame for understanding the relationship between abstract and imitative gestures and behavior, and instantiates the complex...... interaction between a human operator and an artificial actor or agent. We can apply insights from puppetry to develop culturally-aware robots. Here we describe the development of a robotic marionette theatre wherein robotic controllers assume the role of human puppeteers. The system has been built, tested...

  17. Interactions

    DEFF Research Database (Denmark)

    The main theme of this anthology is the unique interaction between mathematics, physics and philosophy during the beginning of the 20th century. Seminal theories of modern physics and new fundamental mathematical structures were discovered or formed in this period. Significant physicists such as ......The main theme of this anthology is the unique interaction between mathematics, physics and philosophy during the beginning of the 20th century. Seminal theories of modern physics and new fundamental mathematical structures were discovered or formed in this period. Significant physicists...... such as Lorentz and Einstein as well as mathematicians such as Poincare, Minkowski, Hilbert and Weyl contributed to this development. They created the new physical theories and the mathematical disciplines that play such paramount roles in their mathematical formulations. These physicists and mathematicians were...... also key figures in the philosophical discussions of nature and science - from philosophical tendencies like logical empiricism via critical rationalism to various neo-Kantian trends....

  18. Wind power

    International Nuclear Information System (INIS)

    2006-06-01

    This road-map proposes by the Group Total aims to inform the public on the wind power. It presents the principles, the technology takes off, its applications and technology focus, the global market trends and the outlooks and Total commitments in the domain. (A.L.B.)

  19. Wind Energy Japan

    Energy Technology Data Exchange (ETDEWEB)

    Komatsubara, Kazuyo [Embassy of the Kingdom of the Netherlands, Tokyo (Japan)

    2012-06-15

    An overview is given of wind energy in Japan: Background; Wind Energy in Japan; Japanese Wind Energy Industry; Government Supports; Useful Links; Major Japanese Companies; Profiles of Major Japanese Companies; Major Wind Energy Projects in Japan.

  20. 3-D Hybrid Kinetic Modeling of the Interaction Between the Solar Wind and Lunar-like Exospheric Pickup Ions in Case of Oblique/ Quasi-Parallel/Parallel Upstream Magnetic Field

    Science.gov (United States)

    Lipatov, A. S.; Farrell, W. M.; Cooper, J. F.; Sittler, E. C., Jr.; Hartle, R. E.

    2015-01-01

    The interactions between the solar wind and Moon-sized objects are determined by a set of the solar wind parameters and plasma environment of the space objects. The orientation of upstream magnetic field is one of the key factors which determines the formation and structure of bow shock wave/Mach cone or Alfven wing near the obstacle. The study of effects of the direction of the upstream magnetic field on lunar-like plasma environment is the main subject of our investigation in this paper. Photoionization, electron-impact ionization and charge exchange are included in our hybrid model. The computational model includes the self-consistent dynamics of the light (hydrogen (+), helium (+)) and heavy (sodium (+)) pickup ions. The lunar interior is considered as a weakly conducting body. Our previous 2013 lunar work, as reported in this journal, found formation of a triple structure of the Mach cone near the Moon in the case of perpendicular upstream magnetic field. Further advances in modeling now reveal the presence of strong wave activity in the upstream solar wind and plasma wake in the cases of quasiparallel and parallel upstream magnetic fields. However, little wave activity is found for the opposite case with a perpendicular upstream magnetic field. The modeling does not show a formation of the Mach cone in the case of theta(Sub B,U) approximately equal to 0 degrees.

  1. INTERACT

    DEFF Research Database (Denmark)

    Jochum, Elizabeth; Borggreen, Gunhild; Murphey, TD

    This paper considers the impact of visual art and performance on robotics and human-computer interaction and outlines a research project that combines puppetry and live performance with robotics. Kinesics—communication through movement—is the foundation of many theatre and performance traditions...... including puppetry and dance. However, the aesthetics of these traditions vary across cultures and carry different associative and interpretive meanings. Puppetry offers a useful frame for understanding the relationship between abstract and imitative gestures and behavior, and instantiates the complex...

  2. Intercalibration and Cross-Correlation of Ace and Wind Solar Wind Data

    Science.gov (United States)

    2003-01-01

    This report covers activities funded from October 1, 1998 through September 30, 2002. Two yearly status reports have been filed on this grant, and they are included as Appendix 1. The purpose of this grant was to compare ACE and Wind solar wind parameters when the two spacecraft were near to one another and then to use the intercalibrated parameters to carry out scientific investigations. In September, 2001 a request for a one-year, no-cost extension until September 30, 2002 was submitted and approved. The statement of work for that extension included adjustment of ACE densities below wind speeds of 350 km/s, a study of shock normal orientations using travel time delays between the two spacecraft, comparison of density jumps at shocks, and a study of temperature anisotropies and double streaming to see if such features evolved between the spacecraft.

  3. Offshore wind power deployment in Germany; Entwicklung der Offshore-Windenergienutzung in Deutschland

    Energy Technology Data Exchange (ETDEWEB)

    Rehfeldt, Knud [Deutsche Windguard GmbH (Germany); Paschedag, Udo [Bundesministerium fuer Umwelt, Naturschutz und Reaktorsicherheit, Berlin (Germany); Boemer, Jens (eds.)

    2007-01-15

    This bilingual brochure in German and English was published by the Federal Minister of the Environment. It discussses aspects of offshore wind power deployment in Germany. The following subjects are gone into: Expansion targets and expansion scenarios; Economic policy; Implementation of the Federal Government's offshore strategy; Offshore wind turbines of German manufacturers; Licensing of offshore wind farms; Regional planning of the North and Baltic Seas; Integration into the grid; Research in the field of offshore wind power. There is also an appendix of useful links. (orig./AKB)

  4. Wind Loads on Structures

    DEFF Research Database (Denmark)

    Dyrbye, Claes; Hansen, Svend Ole

    Wind loads have to be taken into account when designing civil engineering structures. The wind load on structures can be systematised by means of the wind load chain: wind climate (global), terrain (wind at low height), aerodynamic response (wind load to pressure), mechanical response (wind...... pressure to structural response) and design criteria. Starting with an introduction of the wind load chain, the book moves on to meteorological considerations, atmospheric boundary layer, static wind load, dynamic wind load and scaling laws used in wind-tunnel tests. The dynamic wind load covers vibrations...... induced by wind turbulence, vortex shedding, flutter and galloping. The book gives a comprehensive treatment of wind effects on structures and it will be useful for consulting engineers designing wind-sensitive structures. It will also be valuable for students of civil engineering as textbook...

  5. CFD Simulation of Spread Risks of Infectious Disease due to Interactive Wind and Ventilation Airflows via Window Openings in High-Rise Buildings

    Science.gov (United States)

    Niu, J. L.; Gao, N. P.

    2010-05-01

    One of the concerns is that there may exist multiple infectious disease transmission routes across households in high-rise residential buildings, one of which is the natural ventilative airflow through open windows between flats, caused by buoyancy effects. This study presents the modeling of this cascade effect using computational fluid dynamics (CFD) technique. It is found that the presence of the pollutants generated in the lower floor is generally lower in the immediate upper floor by two orders of magnitude, but the risk of infection calculated by the Wells-Riley equation is only around one order of magnitude lower. It is found that, with single-side open-window conditions, wind blowing perpendicularly to the building may either reinforce or suppress the upward transport, depending on the wind speed. High-speed winds can restrain the convective transfer of heat and mass between flats, functioning like an air curtain. Despite the complexities of the air flow involved, it is clear that this transmission route should be taken into account in infection control.

  6. Stellar winds

    International Nuclear Information System (INIS)

    Weymann, R.J.

    1978-01-01

    It is known that a steady outflow of material at comparable rates of mass loss but vastly different speeds is now known to be ubiquitous phenomenon among both the luminous hot stars and the luminous but cool red giants. The flows are probably massive enough in both cases to give rise to significant effects on stellar evolution and the mass balance between stars and the interstellar medium. The possible mechanisms for these phenomena as well as the methods of observation used are described. In particular, the mass-loss processes in stars other than the sun that also involve a steady flow of matter are considered. The evidence for their existence is described, and then the question of whether the process thought to produce the solar wind is also responsible for producing these stellar winds is explored

  7. Appendix C of the Final Report of the Mid-Atlantic Marine Wildlife Surveys, Modeling, and Data

    Energy Technology Data Exchange (ETDEWEB)

    None

    2013-07-01

    The Wind Program hosted a two-day workshop on July 24-25, 2012 with scientists and regulators engaged in marine ecological survey, modeling, and database efforts pertaining to the waters of the Mid-Atlantic region. This is the third appendix to the report, the compendium of pre-workshop answers.

  8. Appendix A of the Final Report of the Mid-Atlantic Marine Wildlife Surveys, Modeling, and Data

    Energy Technology Data Exchange (ETDEWEB)

    None

    2013-07-01

    The Wind Program hosted a two-day workshop on July 24-25, 2012 with scientists and regulators engaged in marine ecological survey, modeling, and database efforts pertaining to the waters of the Mid-Atlantic region. This is the first appendix to the report, the workshop agenda.

  9. Appendix E of the Final Report of the Mid-Atlantic Marine Wildlife Surveys, Modeling, and Data

    Energy Technology Data Exchange (ETDEWEB)

    None

    2013-07-01

    The Wind Program hosted a two-day workshop on July 24-25, 2012 with scientists and regulators engaged in marine ecological survey, modeling, and database efforts pertaining to the waters of the Mid-Atlantic region. This is the fifth appendix to the report, the bibliography of references.

  10. Aerodynamic interactions from reaction controls for lateral control of the M2-F2 lifting-body entry configuration at transonic and supersonic and supersonic Mach numbers. [wind tunnel tests

    Science.gov (United States)

    Bailey, R. O.; Brownson, J. J.

    1979-01-01

    Tests were conducted in the Ames 6 by 6 foot wind tunnel to determine the interaction of reaction jets for roll control on the M2-F2 lifting-body entry vehicle. Moment interactions are presented for a Mach number range of 0.6 to 1.7, a Reynolds number range of 1.2 x 10 to the 6th power to 1.6 x 10 to the 6th power (based on model reference length), an angle-of-attack range of -9 deg to 20 deg, and an angle-of-sideslip range of -6 deg to 6 deg at an angle of attack of 6 deg. The reaction jets produce roll control with small adverse yawing moment, which can be offset by horizontal thrust component of canted jets.

  11. Wind conditions for wind turbine design

    Energy Technology Data Exchange (ETDEWEB)

    Maribo Pedersen, B.

    1999-04-01

    Delegates from Europe and USA attended the meeting and discussed general aspects of wind conditions for wind turbine design. The subjects and the presented papers covered a very broad range of aspects of wind conditions and related influence on the wind turbine. (EHS)

  12. The Wind Energy programme - SFOE Research Programme 2000 - 2003; Programm Wind. Konzept BFE-Forschungsprogramm 'Wind' 2000 - 2003

    Energy Technology Data Exchange (ETDEWEB)

    Horbaty, R.

    2001-07-01

    This document, issued by the Swiss Federal Office of Energy (SFOE) describes the concept behind the Swiss wind energy programme. The first part of the report discusses the origins and development of the wind energy programme in Switzerland, discussing the importance of wind energy and policy matters associated with its promotion. The experience gained during the previous research programmes is reviewed. The degree to which targets were reached, promotional activities, the central government's own wind energy activities and the results of a programme evaluation are discussed. Lists of projects that have been realised and activities that have been carried out are presented and positive and negative influences on development are noted. A second part is dedicated to the goals of the wind energy programme in terms of target figures for the year 2010 and the strategies chosen to reach these goals, including pilot and demonstration projects (P and D) and promotional activities. Details of the P and D programme including lists of wind-power projects to be supported, the priorities that have been set and information and further education that is to be provided, are given. New activities in the wind power area such as the development of new type of wind turbine especially suited to alpine conditions are discussed. The role of the Swiss Association for Wind Energy 'Suisse Eole' as a network-partner in the wind energy programme is discussed. An appendix provides details of wind energy projects in Switzerland, market partners and customers. The results of a survey made of wind energy activities at Swiss institutes of higher education are presented.

  13. Solar wind classification from a machine learning perspective

    Science.gov (United States)

    Heidrich-Meisner, V.; Wimmer-Schweingruber, R. F.

    2017-12-01

    It is a very well known fact that the ubiquitous solar wind comes in at least two varieties, the slow solar wind and the coronal hole wind. The simplified view of two solar wind types has been frequently challenged. Existing solar wind categorization schemes rely mainly on different combinations of the solar wind proton speed, the O and C charge state ratios, the Alfvén speed, the expected proton temperature and the specific proton entropy. In available solar wind classification schemes, solar wind from stream interaction regimes is often considered either as coronal hole wind or slow solar wind, although their plasma properties are different compared to "pure" coronal hole or slow solar wind. As shown in Neugebauer et al. (2016), even if only two solar wind types are assumed, available solar wind categorization schemes differ considerably for intermediate solar wind speeds. Thus, the decision boundary between the coronal hole and the slow solar wind is so far not well defined.In this situation, a machine learning approach to solar wind classification can provide an additional perspective.We apply a well-known machine learning method, k-means, to the task of solar wind classification in order to answer the following questions: (1) How many solar wind types can reliably be identified in our data set comprised of ten years of solar wind observations from the Advanced Composition Explorer (ACE)? (2) Which combinations of solar wind parameters are particularly useful for solar wind classification?Potential subtypes of slow solar wind are of particular interest because they can provide hints of respective different source regions or release mechanisms of slow solar wind.

  14. PSS Controller for Wind Power Generation Systems

    Science.gov (United States)

    Domínguez-García, J. L.; Gomis-Bellmunt, O.; Bianchi, F.; Sumper, A.

    2012-10-01

    Small signal stability analysis for power systems with wind farm interaction is presented. Power systems oscillation modes can be excited by disturbance or fault in the grid. Variable speed wind turbines can be regulated to reduce these oscillations, stabilising the power system. A power system stabiliser (PSS) control loop for wind power is designed in order to increase the damping of the oscillation modes. The proposed power system stabiliser controller is evaluated by small signal analysis.

  15. WIND VARIABILITY IN BZ CAMELOPARDALIS

    International Nuclear Information System (INIS)

    Honeycutt, R. K.; Kafka, S.; Robertson, J. W.

    2013-01-01

    Sequences of spectra of the nova-like cataclysmic variable (CV) BZ Cam were acquired on nine nights in 2005-2006 in order to study the time development of episodes of wind activity known to occur frequently in this star. We confirm the results of Ringwald and Naylor that the P-Cygni absorption components of the lines mostly evolve from higher expansion velocity to lower velocity as an episode progresses. We also commonly find blueshifted emission components in the Hα line profile, whose velocities and durations strongly suggest that they are also due to the wind. Curiously, Ringwald and Naylor reported common occurrences of redshifted Hα emission components in their BZ Cam spectra. We have attributed these emission components in Hα to occasions when gas concentrations in the bipolar wind (both front side and back side) become manifested as emission lines as they move beyond the disk's outer edge. We also suggest, based on changes in the P-Cygni profiles during an episode, that the progression from larger to smaller expansion velocities is due to the higher velocity portions of a wind concentration moving beyond the edge of the continuum light of the disk first, leaving a net redward shift of the remaining absorption profile. We derive a new orbital ephemeris for BZ Cam, using the radial velocity of the core of the He I λ5876 line, finding P = 0.15353(4). Using this period, the wind episodes in BZ Cam are found to be concentrated near the inferior conjunction of the emission line source. This result helps confirm that the winds in nova-like CVs are often phase dependent, in spite of the puzzling implication that such winds lack axisymmetry. We argue that the radiation-driven wind in BZ Cam receives an initial boost by acting on gas that has been lifted above the disk by the interaction of the accretion stream with the disk, thereby imposing flickering timescales onto the wind events, as well as leading to an orbital modulation of the wind due to the non

  16. A general winding law of modular stellarator coils

    International Nuclear Information System (INIS)

    Harmeyer, E.; Kisslinger, J.; Rau, F.; Wobig, H.

    1985-03-01

    A general winding law for twisted coils is described in terms of analytic functions. On a toroidal surface given as x vector = x vector (φ,Θ) (φ = toroidal coordinate, Θ = poloidal coordinate) the current filaments φ = φ κ (Θ) are represented in terms of sin-functions. The paper includes several examples of classical stellarator and HELIAC configurations. By specifying a separate winding law for every single coil also WVII-AS type configurations can be modelled. The numerical code describing the central filament and the borderlines of the coils are given in the appendix. (orig.)

  17. Vermiform appendix within incisional hernia.

    Science.gov (United States)

    Kler, Aaron; Hossain, Naveed; Singh, Sandeep; Scarpinata, Rosaria

    2017-08-20

    The vermiform appendix (whether inflamed or not) within a hernia is very rare occurrence. We present the unprecedented case of a normal appendix found within a Pfannenstiel incisional hernia. A diagnostic laparoscopy was performed as appendicitis was suspected. However, the tip of a normal appendix was visualised within a previous Pfannenstiel incision. Laparoscopic appendicectomy was carried successfully and the patient was discharged. The patient later returned for a successful elective laparoscopic incisional hernia repair. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  18. Mucocele of the appendix.

    Science.gov (United States)

    Ruiz-Tovar, J; Teruel, D García; Castiñeiras, V Morales; Dehesa, A Sanjuanbenito; Quindós, P López; Molina, E Martínez

    2007-03-01

    Mucocele of the appendix is an infrequent event, representing 0.3%-0.7% of appendiceal pathology and 8% of appendiceal tumors. It is characterized by a located or diffuse distension of the appendix with a mucus-filled lumen. We describe 35 cases of mucocele of the appendix diagnosed at Ramón y Cajal Hospital between January 1985 and January 2006. A total of 21 males and 14 females with a mean age of 52.7 years are described. Most cases manifested as abdominal pain located in right iliac fossa, but 2 cases were incidental findings at CT-scan and 1 at ultrasonography, performed for other reasons. In 4 cases, mucocele coexisted with colorectal cancer and was an incidental finding during laparotomy performed for tumor resection. Ultrasonography and computed tomography (CT) scan helped to achieve a correct diagnosis. Preoperative diagnosis of mucocele was achieved in 29% of the cases; 88% of patients underwent appendectomy, 2 had ileocecal resection, and 2 others underwent right hemicolectomy. Pathology revealed mucous hyperplasia in 34% of the cases, simple mucocele in 29%, cystadenoma in 31%, and cystadenocarcinoma in 2 patients. Two other patients developed adenocarcinoma of the cecum 12 and 33 months after surgery, and one patient developed pseudomyxoma peritonei after 62 months, causing his death. The pathologist is forced to do an exhaustive study, looking for inadvertent perforations that can change the good prognosis of mucocele. We recommend follow-up of all patients with mucoceles, because sometimes they are associated with colorectal neoplasms and recurrence as pseudomyxoma peritonei.

  19. Wind Technologies & Evolving Opportunities (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Robichaud, R.

    2014-07-01

    This presentation covers opportunities for wind technology; wind energy market trends; an overview of the National Wind Technology Center near Boulder, Colorado; wind energy price and cost trends; wind turbine technology improvements; and wind resource characterization improvements.

  20. Design and Operation of Power Systems with Large Amounts of Wind Power: Final Summary Report, IEA WIND Task 25, Phase Three 2012-2014

    Energy Technology Data Exchange (ETDEWEB)

    Holttinen, Hannele; Kiviluoma, Juha; Forcione, Alain; Milligan, Michael; Smith, Charles J.; Dillon, Jody; Dobschinski, Jan; van Roon, Serafin; Cutululis, Nicolaos; Orths, Antje; Eriksen, Peter Borre; Carlini, Enrico Maria; Estanqueiro, Ana; Bessa, Ricardo; Soder, Lennart; Farahmand, Hossein; Torres, Jose Rueda; Jianhua, Bai; Kondoh, Junji; Pineda, Ivan; Strbac, Goran

    2016-06-01

    This report summarizes recent findings on wind integration from the 16 countries participating in the International Energy Agency (IEA) Wind collaboration research Task 25 in 2012-2014. Both real experience and studies are reported. The national case studies address several impacts of wind power on electric power systems. In this report, they are grouped under long-term planning issues and short-term operational impacts. Long-term planning issues include grid planning and capacity adequacy. Short-term operational impacts include reliability, stability, reserves, and maximizing the value in operational timescales (balancing related issues). The first section presents variability and uncertainty of power system-wide wind power, and the last section presents recent wind integration studies for higher shares of wind power. Appendix 1 provides a summary of ongoing research in the national projects contributing to Task 25 in 2015-2017.

  1. Wind Power Meteorology

    DEFF Research Database (Denmark)

    Lundtang Petersen, Erik; Mortensen, Niels Gylling; Landberg, Lars

    Wind power meteorology has evolved as an applied science, firmly founded on boundary-layer meteorology, but with strong links to climatology and geography. It concerns itself with three main areas: siting of wind turbines, regional wind resource assessment, and short-term prediction of the wind...... resource. The history, status and perspectives of wind power meteorology are presented, with emphasis on physical considerations and on its practical application. Following a global view of the wind resource, the elements of boundary layer meteorology which are most important for wind energy are reviewed......: wind profiles and shear, turbulence and gust, and extreme winds. The data used in wind power meteorology stem mainly from three sources: onsite wind measurements, the synoptic networks, and the re-analysis projects. Wind climate analysis, wind resource estimation and siting further require a detailed...

  2. Prospecting for Wind

    Science.gov (United States)

    Swapp, Andy; Schreuders, Paul; Reeve, Edward

    2011-01-01

    Many people use wind to help meet their needs. Over the years, people have been able to harness or capture the wind in many different ways. More recently, people have seen the rebirth of electricity-generating wind turbines. Thus, the age-old argument about technology being either good or bad can also be applied to the wind. The wind can be a…

  3. Careers in Wind Energy

    Science.gov (United States)

    Liming, Drew; Hamilton, James

    2011-01-01

    As a common form of renewable energy, wind power is generating more than just electricity. It is increasingly generating jobs for workers in many different occupations. Many workers are employed on wind farms: areas where groups of wind turbines produce electricity from wind power. Wind farms are frequently located in the midwestern, western, and…

  4. Intussusception of the vermiform appendix.

    Science.gov (United States)

    Dickson-Lowe, Richard A; Ibrahim, Sherine; Munthali, Lamios; Hasan, Fazal

    2015-07-16

    Appendicitis is a common presentation to an acute general surgical on call team. It can be a difficult diagnosis at times, particularly in sexually active young women, in whom it is often surgically challenging. This case is of a relatively straightforward diagnosis, taken for laparoscopic appendicectomy that resulted in performing an open right hemicolectomy for a necrotic, intussuscepted appendix. Histology ultimately revealed the cause of intussusception and resultant infarction of the appendix to be endometriosis. 2015 BMJ Publishing Group Ltd.

  5. Torsion of an appendix epiploica present at the vermiform appendix: a rare cause of acute abdomen.

    Science.gov (United States)

    Aslam, Muhammad Babar; Hasan, Noori

    2009-09-01

    An extremely rare case of torsion of an appendix epiploica attached to the vermiform appendix is reported in a 57-year-old male who presented with acute abdominal pain and tender right inguinal fossa. An infarcted appendix epiploica was seen attached near the tip of an otherwise unremarkable vermiform appendix through a narrow stalk. The histological examination revealed lobulated fibrofatty tissue showing congestion, acute inflammation and fat necrosis. The appendix was otherwise unremarkable.

  6. Prototype bucket foundation for wind turbines

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo; Liingaard, Morten

    The first full scale prototype bucket foundation for wind turbines has been installed in October 2002 at Aalborg University offshore test facility in Frederikshavn, Denmark. The suction caisson and the wind turbine have been equipped with an online monitoring system, consisting of 15 accelerometers...... estimates are then compared with numerical simulations of the suction caisson foundation and the wind turbine. The numerical model consists of a finite element section for the wind turbine tower and nacelle. The soil-structure interaction of the soil-foundation section is modelled by lumped-parameter models...

  7. Smart Grid in Denmark. Appendix report; Smart Grid i Danmark. Bilagsrapport

    Energy Technology Data Exchange (ETDEWEB)

    2010-07-01

    Electricity consumption and electricity production in Denmark will change significantly in future years. Electricity customers will demand new services in line with that they replace oil furnaces with electric heat pumps and the traditional petrol car with an electric car. The electricity sector must be ready to deliver those services with the same high delivery reliability as before. This must happen in a situation where power generation is increasingly coming from renewable energy. The purpose of the present analysis was to describe and analyse the specific challenges facing the electricity system in the next 15 to 25 years. Energinet.dk and the Danish Energy Association has analysed the part of the Smart Grid that enables an efficient interaction between wind power production, heat pumps in residential buildings as well as electric and plug-in hybrid cars. The appendix report describes the following issues: Scenarios for the power system's future loads; Optimisation of the power distribution grid for the future; Electro technical challenges in the future power grid; Components for handling the future challenges; Value of power system deliveries through establishing a Smart Grid; Economic analyses. (ln)

  8. UNIQUE 28 CM LONG VERMIFORM APPENDIX

    OpenAIRE

    Ravindra Kumar Boddeti; Roopa Kulkarni; Pradeep Kumar H Murudkar

    2013-01-01

    Vermiform appendix is a vestigial organ in human beings and situated at the ileocaecal junction. It opens into the caecum. It is a narrow tube of varying length. The normal, average length is about 5 cm to 10 cm. The longest vermiform appendix has been reported to be measuring about 25 cm. In the present case a long vermiform appendix was observed in female, formalin fixed, adult cadaver during the routine dissection for medical undergraduates. The Vermiform appendix was retrocaecal and exten...

  9. Influence of wind loading

    OpenAIRE

    MAVLONOV RAVSHANBEK ABDUJABBOROVICH; VAKKASOV KHAYRULLO SAYFULLAHANOVICH

    2015-01-01

    Each wind load is determined by a probabilistic-statistical method based on the concept of “equivalent static wind load”, on the assumption that structural frames and components/cladding behave elastically in strong wind.

  10. Tower Winds - Cape Kennedy

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Digitized data taken from Wind Gust Charts. Record contains hourly wind directions and speed with a peak wind recorded at the end of each day. Sorted by: station,...

  11. Wind energy program overview

    International Nuclear Information System (INIS)

    1992-02-01

    This overview emphasizes the amount of electric power that could be provided by wind power rather than traditional fossil fuels. New wind power markets, advances in technology, technology transfer, and wind resources are some topics covered in this publication

  12. Modelling Wind for Wind Farm Layout Optimization Using Joint Distribution of Wind Speed and Wind Direction

    OpenAIRE

    Ju Feng; Wen Zhong Shen

    2015-01-01

    Reliable wind modelling is of crucial importance for wind farm development. The common practice of using sector-wise Weibull distributions has been found inappropriate for wind farm layout optimization. In this study, we propose a simple and easily implementable method to construct joint distributions of wind speed and wind direction, which is based on the parameters of sector-wise Weibull distributions and interpolations between direction sectors. It is applied to the wind measurement data a...

  13. Denmark Wind Energy Programme

    DEFF Research Database (Denmark)

    Shen, Wen Zhong

    2014-01-01

    In this paper, a summary of some ongoing wind energy projects in Denmark is given. The research topics comprise computational model development, wind turbine design, low noise airfoil and blade design, control device development, wake modelling, and wind farm layout optimization.......In this paper, a summary of some ongoing wind energy projects in Denmark is given. The research topics comprise computational model development, wind turbine design, low noise airfoil and blade design, control device development, wake modelling, and wind farm layout optimization....

  14. Superconducting Wind Turbine Generators

    OpenAIRE

    Yunying Pan; Danhzen Gu

    2016-01-01

    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 ...

  15. Wind turbines, is it just wind?

    International Nuclear Information System (INIS)

    Boiteux, M.

    2012-01-01

    The author first outlines that wind energy is not only random, but almost absent in extreme situations when it would be needed (for example and notably, very cold weather without wind). He suggests the association of a gas turbine to each wind turbine, so that the gas turbine will replace non operating wind turbines. He notices that wind turbines are not proximity energy as they were said to be, and that profitability in fact requires tens of grouped giant wind turbines. He also outlines the high cost of construction of grids for the connection of these wind turbines. Thus, he states that wind energy is far from being profitable in the present conditions of electricity tariffs in France

  16. Prescribed wind shear modelling with the actuator line technique

    DEFF Research Database (Denmark)

    Mikkelsen, Robert Flemming; Sørensen, Jens Nørkær; Troldborg, Niels

    2007-01-01

    A method for prescribing arbitrary steady atmospheric wind shear profiles combined with CFD is presented. The method is furthermore combined with the actuator line technique governing the aerodynamic loads on a wind turbine. Computation are carried out on a wind turbine exposed to a representative...... steady atmospheric wind shear profile with and without wind direction changes up through the atmospheric boundary layer. Results show that the main impact on the turbine is captured by the model. Analysis of the wake behind the wind turbine, reveal the formation of a skewed wake geometry interacting...

  17. Advanced structural wind engineering

    CERN Document Server

    Kareem, Ahsan

    2013-01-01

    This book serves as a textbook for advanced courses as it introduces state-of-the-art information and the latest research results on diverse problems in the structural wind engineering field. The topics include wind climates, design wind speed estimation, bluff body aerodynamics and applications, wind-induced building responses, wind, gust factor approach, wind loads on components and cladding, debris impacts, wind loading codes and standards, computational tools and computational fluid dynamics techniques, habitability to building vibrations, damping in buildings, and suppression of wind-induced vibrations. Graduate students and expert engineers will find the book especially interesting and relevant to their research and work.

  18. The assessment and rating of noise from wind farms. Final report

    International Nuclear Information System (INIS)

    1996-09-01

    The findings of a Working Group on Wind Turbine Noise in the United Kingdom are presented. The broad topics covered are: the philosophy and practice of noise emission control; description of noise emission from wind turbines; a review of current practice and guidance; a survey of public reaction to noise from wind farms; recommendations on noise limits; noise monitoring; the planning obligation. In deriving suggested noise limits, a reasonable degree of protection to wind farm neighbours has been sought which will not place unreasonable restrictions and undue added costs and administrative burdens on wind farm developers or local authorities. Examples of practice in the control of noise emissions at wind farms in the United Kingdom and the USA are assembled in an Appendix. (29 figures; 13 tables; 32 references) (UK)

  19. The dune effect on sand-transporting winds on Mars

    Science.gov (United States)

    Jackson, Derek W. T.; Bourke, Mary C.; Smyth, Thomas A. G.

    2015-11-01

    Wind on Mars is a significant agent of contemporary surface change, yet the absence of in situ meteorological data hampers the understanding of surface-atmospheric interactions. Airflow models at length scales relevant to landform size now enable examination of conditions that might activate even small-scale bedforms (ripples) under certain contemporary wind regimes. Ripples have the potential to be used as modern `wind vanes' on Mars. Here we use 3D airflow modelling to demonstrate that local dune topography exerts a strong influence on wind speed and direction and that ripple movement likely reflects steered wind direction for certain dune ridge shapes. The poor correlation of dune orientation with effective sand-transporting winds suggests that large dunes may not be mobile under modelled wind scenarios. This work highlights the need to first model winds at high resolution before inferring regional wind patterns from ripple movement or dune orientations on the surface of Mars today.

  20. Congenital absence of the vermiform appendix.

    Science.gov (United States)

    Sarkar, Aniruddha

    2012-09-01

    Agenesis of the vermiform appendix is very rare. The incidence is estimated to be one in 100,000 laparotomies for suspected appendicitis. During a routine dissection of the abdomen in a 60-year-old donated male cadaver, the vermiform appendix was found to be absent. The ileocaecal junction and retrocaecal area were thoroughly searched, but the vermiform appendix was not found or appeared to resemble a tubercle. This is likely the first reported case of agenesis of a vermiform appendix in India. This suggests the possibility that the human vermiform appendix would ultimately become rudimentary or absent in the course of evolution.

  1. NEOPLASTIC LESIONS OF THE APPENDIX

    Directory of Open Access Journals (Sweden)

    Piotr Bryk

    2013-11-01

    Full Text Available The aim of the research was to present the clinical observations of neoplastic lesions of the appendix (one carcinoid and two mucous cysts and to discuss various manners of treatment and prognosis. Material and methods: The authors of the following paper present a description of three cases of appendix tumours, two patients with a mucous cyst and a patient with carcinoid, against the background of all the appendectomies performed at the Clinical Department of General, Endocrine and Oncological Surgery of the Provincial Polyclinical Hospital in Kielce in the years 2005–2011. Results : Within the 7-year period, a total of 11 719 surgical operations have been performed, where 834 (7.1% were that of appendectomy. Among all of the removed vermiform appendixes, neoplastic lesions occurred in three cases constituting a mere 0.3% of all of the appendectomies performed within that period. In two of the cases there was a suspicion of mucous cysts before the surgical operation. In none of the above-mentioned cases was is possible to ultimately establish the diagnosis before the operation. The patients were subjected to a simple appendectomy. The patients are in good clinical health, with no signs of relapse. Conclusions : The presented cases of patients with appendix tumours illustrate the difficulty of preoperative detection of a neoplastic lesion. This is mainly due to a scantily symptomatic course or symptoms typical of appendicitis. In light of this, histopathological examination of each appendix should be treated as obligatory.

  2. Wind engineering in Africa

    NARCIS (Netherlands)

    Wisse, J.A.; Stigter, C.J.

    2007-01-01

    The International Association for Wind Engineering (IAWE) has very few contacts in Africa, the second-largest continent. This paper reviews important wind-related African issues. They all require data on wind climate, which are very sparse in Africa. Wind engineering in Africa can assist in

  3. Wind energy; Energie eolienne

    Energy Technology Data Exchange (ETDEWEB)

    Vachey, C.

    2000-05-01

    This public information paper presents the wind energy resource in the Languedoc Roussillon region, explains how a wind turbine works, the different types of utilization and the cost of the wind energy. The environmental impacts of the wind energy, on the noise and the landscape, are also discussed. (A.L.B.)

  4. Offshore Wind Farms

    DEFF Research Database (Denmark)

    Lundtang Petersen, Erik; Hasager, Charlotte Bay; Courtney, Michael

    2015-01-01

    The technology behind constructing wind farms offshore began to develop in 1991 when the Vindeby wind farm was installed off the Danish coast (11 Bonus 450 kW turbines). Resource assessment, grid connection, and wind farm operation are significant challenges for offshore wind power just...... concern are the problems associated with locating the turbines close together in a wind farm and the problems of placing several large wind farms in a confined area. The environmental impacts of offshore wind farms are also treated, but not the supply chain, that is, the harbors, the installation vessels...

  5. WIND PROTECTION OF LANDSCAPE ARCHITECTURE

    Directory of Open Access Journals (Sweden)

    Trubitsyna Natalja Anatolevna

    2017-07-01

    Full Text Available The article discusses the interaction between the wind regime and the landscape. Examples of objects of landscape architecture in high-tech and science-intensive spheres, such as the launch pad of a spacecraft, are given. Wind protection is represented as a result of work on wind power engineering and a means of increasing bioclimatic comfort. The terms of landscape architecture are disclosed and mutual influence on the climate and impact on woody-shrub vegetation and field crops are analyzed. The phenomenon of air permeability for optimal operation of windproof structures and orientations of geoplastics and dendroplastics is described. In this paper, a classification of terrain types is described with a description of their elemental composition, as well as various categories of landscape. The proposal to consider the landscape as a territorial complex, and landscape buildings, landscape-architectural structures as objects of landscape architecture possessing properties of wind protection and air permeability was introduced. Thus, the concept of a landscape-architectural complex as a single group of landscape-architectural objects located on the territory and connected by a common system of communications, functions, technical elements and a visual image is formulated. Further research is based on the rationale for the use of the term ensemble in relation to the objects of the landscape and architectural complex and the identification of their design and planning features that can affect the parameters of wind protection and air permeability. The paper concludes that frequent coincidence of favorable for the fauna wind regime and mimicry of landscape architecture objects. The combination in the landscape of functions for wind protection and aesthetics is analyzed with analysis of such elements of landscape architecture as hedges and windproof properties of green plantations. In the work examples of wind engineering small architectural forms are

  6. Introducing WISDEM:An Integrated System Modeling for Wind Turbines and Plant (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Dykes, K.; Graf, P.; Scott, G.; Ning, A.; King, R.; Guo, Y.; Parsons, T.; Damiani, R.; Felker, F.; Veers, P.

    2015-01-01

    The National Wind Technology Center wind energy systems engineering initiative has developed an analysis platform to leverage its research capabilities toward integrating wind energy engineering and cost models across wind plants. This Wind-Plant Integrated System Design & Engineering Model (WISDEM) platform captures the important interactions between various subsystems to achieve a better National Wind Technology Center wind energy systems engineering initiative has developed an analysis platform to leverage its research capabilities toward integrating wind energy engineering and cost models across wind plants. This Wind-Plant Integrated System Design & Engineering Model (WISDEM) platform captures the important interactions between various subsystems to achieve a better understanding of how to improve system-level performance and achieve system-level cost reductions. This work illustrates a few case studies with WISDEM that focus on the design and analysis of wind turbines and plants at different system levels.

  7. Wind power. [electricity generation

    Science.gov (United States)

    Savino, J. M.

    1975-01-01

    A historical background on windmill use, the nature of wind, wind conversion system technology and requirements, the economics of wind power and comparisons with alternative systems, data needs, technology development needs, and an implementation plan for wind energy are presented. Considerable progress took place during the 1950's. Most of the modern windmills feature a wind turbine electricity generator located directly at the top of their rotor towers.

  8. Flow adjustment inside large finite-size wind farms approaching the infinite wind farm regime

    Science.gov (United States)

    Wu, Ka Ling; Porté-Agel, Fernando

    2017-04-01

    Due to the increasing number and the growing size of wind farms, the distance among them continues to decrease. Thus, it is necessary to understand how these large finite-size wind farms and their wakes could interfere the atmospheric boundary layer (ABL) dynamics and adjacent wind farms. Fully-developed flow inside wind farms has been extensively studied through numerical simulations of infinite wind farms. The transportation of momentum and energy is only vertical and the advection of them is neglected in these infinite wind farms. However, less attention has been paid to examine the length of wind farms required to reach such asymptotic regime and the ABL dynamics in the leading and trailing edges of the large finite-size wind farms. Large eddy simulations are performed in this study to investigate the flow adjustment inside large finite-size wind farms in conventionally-neutral boundary layer with the effect of Coriolis force and free-atmosphere stratification from 1 to 5 K/km. For the large finite-size wind farms considered in the present work, when the potential temperature lapse rate is 5 K/km, the wind farms exceed the height of the ABL by two orders of magnitude for the incoming flow inside the farms to approach the fully-developed regime. An entrance fetch of approximately 40 times of the ABL height is also required for such flow adjustment. At the fully-developed flow regime of the large finite-size wind farms, the flow characteristics match those of infinite wind farms even though they have different adjustment length scales. The role of advection at the entrance and exit regions of the large finite-size wind farms is also examined. The interaction between the internal boundary layer developed above the large finite-size wind farms and the ABL under different potential temperature lapse rates are compared. It is shown that the potential temperature lapse rate plays a role in whether the flow inside the large finite-size wind farms adjusts to the fully

  9. Solar wind interaction with Mars' upper atmosphere: Results from 3-D studies using one-way coupling between the Multi-fluid MHD, the M-GITM and the AMPS models

    Science.gov (United States)

    Dong, C.; Bougher, S. W.; Ma, Y.; Toth, G.; Lee, Y.; Nagy, A. F.; Tenishev, V.; Pawlowski, D. J.; Meng, X.; Combi, M. R.

    2013-12-01

    The study of the solar wind interaction with Mars upper atmosphere/ionosphere has triggered a great of interest in recent years. Among the large number of topics in this research area, the investigation of ion escape fluxes has become increasingly important due to its potential impact on the long-term evolution of Mars atmosphere (e.g., loss of water) over its history. In the present work, we adopt the 3-D Mars cold neutral atmosphere profiles (0~300 km) from the newly developed and validated Mars Global Ionosphere Thermosphere Model (M-GITM) and the 3-D hot oxygen profiles (100km~5RM) from the exosphere Monte Carlo model Adaptive Mesh Particle Simulator (AMPS). We apply these 3-D model outputs fields into the 3-D BATS-R-US Mars multi-fluid MHD model (100km~20RM) that can better simulate the interplay between Mars upper atmosphere and solar wind by considering the dynamics of individual ion species. The multi-fluid model solves separate continuity, momentum and energy equations for each ion species (H+, O+, O2+, CO2+). The M-GITM model together with the AMPS exosphere model take into account the effects of solar cycle and seasonal variations on both cold and hot neutral atmospheres, allowing us to investigate the corresponding effects on the Mars upper atmosphere ion escape by using a one-way coupling approach, i.e., both the M-GITM and AMPS model outputs are used as the inputs for the multi-fluid model and M-GITM is used as input into the AMPS exosphere model. The calculations are carried out for selected cases with different nominal solar wind, solar cycle and crustal field orientation conditions. This work has the potential to provide predictions of ion escape rates for comparison to future data to be returned by the MAVEN primary mission (2014-2016) and thereby improve our understanding of present day escape processes. Acknowledgments: The work presented here was supported by NASA grants NNH10CC04C, NNX09AL26G, NSF grant ATM-0535811.

  10. Wind regimes derived from martian large ripples: Implications for long-term and short-term wind dynamics

    Science.gov (United States)

    Liu, Z. Y. C.; Zimbelman, J. R.; Fenton, L. K.

    2016-12-01

    Aeolian bedforms, such as sand dunes and wind ripples, have been extensively used to derive surface wind regimes on Mars. However, the distinction of different temporal (i.e., long-term vs. short-term) and spatial (i.e., global vs. local) scales of surface winds derived from these bedforms is unclear. In addition, many recent studies have utilized various scales of numeric modeling, such as global scale general circulation models, mesoscale, and microscale airflow models, to analyze surface wind regimes based on aeolian features and compare the modeled winds with those derived from mapping of dunes and ripples. These results showed some degree of discrepancy between mapping-inferred winds and modeled winds, which may be in part due to the lack of recognition of different scales of winds. Since the knowledge of possible wind patterns is essential to understanding past and present climate on Mars, this study aims to classify the types of surface wind derived from different aeolian features. Here we use large martian ripples as indicators to infer near-surface wind regimes, following an approach previously developed by us. We then compare the ripple-inferred winds with those derived from both dune slipfaces and crestline alignments, using IMGBNT (inverse maximum gross bedform-normal transport) and IMSF (inverse mean sand flux) techniques. Our initial results show that ripple-inferred wind regimes are consistent with either dune crestline orientations or slipface-inferred wind regimes. The former implies the interaction between airflow and dune crest topography (i.e., form-flow), which produces the longitudinal winds, whereas the slipface-inferred winds are most likely transverse in nature. Furthermore, our results suggest that dune slipface and large ripples may better reflect local-scale, short-period wind dynamics, whereas dune alignment may better reflects large-scale, long-period wind dynamics. Thus, comparison of wind regimes using numeric modeling should be

  11. Appendix D of the Final Report of the Mid-Atlantic Marine Wildlife Surveys, Modeling, and Data. Workshop to Establish Coordination and Communication

    Energy Technology Data Exchange (ETDEWEB)

    None

    2013-07-01

    The Wind Program hosted a two-day workshop on July 24-25, 2012 with scientists and regulators engaged in marine ecological survey, modeling, and database efforts pertaining to the waters of the Mid-Atlantic region. This is the fourth appendix to the report, the presentations from the workshop.

  12. Streptococcus milleri in the appendix.

    Science.gov (United States)

    Poole, P M; Wilson, G

    1977-10-01

    The appendix was investigated as a possible habitat of Streptococcus milleri. Both normal and inflamed appendices were examined and the isolation rates compared. S. milleri was present in a quarter of the normal appendices and more than half of those associated with apendicitis--a difference that was statistically highly significant. The isolation rates throughout were indepencent of age. There was a pronounced connection between the presence of S. milleri in the appendix and the purulent manifestations of appendicitis. S. milleri was isolated from other abdominal sites associated with appendicitis. The frequency of isolation was increased by culture in an enrichment broth containing nalidixic acid and sulphadimidine.

  13. Multifractal and local correlation of simultaneous wind speed-power output from a single wind trubine

    Science.gov (United States)

    Calif, Rudy; Schmitt, François G.; Huang, Yongxiang

    2014-05-01

    The wind energy production is a nonlinear and no stationary resource, due to the intermittent statistics of atmospheric wind speed at all spatial and temporal scales ranging from large scale variations to very short scale variations. Recently, Rudy et al.[1] observed the intermittent and multifractal properties of wind energy production. Classically, IEC standard 4100 is used by the wind energy community, for modeling the interactions of wind speed with the wind turbine. However, this model reflects gaussian statistics contrary to observed wind and energy production measurements. Modeling of power curve of a single wind turbine remains a challenge. The precise understanding of the dynamics of nonlinear power curve over very short time scales, is necessary. Hence, multifractal cross-correlation methods such as Generalized Correlations Exponents (GCE), multifractal detrended cross-correlation analysis (MFXDFA), multifractal detrending moving average cross-correlation analysis (MFXDMA) are applied to simultaneous wind speed power output from a single wind turbine to determine the nature of scaling correlation behavior. Furthermore, in order to detect eventual local correlation, an application of empirical mode decomposition based on time dependent intrinsic correlation to simultaneous measurements is performed. The simultaneous wind speed-power output measurements are recorded continuously with a sampling rate f = 1Hz, during 115 days in 2006. The wind speed measurements are obtained at 31 m above the ground, and the power output is delivered by 500 kW Nordtank wind turbine positionned at the Technical University, Risœ, Denmark. References [1] Calif, R., Schmitt, F.G., Huang, Y., Multifractal description of wind power fluctuations using arbitrary order Hilbert spectral analysis, Physica, 392, 4106-4120, 2013.

  14. A new method for wind speed forecasting based on copula theory.

    Science.gov (United States)

    Wang, Yuankun; Ma, Huiqun; Wang, Dong; Wang, Guizuo; Wu, Jichun; Bian, Jinyu; Liu, Jiufu

    2018-01-01

    How to determine representative wind speed is crucial in wind resource assessment. Accurate wind resource assessments are important to wind farms development. Linear regressions are usually used to obtain the representative wind speed. However, terrain flexibility of wind farm and long distance between wind speed sites often lead to low correlation. In this study, copula method is used to determine the representative year's wind speed in wind farm by interpreting the interaction of the local wind farm and the meteorological station. The result shows that the method proposed here can not only determine the relationship between the local anemometric tower and nearby meteorological station through Kendall's tau, but also determine the joint distribution without assuming the variables to be independent. Moreover, the representative wind data can be obtained by the conditional distribution much more reasonably. We hope this study could provide scientific reference for accurate wind resource assessments. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Closure of multi-fluid and kinetic equations for cyclotron-resonant interactions of solar wind ions with Alfvén waves

    Directory of Open Access Journals (Sweden)

    E. Marsch

    1998-01-01

    Full Text Available Based on quasilinear theory, a closure scheme for anisotropic multi-component fluid equations is developed for the wave-particle interactions of ions with electromagnetic Alfvén and ion-cyclotron waves propagating along the mean magnetic field. Acceleration and heating rates are calculated. They may be used in the multi-fluid momentum and energy equations as anomalous transport terms. The corresponding evolution equation for the average wave spectrum is established, and the effective growth/damping rate for the spectrum is calculated. Given a simple power-law spectrum, an anomalous collision frequency can be derived which depends on the slope and average intensity of the spectrum, and on the gyrofrequency and the differential motion (with respect to the wave frame of the actual ion species considered. The wave-particle interaction terms attain simple forms resembling the ones for collisional friction and temperature anisotropy relaxation (due to pitch angle scattering with collision rates that are proportional to the gyrofrequency but diminished substantially by the relative wave energy or the fluctuation level with respect the background field. In addition, a set of quasilinear diffusion equations is derived for the reduced (with respect to the perpendicular velocity component velocity distribution functions (VDFs, as they occur in the wave dispersion equation and the related dielectric function for parallel propagation. These reduced VDFs allow one to describe adequately the most prominent observed features, such as an ion beam and temperature anisotropy, in association with the resonant interactions of the particles with the waves on a kinetic level, yet have the advantage of being only dependent upon the parallel velocity component.

  16. Economic optimization of offshore wind farms

    International Nuclear Information System (INIS)

    Pauling, T.

    1996-09-01

    The study on the title subject continues the development of a cost model for offshore wind farms started at the Institute for Wind Energy (IW) in 1995, and applies it on different kinds of cost analyses. The model will be considered within the European research project 'Structural and Economic Optimization of Bottom-Mounted Offshore Wind Energy Converters' (Opti-OWECS, JOR3-CT95-0087) co-ordinated by the IW, where also the cost analyses and optimization will be extended. The conclusions of the investigations have already been presented at the European Union Wind Energy Conference '96 at Goeteborg, Sweden. In Chapter 1, a short overview of former offshore studies and projects is given, especially those dealing with cost analysis. Typical cost breakdowns of offshore and onshore wind farms are compared. Chapter 2 contains a brief description of the cost model in its present state. The recent improvements and extensions are documented in Chapter 3, and a validation by means of a recalculation of two former offshore studies is carried out in Chapter 4. In Chapter 5, four different offshore sites are compared with respect to the same farm size and an optimized farm design: Jade in the German part of the North Sea near Wilhelmshafen; Swansea Bay in the Bristol Channel at the British Atlantic Coast; Rostock at the German Baltic Coast, and IJmuiden in the Dutch part of the North Sea. In Chapter 6, a sensitivity study is carried out for a variety of site, design and economical parameters. The results of this project are summarized in Chapter 7, and an outlook is given in Chapter 8. The appendix contains among others a description of the SCOptiM2 code, where the model is implemented, as well as data obtained from the parameter studies and design optimizations. 30 figs., 8 tabs., 6 appendices, 40 refs

  17. Wind Energy Program overview, Fiscal year 1993

    Energy Technology Data Exchange (ETDEWEB)

    1994-05-01

    Wind energy research has two goals: (1) to gain a fundamental understanding of the interactions between wind and wind turbines; and (2) to develop the basic design tools required to develop advanced technologies. A primary objective of applied research activities is to develop sophisticated computer codes and integrate them into the design, testing, and evaluation of advanced components and systems, Computer models have become a necessary and integral part of developing new high-tech wind energy systems. A computer-based design strategy allows designers to model different configurations and explore new designs before building expensive hardware. DOE works closely with utilities and the wind industry in setting its applied research agenda. As soon as research findings become available, the national laboratories transfer the information to industry through workshops, conferences, and publications.

  18. Climatic wind tunnel for wind engineering tasks

    Czech Academy of Sciences Publication Activity Database

    Kuznetsov, Sergeii; Pospíšil, Stanislav; Král, Radomil

    2015-01-01

    Roč. 112, 2-B (2015), s. 303-316 ISSN 1897-628X R&D Projects: GA ČR(CZ) GA14-12892S Keywords : climatic tunnel * wind tunnel * atmospheric boundary layer * flow resistance * wind tunnel contraction Subject RIV: JM - Building Engineering https://suw.biblos.pk.edu.pl/resources/i5/i6/i6/i7/i6/r56676/KuznetsovS_ClimaticWind.pdf

  19. Wind Atlas for Egypt

    DEFF Research Database (Denmark)

    Mortensen, Niels Gylling; Said Said, Usama; Badger, Jake

    2006-01-01

    The results of a comprehensive, 8-year wind resource assessment programme in Egypt are presented. The objective has been to provide reliable and accurate wind atlas data sets for evaluating the potential wind power output from large electricityproducing wind turbine installations. The regional wind...... climates of Egypt have been determined by two independent methods: a traditional wind atlas based on observations from more than 30 stations all over Egypt, and a numerical wind atlas based on long-term reanalysis data and a mesoscale model (KAMM). The mean absolute error comparing the two methods is about...... 10% for two large-scale KAMM domains covering all of Egypt, and typically about 5% for several smaller-scale regional domains. The numerical wind atlas covers all of Egypt, whereas the meteorological stations are concentrated in six regions. The Wind Atlas for Egypt represents a significant step...

  20. Wind Atlas for Egypt

    DEFF Research Database (Denmark)

    The results of a comprehensive, 8-year wind resource assessment programme in Egypt are presented. The objective has been to provide reliable and accurate wind atlas data sets for evaluating the potential wind power output from large electricityproducing wind turbine installations. The regional wind...... climates of Egypt have been determined by two independent methods: a traditional wind atlas based on observations from more than 30 stations all over Egypt, and a numerical wind atlas based on long-term reanalysis data and a mesoscale model (KAMM). The mean absolute error comparing the two methods is about...... 10% for two large-scale KAMM domains covering all of Egypt, and typically about 5% for several smaller-scale regional domains. The numerical wind atlas covers all of Egypt, whereas the meteorological stations are concentrated in six regions. The Wind Atlas for Egypt represents a significant step...

  1. Extreme wind estimate for Hornsea wind farm

    DEFF Research Database (Denmark)

    Larsén, Xiaoli Guo

    The purpose of this study is to provide estimation of the 50-year winds of 10 min and 1-s gust value at hub height of 100 m, as well as the design parameter shear exponent for the Hornsea offshore wind farm. The turbulence intensity required for estimating the gust value is estimated using two ap....... The greatest sector-wise extreme winds are from west to northwest. Different data, different periods and different methods have provided a range of values of the 50-year wind and accordingly the gust values, as summarized in Table 15.......The purpose of this study is to provide estimation of the 50-year winds of 10 min and 1-s gust value at hub height of 100 m, as well as the design parameter shear exponent for the Hornsea offshore wind farm. The turbulence intensity required for estimating the gust value is estimated using two...... approaches. One is through the measurements from the wind Doppler lidar, WindCube, which implies serious uncertainty, and the other one is through similarity theory for the atmospheric surface layer where the hub height is likely to belong to during strong storms. The turbulence intensity for storm wind...

  2. Offshore wind energy developments

    DEFF Research Database (Denmark)

    Stolpe, Mathias; Buhl, Thomas; Sumer, B. Mutlu

    2014-01-01

    This chapter will give a brief overview of a few of the activities within offshore wind energy research, specifically 1) Support structure optimization, 2) Blade coatings for wind turbines; 3) Scour protection of foundations, 4) Offshore HVDC and 5) Offshore wind services.......This chapter will give a brief overview of a few of the activities within offshore wind energy research, specifically 1) Support structure optimization, 2) Blade coatings for wind turbines; 3) Scour protection of foundations, 4) Offshore HVDC and 5) Offshore wind services....

  3. Wind energy information guide

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-04-01

    This book is divided into nine chapters. Chapters 1--8 provide background and annotated references on wind energy research, development, and commercialization. Chapter 9 lists additional sources of printed information and relevant organizations. Four indices provide alphabetical access to authors, organizations, computer models and design tools, and subjects. A list of abbreviations and acronyms is also included. Chapter topics include: introduction; economics of using wind energy; wind energy resources; wind turbine design, development, and testing; applications; environmental issues of wind power; institutional issues; and wind energy systems development.

  4. Wind Power Career Chat

    Energy Technology Data Exchange (ETDEWEB)

    2011-01-01

    This document will teach students about careers in the wind energy industry. Wind energy, both land-based and offshore, is expected to provide thousands of new jobs in the next several decades. Wind energy companies are growing rapidly to meet America's demand for clean, renewable, and domestic energy. These companies need skilled professionals. Wind power careers will require educated people from a variety of areas. Trained and qualified workers manufacture, construct, operate, and manage wind energy facilities. The nation will also need skilled researchers, scientists, and engineers to plan and develop the next generation of wind energy technologies.

  5. Arctic wind energy

    International Nuclear Information System (INIS)

    Peltola, E.; Holttinen, H.; Marjaniemi, M.; Tammelin, B.

    1998-01-01

    Arctic wind energy research was aimed at adapting existing wind technologies to suit the arctic climatic conditions in Lapland. Project research work included meteorological measurements, instrument development, development of a blade heating system for wind turbines, load measurements and modelling of ice induced loads on wind turbines, together with the development of operation and maintenance practices in arctic conditions. As a result the basis now exists for technically feasible and economically viable wind energy production in Lapland. New and marketable products, such as blade heating systems for wind turbines and meteorological sensors for arctic conditions, with substantial export potential, have also been developed. (orig.)

  6. Arctic wind energy

    Energy Technology Data Exchange (ETDEWEB)

    Peltola, E. [Kemijoki Oy (Finland); Holttinen, H.; Marjaniemi, M. [VTT Energy, Espoo (Finland); Tammelin, B. [Finnish Meteorological Institute, Helsinki (Finland)

    1998-12-31

    Arctic wind energy research was aimed at adapting existing wind technologies to suit the arctic climatic conditions in Lapland. Project research work included meteorological measurements, instrument development, development of a blade heating system for wind turbines, load measurements and modelling of ice induced loads on wind turbines, together with the development of operation and maintenance practices in arctic conditions. As a result the basis now exists for technically feasible and economically viable wind energy production in Lapland. New and marketable products, such as blade heating systems for wind turbines and meteorological sensors for arctic conditions, with substantial export potential, have also been developed. (orig.)

  7. Wind power today

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-04-01

    This publication highlights initiatives of the US DOE`s Wind Energy Program. 1997 yearly activities are also very briefly summarized. The first article describes a 6-megawatt wind power plant installed in Vermont. Another article summarizes technical advances in wind turbine technology, and describes next-generation utility and small wind turbines in the planning stages. A village power project in Alaska using three 50-kilowatt turbines is described. Very brief summaries of the Federal Wind Energy Program and the National Wind Technology Center are also included in the publication.

  8. Appendix C: safety design rationale

    International Nuclear Information System (INIS)

    Ghose, S.

    1985-01-01

    A brief discussion of the rationale for safety design of fusion plants is presented in the main text. Further detail safety considerations are presented in this appendix in the form of charts and tables. The author present some of the major safety criteria and other criteria used in blanket selection here

  9. CubeSat Constellation Cloud Winds(C3Winds) A New Wind Observing System to Study Mesoscale Cloud Dynamics and Processes

    Science.gov (United States)

    Wu, D. L.; Kelly, M.A.; Yee, J.-H.; Boldt, J.; Demajistre, R.; Reynolds, E. L.; Tripoli, G. J.; Oman, L. D.; Prive, N.; Heidinger, A. K.; hide

    2016-01-01

    The CubeSat Constellation Cloud Winds (C3Winds) is a NASA Earth Venture Instrument (EV-I) concept with the primary objective to better understand mesoscale dynamics and their structures in severe weather systems. With potential catastrophic damage and loss of life, strong extratropical and tropical cyclones (ETCs and TCs) have profound three-dimensional impacts on the atmospheric dynamic and thermodynamic structures, producing complex cloud precipitation patterns, strong low-level winds, extensive tropopause folds, and intense stratosphere-troposphere exchange. Employing a compact, stereo IR-visible imaging technique from two formation-flying CubeSats, C3Winds seeks to measure and map high-resolution (2 km) cloud motion vectors (CMVs) and cloud geometric height (CGH) accurately by tracking cloud features within 5-15 min. Complementary to lidar wind observations from space, the high-resolution wind fields from C3Winds will allow detailed investigations on strong low-level wind formation in an occluded ETC development, structural variations of TC inner-core rotation, and impacts of tropopause folding events on tropospheric ozone and air quality. Together with scatterometer ocean surface winds, C3Winds will provide a more comprehensive depiction of atmosphere-boundary-layer dynamics and interactive processes. Built upon mature imaging technologies and long history of stereoscopic remote sensing, C3Winds provides an innovative, cost-effective solution to global wind observations with potential of increased diurnal sampling via CubeSat constellation.

  10. Transient LES of an offshore wind turbine

    Directory of Open Access Journals (Sweden)

    L. Vollmer

    2017-12-01

    Full Text Available The estimation of the cost of energy of offshore wind farms has a high uncertainty, which is partly due to the lacking accuracy of information on wind conditions and wake losses inside of the farm. Wake models that aim to reduce the uncertainty by modeling the wake interaction of turbines for various wind conditions need to be validated with measurement data before they can be considered as a reliable estimator. In this paper a methodology that enables a direct comparison of modeled with measured flow data is evaluated. To create the simulation data, a model chain including a mesoscale model, a large-eddy-simulation (LES model and a wind turbine model is used. Different setups are compared to assess the capability of the method to reproduce the wind conditions at the hub height of current offshore wind turbines. The 2-day-long simulation of the ambient wind conditions and the wake simulation generally show good agreements with data from a met mast and lidar measurements, respectively. Wind fluctuations due to boundary layer turbulence and synoptic-scale motions are resolved with a lower representation of mesoscale fluctuations. Advanced metrics to describe the wake shape and development are derived from simulations and measurements but a quantitative comparison proves to be difficult due to the scarcity and the low sampling rate of the available measurement data. Due to the implementation of changing synoptic wind conditions in the LES, the methodology could also be beneficial for case studies of wind farm performance or wind farm control.

  11. Methods and apparatus for cooling wind turbine generators

    Science.gov (United States)

    Salamah, Samir A [Niskayuna, NY; Gadre, Aniruddha Dattatraya [Rexford, NY; Garg, Jivtesh [Schenectady, NY; Bagepalli, Bharat Sampathkumaran [Niskayuna, NY; Jansen, Patrick Lee [Alplaus, NY; Carl, Jr., Ralph James

    2008-10-28

    A wind turbine generator includes a stator having a core and a plurality of stator windings circumferentially spaced about a generator longitudinal axis. A rotor is rotatable about the generator longitudinal axis, and the rotor includes a plurality of magnetic elements coupled to the rotor and cooperating with the stator windings. The magnetic elements are configured to generate a magnetic field and the stator windings are configured to interact with the magnetic field to generate a voltage in the stator windings. A heat pipe assembly thermally engaging one of the stator and the rotor to dissipate heat generated in the stator or rotor.

  12. 2012 Wind Program Peer Review Report

    Energy Technology Data Exchange (ETDEWEB)

    Zayas, Jose [Energy Efficiencey and Renewable Energy (EERE), Washington, DC (United States); Higgins, Mark [Energy Efficiencey and Renewable Energy (EERE), Washington, DC (United States)

    2012-06-01

    This report summarizes the proceedings of the 2012 Wind Program Peer Review, the goals of which were to review and evaluate the strategy and goals of the Wind Program; review and evaluate the progress and accomplishments of the program's projects funded in fiscal year (FY) 2010 and FY 2011; and foster interactions among the national laboratories, industry, and academic institutions conducting research and development on behalf of the program.

  13. Lidar - Wind, Raman, and Other Sensing

    OpenAIRE

    Rocadenbosch Burillo, Francisco

    2003-01-01

    Lidar stands for Llght Detection and Ranging. Laser radars or lidars, which are optically the closest counterparts of conventional rnicrowave radars, take advantage of the relatively strong interaction of laser light with atmospheric constituents. They offer superior spatial and temporal resolution and are effective remote sensing instruments. Wind, Raman, and other lidar sensing instruments encompass a wide range of systems-unprecedented long-range wind, aerosol, and molecular chemical...

  14. Ocean Wave Simulation Based on Wind Field.

    Science.gov (United States)

    Li, Zhongyi; Wang, Hao

    2016-01-01

    Ocean wave simulation has a wide range of applications in movies, video games and training systems. Wind force is the main energy resource for generating ocean waves, which are the result of the interaction between wind and the ocean surface. While numerous methods to handle simulating oceans and other fluid phenomena have undergone rapid development during the past years in the field of computer graphic, few of them consider to construct ocean surface height field from the perspective of wind force driving ocean waves. We introduce wind force to the construction of the ocean surface height field through applying wind field data and wind-driven wave particles. Continual and realistic ocean waves result from the overlap of wind-driven wave particles, and a strategy was proposed to control these discrete wave particles and simulate an endless ocean surface. The results showed that the new method is capable of obtaining a realistic ocean scene under the influence of wind fields at real time rates.

  15. Ocean Wave Simulation Based on Wind Field.

    Directory of Open Access Journals (Sweden)

    Zhongyi Li

    Full Text Available Ocean wave simulation has a wide range of applications in movies, video games and training systems. Wind force is the main energy resource for generating ocean waves, which are the result of the interaction between wind and the ocean surface. While numerous methods to handle simulating oceans and other fluid phenomena have undergone rapid development during the past years in the field of computer graphic, few of them consider to construct ocean surface height field from the perspective of wind force driving ocean waves. We introduce wind force to the construction of the ocean surface height field through applying wind field data and wind-driven wave particles. Continual and realistic ocean waves result from the overlap of wind-driven wave particles, and a strategy was proposed to control these discrete wave particles and simulate an endless ocean surface. The results showed that the new method is capable of obtaining a realistic ocean scene under the influence of wind fields at real time rates.

  16. Ocean Wave Simulation Based on Wind Field

    Science.gov (United States)

    2016-01-01

    Ocean wave simulation has a wide range of applications in movies, video games and training systems. Wind force is the main energy resource for generating ocean waves, which are the result of the interaction between wind and the ocean surface. While numerous methods to handle simulating oceans and other fluid phenomena have undergone rapid development during the past years in the field of computer graphic, few of them consider to construct ocean surface height field from the perspective of wind force driving ocean waves. We introduce wind force to the construction of the ocean surface height field through applying wind field data and wind-driven wave particles. Continual and realistic ocean waves result from the overlap of wind-driven wave particles, and a strategy was proposed to control these discrete wave particles and simulate an endless ocean surface. The results showed that the new method is capable of obtaining a realistic ocean scene under the influence of wind fields at real time rates. PMID:26808718

  17. Wind power investment within a market environment

    International Nuclear Information System (INIS)

    Baringo, L.; Conejo, A.J.

    2011-01-01

    Highlights: → The interaction of a wind power investor and the pool is represented via an MPEC. → The considered electricity pool is cleared through a network constrained auction. → Uncertainty of load and wind production is characterized by a moderate number of scenarios. → The investment model can be recast as a mixed integer linear programming problem. → Large instances of the considered model are computationally tractable. - Abstract: Within an existing transmission network, this paper considers the problem of identifying the wind power plants to be built by a wind power investor to maximize its profit. For this analysis a future target year is considered and the loads at different buses are represented by stepwise load-duration curves. The stochastic nature of both load and wind is represented via scenarios. The considered electric energy system operates under a pool-market arrangement and each producer/consumer is paid/pays the Local Marginal Price (LMP) of the bus at which it is located. The higher the wind penetration is, the lower the resulting LMPs. To tackle this problem a stochastic bilevel model is proposed, whose upper-level represents the wind investment and operation decisions with the target of maximizing profits; and its lower-level represents the market clearing under differing load and wind conditions and provides LMPs. This model can be recast as a mixed-integer linear programming problem solvable using commercially available branch-and-cut solvers. The proposed model is illustrated using an example and two case studies.

  18. Analysing wind farm efficiency on complex terrains

    International Nuclear Information System (INIS)

    Castellani, Francesco; Astolfi, Davide; Terzi, Ludovico; Hansen, Kurt Schaldemose; Rodrigo, Javier Sanz

    2014-01-01

    Actual performances of onshore wind farms are deeply affected both by wake interactions and terrain complexity: therefore monitoring how the efficiency varies with the wind direction is a crucial task. Polar efficiency plot is therefore a useful tool for monitoring wind farm performances. The approach deserves careful discussion for onshore wind farms, where orography and layout commonly affect performance assessment. The present work deals with three modern wind farms, owned by Sorgenia Green, located on hilly terrains with slopes from gentle to rough. Further, onshore wind farm of Nprrekffir Enge has been analysed as a reference case: its layout is similar to offshore wind farms and the efficiency is mainly driven by wakes. It is shown and justified that terrain complexity imposes a novel and more consistent way for defining polar efficiency. Dependency of efficiency on wind direction, farm layout and orography is analysed and discussed. Effects of atmospheric stability have been also investigated through MERRA reanalysis data from NASA satellites. Monin-Obukhov Length has been used to discriminate climate regimes

  19. Better integration of wind power. Analysis of Danish legislation on tariffs, taxes and other significant conditions. Summary report and 3 appendix reports.; Denmark; Bedre integration af vind. Analyse af elpatronloven, treledstariffen for mindre kraftvarmeanlaeg, afgifter og andre vaesentlige rammebetingelser. Sammenfatning samt 3 bilagsrapporter

    Energy Technology Data Exchange (ETDEWEB)

    Togeby, M.; Werling, J.; Hethey, J. (and others)

    2009-06-15

    For the Danish Energy Agency and the Danish Ministry of Taxation, Ea Energianalyse and Risoe DTU have analysed how wind power can be better integrated into Danish the energy system so that economic and environmental impact of wind power improves. As a particular task, it is assessed whether the pilot scheme of reduced tariffs for electricity for heat and the payment for electricity for small cogeneration plants are appropriate. A number of framework conditions and technical solutions are evaluated and prioritized as part of the general assessment of options for better integration of wind power in the Danish power system. Besides the synthesis report, the publication contains three sub reports, which provide an analysis of the issues on integration of wind power, an analysis of the various options, and an analysis of the socioeconomic consequences by changing the taxes and tariffs. (ln)

  20. Evolution of wind towards wind turbine

    NARCIS (Netherlands)

    Giyanani, A.H.; Bierbooms, W.A.A.M.; Van Bussel, G.J.W.

    2015-01-01

    Remote sensing of the atmospheric variables with the use of LiDAR is a relatively new technology field for wind resource assessment in wind energy. The validation of LiDAR measurements and comparisons is of high importance for further applications of the data.

  1. Why the Coriolis force turns a wind farm wake clockwise in the Northern Hemisphere

    DEFF Research Database (Denmark)

    van der Laan, Paul; Sørensen, Niels N.

    2017-01-01

    and a roughness change. When the wind farm simulations are performed with a horizontally constant Coriolis force in order to isolate the effect of the wind veer, the wind farm wake deflection of the 5 × 5 actuator disks simulation remains unchanged. This proves that the present wind veer deflects the wind farm......The interaction between the Coriolis force and a wind farm wake is investigated by Reynoldsaveraged Navier–Stokes simulations, using two different wind farm representations: a high roughness and 5 × 5 actuator disks. Surprisingly, the calculated wind farm wake deflection is the opposite in the two...... simulations. A momentum balance in the cross flow direction shows that the interaction between the Coriolis force and the 5 × 5 actuator disks is complex due to turbulent mixing of veered momentum from above into the wind farm, which is not observed for the interaction between the Coriolis force...

  2. Wind Tunnel Measurements at LM Wind Power

    DEFF Research Database (Denmark)

    Bertagnolio, Franck

    2012-01-01

    The optimization of airfoil profiles specifically designed for wind turbine application was initiated in the late 80’s [67, 68, 30, 15]. The first attempts to reduce airfoil noise for wind turbines made use of airfoil trailing edge serration. Themodification of airfoil shapes targeted at noise...... reduction is more recent. An important effort was produced in this direction within the SIROCCO project. This latter work involved measurements on full size wind turbines and showed that trailing edge serration may proved a viable solution for mitigating wind turbine noise though it has not been implemented...... on commercial wind turbine yet. It should be mentioned here that the attenuation of turbulent inflow noise using wavy leading edge has recently been investigated [55], but this technique has still to be further validated for practical applications. In this paper, it is proposed to optimize an airfoil which...

  3. The immunology of the vermiform appendix: a review of the literature

    NARCIS (Netherlands)

    Kooij, I. A.; Sahami, S.; Meijer, S. L.; Buskens, C. J.; te Velde, A. A.

    2016-01-01

    This literature review assesses the current knowledge about the immunological aspects of the vermiform appendix in health and disease. An essential part of its immunological function is the interaction with the intestinal bacteria, a trait shown to be preserved during its evolution. The existence of

  4. An evaluation of the WindEye wind lidar

    DEFF Research Database (Denmark)

    Dellwik, Ebba; Sjöholm, Mikael; Mann, Jakob

    Prevision of the wind field by remote sensing wind lidars has the potential to improve the performance of wind turbines. The functionality of a WindEye lidar developed by Windar Photonics A/S (Denmark) for the wind energy market was tested in a two months long field experiment. The WindEye sensor...... with a high accuracy during the whole campaign....

  5. Wind electric power generation

    International Nuclear Information System (INIS)

    Koch, M.K.; Wind, L.; Canter, B.; Moeller, T.

    2001-01-01

    The monthly statistics of wind electric power generation in Denmark are compiled from information given by the owners of the private wind turbines. For each wind turbine the name of the site and of the type of turbine is given, and the power generation data are given for the month in question together with the total production in 1999 and 2000. Also the data of operation start are given. On the map of Denmark the sites of the wind turbines are marked. (CLS)

  6. The Irish Wind Atlas

    Energy Technology Data Exchange (ETDEWEB)

    Watson, R. [Univ. College Dublin, Dept. of Electronic and Electrical Engineering, Dublin (Ireland); Landberg, L. [Risoe National Lab., Meteorology and Wind Energy Dept., Roskilde (Denmark)

    1999-03-01

    The development work on the Irish Wind Atlas is nearing completion. The Irish Wind Atlas is an updated improved version of the Irish section of the European Wind Atlas. A map of the irish wind resource based on a WA{sup s}P analysis of the measured data and station description of 27 measuring stations is presented. The results of previously presented WA{sup s}P/KAMM runs show good agreement with these results. (au)

  7. 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....

  8. Wind Power Now!

    Science.gov (United States)

    Inglis, David Rittenhouse

    1975-01-01

    The government promotes and heavily subsidizes research in nuclear power plants. Federal development of wind power is slow in comparison even though much research with large wind-electric machines has already been conducted. Unless wind power programs are accelerated it will not become a major energy alternative to nuclear power. (MR)

  9. Power from the Wind

    Science.gov (United States)

    Roman, Harry T.

    2004-01-01

    Wind energy is the fastest-growing renewable energy source in the world. Over the last 20 years, the wind industry has done a very good job of engineering machines, improving materials, and economies of production, and making this energy source a reality. Like all renewable energy forms, wind energy's successful application is site specific. Also,…

  10. Extreme winds in Denmark

    DEFF Research Database (Denmark)

    Kristensen, L.; Rathmann, O.; Hansen, S.O.

    1999-01-01

    Wind-speed data from four sites in Denmark have been analyzed in order to obtain estimates of the basic wind velocity, defined as the 50-year wind speed (ten minute averages) under standard conditions, i.e. 10 meter over a homogeneous terrain with the roughness length 0.05 m. The sites are Skjern...

  11. Extreme winds in Denmark

    DEFF Research Database (Denmark)

    Kristensen, L.; Rathmann, Ole; Hansen, S.O.

    1999-01-01

    Wind-speed data from four sites in Denmark have been analyzed in order to obtain estimates of the basic wind velocity which is defined as the 50-year wind speed under standard conditions, i.e. ten-minute averages at the height 10 m over a uniform terrainwith the roughness length 0.05 m. The sites...

  12. Modelling Wind for Wind Farm Layout Optimization Using Joint Distribution of Wind Speed and Wind Direction

    DEFF Research Database (Denmark)

    Feng, Ju; Shen, Wen Zhong

    2015-01-01

    Reliable wind modelling is of crucial importance for wind farm development. The common practice of using sector-wise Weibull distributions has been found inappropriate for wind farm layout optimization. In this study, we propose a simple and easily implementable method to construct joint distribu......Reliable wind modelling is of crucial importance for wind farm development. The common practice of using sector-wise Weibull distributions has been found inappropriate for wind farm layout optimization. In this study, we propose a simple and easily implementable method to construct joint...... quite well in terms of the coefficient of determination R-2. Then, the best of these joint distributions is used in the layout optimization of the Horns Rev 1 wind farm and the choice of bin sizes for wind speed and wind direction is also investigated. It is found that the choice of bin size for wind...... direction is especially critical for layout optimization and the recommended choice of bin sizes for wind speed and wind direction is finally presented....

  13. Wind and Yaw correlation

    DEFF Research Database (Denmark)

    Federici, Paolo; Kock, Carsten Weber

    The report describes measurements carried out on a given turbine and period. The measurements are carried out in accordance to Ref. [1]. A comparison between wind speed and wind direction on the met mast and nacelle wind speed and yaw direction is made in accordance to Ref. [2] and the results...... are presented on graphs and in a table....

  14. Wind power soars

    Energy Technology Data Exchange (ETDEWEB)

    Flavin, C. [Worldwatch Inst., Washington, DC (United States)

    1996-12-31

    Opinions on the world market for wind power are presented in this paper. Some data for global wind power generating capacity are provided. European and other markets are discussed individually. Estimated potential for wind power is given for a number of countries. 3 figs.

  15. Wind power outlook 2006

    Energy Technology Data Exchange (ETDEWEB)

    anon.

    2006-04-15

    This annual brochure provides the American Wind Energy Association's up-to-date assessment of the wind industry in the United States. This 2006 general assessment shows positive signs of growth, use and acceptance of wind energy as a vital component of the U.S. energy mix.

  16. Wind and Yaw correlation

    DEFF Research Database (Denmark)

    Federici, Paolo; Kock, Carsten Weber

    The report describes measurements carried out on a given turbine and period. The measurements are carried out in accordance to Ref. [1]. A comparison between wind speed and wind direction on the met mast and nacelle wind speed and yaw direction is made in accordance to Ref. [2] and the results...

  17. Wind: French revolutions

    International Nuclear Information System (INIS)

    Jones, C.

    2006-01-01

    Despite having the second best wind resources in Europe after the UK, the wind industry in France lags behind its European counterparts with just 6 W of installed wind capacity per person. The electricity market in France is dominated by the state-owned Electricite de France (EdF) and its nuclear power stations. However, smaller renewable generators are now in theory allowed access to the market and France has transposed the EU renewables directive into national law. The French governement has set a target of generating 10,000 MW of renewable capacity by 2010. The announcement of an increased feed-in tariff and the introduction of 'development zones' (ZDEs) which could allow fast-tracking of planning for wind projects are also expected to boost wind projects. But grid access and adminstrative burdens remain major barriers. In addition, French politicians and local authorities remain committed to nuclear, though encouraged by the European Commission, wind is beginning to gain acceptance; some 325 wind farms (representing 1557 MW of capacity) were approved between February 2004 and January 2005. France is now regarded by the international wind energy sector as a target market. One of France's leading independent wind developers and its only listed wind company, Theolia, is expected to be one of the major beneficiaries of the acceleration of activity in France, though other companies are keen to maximise the opportunities for wind. France currently has only one indigenous manufacturer of wind turbines, but foreign suppliers are winning orders

  18. Denmark Wind Energy Programme

    DEFF Research Database (Denmark)

    Shen, Wen Zhong

    2015-01-01

    In this chapter, a summary of some ongoing wind energy projects in Denmark is given. The research topics comprise computational model development, wind turbine (WT) design, low-noise airfoil and blade design, control device development, wake modelling and wind farm layout optimization....

  19. Wind energy in Mediterranean Basin

    International Nuclear Information System (INIS)

    Gaudiosi, G.

    1991-01-01

    In its examination of wind energy potential in the Mediterranean Basin, this paper provides brief notes on the Basin's geography; indicates power production and demand; describes the area's wind characteristics and wind monitoring activities; illustrates wind velocity distributions; estimates local wind power production potential; reviews the Basin's wind energy marketing situation and each bordering country's wind energy programs; surveys installed wind energy farms; and assesses national research and commercialization efforts

  20. Wind and seismic analysis for liquid-level gauge support

    International Nuclear Information System (INIS)

    Ziada, A.H.

    1994-01-01

    A wind and seismic analysis was performed for the liquid-level gauge installation support stand. The analysis includes the stand and footing only. All of these supports are classified as safety class 3. The analysis was based on safety class 2 requirements for conservatism. Conventional hand calculations were performed to evaluate the stresses and overturning of the structure. The results and recommendations appear in Section 2.0. The configuration and loadings are discussed in Section 3.0; the analysis and evaluation appears in Section 4.0; and the detailed analysis is documented in Appendix A

  1. 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

  2. Offshore wind resource estimation for wind energy

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Badger, Merete; Mouche, A.

    2010-01-01

    Satellite remote sensing from active and passive microwave instruments is used to estimate the offshore wind resource in the Northern European Seas in the EU-Norsewind project. The satellite data include 8 years of Envisat ASAR, 10 years of QuikSCAT, and 23 years of SSM/I. The satellite observati......Satellite remote sensing from active and passive microwave instruments is used to estimate the offshore wind resource in the Northern European Seas in the EU-Norsewind project. The satellite data include 8 years of Envisat ASAR, 10 years of QuikSCAT, and 23 years of SSM/I. The satellite...... observations are compared to selected offshore meteorological masts in the Baltic Sea and North Sea. The overall aim of the Norsewind project is a state-of-the-art wind atlas at 100 m height. The satellite winds are all valid at 10 m above sea level. Extrapolation to higher heights is a challenge. Mesoscale...... modeling of the winds at hub height will be compared to data from wind lidars observing at 100 m above sea level. Plans are also to compare mesoscale model results and satellite-based estimates of the offshore wind resource....

  3. Potentials of wind power

    International Nuclear Information System (INIS)

    Bezrukikh, P.P.; Bezrukikh, P.P.

    2000-01-01

    The ecological advantages of the wind power facilities (WPF) are considered. The possibilities of small WPF, generating the capacity from 40 W up to 10 kW, are discussed. The basic technical data on the national and foreign small WPF are presented. The combined wind power systems are considered. Special attention is paid to the most perspective wind-diesel systems, which provide for all possible versions of the electro-power supply. Useful recommendations and information on the wind power engineering are given for those, who decided to build up a wind facility [ru

  4. Visualization of wind farms

    International Nuclear Information System (INIS)

    Pahlke, T.

    1994-01-01

    With the increasing number of wind energy installations the visual impact of single wind turbines or wind parks is a growing problem for landscape preservation, leading to resistance of local authorities and nearby residents against wind energy projects. To increase acceptance and to form a basis for planning considerations, it is necessary to develop instruments for the visualization of planned wind parks, showing their integration in the landscape. Photorealistic montages and computer animation including video sequences may be helpful in 'getting the picture'. (orig.)

  5. Mapping Wind Energy Controversies

    DEFF Research Database (Denmark)

    Munk, Anders Kristian

    As part the Wind2050 project funded by the Danish Council for Strategic Research we have mapped controversies on wind energy as they unfold online. Specifically we have collected two purpose built datasets, a web corpus containing information from 758 wind energy websites in 6 different countries......, and a smaller social media corpus containing information from 14 Danish wind energy pages on Facebook. These datasets have been analyzed to answer questions like: How do wind proponents and opponents organize online? Who are the central actors? And what are their matters of concern? The purpose of this report...

  6. Wind energy applications guide

    Energy Technology Data Exchange (ETDEWEB)

    anon.

    2001-01-01

    The brochure is an introduction to various wind power applications for locations with underdeveloped transmission systems, from remote water pumping to village electrification. It includes an introductory section on wind energy, including wind power basics and system components and then provides examples of applications, including water pumping, stand-alone systems for home and business, systems for community centers, schools, and health clinics, and examples in the industrial area. There is also a page of contacts, plus two specific example applications for a wind-diesel system for a remote station in Antarctica and one on wind-diesel village electrification in Russia.

  7. Wind energy systems

    International Nuclear Information System (INIS)

    Richardson, R.D.; McNerney, G.M.

    1993-01-01

    Wind energy has matured to a level of development where it is ready to become a generally accepted utility generation technology. A brief discussion of this development is presented, and the operating and design principles are discussed. Alternative designs for wind turbines and the tradeoffs that must be considered are briefly compared. Development of a wind energy system and the impacts on the utility network including frequency stability, voltage stability, and power quality are discussed. The assessment of wind power station economics and the key economic factors that determine the economic viability of a wind power plant are presented

  8. Mid-Atlantic Wind - Overcoming the Challenges

    Energy Technology Data Exchange (ETDEWEB)

    Daniel F. Ancona III; Kathryn E. George; Richard P. Bowers; Dr. Lynn Sparling; Bruce Buckheit; Daniel LoBue

    2012-05-31

    This study, supported by the US Department of Energy, Wind Powering America Program, Maryland Department of Natural Resources and Chesapeake Bay Foundation, analyzed barriers to wind energy development in the Mid-Atlantic region along with options for overcoming or mitigating them. The Mid-Atlantic States including Delaware, Maryland, North Carolina and Virginia, have excellent wind energy potential and growing demand for electricity, but only two utility-scale projects have been installed to date. Reasons for this apathetic development of wind resources were analyzed and quantified for four markets. Specific applications are: 1) Appalachian mountain ridgeline sites, 2) on coastal plains and peninsulas, 3) at shallow water sites in Delaware and Chesapeake Bays, Albemarle and Pamlico Sounds, and 4) at deeper water sites off the Atlantic coast. Each market has distinctly different opportunities and barriers. The primary barriers to wind development described in this report can be grouped into four categories; state policy and regulatory issues, wind resource technical uncertainty, economic viability, and public interest in environmental issues. The properties of these typologies are not mutually independent and do interact. The report concluded that there are no insurmountable barriers to land-based wind energy projects and they could be economically viable today. Likewise potential sites in sheltered shallow waters in regional bay and sounds have been largely overlooked but could be viable currently. Offshore ocean-based applications face higher costs and technical and wind resource uncertainties. The ongoing research and development program, revision of state incentive policies, additional wind measurement efforts, transmission system expansion, environmental baseline studies and outreach to private developers and stakeholders are needed to reduce barriers to wind energy development.

  9. Mid-Atlantic Wind - Overcoming the Challenges

    Energy Technology Data Exchange (ETDEWEB)

    Daniel F. Ancona III; Kathryn E. George; Lynn Sparling; Bruce C. Buckheit; Daniel LoBue; and Richard P. Bowers

    2012-06-29

    This study, supported by the US Department of Energy, Wind Powering America Program, Maryland Department of Natural Resources and Chesapeake Bay Foundation, analyzed barriers to wind energy development in the Mid-Atlantic region along with options for overcoming or mitigating them. The Mid-Atlantic States including Delaware, Maryland, North Carolina and Virginia, have excellent wind energy potential and growing demand for electricity, but only two utility-scale projects have been installed to date. Reasons for this apathetic development of wind resources were analyzed and quantified for four markets. Specific applications are: 1) Appalachian mountain ridgeline sites, 2) on coastal plains and peninsulas, 3) at shallow water sites in Delaware and Chesapeake Bays, Albemarle and Pamlico Sounds, and 4) at deeper water sites off the Atlantic coast. Each market has distinctly different opportunities and barriers. The primary barriers to wind development described in this report can be grouped into four categories; state policy and regulatory issues, wind resource technical uncertainty, economic viability, and public interest in environmental issues. The properties of these typologies are not mutually independent and do interact. The report concluded that there are no insurmountable barriers to land-based wind energy projects and they could be economically viable today. Likewise potential sites in sheltered shallow waters in regional bay and sounds have been largely overlooked but could be viable currently. Offshore ocean-based applications face higher costs and technical and wind resource uncertainties. The ongoing research and development program, revision of state incentive policies, additional wind measurement efforts, transmission system expansion, environmental baseline studies and outreach to private developers and stakeholders are needed to reduce barriers to wind energy development.

  10. Public acceptance of wind farm development: Developer practices and review of scientific literature

    DEFF Research Database (Denmark)

    Cronin, Tom; Ram, Bonnie; Gannon, Jim

    This report is the first deliverable of Work Package 3 of the Wind2050 project. The Wind2050 project is about the public perception of wind power in Denmark, its role in the planning and development of wind farms and, ultimately, the meaning it has for reaching the Danish government’s targets...... for wind power in 2050. Work Package 3 looks specifically at how private developers handle the public’s perception of wind power and what it means for their projects. This report firstly outlines the common stages found in wind farm development and then discusses what manner of interaction the developer...

  11. Wind Tunnel Measurements at LM Wind Power

    DEFF Research Database (Denmark)

    Bertagnolio, Franck

    2012-01-01

    This section presents the results obtained during the experimental campaign that was conducted in the wind tunnel at LM Wind Power in Lunderskov from August 16th to 26th, 2010. The goal of this study is to validate the so-called TNO trailing edge noise model through measurements of the boundary...... layer turbulence characteristics and the far-field noise generated by the acoustic scattering of the turbulent boundary layer vorticies as they convect past the trailing edge. This campaign was conducted with a NACA0015 airfoil section that was placed in the wind tunnel section. It is equipped with high...

  12. Wind energy in Europe

    International Nuclear Information System (INIS)

    Evans, L.C.

    1992-01-01

    Wind energy should be an important part of the energy supply mix, both at home and abroad, to provide cleaner air and a more stable fuel supply. Not only can wind energy contribute to solving complex global issues, it also can provide a large market for American technological leadership. Even though utilities are paying more attention to wind in a number of states, there are no plans for major installations of wind power plants in the United States. At the same time, European nations have developed aggressive wind energy development programs, including both ambitious research and development efforts and market incentives. Many countries recognize the importance of the clean energy provided by wind technology and are taking steps to promote their fledgling domestic industries. The emphasis on market incentives is starting to pay off. In 1991, European utilities and developers installed nearly twice as much wind capacity as Americans did. In 1992 the gap will be even greater. This article reviews aggressive incentives offered by European governments to boost their domestic wind industries at home and abroad in this almost $1 billion per year market. By offering substantial incentives - considerably more than the American Wind Energy Association (AWEA) is proposing - European nations are ensuring dramatic near-term wind energy development and are taking a major step toward dominating the international wind industry of the 21st century

  13. Kansas Wind Energy Consortium

    Energy Technology Data Exchange (ETDEWEB)

    Gruenbacher, Don [Kansas State Univ., Manhattan, KS (United States)

    2015-12-31

    This project addresses both fundamental and applied research problems that will help with problems defined by the DOE “20% Wind by 2030 Report”. In particular, this work focuses on increasing the capacity of small or community wind generation capabilities that would be operated in a distributed generation approach. A consortium (KWEC – Kansas Wind Energy Consortium) of researchers from Kansas State University and Wichita State University aims to dramatically increase the penetration of wind energy via distributed wind power generation. We believe distributed generation through wind power will play a critical role in the ability to reach and extend the renewable energy production targets set by the Department of Energy. KWEC aims to find technical and economic solutions to enable widespread implementation of distributed renewable energy resources that would apply to wind.

  14. Wind Turbine Technologies

    DEFF Research Database (Denmark)

    Hansen, Anca Daniela

    2017-01-01

    The wind turbine technology is a very complex technology involving multidisciplinary and broad technical disciplines such as aerodynamics, mechanics, structure dynamics, meteorology as well as electrical engineering addressing the generation, transmission, and integration of wind turbines...... into the power system. Wind turbine technology has matured over the years and become the most promising and reliable renewable energy technology today. It has moved very fast, since the early 1980s, from wind turbines of a few kilowatts to today’s multimegawatt-sized wind turbines [13]. Besides their size......, 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...

  15. Wind tower service lift

    Science.gov (United States)

    Oliphant, David; Quilter, Jared; Andersen, Todd; Conroy, Thomas

    2011-09-13

    An apparatus used for maintaining a wind tower structure wherein the wind tower structure may have a plurality of legs and may be configured to support a wind turbine above the ground in a better position to interface with winds. The lift structure may be configured for carrying objects and have a guide system and drive system for mechanically communicating with a primary cable, rail or other first elongate member attached to the wind tower structure. The drive system and guide system may transmit forces that move the lift relative to the cable and thereby relative to the wind tower structure. A control interface may be included for controlling the amount and direction of the power into the guide system and drive system thereby causing the guide system and drive system to move the lift relative to said first elongate member such that said lift moves relative to said wind tower structure.

  16. Turning to the wind

    Science.gov (United States)

    Sorensen, B.

    1981-10-01

    Consideration is given the economic and technological aspects of both free-stream (horizontal-axis) and cross-wind (vertical-axis) wind energy conversion systems, with attention to operational devices ranging in rotor diameter from 10 to 40 m and in output from 22 to 630 kW. After a historical survey of wind turbine design and applications development, the near-term technical feasibility and economic attractiveness of combined wind/fossil-fueled generator and wind/hydroelectric systems are assessed. Also presented are estimates of wind energy potential extraction in the U.S. and Denmark, the industrial requirements of large-scale implementation, energy storage possibilities such as pumped hydro and flywheels, and cost comparisons of electrical generation by large and small wind systems, coal-fired plants, and light-water fission reactors.

  17. Wind power takes over

    International Nuclear Information System (INIS)

    2002-01-01

    All over the industrialized world concentrated efforts are being made to make wind turbines cover some of the energy demand in the coming years. There is still a long way to go, however, towards a 'green revolution' as far as energy is concerned, for it is quite futile to use wind power for electric heating. The article deals with some of the advantages and disadvantages of developing wind power. In Norway, for instance, environmentalists fear that wind power plants along the coast may have serious consequences for the stocks of white-tailed eagle and golden eagle. An other factor that delays the large-scale application of wind power in Norway is the low price of electricity. Some experts, however, maintain that wind power may already compete with new hydroelectric power of intermediate cost. The investment costs are expected to go down with one third by 2020, when wind power may be the most competitive energy source to utilize

  18. Wind energy conversion system

    Science.gov (United States)

    Longrigg, Paul

    1987-01-01

    The wind energy conversion system includes a wind machine having a propeller connected to a generator of electric power, the propeller rotating the generator in response to force of an incident wind. The generator converts the power of the wind to electric power for use by an electric load. Circuitry for varying the duty factor of the generator output power is connected between the generator and the load to thereby alter a loading of the generator and the propeller by the electric load. Wind speed is sensed electro-optically to provide data of wind speed upwind of the propeller, to thereby permit tip speed ratio circuitry to operate the power control circuitry and thereby optimize the tip speed ratio by varying the loading of the propeller. Accordingly, the efficiency of the wind energy conversion system is maximized.

  19. Wind Speed Preview Measurement and Estimation for Feedforward Control of Wind Turbines

    Science.gov (United States)

    Simley, Eric J.

    Wind turbines typically rely on feedback controllers to maximize power capture in below-rated conditions and regulate rotor speed during above-rated operation. However, measurements of the approaching wind provided by Light Detection and Ranging (lidar) can be used as part of a preview-based, or feedforward, control system in order to improve rotor speed regulation and reduce structural loads. But the effectiveness of preview-based control depends on how accurately lidar can measure the wind that will interact with the turbine. In this thesis, lidar measurement error is determined using a statistical frequency-domain wind field model including wind evolution, or the change in turbulent wind speeds between the time they are measured and when they reach the turbine. Parameters of the National Renewable Energy Laboratory (NREL) 5-MW reference turbine model are used to determine measurement error for a hub-mounted circularly-scanning lidar scenario, based on commercially-available technology, designed to estimate rotor effective uniform and shear wind speed components. By combining the wind field model, lidar model, and turbine parameters, the optimal lidar scan radius and preview distance that yield the minimum mean square measurement error, as well as the resulting minimum achievable error, are found for a variety of wind conditions. With optimized scan scenarios, it is found that relatively low measurement error can be achieved, but the attainable measurement error largely depends on the wind conditions. In addition, the impact of the induction zone, the region upstream of the turbine where the approaching wind speeds are reduced, as well as turbine yaw error on measurement quality is analyzed. In order to minimize the mean square measurement error, an optimal measurement prefilter is employed, which depends on statistics of the correlation between the preview measurements and the wind that interacts with the turbine. However, because the wind speeds encountered by

  20. The Solar Wind and The Sun in the Past

    Science.gov (United States)

    Wood, Brian E.

    Exposure to the solar wind can have significant long term consequences for planetary atmospheres, especially for planets such as Mars that are not protected by global magnetospheres. Estimating the effects of solar wind exposure requires knowledge of the history of the solar wind. Much of what we know about the Sun's past behavior is based on inferences from observations of young solar-like stars. Stellar analogs of the weak solar wind cannot be detected directly, but the interaction regions between these winds and the interstellar medium have been detected and used to estimate wind properties. I here review these observations, with emphasis on what they suggest about the history of the solar wind.

  1. Mucinous adenocarcinona of the appendix

    Directory of Open Access Journals (Sweden)

    Milton Roberto Furst Crenitte

    2013-06-01

    Full Text Available Diagnosis of malignancy in the vermiform appendix is quite rare. The most common histological malignant neoplasia found in this tiny portion of the gastrointestinal tract is represented by the mucinous adenocarcinoma. This entity predominates in males around 50 years of age, and clinical presentation usually mimics or occurs along with an acute appendicitis. Early diagnosis is outside the rule since most cases at this stage are symptomless. The authors present the case of a 59-year-old female patient who looked for medical attention complaining of abdominal pain. Physical examination and laboratory workup were poor in diagnostic findings. The computed tomography images were compatible with the diagnosis of appendicitis and/or appendiceal neoplasia. The patient underwent a laparotomy and right hemicolectomy. The histological examination disclosed a moderately differentiated mucinous adenocarcinoma of the appendix stage T4a, N0, M0. The patient outcome was uneventful and was referred to an oncological center.

  2. Duplication of appendix: an accidental finding

    OpenAIRE

    Varshney, Manoranjan; Shahid, Mohammad; Maheshwari, Veena; Mubeen, Aysha; Gaur, Kavita

    2011-01-01

    Duplication of appendix is extremely rare anomaly. The reported incidence is 0.004–0.009%. In most of the cases the finding is accidental. Here the authors are presenting a case of type A duplex appendix in a 25-year male patient.

  3. Interval Appendicectomy and Management of Appendix Mass ...

    African Journals Online (AJOL)

    A wholly conservative management without interval appendicectomy was instituted for 13 patients diagnosed as having appendix mass between 1998 and 2002 in the University of Benin Teaching Hospital, Benin City, Nigeria. Within three days of admission, one patient developed clinical features of ruptured appendix and ...

  4. Necrotizing arteritis of the appendix

    OpenAIRE

    Ciudad Cavero, Adriana; Purón del Aguila, Ramón

    2014-01-01

    In the pathological study of prophylactically removed appendices or appendicular present clinical pictures , you may find lesions of necrotizing arteritis. In 1932 , Plaut (13 ) described for the first time , this appendix necrotizing lesion at the level of small arteries and arterioles , as a specific and focal manifestation. From then until now , several authors have presented their contribution in this regard, sometimes describing the injury, individual personality , and others , relating ...

  5. Second wind in the offshore wind industry

    International Nuclear Information System (INIS)

    Philippe, Edouard; Neyme, Eric; Deboos, Christophe; Villageois, Jean-Remy; Gouverneur, Philippe; Gerard, Bernard; Fournier, Eric; Petrus, Raymond; Lemarquis, David; Dener, Marc; Bivaud, Jean-Pierre; Lemaire, Etienne; Nielsen, Steffen; Lafon, Xavier; Lagandre, Pierre; Nadai, Alain; Pinot de Villechenon, Edouard; Westhues, Markus; Herpers, Frederick; Bisiaux, Christophe; Sperlich, Miriam; Bales, Vincent; Vandenbroeck, Jan; His, Stephane; Derrey, Thierry; Barakat, Georges; Dakyo, Brayima; Carme, Laurent; Petit, Frederic; Ytournel, Sophie; Westhues, Markus; Diller, Armin; Premont, Antoine de; Ruer, Jacques; Lanoe, Frederic; Declercq, Jan; Holmager, Morten; Fidelin, Daniel; Guillet, Jerome; Dudziak, Gregory; Lapierre, Anne; Couturier, Ludovic; Audineau, Jean-Pierre; Rouaix, Eric; De Roeck, Yann-Herve; Quesnel, Louis; Duguet, Benjamin

    2011-06-01

    After several keynote addresses, this publication contains contributions and Power Point presentations proposed during this conference on the development of offshore wind energy. The successive sessions addressed the following issues: the offshore mass production of electricity (examples of Denmark and Belgium, laying and protecting offshore cables), the space, economic and environmental planning (the Danish experience, the role of the Coastal area integrated management, importance of the public debate, so on), the logistics of port infrastructures (simulation tools, example of Bremerhaven, issues related to project management), innovation at the core of industrial strategies (high power wind turbines, the 6 MW Alstom turbine, chain value and innovation in offshore wind energy, the Vertiwing innovating project of a floating wind turbine, a bench test in Charleston, foundations, gravity base structures, the British experience, the Danish experience), the economic and organisational conditions for development, the validation and certification of technologies

  6. Small Signal Modeling of Wind Farms

    DEFF Research Database (Denmark)

    Ebrahimzadeh, Esmaeil; Blaabjerg, Frede; Wang, Xiongfei

    2017-01-01

    In large power electronic systems like a wind farm, the mutual interactions between the control systems of the power converters can lead to various stability and power quality problems. In order to predict the system dynamic behavior, this paper presents an approach to model a wind farm as a Multi......-Input Multi-Output (MIMO) dynamic system, where the current control loops with Phase-Locked Loops (PLLs) are linearized around an operating point. Each sub-module of the wind farm is modeled as a 2×2 admittance matrix in dq-domain and all are combined together by using a dq nodal admittance matrix....... The frequency and damping of the oscillatory modes are calculated by finding the poles of the introduced MIMO matrix. Time-domain simulation results obtained from a 400-MW wind farm are used to verify the effectiveness of the presented model....

  7. Optimum Operational Parameters for Yawed Wind Turbines

    Directory of Open Access Journals (Sweden)

    David A. Peters

    2011-01-01

    Full Text Available A set of systematical optimum operational parameters for wind turbines under various wind directions is derived by using combined momentum-energy and blade-element-energy concepts. The derivations are solved numerically by fixing some parameters at practical values. Then, the interactions between the produced power and the influential factors of it are generated in the figures. It is shown that the maximum power produced is strongly affected by the wind direction, the tip speed, the pitch angle of the rotor, and the drag coefficient, which are specifically indicated by figures. It also turns out that the maximum power can take place at two different optimum tip speeds in some cases. The equations derived herein can also be used in the modeling of tethered wind turbines which can keep aloft and deliver energy.

  8. Wind energy - Opinions of the ADEME

    International Nuclear Information System (INIS)

    2016-04-01

    This publication proposes brief presentations and discussions and some data related to the production of electricity by means of wind energy: principle and description, key data (international context, electric power production in France, economic development of the sector), status of knowledge regarding various aspects (assets of wind energy, a clean and local energy, a predictable and manageable source, an increasing competitiveness, a focus on offshore wind energy, control of acoustic and landscape impacts, protection of biodiversity, management of interactions with radars, a steady and clear regulation), perspectives of evolution (a sector of innovations, an opportunity for the development of circular economy, promotion of a participative and citizen wind energy), the case a small units, actions undertaken by the ADEME, and global opinion by the ADEME

  9. Observability of wind power

    International Nuclear Information System (INIS)

    Gonot, J.P.; Fraisse, J.L.

    2009-01-01

    The total installed capacity of wind power grows from a few hundred MW at the beginning of 2005 to 3400 MW at the end of 2008. With such a trend, a total capacity of 7000 MW could be reached by 2010. The natural variability of wind power and the difficulty of its predictability require a change in the traditional way of managing supply/demand balance, day-ahead margins and the control of electrical flows. As a consequence, RTE operators should be informed quickly and reliably of the real time output power of wind farms and of its evolvement some hours or days ahead to ensure the reliability of the French electrical power system. French specificities are that wind farms are largely spread over the territory, that 95 % of wind farms have an output power below 10 MW and that they are connected to the distribution network. In this context, new tools were necessary to acquire as soon as possible data concerning wind power. In two years long, RTE set up an observatory of wind production 'IPES system' enable to get an access to the technical characteristics of the whole wind farms, to observe in real time 75 % of the wind generation and to implement a forecast model related to wind generation. (authors)

  10. Financing wind projects

    International Nuclear Information System (INIS)

    Manson, J.

    2006-01-01

    This presentation reviewed some of the partnership opportunities available from GE Energy. GE Energy's ecomagination commitment has promised to double research investment, make customers true partners and reduce greenhouse gases (GHGs). GE Energy's renewable energy team provides a broad range of financial products, and has recently funded 30 wind farms and 2 large solar projects. The company has a diverse portfolio of technology providers and wind regimes, and is increasing their investment in technology. GE Energy recognizes that the wind industry is growing rapidly and has received increased regulatory support that is backed by strong policy and public support. It is expected that Canada will have 3006 wind projects either planned or under construction by 2007. According to GE Energy, successful wind financing is dependent on the location of the site and its wind resources, as well as on the wind developer's power sales agreement. The success of a wind project is also determined by clear financing goals. Site-specific data is needed to determine the quality of wind resource, and off-site data can also be used to provide validation. Proximity to load centres will help to minimize capital costs. Power sales agreements should be based on the project's realistic net capacity factor as well as on the cost of the turbines. The economics of many wind farms is driven by the size of the turbines used. Public consultations are also needed to ensure the success of wind power projects. It was concluded that a good partner will have staying power in the wind power industry, and will understand the time-lines and needs that are peculiar to wind energy developers. refs., tabs., figs

  11. Enhancement of wind stress evaluation method under storm conditions

    Science.gov (United States)

    Chen, Yingjian; Yu, Xiping

    2016-12-01

    Wind stress is an important driving force for many meteorological and oceanographical processes. However, most of the existing methods for evaluation of the wind stress, including various bulk formulas in terms of the wind speed at a given height and formulas relating the roughness height of the sea surface with wind conditions, predict an ever-increasing tendency of the wind stress coefficient as the wind speed increases, which is inconsistent with the field observations under storm conditions. The wave boundary layer model, which is based on the momentum and energy conservation, has the advantage to take into account the physical details of the air-sea interaction process, but is still invalid under storm conditions without a modification. By including the energy dissipation due to the presence of sea spray, which is speculated to be an important aspect of the air-sea interaction under storm conditions, the wave boundary layer model is improved in this study. The improved model is employed to estimate the wind stress caused by an idealized tropical cyclone motion. The computational results show that the wind stress coefficient reaches its maximal value at a wind speed of about 40 m/s and decreases as the wind speed further increases. This is in fairly good agreement with the field data.

  12. Vertical evolution of wind meandering in a nocturnal boundary layer during low-wind speed conditions

    Science.gov (United States)

    Stefanello, Michel; Acevedo, Otávio; Mortarini, Luca; Cava, Daniela; Giostra, Umberto; Degrazia, Gervásio; Anfossi, Domenico

    2017-04-01

    In the nocturnal boundary layer episodes of horizontal wind meandering are frequent. These episodes are characterised by low-wind regimes (wind speed less than 1.5 m s-1) in which submeso motions drive the wind dynamics and turbulence is weak and often intermittent. The inception of the meandering phenomenon as well as the interaction between turbulence and the submeso oscillations are still poorly understood. In this work we study the vertical evolution of the wind meandering by analysingnight-time anemometric data. The observations were carried on at a coastal site in Espirito Santo state, south-eastern Brazil from august to November 2016. The turbulent data, divided in hourly series, were collected in a 140-m tower designed to provide micrometeorological observations with high vertical resolution and deep coverage of the lower portion of the atmospheric boundary layer. Particularly, turbulence observations of the wind components and temperature are carried at 11 vertical levels. The tower has been deployed next to a natural gas power plant, at 3 km from the ocean. The terrain is generally flat for an area of 30 km from the tower, where moderate hills exist. The meandering timescale at each level is evaluated through the Eulerian Autocorrelation Functions of the horizontal wind velocity components and temperature, while the interactions between the different scales of motions is studied using the multi-correlation analysis. Thus the vertical evolution of meandering and time scales structure can be studied.

  13. Interaction of Accretion Shocks with Winds

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... Author Affiliations. Kinsuk Acharya1 Sandip K. Chakrabarti1 2 D. Molteni3. Centre for Space Physics, P-61 Southend Gardens, Kolkata 700 084, India. S. N. Bose National Center for Basic Sciences, JD Block, Salt Lake, Kolkata 700 098, India. University of Palermo, Via Archirafi 36, I-90123, Italy.

  14. Wind energy with special review on its usage in the Republic of Macedonia

    International Nuclear Information System (INIS)

    Arsenov, Arsen

    1996-01-01

    In this paper a short theoretical survey is given on the power limits that could be obtained as a result of the wind kinetic energy and on the development in the construction of different elements of eol power plants. A review is made on the different types of generator's losses. Multiple ways are shown for wind energy storage. Also, a review is given of the autonomic wind systems which are considered as especially attractive, as well as some examples for their realization. The wind energetic potential is analyzed for one location (Main Meteorological station - Stip), and the results from the calculations are given in a graphical form in the appendix. (author). 9 refs., 12 charts

  15. Dynamic responses of a wind turbine drivetrain under turbulent wind and voltage disturbance conditions

    Directory of Open Access Journals (Sweden)

    Chengwu Li

    2016-05-01

    Full Text Available Wind energy is known as one of the most efficient clean renewable energy sources and has attracted extensive research interests in both academic and industry fields. In this study, the effects of turbulent wind and voltage disturbance on a wind turbine drivetrain are analyzed, and a wind turbine drivetrain dynamic model combined with the electric model of a doubly fed induction generator is established. The proposed model is able to account for the dynamic interaction between turbulent wind, voltage disturbance, and mechanical system. Also, the effects of time-varying meshing stiffness, transmission error, and bearing stiffness are included in the mechanical part of the coupled dynamic model. From the resultant model, system modes are computed. In addition, by considering the actual control strategies in the simulation process, the effects of turbulent wind and voltage disturbance on the geared rotor system are analyzed. The computational results show that the turbulent wind and voltage disturbance can cause adverse effects on the wind turbine drivetrain, especially the gearbox. A series of parametric studies are also performed to understand the influences of generator and gearbox parameters on the drivetrain system dynamics. Finally, the appropriate generator parameters having a positive effect on the gearbox in alleviating the extreme loads and the modeling approach for investigating the transient performance of generator are discussed.

  16. TOPFARM - next generation design tool for optimisation of wind farm topology and operation

    DEFF Research Database (Denmark)

    Larsen, Gunner Chr.; Aagaard Madsen, Helge; Troldborg, Niels

    The present report is the publishable final activity report for the EU project TOPFARM. The project has been running from 1st December 2007 to 30th November 2010, and has successfully addressed optimization of wind farm topology and control strategy based on aero-elastic modeling of loads as well...... as of power production as seen in an economical perspective. Crucial factors in this regard are the overall wind climate at the wind farm site, the position of the individual wind turbines, the wind turbine characteristics, the internal wind farm wind climate, the wind turbine control/operation strategy...... for wind turbines interacting through wakes, various cost models, the optimization strategy and a priori defined constraints imposed on the wind farm topology. In TOPFARM, the object function used in the optimization platform is formulated in economical terms, thus ensuring the optimal balance between...

  17. Offshore Wind Power Data

    DEFF Research Database (Denmark)

    Cutululis, Nicolaos Antonio; Litong-Palima, Marisciel; Zeni, Lorenzo

    2012-01-01

    Wind power development scenarios are critical when trying to assess the impact of the demonstration at national and European level. The work described in this report had several objectives. The main objective was to prepare and deliver the proper input necessary for assessing the impact of Demo 4...... – Storm management at national and European level. For that, detailed scenarios for offshore wind power development by 2020 and 2030 were required. The aggregation level that is suitable for the analysis to be done is at wind farm level. Therefore, the scenarios for offshore wind power development offer...... details about the wind farms such as: capacity and coordinates. Since the focus is on the impact of storm fronts passage in Northen Europe, the offshore wind power scenarios were estimated only for the countries at North and Baltic Sea. The sources used are public sources, mentioned in the reference list...

  18. Wind farm economics

    International Nuclear Information System (INIS)

    Milborrow, D.J.

    1995-01-01

    The economics of wind energy are changing rapidly, with improvements in machine performance and increases in size both contributing to reduce costs. These trends are examined and future costs assessed. Although the United Kingdom has regions of high wind speed, these are often in difficult terrain and construction costs are often higher than elsewhere in Europe. Nevertheless, wind energy costs are converging with those of the conventional thermal sources. At present, bank loan periods for wind projects are shorter than for thermal plant, which means that energy prices are higher. Ways of overcoming this problem are explored. It is important, also, to examine the value of wind energy. It is argued that wind energy has a higher value than energy from centralized plant, since it is fed into the low-voltage distribution network. (Author)

  19. Wind power in France

    International Nuclear Information System (INIS)

    Tuille, F.; Courtel, J.

    2015-01-01

    After 3 years of steady decreasing, wind power has resumed growth in 2014 in France and the preliminary figures of 2015 confirm this trend. About 1100 MW were installed in 2014 which was almost twice as much as it was installed the year before. This renaissance is mostly due to the implementation of Brottes' law that eases the installations of wind farms by suppressing the wind power development areas (that were interfering with regional wind power schemes) and by suppressing the minimum number of 5 turbines for any new wind farms. Another important incentive measure was the announcement in January 2015 of a new financial support scheme in replacement of the policy of guaranteed purchase price for the electricity produced. In 2014 the total wind power produced in mainland France reached 17 TW which represented 3.1% of the production of electricity. (A.C.)

  20. Extreme winds in Denmark

    DEFF Research Database (Denmark)

    Kristensen, L.; Rathmann, O.; Hansen, S.O.

    2000-01-01

    ), Kegnaes (7 yr), Sprogo (20 yr), and Tystofte (16 yr). The measured data are wind speed, wind direction, temperature and pressure. The wind records are cleaned for terrain effects by means of WASP (Mortensew ct al., Technical Report I-666 (EN), Riso National Laboratory, 1993. Vol. 2. User's Guide......): assuming geostrophic balance, all the wind-velocity data are transformed to friction velocity u(*) and direction at standard conditions by means of the geostrophic drag law for neutral stratification. The basic wind velocity in 30 degrees sectors are obtained through ranking of the largest values...... of the friction velocity pressure pu(*)(2)/2 taken once every two months. The main conclusion is that the basic wind velocity is significantly larger at the west coast of Jutland (25 +/- 1 m/s) than at any of the other sites (22 +/- 1 m/s). These results are in agreement with those obtained by Jensen and Franck...

  1. Wind turbine state estimation

    DEFF Research Database (Denmark)

    Knudsen, Torben

    2014-01-01

    the results using full-scale wind turbine data. The previously developed methods were based on extended Kalman filtering. This method has several drawback compared to unscented Kalman filtering which has therefore been developed. The unscented Kalman filter was first tested on linear and non-linear test cases......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...... which was successful. Then the estimation of a wind turbine state including dynamic inflow was tested on a simulated NREL 5MW turbine was performed. This worked perfectly with wind speeds from low to nominal wind speed as the output prediction errors where white. In high wind where the pitch actuator...

  2. 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)

  3. Wind turbine pitch optimization

    DEFF Research Database (Denmark)

    Biegel, Benjamin; Juelsgaard, Morten; Stoustrup, Jakob

    2011-01-01

    We consider a static wind model for a three-bladed, horizontal-axis, pitch-controlled wind turbine. When placed in a wind field, the turbine experiences several mechanical loads, which generate power but also create structural fatigue. We address the problem of finding blade pitch profiles......% compared to any constant pitch profile while sacrificing at most 7% of the maximum attainable output power. Using iterative learning, we show that very similar performance can be achieved by using only load measurements, with no knowledge of the wind field or wind turbine model....... for maximizing power production while simultaneously minimizing fatigue loads. In this paper, we show how this problem can be approximately solved using convex optimization. When there is full knowledge of the wind field, numerical simulations show that force and torque RMS variation can be reduced by over 96...

  4. SERI Wind Energy Program

    Energy Technology Data Exchange (ETDEWEB)

    Noun, R. J.

    1983-06-01

    The SERI Wind Energy Program manages the areas or innovative research, wind systems analysis, and environmental compatibility for the U.S. Department of Energy. Since 1978, SERI wind program staff have conducted in-house aerodynamic and engineering analyses of novel concepts for wind energy conversion and have managed over 20 subcontracts to determine technical feasibility; the most promising of these concepts is the passive blade cyclic pitch control project. In the area of systems analysis, the SERI program has analyzed the impact of intermittent generation on the reliability of electric utility systems using standard utility planning models. SERI has also conducted methodology assessments. Environmental issues related to television interference and acoustic noise from large wind turbines have been addressed. SERI has identified the causes, effects, and potential control of acoustic noise emissions from large wind turbines.

  5. Wind Energy Systems

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Ma, Ke

    2017-01-01

    Wind power now represents a major and growing source of renewable energy. Large wind turbines (with capacities of up to 6-8 MW) are widely installed in power distribution networks. Increasing numbers of onshore and offshore wind farms, acting as power plants, are connected directly to power...... transmission networks at the scale of hundreds of megawatts. As its level of grid penetration has begun to increase dramatically, wind power is starting to have a significant impact on the operation of the modern grid system. Advanced power electronics technologies are being introduced to improve...... the characteristics of the wind turbines, and make them more suitable for integration into the power grid. Meanwhile, there are some emerging challenges that still need to be addressed. This paper provides an overview and discusses some trends in the power electronics technologies used for wind power generation...

  6. Danish Wind Power

    DEFF Research Database (Denmark)

    Lund, Henrik; Hvelplund, Frede; Østergaard, Poul Alberg

    In a normal wind year, Danish wind turbines generate the equivalent of approx. 20 percent of the Danish electricity demand. This paper argues that only approx. 1 percent of the wind power production is exported. The rest is used to meet domestic Danish electricity demands. The cost of wind power......, a study made by the Danish think tank CEPOS claimed the opposite, i.e. that most of the Danish wind power has been exported in recent years. However, this claim is based on an incorrect interpretation of statistics and a lack of understanding of how the international electricity markets operate...... is paid solely by the electricity consumers and the net influence on consumer prices was as low as 1-3 percent on average in the period 2004-2008. In 2008, the net influence even decreased the average consumer price, although only slightly. In Denmark, 20 percent wind power is integrated by using both...

  7. 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....

  8. 77 FR 29633 - Alta Wind VII, LLC, Alta Wind IX, LLC, Alta Wind X, LLC, Alta Wind XI, LLC, Alta Wind XII, LLC...

    Science.gov (United States)

    2012-05-18

    ..., Alta Wind XIV, LLC, Alta Wind XV, LLC, Alta Windpower Development, LLC, TGP Development Company, LLC... XIII, LLC, Alta Wind XIV, LLC, Alta Wind XV, LLC, Alta Windpower Development, LLC, and TGP Development...

  9. Field measurement of wind pressure and wind-induced vibration of large-span spatial cable-truss system under strong wind or typhoon

    Directory of Open Access Journals (Sweden)

    ZHANG Zhihong

    2013-10-01

    Full Text Available In order to ensure wind-resistance safety of large-span pre-stressed flexible system in southeast coast area of China,and to prepare something for revising of current codes of practice or technical standards,the present paper conducts field measurement of wind pressure and wind-induced vibration of a practical and typical large-span spatial cable-truss system-lunar stadium in Yueqing city.Wind loading and wind effects on full-scale structure under strong wind or typhoon in real architectural environment can be obtained directly and effectively.Field measurement is the best way to investigate the wind loading property,wind effects,and wind-structure interactions of large-span flexible system.Measured data will be highly valuable for scientific research and practical design.On the other hand,it also provides the basis of wind-resistance safety design of this kind of tension structures.If any creative development,it would dramatically improve the research level of large-span pre-stressed flexible system in our country.

  10. Proceedings of National Avian-Wind Power Planning Meeting IV

    Energy Technology Data Exchange (ETDEWEB)

    NWCC Avian Subcommittee

    2001-05-01

    OAK-B135 The purpose of the fourth meeting was to (1) share research and update research conducted on avian wind interactions (2) identify questions and issues related to the research results, (3) develop conclusions about some avian/wind power issues, and (4) identify questions and issues for future avian research.

  11. Interpretation of nonlinearity in wind generated ocean surface waves

    Digital Repository Service at National Institute of Oceanography (India)

    Varkey, M.J.

    This study attempts to resolve a mix-up between a physical process and its mathematical interpretation in the context of wind waves on ocean surface. Wind generated wave systems, are conventionally interpreted as a result of interaction of a number...

  12. Enabling Wind Power Nationwide

    Energy Technology Data Exchange (ETDEWEB)

    Jose Zayas, Michael Derby, Patrick Gilman and Shreyas Ananthan,

    2015-05-01

    Leveraging this experience, the U.S. Department of Energy’s (DOE’s) Wind and Water Power Technologies Office has evaluated the potential for wind power to generate electricity in all 50 states. This report analyzes and quantifies the geographic expansion that could be enabled by accessing higher above ground heights for wind turbines and considers the means by which this new potential could be responsibly developed.

  13. Wind and Yaw correlation

    DEFF Research Database (Denmark)

    Kock, Carsten Weber; Vesth, Allan

    The report describes measurements carried out on a given wind turbine. A comparison between wind speed on the metmast and Nacelle Windspeed are made and the results are presented on graphs and in a table. The data used for the comparison are identical with the data used for the Risø-I-3246(EN......) power curve report. The measurements are carried out in accordance to Ref. [1] and the wind and yaw correlation is analyzed in accordance to Ref. [2]....

  14. Research Needs for Wind Resource Characterization

    Science.gov (United States)

    Schreck, S. J.; Lundquist, J. K.; Shaw, W. J.

    2008-12-01

    to 200 meters and encompassing spatial and temporal resolution ranges unique to wind energy. The Mesoscale Processes area deemed improved understanding of mesoscale and local flows crucial to providing enhanced model outputs for wind energy production forecasts and wind plant siting. Modeling approaches need to be developed to resolve spatial scales in the 100 to 1000 meter range, a notable gap in current capabilities. Validation of these models will require new instruments and observational strategies, including augmented analyses of existing measurements. In the Climate Effects area, research was recommended to understand historical trends in wind resource variability. This was considered a prerequisite for improved predictions of future wind climate and resources, which would enable reliable wind resource estimation for future planning. Participants also considered it important to characterize interactions between wind plants and climates through modeling and observations that suitably emphasize atmospheric boundary layer dynamics. High-penetration wind energy deployment represents a crucial and attainable U.S. strategic objective. Achieving the 20 percent wind scenario will require an unprecedented ability for characterizing large wind turbines arrayed in gigawatt wind plants and extracting elevated energy levels from the atmosphere. DOE national laboratories, with industry and academia, represents a formidable capability for attaining these objectives.

  15. Wind power prediction models

    Science.gov (United States)

    Levy, R.; Mcginness, H.

    1976-01-01

    Investigations were performed to predict the power available from the wind at the Goldstone, California, antenna site complex. The background for power prediction was derived from a statistical evaluation of available wind speed data records at this location and at nearby locations similarly situated within the Mojave desert. In addition to a model for power prediction over relatively long periods of time, an interim simulation model that produces sample wind speeds is described. The interim model furnishes uncorrelated sample speeds at hourly intervals that reproduce the statistical wind distribution at Goldstone. A stochastic simulation model to provide speed samples representative of both the statistical speed distributions and correlations is also discussed.

  16. Wind on the moors

    International Nuclear Information System (INIS)

    Martin, S.

    1992-01-01

    A local town councillor describes the setting up of a wind farm in the south Pennines which plans to sell electricity to the local electricity suppliers. The Coal Clough wind farm will generate sufficient electricity to meet the average demand of 7,500 households and will be managed by a consortium known as Wind Resources Limited linking the construction company and the utilities aiming to buy the electricity produced. While wind power offers many environmental advantages over other means of power generation, local opposition was strong on the basis of the noise produced and clearly visible structures in an area designated as being of outstanding natural beauty. (UK)

  17. 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

  18. Microsystem Aeromechanics Wind Tunnel

    Data.gov (United States)

    Federal Laboratory Consortium — The Microsystem Aeromechanics Wind Tunnel advances the study of fundamental flow physics relevant to micro air vehicle (MAV) flight and assesses vehicle performance...

  19. Winds of change

    International Nuclear Information System (INIS)

    Palmer, C.; Short, L.

    1998-01-01

    The British countryside is oversubscribed with multiple and often irreconcilable demands. The siting of wind turbines is but one facet of this situation. While the problems of these demands are widely recognised, there is little understanding or agreement on how to resolve them. The 1996 Future Landscape: New Partnerships was an attempt to address this challenge. The use of wind energy as a case study initiated a partnership between contemporary artists and the wind energy industry. It became clear that artists have an important role to play in creating new ways of seeing that will establish wind turbines as new icons for a sustainable future. (Author)

  20. Could wind replace nuclear?

    International Nuclear Information System (INIS)

    2017-01-01

    This article aims at assessing the situation produced by a total replacement of nuclear energy by wind energy, while facing consumption demand at any moment, notably in December. The authors indicate the evolution of the French energy mix during December 2016, and the evolution of the rate between wind energy production and the sum of nuclear and wind energy production during the same month, and then give briefly some elements regarding necessary investments in wind energy to wholly replace nuclear energy. According to them, such a replacement would be ruinous

  1. Climate Wind Power Resources

    Directory of Open Access Journals (Sweden)

    Nana M. Berdzenishvili

    2013-01-01

    Full Text Available Georgia as a whole is characterized by rather rich solar energy resources, which allows to construct alternative power stations in the close proximity to traditional power plants. In this case the use of solar energy is meant. Georgia is divided into 5 zones based on the assessment of wind power resources. The selection of these zones is based on the index of average annual wind speed in the examined area, V> 3 m / s and V> 5 m / s wind speed by the summing duration in the course of the year and V = 0. . . 2 m / s of passive wind by total and continuous duration of these indices per hour.

  2. Wind Energy Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Laurie, Carol

    2017-02-01

    This book takes readers inside the places where daily discoveries shape the next generation of wind power systems. Energy Department laboratory facilities span the United States and offer wind research capabilities to meet industry needs. The facilities described in this book make it possible for industry players to increase reliability, improve efficiency, and reduce the cost of wind energy -- one discovery at a time. Whether you require blade testing or resource characterization, grid integration or high-performance computing, Department of Energy laboratory facilities offer a variety of capabilities to meet your wind research needs.

  3. 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.

  4. Wind Power in Georgia

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2012-11-01

    Georgia has good wind power potential. Preliminary analyses show that the technical wind power potential in Georgia is good. Meteorological data shows that Georgia has four main areas in Georgia with annual average wind speeds of over 6 m/s and two main areas with 5-6 m/s at 80m. The most promising areas are the high mountain zone of the Great Caucasus, The Kura river valley, The South-Georgian highland and the Southern part of the Georgian Black Sea coast. Czech company Wind Energy Invest has recently signed a Memorandum of Understanding with Georgian authorities for development of the first wind farm in Georgia, a 50MW wind park in Paravani, Southern Georgia, to be completed in 2014. Annual generation is estimated to 170.00 GWh and the investment estimated to 101 million US$. Wind power is suited to balance hydropower in the Georgian electricity sector Electricity generation in Georgia is dominated by hydro power, constituting 88% of total generation in 2009. Limited storage capacity and significant spring and summer peaks in river flows result in an uneven annual generation profile and winter time shortages that are covered by three gas power plants. Wind power is a carbon-free energy source well suited to balance hydropower, as it is available (often strongest) in the winter and can be exported when there is a surplus. Another advantage with wind power is the lead time for the projects; the time from site selection to operation for a wind power park (approximately 2.5 years) is much shorter than for hydro power (often 6-8 years). There is no support system or scheme for renewable sources in Georgia, so wind power has to compete directly with other energy sources and is in most cases more expensive to build than hydro power. In a country and region with rapidly increasing energy demands, the factors described above nevertheless indicate that there is a commercial niche and a role to play for Georgian wind power. Skra: An example of a wind power development

  5. The Impact of Coastal Terrain on Offshore Wind and Implications for Wind Energy

    Science.gov (United States)

    Strobach, Edward Justin

    The development of offshore wind energy is moving forward as one of several options for carbon-free energy generation along the populous US east coast. Accurate assessments of the wind resource are essential and can significantly lower financing costs that have been a barrier to development. Wind resource assessment in the Mid-Atlantic region is challenging since there are no long-term measurements of winds across the rotor span. Features of the coastal and inland terrain, such as such as the Appalachian mountains and the Chesapeake Bay, are known to lead to complex mesoscale wind regimes onshore, including low-level jets (LLJs), downslope winds and sea breezes. Little is known, however, about whether or how the inland physiography impacts the winds offshore. This research is based on the first comprehensive set of offshore wind observations in the Maryland Wind Energy Area gathered during a UMBC measurement campaign. The presentation will include a case study of a strong nocturnal LLJ that persisted for several hours before undergoing a rapid breakdown and loss of energy to smaller scales. Measurements from an onshore wind profiler and radiosondes, together with North American Regional Analysis (NARR) and a high resolution Weather Research and Forecast (WRF) model simulation, are used to untangle the forcing mechanisms on synoptic, regional and local scales that led to the jet and its collapse. The results suggest that the evolution of LLJs were impacted by a downslope wind from the Appalachians that propagated offshore riding atop a shallow near-surface boundary layer across the coastal plain. Baroclinic forcing from low sea surface temperatures (SSTs) due to coastal upwelling is also discussed. Smaller scale details of the LLJ breakdown are analyzed using a wave/mean flow/turbulence interaction approach. The case study illustrates several characteristics of low-level winds offshore that are important for wind energy, including LLJs, strong wind shear, turbulence

  6. Exposition concerning small windmills. Appendix to the main report. Vol. 2

    International Nuclear Information System (INIS)

    1992-12-01

    The second appendix to the main report entitled ''Exposition Concerning Small Windmills'' contains a description of the search for literature on the subject, a survey of relevant properties and a calculation of the ''shadow'' effect of small windmills, demands on electrical technology placed on small windmills, a survey of participating institutions and consultants, descriptions of the way the project was carried out (divided into phases) and maps of developing countries with details of wind conditions and possibilities of obtaining loans from the World Bank. (AB)

  7. Duplex vermiform appendix: case report of a ruptured second appendix.

    Science.gov (United States)

    Travis, John R; Weppner, Justin L; Paugh, James C

    2008-09-01

    Although the finding of appendiceal duplication is uncommon, its misdiagnosis and mismanagement may yield poor clinical outcomes and serious medicolegal consequences. Laparoscopic surgical exploration was performed on a 17-year-old male patient with right lower quadrant pain and a history of a previous appendectomy. Inspection of the cecum revealed a second appendix, which was retrocecal, ruptured, and gangrenous. Appendiceal duplication should be considered in all cases of lower abdominal pain, and careful inspection of the cecum for appendiceal anomalies should be performed. The Cave-Wallbridge classification system will be presented to assist surgeons in diagnosing appendiceal duplications.

  8. Quantifying wind resource assessment and grid integration challenges for Delaware offshore wind power utilizing mesoscale modeling techniques

    Science.gov (United States)

    Brodie, Joseph F.

    Offshore wind in the United States continues to be a focused area of research as our society grapples with the Earth's changing climate and our ongoing and increasing demand for electricity. While the first offshore wind project in the U.S. is expected to be operational soon, much still remains to be done to help improve viability of offshore wind in additional locations. This dissertation discusses three studies conducted to improve the understanding of and expectations from developing wind energy in the Delaware Wind Energy Area off the Delaware coast. The first study examines the capabilities of the Weather Research and Forecasting (WRF) model to account for variations in wind farm array geometries in an idealized set-up of the model, and determines features of those array geometries that can positively influence the energy production of an offshore farm. The second study investigates the impacts that the misprediction of wind ramp events would have on the interaction of an offshore wind farm with the electricity grid, quantifying some of these impacts and discussing factors which contribute to grid instability. The third study combines the knowledge gained in the first two studies to evaluate potential wind farm array geometries in a regional study of the Delaware Wind Energy Area using WRF along with a selection of case study dates selected to examine the impacts of the synoptic variability of the region throughout the year. These studies demonstrate that careful consideration of the meteorology and climatology of a region when determining the layout of an offshore wind array can improve the power production of the farm, thereby improving wind farm viability. It is shown that using a mesoscale model that incorporates a wind farm parameterization can improve resource assessment by allowing the assessment to evaluate the wind farm's interactions with the weather and climate in the Delaware Wind Energy Area. Furthermore, it is shown that while certain synoptic

  9. Wind Power Today: (2002) Wind Energy Research Highlights

    Energy Technology Data Exchange (ETDEWEB)

    2003-05-01

    Wind Power Today is an annual publication that provides an overview of the wind research conducted under the U.S. Department of Energy's Wind and Hydropower Technologies Program. The purpose of Wind Power Today is to show how DOE supports wind turbine research and deployment in hopes of furthering the advancement of wind technologies that produce clean, low-cost, reliable energy. Content objectives include: educate readers about the advantages and potential for widespread deployment of wind energy; explain the program's objectives and goals; describe the program's accomplishments in research and application; examine the barriers to widespread deployment; describe the benefits of continued research and development; facilitate technology transfer; and attract cooperative wind energy projects with industry. This 2002 edition of Wind Power Today also includes discussions about wind industry growth in 2002, how DOE is taking advantage of low wind speed regions through advancing technology, and distributed applications for small wind turbines.

  10. Cometary X-rays : solar wind charge exchange in cometary atmospheres

    NARCIS (Netherlands)

    Bodewits, Dennis

    2007-01-01

    The interaction of the solar wind with the planets and the interstellar medium is of key importance for the evolution of our solar system. The interaction with Earth's atmosphere is best known for the northern light. In case of Mars, the interaction with the solar wind might have lead to the erosion

  11. Sensing the wind profile

    Energy Technology Data Exchange (ETDEWEB)

    Pena, A.

    2009-03-15

    This thesis consists of two parts. The first is a synopsis of the theoretical progress of the study that is based on a number of journal papers. The papers, which constitute the second part of the report, aim to analyze, measure, and model the wind prole in and beyond the surface layer by combining observations from cup anemometers with lidars. The lidar is necessary to extend the measurements on masts at the Horns Rev offshore wind farm and over at land at Hoevsoere, Denmark. Both sensing techniques show a high degree of agreement for wind speed measurements performed at either sites. The wind speed measurements are averaged for several stability conditions and compare well with the surface-layer wind profile. At Hoevsoere, it is sufficient to scale the wind speed with the surface friction velocity, whereas at Horns Rev a new scaling is added, due to the variant roughness length. This new scaling is coupled to wind prole models derived for flow over the sea and tested against the wind proles up to 160 m at Horns Rev. The models, which account for the boundary-layer height in stable conditions, show better agreement with the measurements than compared to the traditional theory. Mixing-length parameterizations for the neutral wind prole compare well with length-scale measurements up to 300 m at Hoevsoere and 950 m at Leipzig. The mixing-length-derived wind proles strongly deviate from the logarithmic wind prole, but agree better with the wind speed measurements. The length-scale measurements are compared to the length scale derived from a spectral analysis performed up to 160 m at Hoevsoere showing high agreement. Mixing-length parameterizations are corrected to account for stability and used to derive wind prole models. These compared better to wind speed measurements up to 300 m at Hoevsoere than the surface-layer wind prole. The boundary-layer height is derived in nearneutral and stable conditions based on turbulent momentum uxes only and in unstable conditions

  12. Center for Computational Wind Turbine Aerodynamics and Atmospheric Turbulence

    DEFF Research Database (Denmark)

    Sørensen, Jens Nørkær

    2014-01-01

    In order to design and operate a wind farm optimally it is necessary to know in detail how the wind behaves and interacts with the turbines in a farm. This not only requires knowledge about meteorology, turbulence and aerodynamics, but it also requires access to powerful computers and efficient...... software. Center for Computational Wind Turbine Aerodynamics and Atmospheric Turbulence was established in 2010 in order to create a world-leading cross-disciplinary flow center that covers all relevant disciplines within wind farm meteorology and aerodynamics....

  13. Wind energy - an overview

    International Nuclear Information System (INIS)

    Rangi, R.; Oprisan, M.

    1998-01-01

    The current status of wind technology developments in Canada and around the world was reviewed. Information regarding the level of wind turbine deployment was presented. It was shown that significant effort has been made on the national and international level to increase the capacity of this clean, non-polluting form of energy. Wind energy has become competitive with conventional sources of electricity due to lower cost, higher efficiency and improved reliability of generating equipment. The advantages and disadvantages of wind electricity generating systems and the economics and atmospheric emissions of the systems were described. At present, there is about 23 MW of wind energy generating capacity installed in Canada, but the potential is very large. It was suggested that wind energy could supply as much as 60 per cent of Canada's electricity needs if only one per cent of the land with 'good winds' were covered by wind turbines. Recently, the Canadian government has provided an accelerated capital cost allowance for certain types of renewable energies under the Income Tax Act, and the flow-through share financing legislation to include intangible expenses in certain renewable energy projects has been extended. Besides the support provided to the private sector through tax advantages, the Government also supports renewable energy development by purchasing 'green' energy for its own buildings across the country, and by funding a research and development program to identify and promote application of wind energy technologies, improve its cost effectiveness, and support Canadian wind energy industries with technology development to enhance their competitiveness at home and abroad. Details of the Wind Energy Program, operated by Natural Resources Canada, are described. 3 tabs., 5 figs

  14. Appendix - A small scale research review

    DEFF Research Database (Denmark)

    Larsen, Lea Lund

    A small scale research review This appendix provides an analysis of a small scale search for empirical studies regarding the efficacy of adult teacher training. The appendix is a part of a paper delivered at the ASEM conference, June 2009, Bergisch Gladbach, Germany. The paper tries to shed light...... training? This will be illustrated by describing a research design in progress at the National Centre of Competence Development, DK, regarding a program where teachers are taught Cooperative Learning as a pedagogical and didactical method. This appendix concerns the first question. In search for empiric results concerning: What do...

  15. Wind power integration : From individual wind turbine to wind park as a power plant

    NARCIS (Netherlands)

    Zhou, Y.

    2009-01-01

    As power capacities of single wind turbine, single wind park and total wind power installation are continuously increasing, the wind power begins to challenge the safety operation of the power system. This thesis focuses on the grid integration aspects such as the dynamic behaviours of wind power

  16. LES investigation of infinite staggered wind-turbine arrays

    International Nuclear Information System (INIS)

    Yang, Xiaolei; Sotiropoulos, Fotis

    2014-01-01

    The layouts of turbines affect the turbine wake interactions and thus the wind farm performance. The wake interactions in infinite staggered wind-turbine arrays are investigated and compared with infinite aligned turbine arrays in this paper. From the numerical results we identify three types of wake behaviours, which are significantly different from wakes in aligned wind-turbine arrays. For the first type, each turbine wake interferes with the pair of staggered downstream turbine wakes and the aligned downstream turbine. For the second type, each turbine wake interacts with the first two downstream turbine wakes but does not show significant interference with the second aligned downstream turbine. For the third type, each turbine wake recovers immediately after passing through the gap of the first two downstream turbines and has little interaction with the second downstream turbine wakes The extracted power density and power efficiency are also studied and compared with aligned wind-turbine arrays

  17. Ocean Mixed Layer Response to Gap Wind Scenarios

    National Research Council Canada - National Science Library

    Konstantinou, Nikolaos

    2006-01-01

    This study focuses on understanding the oceanic response to gap outflow and the air-sea interaction processes during the gap wind event between 26 and 28 February 2004 over the Gulf of Tehuantepec, Mexico. The U.S...

  18. Wind speed dynamical model in a wind farm

    DEFF Research Database (Denmark)

    Soleimanzadeh, Maryam; Wisniewski, Rafal

    2010-01-01

    , the dynamic model for wind flow will be established. The state space variables are determined based on a fine mesh defined for the farm. The end goal of this method is to assist the development of a dynamical model of a wind farm that can be engaged for better wind farm control strategies.......This paper presents a model for wind speed in a wind farm. The basic purpose of the paper is to calculate approximately the wind speed in the vicinity of each wind turbine in a farm. In this regard the governing equations of flow will be solved for the whole wind farm. In ideal circumstances...

  19. Galactic winds and the hubble sequence

    International Nuclear Information System (INIS)

    Bregman, J.N.

    1978-01-01

    The conditions for maintenance of supernova-driven galactic winds have been investigated to assess their role in the morphology of disk-bulge galaxies. A fluid mechanical model with gas and stars which includes galactic rotation has been used to investigate several classes of winds. It is found that many galaxies, once their initial gas is depleted, can maintain a wind throughout the entire galaxy, a conditon most easily satisfied by systems with a small bulge-to-disk ratio. If the ratio of supernova heating to total mass loss falls below a critical value that depends on galaxy type and mass, only a partial wind exterior to a critical surface can exist, with infall occurring at interior points. Galaxies in which only the bulge was depleted of gas may support a bulge wind that does not interact with the colder and denser gas in the disk.These results indicate that if SO galaxies are a transition class between elliptical and spiral galaxies, it is probably because early galactic winds, which may initially deplete a galaxy of gas, are more prevalent in SO than in spiral galaxies. However, if SO's form a parallel sequence with spirals, the initial gas-depletion mechanism must be independent of bulge-to-disk ratio. These results are not strongly influenced by altering the galactic mass model, including electron conduction in the flow equations, or adding massive halos

  20. Fixture for winding transformers

    Science.gov (United States)

    Mclyman, M. T.

    1980-01-01

    Bench-mounted fixture assists operator in winding toroid-shaped transformer cores. Toroid is rigidly held in place as wires are looped around. Arrangement frees both hands for rapid winding and untangling of wires that occurs when core is hand held.

  1. 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

  2. NORCOWE Reference Wind Farm

    DEFF Research Database (Denmark)

    Bak, Thomas; Graham, Angus

    2015-01-01

    Offshore wind farms are complex systems, influenced by both the environment (e.g. wind, waves, current and seabed) and the design characteristics of the equipment available for installation (e.g. turbine type, foundations, cabling and distance to shore). These aspects govern the capital and opera...

  3. MWR, Meteor Wind Radars

    Science.gov (United States)

    Roper, R. G.

    1984-01-01

    The requirements of a state of the art meteor wind radar, and acceptable comprises in the interests of economy, are detailed. Design consideration of some existing and proposed radars are discussed. The need for international cooperation in mesopause level wind measurement, such as that being fostered by the MAP GLOBMET (Global Meteor Observations System) project, is emphasized.

  4. Research on wind energy

    CSIR Research Space (South Africa)

    Szewczuk, S

    2012-10-01

    Full Text Available & underlying technologies Ovid: composite man- rated trainer airplane Eskom?s wind farm, Klipheuwel, Cape Town ? CSIR, then DME & City of Cape Town undertook study on large grid connected wind turbines ? included a study tour to Europe. ? Recommended...

  5. Emerging wind energy technologies

    DEFF Research Database (Denmark)

    Rasmussen, Flemming; Grivel, Jean-Claude; Faber, Michael Havbro

    2014-01-01

    This chapter will discuss emerging technologies that are expected to continue the development of the wind sector to embrace new markets and to become even more competitive.......This chapter will discuss emerging technologies that are expected to continue the development of the wind sector to embrace new markets and to become even more competitive....

  6. 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...

  7. 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...

  8. The difficult wind power

    International Nuclear Information System (INIS)

    Groenaas, Sigbjoern

    2005-01-01

    The article presents a brief survey of the conditions for wind power production in Norway and points out that several areas should be well suited. A comparison to Danish climate is made. The wind variations, turbulence problems and regional conditions are discussed

  9. Wind Energy Systems.

    Science.gov (United States)

    Conservation and Renewable Energy Inquiry and Referral Service (DOE), Silver Spring, MD.

    During the 1920s and 1930s, millions of wind energy systems were used on farms and other locations far from utility lines. However, with passage of the Rural Electrification Act in 1939, cheap electricity was brought to rural areas. After that, the use of wind machines dramatically declined. Recently, the rapid rise in fuel prices has led to a…

  10. Measurement of global oceanic winds from Seasat-SMMR and its comparison with Seasat-SASS and ALT derived winds

    Science.gov (United States)

    Pandey, Prem C.

    1987-01-01

    The retrieval of ocean-surface wind speed from different channel combinations of Seasat SMMR measurements is demonstrated. Wind speeds derived using the best two channel subsets (10.6 H and 18.0 V) were compared with in situ data collected during the Joint Air-Sea Interaction (JASIN) experiment and an rms difference of 1.5 m/s was found. Global maps of wind speed generated with the present algorithm show that the averaged winds are arranged in well-ordered belts.

  11. Fort Carson Wind Resource Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Robichaud, R.

    2012-10-01

    This report focuses on the wind resource assessment, the estimated energy production of wind turbines, and economic potential of a wind turbine project on a ridge in the southeastern portion of the Fort Carson Army base.

  12. Proceedings of the CanWEA 2008 wind energy project siting seminar

    International Nuclear Information System (INIS)

    2008-01-01

    The conference provided a forum for members of the wind power industry and government agencies to discuss issues related to the siting of wind energy projects. Case studies were used to demonstrated various methods of negotiating with environmental and social considerations during the wind siting process. The visual impacts of wind energy projects were reviewed, and key issues for the assessment of bird-wind farm interactions in Canada were discussed. Recent bird and bat monitoring studies were outlined along with a review of national and international research related to bat-wind farm interactions. Regulations related to sound and windfarms were also outlined. The conference was divided into the following 8 sessions: (1) environmental and social considerations in wind energy project siting; (2) visual impacts and wind energy project siting; (3) birds and wind energy project siting; (4) bats and wind energy project siting; (5) sound and wind energy project siting; (6) radar-telecommunications issues and wind energy project siting; (7) regional issues and wind energy project siting; and (8) cumulative impacts and wind energy project siting. The conference featured 24 presentations, of which 19 have been catalogued separately for inclusion in this database. tabs., figs

  13. Study of wind forces on low-rise hip-roof building

    African Journals Online (AJOL)

    DR OKE

    Wind pressures on buildings and structures depend upon the velocity profile and turbulence ... the interaction between wind and structures numerically offering an alternative technique to practical applications. Earlier the ..... Areas of research are masonry structures, Computational Fluid Dynamics and Wind engineering.

  14. Assessment and prediction of wind turbine noise

    International Nuclear Information System (INIS)

    Lowson, M.V.

    1993-01-01

    The significance of basic aerodynamic noise sources for wind turbine noise are assessed, using information on the aero-acoustic mechanisms of other rotors, which have been studied in depth for many years. From the analysis, areas of potential improvement in wind turbine noise prediction are defined. Suggestions are made for approaches to wind turbine noise control which separate the noise problems at cut-in from those at rated power. Some of these offer the possibility of noise reduction without unfavourable effects on performance. Based on this analysis, a new model for prediction of wind turbine noise is presented and comparisons made between prediction and experiment. The model is based on well established aeroacoustic theory and published laboratory data for the two principal sources, inflow turbulence and boundary layer trailing edge interaction. The new method gives good agreement with experiment with the case studied so far. Parametric trends and sensitivities for the model are presented. Comparisons with previous prediction methods are also given. A consequence of the new model is to put more emphasis on boundary layer trailing edge interaction as a noise source. There are prospects for reducing noise from this source detail changes to the wind turbine design. (author)

  15. Offshore Wind Power

    DEFF Research Database (Denmark)

    Negra, Nicola Barberis

    The aim of the project is to investigate the influence of wind farms on the reliability of power systems. This task is particularly important for large offshore wind farms, because failure of a large wind farm might have significant influence on the balance of the power system, and because offshore...... Carlo simulation is used for these calculations: this method, in spite of an extended computation time, has shown flexibility in performing reliability studies, especially in case of wind generation, and a broad range of results which can be evaluated. The modelling is then extended to the entire power...... system considering conventional power plants, distributed generation based on wind energy and CHP technology as well as the load and transmission facilities. In particular, the different models are used to represent two well-known test systems, the RBTS and the IEEE-RTS, and to calculate...

  16. Urban Wind Energy

    DEFF Research Database (Denmark)

    Beller, Christina

    for the installation of wind turbines in cities, with Copenhagen, DK, as example. Focus is taken on turbine with a swept area of maximum 5m2, since turbines of this size are relatively easy to be integrated in the urban space and are in the financial range for small companies as well as for private persons. Elements......New trends e.g. in architecture and urban planning are to reduce energy needs. Several technologies are employed to achieve this, and one of the technologies, not new as such, is wind energy. Wind turbines are installed in cities, both by companies and private persons on both old and new buildings...... the lower wind energy in cities other factors foster the attractiveness of urban wind energy application, like the demand or wish to reduce CO2 emissions and the possibility to produce energy directly to ones household....

  17. Illinois Wind Workers Group

    Energy Technology Data Exchange (ETDEWEB)

    David G. Loomis

    2012-05-28

    The Illinois Wind Working Group (IWWG) was founded in 2006 with about 15 members. It has grown to over 200 members today representing all aspects of the wind industry across the State of Illinois. In 2008, the IWWG developed a strategic plan to give direction to the group and its activities. The strategic plan identifies ways to address critical market barriers to the further penetration of wind. The key to addressing these market barriers is public education and outreach. Since Illinois has a restructured electricity market, utilities no longer have a strong control over the addition of new capacity within the state. Instead, market acceptance depends on willing landowners to lease land and willing county officials to site wind farms. Many times these groups are uninformed about the benefits of wind energy and unfamiliar with the process. Therefore, many of the project objectives focus on conferences, forum, databases and research that will allow these stakeholders to make well-educated decisions.

  18. 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...

  19. Rule - based Fault Diagnosis Expert System for Wind Turbine

    Directory of Open Access Journals (Sweden)

    Deng Xiao-Wen

    2017-01-01

    Full Text Available Under the trend of increasing installed capacity of wind power, the intelligent fault diagnosis of wind turbine is of great significance to the safe and efficient operation of wind farms. Based on the knowledge of fault diagnosis of wind turbines, this paper builds expert system diagnostic knowledge base by using confidence production rules and expert system self-learning method. In Visual Studio 2013 platform, C # language is selected and ADO.NET technology is used to access the database. Development of Fault Diagnosis Expert System for Wind Turbine. The purpose of this paper is to realize on-line diagnosis of wind turbine fault through human-computer interaction, and to improve the diagnostic capability of the system through the continuous improvement of the knowledge base.

  20. Mammalian mesocarnivore visitation at tortoise burrows in a wind farm

    Science.gov (United States)

    Agha, Mickey; Smith, Amanda L.; Lovich, Jeffrey E.; Delaney, David F.; Ennen, Joshua R.; Briggs, Jessica R.; Fleckenstein, Leo J.; Tennant, Laura A.; Puffer, Shellie R.; Walde, Andrew D.; Arundel, Terry; Price, Steven J.; Todd, Brian D.

    2017-01-01

    There is little information on predator–prey interactions in wind energy landscapes in North America, especially among terrestrial vertebrates. Here, we evaluated how proximity to roads and wind turbines affect mesocarnivore visitation with desert tortoises (Gopherus agassizii) and their burrows in a wind energy landscape. In 2013, we placed motion-sensor cameras facing the entrances of 46 active desert tortoise burrows in a 5.2-km2 wind energy facility near Palm Springs, California, USA. Cameras recorded images of 35 species of reptiles, mammals, and birds. Counts for 4 species of mesocarnivores at desert tortoise burrows increased closer to dirt roads, and decreased closer to wind turbines. Our results suggest that anthropogenic infrastructure associated with wind energy facilities could influence the general behavior of mammalian predators and their prey. Further investigation of proximate mechanisms that underlie road and wind turbine effects (i.e., ground vibrations, sound emission, and traffic volume) and on wind energy facility spatial designs (i.e., road and wind turbine configuration) could prove useful for better understanding wildlife responses to wind energy development. © 2017 The Wildlife Society.

  1. European Wind Atlas and Wind Resource Research in Denmark

    DEFF Research Database (Denmark)

    Mortensen, Niels Gylling

    to estimate the actual wind climate at any specific site and height within this region. The Danish and European Wind Atlases are examples of how the wind atlas methodology can be employed to estimate the wind resource potential for a country or a sub-continent. Recently, the methodology has also been used...... - from wind measurements at prospective sites to wind tunnel simulations and advanced flow modelling. Among these approaches, the wind atlas methodology - developed at Ris0 National Laboratory over the last 25 years - has gained widespread recognition and is presently considered by many as the industry......-standard tool for wind resource assessment and siting of wind turbines. The PC-implementation of the methodology, the Wind Atlas Analysis and Application Program (WAsP), has been applied in more than 70 countries and territories world-wide. The wind atlas methodology is based on physical descriptions and models...

  2. Considering wind energy in regional planning guidelines and communal land-use planning; Die Beruecksichtigung der Windenergie in der Richt- und Nutzungsplanung

    Energy Technology Data Exchange (ETDEWEB)

    Soguel, R. [Atelier North and Robyr, Neuchatel (Switzerland); Henz, H.R. [Metron Raumplanung AG, Brugg (Switzerland)

    2001-07-01

    This report made for the Swiss Federal Office of Energy (SFOE) discusses the situation in Switzerland regarding the planning guidelines required at regional and communal level that are required for the granting of permission to build wind energy installations. Various types of wind turbines and wind farms are described and topics such as planning tools, landscape protection and promotional concepts are discussed. The role of the Swiss Cantons in the promotion of wind energy is examined and the question of how to integrate wind energy plant into cantonal and communal planning guidelines is looked at. This working guide introduces two schemes that demonstrate how the planning process for the construction of wind farms can be co-ordinated with the development of land-use plans. Examples of current cantonal guidelines are presented in the appendix to the report.

  3. Villous adenoma of the distal appendix.

    Science.gov (United States)

    Taylor, J V; Thomas, M G; Kelly, S; Sutton, R

    1997-04-01

    Villous adenoma confined to the distal appendix has not been previously reported in conjunction with acute apendicitis. The presence of an adenoma indicates a need for further investigation due to an association with neoplasia elsewhere.

  4. The vermiform appendix: not a useless organ.

    Science.gov (United States)

    Zahid, Aliya

    2004-04-01

    The appendix has often been seen more as a nuisance rather than an important part of the human anatomy. Early misconceptions have led to the indiscriminate removal of the appendix from the body. Long thought to be an evolutionary remnant of little significance to normal physiology, the appendix has more recently been identified as an important component of mammalian mucosal immune function, particularly B-lymphocyte-mediated immune responses and extrathymically derived T-lymphocytes. This structure helps in the proper movement and removal of waste matter in the digestive system, contains lymphatic vessels that regulate pathogens, and lastly, might even produce early defences that prevent deadly diseases. The appendix is one of the guardians of the internal environment of the body from the hostile external environment.

  5. On the difference between the magnetic intermittent micro-structures in fast wind and slow wind and it's implication for the solar wind turbulence cascade

    Science.gov (United States)

    Tu, C.; Wang, X.; He, J.; Marsch, E.; Wang, L.

    2013-12-01

    The magnetic intermittent micro-structures (on time scales of 20-40s) in both fast and slow solar wind are studied by using plasma and field measurements from the WIND spacecraft. In the fast wind these structures are found to be composed of mostly rotational discontinuities (RDs) and rarely tangential current sheets (TCSs). The RDs do not show prominent plasma-parameter changes. Conversely, the TCSs have a distinct tendency to be associated with local enhancements of the proton temperature, density, and plasma beta, and a local decrease of the magnetic field magnitude. These results show that dissipation of solar wind turbulence can take place in intermittent or locally isolated small-scale regions which correspond to the TCSs found in fast wind. However in slow wind, magnetic intermittent micro-structures are found to consist of mainly magnetic field directional turnings (MFDTs, Tu & Marsch, Ann. Geophysicae, 9, 319,1991) and rarely tangential current sheets (TCSs). The MFDTs are characterized by: (1) clear variation of the field component in the L dimension of the LMN coordinate system using the MVA method; (2) at least one of B_M or B_N is near to zero, or the velocity component V_L is near to zero; (3) the magnetic magnitude does not have a clear change; (4) no significant temperature and density peaks. The TCSs found in slow wind are not associated with prominent temperature enhancements. The TCSs found in both fast and slow wind may be created by turbulence interactions. The heating effect of TCSs in slow wind is weaker because the turbulence level is lower. The origin of the RDs in fast wind and the MFDTs in slow wind will be a topic for future studies. MFDTs may be observed when crossing a magnetic helical micro-tube, which may be formed due to tearing mode instability and magnetic multi-x-point reconnection in the slow wind.

  6. Large scale wind power penetration in Denmark

    DEFF Research Database (Denmark)

    Karnøe, Peter

    2013-01-01

    he Danish electricity generating system prepared to adopt nuclear power in the 1970s, yet has become the world's front runner in wind power with a national plan for 50% wind power penetration by 2020. This paper deploys a sociotechnical perspective to explain the historical transformation...... of "networks of power" via the interactions of politics, the techno-physics of electrons, and the market setting. The Danish case is about how an assemblage of new agencies has reorganized and reshaped society by building a new sociotechnical network. This has rendered developments highly unpredictable...

  7. Wind and tornado guidelines

    International Nuclear Information System (INIS)

    McDonald, J.R.

    1989-01-01

    The objective of the Department of Energy Natural Phenomena Hazards Project is to provide guidance and criteria for design of new facilities and for evaluation of existing ones subjected to extreme winds, earthquakes, and floods. This paper describes the treatment of wind and tornado hazards. Four facility-use categories are defined which represent increasing levels of risk to personnel or the environment in the event of a high wind event. Facilities are assigned to a particular category, depending on their mission, value, or toxic material content. The assigned facility-use category determines the design and evaluation criteria. The criteria are based on probabilistic hazard assessment. Performance goals are also specified for each facility-use category. A uniform approach to design wind loads, based on the ANSI A58.1-1982 standard, allows treatment of high winds and hurricane and tornado winds in a similar manner. Based on the wind hazard models, some sites must account for the possibility of tornadoes while others do not. Atmospheric pressure changes and missiles must be taken into account when considering tornadoes. The design and evaluation guidelines are designed to establish consistent levels of risk for different natural phenomena hazards and for facilities at different geographical locations

  8. Wind energy in Europe

    International Nuclear Information System (INIS)

    Sesto, E.

    1992-02-01

    Interest in wind energy as a supplementary source for the production of electricity has recently gained renewed momentum due to widespread concern about environmental impacts from the large scale use of fossil fuels and nuclear energy. In addition, political unrest in the Middle East has drawn attention to the importance of national energy self-sufficiency. European government administrations, however, have not yet fully appreciated the real worth of the 'clean energy' afforded by wind energy. In this regard, the European Wind Energy Association (EWEA) is acting as a strong voice to inform the public and energy planners by stimulating international wind energy R ampersand D cooperation, and organizing conferences to explain the advantages of wind energy. In October 1991, EWEA published a strategy document giving a picture of the real possibilities offered by wind energy within the geographical, social, and European economic context. This paper provides an overview of the more significant features to emerge from this document which represents a useful guideline for wind power plant technical/economic feasibility studies in that it contains brief notes on resource availability, land requirements, visual and acoustic impacts, turbine sizing, performance, interconnection to utility grids, maintenance and operating costs, safety, as well as, on marketing aspects

  9. Wind farms and planning

    International Nuclear Information System (INIS)

    Arkesteijn, L.; Havinga, R.; Benner, J.H.B.

    1992-01-01

    The siting of wind farms is becoming an increasingly important issue in the Netherlands. This paper gives an overview of the current situation concerning the planning of wind farms. We will pay attention to: Wind energy in official Dutch planning policy. To select the optimal sites, the government has made an administrative agreement with the 7 windy provinces. Nevertheless, wind energy is still fighting for a rightful position in physical planning policy. Some examples will illustrate this. Studies on siting and siting problems in the Netherlands. In order to gain more insight into aspects of wind farming several studies have been executed. In this paper special attention will be paid to the results of a study on the potential impact of large windturbine clusters on an existing agricutural area. Experiences with siting of wind farms in the Netherlands. Based on experiences with the planning and realization of farms, this paper gives the main problems. In the final part of the paper we present some general conclusions. Generally speaking, the knowledge is available for selecting optimal sites in the Netherlands. The basic problems for wind farming nowadays seem to be the visual impact and actually obtaining the ground. Nevertheless, there do seem to be enough sites for realizing the goals in the Netherlands. (au)

  10. Database on wind characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, K.S. [The Technical Univ. of Denmark (Denmark); Courtney, M.S. [Risoe National Lab., (Denmark)

    1999-08-01

    The organisations that participated in the project consists of five research organisations: MIUU (Sweden), ECN (The Netherlands), CRES (Greece), DTU (Denmark), Risoe (Denmark) and one wind turbine manufacturer: Vestas Wind System A/S (Denmark). The overall goal was to build a database consisting of a large number of wind speed time series and create tools for efficiently searching through the data to select interesting data. The project resulted in a database located at DTU, Denmark with online access through the Internet. The database contains more than 50.000 hours of measured wind speed measurements. A wide range of wind climates and terrain types are represented with significant amounts of time series. Data have been chosen selectively with a deliberate over-representation of high wind and complex terrain cases. This makes the database ideal for wind turbine design needs but completely unsuitable for resource studies. Diversity has also been an important aim and this is realised with data from a large range of terrain types; everything from offshore to mountain, from Norway to Greece. (EHS)

  11. Mongolia wind resource assessment project

    International Nuclear Information System (INIS)

    Elliott, D.; Chadraa, B.; Natsagdorj, L.

    1998-01-01

    The development of detailed, regional wind-resource distributions and other pertinent wind resource characteristics (e.g., assessment maps and reliable estimates of seasonal, diurnal, and directional) is an important step in planning and accelerating the deployment of wind energy systems. This paper summarizes the approach and methods being used to conduct a wind energy resource assessment of Mongolia. The primary goals of this project are to develop a comprehensive wind energy resource atlas of Mongolia and to establish a wind measurement program in specific regions of Mongolia to identify prospective sites for wind energy projects and to help validate some of the wind resource estimates. The Mongolian wind resource atlas will include detailed, computerized wind power maps and other valuable wind resource characteristic information for the different regions of Mongolia

  12. Type IV Wind Turbine Model

    DEFF Research Database (Denmark)

    Hansen, Anca Daniela; Margaris, Ioannis D.

    (WPP) will be considered. The aggregate WPP model, which will be based on the upscaling of the individual wind turbine model on the electrical part, will make use of an equivalent wind speed. The implemented model follows the basic structure of the generic standard Type 4 wind turbine model proposed...... by the International Electrotechnical Commission (IEC), in the IEC61400-27-1 Committee Draft for electrical simulation models for wind power generation, which is currently under review, [1]. The Type 4 wind turbine model described in this report includes a set of adjustments of the standard Type 4 wind turbine model...... project to be incorporated in the wind power plant level. This document describes the Type 4 wind turbine simulation model, implemented in the EaseWind project. The implemented wind turbine model is one of the initial necessary steps toward integrating new control services in the wind power plant level...

  13. 13 CFR Appendix A to Subpart A of... - Appendix A to Subpart A of Part 113

    Science.gov (United States)

    2010-01-01

    .... International Trade Program Small Business Act, sec. 22 and Pub. L. 96-481. Service Corps of Retired Executives... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Appendix A to Subpart A of Part 113 A Appendix A to Subpart A of Part 113 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION...

  14. 13 CFR Appendix A to Part 1171 - Appendix A to Part 1171

    Science.gov (United States)

    2010-01-01

    .... International Trade Program Small Business Act, section 22. Technical and Management Assistance Small Business... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Appendix A to Part 1171 A Appendix A to Part 1171 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION NONDISCRIMINATION IN...

  15. 13 CFR Appendix A to Part 112 - Appendix A to Part 112

    Science.gov (United States)

    2010-01-01

    ... development centers Small Business Act, sec. 21 and Pub. L. 96-302. International Trade Program Small Business... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Appendix A to Part 112 A Appendix A to Part 112 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION NONDISCRIMINATION IN...

  16. 40 CFR Appendix I to Subpart B of... - Appendix I to Subpart B of Part 205

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Appendix I to Subpart B of Part 205 I Appendix I to Subpart B of Part 205 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Medium and Heavy Trucks Pt...

  17. Satellite winds as a tool for offshore wind resource assessment: The Great Lakes Wind Atlas

    DEFF Research Database (Denmark)

    Doubrawa, Paula; Barthelmie, Rebecca Jane; Pryor, Sara C.

    2015-01-01

    This work presents a new observational wind atlas for the Great Lakes, and proposes a methodology to combine in situ and satellite wind observations for offshore wind resource assessment. Efficient wind energy projects rely on accurate wind resource estimates, which are complex to obtain offshore...... the North American Regional Reanalysis. Generalized wind climates are obtained for each buoy and coastal site with the wind model WAsP, and combined into a single wind speed estimate for the Great Lakes region. The method of classes is used to account for the temporal sparseness in the SAR data set...

  18. Wind for Schools: A Wind Powering America Project

    Science.gov (United States)

    US Department of Energy, 2007

    2007-01-01

    The U.S. Department of Energy's (DOE's) Wind Powering America program (based at the National Renewable Energy Laboratory) sponsors the Wind for Schools Project to raise awareness in rural America about the benefits of wind energy while simultaneously educating college seniors regarding wind energy applications. The three primary project goals of…

  19. Operation Design of Wind Turbines in Strong Wind Conditions

    DEFF Research Database (Denmark)

    Shen, Wen Zhong; Montes, Melissa Barroso; Odgaard, Peter Fogh

    2012-01-01

    and variable speed pitch regulated wind turbines. The variable speed design is more suitable for wind turbines to run at very high wind speeds which can help the turbine braking system to stop the turbine at the new "cut-out" wind speed. Reference power, rotational speed and pitch angle have been designed...

  20. Offshore wind speed and wind power characteristics for ten ...

    Indian Academy of Sciences (India)

    This paper utilizes wind speed data measured at 3 and 10 m above water surface level using buoys at 10 stations in Ionian and Aegean Seas to understand the behaviour of wind and thereafter energy yield at these stations using 5 MW rated power offshore wind turbine. With wind power densities of 971 and 693 W/m2 at ...