Atmospheric air density analysis with Meteo-40S wind monitoring system

Directory of Open Access Journals (Sweden)

Zahariea Dănuţ

2017-01-01

Full Text Available In order to estimate the wind potential of wind turbine sites, the wind resource maps can be used for mean annual wind speed, wind speed frequency distribution and mean annual wind power density determination. The general evaluation of the wind resource and the wind turbine ratings are based on the standard air density measured at sea level and at 15°C, ρs=1.225 kg/m3. Based on the experimental data obtained for a continental climate specific location, this study will present the relative error between the standard air density and the density of the dry and the moist air. Considering a cold day, for example on Friday 10th February 2017, on 1-second measurement rate and 10-minute measuring interval starting at 16:20, the mean relative errors obtained are 10.4145% for dry air, and 10.3634% for moist air. Based on these results, a correction for temperature, atmospheric air pressure and relative humidity should be always considered for wind resource assessment, as well as for the predicting the wind turbines performance.

AIR GAP CONTROL SYSTEM FOR HYDROGENERATORS

Directory of Open Access Journals (Sweden)

I. O. Zaitsev

2017-01-01

Full Text Available In this paper, we report of the solving the actual problem of control the air gap in the hydrogenerators. The aim of the study was development of a computerized information-measuring system for measuring the air gap in the hydrogenator, which used two capacitive sensors with parallel coplanar electrodes, and the method of determining the shape of the envelope parameters hydrogenerator rotor poles relative to the center axis of rotation, using the measurement results of the air gap.In practical studies of the sensor circuit it has been shown that its use allows for the informative value of the sensor capacitance conversion function to obtain a high accuracy and resolution measurement with digital linearization of converting function of the sensor with use program utility. To determine the form deviations of the envelope line of the rotor pole from the ideal cylinder, which is one of the main structural defects of the technological errors as results the distortion of the shape of the air gap in the hydrogenator, when the machine was manufacture and assembly. It is proposed to describe the shape of the envelope to use a Fourier transform. Calculation of the coefficients of the Fourier series is performed using the method of least squares as the regression coefficients.Application of this method in processing the measuring data in a computerized information-measuring system the developed with the primary converter with coplanar parallel electrodes allowed attaining the high measurement accuracy and resolution informative in magnitude of the capacity.

Waves in the Red Sea: Response to monsoonal and mountain gap winds

KAUST Repository

Ralston, David K.

2013-08-01

An unstructured grid, phase-averaged wave model forced with winds from a high resolution atmospheric model is used to evaluate wind wave conditions in the Red Sea over an approximately 2-year period. The Red Sea lies in a narrow rift valley, and the steep topography surrounding the basin steers the dominant wind patterns and consequently the wave climate. At large scales, the model results indicated that the primary seasonal variability in waves was due to the monsoonal wind reversal. During the winter, monsoon winds from the southeast generated waves with mean significant wave heights in excess of 2. m and mean periods of 8. s in the southern Red Sea, while in the northern part of the basin waves were smaller, shorter period, and from northwest. The zone of convergence of winds and waves typically occurred around 19-20°N, but the location varied between 15 and 21.5°N. During the summer, waves were generally smaller and from the northwest over most of the basin. While the seasonal winds oriented along the axis of the Red Sea drove much of the variability in the waves, the maximum wave heights in the simulations were not due to the monsoonal winds but instead were generated by localized mountain wind jets oriented across the basin (roughly east-west). During the summer, a mountain wind jet from the Tokar Gap enhanced the waves in the region of 18 and 20°N, with monthly mean wave heights exceeding 2. m and maximum wave heights of 14. m during a period when the rest of the Red Sea was relatively calm. Smaller mountain gap wind jets along the northeast coast created large waves during the fall and winter, with a series of jets providing a dominant source of wave energy during these periods. Evaluation of the wave model results against observations from a buoy and satellites found that the spatial resolution of the wind model significantly affected the quality of the wave model results. Wind forcing from a 10-km grid produced higher skills for waves than winds from a

Observing Boundary-Layer Winds from Hot-Air Balloon Flights

NARCIS (Netherlands)

Bruijn, de E.I.F.; Haan, de S.; Bosveld, F.C.; Wichers Schreur, B.G.J.; Holtslag, A.A.M.

2016-01-01

High-resolution upper-air wind observations are sparse, and additional observations are a welcome source of meteorological information. In this paper the potential of applying balloon flights for upper-air wind measurements is explored, and the meteorological content of this information is

Permanent-magnet-less machine having an enclosed air gap

Science.gov (United States)

Hsu, John S [Oak Ridge, TN

2012-02-07

A permanent magnet-less, brushless synchronous system includes a stator that generates a magnetic rotating field when sourced by an alternating current. An uncluttered rotor disposed within the magnetic rotating field is spaced apart from the stator to form an air gap relative to an axis of rotation. A stationary excitation core spaced apart from the uncluttered rotor by an axial air gap and a radial air gap substantially encloses the stationary excitation core. Some permanent magnet-less, brushless synchronous systems include stator core gaps to reduce axial flux flow. Some permanent magnet-less, brushless synchronous systems include an uncluttered rotor coupled to outer laminations. The quadrature-axis inductance may be increased in some synchronous systems. Some synchronous systems convert energy such as mechanical energy into electrical energy (e.g., a generator); other synchronous systems may convert any form of energy into mechanical energy (e.g., a motor).

Measured and modelled local wind field over a frozen lake in a mountainous area

Energy Technology Data Exchange (ETDEWEB)

Smedman, A.S.; Bergstroem, H.; Hoegstroem, U. [Uppsala Univ. (Sweden). Dept. of Meteorology

1996-03-01

The study is a follow-up of a previous paper and concentrates on two very characteristic flow regimes: forced channeling, where the driving geostrophic wind and the lake axis are roughly aligned, and pressure-driven channeling or gap winds, which are characterized by a geostrophic wind direction more or less perpendicular to the lake axis. Both situations produce winds along the main axis of the lake. In the forced channeling case the wind direction varies insignificantly with height and the wind speed increases monotonically with height. The gap wind flow, which can give supergeostrophic speed, is restricted to the lowest 500 m above the lake surface, drops in speed to near zero just above that layer, changing to an across-wind direction higher up. Gap winds are found to require slightly stable stratification for their existence; strong stability forces the flow to go round the mountains rather than over, and neutral conditions give a turbulent wake in the lee of the mountains. The gap wind starts at any occasion as a sudden warm front approaching from either of the two along-lake directions (115 or 295 degrees). It is argued that the relative warmth of the `gap wind air` is due to air originally flowing at mountain top height across the lake axis being gradually turned and accelerated along the synoptic pressure gradient while descending. The strongly sheared layer at the top of the gap wind region is dynamically highly unstable, giving rise to vertically coherent variations in wind speed and direction which appear to be triggered by gravity waves. When the driving geostrophic wind is high enough, the disturbed region reaches all the way down to the ground surface. Then periods with strong turbulence and low mean wind alternate with pronounced gap winds on typically a 10 minute scale. 11 refs, 18 figs

Optimization of air gap for two-dimensional imaging system using synchrotron radiation

Science.gov (United States)

Zeniya, Tsutomu; Takeda, Tohoru; Yu, Quanwen; Hyodo, Kazuyuki; Yuasa, Tetsuya; Aiyoshi, Yuji; Hiranaka, Yukio; Itai, Yuji; Akatsuka, Takao

2000-11-01

Since synchrotron radiation (SR) has several excellent properties such as high brilliance, broad continuous energy spectrum and small divergence, we can obtain x-ray images with high contrast and high spatial resolution by using of SR. In 2D imaging using SR, air gap method is very effective to reduce the scatter contamination. However, to use air gap method, the geometrical effect of finite source size of SR must be considered because spatial resolution of image is degraded by air gap. For 2D x-ray imaging with SR, x-ray mammography was chosen to examine the effect of air gap method. We theoretically discussed the optimization of air gap distance suing effective scatter point source model proposed by Muntz, and executed experiment with a newly manufactured monochromator with asymmetrical reflection and an imaging plate.

Calculations of air cooler for new subsonic wind tunnel

Science.gov (United States)

Rtishcheva, A. S.

2017-10-01

As part of the component development of TsAGI’s new subsonic wind tunnel where the air flow velocity in the closed test section is up to 160 m/sec hydraulic and thermal characteristics of air cooler are calculated. The air cooler is one of the most important components due to its highest hydraulic resistance in the whole wind tunnel design. It is important to minimize its hydraulic resistance to ensure the energy efficiency of wind tunnel fans and the cost-cutting of tests. On the other hand the air cooler is to assure the efficient cooling of air flow in such a manner as to maintain the temperature below 40 °C for seamless operation of measuring equipment. Therefore the relevance of this project is driven by the need to develop the air cooler that would demonstrate low hydraulic resistance of air and high thermal effectiveness of heat exchanging surfaces; insofar as the cooling section must be given up per unit time with the amount of heat Q=30 MW according to preliminary evaluations. On basis of calculation research some variants of air cooler designs are proposed including elliptical tubes, round tubes, and lateral plate-like fins. These designs differ by the number of tubes and plates, geometrical characteristics and the material of finned surfaces (aluminium or cooper). Due to the choice of component configurations a high thermal effectiveness is achieved for finned surfaces. The obtained results form the basis of R&D support in designing the new subsonic wind tunnel.

Fabrication of a printed capacitive air-gap touch sensor

Science.gov (United States)

Lee, Sang Hoon; Seo, Hwiwon; Lee, Sangyoon

2018-05-01

Unlike lithography-based processes, printed electronics does not require etching, which makes it difficult to fabricate electronic devices with an air gap. In this study, we propose a method to fabricate capacitive air-gap touch sensors via printing and coating. First, the bottom electrode was fabricated on a flexible poly(ethylene terephthalate) (PET) substrate using roll-to-roll gravure printing with silver ink. Then poly(dimethylsiloxane) (PDMS) was spin coated to form a sacrificial layer. The top electrode was fabricated on the sacrificial layer by spin coating with a stretchable silver ink. The sensor samples were then put in a tetrabutylammonium (TBAF) bath to generate the air gap by removing the sacrificial layer. The capacitance of the samples was measured for verification, and the results show that the capacitance increases in proportion to the applied force from 0 to 2.5 N.

Relative dose efficiencies of antiscatter grids and air gaps in pediatric radiography

International Nuclear Information System (INIS)

McDaniel, D.L.; Cohen, G.; Wagner, L.K.; Robinson, L.H.

1984-01-01

The relative dose efficiencies (RDE) of various antiscatter grids and air gaps were determined for conditions simulating those found in pediatric radiography, using phantoms representing a newborn child, a 5-yr-old and a 10-yr-old child. Our data indicate than an air gap is best for the newborn, due to the low levels of scatter. The 8:1 fiber grid or 15.2-cm air gap without a grid can improve dose efficiency (DE) for the 5-yr-old child by 20%--25% relative to the 3.3-cm air gap and no-grid technique, while for the 10-yr-old child, DE can be improved by 40% with an 8:1 fiber grid

Effect of air gap on uniformity of large-scale surface-wave plasma

International Nuclear Information System (INIS)

Lan Chaohui; Hu Xiwei; Jiang Zhonghe; Liu Minghai

2009-01-01

The effect of air gap on the uniformity of large-scale surface-wave plasma (SWP) in a rectangular chamber device is studied by using three-dimensional numerical analyses based on the finite difference time-domain (FDTD) approximation to Maxwell's equations and plasma fluid model. The spatial distributions of surface wave excited by slot-antenna array and the plasma parameters such as electron density and temperature are presented. For different air gap thicknesses, the results show that the existence of air gap would severely weaken the excitations of the surface wave and thereby the SWP. Thus the air gap should be eliminated completely in the design of the SWP source, which is opposite to the former research results. (authors)

Investigation of air flow in open-throat wind tunnels

Science.gov (United States)

Jacobs, Eastman N

1930-01-01

Tests were conducted on the 6-inch wind tunnel of the National Advisory Committee for Aeronautics to form a part of a research on open-throat wind tunnels. The primary object of this part of the research was to study a type of air pulsation which has been encountered in open-throat tunnels, and to find the most satisfactory means of eliminating such pulsations. In order to do this it was necessary to study the effects of different variable on all of the important characteristics of the tunnel. This paper gives not only the results of the study of air pulsations and methods of eliminating them, but also the effects of changing the exit-cone diameter and flare and the effects of air leakage from the return passage. It was found that the air pulsations in the 6-inch wind tunnel could be practically eliminated by using a moderately large flare on the exit cone in conjunction with leakage introduced by cutting holes in the exit cone somewhat aft of its minimum diameter.

Assessment of wind speed and wind power through three stations in Egypt, including air density variation and analysis results with rough set theory

International Nuclear Information System (INIS)

Essa, K.S.M.; Embaby, M.; Marrouf, A.A.; Koza, A.M.; Abd El-Monsef, M.E.

2007-01-01

It is well known that the wind energy potential is proportional to both air density and the third power of the wind speed average over a suitable time period. The wind speed and air density have random variables depending on both time and location. The main objective of this work is to derive the most general wind energy potential of the wind formulation putting into consideration the time variable in both wind speed and air density. The correction factor is derived explicitly in terms of the cross-correlation and the coefficients of variation.The application is performed for environmental and wind speed measurements at the Cairo Airport, Kosseir and Hurguada, Egypt. Comparisons are made between Weibull, Rayleigh, and actual data distributions of wind speed and wind power of one year 2005. A Weibull distribution is the best match to the actual probability distribution of wind speed data for most stations. The maximum wind energy potential was 373 W/m 2 in June at Hurguada (Red Sea coast) where the annual mean value was 207 W/m 2 . By Using Rough Set Theory, We Find That the Wind Power Depends on the Wind Speed with greater than air density

Lighter-than-air wind turbines in remote communities

Energy Technology Data Exchange (ETDEWEB)

Wilkins, M.; Ferguson, F.; Akhiwu, K. [Magenn Power Inc., Ottawa, ON (Canada)

2008-07-01

This paper presented the 100 kW Magenn Air Rotor System (MARS) drag-type wind turbine system that is based on lighter-than-air technology. It consists of an axisymmetric helium-filled core balloon, anchored to the ground via a tether containing high-tenacity fibers as well as copper conductors. The torque for the rotation is provided by sails fixed to the surface of the balloon. A winch on the ground allows the tether to be reeled in and out up to a height of 300 m. The feasibility of using the system in 2 specific local community-owned power network was investigated. The results of initial testing were discussed. Highly consistent winds at 300 m altitude were found to result in power densities 3 to 4 times what is available to a conventional 100 kW wind turbine. The inflatable structures reduce capital costs as well as equipment and shipping costs associated with installation in remote areas. It was concluded that the MARS system is very simple to install and despite its large size, no cranes or oversized vehicles are needed to deploy the system. The high-altitude wind power using tethered wind turbine devices has the potential to open up new wind resources in areas that are not served by conventional turbines. 6 refs., 3 tabs., 2 figs.

Design of a compressed air energy storage system for hydrostatic wind turbines

Directory of Open Access Journals (Sweden)

Ammar E. Ali

2018-03-01

Full Text Available Integration of Compressed Air Energy Storage (CAES system with a wind turbine is critical in optimally harvesting wind energy given the fluctuating nature of power demands. Here we consider the design of a CAES for a wind turbine with hydrostatic powertrain. The design parameters of the CAES are determined based on simulation of the integrated system model for a combination of these parameter values, namely the compression ratios of the air compressors and the expanders and the air tank size. The results of the simulations were used to choose the best design parameters, which would produce the best stable performance through increased energy output of the integrated CAES and wind turbine based on the intermittent wind profile. Simulation results for a 600 kW rated power wind turbine with integrated CAES indicate that increasing the tank size and compression ratio will improve the overall power quality through increased energy output up to a limit beyond which the power quality exhibits only marginal improvement.

Heat Transfer Enhancement of the Air-Cooling Tower with Rotating Wind Deflectors under Crosswind Conditions

Directory of Open Access Journals (Sweden)

Xueping Du

2018-04-01

Full Text Available To investigate the effect of wind deflectors on air flow and heat transfer performance of an air-cooling tower under crosswind conditions, an experimental system based on a surface condenser aluminum exchanger-type indirect air-cooling tower is established at a 1:100 proportional reduction. A 3-D computational fluid dynamics simulation model is built to study the air flow and temperature fields. The air flow rate into the cooling tower and the heat transfer rate of the radiators are used to evaluate cooling performance. Rotating wind deflectors are adopted to reduce the influence of crosswind on the cooling tower performance. The effects of the rotating wind deflectors on the thermal-hydraulic characteristics of the air-cooling tower under different environmental crosswind speeds are studied. Results indicate that the wind direction in the tower reverses as the rotating speed of the wind deflectors increases. The thermal performance of an air-cooling tower under crosswind conditions can be improved by using rotating wind deflectors. The heat transfer rate of a cooling tower with eight wind deflectors begins to increase when the rotating speed exceeds 2 r/min.

An Intelligent Harmonic Synthesis Technique for Air-Gap Eccentricity Fault Diagnosis in Induction Motors

Science.gov (United States)

Li, De Z.; Wang, Wilson; Ismail, Fathy

2017-11-01

Induction motors (IMs) are commonly used in various industrial applications. To improve energy consumption efficiency, a reliable IM health condition monitoring system is very useful to detect IM fault at its earliest stage to prevent operation degradation, and malfunction of IMs. An intelligent harmonic synthesis technique is proposed in this work to conduct incipient air-gap eccentricity fault detection in IMs. The fault harmonic series are synthesized to enhance fault features. Fault related local spectra are processed to derive fault indicators for IM air-gap eccentricity diagnosis. The effectiveness of the proposed harmonic synthesis technique is examined experimentally by IMs with static air-gap eccentricity and dynamic air-gap eccentricity states under different load conditions. Test results show that the developed harmonic synthesis technique can extract fault features effectively for initial IM air-gap eccentricity fault detection.

FEM Analysis of a New Electromechanical Converter with Rolling Rotor and Axial Air-Gap

Directory of Open Access Journals (Sweden)

UNGUREANU, C.

2015-11-01

Full Text Available The paper presents the modeling of a new type of electromechanical converter with rolling rotor (ECRR in order to obtain an optimisation at functional level. The ECRR prototype comprises a stator composed of twelve magnetic poles and a disk-shaped rolling rotor made of ferromagnetic material, without windings. Each magnetic pole is made of an E-shaped magnetic system and a winding placed on its central column. The electromechanical converter with rolling rotor is analyzed through a magnetic field study with Flux2D software in magnetostatic application. The field study examines the influence of the rotor thickness, axial air-gap size and current density on the magnetic attraction force that changes the position of the disk-shaped rolling rotor. Also, it is analyzed the variation of the magnetic attraction force for different inclination angles of the rolling rotor. The main advantage of the ECRR is represented by a low rotational speed without using mechanical gearboxes. The ECRR prototype can be used in photovoltaic panels tracking systems.

Using a New Modification on Wind Turbine Ventilator for Improving Indoor Air Quality

Directory of Open Access Journals (Sweden)

Louay Abdul salam Rasheed

2018-02-01

Full Text Available This paper describes a newly modified wind turbine ventilator that can achieve highly efficient ventilation. The new modification on the conventional wind turbine ventilator system may be achieved by adding a Savonius wind turbine above the conventional turbine to make it work more efficiently and help spinning faster. Three models of the Savonius wind turbine with 2, 3, and 4 blades' semicircular arcs are proposed to be placed above the conventional turbine of wind ventilator to build a hybrid ventilation turbine. A prototype of room model has been constructed and the hybrid turbine is placed on the head of the room roof. Performance's tests for the hybrid turbine with a different number of blades and different values of wind speeds have been conducted. The experimental test results show that the performance of the improved ventilation turbine with three blades is the best. It is found that the maximum rotation speed of the improved turbine is 107rpm, while the air flow rate is 0.0103m3/s and the air change rate per hour is 32.67hr-1, at a wind speed of 3m/s. The proposed design has been achieved an increase in the turbine rotational speed, increase of the extraction rate of the indoor air and the air-changes per hour, provided the requisite ventilation and improved the quality of the indoor air.

Effect of Air Gap Entrapped in Firefighter Protective Clothing on Thermal Resistance and Evaporative Resistance

Directory of Open Access Journals (Sweden)

He Hualing

2018-03-01

Full Text Available Heat and water vapor transfer behavior of thermal protective clothing is greatly influenced by the air gap entrapped in multilayer fabric system. In this study, a sweating hot plate method was used to investigate the effect of air gap position and size on thermal resistance and evaporative resistance of firefighter clothing under a range of ambient temperature and humidity. Results indicated that the presence of air gap in multilayer fabric system decreased heat and water vapor transfer abilities under normal wear. Moreover, the air gap position slightly influenced the thermal and evaporative performances of the firefighter clothing. In this study, the multilayer fabric system obtained the highest thermal resistance, when the air space was located at position B. Furthermore, the effect of ambient temperature on heat and water vapor transfer properties of the multilayer fabric system was also investigated in the presence of a specific air gap. It was indicated that ambient temperature did not influence the evaporative resistance of thermal protective clothing. A thermographic image was used to test the surface temperature of multilayer fabric system when an air gap was incorporated. These results suggested that a certain air gap entrapped in thermal protective clothing system could affect wear comfort.

Performance of a prototype micro wind turbine in the manmade wind field from air conditioner of buildings

Directory of Open Access Journals (Sweden)

K. H. Goh

2012-03-01

Full Text Available Harnessing waste energy from the manmade air fields of buildings presents a new area of renewable energy to explore. Due to the unpredictability of the natural wind, this study is to evaluate the practicality for harnessing waste energy from the air conditioner exhaust units which are a more constant and predictable source available in the buildings. A prototype of the micro wind turbine has been designed to minimize the negative effect of the exhaust sources. After the micro wind turbine was manufactured, the performance of the turbine was tested in the selected air conditioner exhaust unit. Increasing the rotor solidity and decreasing the resistance of the generator contribute to improved starting torque and decreased generator break in torque respectively in the design. The power generation of the micro wind turbine increases with an increase of the rotor speed. The 24-hour operation of the prototype presents an observation for both exhaust performance and power generation prediction when the prototype is mounted on the exhaust unit.

An Evaluation of Wind Turbine Technology at Peterson Air Force Base

Science.gov (United States)

2005-03-01

by the wind speed. Darrieus turbines are ordinarily inexpensive and are used for electricity generation and irrigation. One advantage to a...AN EVALUATION OF WIND TURBINE TECHNOLOGY...02 AN EVALUATION OF WIND TURBINE TECHNOLOGY AT PETERSON AIR FORCE BASE THESIS Presented to the Faculty Department of

Thermodynamic characteristics of a novel wind-solar-liquid air energy storage system

Science.gov (United States)

Ji, W.; Zhou, Y.; Sun, Y.; Zhang, W.; Pan, C. Z.; Wang, J. J.

2017-12-01

Due to the nature of fluctuation and intermittency, the utilization of wind and solar power will bring a huge impact to the power grid management. Therefore a novel hybrid wind-solar-liquid air energy storage (WS-LAES) system was proposed. In this system, wind and solar power are stored in the form of liquid air by cryogenic liquefaction technology and thermal energy by solar thermal collector, respectively. Owing to the high density of liquid air, the system has a large storage capacity and no geographic constraints. The WS-LAES system can store unstable wind and solar power for a stable output of electric energy and hot water. Moreover, a thermodynamic analysis was carried out to investigate the best system performance. The result shows that the increases of compressor adiabatic efficiency, turbine inlet pressure and inlet temperature all have a beneficial effect.

United States Air Force Academy (USAFA) Vertical Axis Wind Turbine.

Science.gov (United States)

1980-09-01

Rotors, SAND76-0131. Albuquerque: July 1977. 10. Oliver, R.C. and P.R. Nixon. "Design Procedure for Coupling Savonius and Darrieus Wind Turbines ", Air...May 17-20, 1976. -65- 16. Blackwell, B.F., R.E. Sheldahl, and L.V. Feltz. Wind Tunnel Performance Data for the Darrieus Wind Turbine with NACA 0012...a 5.8 m/s (13 mph) wind . At 100 rpm, the Darrieus turbine would be fully self-sustaining and acceleration would continue to an operating tip speed

Analysis of the wind data and estimation of the resultant air concentration rates

International Nuclear Information System (INIS)

Hu, Shze Jer; Katagiri, Hiroshi; Kobayashi, Hideo

1988-09-01

Statistical analyses and comparisons of the meteorological wind data obtained by the propeller and supersonic anemometers for the year of 1987 in the Japan Atomic Energy Research Institute, Tokai, were performed. For wind speeds less than 1 m/s, the propeller readings are generally 0.5 m/s less than those of the supersonic readings. The resultant average air concentration and ground level γ exposure rates due to the radioactive releases for the normal operation of a nuclear plant are over-estimated when calculated using the propeller wind data. As supersonic anemometer can give accurate wind speed to as low as 0.01 m/s, it should be used to measure the low wind speed. The difference in the average air concentrations and γ exposure rates calculated using the two different sets of wind data, is due to the influence of low wind speeds at calm. If the number at calm is large, actual low wind speeds and wind directions should be used in the statistical analysis of atmospheric dispersion to give a more accurate and realistic estimation of the air concentrations and γ exposure rates due to the normal operation of a nuclear plant. (author). 4 refs, 3 figs, 9 tabs

Vandenberg Air Force Base Pressure Gradient Wind Study

Science.gov (United States)

Shafer, Jaclyn A.

2013-01-01

Warning category winds can adversely impact day-to-day space lift operations at Vandenberg Air Force Base (VAFB) in California. NASA's Launch Services Program and other programs at VAFB use wind forecasts issued by the 30 Operational Support Squadron Weather Flight (30 OSSWF) to determine if they need to limit activities or protect property such as a launch vehicle. The 30 OSSWF tasked the AMU to develop an automated Excel graphical user interface that includes pressure gradient thresholds between specific observing stations under different synoptic regimes to aid forecasters when issuing wind warnings. This required the AMU to determine if relationships between the variables existed.

Zonal surface wind jets across the Red Sea due to mountain gap forcing along both sides of the Red Sea

KAUST Repository

Jiang, Houshuo

2009-01-01

[1] Mesoscale atmospheric modeling over the Red Sea, validated by in-situ meteorological buoy data, identifies two types of coastal mountain gap wind jets that frequently blow across the longitudinal axis of the Red Sea: (1) an eastward-blowing summer daily wind jet originating from the Tokar Gap on the Sudanese Red Sea coast, and (2) wintertime westward-blowing wind-jet bands along the northwestern Saudi Arabian coast, which occur every 10-20 days and can last for several days when occurring. Both wind jets can attain wind speeds over 15 m s-1 and contribute significantly to monthly mean surface wind stress, especially in the cross-axis components, which could be of importance to ocean eddy formation in the Red Sea. The wintertime wind jets can cause significant evaporation and ocean heat loss along the northeastern Red Sea coast and may potentially drive deep convection in that region. An initial characterization of these wind jets is presented. Copyright 2009 by the American Geophysical Union.

Air-gap Limitations and Bypass Techniques: “Command and Control” using Smart Electromagnetic Interferences

Directory of Open Access Journals (Sweden)

Chaouki Kasmi

2016-01-01

Full Text Available Air gaps are generally considered to be a very efficient information security protection. However, this technique also showed limitations, involving finding covert channels for bridging the air gap. Interestingly, recent publications have pointed out that a smart use of the intentional electromagnetic interferences introduced new threats for information security. In this paper, an innovative way for remotely communicating with a malware already installed on a computer by involving the induced perturbations is discussed leading to the design of a new air gap bridging covert channel.

The response of the Red Sea to a strong wind jet near the Tokar Gap in summer

KAUST Repository

Zhai, Ping; Bower, Amy

2013-01-01

[1] Remote sensing and in situ observations are used to investigate the ocean response to the Tokar Wind Jet in the Red Sea. The wind jet blows down the atmospheric pressure gradient through the Tokar Gap on the Sudanese coast, at about 19°N, during

CFD model of air movement in ventilated facade: comparison between natural and forced air flow

Energy Technology Data Exchange (ETDEWEB)

Mora Perez, Miguel; Lopez Patino, Gonzalo; Lopez Jimenez, P. Amparo [Hydraulic and Environmental Engineering Department, Universitat Politècnica de Valencia (Spain)

2013-07-01

This study describes computational fluid dynamics (CFD) modeling of ventilated facade. Ventilated facades are normal facade but it has an extra channel between the concrete wall and the (double skin) facade. Several studies found in the literature are carried out with CFD simulations about the behavior of the thermodynamic phenomena of the double skin facades systems. These studies conclude that the presence of the air gap in the ventilated facade affects the temperature in the building skin, causing a cooling effect, at least in low-rise buildings. One of the most important factors affecting the thermal effects of ventilated facades is the wind velocity. In this contribution, a CFD analysis applied on two different velocity assumptions for air movement in the air gap of a ventilated facade is presented. A comparison is proposed considering natural wind induced velocity with forced fan induced velocity in the gap. Finally, comparing temperatures in the building skin, the differences between both solutions are described determining that, related to the considered boundary conditions, there is a maximum height in which the thermal effect of the induced flow is significantly observed.

Measures against the adverse impact of natural wind on air-cooled condensers in power plant

Institute of Scientific and Technical Information of China (English)

无

2010-01-01

The natural wind plays disadvantageous roles in the operation of air-cooled steam condensers in power plant.It is of use to take various measures against the adverse effect of wind for the performance improvement of air-cooled condensers.Based on representative 2×600 MW direct air-cooled power plant,three ways that can arrange and optimize the flow field of cooling air thus enhance the heat transfer of air-cooled condensers were proposed.The physical and mathematical models of air-cooled condensers with various flow leading measures were presented and the flow and temperature fields of cooling air were obtained by CFD simulation.The back pressures of turbine were calculated for different measures on the basis of the heat transfer model of air-cooled condensers.The results show that the performance of air-cooled condensers is improved thus the back pressure of turbine is lowered to some extent by taking measures against the adverse impact of natural wind.

Requirements and Technology Advances for Global Wind Measurement with a Coherent Lidar: A Shrinking Gap

Science.gov (United States)

Kavaya, Michael J.; Kavaya, Michael J.; Yu, Jirong; Koch, Grady J.; Amzajerdian, Farzin; Singh, Upendra N.; Emmitt, G. David

2007-01-01

Early concepts to globally measure vertical profiles of vector horizontal wind from space planned on an orbit height of 525 km, a single pulsed coherent Doppler lidar system to cover the full troposphere, and a continuously rotating telescope/scanner that mandated a vertical line of sight wind profile from each laser shot. Under these conditions system studies found that laser pulse energies of approximately 20 J at 10 Hz pulse repetition rate with a rotating telescope diameter of approximately 1.5 m was required. Further requirements to use solid state laser technology and an eyesafe wavelength led to the relatively new 2-micron solid state laser. With demonstrated pulse energies near 20 mJ at 5 Hz, and no demonstration of a rotating telescope maintaining diffraction limited performance in space, the technology gap between requirements and demonstration was formidable. Fortunately the involved scientists and engineers set out to reduce the gap, and through a combination of clever ideas and technology advances over the last 15 years, they have succeeded. This paper will detail the gap reducing factors and will present the current status.

Effects of Armature Winding Segmentation with Multiple Converters on the Short Circuit Torque of 10-MW Superconducting Wind Turbine Generators

DEFF Research Database (Denmark)

Liu, Dong; Polinder, Henk; Abrahamsen, Asger Bech

2017-01-01

Superconducting synchronous generators (SCSGs) are drawing more attention in large direct-drive wind turbine applications. Despite low weight and compactness, the short circuit torque of an SCSG may be too high for wind turbine constructions due to a large magnetic air gap of an SCSG. This paper...... aims at assessing the effects of armature winding segmentation on reducing the short circuit torque of 10-MW SCSGs. A concept of armature winding segmentation with multiple power electronic converters is presented. Four SCSG designs using different topologies are examined. Results show that armature...... winding segmentation effectively reduce the short circuit torque in all the four SCSG designs when one segment is shorted at the terminal....

Combined effects of air temperature, wind, and radiation on the resting metabolism of avian raptors

International Nuclear Information System (INIS)

Hayes, S.R.

1978-01-01

American kestrels, Falco sparverius; red-tailed hawks, Buteo jamaicensis; and golden eagles, Aquila chrysaetos, were perched in a wind tunnel and subjected to various combinations of air temperature, wind, and radiation. Oxygen consumption was measured under the various combinations of environmental variables, and multiple regression equations were developed to predict resting metabolism as a function of body mass, air temperature, wind speed, and radiation load

The climate and air-quality benefits of wind and solar power in the United States

Science.gov (United States)

Millstein, Dev; Wiser, Ryan; Bolinger, Mark; Barbose, Galen

2017-09-01

Wind and solar energy reduce combustion-based electricity generation and provide air-quality and greenhouse gas emission benefits. These benefits vary dramatically by region and over time. From 2007 to 2015, solar and wind power deployment increased rapidly while regulatory changes and fossil fuel price changes led to steep cuts in overall power-sector emissions. Here we evaluate how wind and solar climate and air-quality benefits evolved during this time period. We find cumulative wind and solar air-quality benefits of 2015 US$29.7-112.8 billion mostly from 3,000 to 12,700 avoided premature mortalities, and cumulative climate benefits of 2015 US$5.3-106.8 billion. The ranges span results across a suite of air-quality and health impact models and social cost of carbon estimates. We find that binding cap-and-trade pollutant markets may reduce these cumulative benefits by up to 16%. In 2015, based on central estimates, combined marginal benefits equal 7.3 ¢ kWh-1 (wind) and 4.0 ¢ kWh-1 (solar).

Coefficients of resistance to cold-air-drainage winds on a grass-covered slope

International Nuclear Information System (INIS)

Komoda, H.; Kobayashi, T.; Mori, M.; Kaneko, T.

2006-01-01

The cold-air-drainage (CAD) wind is one of the most familiar local winds in Japan. It is driven by the surplus of density, or the deficit of potential temperature produced by radiative cooling in the surface air layer on a slope, and is resisted by the ground surface and the surrounding atmosphere. The coefficients of resistance of the ground surface and the surrounding atmosphere change with the CAD wind speed. The observations made on a grass-covered slope of Mt. Kuju showed that the resistance exerted by the surrounding atmosphere was much larger than that by the ground surface, and the sum of two coefficients of resistance decreased by one order of magnitude when the CAD wind speed exceeded some critical value

Dose optimization in pelvic radiography by air gap method on CR and DR systems – A phantom study

International Nuclear Information System (INIS)

Chan, C.T.P.; Fung, K.K.L.

2015-01-01

Objectives: This study aimed at investigating the feasibility of replacing the anti-scatter grid with an air gap at a pelvic radiographic examination in order to reduce patient dose while retaining diagnostic image quality. Methods: An anthropomorphic pelvis phantom was placed on a device that allowed the adjustment of different air gap thicknesses introduced between the phantom and the image receptor of Computed Radiography (CR) and Digital Radiography (DR) systems. Grid and non-grid images with different air gap thicknesses of both systems were produced. Ovary and testes doses were measured using thermoluminescent dosimeters. Radiographic quality of all images was rated by 5 experienced radiographers blindly using the Image Quality Score (IQS) and Visual Grading Analysis (VGA) systems. Results: Images of diagnostic quality were produced while the grid was replaced by a range of 0–25 cm air gap thickness in the pelvic radiographic examination. At non-grid examination with 10 cm air gap thickness, a maximum of relative dose reduction by 70.7% and 81.6% at CR; 68.6% and 79.4% at DR were achieved respectively at ovary and testes locations of the phantom as compared with their corresponding grid examinations. Conclusion: 10 cm was found to be the optimal air gap thickness at the tested pelvic examination. Effective dose was found to be reduced by 2 and 2.3 times respectively at the CR and DR examinations while the anti-scatter grid was replaced by 10 cm air gap. However, dose reduction effect by air gap method was found to be more pronounced in CR than in DR. - Highlights: • 10 cm air gap was found to be a substitute to replace grid in pelvic RANDO in CR/DR. • Over 68.6% of dose reduction effect were achieved at the ovary and testes regions. • Over 76.4% of reduction in effective dose were achieved at both the tested regions. • Dose reduction by air gap method was found to be more pronounced in CR than in DR

Band gap of two-dimensional fiber-air photonic crystals

Energy Technology Data Exchange (ETDEWEB)

Yang, Shu, E-mail: yangshu5678@163.com; Li, Masha

2016-04-15

A two-dimensional photonic crystal (PC) composed of textile fiber and air is initially discussed in this paper. Textile materials are so called soft materials, which are different from the previous PCs composed of rigid materials. The plain wave expansion method is used to calculate band structure of different PCs by altering component properties or structural parameters. Results show that the dielectric constant of textile fibers, fiber filling ratio and lattice arrangement are effective factors which influence PCs' band gap. Yet lattice constant and fiber diameter make inconspicuous influence on the band gap feature.

In depth analysis of the role of the mountain gap south of the Valley of Mexico on the air quality in Mexico City.

Science.gov (United States)

Gerardo Ruiz Suarez, Luis

2010-05-01

38 days of air quality observations in Tenango del Aire (TENAI), south of Mexico City during MILAGRO were analyzed. That site was managed by FQA-CCA-UNAM's team with a mobile laboratory equipped with standard air quality monitors: O3, NOx, NOy, CO, SO2 and surface meteorological parameters. Hosted additional instruments were: CH2O, column NO2 (DOAS), backscatter (Lidar) and pilot balloons. Also, an ultra light plane from IMK-IFU, equipped with O3, PM10, CN, Dew Point monitors flew around the Popocatepetl and Iztaccihuatl volcanoes and above of TENAI some days during MILAGRO. Atop of TENAI, the ultra light descended in spiral until near ground and ascended to resume its path. In addition to these measurements, UNAM team ran air quality numerical simulations using the Mesoscale Climate and Chemistry Model (MCCM) and an online coupled Wind Erosion Processor to MCCM we call WEPS-MCCM. The combined observations on the ground, the ultra light plane and the models results enabled us to carry out an in depth analysis of air quality in such important region south of Mexico City. Comparison were made with the episodes classification proposed by De Foy; Ozone North and South, Convection North and South, Cold Surge and South Venting to characterize dynamics in the Valley of Mexico. The aim was to define how well connected is TENAI with the air quality network in the MCMA. The influence of the mountain gap on ozone and PM10 levels in Mexico City is analyzed by episode type. Also, the impact of the mega city of Mexico on the nearby region to the south can be understood by observations in TENAI. More polluted episode types in TENAI are those called: Cold Surge, Ozone South and South Venting due to a wind shift occurring in early afternoon that brings back polluted air that was drained south during the morning and returns back to TENAI rich in aged air parcels. March 17 was chosen to show the integrated analysis of all variables observed and modeled (MCCM) in TENAI. In that day

Response of reptile and amphibian communities to canopy gaps created by wind disturbance in the Southern Appalachians

Science.gov (United States)

Cathryn H. Greenberg

2001-01-01

Reptile and amphibian communities were sampled in intact gaps created by wind disturbance, salvage-logged gaps, and closed canopy mature forest (controls). Sampling was conducted during June–October in 1997 and 1998 using drift fences with pitfall and funnel traps. Basal area of live trees, shade, leaf litter coverage, and litter depth was highest in controls and...

Wind Energy and Air Emission Reduction Benefits: A Primer

Energy Technology Data Exchange (ETDEWEB)

Jacobson, D.; High, C.

2008-02-01

This document provides a summary of the impact of wind energy development on various air pollutants for a general audience. The core document addresses the key facts relating to the analysis of emission reductions from wind energy development. It is intended for use by a wide variety of parties with an interest in this issue, ranging from state environmental officials to renewable energy stakeholders. The appendices provide basic background information for the general reader, as well as detailed information for those seeking a more in-depth discussion of various topics.

A Zooming Technique for Wind Transport of Air Pollution

NARCIS (Netherlands)

Berkvens, P.J.F.; Bochev, Mikhail A.; Lioen, W.; Verwer, J.G.

In air pollution dispersion models, typically systems of millions of equations that describe wind transport, chemistry and vertical mixing have to be integrated in time. To have more accurate results over specific fixed areas of interest---usually highly polluted areas with intensive emissions---a

A zooming technique for wind transport of air pollution

NARCIS (Netherlands)

Vilsmeier, R.; Berkvens, P.J.F.; Benkhaldoun, F.; Bochev, Mikhail A.; Lioen, W.M.; Haenel, D.; Verwer, J.G.

1999-01-01

In air pollution dispersion models, typically systems of millions of equations that describe wind transport, chemistry and vertical mixing have to be integrated in time. To have more accurate results over specific fixed areas of interest---usually highly polluted areas with intensive emissions---a

Investigation of the spatial variability and possible origins of wind-induced air pressure fluctuations responsible for pressure pumping

Science.gov (United States)

Mohr, Manuel; Laemmel, Thomas; Maier, Martin; Zeeman, Matthias; Longdoz, Bernard; Schindler, Dirk

2017-04-01

The exchange of greenhouse gases between the soil and the atmosphere is highly relevant for the climate of the Earth. Recent research suggests that wind-induced air pressure fluctuations can alter the soil gas transport and therefore soil gas efflux significantly. Using a newly developed method, we measured soil gas transport in situ in a well aerated forest soil. Results from these measurements showed that the commonly used soil gas diffusion coefficient is enhanced up to 30% during periods of strong wind-induced air pressure fluctuations. The air pressure fluctuations above the forest floor are only induced at high above-canopy wind speeds (> 5 m s-1) and lie in the frequency range 0.01-0.1 Hz. Moreover, the amplitudes of air pressure fluctuations in this frequency range show a clear quadratic dependence on mean above-canopy wind speed. However, the origin of these wind-induced pressure fluctuations is still unclear. Airflow measurements and high-precision air pressure measurements were conducted at three different vegetation-covered sites (conifer forest, deciduous forest, grassland) to investigate the spatial variability of dominant air pressure fluctuations, their origin and vegetation-dependent characteristics. At the conifer forest site, a vertical profile of air pressure fluctuations was measured and an array consisting of five pressure sensors were installed at the forest floor. At the grassland site, the air pressure measurements were compared with wind observations made by ground-based LIDAR and spatial temperature observations from a fibre-optic sensing network (ScaleX Campaign 2016). Preliminary results show that at all sites the amplitudes of relevant air pressure fluctuations increase with increasing wind speed. Data from the array measurements reveal that there are no time lags between the air pressure signals of different heights, but a time lag existed between the air pressure signals of the sensors distributed laterally on the forest floor

Measurements of Coastal Winds and Temperature. Sensor Evaluation, Data Quality, and Wind Structures

Energy Technology Data Exchange (ETDEWEB)

Heggem, Tore

1997-12-31

The long Norwegian coastline has excellent sites for wind power production. This thesis contains a documentation of a measurement station for maritime meteorological data at the coast of Mid-Norway, and analysis of temperature and wind data. It discusses experience with different types of wind speed and wind direction sensors. Accurate air temperature measurements are essential to obtain information about the stability of the atmosphere, and a sensor based on separately calibrated thermistors is described. The quality of the calibrations and the measurements is discussed. A database built up from measurements from 1982 to 1995 has been available. The data acquisition systems and the programs used to read the data are described, as well as data control and gap-filling methods. Then basic statistics from the data like mean values and distributions are given. Quality control of the measurements with emphasis on shade effects from the masts and direction alignment is discussed. The concept of atmospheric stability is discussed. The temperature profile tends to change from unstable to slightly stable as maritime winds passes land. Temperature spectra based on two-year time series are presented. Finally, there is a discussion of long-term turbulence spectra calculated from 14 years of measurements. The lack of a gap in the one-hour region of the spectra is explained from the overweight of unstable atmospheric conditions in the dominating maritime wind. Examples of time series with regular 40-minute cycles, and corresponding effect spectra are given. The validity of local lapse rate as a criterion of atmospheric stability is discussed. 34 refs., 86 figs., 11 tabs.

Measurements of Coastal Winds and Temperature. Sensor Evaluation, Data Quality, and Wind Structures

Energy Technology Data Exchange (ETDEWEB)

Heggem, Tore

1998-12-31

The long Norwegian coastline has excellent sites for wind power production. This thesis contains a documentation of a measurement station for maritime meteorological data at the coast of Mid-Norway, and analysis of temperature and wind data. It discusses experience with different types of wind speed and wind direction sensors. Accurate air temperature measurements are essential to obtain information about the stability of the atmosphere, and a sensor based on separately calibrated thermistors is described. The quality of the calibrations and the measurements is discussed. A database built up from measurements from 1982 to 1995 has been available. The data acquisition systems and the programs used to read the data are described, as well as data control and gap-filling methods. Then basic statistics from the data like mean values and distributions are given. Quality control of the measurements with emphasis on shade effects from the masts and direction alignment is discussed. The concept of atmospheric stability is discussed. The temperature profile tends to change from unstable to slightly stable as maritime winds passes land. Temperature spectra based on two-year time series are presented. Finally, there is a discussion of long-term turbulence spectra calculated from 14 years of measurements. The lack of a gap in the one-hour region of the spectra is explained from the overweight of unstable atmospheric conditions in the dominating maritime wind. Examples of time series with regular 40-minute cycles, and corresponding effect spectra are given. The validity of local lapse rate as a criterion of atmospheric stability is discussed. 34 refs., 86 figs., 11 tabs.

Role of preoperative air-bone gap in tinnitus outcome after tympanoplasty for chronic otitis media with tinnitus.

Science.gov (United States)

Kim, Hong Chan; Jang, Chul Ho; Kim, Young Yoon; Seong, Jong Yuap; Kang, Sung Hoon; Cho, Yong Beom

Previous reports indicated that middle ear surgery might partially improve tinnitus after surgery. However, until now, no influencing factor has been determined for tinnitus outcome after middle ear surgery. The purpose of this study was to investigate the association between preoperative air-bone gap and tinnitus outcome after tympanoplasty type I. Seventy-five patients with tinnitus who had more than 6 months of symptoms of chronic otitis media on the ipsilateral side that were refractory to medical treatment were included in this study. All patients were evaluated through otoendoscopy, pure tone/speech audiometer, questionnaire survey using the visual analog scale and the tinnitus handicap inventory for tinnitus symptoms before and 6 months after tympanoplasty. The influence of preoperative bone conduction, preoperative air-bone-gap, and postoperative air-bone-gap on tinnitus outcome after the operation was investigated. The patients were divided into two groups based on preoperative bone conduction of less than 25dB (n=50) or more than 25dB (n=25). The postoperative improvement of tinnitus in both groups showed statistical significance. Patients whose preoperative air-bone-gap was less than 15dB showed no improvement in postoperative tinnitus using the visual analog scale (p=0.889) and the tinnitus handicap inventory (p=0.802). However, patients whose preoperative air-bone-gap was more than 15dB showed statistically significant improvement in postoperative tinnitus using the visual analog scale (ptinnitus handicap inventory (p=0.016). Postoperative change in tinnitus showed significance compared with preoperative tinnitus using visual analog scale (p=0.006). However, the correlation between reduction in the visual analog scale score and air-bone-gap (p=0.202) or between reduction in tinnitus handicap inventory score and air-bone-gap (p=0.290) was not significant. We suggest that the preoperative air-bone-gap can be a predictor of tinnitus outcome after

Treatment Wetland Aeration without Electricity? Lessons Learned from the First Experiment Using a Wind-Driven Air Pump

Directory of Open Access Journals (Sweden)

Johannes Boog

2016-11-01

Full Text Available Aerated treatment wetlands have become an increasingly recognized technology for treating wastewaters from domestic and various industrial origins. To date, treatment wetland aeration is provided by air pumps which require access to the energy grid. The requirement for electricity increases the ecological footprint of an aerated wetland and limits the application of this technology to areas with centralized electrical infrastructure. Wind power offers another possibility as a driver for wetland aeration, but its use for this purpose has not yet been investigated. This paper reports the first experimental trial using a simple wind-driven air pump to replace the conventional electric air blowers of an aerated horizontal subsurface flow wetland. The wind-driven air pump was connected to a two-year old horizontal flow aerated wetland which had been in continuous (24 h aeration since startup. The wind-driven aeration system functioned, however it was not specifically adapted to wetland aeration. As a result, treatment performance decreased compared to prior continuous aeration. Inconsistent wind speed at the site may have resulted in insufficient pressure within the aeration manifold, resulting in insufficient air supply to the wetland. This paper discusses the lessons learned during the experiment.

Long-range transport of air pollution under light gradient wind conditions

International Nuclear Information System (INIS)

Kurita, H.; Sasaki, K.; Muroga, H.; Ueda, H.; Wakamatsu, S.

1985-01-01

The long-range transport of air pollution on clear days under light gradient wind conditions is investigated from an analysis of all days with high oxidant concentrations in 1979 at locations in central Japan that are far from pollutant sources. Surface-level wind and pressure distributions over a 300 x 300 km area were analyzed, together with concentration isopleths of oxidants and suspended particles produced by photochemical reactions

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

Capabilities and Gaps Assessments of Urban Air Quality Manage-ment in Uganda

OpenAIRE

Amin Tamale Kiggundu

2015-01-01

Today, large cities across the globe are facing a pervasive problem of air pollution.  The purpose of this study is to assess the capabilities and gaps in urban air quality management in Uganda as well as proposing strategies for curbing air pollution. This study applied face to face interviews, targeting key informants such as the environmental experts, urbanization researchers and officials from the National Environment Management Authority (NEMA). Results show that rapid motorization, cont...

Impulse breakdown of small air gap in electric field Part I: Influence ...

African Journals Online (AJOL)

The influence of barrier position on breakdown voltage in air dielectric has been investigated. Needle and Cone positive point electrodes were used and the effects of electrode curvature on barrier position for maximum breakdown voltage were compared, with air gap for the point to plane electrode fixed at 10 cm for all the ...

Design, dimensioning and control of a synchronous motor/generator with homopolar excitation and coils inside the air gap for electromechanical energy accumulator; Conception, dimensionnement et commande d'un moteur/generateur synchrone a excitation homopolaire et a bobinages dans l'entrefer pour accumulateur electromecanique d'energie

Energy Technology Data Exchange (ETDEWEB)

Bernard, N.

2001-12-15

A new axial field machine with armature and field windings fixed in the air-gap is studied. A double face printed winding is presented and a new tool, using a surface permeance model is developed. A simplified current control is proposed. Finally, considering the association synchronous machine-inverter the loss minimization problem is investigated, including both geometry and command parameters. (author)

Toward an Educational Sphereology: Air, Wind, and Materialist Pedagogy

Science.gov (United States)

Ford, Derek R.; Zhao, Weili

2018-01-01

It's not uncommon for people to make reference to atmospheres, including in relationship with educational spaces. In this article, we investigate educational atmospheres by turning to Western and Chinese literature on the air and wind. We pursue this task in three phases. First, we examine the Western literature to see the possible strings of…

Effect of real-time boundary wind conditions on the air flow and pollutant dispersion in an urban street canyon—Large eddy simulations

Science.gov (United States)

Zhang, Yun-Wei; Gu, Zhao-Lin; Cheng, Yan; Lee, Shun-Cheng

2011-07-01

Air flow and pollutant dispersion characteristics in an urban street canyon are studied under the real-time boundary conditions. A new scheme for realizing real-time boundary conditions in simulations is proposed, to keep the upper boundary wind conditions consistent with the measured time series of wind data. The air flow structure and its evolution under real-time boundary wind conditions are simulated by using this new scheme. The induced effect of time series of ambient wind conditions on the flow structures inside and above the street canyon is investigated. The flow shows an obvious intermittent feature in the street canyon and the flapping of the shear layer forms near the roof layer under real-time wind conditions, resulting in the expansion or compression of the air mass in the canyon. The simulations of pollutant dispersion show that the pollutants inside and above the street canyon are transported by different dispersion mechanisms, relying on the time series of air flow structures. Large scale air movements in the processes of the air mass expansion or compression in the canyon exhibit obvious effects on pollutant dispersion. The simulations of pollutant dispersion also show that the transport of pollutants from the canyon to the upper air flow is dominated by the shear layer turbulence near the roof level and the expansion or compression of the air mass in street canyon under real-time boundary wind conditions. Especially, the expansion of the air mass, which features the large scale air movement of the air mass, makes more contribution to the pollutant dispersion in this study. Comparisons of simulated results under different boundary wind conditions indicate that real-time boundary wind conditions produces better condition for pollutant dispersion than the artificially-designed steady boundary wind conditions.

An investigation of drag reduction for tractor trailer vehicles with air deflector and boattail. [wind tunnel tests

Science.gov (United States)

Muirhead, V. U.

1981-01-01

A wind tunnel investigation was conducted to determine the influence of several physical variables on the aerodynamic drag of a trailer model. The physical variables included: a cab mounted wind deflector, boattail on trailer, flow vanes on trailer front, forced transition on trailer, and decreased gap between tractor and trailer. Tests were conducted at yaw angles (relative wind angles) of 0, 5, 10, 20, and 30 degrees and Reynolds numbers of 3.58 x 10 to the 5th power 6.12 x 10 to the 5th power based upon the equivalent diameter of the vehicles. The wind deflector on top of the cab produced a calculated reduction in fuel consumption of about 5 percent of the aerodynamic portion of the fuel budget for a wind speed of 15.3 km/hr (9.5 mph) over a wind angle range of 0 deg to 180 deg and for a vehicle speed of 88.5 km/hr (55 mph). The boattail produced a calculated 7 percent to 8 percent reduction in fuel consumption under the same conditions. The decrease in gap reduced the calculated fuel consumption by about 5 percent of the aerodynamic portion of the fuel budget.

Air Gaps, Size Effect, and Corner-Turning in Ambient LX-17

Energy Technology Data Exchange (ETDEWEB)

Souers, P C; Hernandez, A; Cabacungan, C; Fried, L; Garza, R; Glaesemann, K; Lauderbach, L; Liao, S; Vitello, P

2008-02-05

Various ambient measurements are presented for LX-17. The size (diameter) effect has been measured with copper and Lucite confinement, where the failure radii are 4.0 and 6.5 mm, respectively. The air well corner-turn has been measured with an LX-07 booster, and the dead-zone results are comparable to the previous TATB-boosted work. Four double cylinders have been fired, and dead zones appear in all cases. The steel-backed samples are faster than the Lucite-backed samples by 0.6 {micro}s. Bare LX-07 and LX-17 of 12.7 mm-radius were fired with air gaps. Long acceptor regions were used to truly determine if detonation occurred or not. The LX-07 crossed at 10 mm with a slight time delay. Steady state LX-17 crossed at 3.5 mm gap but failed to cross at 4.0 mm. LX-17 with a 12.7 mm run after the booster crossed a 1.5 mm gap but failed to cross 2.5 mm. Timing delays were measured where the detonation crossed the gaps. The Tarantula model is introduced as embedded in 0 reactive flow JWL++ and Linked Cheetah V4, mostly at 4 zones/mm. Tarantula has four pressure regions: off, initiation, failure and detonation. The physical basis of the input parameters is considered.

30 CFR 285.659 - What requirements must I include in my SAP, COP, or GAP regarding air quality?

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 2 2010-07-01 2010-07-01 false What requirements must I include in my SAP, COP, or GAP regarding air quality? 285.659 Section 285.659 Mineral Resources MINERALS MANAGEMENT SERVICE... must I include in my SAP, COP, or GAP regarding air quality? (a) You must comply with the Clean Air Act...

A Method to Quantify the Wind and Non-wind Contribution to Year-to-year Air Quality Variation and its Application in China

Science.gov (United States)

LI, Y.; Lau, A. K. H.; Wong, A.; Fung, J. C. H.

2017-12-01

Changes in emissions and wind are often identified as the two dominant factors contributing to year-to-year variations in the concentration of primary pollutants. However, because changes in wind and emissions are intertwined, it has been difficult to quantitatively differentiate their effects on air quality directly from observed data. In particular, if the annual mean concentration of pollutants is higher than the previous year, it is difficult to identify whether the deterioration in air quality is caused by wind blowing from more polluted regions or an increase in contributing emissions. In this paper, based on wind and pollution roses, we propose a method to differentiate the effects of wind and non-wind (e.g., emissions) changes using direct observation. An index (L) is first defined to quantify the validity of the linear decomposition. The method is then validated by idealized experiments, numerical experiments and a two-year observation dataset from an actual emissions control program. Finally, we demonstrate the proposed method by studying long-term PM10 variations in Hong Kong during 2000-2011. We find that for most of the period, the linear decomposition of the changes in annual PM10 is valid (up to 90% confidence) and is dominated by the change in non-wind effects (e.g., emissions), whereas the average absolute effect from the wind variability is about 20%. Sensitivity analyses also suggest that our method should work in any location as long as the observed wind and pollution data have sufficient duration and resolution to resolve the corresponding wind and pollution roses. The method is applied for estimating the control effectiveness of the intervention programs in the Shanghai Expo, the longest socioeconomic international event held in China. The results show that integrated effect of control policies taken for improving the air quality in Shanghai are significantly effective for PM10 reduction and also effective for SO2 reduction, whereas the

Gearless wind power generator

Energy Technology Data Exchange (ETDEWEB)

Soederlund, L.; Ridanpaeae, P.; Vihriaelae, H.; Peraelae, R. [Tampere Univ. of Technology (Finland). Lab. of Electricity and Magnetism

1998-10-01

In the project a 100 kW axial flux permanent magnet wind power generator has been designed. The toroidal stator with air gap winding is placed between two rotating discs with permanent magnets. The magnet material is NdBFe due to its excellent magnetic properties compared to other materials. This type of topology enables a very large number of poles compared to conventional machine of the same size. A large number of poles is required to achieve a low rotational speed and consequently a direct driven system. The stator winding is formed by rectangular coils. The end winding is very short leading to small resistive losses. On the other hand, the absence of iron teeth causes eddy current losses in the conductors. These can be restricted to an acceptable level by keeping the wire diameter and flux density small. This means that the number of phases should be large. Several independent three phase systems may be used. The toothless stator also means that the iron losses are small and there exists no cogging torque

Optimal Wind Corrected Flight Path Planning for Autonomous Micro Air Vehicles

National Research Council Canada - National Science Library

Zollars, Michael D

2007-01-01

...) fixed sensor on a target in the presence of a constant wind. Autonomous flight is quickly becoming the future of air power and over the past several years, the size and weight of autonomous vehicles has decreased dramatically...

Air/sea DMS gas transfer in the North Atlantic: evidence for limited interfacial gas exchange at high wind speed

Science.gov (United States)

Bell, T. G.; De Bruyn, W.; Miller, S. D.; Ward, B.; Christensen, K.; Saltzman, E. S.

2013-05-01

Shipboard measurements of eddy covariance DMS air/sea fluxes and seawater concentration were carried out in the North Atlantic bloom region in June/July 2011. Gas transfer coefficients (k660) show a linear dependence on mean horizontal wind speed at wind speeds up to 11 m s-1. At higher wind speeds the relationship between k660 and wind speed weakens. At high winds, measured DMS fluxes were lower than predicted based on the linear relationship between wind speed and interfacial stress extrapolated from low to intermediate wind speeds. In contrast, the transfer coefficient for sensible heat did not exhibit this effect. The apparent suppression of air/sea gas flux at higher wind speeds appears to be related to sea state, as determined from shipboard wave measurements. These observations are consistent with the idea that long waves suppress near surface water side turbulence, and decrease interfacial gas transfer. This effect may be more easily observed for DMS than for less soluble gases, such as CO2, because the air/sea exchange of DMS is controlled by interfacial rather than bubble-mediated gas transfer under high wind speed conditions.

An improved model of induction motors for diagnosis purposes - Slot skewing effect and air-gap eccentricity faults

Energy Technology Data Exchange (ETDEWEB)

Ghoggal, A.; Zouzou, S.E.; Sahraoui, M. [Laboratoire de genie electrique de Biskra, Departement d' electrotechnique, Universite Mohamed Khider, BP 145, Biskra (Algeria); Razik, H. [Groupe de Recherche en Electrotechnique et Electronique de Nancy, Universite Henri Poincare, Faculte des Sciences et Techniques, BP 239, F-54506 Vandoeuvre-les-Nancy (France); Khezzar, A. [Laboratoire d' Electrotechnique de Constantine, Universite Mentouri, Constantine (Algeria)

2009-05-15

This paper describes an improved method for the modeling of axial and radial eccentricities in induction motors (IM). The model is based on an extension of the modified winding function approach (MWFA) which allows for all harmonics of the magnetomotive force (MMF) to be taken into account. It is shown that a plane view of IM gets easily the motor inductances and reduces considerably the calculation process. The described technique includes accurately the slot skewing effect and leads to pure analytical expressions of the inductances in case of radial eccentricity. In order to model the static, dynamic or mixed axial eccentricity, three suitable alternatives are explained. Unlike the previous proposals, the discussed alternatives take into account all the harmonics of the inverse of air-gap function without any development in Fourier series. Simulation results as well as experimental verifications prove the usefulness and the effectiveness of the proposed model. (author)

An improved model of induction motors for diagnosis purposes - Slot skewing effect and air-gap eccentricity faults

International Nuclear Information System (INIS)

Ghoggal, A.; Zouzou, S.E.; Razik, H.; Sahraoui, M.; Khezzar, A.

2009-01-01

This paper describes an improved method for the modeling of axial and radial eccentricities in induction motors (IM). The model is based on an extension of the modified winding function approach (MWFA) which allows for all harmonics of the magnetomotive force (MMF) to be taken into account. It is shown that a plane view of IM gets easily the motor inductances and reduces considerably the calculation process. The described technique includes accurately the slot skewing effect and leads to pure analytical expressions of the inductances in case of radial eccentricity. In order to model the static, dynamic or mixed axial eccentricity, three suitable alternatives are explained. Unlike the previous proposals, the discussed alternatives take into account all the harmonics of the inverse of air-gap function without any development in Fourier series. Simulation results as well as experimental verifications prove the usefulness and the effectiveness of the proposed model.

Investigation of pulsed barrier discharge in water-air gap

International Nuclear Information System (INIS)

Taran, V.S.; Krasnyj, V.V.; Lozina, A.S.; Shvets, O.M.

2013-01-01

This article presents the results of the use of a pulsed dielectric barrier discharge with water electrode and diaphragm. The spectroscopic and electrical investigations of such discharge were conducted. The ozone concentration in an aqueous solution comprised 0.7 mg/l with high-voltage pulsed power at 120 W. The discharge reviewed emission spectrum lines of molecular nitrogen and hydroxyl radicals in the range of 200...800 nm in the water-air gap. The intensity changing of luminescence lines of OH and N 2 singles depending on the applied voltage and discharge gap has been determined. Aqueous solution of indigo was used in order to determine the impact level on the organic material. Experiments on inactivation of test E. coli cultures have been carried out.

Production of 150nm wide Air Gap Interconnects with a "Sacrificial Materials Approach" and a "Close-off Approach"

NARCIS (Netherlands)

Daamen, R.; Pamler, W.

2005-01-01

The dielectric constant of a metallization system can be reduced drastically by introduction of air gaps between metal lines. It was the objective of the activities reported here to demonstrate processes that allow to incorporate air gaps in single-metal layer structures. Two different methods

Thermodynamic analysis of a novel hybrid wind-solar-compressed air energy storage system

International Nuclear Information System (INIS)

Ji, Wei; Zhou, Yuan; Sun, Yu; Zhang, Wu; An, Baolin; Wang, Junjie

2017-01-01

Highlights: • We present a novel hybrid wind-solar-compressed air energy storage system. • Wind and solar power are transformed into stable electric energy and hot water. • The system output electric power is 8053 kWh with an exergy efficiency of 65.4%. • Parametric sensitivity analysis is presented to optimize system performance. - Abstract: Wind and solar power have embraced a strong development in recent years due to the energy crisis in China. However, owing to their nature of fluctuation and intermittency, some power grid management problems can be caused. Therefore a novel hybrid wind-solar-compressed air energy storage (WS-CAES) system was proposed to solve the problems. The WS-CAES system can store unstable wind and solar power for a stable output of electric energy and hot water. Also, combined with organic Rankin cycle (ORC), the cascade utilization of energy with different qualities was achieved in the WS-CAES system. Aiming to obtain the optimum performance, the analysis of energy, exergy and parametric sensitivity were all conducted for this system. Furthermore, exergy destruction ratio of each component in the WS-CAES system was presented. The results show that the electric energy storage efficiency, round trip efficiency and exergy efficiency can reach 87.7%, 61.2% and 65.4%, respectively. Meanwhile, the parameters analysis demonstrates that the increase of ambient temperature has a negative effect on the system performance, while the increase of turbine inlet temperature has a positive effect. However, when the air turbine inlet pressure varies, there is a tradeoff between the system performance and the energy storage density.

The effect of body postures on the distribution of air gap thickness and contact area.

Science.gov (United States)

Mert, Emel; Psikuta, Agnes; Bueno, Marie-Ange; Rossi, René M

2017-02-01

The heat and mass transfer in clothing is predominantly dependent on the thickness of air layer and the magnitude of contact area between the body and the garment. The air gap thickness and magnitude of the contact area can be affected by the posture of the human body. Therefore, in this study, the distribution of the air gap and the contact area were investigated for different body postures of a flexible manikin. In addition, the effect of the garment fit (regular and loose) and style (t-shirts, sweatpants, jacket and trousers) were analysed for the interaction between the body postures and the garment properties. A flexible manikin was scanned using a three-dimensional (3D) body scanning technique, and the scans were post-processed in dedicated software. The body posture had a strong effect on the air gap thickness and the contact area for regions where the garment had a certain distance from the body. Furthermore, a mathematical model was proposed to estimate the possible heat transfer coefficient for the observed air layers and their change with posture. The outcome of this study can be used to improve the design of the protective and functional garments and predict their effect on the human body.

Evaluation of the impact of adjusting the angle of the axis of a wind turbine rotor relative to the flow of air stream on operating parameters of a wind turbine model

Directory of Open Access Journals (Sweden)

Gumuła Stanisław

2017-01-01

Full Text Available The aim of this study was to determine the effect of regulation of an axis of a wind turbine rotor to the direction of wind on the volume of energy produced by wind turbines. A role of an optimal setting of the blades of the wind turbine rotor was specified, as well. According to the measurements, changes in the tilt angle of the axis of the wind turbine rotor in relation to the air stream flow direction cause changes in the use of wind energy. The publication explores the effects of the operating conditions of wind turbines on the possibility of using wind energy. A range of factors affect the operation of the wind turbine, and thus the volume of energy produced by the plant. The impact of design parameters of wind power plant, climatic factors or associated with the location seismic challenges can be shown from among them. One of the parameters has proved to be change settings of the rotor axis in relation to direction of flow of the air stream. Studies have shown that the accurate determination of the optimum angle of the axis of the rotor with respect to flow of air stream strongly influences the characteristics of the wind turbine.

Feasibility study of a hybrid wind turbine system – Integration with compressed air energy storage

International Nuclear Information System (INIS)

Sun, Hao; Luo, Xing; Wang, Jihong

2015-01-01

Highlights: • A new hybrid wind turbine system is proposed and feasibility study if conducted. • A complete mathematical model is developed and implemented in a software environment. • Multi-mode control strategy is investigated to ensure the system work smoothly and efficiently. • A prototype for implementing the proposed mechanism is built and tested as proof of the concept. • The proposed system is proved to be technically feasible with energy efficiency around 50%. - Abstract: Wind has been recognized as one of major realistic clean energy sources for power generation to meet the continuously increased energy demand and to achieve the carbon emission reduction targets. However, the utilisation of wind energy encounters an inevitable challenge resulting from the nature of wind intermittency. To address this, the paper presents the recent research work at Warwick on the feasibility study of a new hybrid system by integrating a wind turbine with compressed air energy storage. A mechanical transmission mechanism is designed and implemented for power integration within the hybrid system. A scroll expander is adopted to serve as an “air-machinery energy converter”, which can transmit additional driving power generalized from the stored compressed air to the turbine shaft for smoothing the wind power fluctuation. A mathematical model for the complete hybrid process is developed and the control strategy is investigated for corresponding cooperative operations. A prototype test rig for implementing the proposed mechanism is built for proof of the concept. From the simulated and experimental studies, the energy conversion efficiency analysis is conducted while the system experiences different operation conditions and modes. It is proved that the proposed hybrid wind turbine system is feasible technically

Analysis of vector wind change with respect to time for Vandenberg Air Force Base, California

Science.gov (United States)

Adelfang, S. I.

1978-01-01

A statistical analysis of the temporal variability of wind vectors at 1 km altitude intervals from 0 to 27 km altitude taken from a 10-year data sample of twice-daily rawinsode wind measurements over Vandenberg Air Force Base, California is presented.

An efficient modeling of fine air-gaps in tokamak in-vessel components for electromagnetic analyses

International Nuclear Information System (INIS)

Oh, Dong Keun; Pak, Sunil; Jhang, Hogun

2012-01-01

Highlights: ► A simple and efficient modeling technique is introduced to avoid undesirable massive air mesh which is usually encountered at the modeling of fine structures in tokamak in-vessel component. ► This modeling method is based on the decoupled nodes at the boundary element mocking the air gaps. ► We demonstrated the viability and efficacy, comparing this method with brute force modeling of air-gaps and effective resistivity approximation instead of detail modeling. ► Application of the method to the ITER machine was successfully carried out without sacrificing computational resources and speed. - Abstract: A simple and efficient modeling technique is presented for a proper analysis of complicated eddy current flows in conducting structures with fine air gaps. It is based on the idea of replacing a slit with the decoupled boundary of finite elements. The viability and efficacy of the technique is demonstrated in a simple problem. Application of the method to electromagnetic load analyses during plasma disruptions in ITER has been successfully carried out without sacrificing computational resources and speed. This shows the proposed method is applicable to a practical system with complicated geometrical structures.

The Use of Red Green Blue Air Mass Imagery to Investigate the Role of Stratospheric Air in a Non-convective Wind Event

Science.gov (United States)

Berndt, E. B.; Zavodsky, B. T.; Jedlovec, G. J.; Molthan, A. L.

2013-01-01

Non-convective wind events commonly occur with passing extratropical cyclones and have significant societal and economic impacts. Since non-convective winds often occur in the absence of specific phenomena such as a thunderstorm, tornado, or hurricane, the public are less likely to heed high wind warnings and continue daily activities. Thus non-convective wind events result in as many fatalities as straight line thunderstorm winds. One physical explanation for non-convective winds includes tropopause folds. Improved model representation of stratospheric air and associated non-convective wind events could improve non-convective wind forecasts and associated warnings. In recent years, satellite data assimilation has improved skill in forecasting extratropical cyclones; however errors still remain in forecasting the position and strength of extratropical cyclones as well as the tropopause folding process. The goal of this study is to determine the impact of assimilating satellite temperature and moisture retrieved profiles from hyperspectral infrared (IR) sounders (i.e. Atmospheric Infrared Sounder (AIRS), Cross-track Infrared and Microwave Sounding Suite (CrIMSS), and Infrared Atmospheric Sounding Interferometer (IASI)) on the model representation of the tropopause fold and an associated high wind event that impacted the Northeast United States on 09 February 2013. Model simulations using the Advanced Research Weather Research and Forecasting Model (ARW) were conducted on a 12-km grid with cycled data assimilation mimicking the operational North American Model (NAM). The results from the satellite assimilation run are compared to a control experiment (without hyperspectral IR retrievals), Modern Era-Retrospective Analysis for Research and Applications (MERRA) reanalysis, and Rapid Refresh analyses.

Air-sea dimethylsulfide (DMS) gas transfer in the North Atlantic: evidence for limited interfacial gas exchange at high wind speed

Science.gov (United States)

Bell, T. G.; De Bruyn, W.; Miller, S. D.; Ward, B.; Christensen, K.; Saltzman, E. S.

2013-11-01

Shipboard measurements of eddy covariance dimethylsulfide (DMS) air-sea fluxes and seawater concentration were carried out in the North Atlantic bloom region in June/July 2011. Gas transfer coefficients (k660) show a linear dependence on mean horizontal wind speed at wind speeds up to 11 m s-1. At higher wind speeds the relationship between k660 and wind speed weakens. At high winds, measured DMS fluxes were lower than predicted based on the linear relationship between wind speed and interfacial stress extrapolated from low to intermediate wind speeds. In contrast, the transfer coefficient for sensible heat did not exhibit this effect. The apparent suppression of air-sea gas flux at higher wind speeds appears to be related to sea state, as determined from shipboard wave measurements. These observations are consistent with the idea that long waves suppress near-surface water-side turbulence, and decrease interfacial gas transfer. This effect may be more easily observed for DMS than for less soluble gases, such as CO2, because the air-sea exchange of DMS is controlled by interfacial rather than bubble-mediated gas transfer under high wind speed conditions.

The Matter and Imagery of Air in Eduardo Chillida’s The Comb of the Wind XV

Directory of Open Access Journals (Sweden)

Mei-Hsin Chen

2017-08-01

Full Text Available Eduardo Chillida’s The Comb of the Wind XV, embedded in natural rocks rising from the Cantabrian Ocean in 1977, expresses the artistic potential of air as a material, a metaphor, and as an art-maker. With this sculpture, Chillida opened up the possibility for air itself to show indefinite imageries. Although much has been written about this sculptural group from different perspectives, no study has been systematically undertaken to analyze it regarding the theme of the matter of air, which should be considered the core of the work of art. As Gaston Bachelard stated: ‘Chillida wished the iron [of The Comb of the Wind XV] to show aerial realities.’ Hence, this article seeks to study to what ‘aerial realities’ Chillida might refer, and the relationship between air and his artwork. First, this paper delves into the meanings and functions that air involves in Chillida’s artwork, as well as into how the sculptor embodied his poetic of air and allowed the spectator to perceive his sculptural installation with five senses. Also, the interaction between Chillida’s work and Luis Peña Ganchegui’s architectural installation La Plaza del Tenis is examined under the scope of Martin Heidegger’s notion of place. All these aspects are discussed to help readers realize why the air in natural motion is the foundation of The Comb of the Wind XV, and map the holistic imagery of air that Chillida intended to express.

Earth, Wind and Fire. Natural air conditioning; Earth, Wind and Fire. Natuurlijke airconditioning

Energy Technology Data Exchange (ETDEWEB)

Bronsema, B.

2013-06-07

Starting point for the Earth, Wind and Fire research, of which the sub-concepts of Ventec roof, Climate Cascade and Solar Chimney are an integral part of the (Architectural) building design, are the following hypotheses: (1) An integrated approach of Architecture / Constructions and Climate Design is capable of using the available ambient energy in the form of earth mass, wind, and sun, to condition the air mainly naturally in a building; (2) The sub-concepts can be modeled and validated, in order to be able to reliably support the design process in practice; and (3) The sub-concepts can individually or in combination contribute to the realization of zero energy buildings [Dutch] Airconditioning van gebouwen kan volledig met natuurlijke middelen, zonder mechanische ventilatie. Dat stelt de auteur in zijn proefschrift. Hij wil met vallend water, zon en wind een energiepositief kantoor realiseren. Bronsema is nu op zoek naar een gebouw voor een grootschalige praktijkproef met zijn Earth, Wind and Fire-concept. Het systeem bestaat uit drie hoofdonderdelen: het Ventecdak, de Klimaatcascade en de Zonneschoorsteen. Het Ventecdak zorgt voor aanvoer van verse en afvoer van vuile lucht door gebruikmaking van over- en onderdrukken. Die lucht wordt via de klimaatcascade toegevoerd en via een Zonneschoorsteen afgevoerd. Een mock-up van de Zonneschoorsteen is gerealiseerd als een elf meter hoge toren, die met opgevangen warmte van invallend zonlicht ventilatielucht verwarmt. Het op gang brengen van de luchtstroom gebeurt in de Klimaatcascade. Dit is een bouwkundige schacht waarin van bovenaf waterdruppels worden gesproeid waarmee de lucht kan worden gekoeld of verwarmd.

Air Gaps, Size Effect, and Corner-Turning in Ambient LX-17

Energy Technology Data Exchange (ETDEWEB)

Souers, P C; Hernandez, A; Cabacungen, C; Fried, L; Garza, R; Glaesemann, K; Lauderbach, L; Liao, S; Vitello, P

2007-05-30

Various ambient measurements are presented for LX-17. The size (diameter) effect has been measured with copper and Lucite confinement, where the failure radii are 4.0 and 6.5 mm, respectively. The air well corner-turn has been measured with an LX-07 booster, and the dead-zone results are comparable to the previous TATB-boosted work. Four double cylinders have been fired, and dead zones appear in all cases. The steel-backed samples are faster than the Lucite-backed samples by 0.6 {micro}s. Bare LX-07 and LX-17 of 12.7 mm-radius were fired with air gaps. Long acceptor regions were used to truly determine if detonation occurred or not. The LX-07 crossed at 10 mm with a slight time delay. Steady state LX-17 crossed at 3.5 mm gap but failed to cross at 4.0 mm. LX-17 with a 12.7 mm run after the booster crossed a 1.5 mm gap but failed to cross 2.5 mm. Timing delays were measured where the detonation crossed the gaps. The Tarantula model is introduced as embedded in the Linked Cheetah V4.0 reactive flow code at 4 zones/mm. Tarantula has four pressure regions: off, initiation, failure and detonation. A report card of 25 tests run with the same settings on LX-17 is shown, possibly the most extensive simultaneous calibration yet tried with an explosive. The physical basis of some of the input parameters is considered.

A 20-KW Wind Energy Conversion System (WECS) at the Marine Corps Air Station, Kaneohe, Hawaii.

Science.gov (United States)

1983-01-01

of propellers and that vertical-axis wind turbines would be more efficient. Several turbines such as the Darrieus and gyro-mill, of this type are... wind turbines , wind systems siting, alternate energy systems, remote site power generation. 20 ABSTRACT (Con!,,u,. - r r... .. do I(3 lI - d #,d e...Corps Air Station (MCAS) Kaneohe Bay, Hawaii. The wind turbine generator chosen for the evaluation was a horizontal-axis-propeller- downwind rotor

Wind power - energy from air

International Nuclear Information System (INIS)

Alakangas, E.

1998-01-01

The wind conditions for wind power generation are favourable on the coast, in the archipelagos and in the fell areas of Finland. About 7 MW of wind power has been constructed in Finland, with the investment support of the Ministry of Trade and Industry. In 1995 about 11 GWh were produced by wind energy. A number of wind power plants are under design on the coasts of the Gulf of Finland and the Gulf of Bothnia as well as on the Aaland Islands. The first arctic wind park was constructed in Lapland in September 1996

Modeling of air-gap membrane distillation process: A theoretical and experimental study

KAUST Repository

Alsaadi, Ahmad Salem; Ghaffour, NorEddine; Li, Junde; Gray, Stephen R.; Francis, Lijo; Maab, Husnul; Amy, Gary L.

2013-01-01

A one dimensional (1-D) air gap membrane distillation (AGMD) model for flat sheet type modules has been developed. This model is based on mathematical equations that describe the heat and mass transfer mechanisms of a single-stage AGMD process

Wind Energy Industry Eagle Detection and Deterrents: Research Gaps and Solutions Workshop Summary Report

Energy Technology Data Exchange (ETDEWEB)

Sinclair, Karin [National Renewable Energy Lab. (NREL), Golden, CO (United States); DeGeorge, Elise [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2016-04-13

The Bald and Golden Eagle Protection Act (BGEPA) prohibits the 'take' of these birds. The act defines take as to 'pursue, shoot, shoot at, poison, wound, kill, capture, trap, collect, destroy, molest or disturb.' The 2009 Eagle Permit Rule (74 FR 46836) authorizes the U.S. Fish and Wildlife Service (USFWS) to issue nonpurposeful (i.e., incidental) take permits, and the USFWS 2013 Eagle Conservation Plan Guidance provides a voluntary framework for issuing programmatic take permits to wind facilities that incorporate scientifically supportable advanced conservation practices (ACPs). Under these rules, the Service can issue permits that authorize individual instances of take of bald and golden eagles when the take is associated with, but not the purpose of, an otherwise lawful activity, and cannot practicably be avoided. To date, the USFWS has not approved any ACPs, citing the lack of evidence for 'scientifically supportable measures.' The Eagle Detection and Deterrents Research Gaps and Solutions Workshop was convened at the National Renewable Energy Laboratory in December 2015 with a goal to comprehensively assess the current state of technologies to detect and deter eagles from wind energy sites and the key gaps concerning reducing eagle fatalities and facilitating permitting under the BGEPA. During the workshop, presentations and discussions focused primarily on existing knowledge (and limitations) about the biology of eagles as well as technologies and emerging or novel ideas, including innovative applications of tools developed for use in other sectors, such as the U.S. Department of Defense and aviation. The main activity of the workshop was the breakout sessions, which focused on the current state of detection and deterrent technologies and novel concepts/applications for detecting and minimizing eagle collisions with wind turbines. Following the breakout sessions, participants were asked about their individual impressions of the

Compressed air energy storage system reservoir size for a wind energy baseload power plant

Energy Technology Data Exchange (ETDEWEB)

Cavallo, A.J.

1996-12-31

Wind generated electricity can be transformed from an intermittent to a baseload resource using an oversized wind farm in conjunction with a compressed air energy storage (CAES) system. The size of the storage reservoir for the CAES system (solution mined salt cavern or porous media) as a function of the wind speed autocorrelation time (C) has been examined using a Monte Carlo simulation for a wind class 4 (wind power density 450 W m{sup -2} at 50 m hub height) wind regime with a Weibull k factor of 2.5. For values of C typically found for winds over the US Great Plains, the storage reservoir must have a 60 to 80 hour capacity. Since underground reservoirs account for only a small fraction of total system cost, this larger storage reservoir has a negligible effect on the cost of energy from the wind energy baseload system. 7 refs., 2 figs., 1 tab.

Considerations and Optimization of Time-Resolved PIV Measurements near Complex Wind-Generated Air-Water Wave Interface

Science.gov (United States)

Stegmeir, Matthew; Markfort, Corey

2017-11-01

Time Resolved PIV measurements are applied on both sides of air-water interface in order to study the coupling between air and fluid motion. The multi-scale and 3-dimensional nature of the wave structure poses several unique considerations to generate optimal-quality data very near the fluid interface. High resolution and dynamic range in space and time are required to resolve relevant flow scales along a complex and ever-changing interface. Characterizing the two-way coupling across the air-water interface provide unique challenges for optical measurement techniques. Approaches to obtain near-boundary measurement on both sides of interface are discussed, including optimal flow seeding procedures, illumination, data analysis, and interface tracking. Techniques are applied to the IIHR Boundary-Layer Wind-Wave Tunnel and example results presented for both sides of the interface. The facility combines a 30m long recirculating water channel with an open-return boundary layer wind tunnel, allowing for the study of boundary layer turbulence interacting with a wind-driven wave field.

How well does wind speed predict air-sea gas transfer in the sea ice zone? A synthesis of radon deficit profiles in the upper water column of the Arctic Ocean

Science.gov (United States)

Loose, B.; Kelly, R. P.; Bigdeli, A.; Williams, W.; Krishfield, R.; Rutgers van der Loeff, M.; Moran, S. B.

2017-05-01

We present 34 profiles of radon-deficit from the ice-ocean boundary layer of the Beaufort Sea. Including these 34, there are presently 58 published radon-deficit estimates of air-sea gas transfer velocity (k) in the Arctic Ocean; 52 of these estimates were derived from water covered by 10% sea ice or more. The average value of k collected since 2011 is 4.0 ± 1.2 m d-1. This exceeds the quadratic wind speed prediction of weighted kws = 2.85 m d-1 with mean-weighted wind speed of 6.4 m s-1. We show how ice cover changes the mixed-layer radon budget, and yields an "effective gas transfer velocity." We use these 58 estimates to statistically evaluate the suitability of a wind speed parameterization for k, when the ocean surface is ice covered. Whereas the six profiles taken from the open ocean indicate a statistically good fit to wind speed parameterizations, the same parameterizations could not reproduce k from the sea ice zone. We conclude that techniques for estimating k in the open ocean cannot be similarly applied to determine k in the presence of sea ice. The magnitude of k through gaps in the ice may reach high values as ice cover increases, possibly as a result of focused turbulence dissipation at openings in the free surface. These 58 profiles are presently the most complete set of estimates of k across seasons and variable ice cover; as dissolved tracer budgets they reflect air-sea gas exchange with no impact from air-ice gas exchange.

A Model for Analyzing a Five-Phase Fractional-Slot Permanent Magnet Tubular Linear Motor with Modified Winding Function Approach

Directory of Open Access Journals (Sweden)

Bo Zhang

2016-01-01

Full Text Available This paper presents a model for analyzing a five-phase fractional-slot permanent magnet tubular linear motor (FSPMTLM with the modified winding function approach (MWFA. MWFA is a fast modeling method and it gives deep insight into the calculations of the following parameters: air-gap magnetic field, inductances, flux linkages, and detent force, which are essential in modeling the motor. First, using a magnetic circuit model, the air-gap magnetic density is computed from stator magnetomotive force (MMF, flux barrier, and mover geometry. Second, the inductances, flux linkages, and detent force are analytically calculated using modified winding function and the air-gap magnetic density. Finally, a model has been established with the five-phase Park transformation and simulated. The calculations of detent force reveal that the end-effect force is the main component of the detent force. This is also proven by finite element analysis on the motor. The accuracy of the model is validated by comparing with the results obtained using semianalytical method (SAM and measurements to analyze the motor’s transient characteristics. In addition, the proposed method requires less computation time.

Capabilities and Gaps Assessments of Urban Air Quality Manage-ment in Uganda

Directory of Open Access Journals (Sweden)

Amin Tamale Kiggundu

2015-06-01

Full Text Available Today, large cities across the globe are facing a pervasive problem of air pollution.  The purpose of this study is to assess the capabilities and gaps in urban air quality management in Uganda as well as proposing strategies for curbing air pollution. This study applied face to face interviews, targeting key informants such as the environmental experts, urbanization researchers and officials from the National Environment Management Authority (NEMA. Results show that rapid motorization, continued dependence on fossil fuels, open waste burning, biomass burning, industrialization, bushfires and urbanization are the key causes of air pollution in Uganda. To reduce air pollution and improve urban air quality it is critical to promote non-motorised mass transport, increase electricity access, regulate open waste burning, establish laboratories, strengthen local research and training capacity, promote collaborations, introduce more fuel efficient vehicles and periodic vehicle inspection and carry out public awareness campaigns about air pollution.

AIR FLOW AND ENVIRONMENTAL WIND VISUALIZATION USING A CW DIODE PUMPED FREQUENCY DOUBLED Nd:YAG Laser

Directory of Open Access Journals (Sweden)

Mircea UDREA

2009-09-01

Full Text Available Preliminary results obtained in developing a visualisation technique for non-invasive analysis of air flow inside INCAS subsonic wind tunnel and its appendages are presented. The visualisation technique is based on using a green light sheet generated by a continuous wave (cw longitudinally diode pumped and frequency doubled Nd:YAG laser. The output laser beam is expanded on one direction and collimated on rectangular direction. The system is tailored to the requirements of qualitative analysis and vortex tracking requirements inside the INCAS 2.5m x 2.0m subsonic wind tunnel test section, for measurements performed on aircraft models. Also the developed laser techniques is used for non-invasive air flow field analysis into environmental facilities settling room (air flow calming area. Quantitative analysis is enabled using special image processing tools upon movies and pictures obtained during the experiments. The basic experimental layout in the wind tunnel takes advantage of information obtained from the investigation of various aircraft models using the developed visualisation technique. These results are further developed using a Particle Imaging Velocimetry (PIV experimental technique.The focus is on visualisation techniques to be used for wind flow characterization at different altitudes in indus-trial and civil buildings areas using a light sheet generated by a Nd:YAG cw pumped and doubled laser at 532 nm wave-length. The results are important for prevention of biological/chemical disasters such as spreading of extremely toxic pol-lutants due to wind. Numerical simulations of wind flow and experimental visualisation results are compared. A good agreement between these results is observed.

Economics of compressed air energy storage to integrate wind power: A case study in ERCOT

Energy Technology Data Exchange (ETDEWEB)

Fertig, Emily, E-mail: efertig@andrew.cmu.ed [Carnegie Mellon Electricity Industry Center, Department of Engineering and Public Policy and Tepper School of Business, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States); Apt, Jay [Carnegie Mellon Electricity Industry Center, Department of Engineering and Public Policy and Tepper School of Business, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States)

2011-05-15

Compressed air energy storage (CAES) could be paired with a wind farm to provide firm, dispatchable baseload power, or serve as a peaking plant and capture upswings in electricity prices. We present a firm-level engineering-economic analysis of a wind/CAES system with a wind farm in central Texas, load in either Dallas or Houston, and a CAES plant whose location is profit-optimized. With 2008 hourly prices and load in Houston, the economically optimal CAES expander capacity is unrealistically large - 24 GW - and dispatches for only a few hours per week when prices are highest; a price cap and capacity payment likewise results in a large (17 GW) profit-maximizing CAES expander. Under all other scenarios considered the CAES plant is unprofitable. Using 2008 data, a baseload wind/CAES system is less profitable than a natural gas combined cycle (NGCC) plant at carbon prices less than $56/tCO{sub 2} ($15/MMBTU gas) to $230/tCO{sub 2} ($5/MMBTU gas). Entering regulation markets raises profit only slightly. Social benefits of CAES paired with wind include avoided construction of new generation capacity, improved air quality during peak times, and increased economic surplus, but may not outweigh the private cost of the CAES system nor justify a subsidy. - Research highlights: {yields} Sizes of CAES and transmission paired with a Texas wind farm are optimized for profit. {yields} A profit-maximizing wind farm owner would not invest in a dedicated CAES system. {yields} The social benefit of a wind/CAES system is unlikely to outweigh private cost. {yields} CAES cannot cost-effectively smooth wind power with plausible imminent carbon prices.

Economics of compressed air energy storage to integrate wind power: A case study in ERCOT

International Nuclear Information System (INIS)

Fertig, Emily; Apt, Jay

2011-01-01

Compressed air energy storage (CAES) could be paired with a wind farm to provide firm, dispatchable baseload power, or serve as a peaking plant and capture upswings in electricity prices. We present a firm-level engineering-economic analysis of a wind/CAES system with a wind farm in central Texas, load in either Dallas or Houston, and a CAES plant whose location is profit-optimized. With 2008 hourly prices and load in Houston, the economically optimal CAES expander capacity is unrealistically large - 24 GW - and dispatches for only a few hours per week when prices are highest; a price cap and capacity payment likewise results in a large (17 GW) profit-maximizing CAES expander. Under all other scenarios considered the CAES plant is unprofitable. Using 2008 data, a baseload wind/CAES system is less profitable than a natural gas combined cycle (NGCC) plant at carbon prices less than $56/tCO 2 ($15/MMBTU gas) to $230/tCO 2 ($5/MMBTU gas). Entering regulation markets raises profit only slightly. Social benefits of CAES paired with wind include avoided construction of new generation capacity, improved air quality during peak times, and increased economic surplus, but may not outweigh the private cost of the CAES system nor justify a subsidy. - Research highlights: → Sizes of CAES and transmission paired with a Texas wind farm are optimized for profit. → A profit-maximizing wind farm owner would not invest in a dedicated CAES system. → The social benefit of a wind/CAES system is unlikely to outweigh private cost. → CAES cannot cost-effectively smooth wind power with plausible imminent carbon prices.

Heat Transfer Enhancement of the Air-Cooling Tower with Rotating Wind Deflectors under Crosswind Conditions

OpenAIRE

Xueping Du; Dongtai Han; Qiangmin Zhu

2018-01-01

To investigate the effect of wind deflectors on air flow and heat transfer performance of an air-cooling tower under crosswind conditions, an experimental system based on a surface condenser aluminum exchanger-type indirect air-cooling tower is established at a 1:100 proportional reduction. A 3-D computational fluid dynamics simulation model is built to study the air flow and temperature fields. The air flow rate into the cooling tower and the heat transfer rate of the radiators are used to e...

Clear air boundary layer spaced antenna wind measurement with the Multiple Antenna Profiler (MAPR

Directory of Open Access Journals (Sweden)

S. A. Cohn

Full Text Available Spaced antenna (SA wind measurement techniques are applied to Multiple Antenna Profiler (MAPR data to evaluate its performance in clear air conditions. MAPR is a multiple antenna 915 MHz wind profiler developed at the National Center for Atmospheric Research (NCAR and described in Cohn et al. (1997, designed to make high resolution wind measurements. Previous reported measurements with MAPR were restricted to precipitation because of low signal to noise (SNR and signal to ground-clutter (SCR ratios. By using a standard pulse-coding technique and upgrading the profiler control software, increases in average power and SNR were achieved, making routine measurements in clear air possible. Comparison of winds measured by MAPR and by a sonic anemometer on a nearby 300 m tower show correlation coefficients in the range of R² = 0.75 – 0.80, and an average absolute error of ~ 1.4 m s - 1 . This compares favorably with the agreement typically found in wind profiler comparisons. We also consider the use of the parameter ah , which is related to the value of the cross-correlation function at its zero crossing. This parameter is a data quality indicator and possibly a key component in a ground clutter removal technique.

Key words. Meteorology and atmospheric dynamics (mesoscale meteorology; instruments and techniques – Radio science (remote sensing

Zonal surface wind jets across the Red Sea due to mountain gap forcing along both sides of the Red Sea

KAUST Repository

Jiang, Houshuo; Farrar, J. Thomas; Beardsley, Robert C.; Chen, Ru; Chen, Changsheng

2009-01-01

[1] Mesoscale atmospheric modeling over the Red Sea, validated by in-situ meteorological buoy data, identifies two types of coastal mountain gap wind jets that frequently blow across the longitudinal axis of the Red Sea: (1) an eastward

Design and Experimental Analysis of an Exhaust Air Energy Recovery Wind Turbine Generator

Directory of Open Access Journals (Sweden)

Ahmad Fazlizan

2015-06-01

Full Text Available A vertical axis wind turbine (VAWT was positioned at the discharge outlet of a cooling tower electricity generator. To avoid a negative impact on the performance of the cooling tower and to optimize the turbine performance, the determination of the VAWT position in the discharge wind stream was conducted by experiment. The preferable VAWT position is where the higher wind velocity matches the positive torque area of the turbine rotation. With the proper matching among the VAWT configurations (blade number, airfoil type, operating tip-speed-ratio, etc. and exhaust air profile, the turbine system was not only able to recover the wasted kinetic energy, it also reduced the fan motor power consumption by 4.5% and increased the cooling tower intake air flow-rate by 11%. The VAWT had a free running rotational speed of 479 rpm, power coefficient of 10.6%, and tip-speed-ratio of 1.88. The double multiple stream tube theory was used to explain the VAWT behavior in the non-uniform wind stream. For the actual size of a cooling tower with a 2.4 m outlet diameter and powered by a 7.5 kW fan motor, it was estimated that a system with two VAWTs (side-by-side can generate 1 kW of power which is equivalent to 13% of energy recovery.

Piezoelectric transformers for low-voltage generation of gas discharges and ionic winds in atmospheric air

Energy Technology Data Exchange (ETDEWEB)

Johnson, Michael J. [Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, Indianapolis 46556 (United States); Go, David B., E-mail: dgo@nd.edu [Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, Indianapolis 46556 (United States); Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indianapolis 46556 (United States)

2015-12-28

To generate a gas discharge (plasma) in atmospheric air requires an electric field that exceeds the breakdown threshold of ∼30 kV/cm. Because of safety, size, or cost constraints, the large applied voltages required to generate such fields are often prohibitive for portable applications. In this work, piezoelectric transformers are used to amplify a low input applied voltage (<30 V) to generate breakdown in air without the need for conventional high-voltage electrical equipment. Piezoelectric transformers (PTs) use their inherent electromechanical resonance to produce a voltage amplification, such that the surface of the piezoelectric exhibits a large surface voltage that can generate corona-like discharges on its corners or on adjacent electrodes. In the proper configuration, these discharges can be used to generate a bulk air flow called an ionic wind. In this work, PT-driven discharges are characterized by measuring the discharge current and the velocity of the induced ionic wind with ionic winds generated using input voltages as low as 7 V. The characteristics of the discharge change as the input voltage increases; this modifies the resonance of the system and subsequent required operating parameters.

The response of the Red Sea to a strong wind jet near the Tokar Gap in summer

KAUST Repository

Zhai, Ping

2013-01-01

[1] Remote sensing and in situ observations are used to investigate the ocean response to the Tokar Wind Jet in the Red Sea. The wind jet blows down the atmospheric pressure gradient through the Tokar Gap on the Sudanese coast, at about 19°N, during the summer monsoon season. It disturbs the prevailing along-sea (southeastward) winds with strong cross-sea (northeastward) winds that can last from days to weeks and reach amplitudes of 20-25 m/s. By comparing scatterometer winds with along-track and gridded sea level anomaly observations, it is observed that an intense dipolar eddy spins up in response to the wind jet. The eddy pair has a horizontal scale of 140 km. Maximum ocean surface velocities can reach 1 m/s and eddy currents extend more than 100 m into the water column. The eddy currents appear to cover the width of the sea, providing a pathway for rapid transport of marine organisms and other drifting material from one coast to the other. Interannual variability in the strength of the dipole is closely matched with variability in the strength of the wind jet. The dipole is observed to be quasi-stationary, although there is some evidence for slow eastward propagation in an idealized numerical model. Simulation of the dipole in an idealized high-resolution numerical model suggests that this is the result of self-advection. © 2012. American Geophysical Union. All Rights Reserved.

Computational and experimental optimization of the exhaust air energy recovery wind turbine generator

International Nuclear Information System (INIS)

Tabatabaeikia, Seyedsaeed; Ghazali, Nik Nazri Bin Nik; Chong, Wen Tong; Shahizare, Behzad; Izadyar, Nima; Esmaeilzadeh, Alireza; Fazlizan, Ahmad

2016-01-01

Highlights: • Studying the viability of harvesting wasted energy by exhaust air recovery generator. • Optimizing the design using response surface methodology. • Validation of optimization and computation result by performing experimental tests. • Investigation of flow behaviour using computational fluid dynamic simulations. • Performing the technical and economic study of the exhaust air recovery generator. - Abstract: This paper studies the optimization of an innovative exhaust air recovery wind turbine generator through computational fluid dynamic (CFD) simulations. The optimization strategy aims to optimize the overall system energy generation and simultaneously guarantee that it does not violate the cooling tower performance in terms of decreasing airflow intake and increasing fan motor power consumption. The wind turbine rotor position, modifying diffuser plates, and introducing separator plates to the design are considered as the variable factors for the optimization. The generated power coefficient is selected as optimization objective. Unlike most of previous optimizations in field of wind turbines, in this study, response surface methodology (RSM) as a method of analytical procedures optimization has been utilised by using multivariate statistic techniques. A comprehensive study on CFD parameters including the mesh resolution, the turbulence model and transient time step values is presented. The system is simulated using SST K-ω turbulence model and then both computational and optimization results are validated by experimental data obtained in laboratory. Results show that the optimization strategy can improve the wind turbine generated power by 48.6% compared to baseline design. Meanwhile, it is able to enhance the fan intake airflow rate and decrease fan motor power consumption. The obtained optimization equations are also validated by both CFD and experimental results and a negligible deviation in range of 6–8.5% is observed.

Effect of heterogenous and homogenous air gaps on dry heat loss through the garment

Science.gov (United States)

Mert, Emel; Psikuta, Agnes; Bueno, Marie-Ange; Rossi, René M.

2015-11-01

In real life conditions, the trapped air between the human body and the garment has uneven shape and vary over the body parts as a consequence of the complex geometry of the human body. However, the existing clothing models assume uniform air layer between the human body and the garment or its full contact, which may cause large error in the output of simulations. Therefore, the aim of this study was to investigate the effect of a heterogeneous vertical air gap with different configuration of folds (size and frequency) on dry heat loss using a heated cylinder (Torso). It was found that the presence of folds in the garment led to an increased heat loss from the body in comparison to a homogeneous air gap of comparable size. Interestingly, the size of folds did not have an influence on the dry heat loss. Additionally, the effect of the contact area on dry heat loss became important when exceeding a threshold of about 42 %. The results from this study are useful for modelling of a realistic dry heat loss through the clothing and contribute to the improvement of design of protective and active sport garments.

Mechanism of air-sea momentum flux from low to high winds

Science.gov (United States)

Zhao, Dongliang

2017-04-01

In the condition of wind speed less than 20 m/s, many studies have shown that drag coefficient roughly increases linearly with wind speed, which is usually extrapolated to high winds in practice. Since the pioneer work of Powell et al. (2003), both field and laboratory studies have indicated that the drag coefficient begins to decrease or saturate when wind speed is greater than a critical value such as 30 m/s. All the reduction mechanisms proposed up to now are related to the effect of sea spray induced by wave breaking in high winds. This study tries to propose another mechanism that is directly related to wave breaking. Based on the wind-wave growth relations, it is found that drag coefficient increases simultaneously with wave age and wave steepness. The reduction of drag coefficient with wave age that has been shown by previous studies mainly reflect the wind effect because the phase speeds of waves vary in a very narrow range, and can be roughly regarded as constant. It is indicated that two parameters including wave age and wave steepness together control the momentum transfer through air-sea interface. The wave age and wave steepness represent the abilities of wind input and wave receiving energy, respectively. In general, the two parameters are well correlated and can be replaced one another in the condition of low and moderate winds, in which the wave steepness decreases with the increasing wave age. In the condition of high winds, the wave steepness reaches to its upper threshold due to wave breaking, in which wave steepness cannot increase with the decreasing of wave age. At the same time, wave ages become very small, thus drag coefficients begin to decrease with wind speed. It is further suggested that there are two different upper thresholds of wave steepness for laboratory and field waves, which can be applied to explain the reduction of drag coefficient either in laboratory or in field

High efficient OLED displays prepared with the air-gapped bridges on quantum dot patterns for optical recycling

Science.gov (United States)

Kim, Hyo-Jun; Shin, Min-Ho; Kim, Joo-Suc; Kim, Se-Eun; Kim, Young-Joo

2017-02-01

An optically efficient structure was proposed and fabricated to realize high brightness organic light emitting diode (OLED) displays based on a white OLED prepared with the air-gapped bridges on the quantum dot (QD) patterns. Compared with a conventional white OLED display, in our experiments, the optical intensity of the proposed OLED display shows the enhancement of 58.2% in the red color and 16.8% in the green color after applying the air-gapped bridge structure on QD patterns of 20 wt% concentration. This enhancement comes from the two facts that the QD patterns downconvert unnecessary blue or blue/green light to the required green or red light and the air-gapped bridges increase the color conversion efficiency of QDs by optical recycling using total internal reflection (TIR) at the interface. In addition, the color gamut of the proposed OLED display increases from 65.5 to 75.9% (NTSC x, y ratio) due to the narrow emission spectra of QDs.

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.

Heat Transfer Coefficient at Cast-Mold Interface During Centrifugal Casting: Calculation of Air Gap

Science.gov (United States)

Bohacek, Jan; Kharicha, Abdellah; Ludwig, Andreas; Wu, Menghuai; Karimi-Sibaki, Ebrahim

2018-06-01

During centrifugal casting, the thermal resistance at the cast-mold interface represents a main blockage mechanism for heat transfer. In addition to the refractory coating, an air gap begins to form due to the shrinkage of the casting and the mold expansion, under the continuous influence of strong centrifugal forces. Here, the heat transfer coefficient at the cast-mold interface h has been determined from calculations of the air gap thickness d a based on a plane stress model taking into account thermoelastic stresses, centrifugal forces, plastic deformations, and a temperature-dependent Young's modulus. The numerical approach proposed here is rather novel and tries to offer an alternative to the empirical formulas usually used in numerical simulations for a description of a time-dependent heat transfer coefficient h. Several numerical tests were performed for different coating thicknesses d C, rotation rates Ω, and temperatures of solidus T sol. Results demonstrated that the scenario at the interface is unique for each set of parameters, hindering the possibility of employing empirical formulas without a preceding experiment being performed. Initial values of h are simply equivalent to the ratio of the coating thermal conductivity and its thickness ( 1000 Wm-2 K-1). Later, when the air gap is formed, h drops exponentially to values at least one order of magnitude smaller ( 100 Wm-2 K-1).

Wind Regimes in Complex Terrain of the Great Valley of Eastern Tennessee

Energy Technology Data Exchange (ETDEWEB)

Birdwell, Kevin R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2011-05-01

flowed on-axis only 40% of the time. The Great Smoky Mountains helped create down-valley pressure-driven winds, downslope mountain breezes, and divergent air flow. The Cumberland Mountains and Plateau were associated with wind speed reductions in the Central Great Valley, Emory Gap Flow, weak thermally-driven winds, and northwesterly down sloping. Ridge-and-valley terrain enhanced wind direction reversals, pressure-driven winds, as well as locally and regionally produced thermally-driven flow.

Air gap membrane distillation. 2. Model validation and hollow fibre module performance analysis

NARCIS (Netherlands)

Guijt, C.M.; Meindersma, G.W.; Reith, T.; de Haan, A.B.

2005-01-01

In this paper the experimental results of counter current flow air gap membrane distillation experiments are presented and compared with predictive model calculations. Measurements were carried out with a cylindrical test module containing a single hollow fibre membrane in the centre and a

High efficient OLED displays prepared with the air-gapped bridges on quantum dot patterns for optical recycling

OpenAIRE

Hyo-Jun Kim; Min-Ho Shin; Joo-Suc Kim; Se-Eun Kim; Young-Joo Kim

2017-01-01

An optically efficient structure was proposed and fabricated to realize high brightness organic light emitting diode (OLED) displays based on a white OLED prepared with the air-gapped bridges on the quantum dot (QD) patterns. Compared with a conventional white OLED display, in our experiments, the optical intensity of the proposed OLED display shows the enhancement of 58.2% in the red color and 16.8% in the green color after applying the air-gapped bridge structure on QD patterns of 20?wt% co...

Large superconducting wind turbine generators

DEFF Research Database (Denmark)

Abrahamsen, Asger Bech; Magnusson, Niklas; Jensen, Bogi Bech

2012-01-01

and the rotation speed is lowered in order to limit the tip speed of the blades. The ability of superconducting materials to carry high current densities with very small losses might facilitate a new class of generators operating with an air gap flux density considerably higher than conventional generators...... and thereby having a smaller size and weight [1, 2]. A 5 MW superconducting wind turbine generator forms the basics for the feasibility considerations, particularly for the YBCO and MgB2 superconductors entering the commercial market. Initial results indicate that a 5 MW generator with an active weight of 34...

Impulse breakdown of small air gap in electric field Part II: Statistical ...

African Journals Online (AJOL)

The patterns of shot distribution and maximum coverage at impulse breakdown voltage for positive point electr-odes (needle and cone electrodes) in small air gaps in non-uniform electric fields were investigated. During the breakdown test, a sheet of paper was placed on the plate electrode (-ve), and each breakdown shot ...

Bremsstrahlung of fast electrons in long air gaps

Energy Technology Data Exchange (ETDEWEB)

Oreshkin, E. V.; Barengolts, S. A. [P. N. Lebedev Physical Institute, RAS, 119991 Moscow (Russian Federation); General Physics Institute, RAS, 119991 Moscow (Russian Federation); Chaikovsky, S. A. [P. N. Lebedev Physical Institute, RAS, 119991 Moscow (Russian Federation); Institute of High Current Electronics, SB RAS, 634055 Tomsk (Russian Federation); Oginov, A. V.; Shpakov, K. V.; Bogachenkov, V. A. [P. N. Lebedev Physical Institute, RAS, 119991 Moscow (Russian Federation)

2012-01-15

The results of an experiment on discharges in long atmospheric pressure air gaps at a pulsed voltage of amplitude up to 800 kV and risetime 150-200 ns have been analyzed. In the experiment, a radiation pulse of photon energy >5 keV and duration 10-20 ns was observed. In analyzing the experimental data it was supposed that a streamer is a plasma protrusion whose surface is equipotential to the cathode surface. It has been shown that the x-ray pulse results from the switch of electrons into the mode of ''runaway'' from the head of anode-directed streamers. For the electrons injected in the electrode gap from the streamer head, conditions for their switching into the mode of continuous acceleration are realized due to the enhanced electric field at the head. The predicted maximum of the spectrum of the bremsstrahlung generated by the runaway electron beam is around 15 keV. The presence of a maximum in the bremsstrahlung spectrum is due to that the photons emitted by electrons are absorbed by atoms of the gas in which the discharge operate.

Incorporating wind availability into land use regression modelling of air quality in mountainous high-density urban environment.

Science.gov (United States)

Shi, Yuan; Lau, Kevin Ka-Lun; Ng, Edward

2017-08-01

Urban air quality serves as an important function of the quality of urban life. Land use regression (LUR) modelling of air quality is essential for conducting health impacts assessment but more challenging in mountainous high-density urban scenario due to the complexities of the urban environment. In this study, a total of 21 LUR models are developed for seven kinds of air pollutants (gaseous air pollutants CO, NO 2 , NO x , O 3 , SO 2 and particulate air pollutants PM 2.5 , PM 10 ) with reference to three different time periods (summertime, wintertime and annual average of 5-year long-term hourly monitoring data from local air quality monitoring network) in Hong Kong. Under the mountainous high-density urban scenario, we improved the traditional LUR modelling method by incorporating wind availability information into LUR modelling based on surface geomorphometrical analysis. As a result, 269 independent variables were examined to develop the LUR models by using the "ADDRESS" independent variable selection method and stepwise multiple linear regression (MLR). Cross validation has been performed for each resultant model. The results show that wind-related variables are included in most of the resultant models as statistically significant independent variables. Compared with the traditional method, a maximum increase of 20% was achieved in the prediction performance of annual averaged NO 2 concentration level by incorporating wind-related variables into LUR model development. Copyright © 2017 Elsevier Inc. All rights reserved.

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.

Index Bioclimatic "Wind-Chill"

Directory of Open Access Journals (Sweden)

Teodoreanu Elena

2015-05-01

Full Text Available This paper presents an important bioclimatic index which shows the influence of wind on the human body thermoregulation. When the air temperature is high, the wind increases thermal comfort. But more important for the body is the wind when the air temperature is low. When the air temperature is lower and wind speed higher, the human body is threatening to freeze faster. Cold wind index is used in Canada, USA, Russia (temperature "equivalent" to the facial skin etc., in the weather forecast every day in the cold season. The index can be used and for bioclimatic regionalization, in the form of skin temperature index.

Forests under climate change and air pollution: gaps in understanding and future directions for research.

Science.gov (United States)

Matyssek, R; Wieser, G; Calfapietra, C; de Vries, W; Dizengremel, P; Ernst, D; Jolivet, Y; Mikkelsen, T N; Mohren, G M J; Le Thiec, D; Tuovinen, J-P; Weatherall, A; Paoletti, E

2012-01-01

Forests in Europe face significant changes in climate, which in interaction with air quality changes, may significantly affect forest productivity, stand composition and carbon sequestration in both vegetation and soils. Identified knowledge gaps and research needs include: (i) interaction between changes in air quality (trace gas concentrations), climate and other site factors on forest ecosystem response, (ii) significance of biotic processes in system response, (iii) tools for mechanistic and diagnostic understanding and upscaling, and (iv) the need for unifying modelling and empirical research for synthesis. This position paper highlights the above focuses, including the global dimension of air pollution as part of climate change and the need for knowledge transfer to enable reliable risk assessment. A new type of research site in forest ecosystems ("supersites") will be conducive to addressing these gaps by enabling integration of experimentation and modelling within the soil-plant-atmosphere interface, as well as further model development. Copyright © 2011 Elsevier Ltd. All rights reserved.

Spatial discretization methods for air gap permeance calculations in double salient traction motors

NARCIS (Netherlands)

Ilhan, E.; Kremers, M.F.J.; Motoasca, T.E.; Paulides, J.J.H.; Lomonova, E.

2012-01-01

Weight limitations in electric/hybrid cars demand the highest possible power-to-weight ratio from the traction motor, as in double salient permanent magnet (PM) machines. Their high flux densities in the air gap result in nonlinear analytical models, which need to be time optimized. The incorporated

Pneumatic hybridization of a diesel engine using compressed air storage for wind-diesel energy generation

International Nuclear Information System (INIS)

Basbous, Tammam; Younes, Rafic; Ilinca, Adrian; Perron, Jean

2012-01-01

In this paper, we are studying an innovative solution to reduce fuel consumption and production cost for electricity production by Diesel generators. The solution is particularly suitable for remote areas where the cost of energy is very high not only because of inherent cost of technology but also due to transportation costs. It has significant environmental benefits as the use of fossil fuels for electricity generation is a significant source of GHG (Greenhouse Gas) emissions. The use of hybrid systems that combine renewable sources, especially wind, and Diesel generators, reduces fuel consumption and operation cost and has environmental benefits. Adding a storage element to the hybrid system increases the penetration level of the renewable sources, that is the percentage of renewable energy in the overall production, and further improves fuel savings. In a previous work, we demonstrated that CAES (Compressed Air Energy Storage) has numerous advantages for hybrid wind-diesel systems due to its low cost, high power density and reliability. The pneumatic hybridization of the Diesel engine consists to introduce the CAES through the admission valve. We have proven that we can improve the combustion efficiency and therefore the fuel consumption by optimizing Air/Fuel ratio thanks to the CAES assistance. As a continuation of these previous analyses, we studied the effect of the intake pressure and temperature and the exhaust pressure on the thermodynamic cycle of the diesel engine and determined the values of these parameters that will optimize fuel consumption. -- Highlights: ► Fuel economy analysis of a simple pneumatic hybridization of the Diesel engine using stored compressed air. ► Thermodynamic analysis of the pneumatic hybridization of diesel engines for hybrid wind-diesel energy systems. ► Analysis of intake pressure and temperature of compressed air and exhaust pressure on pressure/temperature during Diesel thermodynamic cycle. ► Direct admission of

Inversion Build-Up and Cold-Air Outflow in a Small Alpine Sinkhole

Science.gov (United States)

Lehner, Manuela; Whiteman, C. David; Dorninger, Manfred

2017-06-01

Semi-idealized model simulations are made of the nocturnal cold-air pool development in the approximately 1-km wide and 100-200-m deep Grünloch basin, Austria. The simulations show qualitatively good agreement with vertical temperature and wind profiles and surface measurements collected during a meteorological field expedition. A two-layer stable atmosphere forms in the basin, with a very strong inversion in the lowest part, below the approximate height of the lowest gap in the surrounding orography. The upper part of the stable layer is less strongly stratified and extends to the approximate height of the second-lowest gap. The basin atmosphere cools most strongly during the first few hours of the night, after which temperatures decrease only slowly. An outflow of air forms through the lowest gap in the surrounding orography. The outflow connects with a weak inflow of air through a gap on the opposite sidewall, forming a vertically and horizontally confined jet over the basin. Basin cooling shows strong sensitivity to surface-layer characteristics, highlighting the large impact of variations in vegetation and soil cover on cold-air pool development, as well as the importance of surface-layer parametrization in numerical simulations of cold-air-pool development.

Bearing failure detection of micro wind turbine via power spectral density analysis for stator current signals spectrum

Science.gov (United States)

Mahmood, Faleh H.; Kadhim, Hussein T.; Resen, Ali K.; Shaban, Auday H.

2018-05-01

The failure such as air gap weirdness, rubbing, and scrapping between stator and rotor generator arise unavoidably and may cause extremely terrible results for a wind turbine. Therefore, we should pay more attention to detect and identify its cause-bearing failure in wind turbine to improve the operational reliability. The current paper tends to use of power spectral density analysis method of detecting internal race and external race bearing failure in micro wind turbine by estimation stator current signal of the generator. The failure detector method shows that it is well suited and effective for bearing failure detection.

Vandenberg Air Force Base Upper Level Wind Launch Weather Constraints

Science.gov (United States)

Shafer, Jaclyn A.; Wheeler, Mark M.

2012-01-01

The 30th Operational Support Squadron Weather Flight (30 OSSWF) provides comprehensive weather services to the space program at Vandenberg Air Force Base (VAFB) in California. One of their responsibilities is to monitor upper-level winds to ensure safe launch operations of the Minuteman III ballistic missile. The 30 OSSWF tasked the Applied Meteorology Unit (AMU) to analyze VAFB sounding data with the goal of determining the probability of violating (PoV) their upper-level thresholds for wind speed and shear constraints specific to this launch vehicle, and to develop a tool that will calculate the PoV of each constraint on the day of launch. In order to calculate the probability of exceeding each constraint, the AMU collected and analyzed historical data from VAFB. The historical sounding data were retrieved from the National Oceanic and Atmospheric Administration Earth System Research Laboratory archive for the years 1994-2011 and then stratified into four sub-seasons: January-March, April-June, July-September, and October-December. The maximum wind speed and 1000-ft shear values for each sounding in each subseason were determined. To accurately calculate the PoV, the AMU determined the theoretical distributions that best fit the maximum wind speed and maximum shear datasets. Ultimately it was discovered that the maximum wind speeds follow a Gaussian distribution while the maximum shear values follow a lognormal distribution. These results were applied when calculating the averages and standard deviations needed for the historical and real-time PoV calculations. In addition to the requirements outlined in the original task plan, the AMU also included forecast sounding data from the Rapid Refresh model. This information provides further insight for the launch weather officers (LWOs) when determining if a wind constraint violation will occur over the next few hours on day of launch. The interactive graphical user interface (GUI) for this project was developed in

Modeling and analysis of mover gaps in tubular moving-magnet linear oscillating motors

Directory of Open Access Journals (Sweden)

Xuesong LUO

2018-05-01

Full Text Available A tubular moving-magnet linear oscillating motor (TMMLOM has merits of high efficiency and excellent dynamic capability. To enhance the thrust performance, quasi-Halbach permanent magnet (PM arrays are arranged on its mover in the application of a linear electro-hydrostatic actuator in more electric aircraft. The arrays are assembled by several individual segments, which lead to gaps between them inevitably. To investigate the effects of the gaps on the radial magnetic flux density and the machine thrust in this paper, an analytical model is built considering both axial and radial gaps. The model is validated by finite element simulations and experimental results. Distributions of the magnetic flux are described in condition of different sizes of radial and axial gaps. Besides, the output force is also discussed in normal and end windings. Finally, the model has demonstrated that both kinds of gaps have a negative effect on the thrust, and the linear motor is more sensitive to radial ones. Keywords: Air-gap flux density, Linear motor, Mover gaps, Quasi-Halbach array, Thrust output, Tubular moving-magnet linear oscillating motor (TMMLOM

A decision support tool for evaluating the air quality and wind comfort induced by different opening configurations for buildings in canyons.

Science.gov (United States)

Fan, M; Chau, C K; Chan, E H W; Jia, J

2017-01-01

This study formulated a new index for evaluating both the air quality and wind comfort induced by building openings at the pedestrian level of street canyons. The air pollutant concentrations and wind velocities induced by building openings were predicted by a series of CFD simulations using ANSYS Fluent software based on standard k-ɛ model. The types of opening configurations investigated inside isolated and non-isolated canyons included separations, voids and permeable elements. It was found that openings with permeability values of 10% were adequate for improving the air quality and wind comfort conditions for pedestrians after considering the reduction in development floor areas. Openings were effective in improving the air quality in isolated canyons and different types of opening configurations were suggested for different street aspect ratios. On the contrary, openings were not always found effective for non-isolated canyons if there were pollutant sources in adjacent street canyons. As such, it would also be recommended introducing openings to adjacent canyons along with openings to the target canyons. The formulated index can help city planners and building designers to strike an optimal balance between air quality and wind comfort for pedestrians when designing and planning buildings inside urban streets and thus promoting urban environmental sustainability. Copyright © 2016 Elsevier B.V. All rights reserved.

Effects of air psychrometrics on the exergetic efficiency of a wind farm at a coastal mountainous site – An experimental study

DEFF Research Database (Denmark)

Xydis, George

2012-01-01

In this paper, the most important energy and exergy characteristics of wind energy were examined. Atmospheric variables as air temperature, humidity and pressure and their effects on the wind turbine output were investigated toward wind energy exploitation. It was shown that these usually...

Influence of wind velocity fluctuation on air temperature difference between the fan and ground levels and the effect of frost protective fan operation

International Nuclear Information System (INIS)

Araki, T.; Matsuo, K.; Miyama, D.; Sumikawa, O.; Araki, S.

2008-01-01

We invested the influence of wind velocity fluctuation on air temperature difference between the fan (4.8 m) and ground levels (0.5 m) and the effect of frost protective fan operation in order to develop a new method to reduce electricity consumption due to frost protective fan operation. The results of the investigations are summarized as follows: (1) Air temperature difference between the fan (4.8 m) and ground levels (0.5 m) was decreased following an increase in wind velocity, and the difference was less than 1°C for a wind velocity more than 3.0 m/s at a height of 6.5 m. (2) When the wind velocity was more than 2-3 m/s, there was hardly any increase in the temperature of the leaves. In contrast, when the wind velocity was less than 2-3 m/s, an increase in the temperature of the leaves was observed. Based on these results, it is possible that when the wind velocity is greater than 2-3 m, it prevents thermal inversion. Therefore, there would be no warmer air for the frost protective fan to return to the tea plants and the air turbulence produced by the frost protective fan would not reach the plants under the windy condition

Carbon isotope evidence for the latitudinal distribution and wind speed dependence of the air-sea gas transfer velocity

International Nuclear Information System (INIS)

Krakauer, Nir Y.

2006-01-01

The air-sea gas transfer velocity is an important determinant of the exchange of gases, including CO 2 , between the atmosphere and ocean, but the magnitude of the transfer velocity and what factors control it remains poorly known. Here, we use oceanic and atmospheric observations of 14 C and 13 C to constrain the global mean gas transfer velocity as well as the exponent of its wind speed dependence, utilizing the distinct signatures left by the air-sea exchange of 14 CO 2 and 13 CO 2 . While the atmosphere and ocean inventories of 14 CO 2 and 13 CO 2 constrain the mean gas transfer velocity, the latitudinal pattern in the atmospheric and oceanic 14 C and 13 C distributions contain information about the wind speed dependence. We computed the uptake of bomb 14 C by the ocean for different transfer velocity patterns using pulse response functions from an ocean general circulation model, and evaluated the match between the predicted bomb 14 C concentrations and observationally based estimates for the 1970s-1990s. Using a wind speed climatology based on satellite measurements, we solved either for the best-fit global relationship between gas exchange and mean wind speed or for the mean gas transfer velocity over each of 11 ocean regions. We also compared the predicted consequences of different gas exchange relationships on the rate of change and interhemisphere gradient of 14 C in atmospheric CO 2 with tree-ring and atmospheric measurements. Our results suggest that globally, the dependence of the air-sea gas transfer velocity on wind speed is close to linear, with an exponent of 0.5 ± 0.4, and that the global mean gas transfer velocity at a Schmidt number of 660 is 20 ± 3 cm/hr, similar to the results of previous analyses. We find that the air-sea flux of 13 C estimated from atmosphere and ocean observations also suggests a lower than quadratic dependence of gas exchange on wind speed

Local air gap thickness and contact area models for realistic simulation of human thermo-physiological response

Science.gov (United States)

Psikuta, Agnes; Mert, Emel; Annaheim, Simon; Rossi, René M.

2018-02-01

To evaluate the quality of new energy-saving and performance-supporting building and urban settings, the thermal sensation and comfort models are often used. The accuracy of these models is related to accurate prediction of the human thermo-physiological response that, in turn, is highly sensitive to the local effect of clothing. This study aimed at the development of an empirical regression model of the air gap thickness and the contact area in clothing to accurately simulate human thermal and perceptual response. The statistical model predicted reliably both parameters for 14 body regions based on the clothing ease allowances. The effect of the standard error in air gap prediction on the thermo-physiological response was lower than the differences between healthy humans. It was demonstrated that currently used assumptions and methods for determination of the air gap thickness can produce a substantial error for all global, mean, and local physiological parameters, and hence, lead to false estimation of the resultant physiological state of the human body, thermal sensation, and comfort. Thus, this model may help researchers to strive for improvement of human thermal comfort, health, productivity, safety, and overall sense of well-being with simultaneous reduction of energy consumption and costs in built environment.

SU-E-T-454: Impact of Air Gap On PDDs of 6 MV Photon Beam for Various Field Sizes in Inhomogeneous Phantoms

Energy Technology Data Exchange (ETDEWEB)

Oyewale, S [Cancer Centers of Southwest Oklahoma, Lawton, OK (United States); Pokharel [21st Century Oncology, Estero, FL (United States); Singh, H [Procure Proton Therapy Center, Oklahoma City, OK (United States); Islam, M [University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma (United States); Rana, S [ProCure Proton Therapy Center, Oklahoma City, OK (United States)

2015-06-15

Purpose: To investigate how the shape of air gap and its size will impact the percent depth doses (PDDs) of a 6MV photon beam for various field sizes. Methods: Two in-house phantoms were manufactured containing rectangular (phantom A) and circular (phantom B) air gaps. Both phantoms A and B were composed of same top layer (solid-water; 30×30cm{sup 2},5cm thickness) and bottom layer (solid-water; 30×30cm {sup 2},8cm thickness), but middle layer was varied to observe air gap effects and scatter contribution to the measurement point. In phantom A, a rectangular shaped air gap (30×30cm{sup 2},7cm thickness) was created by placing Styrofoam blocks between top and bottom layers of the phantom. In phantom B, middle layer was replaced by “inhomogenous block”, composed of acrylic plate (30×30cm{sup 2}, 4cm thickness) followed by PVC(30×30cm{sup 2},3cm thickness). Additionally, circular air gap was created by drilling a hole (diameter=2.8cm, length=7cm) at the center of “inhomogenous block”. In both phantoms, measurement readings were obtained at 13cm depth (i.e., 1cm after air gap) and depth of maximum dose(6MV energy; 100 MUs; field sizes ranged from 3×3cm{sup 2} to 10×10cm{sup 2}). The PDDs at 13cm depth were compared in both phantoms. Results: The measurements in both phantoms A and B showed an almost linear increase in PDDs with increasing field size, especially for smaller field sizes (from 3×3 to 7×7cm{sup 2}). For each field size, the PDD in phantom A was smaller compared to the one in phantom B. The difference in PDDs between two phantoms decreased with an increase in field size as the PDD difference decreased from 9.0% to 6.4%. Conclusion: The shape and size of air gap affect the PDD measurements in secondary build-up region as 6 MV primary beam traverses through the center of air gap. The scatter contribution due to increase in field size was more noticeable for field sizes ≤7×7cm{sup 2}.

Reduced thermal sensitivity of hybrid air-core photonic band-gap fiber ring resonator

Science.gov (United States)

Feng, Li-shuang; Wang, Kai; Jiao, Hong-chen; Wang, Jun-jie; Liu, Dan-ni; Yang, Zhao-hua

2018-01-01

A novel hybrid air-core photonic band-gap fiber (PBF) ring resonator with twin 90° polarization-axis rotated splices is proposed and demonstrated. Frist, we measure the temperature dependent birefringence coefficient of air-core PBF and Panda fiber. Experimental results show that the relative temperature dependent birefringence coefficient of air-core PBF is 1.42×10-8/°C, which is typically 16 times less than that of Panda fiber. Then, we extract the geometry profile of air-core PBF from scanning electron microscope (SEM) images. Numerical modal is built to distinguish the fast axis and slow axis in the fiber. By precisely setting the length difference in air-core PBF and Panda fiber between two 90° polarization-axis rotated splicing points, the hybrid air-core PBF ring resonator is constructed, and the finesse of the resonator is 8.4. Environmental birefringence variation induced by temperature change can be well compensated, and experimental results show an 18-fold reduction in thermal sensitivity, compared with resonator with twin 0° polarization-axis rotated splices.

Optimization of diesel engine performances for a hybrid wind-diesel system with compressed air energy storage

International Nuclear Information System (INIS)

Ibrahim, H.; Younes, R.; Basbous, T.; Ilinca, A.; Dimitrova, M.

2011-01-01

Electricity supply in remote areas around the world is mostly guaranteed by diesel generators. This relatively inefficient and expensive method is responsible for 1.2 million tons of greenhouse gas (GHG) emission in Canada annually. Some low- and high-penetration wind-diesel hybrid systems (WDS) have been experimented in order to reduce the diesel consumption. We explore the re-engineering of current diesel power plants with the introduction of high-penetration wind systems together with compressed air energy storage (CAES). This is a viable alternative to major the overall percentage of renewable energy and reduce the cost of electricity. In this paper, we present the operative principle of this hybrid system, its economic benefits and advantages and we finally propose a numerical model of each of its components. Moreover, we are demonstrating the energy efficiency of the system, particularly in terms of the increase of the engine performance and the reduction of its fuel consumption illustrated and supported by a village in northern Quebec. -- Highlights: → The Wind-Diesel-Compressed Air Storage System (WDCAS) has a very important commercial potential for remote areas. → The WDCAS is conceived like the adaptation of the existing engines at the level of the intake system. → A wind turbine and an air compression and storage system are added on the diesel plant. → This study demonstrates the potential of WDCAS to reduce fuel consumption and increase the efficiency of the diesel engine. → This study demonstrates that we can expect savings which can reach 50%.

Wind-Induced Air-Flow Patterns in an Urban Setting: Observations and Numerical Modeling

Science.gov (United States)

Sattar, Ahmed M. A.; Elhakeem, Mohamed; Gerges, Bishoy N.; Gharabaghi, Bahram; Gultepe, Ismail

2018-04-01

City planning can have a significant effect on wind flow velocity patterns and thus natural ventilation. Buildings with different heights are roughness elements that can affect the near- and far-field wind flow velocity. This paper aims at investigating the impact of an increase in building height on the nearby velocity fields. A prototype urban setting of buildings with two different heights (25 and 62.5 cm) is built up and placed in a wind tunnel. Wind flow velocity around the buildings is mapped at different heights. Wind tunnel measurements are used to validate a 3D-numerical Reynolds averaged Naviers-Stokes model. The validated model is further used to calculate the wind flow velocity patterns for cases with different building heights. It was found that increasing the height of some buildings in an urban setting can lead to the formation of large horseshoe vortices and eddies around building corners. A separation area is formed at the leeward side of the building, and the recirculation of air behind the building leads to the formation of slow rotation vortices. The opposite effect is observed in the wake (cavity) region of the buildings, where both the cavity length and width are significantly reduced, and this resulted in a pronounced increase in the wind flow velocity. A significant increase in the wind flow velocity in the wake region of tall buildings with a value of up to 30% is observed. The spatially averaged velocities around short buildings also increased by 25% compared to those around buildings with different heights. The increase in the height of some buildings is found to have a positive effect on the wind ventilation at the pedestrian level.

A study on suppressing transmittance fluctuations for air-gapped Glan-type polarizing prisms

Science.gov (United States)

Zhang, Chuanfa; Li, Dailin; Zhu, Huafeng; Li, Chuanzhi; Jiao, Zhiyong; Wang, Ning; Xu, Zhaopeng; Wang, Xiumin; Song, Lianke

2018-05-01

Light intensity transmittance is a key parameter for the design of polarizing prisms, while sometimes its experimental curves based on spatial incident angle presents periodical fluctuations. Here, we propose a novel method for completely suppressing these fluctuations via setting a glued error angle in the air gap of Glan-Taylor prisms. The proposal consists of: an accurate formula of the intensity transmittance for Glan-Taylor prisms, a numerical simulation and a contrast experiment of Glan-Taylor prisms for analyzing the causes of the fluctuations, and a simple method for accurately measuring the glued error angle. The result indicates that when the setting glued error angle is larger than the critical angle for a certain polarizing prism, the fluctuations can be completely suppressed, and a smooth intensity transmittance curve can be obtained. Besides, the critical angle in the air gap for suppressing the fluctuations is decreased with the increase of beam spot size. This method has the advantage of having less demand for the prism position in optical systems.

A numerical study on the mechanism and optimization of wind-break structures for indirect air-cooling towers

International Nuclear Information System (INIS)

Gu, Hongfang; Wang, Haijun; Gu, Yuqian; Yao, Jianan

2016-01-01

Highlights: • Numerical study on the optimization of windbreak structure for IDAC was conducted. • Windbreak wall is the most effective structure but is affected by wind direction. • The louver is next best and it can be flexibly adjusted at the windy conditions. • An optimal louver opening was obtained for achieving a good cooling performance. - Abstract: The heat transfer performance of indirect air-cooling (IDAC) towers in large power stations is sensitive to the ambient wind velocity. To ensure the economic and reliable operation of units under windy conditions, it is important to conduct research on the optimization of different wind-break structures. This paper uses computational fluid dynamics method (CFD) to simulate the heat transfer performance of a 1000 MW IDAC tower power stations with four different wind-break structures namely, cross walls, wind-break walls, cross line-screen, and louvers. The research results show that the order of the effective heat transfer improvement of four wind-break structures is the wind-break, cross wall, line-screen and louvers. The wind-break wall is the most optimal structure, but its performance is strictly influenced by the direction and velocity of the wind, and the cross walls and cross line-screen structure have similar limitation in the practice operation. The louver is installed in each sector, and it is the next best option for increasing the heat transfer performance. It can be flexibly adjusted based on the wind direction and velocity. With the decrease in the louver opening, k, there is a decrease in the heat transfer rate of the windward sectors, and a significant increase in the heat transfer rate of the leeward sectors. Thus the total heat transfer rate of the IDAC tower can be improved tremendously. Based on the analysis of heat transfer and air flow mechanisms, there is an optimal opening, k, which achieves the largest heat transfer performance in an IDAC tower at each wind velocity. This study

A note on the correlation between circular and linear variables with an application to wind direction and air temperature data in a Mediterranean climate

Science.gov (United States)

Lototzis, M.; Papadopoulos, G. K.; Droulia, F.; Tseliou, A.; Tsiros, I. X.

2018-04-01

There are several cases where a circular variable is associated with a linear one. A typical example is wind direction that is often associated with linear quantities such as air temperature and air humidity. The analysis of a statistical relationship of this kind can be tested by the use of parametric and non-parametric methods, each of which has its own advantages and drawbacks. This work deals with correlation analysis using both the parametric and the non-parametric procedure on a small set of meteorological data of air temperature and wind direction during a summer period in a Mediterranean climate. Correlations were examined between hourly, daily and maximum-prevailing values, under typical and non-typical meteorological conditions. Both tests indicated a strong correlation between mean hourly wind directions and mean hourly air temperature, whereas mean daily wind direction and mean daily air temperature do not seem to be correlated. In some cases, however, the two procedures were found to give quite dissimilar levels of significance on the rejection or not of the null hypothesis of no correlation. The simple statistical analysis presented in this study, appropriately extended in large sets of meteorological data, may be a useful tool for estimating effects of wind on local climate studies.

Thermoelastic/plastic analysis of waste-container sleeve: IV. Air gap influence on hole closure. Technical memorandum report (RSI-0019)

International Nuclear Information System (INIS)

Pariseau, W.G.

1975-01-01

A thermoelastic/plastic finite element analysis of the influence of an air-gap on hole closure about a waste-container/sleeve assembly emplaced in a typical repository room (SALT/4T Model) indicates that hole closure would be of the order of hundredths of an inch. Acceptable air-gap width is thus governed by the hole size required for emplacement efficiency. A refined mesh analysis and laboratory testing is suggested in order to further explore the possibility of eliminating the engineering necessity of the sleeve

Study of spatiotemporal dynamics of a nanosecond atmospheric-pressure dielectric barrier discharge in millimeter-long air gaps

Energy Technology Data Exchange (ETDEWEB)

Malashin, M. V.; Moshkunkov, S. I.; Khomich, V. Yu.; Shershunova, E. A., E-mail: eshershunova@gmail.com [Russian Academy of Sciences, Institute for Electrophysics and Electric Power (Russian Federation)

2017-02-15

The spatiotemporal dynamics of a nanosecond atmospheric-pressure dielectric barrier discharge in 1- to 3-mm-long air gaps was studied experimentally. By using a segmented electrode, data on the time evolution of the discharge in different regions of the discharge gap were obtained. The uniformity of the discharge over the cross section is estimated by analyzing the spatial distribution of its glow.

Satellite Observations of Imprint of Oceanic Current on Wind Stress by Air-Sea Coupling.

Science.gov (United States)

Renault, Lionel; McWilliams, James C; Masson, Sebastien

2017-12-18

Mesoscale eddies are present everywhere in the ocean and partly determine the mean state of the circulation and ecosystem. The current feedback on the surface wind stress modulates the air-sea transfer of momentum by providing a sink of mesoscale eddy energy as an atmospheric source. Using nine years of satellite measurements of surface stress and geostrophic currents over the global ocean, we confirm that the current-induced surface stress curl is linearly related to the current vorticity. The resulting coupling coefficient between current and surface stress (s τ [N s m -3 ]) is heterogeneous and can be roughly expressed as a linear function of the mean surface wind. s τ expresses the sink of eddy energy induced by the current feedback. This has important implications for air-sea interaction and implies that oceanic mean and mesoscale circulations and their effects on surface-layer ventilation and carbon uptake are better represented in oceanic models that include this feedback.

Forecasting Cool Season Daily Peak Winds at Kennedy Space Center and Cape Canaveral Air Force Station

Science.gov (United States)

Barrett, Joe, III; Short, David; Roeder, William

2008-01-01

The expected peak wind speed for the day is an important element in the daily 24-Hour and Weekly Planning Forecasts issued by the 45th Weather Squadron (45 WS) for planning operations at Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS). The morning outlook for peak speeds also begins the warning decision process for gusts ^ 35 kt, ^ 50 kt, and ^ 60 kt from the surface to 300 ft. The 45 WS forecasters have indicated that peak wind speeds are a challenging parameter to forecast during the cool season (October-April). The 45 WS requested that the Applied Meteorology Unit (AMU) develop a tool to help them forecast the speed and timing of the daily peak and average wind, from the surface to 300 ft on KSC/CCAFS during the cool season. The tool must only use data available by 1200 UTC to support the issue time of the Planning Forecasts. Based on observations from the KSC/CCAFS wind tower network, surface observations from the Shuttle Landing Facility (SLF), and CCAFS upper-air soundings from the cool season months of October 2002 to February 2007, the AMU created multiple linear regression equations to predict the timing and speed of the daily peak wind speed, as well as the background average wind speed. Several possible predictors were evaluated, including persistence, the temperature inversion depth, strength, and wind speed at the top of the inversion, wind gust factor (ratio of peak wind speed to average wind speed), synoptic weather pattern, occurrence of precipitation at the SLF, and strongest wind in the lowest 3000 ft, 4000 ft, or 5000 ft. Six synoptic patterns were identified: 1) surface high near or over FL, 2) surface high north or east of FL, 3) surface high south or west of FL, 4) surface front approaching FL, 5) surface front across central FL, and 6) surface front across south FL. The following six predictors were selected: 1) inversion depth, 2) inversion strength, 3) wind gust factor, 4) synoptic weather pattern, 5) occurrence of

Forests under climate change and air pollution: Gaps in understanding and future directions for research

International Nuclear Information System (INIS)

Matyssek, R.; Wieser, G.; Calfapietra, C.; Vries, W. de; Dizengremel, P.; Ernst, D.; Jolivet, Y.; Mikkelsen, T.N.; Mohren, G.M.J.; Le Thiec, D.; Tuovinen, J.-P.

2012-01-01

Forests in Europe face significant changes in climate, which in interaction with air quality changes, may significantly affect forest productivity, stand composition and carbon sequestration in both vegetation and soils. Identified knowledge gaps and research needs include: (i) interaction between changes in air quality (trace gas concentrations), climate and other site factors on forest ecosystem response, (ii) significance of biotic processes in system response, (iii) tools for mechanistic and diagnostic understanding and upscaling, and (iv) the need for unifying modelling and empirical research for synthesis. This position paper highlights the above focuses, including the global dimension of air pollution as part of climate change and the need for knowledge transfer to enable reliable risk assessment. A new type of research site in forest ecosystems (“supersites”) will be conducive to addressing these gaps by enabling integration of experimentation and modelling within the soil-plant-atmosphere interface, as well as further model development. - Highlights: ► Research needs are identified for forests under climate change and air pollution. ► Abiotic–biotic interactions in response impede tree-ecosystem upscaling. ► Integration of empirical and modelling research is advocated. ► The concept of multi-scale investigations at novel “Supersites” is propagated. ► “Supersites” warrant mechanistic understanding of soil-plant-atmosphere interface. - Forests under climate change and air pollution require empirical and modelling research needs to be integrated at novel “Supersites” through multi-scale investigations.

A micro-gap, air-filled ionisation chamber as a detector for criticality accident dosimetry

International Nuclear Information System (INIS)

Murawski, I.; Zielczynski, M.; Gryzinski, M.A.; Golnik, N.

2014-01-01

A micro-gap air-filled ionisation chamber was designed for criticality dosimetry. The special feature of the chamber is its very small gap between electrodes of only 0.3 mm. This prevents ion recombination at high dose rates and minimises the influence of gas on secondary particles spectrum. The electrodes are made of polypropylene because of higher content of hydrogen in this material, when compared with soft tissue. The difference between neutron and gamma sensitivity in such chamber becomes practically negligible. The chamber's envelope contains two specially connected capacitors, one for polarising the electrodes and the other for collecting the ionisation charge. Air-filled ionisation chamber with very small gap is a simple dosemeter, which fulfills the most desired properties of criticality accident dosemeters. Short ion collection time is achieved by combination of small gap and relatively high polarising voltage. For the same reason, parasitic recombination of ions in the chamber is negligibly small even at high dose rates. The difference between neutron and gamma sensitivity is small for tissue-equivalent chamber and is expected to become practically negligible when the chamber electrodes are made of polypropylene. Additional capacitor provides a broad measuring range from ∼0.1 Gy up to ∼25 Gy; however, leakage of electrical charge from polarising capacitor has to be observed and taken into account. Periodical re-charging of the device is necessary. Obviously, final test of the device in conditions simulating criticality accident is needed and will be performed as soon as available. (authors)

Active Power Controls from Wind Power: Bridging the Gaps

Energy Technology Data Exchange (ETDEWEB)

Ela, E. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Gevorgian, V. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Fleming, P. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Zhang, Y. C. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Singh, M. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Muljadi, E. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Scholbrook, A. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Aho, J. [Univ. of Colorado, Boulder, CO (United States); Buckspan, A. [Univ. of Colorado, Boulder, CO (United States); Pao, L. [Univ. of Colorado, Boulder, CO (United States); Singhvi, V. [Electric Power Research Inst. (EPRI), Palo Alto, CA (United States); Tuohy, A. [Electric Power Research Inst. (EPRI), Palo Alto, CA (United States); Pourbeik, P. [Electric Power Research Inst. (EPRI), Palo Alto, CA (United States); Brooks, D. [Electric Power Research Inst. (EPRI), Palo Alto, CA (United States); Bhatt, N. [Electric Power Research Inst. (EPRI), Palo Alto, CA (United States)

2014-01-01

This paper details a comprehensive study undertaken by the National Renewable Energy Laboratory, Electric Power Research Institute, and the University of Colorado to understand how the contribution of wind power providing active power control (APC) can benefit the total power system economics, increase revenue streams, improve the reliability and security of the power system, and provide superior and efficient response while reducing any structural and loading impacts that may reduce the life of the wind turbine or its components. The study includes power system simulations, control simulations, and actual field tests using turbines at NREL's National Wind Technology Center (NWTC). The study focuses on synthetic inertial control, primary frequency control, and automatic generation control, and analyzes timeframes ranging from milliseconds to minutes to the lifetime of wind turbines, locational scope ranging from components of turbines to large wind plants to entire synchronous interconnections, and additional topics ranging from economics to power system engineering to control design.

Experimental Study on Branch and Diffuse Type of Streamers in Leader Restrike of Long Air Gap Discharge

International Nuclear Information System (INIS)

Chen She; Zeng Rong; Zhuang Chijie; Zhou Xuan; Ding Yujian

2016-01-01

One of the main problems in the Ultra High Voltage (UHV) transmission project is to choose the external insulation distance, which requires a deep understanding of the long air gap discharge mechanism. The leader-streamer propagation is one of most important stages in long air gap discharge. In the conductor-tower lattice configuration, we have measured the voltage, the current on the high voltage side and the electric field in the gap. While the streamer in the leader-streamer system presented a conical or hyperboloid diffuse shape, the clear branch structure streamer in front of the leader was firstly observed by a high speed camera in the experiment. Besides, it is found that the leader velocity, width and injected charge for the branch type streamer are greater than those of a diffuse type. We propose that the phenomenon results from the high humidity, which was 15.5-16.5 g/m 3 in our experiment. (paper)

Using wind setdown and storm surge on Lake Erie to calibrate the air-sea drag coefficient.

Science.gov (United States)

Drews, Carl

2013-01-01

The air-sea drag coefficient controls the transfer of momentum from wind to water. In modeling storm surge, this coefficient is a crucial parameter for estimating the surge height. This study uses two strong wind events on Lake Erie to calibrate the drag coefficient using the Coupled Ocean Atmosphere Wave Sediment Transport (COAWST) modeling system and the the Regional Ocean Modeling System (ROMS). Simulated waves are generated on the lake with Simulating WAves Nearshore (SWAN). Wind setdown provides the opportunity to eliminate wave setup as a contributing factor, since waves are minimal at the upwind shore. The study finds that model results significantly underestimate wind setdown and storm surge when a typical open-ocean formulation without waves is used for the drag coefficient. The contribution of waves to wind setdown and storm surge is 34.7%. Scattered lake ice also increases the effective drag coefficient by a factor of 1.1.

Impact of Spatial Resolution on Wind Field Derived Estimates of Air Pressure Depression in the Hurricane Eye

Directory of Open Access Journals (Sweden)

Linwood Jones

2010-03-01

Full Text Available Measurements of the near surface horizontal wind field in a hurricane with spatial resolution of order 1–10 km are possible using airborne microwave radiometer imagers. An assessment is made of the information content of the measured winds as a function of the spatial resolution of the imager. An existing algorithm is used which estimates the maximum surface air pressure depression in the hurricane eye from the maximum wind speed. High resolution numerical model wind fields from Hurricane Frances 2004 are convolved with various HIRAD antenna spatial filters to observe the impact of the antenna design on the central pressure depression in the eye that can be deduced from it.

ASSESSING THE IMPACT OF WIND SPEED AND MIXING-LAYER HEIGHT ON AIR QUALITY IN KRAKOW (POLAND IN THE YEARS 2014-2015

Directory of Open Access Journals (Sweden)

Robert OLENIACZ

2016-05-01

Full Text Available The paper discusses the role of wind speed and mixing-layer height in shaping the levels of pollutant concentrations in the air of Krakow (Southern Poland. The hourly averaged measurements of concentrations of selected air pollutants and wind speed values from the period of 2014-2015, recorded at two of the air quality monitoring stations within Krakow (both industrial and urban background were used for this purpose. Temporal variability of mixing-layer height in the area of the monitoring stations was determined using numerical modelling with the CALMET model and the measurements derived from, i.a., two upper air stations. It was found that wind speed and mixing-layer height are in at least moderate agreement with the concentration values for some pollutants. For PM10, PM2.5, NO2, NOx, CO and C6H6 correlation coefficient is of negative value, which indicates that the low wind speed and low mixing-layer height may be the dominant reason for elevated concentrations of these substances in the air, especially in the winter months. Moderate but positive correlation was found between O3 concentrations and analysed meteorological parameters, proving that the availability of appropriate precursors and their inflow from the neighbouring areas have an important role in the formation of tropospheric ozone. On the other hand, in case of SO2, a weak both positive and negative correlation coefficient was obtained, depending on the period and location of the station concerned.

The Effect of Air Density on Sand Transport Structures and the Adobe Abrasion Profile: A Field Wind-Tunnel Experiment Over a Wide Range of Altitude

Science.gov (United States)

Han, Qingjie; Qu, Jianjun; Dong, Zhibao; Zu, Ruiping; Zhang, Kecun; Wang, Hongtao; Xie, Shengbo

2014-02-01

Aeolian sand transport results from interactions between the surface and the airflow above. Air density strongly constrains airflow characteristics and the resulting flow of sand, and therefore should not be neglected in sand transport models. In the present study, we quantify the influence of air density on the sand flow structure, sand transport rate, adobe abrasion profiles, and abrasion rate using a portable wind-tunnel in the field. For a given wind speed, the flow's ability to transport sand decreases at low air density, so total sand transport decreases, but the saltation height increases. Thus, the damage to human structures increases compared with what occurs at lower altitudes. The adobe abrasion rate by the cloud of blowing sand decreases exponentially with increasing height above the surface, while the wind erosion and dust emission intensity both increase with increasing air density. Long-term feedback processes between air density and wind erosion suggest that the development of low-altitude areas due to long-term deflation plays a key role in dust emission, and will have a profound significance for surface Aeolian processes and geomorphology.

Wind direction variations in the natural wind – A new length scale

DEFF Research Database (Denmark)

Johansson, Jens; Christensen, Silas Sverre

2018-01-01

During an observation period of e.g. 10min, the wind direction will differ from its mean direction for short periods of time, and a body of air will pass by from that direction before the direction changes once again. The present paper introduces a new length scale which we have labeled the angular...... length scale. This length scale expresses the average size of the body of air passing by from any deviation of wind direction away from the mean direction. Using metrological observations from two different sites under varying conditions we have shown that the size of the body of air relative to the mean...... size decreases linearly with the deviation from the mean wind direction when the deviation is normalized with the standard deviation of the wind direction. It is shown that this linear variation is independent of the standard deviation of the wind direction, and that the two full-scale data sets follow...

ANN Synthesis Model of Single-Feed Corner-Truncated Circularly Polarized Microstrip Antenna with an Air Gap for Wideband Applications

Directory of Open Access Journals (Sweden)

Zhongbao Wang

2014-01-01

Full Text Available A computer-aided design model based on the artificial neural network (ANN is proposed to directly obtain patch physical dimensions of the single-feed corner-truncated circularly polarized microstrip antenna (CPMA with an air gap for wideband applications. To take account of the effect of the air gap, an equivalent relative permittivity is introduced and adopted to calculate the resonant frequency and Q-factor of square microstrip antennas for obtaining the training data sets. ANN architectures using multilayered perceptrons (MLPs and radial basis function networks (RBFNs are compared. Also, six learning algorithms are used to train the MLPs for comparison. It is found that MLPs trained with the Levenberg-Marquardt (LM algorithm are better than RBFNs for the synthesis of the CPMA. An accurate model is achieved by using an MLP with three hidden layers. The model is validated by the electromagnetic simulation and measurements. It is enormously useful to antenna engineers for facilitating the design of the single-feed CPMA with an air gap.

Indoor air purification by dielectric barrier discharge combined with ionic wind: physical and microbiological investigations

Science.gov (United States)

Timmermann, E.; Prehn, F.; Schmidt, M.; Höft, H.; Brandenburg, R.; Kettlitz, M.

2018-04-01

A non-thermal plasma source based on a surface dielectric barrier discharge (DBD) is developed for purification of recirculating air in operating theatres in hospitals. This is a challenging application due to high flow rates, short treatment times and the low threshold for ozone in the ventilated air. Therefore, the surface DBD was enhanced in order to generate an ionic wind, which can deflect and thus, filter out airborne microorganisms. Electrical and gas diagnostics as well as microbiological experiments were performed in a downscaled plasma source under variation of various electrical parameters, but application-oriented airflow velocity and humidity. The dependence of electrical power and ozone concentration as well as charged particles in the plasma treated air on frequency, voltage and relative humidity is presented and discussed. The presence of humidity causes a more conductive dielectric surface and thus a weaker plasma formation, especially at low frequency. The airborne test bacteria, Escherichia coli, showed significant effect to plasma treatment (up to 20% reduction) and to plasma with ionic wind (up to 90% removal); especially a configuration with 70% removal and an accompanying ozone concentration of only 360 ppb is promising for future application.

Study and design of a hybrid wind-diesel-compressed air energy storage system for remote areas

International Nuclear Information System (INIS)

Ibrahim, H.; Younes, R.; Ilinca, A.; Dimitrova, M.; Perron, J.

2010-01-01

Remote areas around the world predominantly rely on diesel-powered generators for their electricity supply, a relatively expensive and inefficient technology that is responsible for the emission of 1.2 million tons of greenhouse gas (GHG) annually, only in Canada . Wind-diesel hybrid systems (WDS) with various penetration rates have been experimented to reduce diesel consumption of the generators. After having experimented wind-diesel hybrid systems (WDS) that used various penetration rates, we turned our focus to that the re-engineering of existing diesel power plants can be achieved most efficiently, in terms of cost and diesel consumption, through the introduction of high penetration wind systems combined with compressed air energy storage (CAES). This article compares the available technical alternatives to supercharge the diesel that was used in this high penetration wind-diesel system with compressed air storage (WDCAS), in order to identify the one that optimizes its cost and performances. The technical characteristics and performances of the best candidate technology are subsequently assessed at different working regimes in order to evaluate the varying effects on the system. Finally, a specific WDCAS system with diesel engine downsizing is explored. This proposed design, that requires the repowering of existing facilities, leads to heightened diesel power output, increased engine lifetime and efficiency and to the reduction of fuel consumption and GHG emissions, in addition to savings on maintenance and replacement cost.

Edge-state-dependent tunneling of dipole-exchange spin waves in submicrometer magnetic strips with an air gap.

Science.gov (United States)

Xing, X J; Zhang, D; Li, S W

2012-12-14

We have investigated the tunneling of dipole-exchange spin waves across an air gap in submicrometer-sized permalloy magnetic strips by means of micromagnetic simulations. The magnetizations beside the gap could form three distinct end-domain states with various strengths of dipolar coupling. Spin-wave tunneling through the gap at individual end-domain states is studied. It is found that the tunneling behavior is strongly dependent on these domain states. Nonmonotonic decay of transmission of spin waves with the increase of the gap width is observed. The underlying mechanism for these behaviors is proposed. The tunneling characteristics of the dipole-exchange spin waves differ essentially from those of the magnetostatic ones reported previously.

Controllable and affordable utility-scale electricity from intermittent wind resources and compressed air energy storage (CAES)

International Nuclear Information System (INIS)

Cavallo, Alfred

2007-01-01

World wind energy resources are substantial, and in many areas, such as the US and northern Europe, could in theory supply all of the electricity demand. However, the remote or challenging location (i.e. offshore) and especially the intermittent character of the wind resources present formidable barriers to utilization on the scale required by a modern industrial economy. All of these technical challenges can be overcome. Long distance transmission is well understood, while offshore wind technology is being developed rapidly. Intermittent wind power can be transformed to a controllable power source with hybrid wind/compressed air energy storage (CAES) systems. The cost of electricity from such hybrid systems (including transmission) is affordable, and comparable to what users in some modern industrial economies already pay for electricity. This approach to intermittent energy integration has many advantages compared to the current strategy of forcing utilities to cope with supply uncertainty and transmission costs. Above all, it places intermittent wind on an equal technical footing with every other generation technology, including nuclear power, its most important long-term competitor

Wind Turbine Test. Wind Matic WM 17S

DEFF Research Database (Denmark)

Friis Pedersen, Troels

The report describes standard measurements performed on a Wind-Matic WM 17S, 75 kW wind turbine. The measurements carried out and reported here comprises the power output, system efficiency, energy production, transmission efficiency, rotor power, rotor efficiency, air-brakes efficiency, structural...

Wind Turbine Test Wind Matic WM 15S

DEFF Research Database (Denmark)

Friis Pedersen, Troels

The report describes standard measurements performed on a Wind-Matic WM 15S, 55 kW wind turbine. The measurements carried out and reported here comprises the power output, system efficiency, energy production, transmission efficiency, rotor power, rotor efficiency, air-brakes efficiency, dynamical...

A Comparative Computational Fluid Dynamics Study on an Innovative Exhaust Air Energy Recovery Wind Turbine Generator

Directory of Open Access Journals (Sweden)

Seyedsaeed Tabatabaeikia

2016-05-01

Full Text Available Recovering energy from exhaust air systems of building cooling towers is an innovative idea. A specific wind turbine generator was designed in order to achieve this goal. This device consists of two Giromill vertical axis wind turbines (VAWT combined with four guide vanes and two diffuser plates. It was clear from previous literatures that no comprehensive flow behavior study had been carried out on this innovative device. Therefore, the working principle of this design was simulated using the Analysis System (ANSYS Fluent computational fluid dynamics (CFD package and the results were compared to experimental ones. It was perceived from the results that by introducing the diffusers and then the guide vanes, the overall power output of the wind turbine was improved by approximately 5% and 34%, respectively, compared to using VAWT alone. In the case of the diffusers, the optimum angle was found to be 7°, while for guide vanes A and B, it was 70° and 60° respectively. These results were in good agreement with experimental results obtained in the previous experimental study. Overall, it can be concluded that exhaust air recovery turbines are a promising form of green technology.

Design and analysis of a flux intensifying permanent magnet embedded salient pole wind generator

Science.gov (United States)

Guo, Yujing; Jin, Ping; Lin, Heyun; Yang, Hui; Lyu, Shukang

2018-05-01

This paper presents an improved flux intensifying permanent magnet embedded salient pole wind generator (FI-PMESPWG) with mirror symmetrical magnetizing directions permanent magnet (PM) for improving generator's performances. The air-gap flux densities, the output voltage, the cogging torque and the d- and q-axis inductances of FI-PMESPWG are all calculated and analyzed by using the finite element method (FEM). To highlight the advantages of the proposed FI-PMESPWG, an original permanent magnet embedded salient pole wind generator (PMESPWG) model is adopted for comparison under the same operating conditions. The calculating results show that the air-gap flux densities of FI-PMESPWG are intensified with the same magnet amounts because the PMs are set in a form of V shape in each pole. The difference between d-axis inductance and q-axis inductance of the proposed FI-PMESPWG is reduced. Thus, the output power of the proposed FI-PMESPWG reaches a higher value than that of the original PMESPWG at the same current phase angle. The cogging torque is diminished because the flux path is changed. All the analysis results indicate that the electromagnetic characteristics of the proposed FI-PMESPWG are significantly better than that of the original PMESPWG.

Effect of wind waves on air-sea gas exchange: proposal of an overall CO2 transfer velocity formula as a function of breaking-wave parameter

International Nuclear Information System (INIS)

Zhao, D.; Suzuki, Y.; Komori, S.

2003-01-01

A new formula for gas transfer velocity as a function of the breaking-wave parameter is proposed based on correlating gas transfer with whitecap coverage. The new formula for gas transfer across an air-sea interface depends not only on wind speed but also on wind-wave state. At the same wind speed, a higher gas transfer velocity will be obtained for a more developed wind-sea, which is represented by a smaller spectral peak frequency of wind waves. We suggest that the large uncertainties in the traditional relationship of gas transfer velocity with wind speed be ascribed to the neglect of the effect of wind waves. The breaking-wave parameter can be regarded as a Reynolds number that characterizes the intensity of turbulence associated with wind waves in the downward-bursting boundary layer (DBBL). DBBL provides an effective way to exchange gas across the air-sea interface, which might be related to the surface renewal

The Effect of Non-condensable Gases Removal on Air Gap Membrane Distillation: Experimental and Simulation Studies

KAUST Repository

Alsaadi, Ahmad S.

2014-01-01

-based technologies and holds the potential of being a cost-effective separation process that can utilize low-grade waste heat or renewable energy. MD has four different configurations; among them is Air Gap Membrane Distillation (AGMD) which is the second most

Measuring and modelling of the wind on the scale of tall wind turbines

DEFF Research Database (Denmark)

Floors, Rogier Ralph

The air flow in the lower atmosphere on the spatial scale of the modern wind turbines is studied. Because wind turbines are nowadays often taller than 100 m, the validity of current analytical and numerical atmospheric models has to be evaluated and more knowledge about the structure of the atmos......The air flow in the lower atmosphere on the spatial scale of the modern wind turbines is studied. Because wind turbines are nowadays often taller than 100 m, the validity of current analytical and numerical atmospheric models has to be evaluated and more knowledge about the structure...

The count of losses by eddy currents in the windings of electric motors with hollow anchor

Directory of Open Access Journals (Sweden)

N. V. Pribylova

2017-01-01

Full Text Available Given the rationale of taking into account losses on eddy currents in the windings of a low-inertia DC motors with offered magnetoelectric systems. Increased in recent years, the power of these motors (through the use of highly coercive magnets permanent caused an increase in the volume of copper in the air gap and the magnetic induction values. All this has values given rise to significant eddy currents in the windings made in the air gap, and hence the necessity of taking into account losses from these currents. The experimentally obtained dependence of the losses on eddy currents on the frequency of rotation for a DC motor with a hollow anchor with a power of 350 watts. The magnitude of these losses can reach 30% of the nominal power of the motor. Described mechanism of occurrence of losses. Eddy currents occur in areas with variable magnetic flux and cause the appearance of force, which is directed toward the velocity vector and inhibits the anchor. The directions of these currents, the vectors of magnetic induction, magnetic field and force acting on the conductor winding and a braking anchor. The proposed methods reduce losses: crushing contours of eddy currents and achieve uniform distribution of magnetic induction in the interpolar space of the motor. Shows their strengths and weaknesses. The crushing circuits of windings occur surge currents. To eliminate the losses on the surge currents it is necessary to apply a transposition of the conductors. Given a refined formula for finding the losses on eddy currents in the armature winding, the conductors of which is made in the form of a harness of several wires. Formula has shown a good convergence with experimental data.

环境风对直接空冷岛换热的影响%The Effects of Environment Wind on Heat Transfer of Direct Air Cooled Island

Institute of Scientific and Technical Information of China (English)

丁振宇; 陈巍; 田永兴; 李学智

2011-01-01

以国内蒙达电厂600MW直接空冷机组为例,针对当前直接空冷机组运行中的突出问题--环境风的不利影响,利用CFD数值模拟软件Fluent,对空冷岛外部流场进行数值模拟.发现炉后来风、热风回流、倒灌是造成空冷岛换热效率下降的主要因素,分析了炉后来风、热风回流、倒灌等对空冷岛外部流场和换热性能的影响机理,并得到环境风速与热风回流和倒灌的关系.%Taking Mengda 600MW direct air-cooled units ii our country into consideration,in view of serious hurdles of air-cooled units available-the unfavorable influences of Ambient Wind,we tentatively proceeds to making numerical simulation research on external flow field of direct air-cooled island by using CFD software Fluent. Found that the wind generating from the boiler house afterwards,hot air re-circulation and air inverse flow are the main factors of decline in the efficiency of air-cooled island heat. This paper proposed the mechanism of ambient wind impacts,and the analysis on such effects of the wind generating from the boiler house afterwards,hot air re-circulation and air inverse flow on external flow field and heat exchange efficiency of air-cooled island was thus been within reach, found out hot air re-circulation and air inverse flow relationship between the wind speed.

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).

Simulating and understanding the gap outflow and oceanic response over the Gulf of Tehuantepec during GOTEX

Science.gov (United States)

Hong, Xiaodong; Peng, Melinda; Wang, Shouping; Wang, Qing

2018-06-01

Tehuantepecer is a strong mountain gap wind traveling through Chivela Pass into eastern Pacific coast in southern Mexico, most commonly between October and February and brings huge impacts on local and surrounding meteorology and oceanography. Gulf of Tehuantepec EXperiment (GOTEX) was conducted in February 2004 to enhance the understanding of the strong offshore gap wind, ocean cooling, vertical circulations and interactions among them. The gap wind event during GOTEX was simulated using the U.S. Navy Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS®). The simulations are compared and validated with the observations retrieved from several satellites (GOES 10-12, MODIS/Aqua/Terra, TMI, and QuikSCAT) and Airborne EXpendable BathyThermograph (AXBT). The study shows that the gap wind outflow has a fanlike pattern expending from the coast and with a strong diurnal variability. The surface wind stress and cooling along the axis of the gap wind outflow caused intense upwelling and vertical mixing in the upper ocean; both contributed to the cooling of the ocean mixed layer under the gap wind. The cooling pattern of sea surface temperature (SST) also reflects temperature advection by the nearby ocean eddies to have a crescent shape. Two sensitivity experiments were conducted to understand the relative roles of the wind stress and heat flux on the ocean cooling. The control has more cooling right under the gap flow region than either the wind-stress-only or the heat-flux-only experiment. Overall, the wind stress has a slightly larger effect in bringing down the ocean temperature near the surface and plays a more important role in local ocean circulations beneath the mixed layer. The impact of surface heat flux on the ocean is more limited to the top 30 m within the mixed layer and is symmetric to the gap flow region by cooling the ocean under the gap flow region and reducing the warming on both sides. The effect of surface wind stress is to induce more cooling

Estimation of the ability to use a mass of air from a moving vehicle in wind turbine propulsion

Directory of Open Access Journals (Sweden)

Adam BAWORSKI

2015-09-01

Full Text Available This work presents division and classification of wind turbines according to the location of the axis of rotation and generated power. The work introduces applications of the wind turbines in electric energy generation with their direct development. The paper discusses indicators and exploitation parameters that characterize particular types of wind rotators. Dimension and construction factors, as well as work parameters, have been analyzed in order to choose the optimal rotator in the road infrastructure application. The aim of the analysis was to conduct further investigation to restore a mass of air from passing vehicles.

Wind power variations under humid and arid meteorological conditions

International Nuclear Information System (INIS)

Şen, Zekâi

2013-01-01

Highlights: • It indicates the role of weather parameters’ roles in the wind energy calculation. • Meteorological variables are more significant in arid regions for wind power. • It provides opportunity to take into consideration air density variability. • Wind power is presented in terms of the wind speed, temperature and pressure. - Abstract: The classical wind power per rotor area per time is given as the half product of the air density by third power of the wind velocity. This approach adopts the standard air density as constant (1.23 g/cm 3 ), which ignores the density dependence on air temperature and pressure. Weather conditions are not taken into consideration except the variations in wind velocity. In general, increase in pressure and decrease in temperature cause increase in the wind power generation. The rate of increase in the pressure has less effect on the wind power as compared with the temperature rate. This paper provides the wind power formulation based on three meteorological variables as the wind velocity, air temperature and air pressure. Furthermore, from the meteorology point of view any change in the wind power is expressed as a function of partial changes in these meteorological variables. Additionally, weather conditions in humid and arid regions differ from each other, and it is interesting to see possible differences between the two regions. The application of the methodology is presented for two meteorology stations in Istanbul, Turkey, as representative of the humid regions and Al-Madinah Al-Monawwarah, Kingdom of Saudi Arabia, for arid region, both on daily record bases for 2010. It is found that consideration of air temperature and pressure in the average wind power calculation gives about 1.3% decrease in Istanbul, whereas it is about 13.7% in Al-Madinah Al-Monawwarah. Hence, consideration of meteorological variables in wind power calculations becomes more significant in arid regions

Enhanced air dispersion modelling at a typical Chinese nuclear power plant site: Coupling RIMPUFF with two advanced diagnostic wind models.

Science.gov (United States)

Liu, Yun; Li, Hong; Sun, Sida; Fang, Sheng

2017-09-01

An enhanced air dispersion modelling scheme is proposed to cope with the building layout and complex terrain of a typical Chinese nuclear power plant (NPP) site. In this modelling, the California Meteorological Model (CALMET) and the Stationary Wind Fit and Turbulence (SWIFT) are coupled with the Risø Mesoscale PUFF model (RIMPUFF) for refined wind field calculation. The near-field diffusion coefficient correction scheme of the Atmospheric Relative Concentrations in the Building Wakes Computer Code (ARCON96) is adopted to characterize dispersion in building arrays. The proposed method is evaluated by a wind tunnel experiment that replicates the typical Chinese NPP site. For both wind speed/direction and air concentration, the enhanced modelling predictions agree well with the observations. The fraction of the predictions within a factor of 2 and 5 of observations exceeds 55% and 82% respectively in the building area and the complex terrain area. This demonstrates the feasibility of the new enhanced modelling for typical Chinese NPP sites. Copyright © 2017 Elsevier Ltd. All rights reserved.

Electrical characteristics and influence of the air-gap size in a trielectrode plasma curtain at atmospheric pressure

International Nuclear Information System (INIS)

Sosa, R; Artana, G; Grondona, D; Marquez, A; Kelly, H

2009-01-01

A study of the electrical characteristics of the trielectrode plasma curtain (TPC) discharge is presented. The influence of the air-gap size (for a fixed value of the inter-electrode distance) on the discharge behaviour has been exhaustively studied. The TPC discharge is based on the combination of a dielectric barrier discharge (DBD) with a corona discharge (CD) in a three electrode system, and basically it consists of the 'stretching' of a pure DBD by the action of a negative CD generated between the active electrode of the dielectric barrier and a remote third electrode. It was found that the general trend of the electrical characteristic curves (the average discharge current and the streamer frequency as functions of the AC and DC biasing voltages) was very similar for all the air-gap values considered. Our results indicate that the development of the TPC discharge requires two conditions: (a) the presence of a positive cycle of a well-developed DBD together with a CD where the remote electrode acts as the cathode and (b) a voltage drop between the DBD electrode and the remote electrode high enough to obtain an average electric field in the gap that must exceed a minimum average electric field value in the streamer channel necessary for its propagation across the gap (∼6.3 kV cm -1 in our experimental conditions).

Real-time approaches to the estimation of local wind velocity for a fixed-wing unmanned air vehicle

International Nuclear Information System (INIS)

Chan, W L; Lee, C S; Hsiao, F B

2011-01-01

Three real-time approaches to estimating local wind velocity for a fixed-wing unmanned air vehicle are presented in this study. All three methods work around the navigation equations with added wind components. The first approach calculates the local wind speed by substituting the ground speed and ascent rate data given by the Global Positioning System (GPS) into the navigation equations. The second and third approaches utilize the extended Kalman filter (EKF) and the unscented Kalman filter (UKF), respectively. The results show that, despite the nonlinearity of the navigation equations, the EKF performance is proven to be on a par with the UKF. A time-varying noise estimation method based on the Wiener filter is also discussed. Results are compared with the average wind speed measured on the ground. All three approaches are proven to be reliable with stated advantages and disadvantages

Modeling of air-gap membrane distillation process: A theoretical and experimental study

KAUST Repository

Alsaadi, Ahmad Salem

2013-06-03

A one dimensional (1-D) air gap membrane distillation (AGMD) model for flat sheet type modules has been developed. This model is based on mathematical equations that describe the heat and mass transfer mechanisms of a single-stage AGMD process. It can simulate AGMD modules in both co-current and counter-current flow regimes. The theoretical model was validated using AGMD experimental data obtained under different operating conditions and parameters. The predicted water vapor flux was compared to the flux measured at five different feed water temperatures, two different feed water salinities, three different air gap widths and two MD membranes with different average pore sizes. This comparison showed that the model flux predictions are strongly correlated with the experimental data, with model predictions being within +10% of the experimentally determined values. The model was then used to study and analyze the parameters that have significant effect on scaling-up the AGMD process such as the effect of increasing the membrane length, and feed and coolant flow rates. The model was also used to analyze the maximum thermal efficiency of the AGMD process by tracing changes in water production rate and the heat input to the process along the membrane length. This was used to understand the gain in both process production and thermal efficiency for different membrane surface areas and the resultant increases in process capital and water unit cost. © 2013 Elsevier B.V.

Real-time power angle determination of salient-pole synchronous machine based on air gap measurements

Energy Technology Data Exchange (ETDEWEB)

Despalatovic, Marin; Jadric, Martin; Terzic, Bozo [FESB University of Split, Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture, R. Boskovica bb, 21000 Split (Croatia)

2008-11-15

This paper presents a new method for the real-time power angle determination of the salient-pole synchronous machines. This method is based on the terminal voltage and air gap measurements, which are the common features of the hydroturbine generator monitoring system. The raw signal of the air gap sensor is used to detect the rotor displacement with reference to the fundamental component of the terminal voltage. First, the algorithm developed for the real-time power angle determination is tested using the synthetic data obtained by the standard machine model simulation. Thereafter, the experimental investigation is carried out on the 26 MVA utility generator. The validity of the method is verified by comparing with another method, which is based on a tooth gear mounted on the rotor shaft. The proposed real-time algorithm has an adequate accuracy and needs a very short processing time. For applications that do not require real-time processing, such as the estimation of the synchronous machine parameters, the accuracy is additionally increased by applying an off-line data-processing algorithm. (author)

Wind tunnel tests of modified cross, hemisflo, and disk-gap-band parachutes with emphasis in the transonic range

Science.gov (United States)

Foughner, J. T., Jr.; Alexander, W. C.

1974-01-01

Transonic wind-tunnel studies were conducted with modified cross, hemisflo, and disk-gap-band parachute models in the wake of a cone-cylinder shape forebody. The basic cross design was modified with the addition of a circumferential constraining band at the lower edge of the canopy panels. The tests covered a Mach number range of 0.3 to 1.2 and a dynamic pressure range from 479 Newtons per square meter to 5746 Newtons per square meter. The parachute models were flexible textile-type structures and were tethered to a rigid forebody with a single flexible riser. Different size models of the modified cross and disk-gap-band canopies were tested to evaluate scale effects. Model reference diameters were 0.30, 0.61, and 1.07 meters (1.0, 2.0, and 3.5 ft) for the modified cross; and nominal diameters of 0.25 and 0.52 meter (0.83 and 1.7 ft) for the disk-gap-band; and 0.55 meter (1.8 ft) for the hemisflo. Reefing information is presented for the 0.61-meter-diameter cross and the 0.52-meter-diameter disk-gap-band. Results are presented in the form of the variation of steady-state average drag coefficient with Mach number. General stability characteristics of each parachute are discussed. Included are comments on canopy coning, spinning, and fluttering motions.

Wind Resource Estimation using QuikSCAT Ocean Surface Winds

DEFF Research Database (Denmark)

Xu, Qing; Zhang, Guosheng; Cheng, Yongcun

2011-01-01

In this study, the offshore wind resources in the East China Sea and South China Sea were estimated from over ten years of QuikSCAT scatterometer wind products. Since the errors of these products are larger close to the coast due to the land contamination of radar backscatter signal...... and the complexity of air-sea interaction processes, an empirical relationship that adjusts QuikSCAT winds in coastal waters was first proposed based on vessel measurements. Then the shape and scale parameters of Weibull function are determined for wind resource estimation. The wind roses are also plotted. Results...

Performance Evaluation of a Modular Design of Wind Tower with Wetted Surfaces

Directory of Open Access Journals (Sweden)

Sajad M.R. Khani

2017-06-01

Full Text Available Wind towers or wind catchers, as passive cooling systems, can provide natural ventilation in buildings located in hot, arid regions. These natural cooling systems can provide thermal comfort for the building inhabitants throughout the warm months. In this paper, a modular design of a wind tower is introduced. The design, called a modular wind tower with wetted surfaces, was investigated experimentally and analytically. To determine the performance of the wind tower, air temperature, relative humidity (RH and air velocity were measured at different points. Measurements were carried out when the wind speed was zero. The experimental results were compared with the analytical ones. The results illustrated that the modular wind tower can decrease the air temperature significantly and increase the relative humidity of airflow into the building. The average differences for air temperature and air relative humidity between ambient air and air exiting from the wind tower were approximately 10 °C and 40%, respectively. The main advantage of the proposed wind tower is that it is a modular design that can reduce the cost of wind tower construction.

Analytical and numerical calculation of magnetic field distribution in the slotted air-gap of tangential surface permanent-magnet motors

Directory of Open Access Journals (Sweden)

Boughrara Kamel

2009-01-01

Full Text Available This paper deals with the analytical and numerical analysis of the flux density distribution in the slotted air gap of permanent magnet motors with surface mounted tangentially magnetized permanent magnets. Two methods for magnetostatic field calculations are developed. The first one is an analytical method in which the effect of stator slots is taken into account by modulating the magnetic field distribution by the complex relative air gap permeance. The second one is a numerical method using 2-D finite element analysis with consideration of Dirichlet and anti-periodicity (periodicity boundary conditions and Lagrange Multipliers for simulation of movement. The results obtained by the analytical method are compared to the results of finite-element analysis.

Performance and Economics of a Wind-Diesel Hybrid Energy System: Naval Air Landing Field, San Clemente Island, California; TOPICAL

International Nuclear Information System (INIS)

McKenna, Ed; Olsen, Timothy

1999-01-01

This report provides an overview of the wind resource, economics and operation of the recently installed wind turbines in conjunction with diesel power for the Naval Air Landing Field (NALF), San Clemente Island (SCI), California Project. The primary goal of the SCI wind power system is to operate with the existing diesel power plant and provide equivalent or better power quality and system reliability than the existing diesel system. The wind system is also intended to reduce, as far as possible, the use of diesel fuel and the inherent generation of nitrogen-oxide emissions and other pollutants. The first two NM 225/30 225kW wind turbines were installed and started shake-down operations on February 5, 1998. This report describes the initial operational data gathered from February 1998 through January 1999, as well as the SCI wind resource and initial cost of energy provided by the wind turbines on SCI. In support of this objective, several years of data on the wind resources of San Clemente Island were collected and compared to historical data. The wind resource data were used as input to economic and feasibility studies for a wind-diesel hybrid installation for SCI

Nocturnal drainage wind characteristics in two converging air sheds

International Nuclear Information System (INIS)

Gedayloo, T.; Clements, W.E.; Barr, S.; Archuleta, J.A.

1980-01-01

During the short experimental period in the Grants Basin of Northeastern New Mexico a survey was conducted on the complex meteorology of this area. Emphasis was placed on the nocturnal drainage flow because of the potential hazards to the populated areas of Milan and Grants from the effluents of the uranium mining and milling operation in this area. This investigation has shown that the nocturnal drainage flow patterns agree with the winds predicted on the basis of the complex terrain of the area. Because of the surface cooling at night (over 25 0 C during summer and about 20 0 C during winter), air from elevated surrounding areas flows to the low lying regions consequently setting up a nocturnal drainage flow. This regime exists over 60% of the time during summer months and over 65% of the time during winter months with a depth generally less than 200 m. In the San Mateo air shed the drainage flow is east northeast, and in the Ambrosia Lake air shed it is from northwest. The confluence of these two air flows contributes mainly to the drainage flow through the channel formed by La Ja Mesa and Mesa Montanosa. The analysis of data collected by the recording Flats Station confirms the prediction that although the area south of the channel region broadens considerably causing a reduction in flow speed, contributions from the southside of La Jara Mesa and Mesa Montanosa partly compensate for this reduction. The position of this recording station is 15 to 20 km from the populated towns of Milan and Grants. A drainage flow speed of approximately 2.2 m s -1 and the duration of over 11 hours as recorded by this station indicates that air from the San Mateo and Ambrosia Lake regions may be transported southwards to these population centers during a nocturnal period. In order to test this prediction, a series of multi-atmospheric tracer experiments were conducted in the Grants Basin

Wind Speed and Sea State Dependencies of Air-Sea Gas Transfer: Results From the High Wind Speed Gas Exchange Study (HiWinGS)

Science.gov (United States)

Blomquist, B. W.; Brumer, S. E.; Fairall, C. W.; Huebert, B. J.; Zappa, C. J.; Brooks, I. M.; Yang, M.; Bariteau, L.; Prytherch, J.; Hare, J. E.; Czerski, H.; Matei, A.; Pascal, R. W.

2017-10-01

A variety of physical mechanisms are jointly responsible for facilitating air-sea gas transfer through turbulent processes at the atmosphere-ocean interface. The nature and relative importance of these mechanisms evolves with increasing wind speed. Theoretical and modeling approaches are advancing, but the limited quantity of observational data at high wind speeds hinders the assessment of these efforts. The HiWinGS project successfully measured gas transfer coefficients (k660) with coincident wave statistics under conditions with hourly mean wind speeds up to 24 m s-1 and significant wave heights to 8 m. Measurements of k660 for carbon dioxide (CO2) and dimethylsulfide (DMS) show an increasing trend with respect to 10 m neutral wind speed (U10N), following a power law relationship of the form: k660 CO2˜U10N1.68 and k660 dms˜U10N1.33. Among seven high wind speed events, CO2 transfer responded to the intensity of wave breaking, which depended on both wind speed and sea state in a complex manner, with k660 CO2 increasing as the wind sea approaches full development. A similar response is not observed for DMS. These results confirm the importance of breaking waves and bubble injection mechanisms in facilitating CO2 transfer. A modified version of the Coupled Ocean-Atmosphere Response Experiment Gas transfer algorithm (COAREG ver. 3.5), incorporating a sea state-dependent calculation of bubble-mediated transfer, successfully reproduces the mean trend in observed k660 with wind speed for both gases. Significant suppression of gas transfer by large waves was not observed during HiWinGS, in contrast to results from two prior field programs.

Rain Sensor with Stacked Light Waveguide Having Tilted Air Gap

Directory of Open Access Journals (Sweden)

Kyoo Nam Choi

2014-01-01

Full Text Available Vehicle sensor to detect rain drop on and above waveguide utilizing light deflection and scattering was realized, keeping wide sensing coverage and sensitivity to detect mist accumulation. Proposed sensor structure under stacked light wave guide consisted of light blocking fixture surrounding photodetector and adjacent light source. Tilted air gap between stacked light waveguide and light blocking fixture played major role to increase sensitivity and to enhance linearity. This sensor structure eliminated complex collimating optics, while keeping wide sensing coverage using simple geometry. Detection algorithm based on time-to-intensity transformation process was used to convert raining intensity into countable raining process. Experimental result inside simulated rain chamber showed distinct different response between light rain and normal rain. Application as automobile rain sensor is expected.

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

Fragmented coastal boundary layer induced by gap winds

Science.gov (United States)

Caldeira, Rui M. A.; Iglesias, Isabel; Sala, Iria; Vieira, Rui R.; Bastos, Luísa

2015-04-01

The oceanic impact of offshore-localized winds in the NW Iberian Peninsula was studied. Satellite and in situ observations showed the formation of plumes protruding offshore from the coast. To study the dynamics of such episodes tee Coupled-Ocean-Atmosphere-Wave- Sediment Transport Modeling System (COAWST) was used to reproduce the coastal conditions of the nortwestern Iberian Peninsula, allowing the concurrent representation of local winds, waves, currents, and rivers runoff. The use of coupled models is of outmost importance in order to accurately study the impact of the local winds on the coastal currents. The NW Iberian Peninsula has prominent capes, promontories and submarine canyons, which produce persistent hydrodynamic features. Thus far, the scientific literature shows that the western Iberian rivers produce a recurrent combined plume often denominated as the Western Iberian Buoyant Plume (WIBP) which increases the stratification of the water column and produces a vertical retention mechanism that keeps the biological material inshore. The WIBP extends northward along the coast (over the inner-shelf), and forms a front with the warmer and more saline surface (offshore) waters. However during episodes of strong offshore winds this coastal boundary layer is broken interrupting the WIBP. Coastal orography allows the formation of down-valley winds that produce coastal jets, promoting the offshore transport of pollutants, larvae and sediments. Acknowledgments: Acknowledgments: Numerical model solutions were calculated at CIIMARs HPC unit, acquired and maintained by FCT pluriannual funds (PesTC/Mar/LA0015/2013), and RAIA (0313-RAIA-1-E) and RAIA.co (0520-RAIACO-1-E) projects. The NICC (POCTI/CTA/49563/2002) project provided databases for this work. Rui Caldeira was supported by funds from the ECORISK project (NORTE-07-0124-FEDER-000054), co-financed by the North Portugal Regional Operational Programme (ON.2 - O Novo Norte), under the National Strategic Reference

Forests under climate change and air pollution: Gaps in understanding and future directions for research

DEFF Research Database (Denmark)

Matyssek, R.; Wieser, G.; Calfapietra, C.

2012-01-01

Forests in Europe face significant changes in climate, which in interaction with air quality changes, may significantly affect forest productivity, stand composition and carbon sequestration in both vegetation and soils. Identified knowledge gaps and research needs include: (i) interaction between...... changes in air quality (trace gas concentrations), climate and other site factors on forest ecosystem response, (ii) significance of biotic processes in system response, (iii) tools for mechanistic and diagnostic understanding and upscaling, and (iv) the need for unifying modelling and empirical research...... for synthesis. This position paper highlights the above focuses, including the global dimension of air pollution as part of climate change and the need for knowledge transfer to enable reliable risk assessment. A new type of research site in forest ecosystems (“supersites”) will be conducive to addressing...

A modified model of axial flux permanent magnet generator for wind turbine applications

International Nuclear Information System (INIS)

Ashraf, M.M.

2014-01-01

The Axial Flux Permanent Magnet Generators (AFPMGs) are gaining immense attention in the modern era. The single stage AFPMG topology consists of one stator disc which is held stationery between two revolving rotor discs attached with a common shaft. The number of poles of AFPMG depends on the winding pattern in which the coils are connected in series within stator disc. Connecting the coils in begin-to-end winding pattern, doubles the number of poles which also increases the active mass of AFPMG. The AFPMG considering begin-to-end winding pattern, can be operated at half shaft speed. This AFPMG is also having greater air gap flux density which, ultimately, improves the power density parameter of AFPMG. In this paper, a modified AFPMG has been proposed which is designed by considering begin-to-end winding pattern. A 380W single phase, single stage prototype model has been developed and tested. The test results show that power density of designed AFPMG with begin-to-end winding pattern has been improved by 32% as compared to AFPMG with begin-to-begin winding pattern. The proposed low speed and high power density AFPMG model can be actively deployed for wind turbine applications. (author)

A generalized model for the air-sea transfer of dimethyl sulfide at high wind speeds

Science.gov (United States)

Vlahos, Penny; Monahan, Edward C.

2009-11-01

The air-sea exchange of dimethyl sulfide (DMS) is an important component of ocean biogeochemistry and global climate models. Both laboratory experiments and field measurements of DMS transfer rates have shown that the air-sea flux of DMS is analogous to that of other significant greenhouse gases such as CO2 at low wind speeds (10 m/s. The result is an attenuation of the dimensionless Henry's Law constant (H) where (Heff = H/(1 + (Cmix/Cw) ΦB) by a solubility enhancement Cmix/Cw, and the fraction of bubble surface area per m2 surface ocean.

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. PMID:25864467

A Comparison of numerical simulation models for predicting temperature in solidification analysis with reference to air gap formation

OpenAIRE

Kron , J.; Bellet , Michel; Ludwig , Andreas; Pustal , Bjorn; Wendt , Joachim; Fredriksson , Hasse

2004-01-01

International audience; As a result of its influence on heat transfer between cast part and mould, air gap formation is an important problem for many casting processes. The general explanation for gap formation is that, as a result of stresses and distortions that are created from inhomogeneous cooling, shrinkage of the casting and expansion of the mould occur. In this paper, different thermomechanical approaches are applied to a well defined casting process using three commercial and one inh...

Ground-level climate at a peatland wind farm in Scotland is affected by wind turbine operation

Science.gov (United States)

Armstrong, Alona; Burton, Ralph R.; Lee, Susan E.; Mobbs, Stephen; Ostle, Nicholas; Smith, Victoria; Waldron, Susan; Whitaker, Jeanette

2016-04-01

The global drive to produce low-carbon energy has resulted in an unprecedented deployment of onshore wind turbines, representing a significant land use change for wind energy generation with uncertain consequences for local climatic conditions and the regulation of ecosystem processes. Here, we present high-resolution data from a wind farm collected during operational and idle periods that shows the wind farm affected several measures of ground-level climate. Specifically, we discovered that operational wind turbines raised air temperature by 0.18 °C and absolute humidity (AH) by 0.03 g m-3 during the night, and increased the variability in air, surface and soil temperature throughout the diurnal cycle. Further, the microclimatic influence of turbines on air temperature and AH decreased logarithmically with distance from the nearest turbine. These effects on ground-level microclimate, including soil temperature, have uncertain implications for biogeochemical processes and ecosystem carbon cycling, including soil carbon stocks. Consequently, understanding needs to be improved to determine the overall carbon balance of wind energy.

Weather Research and Forecasting Model Wind Sensitivity Study at Edwards Air Force Base, CA

Science.gov (United States)

Watson, Leela R.; Bauman, William H., III; Hoeth, Brian

2009-01-01

This abstract describes work that will be done by the Applied Meteorology Unit (AMU) in assessing the success of different model configurations in predicting "wind cycling" cases at Edwards Air Force Base, CA (EAFB), in which the wind speeds and directions oscillate among towers near the EAFB runway. The Weather Research and Forecasting (WRF) model allows users to choose among two dynamical cores - the Advanced Research WRF (ARW) and the Non-hydrostatic Mesoscale Model (NMM). There are also data assimilation analysis packages available for the initialization of the WRF model - the Local Analysis and Prediction System (LAPS) and the Advanced Regional Prediction System (ARPS) Data Analysis System (ADAS). Having a series of initialization options and WRF cores, as well as many options within each core, creates challenges for local forecasters, such as determining which configuration options are best to address specific forecast concerns. The goal of this project is to assess the different configurations available and determine which configuration will best predict surface wind speed and direction at EAFB.

On the spatial hedging effectiveness of German wind power futures for wind power generators

DEFF Research Database (Denmark)

Christensen, Troels Sønderby; Pircalabu, Anca

2018-01-01

The wind power futures recently introduced on the German market fill the gap of a standardized product that addresses directly the volume risk in wind power trading. While the German wind power futures entail risk-reducing benefits for wind power generators generally speaking, it remains unclear...... the extent of these benefits across wind farms with different geographical locations. In this paper, we consider the wind utilization at 31 different locations in Germany, and for each site, we propose a copula model for the joint behavior of the site-specific wind index and the overall German wind index....... Our results indicate that static mixture copulas are preferred to the stand-alone copula models usually employed in the economic literature. Further, we find evidence of asymmetric dependence and upper tail dependence. To quantify the benefits of wind power futures at each wind site, we perform...

Early stages of wind wave and drift current generation under non-stationary wind conditions.

Science.gov (United States)

Robles-Diaz, Lucia; Ocampo-Torres, Francisco J.; Branger, Hubert

2016-04-01

Generation and amplification mechanisms of ocean waves are well understood under constant wind speed or limited fetch conditions. Under these situations, the momentum and energy transfers from air to water are also quite well known. However during the wind field evolution over the ocean, we may observe sometime high wind acceleration/deceleration situations (e.g. Mexican Tehuano or Mediterranean Mistral wind systems). The evolution of wave systems under these conditions is not well understood. The purpose of these laboratory experiments is to better understand the early stages of water-waves and surface-drift currents under non-stationary wind conditions and to determine the balance between transfers creating waves and surface currents during non-equilibrium situations. The experiments were conducted in the Institut Pythéas wind-wave facility in Marseille-France. The wave tank is 40 m long, 2.7 m wide and 1 m deep. The air section is 50 m long, 3 m wide and 1.8 m height. We used 11 different resistive wave-gauges located along the tank. The momentum fluxes in the air column were estimated from single and X hot-film anemometer measurements. The sampling frequency for wind velocity and surface displacement measurements was 256 Hz. Water-current measurements were performed with a profiling velocimeter. This device measures the first 3.5 cm of the water column with a frequency rate of 100Hz. During the experiments, the wind intensity was abruptly modified with a constant acceleration and deceleration over time. We observed that wind drag coefficient values for accelerated wind periods are lower than the ones reported in previous studies for constant wind speed (Large and Pond 1981; Ocampo-Torres et al. 2010; Smith 1980; Yelland and Taylor 1996). This is probably because the turbulent boundary layer is not completely developed during the increasing-wind sequence. As it was reported in some theoretical studies (Miles 1957; Phillips 1957; Kahma and Donelan 1988), we

Local air pollution in the Arctic: knowledge gaps, challenges and future directions

Science.gov (United States)

Law, K.; Schmale, J.; Anenberg, S.; Arnold, S.; Simpson, W. R.; Mao, J.; Starkweather, S.

2017-12-01

It is estimated that about 30 % of the world's undiscovered gas and 13 % of undiscovered oil resources are located in the Arctic. Sea ice loss with climate change is progressing rapidly and by 2050 the Arctic could be nearly sea ice free in summer. This will allow for Arctic industrialization, commercial shipping, fishing and tourism to increase. Given that the world population is projected to grow beyond 9 billion by mid-century needing more resources, partly to be found in the Arctic, it can be expected that the current urbanization trend in the region will accelerate in the future. Against this background, it is likely that new local emission sources emerge which may lead to increased burdens of air pollutants such as particulate matter (PM), reactive nitrogen, and ozone. Typical Arctic emission sources include road transport, domestic fuel burning, diesel emissions, as well as industrial sources such as oil and gas extraction, metallurgical smelting, power generation as well as shipping in coastal areas. These emissions and their impacts remain poorly quantified in the Arctic. Boreal wildfires can already affect summertime air quality and may increase in frequency and size in a warmer climate. Locally produced air pollution, in combination with cold, stagnant weather conditions and inversion layers in winter, can also lead to significant localized pollutant concentrations, often in exceedance of air quality standards. Despite these concerns, very few process studies on local air pollution in or near inhabited areas in the Arctic have been conducted, which significantly limits our understanding of atmospheric chemical reactions involving air pollutants under Arctic conditions (e.g., extremely cold and dry air with little solar radiation in winter) and their impacts on human health and ecosystems. We will provide an overview of our current understanding of local air pollution and its impacts in Arctic urban environments and highlight key gaps. We will discuss a

Claw-pole Synchronous Generator for Compressed Air Energy Storage

Directory of Open Access Journals (Sweden)

PAVEL Valentina

2013-05-01

Full Text Available This paper presents a claw-poles generator for compressed air energy storage systems. It is presented the structure of such a system used for compensating of the intermittency of a small wind energy system. For equipping of this system it is chosen the permanent magnet claw pole synchronous generator obtained by using ring NdFeB permanentmagnets instead of excitation coil. In such a way the complexity of the scheme is reduced and the generator become maintenance free. The new magnetic flux density in the air-gap is calculated by magneticreluctance method and by FEM method and the results are compared with measured values in the old and new generator.

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

Study and design of a hybrid wind-diesel-compressed air system for providing electricity to a remote telecommunication station; Etudes et conception d'un systeme hybride eolien-diesel-air comprime pour l'electrification d'une station de telecommunications isolee

Energy Technology Data Exchange (ETDEWEB)

Ibrahim, H.; Dimitrova, M. [TechnoCentre eolien Gaspesie-les Iles, Gaspe, PQ (Canada); Ilinca, A. [Quebec Univ., Rimouski, PQ (Canada); Perron, J. [Quebec Univ., Chicoutimi, PQ (Canada)

2010-07-01

This poster reported on a study that examined the feasibility of using a hybrid wind-diesel-compressed air system to produce electricity at remote telecommunication stations. Low and high penetration wind-diesel hybrid systems were studied in order to reduce the diesel consumption. The use of a high penetration wind-diesel system together with compressed air energy storage (CAES) was shown to be a viable alternative to improve the overall percentage of renewable energy and reduce the cost of electricity in remote areas where a good wind resource is available. Different technical solutions for the CAES system were compared. refs., figs.

Using C-Band Dual-Polarization Radar Signatures to Improve Convective Wind Forecasting at Cape Canaveral Air Force Station and NASA Kennedy Space Center

Science.gov (United States)

Amiot, Corey G.; Carey, Lawrence D.; Roeder, William P.; McNamara, Todd M.; Blakeslee, Richard J.

2017-01-01

The United States Air Force's 45th Weather Squadron (45WS) is the organization responsible for monitoring atmospheric conditions at Cape Canaveral Air Force Station and NASA Kennedy Space Center (CCAFS/KSC) and issuing warnings for hazardous weather conditions when the need arises. One such warning is issued for convective wind events, for which lead times of 30 and 60 minutes are desired for events with peak wind gusts of 35 knots or greater (i.e., Threshold-1) and 50 knots or greater (i.e., Threshold-2), respectively (Roeder et al. 2014).

Modelling of the negative discharge in long air gaps under impulse voltages

International Nuclear Information System (INIS)

Rakotonandrasana, J H; Beroual, A; Fofana, I

2008-01-01

This paper presents a self-consistent model enabling the description of the whole negative discharge sequence, initiated in long air gaps under impulse voltage waves. This sequence includes the different phases of the propagation such as the initiation of the first corona, the pilot leader, the electrode and space leaders, and their junction. The model consists of using a RLC equivalent electrical network, the parameters of which vary with time according to the discharge characteristics and geometry (R, L and C being, respectively, the resistance, the inductance and the capacitance). This model provides the spatial and temporal evolution of the entire discharge, the current and the corresponding electrical charge, the power and energy injected into the gap and the velocity. It also allows us to simulate an image converter working in streak or frame mode and the leader propagation velocities as well as the trajectory of the discharge obtained from a probabilistic distribution. The computed results are compared with experimental data. Good agreement between computed and experimental results was obtained for various test configurations

Empirical models of wind conditions on Upper Klamath Lake, Oregon

Science.gov (United States)

Buccola, Norman L.; Wood, Tamara M.

2010-01-01

Upper Klamath Lake is a large (230 square kilometers), shallow (mean depth 2.8 meters at full pool) lake in southern Oregon. Lake circulation patterns are driven largely by wind, and the resulting currents affect the water quality and ecology of the lake. To support hydrodynamic modeling of the lake and statistical investigations of the relation between wind and lake water-quality measurements, the U.S. Geological Survey has monitored wind conditions along the lakeshore and at floating raft sites in the middle of the lake since 2005. In order to make the existing wind archive more useful, this report summarizes the development of empirical wind models that serve two purposes: (1) to fill short (on the order of hours or days) wind data gaps at raft sites in the middle of the lake, and (2) to reconstruct, on a daily basis, over periods of months to years, historical wind conditions at U.S. Geological Survey sites prior to 2005. Empirical wind models based on Artificial Neural Network (ANN) and Multivariate-Adaptive Regressive Splines (MARS) algorithms were compared. ANNs were better suited to simulating the 10-minute wind data that are the dependent variables of the gap-filling models, but the simpler MARS algorithm may be adequate to accurately simulate the daily wind data that are the dependent variables of the historical wind models. To further test the accuracy of the gap-filling models, the resulting simulated winds were used to force the hydrodynamic model of the lake, and the resulting simulated currents were compared to measurements from an acoustic Doppler current profiler. The error statistics indicated that the simulation of currents was degraded as compared to when the model was forced with observed winds, but probably is adequate for short gaps in the data of a few days or less. Transport seems to be less affected by the use of the simulated winds in place of observed winds. The simulated tracer concentration was similar between model results when

Wind turbine generators having wind assisted cooling systems and cooling methods

Science.gov (United States)

Bagepalli, Bharat [Niskayuna, NY; Barnes, Gary R [Delanson, NY; Gadre, Aniruddha D [Rexford, NY; Jansen, Patrick L [Scotia, NY; Bouchard, Jr., Charles G.; Jarczynski, Emil D [Scotia, NY; Garg, Jivtesh [Cambridge, MA

2008-09-23

A wind generator includes: a nacelle; a hub carried by the nacelle and including at least a pair of wind turbine blades; and an electricity producing generator including a stator and a rotor carried by the nacelle. The rotor is connected to the hub and rotatable in response to wind acting on the blades to rotate the rotor relative to the stator to generate electricity. A cooling system is carried by the nacelle and includes at least one ambient air inlet port opening through a surface of the nacelle downstream of the hub and blades, and a duct for flowing air from the inlet port in a generally upstream direction toward the hub and in cooling relation to the stator.

Numerical analysis of air pollution in a combined field of land/sea breeze and mountain/valley wind

International Nuclear Information System (INIS)

Kitada, T.; Igarashi, K.; Owada, M.

1986-01-01

Air pollution in the presence of two types of local flows (i.e., land/sea breeze and mountain/valley wind) was studies by advection simulation of the cluster of hypothetical fluid particles, and transport/chemistry calculation employing a three-dimensional Eulerian model for 20 advected species and about 90 chemical reactions. Three-dimensional flow fields over the River Yahagi basin in Japan were estimated for 48 h using an objective method with routine wind observations. Those obtained showed characteristics of the combined local flows such that in the daytime sea breeze and valley wind tend to form one united flow with substantial wind velocity in the whole region and, in contrast, land breeze and mountain wind during the nighttime form two separated circulating flows with a clear weak-wind area between the two local flow regimes. The results of the advection simulation of fluid particles and the transport/chemistry calculation using those flows as inputs elucidated how the features found in the diurnally varying, complex local flows contribute to produce characteristic time-variations of the concentrations of both primary and secondary pollutants. Among others, dynamics of NO 2 , HNO 3 , PAN, O 3 , SO 2 , and SO 4 /sup =/ concentrations are discussed

Air Force Officer Accession Planning: Addressing Key Gaps in Meeting Career Field Academic Degree Requirements for Nonrated Officers

Science.gov (United States)

2016-06-09

C O R P O R A T I O N Research Report Air Force Officer Accession Planning Addressing Key Gaps in Meeting Career Field Academic Degree Requirements...potential performance, and how to include these quality measures in the classification process. The research sponsor asked us to focus on academic ...Andrew P., and James K. Lowe, “Decision Support for the Career Field Selection Process at the US Air Force Academy,” European Journal of Operational

Why is China’s wind power generation not living up to its potential?

Science.gov (United States)

Huenteler, Joern; Tang, Tian; Chan, Gabriel; Diaz Anadon, Laura

2018-04-01

Following a decade of unprecedented investment, China now has the world’s largest installed base of wind power capacity. Yet, despite siting most wind farms in the wind-rich Northern and Western provinces, electricity generation from Chinese wind farms has not reached the performance benchmarks of the United States and many other advanced economies. This has resulted in lower environmental, economic, and health benefits than anticipated. We develop a framework to explain the performance of the Chinese and US wind sectors, accounting for a comprehensive set of driving factors. We apply this framework to a novel dataset of virtually all wind farms installed in China and the United States through the end of 2013. We first estimate the wind sector’s technical potential using a methodology that produces consistent estimates for both countries. We compare this potential to actual performance and find that Chinese wind farms generated electricity at 37%–45% of their annual technical potential during 2006–2013 compared to 54%–61% in the United States. Our findings underscore that the larger gap between actual performance and technical potential in China compared to the United States is significantly driven by delays in grid connection (14% of the gap) and curtailment due to constraints in grid management (10% of the gap), two challenges of China’s wind power expansion covered extensively in the literature. However, our findings show that China’s underperformance is also driven by suboptimal turbine model selection (31% of the gap), wind farm siting (23% of the gap), and turbine hub heights (6% of the gap)—factors that have received less attention in the literature and, crucially, are locked-in for the lifetime of wind farms. This suggests that besides addressing grid connection delays and curtailment, China will also need policy measures to address turbine siting and technology choices to achieve its national goals and increase utilization up to US levels.

Wind erosion processes and control

Science.gov (United States)

Wind erosion continues to threaten the sustainability of our nations' soil, air, and water resources. To effectively apply conservation systems to prevent wind driven soil loss, an understanding of the fundamental processes of wind erosion is necessary so that land managers can better recognize the ...

Effects of slotting and unipolar flux on magnetic pull in a two-pole induction motor with an extra four-pole stator winding

Energy Technology Data Exchange (ETDEWEB)

Sinervo, A.

2013-06-01

This thesis is about the radial magnetic forces between the rotor and stator in twopole induction machines. The magnetic forces arise from rotor eccentricity. The asymmetric air-gap makes the flux density on one side of the rotor stronger than on the opposite side. This produces magnetic pull. The magnetic flux density distribution in the air-gap can be expressed with spatial harmonics, i.e. flux densities with different pole-pair numbers. In two-pole machines, the main part of the magnetic force is produced by the interaction of two- and fourpole flux unless the four-pole flux is damped by parallel paths in the stator winding or an extra four-pole stator winding. The rest of the force comes from the interaction of two-pole and unipolar flux and from the higher harmonics of the air-gap flux of which the slot harmonics are a major part. The force caused by the higher harmonics and the unipolar flux is studied in the case where a four-pole stator winding is used to reduce the four-pole flux. The higher harmonics are found to produce, in addition to the traditional unbalanced magnetic pull, a force similar to the effect of the unipolar flux and the two can be distinguished only by measuring the unipolar flux. In measurements at various operation points, the higher harmonics are found to produce much more force than the unipolar flux and two-pole flux but the unipolar flux is still significant. The four-pole winding also is used to actively control the four-pole flux and the magnetic forces. Designing the controller requires a low order model of the system. Such a model is derived and the effect of the slot harmonics and the unipolar flux are included in the model. Different measurements techniques and methods are presented to identify and validate the control model. The operation point dependence of the system dynamics is studied via measurements. All results are obtained from a 30 kW test motor. The rotor of the test machine has a long flexible shaft on external

Numerical modeling on air quality in an urban environment with changes of the aspect ratio and wind direction.

Science.gov (United States)

Yassin, Mohamed F

2013-06-01

Due to heavy traffic emissions within an urban environment, air quality during the last decade becomes worse year by year and hazard to public health. In the present work, numerical modeling of flow and dispersion of gaseous emissions from vehicle exhaust in a street canyon were investigated under changes of the aspect ratio and wind direction. The three-dimensional flow and dispersion of gaseous pollutants were modeled using a computational fluid dynamics (CFD) model which was numerically solved using Reynolds-averaged Navier-Stokes (RANS) equations. The diffusion flow field in the atmospheric boundary layer within the street canyon was studied for different aspect ratios (W/H=1/2, 3/4, and 1) and wind directions (θ=90°, 112.5°, 135°, and 157.5°). The numerical models were validated against wind tunnel results to optimize the turbulence model. The numerical results agreed well with the wind tunnel results. The simulation demonstrated that the minimum concentration at the human respiration height within the street canyon was on the windward side for aspect ratios W/H=1/2 and 1 and wind directions θ=112.5°, 135°, and 157.5°. The pollutant concentration level decreases as the wind direction and aspect ratio increase. The wind velocity and turbulence intensity increase as the aspect ratio and wind direction increase.

Wind and water tunnel testing of a morphing aquatic micro air vehicle.

Science.gov (United States)

Siddall, Robert; Ortega Ancel, Alejandro; Kovač, Mirko

2017-02-06

Aerial robots capable of locomotion in both air and water would enable novel mission profiles in complex environments, such as water sampling after floods or underwater structural inspections. The design of such a vehicle is challenging because it implies significant propulsive and structural design trade-offs for operation in both fluids. In this paper, we present a unique Aquatic Micro Air Vehicle (AquaMAV), which uses a reconfigurable wing to dive into the water from flight, inspired by the plunge diving strategy of water diving birds in the family Sulidae . The vehicle's performance is investigated in wind and water tunnel experiments, from which we develop a planar trajectory model. This model is used to predict the dive behaviour of the AquaMAV, and investigate the efficacy of passive dives initiated by wing folding as a means of water entry. The paper also includes first field tests of the AquaMAV prototype where the folding wings are used to initiate a plunge dive.

Wind Energy

Energy Technology Data Exchange (ETDEWEB)

Beurskens, H.J.M. [SET Analysis, Kievitlaan 26, 1742 AD Schagen (Netherlands); Brand, A.J. [Energy research Centre of the Netherlands ECN, Unit Wind Energy, P.O. Box 1, 1755 ZG Petten (Netherlands)

2013-02-15

Over the years, wind energy has become a major source of renewable energy worldwide. The present chapter addresses the wind resource, which is available for exploitation for large-scale electricity production, and its specific physical properties. Furthermore, the technical options available to convert the energy of the air flow into mechanical energy and electricity are described. Specific problems of large-scale integration of wind energy into the grid as well as the present and future market developments are described in this chapter. Finally, environmental aspects are discussed briefly.

SU-E-T-220: Computational Accuracy of Adaptive Convolution (AC) and Collapsed Cone Convolution (CCC) Algorithms in the Presence of Air Gaps

Energy Technology Data Exchange (ETDEWEB)

Oyewale, S [Cancer Centers of Southwest Oklahoma, Lawton, OK (United States); Pokharel, S [21st Century Oncology, Naples, FL (United States); Rana, S [ProCure Proton Therapy Center, Oklahoma City, OK (United States)

2015-06-15

Purpose: To compare the percentage depth dose (PDD) computational accuracy of Adaptive Convolution (AC) and Collapsed Cone Convolution (CCC) algorithms in the presence of air gaps. Methods: A 30×30×30 cm{sup 3} solid water phantom with two 5cm air gaps was scanned with a CT simulator unit and exported into the Phillips Pinnacle™ treatment planning system. PDDs were computed using the AC and CCC algorithms. Photon energy of 6 MV was used with field sizes of 3×3 cm{sup 2}, 5×5 cm{sup 2}, 10×10 cm{sup 2}, 15×15 cm{sup 2}, and 20×20 cm{sup 2}. Ionization chamber readings were taken at different depths in water for all the field sizes. The percentage differences in the PDDs were computed with normalization to the depth of maximum dose (dmax). The calculated PDDs were then compared with measured PDDs. Results: In the first buildup region, both algorithms overpredicted the dose for all field sizes and under-predicted for all other subsequent buildup regions. After dmax in the three water media, AC under-predicted the dose for field sizes 3×3 and 5×5 cm{sup 2} and overpredicted for larger field sizes, whereas CCC under-predicted for all field sizes. Upon traversing the first air gap, AC showed maximum differences of –3.9%, −1.4%, 2.0%, 2.5%, 2.9% and CCC had maximum differences of −3.9%, −3.0%,–3.1%, −2.7%, −1.8% for field sizes 3×3, 5×5, 10×10, 15×15, and 20×20 cm{sup 2} respectively. Conclusion: The effect of air gaps causes a significant difference in the PDDs computed by both the AC and CCC algorithms in secondary build-up regions. AC computed larger values for the PDDs except at smaller field sizes. For CCC, the size of the errors in prediction of the PDDs has an inverse relationship with respect to field size. These effects should be considered in treatment planning where significant air gaps are encountered.

Offshore wind farm harmonic resonance analysis, part I : Converter harmonic model

NARCIS (Netherlands)

Sun, Yin; De Jong, Erik; Cobben, J. F.G.; Cuk, Vladimir

2017-01-01

Offshore wind power technology has matured significantly and now directly competes with conventional and onshore wind power generation. Thanks to continuous technological developments and significant cost reduction, offshore wind power is closing the gap with the onshore wind power about the

Estonian wind climate

International Nuclear Information System (INIS)

Kull, Ain

1999-01-01

Estonia is situated on the eastern coast of the Baltic Sea. This is a region with intensive cyclonic activity and therefore with a relatively high mean wind speed. Atmospheric circulation and its seasonal variation determine the general character of the Estonian wind regime over the Atlantic Ocean and Eurasia. However, the Baltic sea itself is a very important factor affecting wind climate, it has an especially strong influence on the wind regime in costal areas. The mean energy density (W/m 2 ) is a wind energy characteristic that is proportional to the third power of wind speed and describes energy available in a flow of air through a unit area. The mean energy density is a characteristic which has practical importance in regional assessment of snowdrift, storm damage and wind energy

WindNet: Improving the impact assessment of wind power projects

Directory of Open Access Journals (Sweden)

Christopher R. Jones

2014-12-01

Full Text Available Growing international demand for renewable energy has led to rapid growth in the wind power sector and wind farms are becoming an increasingly common feature of landscapes and seascapes in many countries. However, as the most appropriate locations within established markets are taken up, and as wind power penetrates new markets, there is an increasing likelihood that proposed projects will encroach on sensitive landscapes and residential areas. This will present challenges for the industry, particularly due to the impact that public opinion can have upon the outcomes of planning decisions about specific projects. This article introduces the four key dimensions of the WindNet programme, which are helping to elucidate some of the socio-technical debates that will likely shape the future of the wind power sector. The article outlines studies investigating (1 public responses to cumulative landscape and visual impacts, (2 the auditory impact of wind power projects on human health, (3 the science of wind farm design and its implications for planning, and (4 the relevance of the democratic deficit explanation of the so-called "social gap" in wind farm siting. The outcomes of the research being conducted by WindNet stand to help reduce uncertainty within the planning process and assist in providing a more comprehensive and fairer assessment of the possible impacts associated with wind power project development.

Wind effects on RVACS performance

International Nuclear Information System (INIS)

Tzanos, C.

1995-01-01

The reactor vessel auxillary cooling system (RVACS) is a passive liquid-metal reactor decay-heat removal system. The RVACS performance is a function of the pressure difference between air flow inlet and outlet, of the air inlet temperature, of the air density variation along the flow path, and of the pressure loss characteristics of the path. The pressure difference can be affected by wind speed and direction. The objective of this project was to investigate the effects of wind on the performance of the RVACS, specifically, the heat release through the stacks, of a liquid-metal reactor

McCabe wind energy system

International Nuclear Information System (INIS)

Norton, R.; McCabe, F.; MacMichael, G.

1995-01-01

A wind machine utilizing novel low-speed air foils and shrouds has been developed and is now undergoing a refinement process. Energy generated by the machine at a variety of wind speeds is significant. Use of the machine to compress air, which can serve a variety of applications, simplifies the total power producing system ranking it economical and practical for use at a variety of locations to fill many energy requirements. (author)

McCabe wind energy system

Energy Technology Data Exchange (ETDEWEB)

Norton, R [Wyndmoor (United States); McCabe, F [Levr/Air, Inc., Doylestown (United States); MacMichael, G [Regional Technical College, Galway (Iran, Islamic Republic of)

1996-12-31

A wind machine utilizing novel low-speed air foils and shrouds has been developed and is now undergoing a refinement process. Energy generated by the machine at a variety of wind speeds is significant. Use of the machine to compress air, which can serve a variety of applications, simplifies the total power producing system ranking it economical and practical for use at a variety of locations to fill many energy requirements. (author)

McCabe wind energy system

Energy Technology Data Exchange (ETDEWEB)

Norton, R. [Wyndmoor (United States); McCabe, F. [Levr/Air, Inc., Doylestown (United States); MacMichael, G. [Regional Technical College, Galway (Iran, Islamic Republic of)

1995-12-31

A wind machine utilizing novel low-speed air foils and shrouds has been developed and is now undergoing a refinement process. Energy generated by the machine at a variety of wind speeds is significant. Use of the machine to compress air, which can serve a variety of applications, simplifies the total power producing system ranking it economical and practical for use at a variety of locations to fill many energy requirements. (author)

Wind energy power plants (wind farms) review and analysis

Energy Technology Data Exchange (ETDEWEB)

Newbold, K B; McKeary, M [McMaster Univ., Hamilton, ON (Canada). McMaster Inst. of Environment and Health

2010-07-01

Global wind power capacity has increased by an average cumulative rate of over 30 percent over the past 10 years. Although wind energy emits no air pollutants and facilities can often share spaces with other activities, public opposition to wind power development is an ongoing cause of concern. Development at the local level in Ontario has been met with fierce opposition on the basis of health concerns, aesthetic values, potential environmental impacts, and economic risks. This report was prepared for the Town of Wasaga Beach, and examined some of the controversy surrounding wind power developments through a review of evidence found in the scientific literature. The impacts of wind power developments related to noise, shadow flicker, avian mortality, bats, and real estate values were evaluated. The study included details of interviews conducted with individuals from Ontario localities where wind farms were located. 77 refs., 1 tab., 1 fig., 2 appendices.

Near Real Time MISR Wind Observations for Numerical Weather Prediction

Science.gov (United States)

Mueller, K. J.; Protack, S.; Rheingans, B. E.; Hansen, E. G.; Jovanovic, V. M.; Baker, N.; Liu, J.; Val, S.

2014-12-01

The Multi-angle Imaging SpectroRadiometer (MISR) project, in association with the NASA Langley Atmospheric Science Data Center (ASDC), has this year adapted its original production software to generate near-real time (NRT) cloud-motion winds as well as radiance imagery from all nine MISR cameras. These products are made publicly available at the ASDC with a latency of less than 3 hours. Launched aboard the sun-synchronous Terra platform in 1999, the MISR instrument continues to acquire near-global, 275 m resolution, multi-angle imagery. During a single 7 minute overpass of any given area, MISR retrieves the stereoscopic height and horizontal motion of clouds from the multi-angle data, yielding meso-scale near-instantaneous wind vectors. The ongoing 15-year record of MISR height-resolved winds at 17.6 km resolution has been validated against independent data sources. Low-level winds dominate the sampling, and agree to within ±3 ms-1 of collocated GOES and other observations. Low-level wind observations are of particular interest to weather forecasting, where there is a dearth of observations suitable for assimilation, in part due to reliability concerns associated with winds whose heights are assigned by the infrared brightness temperature technique. MISR cloud heights, on the other hand, are generated from stereophotogrammetric pattern matching of visible radiances. MISR winds also address data gaps in the latitude bands between geostationary satellite coverage and polar orbiting instruments that obtain winds from multiple overpasses (e.g. MODIS). Observational impact studies conducted by the Naval Research Laboratory (NRL) and by the German Weather Service (Deutscher Wetterdienst) have both demonstrated forecast improvements when assimilating MISR winds. An impact assessment using the GEOS-5 system is currently in progress. To benefit air quality forecasts, the MISR project is currently investigating the feasibility of generating near-real time aerosol products.

Science 101: What Causes Wind?

Science.gov (United States)

Robertson, William C.

2010-01-01

There's a quick and easy answer to this question. The Sun causes wind. Exactly how the Sun causes wind takes a bit to explain. We'll begin with what wind is. You've no doubt heard that wind is the motion of air molecules, which is true. Putting aside the huge leap of faith it takes for us to believe that we are experiencing the motion of millions…

On the Clouds of Bubbles Formed by Breaking Wind-Waves in Deep Water, and their Role in Air -- Sea Gas Transfer

Science.gov (United States)

Thorpe, S. A.

1982-02-01

Clouds of small bubbles generated by wind waves breaking and producing whitecaps in deep water have been observed below the surface by using an inverted echo sounder. The bubbles are diffused down to several metres below the surface by turbulence against their natural tendency to rise. Measurements have been made at two sites, one in fresh water at Loch Ness and the other in the sea near Oban, northwest Scotland. Sonagraph records show bubble clouds of two distinct types, `columnar clouds' which appear in unstable or convective conditions when the air temperature is less than the surface water temperature, and `billow clouds' which appear in stable conditions when the air temperature exceeds that of the water. Clouds penetrate deeper as the wind speed increases, and deeper in convective conditions than in stable conditions at the same wind speed. The response to a change in wind speed occurs in a period of only a few minutes. Measurements of the acoustic scattering cross section per unit volume, Mv, of the bubbles have been made at several depths. The distributions of Mv at constant depth are close to logarithmic normal. The time-averaged value of Mv, {M}v, decreases exponentially with depth over scales of 40-85 cm (winds up to 12 m s-1),, the scale increasing as the wind increases. Values of {M}v at the same depth and at the same wind speed are greater in the sea than in the fresh-water loch, even at smaller fetches. Estimates have been made of the least mean vertical speed at which bubbles must be advected for them to reach the observed depths. Several centimetres per second are needed, the speeds increasing with wind. Results depend on the conditions at the surfaces of the bubbles, that is whether they are covered by a surface active-film. The presence of oxygen (or gases other than nitrogen) in the gas composing the bubbles appears not to be important in determining their general behaviour. The presence of turbulence in the water also appears unlikely to affect

Baseload wind energy: modeling the competition between gas turbines and compressed air energy storage for supplemental generation

International Nuclear Information System (INIS)

Greenblatt, Jeffery B.; Succar, Samir; Denkenberger, David C.; Williams, Robert H.; Socolow, Robert H.

2007-01-01

The economic viability of producing baseload wind energy was explored using a cost-optimization model to simulate two competing systems: wind energy supplemented by simple- and combined cycle natural gas turbines ('wind+gas'), and wind energy supplemented by compressed air energy storage ('wind+CAES'). Pure combined cycle natural gas turbines ('gas') were used as a proxy for conventional baseload generation. Long-distance electric transmission was integral to the analysis. Given the future uncertainty in both natural gas price and greenhouse gas (GHG) emissions price, we introduced an effective fuel price, p NGeff , being the sum of the real natural gas price and the GHG price. Under the assumption of p NGeff =$5/GJ (lower heating value), 650 W/m 2 wind resource, 750 km transmission line, and a fixed 90% capacity factor, wind+CAES was the most expensive system at cents 6.0/kWh, and did not break even with the next most expensive wind+gas system until p NGeff =$9.0/GJ. However, under real market conditions, the system with the least dispatch cost (short-run marginal cost) is dispatched first, attaining the highest capacity factor and diminishing the capacity factors of competitors, raising their total cost. We estimate that the wind+CAES system, with a greenhouse gas (GHG) emission rate that is one-fourth of that for natural gas combined cycle plants and about one-tenth of that for pulverized coal plants, has the lowest dispatch cost of the alternatives considered (lower even than for coal power plants) above a GHG emissions price of $35/tC equiv. , with good prospects for realizing a higher capacity factor and a lower total cost of energy than all the competing technologies over a wide range of effective fuel costs. This ability to compete in economic dispatch greatly boosts the market penetration potential of wind energy and suggests a substantial growth opportunity for natural gas in providing baseload power via wind+CAES, even at high natural gas prices

Thermodynamic analysis of energy conversion and transfer in hybrid system consisting of wind turbine and advanced adiabatic compressed air energy storage

International Nuclear Information System (INIS)

Zhang, Yuan; Yang, Ke; Li, Xuemei; Xu, Jianzhong

2014-01-01

A simulation model consisting of wind speed, wind turbine and AA-CAES (advanced adiabatic compressed air energy storage) system is developed in this paper, and thermodynamic analysis on energy conversion and transfer in hybrid system is carried out. The impacts of stable wind speed and unstable wind speed on the hybrid system are analyzed and compared from the viewpoint of energy conversion and system efficiency. Besides, energy conversion relationship between wind turbine and AA-CAES system is investigated on the basis of process analysis. The results show that there are several different forms of energy in hybrid system, which have distinct conversion relationship. As to wind turbine, power coefficient determines wind energy utilization efficiency, and in AA-CAES system, it is compressor efficiency that mainly affects energy conversion efficiencies of other components. The strength and fluctuation of wind speed have a direct impact on energy conversion efficiencies of components of hybrid system, and within proper wind speed scope, the maximum of system efficiency could be expected. - Highlights: • A hybrid system consisting of wind, wind turbine and AA-CAES system is established. • Energy conversion in hybrid system with stable and unstable wind speed is analyzed. • Maximum efficiency of hybrid system can be reached within proper wind speed scope. • Thermal energy change in hybrid system is more sensitive to wind speed change. • Compressor efficiency can affect other efficiencies in AA-CAES system

Harmonic Fluxes and Electromagnetic Forces of Concentric Winding Brushless Permanent Magnet Motor

Science.gov (United States)

Ishibashi, Fuminori; Takemasa, Ryo; Matsushita, Makoto; Nishizawa, Takashi; Noda, Shinichi

Brushless permanent magnet motors have been widely used in home applications and industrial fields. These days, high efficiency and low noise motors are demanded from the view point of environment. Electromagnetic noise and iron loss of the motor are produced by the harmonic fluxes and electromagnetic forces. However, order and space pattern of these have not been discussed in detail. In this paper, fluxes, electromagnetic forces and magneto-motive forces of brushless permanent magnet motors with concentric winding were analyzed analytically, experimentally and numerically. Time harmonic fluxes and time electromagnetic forces in the air gap were measured by search coils on the inner surface of the stator teeth and analyzed by FEM. Space pattern of time harmonic fluxes and time electromagnetic forces were worked out with experiments and FEM. Magneto motive forces due to concentric winding were analyzed with equations and checked by FEM.

Wind shear coefficients and their effect on energy production

International Nuclear Information System (INIS)

Rehman, Shafiqur; Al-Abbadi, Naif M.

2005-01-01

This paper provides realistic values of wind shear coefficients calculated using measured values of wind speed at 20, 30 and 40 m above the ground for the first time in Saudi Arabia in particular and, to the best of the authors' knowledge, in the Gulf region in general. The paper also presents air density values calculated using the measured air temperature and surface pressure and the effects of wind shear factor on energy production from wind machines of different sizes. The measured data used in the study covered a period of almost three years between June 17, 1995 and December 1998. An overall mean value of wind shear coefficient of 0.194 can be used with confidence to calculate the wind speed at different heights if measured values are known at one height. The study showed that the wind shear coefficient is significantly influenced by seasonal and diurnal changes. Hence, for precise estimations of wind speed at a height, both monthly or seasonal and hourly or night time and day time average values of wind shear coefficient must be used. It is suggested that the wind shear coefficients must be calculated either (i) using long term average values of wind speed at different heights or (ii) using those half hourly mean values of wind speed for which the wind shear coefficient lies in the range 0 and 0.51. The air density, calculated using measured temperature and pressure was found to be 1.18 kg/m 3 . The air density values were also found to vary with the season of the year and hour of the day, and hence, care must be taken when precise calculations are to be made. The air density values, as shown in this paper, have no significant variation with height. The energy production analysis showed that the actual wind shear coefficient presented in this paper produced 6% more energy compared to that obtained using the 1/7 power law. Similarly, higher plant capacity factors were obtained with the wind shear factor of 0.194 compared to that with 0.143

Wind Turbine Generator System Power Performance Test Report for the ARE442 Wind Turbine

Energy Technology Data Exchange (ETDEWEB)

van Dam, J.; Jager, D.

2010-02-01

This report summarizes the results of a power performance test that NREL conducted on the ARE 442 wind turbine. This test was conducted in accordance with the International Electrotechnical Commission's (IEC) standard, Wind Turbine Generator Systems Part 12: Power Performance Measurements of Electricity Producing Wind Turbines, IEC 61400-12-1 Ed.1.0, 2005-12. However, because the ARE 442 is a small turbine as defined by IEC, NREL also followed Annex H that applies to small wind turbines. In these summary results, wind speed is normalized to sea-level air density.

Atmospheric diffusion wind tunnel with automatic measurement

Energy Technology Data Exchange (ETDEWEB)

Maki, S; Sakai, J; Murata, E

1974-01-01

A wind tunnel which permits estimates of atmospheric diffusion is described. Smoke from power plant smoke stacks, for example, can be simulated and traced to determine the manner of diffusion in the air as well as the grade of dilution. The wind tunnel is also capable of temperature controlled diffusion tests in which temperature distribution inside the wind tunnel is controlled. A minimum wind velocity of 10 cm can be obtained with accuracy within plus or minus 0.05 percent using a controlled direct current motor; diffusion tests are often made at low wind velocity. Fully automatic measurements can be obtained by using a minicomputer so that the operation and reading of the measuring instruments can be remotely controlled from the measuring chamber. (Air Pollut. Abstr.)

Wind speed forecasting in the central California wind resource area

Energy Technology Data Exchange (ETDEWEB)

McCarthy, E.F. [Wind Economics & Technology, Inc., Martinez, CA (United States)

1997-12-31

A wind speed forecasting program was implemented in the summer seasons of 1985 - 87 in the Central California Wind Resource Area (WRA). The forecasting program is designed to use either meteorological observations from the WRA and local upper air observations or upper air observations alone to predict the daily average windspeed at two locations. Forecasts are made each morning at 6 AM and are valid for a 24 hour period. Ease of use is a hallmark of the program as the daily forecast can be made using data entered into a programmable HP calculator. The forecasting program was the first step in a process to examine whether the electrical energy output of an entire wind power generation facility or defined subsections of the same facility could be predicted up to 24 hours in advance. Analysis of the results of the summer season program using standard forecast verification techniques show the program has skill over persistence and climatology.

Retrieval of vertical wind profiles during monsoon from satellite ...

Indian Academy of Sciences (India)

Complex EOF analysis; cloud motion vector winds; wind profiles; retrieval; monsoon. Proc. Indian Acad. Sci. .... The data gaps are removed using simple linear interpolation .... retrieved via standard linear regression using the two independent ...

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.

Wind power plants the fuel savers

International Nuclear Information System (INIS)

Akbar, M.

2006-01-01

Wind is a converted from of solar energy. The Sun's radiation heats different parts of the earth at variable rates as the earth surfaces absorb or reflect at different rates. This in turn causes portions of the atmosphere to warm at varying levels. The hot air rises reducing atmospheric pressure at the earth's surface beneath, the cooler air rushes to replace it and in the process creates a momentum called wind. Air possesses mass and when it sets into motion, it contains the energy of that motion, called the Kinetic Energy. A part of the Kinetic Energy of the wind can be converted into other forms of energy i.e. mechanical force or electric power that can be used to perform work. The cost of electric energy from the wind system has dropped from the initial cost of 30 to 40 Cents per kWh to about 5 to 7 Cents/k Wh during the past 20 years. The costs are continually declining as the technology is advanced, the unit size is increased and larger plants are built. Wind power is now a viable, robust and fast growing industry. The cost of wind energy is expected to drop to 2 to 3 Cents / kWh during the next 5 to 10 years. Due to sky-rocketing prices of the fossil fuels, the competitive position of power generation technologies is rapidly changing. Wind energy is likely to emerge as the cheapest source of electric power generation in the global market in the near future. The current assessment of the global wind resources indicate that the wind energy potential is more than double the world's electricity needs. (author)

Gap in air pollution reduction measures

International Nuclear Information System (INIS)

Kamphuis, E.; Spijker, E.

2006-01-01

The air quality dossier in the Netherlands requires drastic cleaning of the vehicles fleet. However, the present measures are too much focused on the installation and use of soot filters. Other options to improve the air quality are discussed [nl

Incorporating geostrophic wind information for improved space–time short-term wind speed forecasting

KAUST Repository

Zhu, Xinxin

2014-09-01

Accurate short-term wind speed forecasting is needed for the rapid development and efficient operation of wind energy resources. This is, however, a very challenging problem. Although on the large scale, the wind speed is related to atmospheric pressure, temperature, and other meteorological variables, no improvement in forecasting accuracy was found by incorporating air pressure and temperature directly into an advanced space-time statistical forecasting model, the trigonometric direction diurnal (TDD) model. This paper proposes to incorporate the geostrophic wind as a new predictor in the TDD model. The geostrophic wind captures the physical relationship between wind and pressure through the observed approximate balance between the pressure gradient force and the Coriolis acceleration due to the Earth’s rotation. Based on our numerical experiments with data from West Texas, our new method produces more accurate forecasts than does the TDD model using air pressure and temperature for 1to 6-hour-ahead forecasts based on three different evaluation criteria. Furthermore, forecasting errors can be further reduced by using moving average hourly wind speeds to fit the diurnal pattern. For example, our new method obtains between 13.9% and 22.4% overall mean absolute error reduction relative to persistence in 2-hour-ahead forecasts, and between 5.3% and 8.2% reduction relative to the best previous space-time methods in this setting.

Wind variability and sheltering effects on measurements and modeling of air-water exchange for a small lake

Science.gov (United States)

Markfort, Corey D.; Resseger, Emily; Porté-Agel, Fernando; Stefan, Heinz

2014-05-01

Lakes with a surface area of less than 10 km2 account for over 50% of the global cumulative lake surface water area, and make up more than 99% of the total number of global lakes, ponds, and wetlands. Within the boreal regions as well as some temperate and tropical areas, a significant proportion of land cover is characterized by lakes or wetlands, which can have a dramatic effect on land-atmosphere fluxes as well as the local and regional energy budget. Many of these small water bodies are surrounded by complex terrain and forest, which cause the wind blowing over a small lake or wetland to be highly variable. Wind mixing of the lake surface layer affects thermal stratification, surface temperature and air-water gas transfer, e.g. O2, CO2, and CH4. As the wind blows from the land to the lake, wake turbulence behind trees and other shoreline obstacles leads to a recirculation zone and enhanced turbulence. This wake flow results in the delay of the development of wind shear stress on the lake surface, and the fetch required for surface shear stress to fully develop may be ~O(1 km). Interpretation of wind measurements made on the lake is hampered by the unknown effect of wake turbulence. We present field measurements designed to quantify wind variability over a sheltered lake. The wind data and water column temperature profiles are used to evaluate a new method to quantify wind sheltering of lakes that takes into account lake size, shape and the surrounding landscape features. The model is validated against field data for 36 Minnesota lakes. Effects of non-uniform sheltering and lake shape are also demonstrated. The effects of wind sheltering must be included in lake models to determine the effect of wind-derived energy inputs on lake stratification, surface gas transfer, lake water quality, and fish habitat. These effects are also important for correctly modeling momentum, heat, moisture and trace gas flux to the atmosphere.

Gap-filling meteorological variables with Empirical Orthogonal Functions

Science.gov (United States)

Graf, Alexander

2017-04-01

Gap-filling or modelling surface-atmosphere fluxes critically depends on an, ideally continuous, availability of their meteorological driver variables, such as e.g. air temperature, humidity, radiation, wind speed and precipitation. Unlike for eddy-covariance-based fluxes, data gaps are not unavoidable for these measurements. Nevertheless, missing or erroneous data can occur in practice due to instrument or power failures, disturbance, and temporary sensor or station dismounting for e.g. agricultural management or maintenance. If stations with similar measurements are available nearby, using their data for imputation (i.e. estimating missing data) either directly, after an elevation correction or via linear regression, is usually preferred over linear interpolation or monthly mean diurnal cycles. The popular implementation of regional networks of (partly low-cost) stations increases both, the need and the potential, for such neighbour-based imputation methods. For repeated satellite imagery, Beckers and Rixen (2003) suggested an imputation method based on empirical orthogonal functions (EOFs). While exploiting the same linear relations between time series at different observation points as regression, it is able to use information from all observation points to simultaneously estimate missing data at all observation points, provided that never all observations are missing at the same time. Briefly, the method uses the ability of the first few EOFs of a data matrix to reconstruct a noise-reduced version of this matrix; iterating missing data points from an initial guess (the column-wise averages) to an optimal version determined by cross-validation. The poster presents and discusses lessons learned from adapting and applying this methodology to station data. Several years of 10-minute averages of air temperature, pressure and humidity, incoming shortwave, longwave and photosynthetically active radiation, wind speed and precipitation, measured by a regional (70 km by

Wind energy statistics

International Nuclear Information System (INIS)

Holttinen, H.; Tammelin, B.; Hyvoenen, R.

1997-01-01

The recording, analyzing and publishing of statistics of wind energy production has been reorganized in cooperation of VTT Energy, Finnish Meteorological (FMI Energy) and Finnish Wind Energy Association (STY) and supported by the Ministry of Trade and Industry (KTM). VTT Energy has developed a database that contains both monthly data and information on the wind turbines, sites and operators involved. The monthly production figures together with component failure statistics are collected from the operators by VTT Energy, who produces the final wind energy statistics to be published in Tuulensilmae and reported to energy statistics in Finland and abroad (Statistics Finland, Eurostat, IEA). To be able to verify the annual and monthly wind energy potential with average wind energy climate a production index in adopted. The index gives the expected wind energy production at various areas in Finland calculated using real wind speed observations, air density and a power curve for a typical 500 kW-wind turbine. FMI Energy has produced the average figures for four weather stations using the data from 1985-1996, and produces the monthly figures. (orig.)

UAS Air Traffic Controller Acceptability Study-2: Effects of Communications Delays and Winds in Simulation

Science.gov (United States)

Comstock, James R., Jr.; Ghatas, Rania W.; Consiglio, Maria C.; Chamberlain, James P.; Hoffler, Keith D.

2016-01-01

This study evaluated the effects of Communications Delays and Winds on Air Traffic Controller ratings of acceptability of horizontal miss distances (HMDs) for encounters between UAS and manned aircraft in a simulation of the Dallas-Ft. Worth East-side airspace. Fourteen encounters per hour were staged in the presence of moderate background traffic. Seven recently retired controllers with experience at DFW served as subjects. Guidance provided to the UAS pilots for maintaining a given HMD was provided by information from self-separation algorithms displayed on the Multi-Aircraft Simulation System. Winds tested did not affect the acceptability ratings. Communications delays tested included 0, 400, 1200, and 1800 msec. For longer communications delays, there were changes in strategy and communications flow that were observed and reported by the controllers. The aim of this work is to provide useful information for guiding future rules and regulations applicable to flying UAS in the NAS.

Wind gust measurements using pulsed Doppler wind-lidar: comparison of direct and indirect techniques

DEFF Research Database (Denmark)

The measurements of wind gusts, defined as short duration wind speed maxima, have traditionally been limited by the height that can be reached by weather masts. Doppler lidars can potentially provide information from levels above this and thereby fill this gap in our knowledge. To measure the 3D...... is 3.9 s) which can provide high resolution turbulent measurements, both in the vertical direction, and potentially in the horizontal direction. In this study we explore different strategies of wind lidar measurements to measure the wind speed maxima. We use a novel stochastic turbulence reconstruction...... model, driven by the Doppler lidar measurements, which uses a non-linear particle filter to estimate the small-scale turbulent fluctuations. The first results show that the reconstruction method can reproduce the wind speed maxima measured by the sonic anemometer if a low-pass filter with a cut...

Field Observations of Coastal Air-Sea Interaction

Science.gov (United States)

Ortiz-Suslow, D. G.; Haus, B. K.; Williams, N. J.; Graber, H. C.

2016-12-01

In the nearshore zone wind, waves, and currents generated from different forcing mechanisms converge in shallow water. This can profoundly affect the physical nature of the ocean surface, which can significantly modulate the exchange of momentum, heat, and mass across the air-sea interface. For decades, the focus of air-sea interaction research has been on the open ocean while the shallow water regime has been relatively under-explored. This bears implications for efforts to understand and model various coastal processes, such as mixing, surface transport, and air-sea gas flux. The results from a recent study conducted at the New River Inlet in North Carolina showed that directly measured air-sea flux parameters, such as the atmospheric drag coefficient, are strong functions of space as well as the ambient conditions (i.e. wind speed and direction). The drag is typically used to parameterize the wind stress magnitude. It is generally assumed that the wind direction is the direction of the atmospheric forcing (i.e. wind stress), however significant wind stress steering off of the azimuthal wind direction was observed and was found to be related to the horizontal surface current shear. The authors have just returned from a field campaign carried out within Monterey Bay in California. Surface observations made from two research vessels were complimented by an array of beach and inland flux stations, high-resolution wind forecasts, and satellite image acquisitions. This is a rich data set and several case studies will be analyzed to highlight the importance of various processes for understanding the air-sea fluxes. Preliminary findings show that interactions between the local wind-sea and the shoaling, incident swell can have a profound effect on the wind stress magnitude. The Monterey Bay coastline contains a variety of topographical features and the importance of land-air-sea interactions will also be investigated.

A directional passive air sampler for monitoring polycyclic aromatic hydrocarbons (PAHs) in air mass

International Nuclear Information System (INIS)

Tao, S.; Liu, Y.N.; Lang, C.; Wang, W.T.; Yuan, H.S.; Zhang, D.Y.; Qiu, W.X.; Liu, J.M.; Liu, Z.G.; Liu, S.Z.; Yi, R.; Ji, M.; Liu, X.X.

2008-01-01

A passive air sampler was developed for collecting polycyclic aromatic hydrocarbons (PAHs) in air mass from various directions. The airflow velocity within the sampler was assessed for its responses to ambient wind speed and direction. The sampler was examined for trapped particles, evaluated quantitatively for influence of airflow velocity and temperature on PAH uptake, examined for PAH uptake kinetics, calibrated against active sampling, and finally tested in the field. The airflow volume passing the sampler was linearly proportional to ambient wind speed and sensitive to wind direction. The uptake rate for an individual PAH was a function of airflow velocity, temperature and the octanol-air partitioning coefficient of the PAH. For all PAHs with more than two rings, the passive sampler operated in a linear uptake phase for three weeks. Different PAH concentrations were obtained in air masses from different directions in the field test. - A novel directional passive air sampler was developed and tested for monitoring PAHs in air masses from different directions

Field evaluation of vegetation and noise barriers for mitigation of near-freeway air pollution under variable wind conditions

Science.gov (United States)

Lee, Eon S.; Ranasinghe, Dilhara R.; Ahangar, Faraz Enayati; Amini, Seyedmorteza; Mara, Steven; Choi, Wonsik; Paulson, Suzanne; Zhu, Yifang

2018-02-01

Traffic-related air pollutants are a significant public health concern, particularly near freeways. Previous studies have suggested either soundwall or vegetation barriers might reduce the near-freeway air pollution. This study aims to investigate the effectiveness of a combination of both soundwall and vegetation barrier for reducing ultrafine particles (UFPs, diameter ≤ 100 nm) and PM2.5 (diameter ≤ 2.5 μm) concentrations. Concurrent data collection was carried out at both upwind and downwind fixed locations approximately 10-15 m away from the edge of two major freeways in California. This study observed that the reduction of UFP and PM2.5 was generally greater with the combination barrier than with either soundwall or vegetation alone. Since there were no non-barrier sites at the study locations, the reductions reported here are all in relative terms. The soundwall barrier was more effective for reducing PM2.5 (25-53%) than UFPs (0-5%), and was most effective (51-53% for PM2.5) when the wind speed ranged between 1 and 2 m/s. Under the same range of wind speed, the vegetation barrier had little effect (0-5%) on reducing PM2.5; but was effective at reducing UFP (up to 50%). For both types of roadside barrier, decreasing wind speed resulted in greater net reduction of UFPs (i.e., total number particle concentrations; inversely proportional). This trend was observed, however, only within specific particle size ranges (i.e., diameter pollution mitigation.

The characteristic of gap FBG and its application

Science.gov (United States)

Yang, Yuanhong; Hu, Jun; Liu, Xuejing; Jin, Wei

2015-07-01

A gap fiber Bragg grating (g-FBG) is fabricated by cutting a uniform FBG in the middle to introduce a small air gap between the two sections. Numerical and experimental investigations show that the g-FBG has the characteristics of both a phase shifted FBG and a Fizeau interferometer. The influence of the air-gap shift longitudinally or transversely with respect to the fiber central axis and temperature to g-FBG's spectrums are investigated with numerical simulation and experiments, and the mathematic models are made. Based on g-FBG's different sensitivity to gap width and temperature, a micro-gap and temperature simultaneous measurement sensor was demonstrated. And a g-FBG based tunable fiber ring laser with a narrow line-width is demonstrated.

Optimal design and control of solar driven air gap membrane distillation desalination systems

International Nuclear Information System (INIS)

Chen, Yih-Hang; Li, Yu-Wei; Chang, Hsuan

2012-01-01

Highlights: ► Air gap membrane distillation unit was used in the desalination plants. ► Aspen Custom Molder was used to simulate each unit of desalination plants. ► Design parameters were investigated to obtain the minimum total annual cost. ► The control structure was proposed to operate desalination plants all day long. -- Abstract: A solar heated membrane distillation desalination system is constructed of solar collectors and membrane distillation devices for increasing pure water productivity. This technically and economically feasible system is designed to use indirect solar heat to drive membrane distillation processes to overcome the unstable supply of solar radiation from sunrise to sunset. The solar heated membrane distillation desalination system in the present study consisted of hot water storage devices, heat exchangers, air gap membrane distillation units, and solar collectors. Aspen Custom Molder (ACM) software was used to model and simulate each unit and establish the cost function of a desalination plant. From Design degree of freedom (DOF) analysis, ten design parameters were investigated to obtain the minimum total annual cost (TAC) with fixed pure water production rate. For a given solar energy density profile of typical summer weather, the minimal TAC per 1 m 3 pure water production can be found at 500 W/m 2 by varying the solar energy intensity. Therefore, we proposed two modes for controlling the optimal design condition of the desalination plant; day and night. In order to widen the operability range of the plant, the sensitivity analysis was used to retrofit the original design point to lower the effluent temperature from the solar collector by increasing the hot water recycled stream. The simulation results show that the pure water production can be maintained at a very stable level whether in sunny or cloudy weather.

Effect of Air-Curtain Discharge Speed on the Effectiveness of Vortex-like Air-Curtain Approach for Severe Accident Management

International Nuclear Information System (INIS)

Ullah, Sana; Yim, Man Sung

2017-01-01

The purpose of air-curtain installation is to isolate reactor containment from outside environment, confine the leaking radioactive material in a localized area, and minimize the impact of outside wind. The wind could blow away airborne radioactive material immediately after discharge leaving little room for effective capturing. Therefore, vortex-like air-curtain plays an important role in this process, and its effectiveness could severely influence the performance of overall system. An approach based on vortex-like air-curtain was proposed earlier for preventing spread of radioactive material to the environment and mitigate subsequent radiological consequences. Effect of air-curtain discharge speed, and discharge angle was studied, and a quantitative account of air curtain in terms of effectiveness parameter was performed in this work. It was found that for given wind speed, air-curtain effectiveness would improve with increase in air-curtain discharge speed to an extent, after which any increase in discharge velicity could deteriorate the performance, due to imbalance between discharge and wind speed. Keeping air-curtain discharge at an angle of 15° opposite to the predominant flow direction is devised.

Wind direction dependent vertical wind shear and surface roughness parameter in two different coastal environments

International Nuclear Information System (INIS)

Bagavathsingh, A.; Srinivas, C.V.; Baskaran, R.; Venkatraman, B.; Sardar Maran, P.

2016-01-01

Atmospheric boundary layer parameters and surface layer parameterizations are important prerequisites for air pollution dispersion analysis. The turbulent flow characteristics vary at coastal and inland sites where the nuclear facilities are situated. Many pollution sources and their dispersion occur within the roughness sub layer in the lower atmosphere. In this study analysis of wind direction dependence vertical wind shear, surface roughness lengths and surface layer wind condition has been carried out at a coastal and the urban coastal site for the different wind flow regime. The differential response of the near coastal and inland urban site SBL parameters (wind shear, roughness length, etc) was examined as a function of wind direction

Wind power in Arctic regions

International Nuclear Information System (INIS)

Lundsager, P.; Ahm, P.; Madsen, B.; Krogsgaard, P.

1993-07-01

Arctic or semi-arctic regions are often endowed with wind resources adequate for a viable production of electricity from the wind. Only limited efforts have so far been spent to introduce and to demonstrate the obvious synergy of combining wind power technology with the problems and needs of electricity generation in Arctic regions. Several factors have created a gap preventing the wind power technology carrying its full role in this context, including a certain lack of familiarity with the technology on the part of the end-users, the local utilities and communities, and a lack of commonly agreed techniques to adapt the same technology for Arctic applications on the part of the manufacturers. This report is part of a project that intends to contribute to bridging this gap. The preliminary results of a survey conducted by the project are included in this report, which is a working document for an international seminar held on June 3-4, 1993, at Risoe National Laboratory, Denmark. Following the seminar a final report will be published. It is intended that the final report will serve as a basis for a sustained, international effort to develop the wind power potential of the Arctic and semi-arctic regions. The project is carried out by a project group formed by Risoe, PA Energy and BTM Consult. The project is sponsored by the Danish Energy Agency of the Danish Ministry of Energy through grant no. ENS-51171/93-0008. (au)

OW CCMP Ocean Surface Wind

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Cross-Calibrated Multi-Platform (CCMP) Ocean Surface Wind Vector Analyses (Atlas et al., 2011) provide a consistent, gap-free long-term time-series of monthly...

Natural convection heat transfer from a long heated vertical cylinder to an adjacent air gap of concentric and eccentric conditions

DEFF Research Database (Denmark)

Hosseini, R.; Kolaei, Alireza Rezania; Alipour, M.

2012-01-01

In this work, the natural convection heat transfer from a long vertical electrically heated cylinder to an adjacent air gap is experimentally studied. The aspect and diameter ratios of the cylinder are 55.56 and 6.33, respectively. The experimental measurements were obtained for a concentric cond...

Spatial evolution equation of wind wave growth

Institute of Scientific and Technical Information of China (English)

WANG; Wei; (王; 伟); SUN; Fu; (孙; 孚); DAI; Dejun; (戴德君)

2003-01-01

Based on the dynamic essence of air-sea interactions, a feedback type of spatial evolution equation is suggested to match reasonably the growing process of wind waves. This simple equation involving the dominant factors of wind wave growth is able to explain the transfer of energy from high to low frequencies without introducing the concept of nonlinear wave-wave interactions, and the results agree well with observations. The rate of wave height growth derived in this dissertation is applicable to both laboratory and open sea, which solidifies the physical basis of using laboratory experiments to investigate the generation of wind waves. Thus the proposed spatial evolution equation provides a new approach for the research on dynamic mechanism of air-sea interactions and wind wave prediction.

Waves in the Red Sea: Response to monsoonal and mountain gap winds

KAUST Repository

Ralston, David K.; Jiang, Houshuo; Farrar, J. Thomas

2013-01-01

An unstructured grid, phase-averaged wave model forced with winds from a high resolution atmospheric model is used to evaluate wind wave conditions in the Red Sea over an approximately 2-year period. The Red Sea lies in a narrow rift valley

The measured field performances of eight different mechanical and air-lift water-pumping wind-turbines

Energy Technology Data Exchange (ETDEWEB)

Kentfield, J.A.C. [Univ. of Calgary, Alberta (Canada)

1996-12-31

Results are presented of the specific performances of eight, different, water-pumping wind-turbines subjected to impartial tests at the Alberta Renewable Energy Test Site (ARETS), Alberta, Canada. The results presented which were derived from the test data, obtained independently of the equipment manufacturers, are expressed per unit of rotor projected area to eliminate the influence of machine size. Hub-height wind speeds and water flow rates for a common lift of 5.5 m (18 ft) constitute the essential test data. A general finding was that, to a first approximation, there were no major differences in specific performance between four units equipped with conventional reciprocating pumps two of which employed reduction gearing and two of which did not. It was found that a unit equipped with a Moyno pump performed well but three air-lift machines had, as was expected, poorer specific performances than the more conventional equipment. 10 refs., 9 figs.

Evaluation of air gap membrane distillation process running under sub-atmospheric conditions: Experimental and simulation studies

KAUST Repository

Alsaadi, Ahmad S.; Francis, Lijo; Maab, Husnul; Amy, Gary L.; Ghaffour, NorEddine

2015-01-01

The importance of removing non-condensable gases from air gap membrane distillation (AGMD) modules in improving the water vapor flux is presented in this paper. Additionally, a previously developed AGMD mathematical model is used to predict to the degree of flux enhancement under sub-atmospheric pressure conditions. Since the mathematical model prediction is expected to be very sensitive to membrane distillation (MD) membrane resistance when the mass diffusion resistance is eliminated, the permeability of the membrane was carefully measured with two different methods (gas permeance test and vacuum MD permeability test). The mathematical model prediction was found to highly agree with the experimental data, which showed that the removal of non-condensable gases increased the flux by more than three-fold when the gap pressure was maintained at the saturation pressure of the feed temperature. The importance of staging the sub-atmospheric AGMD process and how this could give better control over the gap pressure as the feed temperature decreases are also highlighted in this paper. The effect of staging on the sub-atmospheric AGMD flux and its relation to membrane capital cost are briefly discussed.

Evaluation of air gap membrane distillation process running under sub-atmospheric conditions: Experimental and simulation studies

KAUST Repository

Alsaadi, Ahmad S.

2015-04-16

The importance of removing non-condensable gases from air gap membrane distillation (AGMD) modules in improving the water vapor flux is presented in this paper. Additionally, a previously developed AGMD mathematical model is used to predict to the degree of flux enhancement under sub-atmospheric pressure conditions. Since the mathematical model prediction is expected to be very sensitive to membrane distillation (MD) membrane resistance when the mass diffusion resistance is eliminated, the permeability of the membrane was carefully measured with two different methods (gas permeance test and vacuum MD permeability test). The mathematical model prediction was found to highly agree with the experimental data, which showed that the removal of non-condensable gases increased the flux by more than three-fold when the gap pressure was maintained at the saturation pressure of the feed temperature. The importance of staging the sub-atmospheric AGMD process and how this could give better control over the gap pressure as the feed temperature decreases are also highlighted in this paper. The effect of staging on the sub-atmospheric AGMD flux and its relation to membrane capital cost are briefly discussed.

Evaluation of a micro-scale wind model's performance over realistic building clusters using wind tunnel experiments

Science.gov (United States)

Zhang, Ning; Du, Yunsong; Miao, Shiguang; Fang, Xiaoyi

2016-08-01

The simulation performance over complex building clusters of a wind simulation model (Wind Information Field Fast Analysis model, WIFFA) in a micro-scale air pollutant dispersion model system (Urban Microscale Air Pollution dispersion Simulation model, UMAPS) is evaluated using various wind tunnel experimental data including the CEDVAL (Compilation of Experimental Data for Validation of Micro-Scale Dispersion Models) wind tunnel experiment data and the NJU-FZ experiment data (Nanjing University-Fang Zhuang neighborhood wind tunnel experiment data). The results show that the wind model can reproduce the vortexes triggered by urban buildings well, and the flow patterns in urban street canyons and building clusters can also be represented. Due to the complex shapes of buildings and their distributions, the simulation deviations/discrepancies from the measurements are usually caused by the simplification of the building shapes and the determination of the key zone sizes. The computational efficiencies of different cases are also discussed in this paper. The model has a high computational efficiency compared to traditional numerical models that solve the Navier-Stokes equations, and can produce very high-resolution (1-5 m) wind fields of a complex neighborhood scale urban building canopy (~ 1 km ×1 km) in less than 3 min when run on a personal computer.

An Exploration of Wind Stress Calculation Techniques in Hurricane Storm Surge Modeling

Directory of Open Access Journals (Sweden)

Kyra M. Bryant

2016-09-01

Full Text Available As hurricanes continue to threaten coastal communities, accurate storm surge forecasting remains a global priority. Achieving a reliable storm surge prediction necessitates accurate hurricane intensity and wind field information. The wind field must be converted to wind stress, which represents the air-sea momentum flux component required in storm surge and other oceanic models. This conversion requires a multiplicative drag coefficient for the air density and wind speed to represent the air-sea momentum exchange at a given location. Air density is a known parameter and wind speed is a forecasted variable, whereas the drag coefficient is calculated using an empirical correlation. The correlation’s accuracy has brewed a controversy of its own for more than half a century. This review paper examines the lineage of drag coefficient correlations and their acceptance among scientists.

Wind potential assessment of Quebec Province

International Nuclear Information System (INIS)

Ilinca, A.; Chaumel, J.-L.; Retiveau, J.-L.

2003-01-01

The paper presents the development of a comprehensive wind atlas of the Province of Quebec. This study differs from previous studies by 1) use of a standard classification index to categorize the wind resource, 2) extensive review of surface and upper air data available for the Province to define the wind resource, and 3) integration of available wind data with the topography of the Province. The wind resource in the Province of Quebec is classified using the scheme proposed by Battelle-Pacific Northwest Laboratory (PNL). The Battelle-PNL classification is a numerical one which includes rankings from Wind Power Class 1 (lowest) to Wind Power Class 7 (highest). Associated with each numerical classification is a range of wind power and associated mean wind speed at 10 m and 50 m above ground level. For this study, a classification for 30 m above ground level was interpolated and used. A significant amount of wind data was gathered for the Province. These data were obtained from Atmospheric Environment Service (AES), Canada, from wind project developers, and from climatological summaries of surface and upper air data. A total of 35 primary data sites were selected in the Province. Although a number of wind data sites in the Province were identified and used in the analysis, large areas of the Province lacked any specific wind information. The Province was divided into grid blocks having dimensions of 1/4 o latitude by 1/3 o longitude. Each grid block is assigned a numerical Wind Power Class value ranging from 1 to 7. This value is based on the integration of the available wind data and the topography within the square. The majority of the Province was classified as 1 or 2. Coastal locations and topographic features in the interior of the Province typically have Wind Power Class 3 or higher. (author)

Air and water trade winds, hurricanes, gulf stream, tsunamis and other striking phenomena

CERN Document Server

Moreau, René

2017-01-01

Air and water are so familiar that we all think we know them. Yet how difficult it remains to predict their behavior, with so many questions butting against the limits of our knowledge. How are cyclones, tornadoes, thunderstorms, tsunamis or floods generated — sometimes causing devastation and death? What will the weather be tomorrow, next week, next summer? This book brings some answers to these questions with a strategy of describing before explaining. Starting by considering air and water in equilibrium (i.e., at rest), it progresses to discuss dynamic phenomena first focusing on large scale structures, such as El Niño or trade winds, then on ever smaller structures, such as low-pressure zones in the atmosphere, clouds, rain, as well as tides and waves. It finishes by describing man-mad e constructions (dams, ports, power plants, etc.) that serve to domesticate our water resources and put them to work for us.  Including over one hundred illustrations and very few equations, most of the�...

Mother Nature inspires new wind turbine wing

DEFF Research Database (Denmark)

Sønderberg Petersen, L.

2007-01-01

The sight of a bird of prey hanging immobile in the air while its wings continuously adjust themselves slightly in relation to the wind in order to keep the bird in the same position in the air, is a sight that most of us have admired, including the windenergy scientists at Risø DTU. They have...... started transferring the principle to wind turbine blades to make them adaptive...

Air Flow Modeling in the Wind Tunnel of the FHWA Aerodynamics Laboratory at Turner-Fairbank Highway Research Center

Energy Technology Data Exchange (ETDEWEB)

Sitek, M. A. [Argonne National Lab. (ANL), Argonne, IL (United States). Transportation Research and Analysis Computing Center (TRACC) Energy Systems Division; Lottes, S. A. [Argonne National Lab. (ANL), Argonne, IL (United States). Transportation Research and Analysis Computing Center (TRACC) Energy Systems Division; Bojanowski, C. [Argonne National Lab. (ANL), Argonne, IL (United States). Transportation Research and Analysis Computing Center (TRACC) Energy Systems Division

2017-09-01

geometry and CFD model of the wind tunnel laboratory at TFHRC was built and tested. Results were compared against experimental wind velocity measurements at a large number of locations around the room. This testing included an assessment of the air flow uniformity provided by the tunnel to the test zone and assessment of room geometry effects, such as influence of the proximity the room walls, the non-symmetrical position of the tunnel in the room, and the influence of the room setup on the air flow in the room. This information is useful both for simplifying the computational model and in deciding whether or not moving, or removing, some of the furniture or other movable objects in the room will change the flow in the test zone.

Investigation of the possible influence of wind turbines on birds

Energy Technology Data Exchange (ETDEWEB)

Winkelman, J E

1988-11-01

An overview is given of carried out and current field studies, results and gaps with regard to bird damage caused by wind turbines. Present research aims at disturbance of the environment, chances for birds to become victims and actual number of victims. Gaps in our knowledge exist in particular with regard to victims which fall at night. Investigation of the chances for birds to become victims at night is preferable to searching night victims by daylight because of minimal chances of finding them and high labour-intensity. In general it can be said that current field research at the relation between wind turbines and birds is site-oriented. Broader research, especially aimed at the disturbance aspect, is not possible right now, because large wind turbines and wind turbine arrays are rare. 3 figs., 7 refs., 5 tabs.

Guide to Using the WIND Toolkit Validation Code

Energy Technology Data Exchange (ETDEWEB)

Lieberman-Cribbin, W.; Draxl, C.; Clifton, A.

2014-12-01

In response to the U.S. Department of Energy's goal of using 20% wind energy by 2030, the Wind Integration National Dataset (WIND) Toolkit was created to provide information on wind speed, wind direction, temperature, surface air pressure, and air density on more than 126,000 locations across the United States from 2007 to 2013. The numerical weather prediction model output, gridded at 2-km and at a 5-minute resolution, was further converted to detail the wind power production time series of existing and potential wind facility sites. For users of the dataset it is important that the information presented in the WIND Toolkit is accurate and that errors are known, as then corrective steps can be taken. Therefore, we provide validation code written in R that will be made public to provide users with tools to validate data of their own locations. Validation is based on statistical analyses of wind speed, using error metrics such as bias, root-mean-square error, centered root-mean-square error, mean absolute error, and percent error. Plots of diurnal cycles, annual cycles, wind roses, histograms of wind speed, and quantile-quantile plots are created to visualize how well observational data compares to model data. Ideally, validation will confirm beneficial locations to utilize wind energy and encourage regional wind integration studies using the WIND Toolkit.

Advanced wind turbine with lift-destroying aileron for shutdown

Science.gov (United States)

Coleman, Clint; Juengst, Theresa M.; Zuteck, Michael D.

1996-06-18

An advanced aileron configuration for wind turbine rotors featuring an aileron with a bottom surface that slopes upwardly at an angle toward the nose region of the aileron. The aileron rotates about a center of rotation which is located within the envelope of the aileron, but does not protrude substantially into the air flowing past the aileron while the aileron is deflected to angles within a control range of angles. This allows for strong positive control of the rotation of the rotor. When the aileron is rotated to angles within a shutdown range of deflection angles, lift-destroying, turbulence-producing cross-flow of air through a flow gap, and turbulence created by the aileron, create sufficient drag to stop rotation of the rotor assembly. The profile of the aileron further allows the center of rotation to be located within the envelope of the aileron, at or near the centers of pressure and mass of the aileron. The location of the center of rotation optimizes aerodynamically and gyroscopically induced hinge moments and provides a fail safe configuration.

Air emissions due to wind and solar power.

Science.gov (United States)

Katzenstein, Warren; Apt, Jay

2009-01-15

Renewables portfolio standards (RPS) encourage large-scale deployment of wind and solar electric power. Their power output varies rapidly, even when several sites are added together. In many locations, natural gas generators are the lowest cost resource available to compensate for this variability, and must ramp up and down quickly to keep the grid stable, affecting their emissions of NOx and CO2. We model a wind or solar photovoltaic plus gas system using measured 1-min time-resolved emissions and heat rate data from two types of natural gas generators, and power data from four wind plants and one solar plant. Over a wide range of renewable penetration, we find CO2 emissions achieve approximately 80% of the emissions reductions expected if the power fluctuations caused no additional emissions. Using steam injection, gas generators achieve only 30-50% of expected NOx emissions reductions, and with dry control NOx emissions increase substantially. We quantify the interaction between state RPSs and NOx constraints, finding that states with substantial RPSs could see significant upward pressure on NOx permit prices, if the gas turbines we modeled are representative of the plants used to mitigate wind and solar power variability.

Understanding wind power technology theory, deployment and optimisation

CERN Document Server

Schaffarczyk, Alois

2014-01-01

Wind energy technology has progressed enormously over the last decade. In coming years it will continue to develop in terms of power ratings, performance and installed capacity of large wind turbines worldwide, with exciting developments in offshore installations. Designed to meet the training needs of wind engineers, this introductory text puts wind energy in context, from the natural resource to the assessment of cost effectiveness and bridges the gap between theory and practice. The thorough coverage spans the scientific basics, practical implementations and the modern state of technology

Measurement of volatile organic compounds during start-up of bioremediation of French limited superfund site in Crosby Texas using wind dependent whole-air sampling

International Nuclear Information System (INIS)

Pleil, J.D.; Fortune, C.R.; Yoong, M.; Oliver, K.D.

1993-01-01

Whole-air sampling was performed before and after the start-up of the bioremediation of an industrial (primarily petrochemical) waste lagoon in Crosby Texas, near Houston. Four 'Sector Samplers' were deployed at the four corners of the French Limited Superfund Site. These samplers collect air into one of two SUMMA polished canisters depending upon wind direction and speed. When the wind blows at the sampler from across the waste lagoon, air is routed to the 'IN' sector canister, otherwise sample is collected in the 'OUT' sector canister. As such, each sampler provides its own background sample, and, upon gas chromatographic analysis, individual compounds can be associated with the waste lagoon. Five sets of 24-hour sector samples were taken; the first set was collected prior to the start of the bioremediation effort and the remaining four sets were taken sequentially for four 24-hour periods after the start-up of the procedure

Behavior of bats at wind turbines.

Science.gov (United States)

Cryan, Paul M; Gorresen, P Marcos; Hein, Cris D; Schirmacher, Michael R; Diehl, Robert H; Huso, Manuela M; Hayman, David T S; Fricker, Paul D; Bonaccorso, Frank J; Johnson, Douglas H; Heist, Kevin; Dalton, David C

2014-10-21

Wind turbines are causing unprecedented numbers of bat fatalities. Many fatalities involve tree-roosting bats, but reasons for this higher susceptibility remain unknown. To better understand behaviors associated with risk, we monitored bats at three experimentally manipulated wind turbines in Indiana, United States, from July 29 to October 1, 2012, using thermal cameras and other methods. We observed bats on 993 occasions and saw many behaviors, including close approaches, flight loops and dives, hovering, and chases. Most bats altered course toward turbines during observation. Based on these new observations, we tested the hypotheses that wind speed and blade rotation speed influenced the way that bats interacted with turbines. We found that bats were detected more frequently at lower wind speeds and typically approached turbines on the leeward (downwind) side. The proportion of leeward approaches increased with wind speed when blades were prevented from turning, yet decreased when blades could turn. Bats were observed more frequently at turbines on moonlit nights. Taken together, these observations suggest that bats may orient toward turbines by sensing air currents and using vision, and that air turbulence caused by fast-moving blades creates conditions that are less attractive to bats passing in close proximity. Tree bats may respond to streams of air flowing downwind from trees at night while searching for roosts, conspecifics, and nocturnal insect prey that could accumulate in such flows. Fatalities of tree bats at turbines may be the consequence of behaviors that evolved to provide selective advantages when elicited by tall trees, but are now maladaptive when elicited by wind turbines.

Behavior of bats at wind turbines

Science.gov (United States)

Cryan, Paul M.; Gorresen, P. Marcos; Hine, Cris D.; Schirmacher, Michael; Diehl, Robert H.; Huso, Manuela M.; Hayman, David T.S.; Fricker, Paul D.; Bonaccorso, Frank J.; Johnson, Douglas H.; Heist, Kevin W.; Dalton, David C.

2014-01-01

Wind turbines are causing unprecedented numbers of bat fatalities. Many fatalities involve tree-roosting bats, but reasons for this higher susceptibility remain unknown. To better understand behaviors associated with risk, we monitored bats at three experimentally manipulated wind turbines in Indiana, United States, from July 29 to October 1, 2012, using thermal cameras and other methods. We observed bats on 993 occasions and saw many behaviors, including close approaches, flight loops and dives, hovering, and chases. Most bats altered course toward turbines during observation. Based on these new observations, we tested the hypotheses that wind speed and blade rotation speed influenced the way that bats interacted with turbines. We found that bats were detected more frequently at lower wind speeds and typically approached turbines on the leeward (downwind) side. The proportion of leeward approaches increased with wind speed when blades were prevented from turning, yet decreased when blades could turn. Bats were observed more frequently at turbines on moonlit nights. Taken together, these observations suggest that bats may orient toward turbines by sensing air currents and using vision, and that air turbulence caused by fast-moving blades creates conditions that are less attractive to bats passing in close proximity. Tree bats may respond to streams of air flowing downwind from trees at night while searching for roosts, conspecifics, and nocturnal insect prey that could accumulate in such flows. Fatalities of tree bats at turbines may be the consequence of behaviors that evolved to provide selective advantages when elicited by tall trees, but are now maladaptive when elicited by wind turbines.

Cost-effective Design and Operation of Variable Speed Wind Turbines. Closing the Gap between the Control Engineering and the Wind Engineering Community

Energy Technology Data Exchange (ETDEWEB)

Molenaar, D.P.

2003-02-18

Wind has the potential to play a more important role in the future world electricity supply, provided that the cost per kilowatt hour is further reduced. The cost of wind-generated electricity can be effectively reduced by improvements in both wind turbine design and operation. In this thesis a design tool has been developed that offers the possibility to generate accurate and reliable dynamic models of the complete wind turbine. The models can be either used to evaluate the impact that design choices have on the economic viability, or to assess the dynamic behavior of the selected wind turbine configuration under various conditions.

Experimental method to reveal the effect of rotor magnet size and air gap on artificial heart driving motor torque and efficiency.

Science.gov (United States)

Qian, K X; Yuan, H Y; Ru, W M; Zeng, P

2002-01-01

To investigate experimentally the effect of rotor magnet design on artificial heart driving motor performance, seven rotors with different magnet lengths or thicknesses, as well as different peripheral angles, were manufactured and tested in the same motor stator with different rotating speeds. The input power (voltage and current) and output torque were measured and the motor efficiency was computed. The results demonstrated that the reduction of rotor magnet size and the enlargement of the air gap between the rotor magnets and the stator coil core have no significant effect on motor efficiency, but will reduce the torque value on which the motor achieves the highest efficiency; it could be remedied however by increasing the rotating speed, because the torque at the high efficiency point will increase along with the rotating speed. These results may provide a basis for developing small rotor magnets, large air gap and high efficiency motors for driving an artificial heart pump.

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...

Gone with the wind? The impact of wind turbines on tourism demand

International Nuclear Information System (INIS)

Broekel, Tom; Alfken, Christoph

2015-01-01

While wind energy production is relatively free from environmental externalities such as air pollution, it is frequently considered to negatively impact landscapes' visual aesthetic values, thereby inducing negative effects on tourism demand. Existing evidence for Germany indeed points towards a negative relationship between tourism demand and wind turbine construction. However, the existing studies primarily rely on interview data and simple bivariate statistics. In contrast, we make use of secondary statistics on tourism and wind turbine locations at the level of German municipalities. Using spatial panel regression techniques, we confirm a negative relation between wind turbines around municipalities and tourism demand for municipalities not located near the coast. In the latter regions, the relation between wind turbines and tourism demand is more complex. - Highlights: • Comprehensive quantitative empirical study on wind turbines and tourism demand. • Consideration of wind turbines in vacation municipalities and in their geographic surroundings. • Novel data set on wind turbines and touristic demand in all German municipalities. • Application of spatial panel analysis in the context of tourism research. • Evidence for a negative relationship between wind turbines and tourism demand.

Numerical modeling of the thermoelectric cooler with a complementary equation for heat circulation in air gaps

Science.gov (United States)

Fang, En; Wu, Xiaojie; Yu, Yuesen; Xiu, Junrui

2017-03-01

In this paper, a numerical model is developed by combining thermodynamics with heat transfer theory. Taking inner and external multi-irreversibility into account, it is with a complementary equation for heat circulation in air gaps of a steady cooling system with commercial thermoelectric modules operating in refrigeration mode. With two modes concerned, the equation presents the heat flowing through air gaps which forms heat circulations between both sides of thermoelectric coolers (TECs). In numerical modelling, a TEC is separated as two temperature controlled constant heat flux reservoirs in a thermal resistance network. In order to obtain the parameter values, an experimental apparatus with a commercial thermoelectric cooler was built to characterize the performance of a TEC with heat source and sink assembly. At constant power dissipation, steady temperatures of heat source and both sides of the thermoelectric cooler were compared with those in a standard numerical model. The method displayed that the relationship between Φf and the ratio Φ_{c}'/Φ_{c} was linear as expected. Then, for verifying the accuracy of proposed numerical model, the data in another system were recorded. It is evident that the experimental results are in good agreement with simulation(proposed model) data at different heat transfer rates. The error is small and mainly results from the instabilities of thermal resistances with temperature change and heat flux, heat loss of the device vertical surfaces and measurements.

Design procedure for a wind-wheel with self-adjusting blade mechanism

Directory of Open Access Journals (Sweden)

Gennady A. Oborsky

2014-12-01

Full Text Available Developed is a wind-wheel design equipped with the self-adjusting blade. The blade is positioned eccentrically to the balance wheel and can freely rotate around its axis. Elaborated is the method of calculating the energy characteristics for a wind-wheel with the self-adjusting blade, considering not only the wind force but the force of air counter flow resistance to the blade’s rotation. Initially, the blade being located at an angle α = 45 to the wheel rotation plane, the air flow rotates the wheel with the maximum force. Thus, the speed of rotation increases that involves the increase in air counter flow resistance and results in blade turning with respective angle α reduction. This, consequently, reduces the torque. When the torsional force and the resistance enter into equilibrium, the blade takes a certain angle α, and the wheel speed becomes constant. This wind-wheel design including a self-adjusting blade allows increasing the air flow load ratio when compared to the wind-wheel equipped with a jammed blade.

Wind energy potential in Peshawar, Pakistan

International Nuclear Information System (INIS)

Nasir, S.M.; Raza, S.M.

1994-01-01

Hourly wind data at Peshawar airport, received from the Headquarters, Pakistan Air Force, has been used to determine the diurnal variations, speed duration and speed frequency curves. The applicability of Weibull distribution is then tested over probability density function, which shows that weibull distribution fits the wind data satisfactorily and with a good precision, provided the observations of calm spells are omitted. Our analysis shows that monthly mean wind speed and wind power varies from 0.6 to 2.0 m/s and 0.2 to 4.0 wm-2, respectively, giving fair prospects for wind owe applications over the summer months. (author)

CFD simulation research on residential indoor air quality.

Science.gov (United States)

Yang, Li; Ye, Miao; He, Bao-Jie

2014-02-15

Nowadays people are excessively depending on air conditioning to create a comfortable indoor environment, but it could cause some health problems in a long run. In this paper, wind velocity field, temperature field and air age field in a bedroom with wall-hanging air conditioning running in summer are analyzed by CFD numerical simulation technology. The results show that wall-hanging air conditioning system can undertake indoor heat load and conduct good indoor thermal comfort. In terms of wind velocity, air speed in activity area where people sit and stand is moderate, most of which cannot feel wind flow and meet the summer indoor wind comfort requirement. However, for air quality, there are local areas without ventilation and toxic gases not discharged in time. Therefore it is necessary to take effective measures to improve air quality. Compared with the traditional measurement method, CFD software has many advantages in simulating indoor environment, so it is hopeful for humans to create a more comfortable, healthy living environment by CFD in the future. Copyright © 2013 Elsevier B.V. All rights reserved.

Design Considerations of a Transverse Flux Machine for Direct-Drive Wind Turbine Applications: Preprint

Energy Technology Data Exchange (ETDEWEB)

Husain, Tausif; Hasan, Iftekhar; Sozer, Yilmaz; Husain, Iqbal; Muljadi, Eduard

2017-01-01

This paper presents the design considerations of a double-sided transverse flux machine (TFM) for direct-drive wind turbine applications. The TFM has a modular structure with quasi-U stator cores and ring windings. The rotor is constructed with ferrite magnets in a flux-concentrating arrangement to achieve high air gap flux density. The design considerations for this TFM with respect to initial sizing, pole number selection, key design ratios, and pole shaping are presented in this paper. Pole number selection is critical in the design process of a TFM because it affects both the torque density and power factor under fixed magnetic and changing electrical loading. Several key design ratios are introduced to facilitate the design procedure. The effect of pole shaping on back-emf and inductance is also analyzed. These investigations provide guidance toward the required design of a TFM for direct-drive applications. The analyses are carried out using analytical and three-dimensional finite element analysis. A prototype is under construction for experimental verification.

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.;

Wind tunnel experimental study on effect of inland nuclear power plant cooling tower on air flow and dispersion of pollutant

International Nuclear Information System (INIS)

Qiao Qingdang; Yao Rentai; Guo Zhanjie; Wang Ruiying; Fan Dan; Guo Dongping; Hou Xiaofei; Wen Yunchao

2011-01-01

A wind tunnel experiment for the effect of the cooling tower at Taohuajiang nuclear power plant on air flow and dispersion of pollutant was introduced in paper. Measurements of air mean flow and turbulence structure in different directions of cooling tower and other buildings were made by using an X-array hot wire probe. The effects of the cooling tower and its drift on dispersion of pollutant from the stack were investigated through tracer experiments. The results show that the effect of cooling tower on flow and dispersion obviously depends on the relative position of stack to cooling towers, especially significant for the cooling tower parallel to stack along wind direction. The variation law of normalized maximum velocity deficit and perturbations in longitudinal turbulent intensity in cooling tower wake was highly in accordance with the result of isolated mountain measured by Arya and Gadiyaram. Dispersion of pollutant in near field is significantly enhanced and plume trajectory is changed due to the cooling towers and its drift. Meanwhile, the effect of cooling tower on dispersion of pollutant depends on the height of release. (authors)

Simulation of wind loads on facades - Out in the wind; Simulation von Windlasten auf Fassaden. Vom Winde umstroemt

Energy Technology Data Exchange (ETDEWEB)

Menti, U.-P.; Pluess, I.

2007-07-01

This illustrated article discusses the wind loads experienced by buildings at exposed locations and, in particular, the correct design of their facades. The various numerical methods such as computational fluid dynamics (CFD) available for this purpose are introduced and explained. The validation of the models is discussed and the simulation of wind loads on the new revolving restaurant on the Hohe Kasten mountain in eastern Switzerland is looked at. Here winds with speeds of up to 250 km/h from various directions can be expected. Illustrations are provided of the results obtained. Practical results obtained from the simulations such as the design of the building's facades and the correct placing of air vents are presented and discussed.

Experimental study of improved HAWT performance in simulated natural wind by an active controlled multi-fan wind tunnel

Science.gov (United States)

Toshimitsu, Kazuhiko; Narihara, Takahiko; Kikugawa, Hironori; Akiyoshi, Arata; Kawazu, Yuuya

2017-04-01

The effects of turbulent intensity and vortex scale of simulated natural wind on performance of a horizontal axis wind turbine (HAWT) are mainly investigated in this paper. In particular, the unsteadiness and turbulence of wind in Japan are stronger than ones in Europe and North America in general. Hence, Japanese engineers should take account of the velocity unsteadiness of natural wind at installed open-air location to design a higher performance wind turbine. Using the originally designed five wind turbines on the basis of NACA and MEL blades, the dependencies of the wind frequency and vortex scale of the simulated natural wind are presented. As the results, the power coefficient of the newly designed MEL3-type rotor in the simulated natural wind is 130% larger than one in steady wind.

Wind profiling for a coherent wind Doppler lidar by an auto-adaptive background subtraction approach.

Science.gov (United States)

Wu, Yanwei; Guo, Pan; Chen, Siying; Chen, He; Zhang, Yinchao

2017-04-01

Auto-adaptive background subtraction (AABS) is proposed as a denoising method for data processing of the coherent Doppler lidar (CDL). The method is proposed specifically for a low-signal-to-noise-ratio regime, in which the drifting power spectral density of CDL data occurs. Unlike the periodogram maximum (PM) and adaptive iteratively reweighted penalized least squares (airPLS), the proposed method presents reliable peaks and is thus advantageous in identifying peak locations. According to the analysis results of simulated and actually measured data, the proposed method outperforms the airPLS method and the PM algorithm in the furthest detectable range. The proposed method improves the detection range approximately up to 16.7% and 40% when compared to the airPLS method and the PM method, respectively. It also has smaller mean wind velocity and standard error values than the airPLS and PM methods. The AABS approach improves the quality of Doppler shift estimates and can be applied to obtain the whole wind profiling by the CDL.

Gas heating dynamics during leader inception in long air gaps at atmospheric pressure

International Nuclear Information System (INIS)

Liu, Lipeng; Becerra, Marley

2017-01-01

The inception of leader discharges in long air gaps at atmospheric pressure is simulated with a thermo-hydrodynamic model and a detailed kinetic scheme for N 2 /O 2 /H 2 O mixtures. In order to investigate the effect of humidity, the kinetic scheme includes the most important reactions with the H 2 O molecule and its derivatives, resulting in a scheme with 45 species and 192 chemical reactions. The heating of a thin plasma channel in front of an anode electrode during the streamer to leader transition is evaluated with a detailed 1D radial model. The analysis includes the simulation of the corresponding streamer bursts, dark periods and aborted leaders that may occur prior to the inception of a propagating leader discharge. The simulations are performed using the time-varying discharge current in two laboratory discharge events of positive polarity reported in the literature as input. Excellent agreement between the simulated and the experimental time variation of the thermal radius for a 1 m rod-plate air gap discharge event reported in the literature has been found. The role of different energy transfer and loss mechanisms prior to the inception of a stable leader is also discussed. It is found that although a small percentage of water molecules can accelerate the vibrational-translational relaxation to some extent, this effect leads to a negligible temperature increase during the streamer-to-leader transition. It is also found that the gas temperature should significantly exceed 2000 K for the transition to lead to the inception of a propagating leader. Otherwise, the strong convection loss produced by the gas expansion during the transition causes a drop in the translational temperature below 2000 K, aborting the incepted leader. Furthermore, it is shown that the assumptions used by the widely-used model of Gallimberti do not hold when evaluating the streamer-to-leader transition. (paper)

Spots on electrodes and images of a gap during pulsed discharges in an inhomogeneous electric field at elevated pressures of air, nitrogen and argon

International Nuclear Information System (INIS)

Shao, Tao; Yang, Wenjin; Zhang, Cheng; Yan, Ping; Tarasenko, Victor F; Beloplotov, Dmitry V; Lomaev, Mikhail I; Sorokin, Dmitry A

2014-01-01

Pulsed discharge in a nonuniform electric field accompanied by the appearance of bright spots due to explosive electron emission on electrodes has been investigated. The experiments were carried out using three experimental setups, a voltage pulse duration at a matched load of 2 ns, 40 ns, and 130 ns, respectively. Data on the formation of electrode spots during diffuse discharges in tube-plate or needle-plate gap configurations filled with gases at elevated pressures (air, nitrogen and argon) were obtained. It was found that in the air and other gases, bright spots arise on the flat electrode, and on the negative polarity of the electrode with a small radius of curvature, during the direction change of the current through the gap and the increase of the voltage pulse duration. It was shown that at the positive polarity of the electrode with a small radius of curvature, bright spots on the flat electrode arise due to the participation of the dynamic displacement current in the gap conductance. (paper)

Organizational forms promoting wind power development. Organizational and legal evaluation, energy- and environmental analysis and socio-economic analysis of wind turbine location along railways

International Nuclear Information System (INIS)

1997-12-01

Modernization of the train material and transition from diesel-driven to el-driven trains result in reduced air pollution in Denmark. The purpose of this study is to define, concretize and compare organizational forms for use of wind power as the 'green' electric power for train operation. An investment into an wind turbine array with 500 kW wind turbines in roughness class 2 would be repaid in 7.9 year period. Air pollution abatement together with improved socio-economic structure due to growing employment would be achieved. Several models of 'green' electrification of the national railways are given, both for state- and privately owned wind power plants. (EG)

Determining the Probability of Violating Upper-Level Wind Constraints for the Launch of Minuteman Ill Ballistic Missiles At Vandenberg Air Force Base

Science.gov (United States)

Shafer, Jaclyn A.; Brock, Tyler M.

2013-01-01

The 30th Operational Support Squadron Weather Flight (30 OSSWF) provides comprehensive weather services to the space program at Vandenberg Air Force Base (VAFB) in California. One of their responsibilities is to monitor upper-level winds to ensure safe launch operations of the Minuteman Ill ballistic missile. The 30 OSSWF requested the Applied Meteorology Unit (AMU) analyze VAFB sounding data to determine the probability of violating (PoV) upper-level thresholds for wind speed and shear constraints specific to this launch vehicle, and to develop a graphical user interface (GUI) that will calculate the PoV of each constraint on the day of launch. The AMU suggested also including forecast sounding data from the Rapid Refresh (RAP) model. This would provide further insight for the launch weather officers (LWOs) when determining if a wind constraint violation will occur over the next few hours, and help to improve the overall upper winds forecast on launch day.

Improved ADRC for a Maglev Planar Motor with a Concentric Winding Structure

Directory of Open Access Journals (Sweden)

Baoquan Kou

2016-12-01

Full Text Available In the semiconductor industry, positioning accuracy and acceleration are critical parameters. To improve the acceleration speed of a motor, this paper proposes the moving-coil maglev planar motor with a concentric winding structure. The coordinate system has been built for the multiple degrees of freedom movement system. The Lorenz force method has been applied to solve its electromagnetic model. The real-time solving of the generalized inverse matrix of factors can realize the decoupling of the winding current. When the maglev height changes, the electromagnetic force and torque decreases exponentially with the increase of the air gap. To decrease the influence on control system performance by the internal model change and the external disturbance, this paper proposes an improved active disturbance rejection control (ADRC to design the controller. This new controller overcomes the jitter phenomenon due to the turning point for the traditional ADRC, thus it is more suitable for the maglev control system. The comparison between ADRC and the improved ADRC has been conducted, the result of which shows the improved ADRC has greater robustness.

Onshore Wind Speed Modulates Microbial Aerosols along an Urban Waterfront

Directory of Open Access Journals (Sweden)

M. Elias Dueker

2017-11-01

Full Text Available Wind blowing over aquatic and terrestrial surfaces produces aerosols, which include microbial aerosols. We studied the effect of onshore wind speeds on aerosol concentrations as well as total and culturable microbial aerosols (bacterial and viral at an urban waterfront (New York, NY, United States of America. We used two distinct methods to characterize microbial aerosol responses to wind speed: A culture-based exposure-plate method measuring viable bacterial deposition near-shore (CFU accumulation rate; and a culture-independent aerosol sampler-based method measuring total bacterial and viral aerosols (cells m−3 air. While ambient coarse (>2 µm and fine (0.3–2 µm aerosol particle number concentrations (regulated indicators of air quality decreased with increasing onshore wind speeds, total and depositing culturable bacterial aerosols and total viral aerosols increased. Taxonomic identification of the 16S rDNA of bacterial aerosol isolates suggested both terrestrial and aquatic sources. Wind appears to increase microbial aerosol number concentrations in the near-shore environment by onshore transport at low wind speeds (<4 m s−1, and increased local production and transport of new microbial aerosols from adjacent water surfaces at higher wind speeds (>4 m s−1. This study demonstrates a wind-modulated microbial connection between water and air in the coastal urban environment, with implications for public health management and urban microbial ecology.

Coastal and rain-induced wind variability depicted by scatterometers

Science.gov (United States)

Portabella, M.; Lin, W.; Stoffelen, A.; Turiel, A.; Verhoef, A.; Verspeek, J.; Ballabrera, J.; Vogelzang, J.

2012-04-01

A detailed knowledge of local wind variability near the shore is very important since it strongly affects the weather and microclimate in coastal regions. Since coastal areas are densely populated and most activity at sea occurs near the shore, sea-surface wind field information is important for a number of applications. In the vicinity of land sea-breeze, wave fetch, katabatic and current effects are more likely than in the open ocean, thus enhancing air-sea interaction. Also very relevant for air-sea interaction are the rain-induced phenomena, such as downbursts and convergence. Relatively cold and dry air is effectively transported to the ocean surface and surface winds are enhanced. In general, both coastal and rain-induced wind variability are poorly resolved by Numerical Weather Prediction (NWP) models. Satellite real aperture radars (i.e., scatterometers) are known to provide accurate mesoscale (25-50 km resolution) sea surface wind field information used in a wide variety of applications. Nowadays, there are two operating scatterometers in orbit, i.e., the C-band Advanced Scatterometer (ASCAT) onboard Metop-A and the Ku-band scatterometer (OSCAT) onboard Oceansat-2. The EUMETSAT Ocean and Sea Ice Satellite Application Facility (OSI SAF) delivers several ASCAT level 2 wind products with 25 km and 12.5 km Wind Vector Cell (WVC) spacing, including a pre-operational coastal wind product as well as an OSCAT level 2 wind product with 50 km spacing in development status. Rain is known to both attenuate and scatter the microwave signal. In addition, there is a "splashing" effect. The roughness of the sea surface is increased because of splashing due to rain drops. The so-called "rain contamination" is larger for Ku-band scatterometer systems than for C-band systems. Moreover, the associated downdrafts lead to variable wind speeds and directions, further complicating the wind retrieval. The C-band ASCAT high resolution wind processing is validated under rainy

Small wind rising? Is the market for building-mounted wind power about to pick up?

International Nuclear Information System (INIS)

Slowe, J.

2006-01-01

The potential market for small roof-mounted wind turbines is discussed. Should the technology prove popular, the market would be enormous. Delta Energy and Environment has prepared a study called, Roof Top Wind Turbines: A Product for Mass Markets? At present, the future for roof-mounted wind turbines is unclear: predictions range from little or no market at all to mass installations with a payback period of as little as five years. Several small roof-top turbines are described. A critical factor influencing the efficiency of a roof-mounted wind turbine is the air flow pattern over the roof which may in turn be affected by neighbouring buildings. (author)

Wind Tunnel Modeling Of Wind Flow Over Complex Terrain

Science.gov (United States)

Banks, D.; Cochran, B.

2010-12-01

This presentation will describe the finding of an atmospheric boundary layer (ABL) wind tunnel study conducted as part of the Bolund Experiment. This experiment was sponsored by Risø DTU (National Laboratory for Sustainable Energy, Technical University of Denmark) during the fall of 2009 to enable a blind comparison of various air flow models in an attempt to validate their performance in predicting airflow over complex terrain. Bohlund hill sits 12 m above the water level at the end of a narrow isthmus. The island features a steep escarpment on one side, over which the airflow can be expected to separate. The island was equipped with several anemometer towers, and the approach flow over the water was well characterized. This study was one of only two only physical model studies included in the blind model comparison, the other being a water plume study. The remainder were computational fluid dynamics (CFD) simulations, including both RANS and LES. Physical modeling of air flow over topographical features has been used since the middle of the 20th century, and the methods required are well understood and well documented. Several books have been written describing how to properly perform ABL wind tunnel studies, including ASCE manual of engineering practice 67. Boundary layer wind tunnel tests are the only modelling method deemed acceptable in ASCE 7-10, the most recent edition of the American Society of Civil Engineers standard that provides wind loads for buildings and other structures for buildings codes across the US. Since the 1970’s, most tall structures undergo testing in a boundary layer wind tunnel to accurately determine the wind induced loading. When compared to CFD, the US EPA considers a properly executed wind tunnel study to be equivalent to a CFD model with infinitesimal grid resolution and near infinite memory. One key reason for this widespread acceptance is that properly executed ABL wind tunnel studies will accurately simulate flow separation

An aerodynamic noise propagation model for wind turbines

DEFF Research Database (Denmark)

Zhu, Wei Jun; Sørensen, Jens Nørkær; Shen, Wen Zhong

2005-01-01

A model based on 2-D sound ray theory for aerodynamic noise propagation from wind turbine rotating blades is introduced. The model includes attenuation factors from geometric spreading, sound directivity of source, air absorption, ground deflection and reflection, as well as effects from temperat......A model based on 2-D sound ray theory for aerodynamic noise propagation from wind turbine rotating blades is introduced. The model includes attenuation factors from geometric spreading, sound directivity of source, air absorption, ground deflection and reflection, as well as effects from...... temperature and airflow. At a given receiver point, the sound pressure is corrected by taking into account these propagation effects. As an overall assumption, the noise field generated by the wind turbine is simplified as a point source placed at the hub height of the wind turbine. This assumtion...... is reasonable, for the receiver is located in the far field, at distances from the wind turbine that are much longer than the diameter of the rotor....

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.

Wind versus Biofuels for Addressing Climate, Health, and Energy

International Nuclear Information System (INIS)

Jacobson, Mark Z.

2007-01-01

The favored approach today for addressing global warming is to promote a variety of options: biofuels, wind, solar thermal, solar photovoltaic, geothermal, hydroelectric, and nuclear energy and to improve efficiency. However, by far, most emphasis has been on biofuels. It is shown here, though, that current-technology biofuels cannot address global warming and may slightly increase death and illness due to ozone-related air pollution. Future biofuels may theoretically slow global warming, but only temporarily and with the cost of increased air pollution mortality. In both cases, the land required renders biofuels an impractical solution. Recent measurements and statistical analyses of U.S. and world wind power carried out at Stanford University suggest that wind combined with other options can substantially address global warming, air pollution mortality, and energy needs simultaneously.

Evaluation of Wind Energy Potential in Zaria Metropolis

African Journals Online (AJOL)

Keywords: Wind, Extractible Energy, Speed, Power. 41 ... wind results from the movement of air masses and arises primarily due to ... rotation is reclaimed at an angle of 23.5 to the plane in which it ... The power (P ) available in a free flowing wind of a a given cross ..... use and electricity generation: A life-cycle analysis.

Mexico Wind Resource Assessment Project

Energy Technology Data Exchange (ETDEWEB)

Schwartz, M.N.; Elliott, D.L.

1995-05-01

A preliminary wind energy resource assessment of Mexico that produced wind resource maps for both utility-scale and rural applications was undertaken as part of the Mexico-U.S. Renewable Energy Cooperation Program. This activity has provided valuable information needed to facilitate the commercialization of small wind turbines and windfarms in Mexico and to lay the groundwork for subsequent wind resource activities. A surface meteorological data set of hourly data in digital form was utilized to prepare a more detailed and accurate wind resource assessment of Mexico than otherwise would have been possible. Software was developed to perform the first ever detailed analysis of the wind characteristics data for over 150 stations in Mexico. The hourly data set was augmented with information from weather balloons (upper-air data), ship wind data from coastal areas, and summarized wind data from sources in Mexico. The various data were carefully evaluated for their usefulness in preparing the wind resource assessment. The preliminary assessment has identified many areas of good-to-excellent wind resource potential and shows that the wind resource in Mexico is considerably greater than shown in previous surveys.

The (R)evolution of China: Offshore Wind Diffusion

DEFF Research Database (Denmark)

Poulsen, Thomas; Hasager, Charlotte Bay

2017-01-01

This research presents an industry level gap analysis for Chinese offshore wind, which serves as a way to illuminate how China may fast track industry evolution. The research findings provide insight into how the Chinese government strongly and systematically decrees state-owned Chinese firms...... successfully forge long-term alliances also for future Chinese wind energy export projects. Examples of past efforts of collaboration not yielding desired results have been included as well. At policy level, recommendations are provided on how the evolution of the Chinese offshore wind power industry can...... be fast-tracked to mirror the revolutionary pace, volume, and velocity which the Chinese onshore wind power industry has mustered....

Teaching Air Pollution in an Authentic Context

Science.gov (United States)

Mandrikas, Achilleas; Stavrou, Dimitrios; Skordoulis, Constantine

2017-04-01

This paper describes a teaching-learning sequence (TLS) about air pollution and the findings resulting from its implementation by pre-service elementary teachers (PET) currently undergraduate students of the Department of Primary Education in the National and Kapodistrian University of Athens, Greece. The TLS focused on the relation of air pollution with wind and topography in local conditions. An authentic context was provided to the students based on daily up-to-date meteorological data via the Internet in order to estimate air pollution. The results are encouraging given that PET can correlate wind and concentration of air pollutants through reading specialized angular diagrams and weather maps, can recognize the correlation of topography in the concentration of air pollutants, and can describe temperature inversion. However, the PET demonstrated clear difficulties in ability of orientation, in wind naming, and in interpretation of symbols on weather map. Finally, the implications on teaching air pollution are discussed.

Impact of wind velocity on the performance of the RVACS decay heat removal system

International Nuclear Information System (INIS)

Tzanos, C.P.

1997-01-01

The impact of wind velocity on the performance of the reactor vessel auxiliary cooling system (RVACS) of an advanced liquid-metal reactor design is analyzed, and design modifications that mitigate adverse wind effects are investigated. In the reference design, the reactor is served by four communicating RVACS stacks, and each stack has two air inlets. In this two-inlet stack design, winds blowing in a direction 90 deg from the axis formed by the two stack inlets result in pressure distributions around the stacks that drastically change the desired airflow pattern in the RVACS. This leads to significantly elevated RVACS air temperatures and significant azimuthal guard vessel temperature variations. For example, a 27 m/s (60 mph) wind leads to an air temperature at the exit of the RVACS heated section that is ∼115 C higher than that under no-wind conditions. The addition of two more inlets per stack, one inlet per stack side, significantly improves RVACS performance. The air temperature at the exit of the heated RVACS section is significantly reduced below that of the two-inlet design, and this temperature decreases as the wind speed increases. An increase in wind speed from 3 to 27 m/s leads to an air temperature change from 186 to 165 C. The azimuthal temperature variation is also improved. At the top of the guard vessel, this variation is reduced from 62.5 to 8.5 C at the low wind speed of 3 m/s and from 85.0 to 30.5 C at the high wind speed of 27 m/s

IMPER: Characterization of the wind field over a large wind turbine rotor - final report; Improved performance

Energy Technology Data Exchange (ETDEWEB)

Schmidt Paulsen, U.; Wagner, R.

2012-01-15

A modern wind turbine rotor with a contemporary rotor size would easily with the tips penetrate the air between 116 m and 30 m and herby experience effects of different wind. With current rules on power performance measurements such as IEC 61400-121 the reference wind speed is measured at hub height, an oversimplification of the wind energy power over the rotor disk area is carried out. The project comprised a number of innovative and coordinated measurements on a full scale turbine with remote sensing technology and simulations on a 500 kW wind turbine for the effects of wind field characterization. The objective with the present report is to give a short overview of the different experiments carried out and results obtained within the final phase of this project. (Author)

Scheduling whole-air samples above the Trade Wind Inversion from SUAS using real-time sensors

Science.gov (United States)

Freer, J. E.; Greatwood, C.; Thomas, R.; Richardson, T.; Brownlow, R.; Lowry, D.; MacKenzie, A. R.; Nisbet, E. G.

2015-12-01

Small Unmanned Air Systems (SUAS) are increasingly being used in science applications for a range of applications. Here we explore their use to schedule the sampling of air masses up to 2.5km above ground using computer controlled bespoked Octocopter platforms. Whole-air sampling is targeted above, within and below the Trade Wind Inversion (TWI). On-board sensors profiled the TWI characteristics in real time on ascent and, hence, guided the altitudes at which samples were taken on descent. The science driver for this research is investigation of the Southern Methane Anomaly and, more broadly, the hemispheric-scale transport of long-lived atmospheric tracers in the remote troposphere. Here we focus on the practical application of SUAS for this purpose. Highlighting the need for mission planning, computer control, onboard sensors and logistics in deploying such technologies for out of line-of-sight applications. We show how such a platform can be deployed successfully, resulting in some 60 sampling flights within a 10 day period. Challenges remain regarding the deployment of such platforms routinely and cost-effectively, particularly regarding training and support. We present some initial results from the methane sampling and its implication for exploring and understanding the Southern Methane Anomaly.

Wind Farm Wake: The 2016 Horns Rev Photo Case

Directory of Open Access Journals (Sweden)

Charlotte Bay Hasager

2017-03-01

Full Text Available Offshore wind farm wakes were observed and photographed in foggy conditions at Horns Rev 2 on 25 January 2016 at 12:45 UTC. These new images show highly contrasting conditions regarding the wind speed, turbulence intensity, atmospheric stability, weather conditions and wind farm wake development as compared to the Horns Rev 1 photographs from 12 February 2008. The paper examines the atmospheric conditions from satellite images, radiosondes, lidar and wind turbine data and compares the observations to results from atmospheric meso-scale modelling and large eddy simulation. Key findings are that a humid and warm air mass was advected from the southwest over cold sea and the dew-point temperature was such that cold-water advection fog formed in a shallow layer. The flow was stably stratified and the freestream wind speed was 13 m/s at hub height, which means that most turbines produced at or near rated power. The wind direction was southwesterly and long, narrow wakes persisted several rotor diameters downwind of the wind turbines. Eventually mixing of warm air from aloft dispersed the fog in the far wake region of the wind farm.

Wind turbines - generating noise or electricity?

International Nuclear Information System (INIS)

Russell, Eric

1999-01-01

Wind turbine technology has made great strides in the past few years. Annual energy output is up by two orders of magnitude and nacelle weight and noise has been halved. Computational fluid dynamics has paid a part in advancing knowledge of air flow and turbulence around wind generators. Current research is focused on how to increase turbine size and improve efficiency. A problem is that while larger wind turbines will produce cheaper electricity, the noise problem will mean that the number of acceptable sites will decrease. The biggest wind generators will need about 800 m clearance from the nearest house. (UK)

Variation of air--water gas transfer with wind stress and surface viscoelasticity

OpenAIRE

Frew, Nelson M.; Bock, Erik J.; McGillis, Wade R.; Karachintsev, Andrey V.; Hara, Tetsu; Münsterer, Thomas; Jähne, Bernd

1995-01-01

Previous parameterizations of gas transfer velocity have attempted to cast this quantity as a function of wind speed or wind-stress. This study demonstrates that the presence of a surface film is effective at reducing the gas transfer velocity at constant wind-stress. Gas exchange experiments were performed at WHOI and UH using annular wind-wave tanks of different scales. Systematic variations of wind-stress and surfactant concentration (Triton-X-100) were explored to determ...

Meteorological and urban landscape factors on severe air pollution in Beijing.

Science.gov (United States)

Han, Lijian; Zhou, Weiqi; Li, Weifeng; Meshesha, Derege T; Li, Li; Zheng, Mingqing

2015-07-01

Air pollution gained special attention with the rapid development in Beijing. In January 2013, Beijing experienced extreme air pollution, which was not well examined. We thus examine the magnitude of air quality in the particular month by applying the air quality index (AQI), which is based on the newly upgraded Chinese environmental standard. Our finding revealed that (1) air quality has distinct spatial heterogeneity and relatively better air quality was observed in the northwest while worse quality happened in the southeast part of the city; (2) the wind speed is the main determinant of air quality in the city-when wind speed is greater than 4 m/sec, air quality can be significantly improved; and (3) urban impervious surface makes a contribution to the severity of air pollution-that is, with an increase in the fraction of impervious surface in a given area, air pollution is more severe. The results from our study demonstrated the severe pollution in Beijing and its meteorological and landscape factors. Also, the results of this work suggest that very strict air quality management should be conducted when wind speed less than 4 m/sec, especially at places with a large fraction of urban impervious surface. Prevention of air pollution is rare among methods with controls on meteorological and urban landscape conditions. We present research that utilizes the latest air quality index (AQI) to compare air pollution with meteorological and landscape conditions. We found that wind is the major meteorological factor that determines the air quality. For a given wind speed greater than 4 m/sec, the air quality improved significantly. Urban impervious surface also contributes to the severe air pollution: that is, when the fraction of impervious surface increases, there is more severe air pollution. These results suggest that air quality management should be conducted when wind speed is less than 4 m/sec, especially at places with a larger fraction of urban impervious surface.

Nonpolar III-nitride vertical-cavity surface-emitting laser with a photoelectrochemically etched air-gap aperture

Energy Technology Data Exchange (ETDEWEB)

Leonard, J. T., E-mail: jtleona01@gmail.com; Yonkee, B. P.; Cohen, D. A.; Megalini, L.; Speck, J. S. [Materials Department, University of California, Santa Barbara, California 93106 (United States); Lee, S. [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States); DenBaars, S. P.; Nakamura, S. [Materials Department, University of California, Santa Barbara, California 93106 (United States); Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States)

2016-01-18

We demonstrate a III-nitride nonpolar vertical-cavity surface-emitting laser (VCSEL) with a photoelectrochemically (PEC) etched aperture. The PEC lateral undercut etch is used to selectively remove the multi-quantum well (MQW) region outside the aperture area, defined by an opaque metal mask. This PEC aperture (PECA) creates an air-gap in the passive area of the device, allowing one to achieve efficient electrical confinement within the aperture, while simultaneously achieving a large index contrast between core of the device (the MQW within the aperture) and the lateral cladding of the device (the air-gap formed by the PEC etch), leading to strong lateral confinement. Scanning electron microscopy and focused ion-beam analysis is used to investigate the precision of the PEC etch technique in defining the aperture. The fabricated single mode PECA VCSEL shows a threshold current density of ∼22 kA/cm{sup 2} (25 mA), with a peak output power of ∼180 μW, at an emission wavelength of 417 nm. The near-field emission profile shows a clearly defined single linearly polarized (LP) mode profile (LP{sub 12,1}), which is in contrast to the filamentary lasing that is often observed in III-nitride VCSELs. 2D mode profile simulations, carried out using COMSOL, give insight into the different mode profiles that one would expect to be displayed in such a device. The experimentally observed single mode operation is proposed to be predominantly a result of poor current spreading in the device. This non-uniform current spreading results in a higher injected current at the periphery of the aperture, which favors LP modes with high intensities near the edge of the aperture.

Wind energy systems solutions for power quality and stabilization

CERN Document Server

Ali, Mohd Hasan

2012-01-01

Unlike conventional power plants, wind plants emit no air pollutants or greenhouse gases--and wind energy is a free, renewable resource. However, the induction machines commonly used as wind generators have stability problems similar to the transient stability of synchronous machines. To minimize power, frequency, and voltage fluctuations caused by network faults or random wind speed variations, control mechanisms are necessary. Wind Energy Systems: Solutions for Power Quality and Stabilization clearly explains how to solve stability and power quality issues of wind generator systems. Covering

Great expectations: large wind turbines

International Nuclear Information System (INIS)

De Vries, E.

2001-01-01

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

Dust-wind interactions can intensify aerosol pollution over eastern China.

Science.gov (United States)

Yang, Yang; Russell, Lynn M; Lou, Sijia; Liao, Hong; Guo, Jianping; Liu, Ying; Singh, Balwinder; Ghan, Steven J

2017-05-11

Eastern China has experienced severe and persistent winter haze episodes in recent years due to intensification of aerosol pollution. In addition to anthropogenic emissions, the winter aerosol pollution over eastern China is associated with unusual meteorological conditions, including weaker wind speeds. Here we show, based on model simulations, that during years with decreased wind speed, large decreases in dust emissions (29%) moderate the wintertime land-sea surface air temperature difference and further decrease winds by -0.06 (±0.05) m s -1 averaged over eastern China. The dust-induced lower winds enhance stagnation of air and account for about 13% of increasing aerosol concentrations over eastern China. Although recent increases in anthropogenic emissions are the main factor causing haze over eastern China, we conclude that natural emissions also exert a significant influence on the increases in wintertime aerosol concentrations, with important implications that need to be taken into account by air quality studies.

On the effect of wind direction and urban surroundings on natural ventilation of a large semi-enclosed stadium

NARCIS (Netherlands)

Hooff, van T.A.J.; Blocken, B.J.E.

2010-01-01

Natural ventilation of buildings refers to the replacement of indoor air with outdoor air due to pressure differences caused by wind and/or buoyancy. It is often expressed in terms of the air change rate per hour (ACH). The pressure differences created by the wind depend – among others – on the wind

Multi-scale wind erosion monitoring and assessment for US rangelands

Science.gov (United States)

Wind erosion is a major resource concern for rangeland managers. Although wind erosion is a naturally occurring process in many drylands, land use activities, and land management in particular, can accelerate wind-driven soil loss – impacting ecosystem dynamics and agricultural production, air quali...

Jet spoiler arrangement for wind turbine

Science.gov (United States)

Cyrus, J. D.; Kablec, E. G.; Klimas, P. C.

1983-09-01

An air jet spoiler arrangement is provided for a Darrieus-type vertical axis wind-powered turbine. Air is drawn into hollow turbine blades through air inlets at the end thereof and is ejected in the form of air jets through small holes or openings provided along the lengths of the blades. The air jets create flow separation at the surfaces of the turbine blades, thereby including stal conditions and reducing the output power. A feedback control unit senses the power output of the turbine and controls the amount of air drawn into the air inlets accordingly.

Jet spoiler arrangement for wind turbine

Science.gov (United States)

Cyrus, Jack D.; Kadlec, Emil G.; Klimas, Paul C.

1985-01-01

An air jet spoiler arrangement is provided for a Darrieus-type vertical axis wind-powered turbine. Air is drawn into hollow turbine blades through air inlets at the ends thereof and is ejected in the form of air jets through small holes or openings provided along the lengths of the blades. The air jets create flow separation at the surfaces of the turbine blades, thereby inducing stall conditions and reducing the output power. A feedback control unit senses the power output of the turbine and controls the amount of air drawn into the air inlets accordingly.

3D electromagnetic design and electrical characteristics analysis of a 10-MW-class hightemperature superconducting synchronous generator for wind power

International Nuclear Information System (INIS)

Kim, J. H.; Park, S. I.; Le, T. D.; Kim, H. M.

2014-01-01

In this paper, the general electromagnetic design process of a 10-MW-class high-temperature superconducting (HTS) synchronous generator that is intended to be utilized for large scale offshore wind generator is discussed. This paper presents three-dimensional (3D) electromagnetic design proposal and electrical characteristic analysis results of a 10-MW-class HTS synchronous generator for wind power. For more detailed design by reducing the errors of a two-dimensional (2D) design owing to leakage flux in air-gap, we redesign and analyze the 2D conceptual electromagnetic design model of the HTS synchronous generator using 3D finite element analysis (FEA) software. Then electrical characteristics which include the no-load and full-load voltage of generator, harmonic contents of these two load conditions, voltage regulation and losses of generator are analyzed by commercial 3D FEA software.

The relationship between the microwave radar cross section and both wind speed and stress: Model function studies using Frontal Air-Sea Interaction Experiment data

Science.gov (United States)

Weissman, David E.; Davidson, Kenneth L.; Brown, Robert A.; Friehe, Carl A.; Li, Fuk

1994-01-01

The Frontal Air-Sea Interaction Experiment (FASINEX) provided a unique data set with coincident airborne scatterometer measurements of the ocean surface radar cross section (RCS)(at Ku band) and near-surface wind and wind stress. These data have been analyzed to study new model functions which relate wind speed and surface friction velocity (square root of the kinematic wind stress) to the radar cross section and to better understand the processes in the boundary layer that have a strong influence on the radar backscatter. Studies of data from FASINEX indicate that the RCS has a different relation to the friction velocity than to the wind speed. The difference between the RCS models using these two variables depends on the polarization and the incidence angle. The radar data have been acquired from the Jet Propulsion Laboratory airborne scatterometer. These data span 10 different flight days. Stress measurements were inferred from shipboard instruments and from aircraft flying at low altitudes, closely following the scatterometer. Wide ranges of radar incidence angles and environmental conditions needed to fully develop algorithms are available from this experiment.

Flow Simulation of Modified Duct System Wind Turbines Installed on Vehicle

Science.gov (United States)

Rosly, N.; Mohd, S.; Zulkafli, M. F.; Ghafir, M. F. Abdul; Shamsudin, S. S.; Muhammad, W. N. A. Wan

2017-10-01

This study investigates the characteristics of airflow with a flow guide installed and output power generated by wind turbine system being installed on a pickup truck. The wind turbine models were modelled by using SolidWorks 2015 software. In order to investigate the characteristic of air flow inside the wind turbine system, a computer simulation (by using ANSYS Fluent software) is used. There were few models being designed and simulated, one without the rotor installed and another two with rotor installed in the wind turbine system. Three velocities being used for the simulation which are 16.7 m/s (60 km/h), 25 m/s (90 km/h) and 33.33 m/s (120 km/h). The study proved that the flow guide did give an impact to the output power produced by the wind turbine system. The predicted result from this study is the velocity of the air inside the ducting system of the present model is better that reference model. Besides, the flow guide implemented in the ducting system gives a big impact on the characteristics of the air flow.

Technical analysis of utilization suitability of various wind rotor’s types for compressor’s power driving

Directory of Open Access Journals (Sweden)

Radim Rybár

2005-03-01

Full Text Available Conception is from the converting of wind energy, which flows across the wind turbine in mechanic work needed for compressor working. The wind motor one part of energy transform into mechanical work, part of energy is unused and part of energy of stead flow is transformed into eddy after wind rotor.The aim was rendering of technical analysis for equipment, which would use the wind with parameters for chosen area and whole unit would supply power in peak demand. Unit consists of wind turbine, which pushes compressor. Compressor pumps air into the compressed air storage. The air is used for power producing in time of peak demand.

Thermodynamic assessment of a wind turbine based combined cycle

International Nuclear Information System (INIS)

Rabbani, M.; Dincer, I.; Naterer, G.F.

2012-01-01

Combined cycles use the exhaust gases released from a Gas Turbine (GT). Approximately 30–40% of the turbine shaft work is typically used to drive the Compressor. The present study analyzes a system that couples a Wind Turbine (WT) with a combined cycle. It demonstrates how a WT can be used to supply power to the Compressor in the GT cycle and pump fluid through a reheat Rankine cycle, in order to increase the overall power output. Three different configurations are discussed, namely high penetration, low penetration and wind power addition. In the case of a low electricity demand and high penetration configuration, extra wind power is used to compress air which can then be used in the low penetration configuration. During a high load demand, all the wind power is used to drive the pump and compressor and if required additional compressed air is supplied by a storage unit. The analysis shows that increasing the combustion temperature reduces the critical velocity and mass flow rate. Increases in wind speed reduce both energy and exergy efficiency of the overall system. -- Highlights: ► This study analyzes a system that couples a wind turbine with a combined power generation cycle. ► Surplus wind power is used to compress air, which is then stored and used at a later time. ► Increasing the pressure ratio will reduce the work ratio between the Rankine and Brayton cycles. ► A higher combustion temperature will increase the net work output, as well as the system energy and exergy efficiencies.

Verification and implementation of microburst day potential index (MDPI) and wind INDEX (WINDEX) forecasting tools at Cape Canaveral Air Station

Science.gov (United States)

Wheeler, Mark

1996-01-01

This report details the research, development, utility, verification and transition on wet microburst forecasting and detection the Applied Meteorology Unit (AMU) did in support of ground and launch operations at Kennedy Space Center (KSC) and Cape Canaveral Air Station (CCAS). The unforecasted wind event on 16 August 1994 of 33.5 ms-1 (65 knots) at the Shuttle Landing Facility raised the issue of wet microburst detection and forecasting. The AMU researched and analyzed the downburst wind event and determined it was a wet microburst event. A program was developed for operational use on the Meteorological Interactive Data Display System (MIDDS) weather system to analyze, compute and display Theta(epsilon) profiles, the microburst day potential index (MDPI), and wind index (WINDEX) maximum wind gust value. Key microburst nowcasting signatures using the WSR-88D data were highlighted. Verification of the data sets indicated that the MDPI has good potential in alerting the duty forecaster to the potential of wet microburst and the WINDEX values computed from the hourly surface data do have potential in showing a trend for the maximum gust potential. WINDEX should help in filling in the temporal hole between the MDPI on the last Cape Canaveral rawinsonde and the nowcasting radar data tools.

Solar wind structure out of the ecliptic plane over solar cycles

Science.gov (United States)

Sokol, J. M.; Bzowski, M.; Tokumaru, M.

2017-12-01

Sun constantly emits a stream of plasma known as solar wind. Ground-based observations of the solar wind speed through the interplanetary scintillations (IPS) of radio flux from distant point sources and in-situ measurements by Ulysses mission revealed that the solar wind flow has different characteristics depending on the latitude. This latitudinal structure evolves with the cycle of solar activity. The knowledge on the evolution of solar wind structure is important for understanding the interaction between the interstellar medium surrounding the Sun and the solar wind, which is responsible for creation of the heliosphere. The solar wind structure must be taken into account in interpretation of most of the observations of heliospheric energetic neutral atoms, interstellar neutral atoms, pickup ions, and heliospheric backscatter glow. The information on the solar wind structure is not any longer available from direct measurements after the termination of Ulysses mission and the only source of the solar wind out of the ecliptic plane is the IPS observations. However, the solar wind structure obtained from this method contains inevitable gaps in the time- and heliolatitude coverage. Sokół et al 2015 used the solar wind speed data out of the ecliptic plane retrieved from the IPS observations performed by Institute for Space-Earth Environmental Research (Nagoya University, Japan) and developed a methodology to construct a model of evolution of solar wind speed and density from 1985 to 2013 that fills the data gaps. In this paper we will present a refined model of the solar wind speed and density structure as a function of heliographic latitude updated by the most recent data from IPS observations. And we will discuss methods of extrapolation of the solar wind structure out of the ecliptic plane for the past solar cycles, when the data were not available, as well as forecasting for few years upward.

Transmission Congestion Management using a Wind Integrated Compressed Air Energy Storage System

Directory of Open Access Journals (Sweden)

S. Gope

2017-08-01

Full Text Available Transmission congestion is a vital problem in the power system security and reliability sector. To ensure the stable operation of the system, a congestion free power network is desirable. In this paper, a new Congestion Management (CM technique, the Wind integrated Compressed Air Energy Storage (WCAES system is used to alleviate transmission congestion and to minimize congestion mitigation cost. The CM problem has been solved by using the Generator Sensitivity Factor (GSF and the Bus Sensitivity Factor (BSF. BSF is used for finding the optimal location of WCAES in the system. GSF with a Moth Flame Optimization (MFO algorithm is used for rescheduling the generators to alleviate congestion and to minimize congestion cost by improving security margin. The impact of the WCAES system is tested with a 39 bus system. To validate this approach, the same problem has been solved with a Particle Swarm Optimization (PSO algorithm and the obtained results are compared with the ones from the MFO algorithm.

Influence of orographically steered winds on Mutsu Bay surface currents

Science.gov (United States)

Yamaguchi, Satoshi; Kawamura, Hiroshi

2005-09-01

Effects of spatially dependent sea surface wind field on currents in Mutsu Bay, which is located at the northern end of Japanese Honshu Island, are investigated using winds derived from synthetic aperture radar (SAR) images and a numerical model. A characteristic wind pattern over the bay was evidenced from analysis of 118 SAR images and coincided with in situ observations. Wind is topographically steered with easterly winds entering the bay through the terrestrial gap and stronger wind blowing over the central water toward its mouth. Nearshore winds are weaker due to terrestrial blockages. Using the Princeton Ocean Model, we investigated currents forced by the observed spatially dependent wind field. The predicted current pattern agrees well with available observations. For a uniform wind field of equal magnitude and average direction, the circulation pattern departs from observations demonstrating that vorticity input due to spatially dependent wind stress is essential in generation of the wind-driven current in Mutsu Bay.

Permanent magnet motor drives with switched stator windings

Energy Technology Data Exchange (ETDEWEB)

Nipp, E.

1999-06-01

Permanent magnet (PM) motors are today regarded as an interesting solution for a wide range of inverter-fed variable-speed drives. The generally increased interest in these motors has led to many investigations on their feasibility for vehicle propulsion. Consequently, they are also of interest for traction applications which led to the research project that is presented in this thesis. The most important advantages that are expected in comparison to the state of the art asynchronous motors are lower losses and a higher torque density. Often the field weakening speed range is important, but difficult to obtain with PM machines because the inductance in the direction of the magnetization tends to be low. An alternative can be to switch different coils groups of the stator winding into different configurations. This is the central topic of this thesis. Various aspects of the design of PM motor drives are considered with special attention to the requirements for the application of the switched winding concept. The studies were thereby limited to the inner rotor, radial flux topology. It was found that two winding parts per phase, implying four different winding connections, is the only interesting solution. An advantage of switched windings is that the internal voltage of the machine will never exceed the maximum inverter output, which increases the operation safety. Furthermore the machine design can uncompromisingly be optimized for operation below base speed, which means low inductances implying a large air gap length and thick magnets. A problem with switched windings is that circulating currents can occur. To diminish them, a 2/3 magnet covering of the pole surface must be chosen in combination with a non-salient rotor. Moreover it was found that the eddy current losses in the magnets can reach non-negligible levels and must be considered when designing a drive system. The major drawback of switched stator windings is probably the occurrence of torque

Wind turbine aerodynamics

Energy Technology Data Exchange (ETDEWEB)

Johnson, D.A. [Waterloo Univ., ON (Canada). Dept. of Mechanical Engineering, Wind Energy Group

2010-07-01

The need for clean, renewable electricity in remote communities of Canada and the world was discussed in this presentation. The University of Waterloo Wind Energy Laboratory (WEL) performs research in a large scale indoor environment on wind turbines, blade aerodynamics, and aeroacoustics. A key area of research involves developing turbines for remote off-grid communities where climatic conditions are challenging. This presentation outlined research that is underway on wind energy and off-grid renewable energy systems. Many communities in Canada and remote communities in the rest of the world are not connected to the grid and are dependent on other means to supply electrical energy to their community. Remote communities in northern Canada have no road access and diesel is the dominant source of electrical energy for these communities. All of the community supply of diesel comes from brief winter road access or by air. The presentation discussed existing diesel systems and the solution of developing local renewable energy sources such as wind, hydro, biomass, geothermal, and solar power. Research goals, wind energy activities, experimental equipment, and the results were also presented. Research projects have been developed in wind energy; hydrogen generation/storage/utilization; power electronics/microgrid; and community engagement. figs.

Air flow distribution in and around a single-sided naturally ventilated room

Energy Technology Data Exchange (ETDEWEB)

Eftekhari, M.M.; Marjanovic, L.D.; Pinnock, D.J. [Loughborough University (United Kingdom). Dept. of Civil and Building Engineering

2002-03-01

The objective of this research is to compare calculated and measured air flow distributions inside a test room which is naturally ventilated. The test room is situated in a relatively sheltered location and to visualise the resultant local wind pattern around the room for all prevailing wind directions, wind tunnel trials were carried out. Both the wind tunnel and full-scale measurements show that the wind direction at the test cell was generally restricted to either a westerly or an easterly direction. To investigate air flow inside the room, the air pressures and velocities across the openings together with indoor air temperature and velocity at four locations and six different levels are measured. The experimental results demonstrate that for both winter and summer the air was entering the test room at bottom and leaving at the top louvre. Separate air flow and thermal modelling programs are used to predict the spatial distribution of the air flow and thermal comfort. The air flow distribution was predicted using a network air flow program. The predicted flow showed similar trends and the simulation results were in agreement with the measured data. An explicit finite-difference thermal modeling simulation package was used to predict the thermal comfort indices.(author)

Gap deformation and classical wave localization in disordered two-dimensional photonic-band-gap materials

International Nuclear Information System (INIS)

Lidorikis, E.; Sigalas, M. M.; Economou, E. N.; Soukoulis, C. M.

2000-01-01

By using two ab initio numerical methods, we study the effects that disorder has on the spectral gaps and on wave localization in two-dimensional photonic-band-gap materials. We find that there are basically two different responses depending on the lattice realization (solid dielectric cylinders in air or vice versa), the wave polarization, and the particular form under which disorder is introduced. Two different pictures for the photonic states are employed, the ''nearly free'' photon and the ''strongly localized'' photon. These originate from the two different mechanisms responsible for the formation of the spectral gaps, i.e., multiple scattering and single scatterer resonances, and they qualitatively explain our results. (c) 2000 The American Physical Society

Large-scale analysis and forecast experiments with wind data from the Seasat A scatterometer

Science.gov (United States)

Baker, W. E.; Atlas, R.; Kalnay, E.; Halem, M.; Woiceshyn, P. M.; Peteherych, S.; Edelmann, D.

1984-01-01

A series of data assimilation experiments is performed to assess the impact of Seasat A satellite scatterometer (SASS) wind data on Goddard Laboratory for Atmospheric Sciences (GLAS) model forecasts. The SASS data are dealiased as part of an objective analysis system utilizing a three-pass procedure. The impact of the SASS data is evaluated with and without temperature soundings from the NOAA 4 Vertical Temperature Profile Radiometer (VTPR) instrument in order to study possible redundancy between surface wind data and upper air temperature data. In the northern hemisphere the SASS data are generally found to have a negligible effect on the forecasts. In the southern hemisphere the forecast impact from SASS data is somewhat larger and primarily beneficial in the absence of VTPR data. However, the inclusion of VTPR data effectively eliminates the positive impact over Australia and South America. This indicates that SASS data can be beneficial for numerical weather prediction in regions with large data gaps, but in the presence of satellite soundings the usefulness of SASS data is significantly reduced.

Conflict Resolution for Wind-Optimal Aircraft Trajectories in North Atlantic Oceanic Airspace with Wind Uncertainties

Science.gov (United States)

Rodionova, Olga; Sridhar, Banavar; Ng, Hok K.

2016-01-01

Air traffic in the North Atlantic oceanic airspace (NAT) experiences very strong winds caused by jet streams. Flying wind-optimal trajectories increases individual flight efficiency, which is advantageous when operating in the NAT. However, as the NAT is highly congested during peak hours, a large number of potential conflicts between flights are detected for the sets of wind-optimal trajectories. Conflict resolution performed at the strategic level of flight planning can significantly reduce the airspace congestion. However, being completed far in advance, strategic planning can only use predicted environmental conditions that may significantly differ from the real conditions experienced further by aircraft. The forecast uncertainties result in uncertainties in conflict prediction, and thus, conflict resolution becomes less efficient. This work considers wind uncertainties in order to improve the robustness of conflict resolution in the NAT. First, the influence of wind uncertainties on conflict prediction is investigated. Then, conflict resolution methods accounting for wind uncertainties are proposed.

Wind profile radar for study of Antarctic air circulation

International Nuclear Information System (INIS)

Ragaini, E.; Sarango, M.F.; Vasquez, E.H.

1992-01-01

After a brief discussion of meteorological methods used in the Antarctic, the paper gives an outline of a coordinated international research project whose objective is to set up a wind profiler radar station that would give meteorologists information regarding Antarctic atmospheric dynamics useful in their investigation of the causes and effects of the hole in the ozone layer. The radar instrumentation is to provide continuous readings of wind velocity at varying altitudes above the polar continent

Assessment of research needs for wind turbine rotor materials technology

Energy Technology Data Exchange (ETDEWEB)

1991-01-01

Wind-driven power systems is a renewable energy technology that is still in the early stages of development. Wind power plants installed in early 1980s suffered structural failures chiefly because of incomplete understanding of wind forces (turbulent), in some cases because of poor product quality. Failures of rotor blades are now somewhat better understood. This committee has examined the experience base accumulated by wind turbines and the R and D programs sponsored by DOE. It is concluded that a wind energy system such as is described is within the capability of engineering practice; however because of certain gaps in knowledge, and the presence of only one major integrated manufacturer of wind power machines in the USA, a DOE R and D investment is still required.

Spatiotemporal distribution of nitrogen dioxide within and around a large-scale wind farm – a numerical case study

Directory of Open Access Journals (Sweden)

J. Mo

2017-12-01

Full Text Available As a renewable and clean energy source, wind power has become the most rapidly growing energy resource worldwide in the past decades. Wind power has been thought not to exert any negative impacts on the environment. However, since a wind farm can alter the local meteorological conditions and increase the surface roughness lengths, it may affect air pollutants passing through and over the wind farm after released from their sources and delivered to the wind farm. In the present study, we simulated the nitrogen dioxide (NO2 air concentration within and around the world's largest wind farm (Jiuquan wind farm in Gansu Province, China using a coupled meteorology and atmospheric chemistry model WRF-Chem. The results revealed an edge effect, which featured higher NO2 levels at the immediate upwind and border region of the wind farm and lower NO2 concentration within the wind farm and the immediate downwind transition area of the wind farm. A surface roughness length scheme and a wind turbine drag force scheme were employed to parameterize the wind farm in this model investigation. Modeling results show that both parameterization schemes yield higher concentration in the immediate upstream of the wind farm and lower concentration within the wind farm compared to the case without the wind farm. We infer this edge effect and the spatial distribution of air pollutants to be the result of the internal boundary layer induced by the changes in wind speed and turbulence intensity driven by the rotation of the wind turbine rotor blades and the enhancement of surface roughness length over the wind farm. The step change in the roughness length from the smooth to rough surfaces (overshooting in the upstream of the wind farm decelerates the atmospheric transport of air pollutants, leading to their accumulation. The rough to the smooth surface (undershooting in the downstream of the wind farm accelerates the atmospheric transport of air pollutants, resulting in

Analysis and Design Considerations of a High-Power Density, Dual Air Gap, Axial-Field Brushless, Permanent Magnet Motor.

Science.gov (United States)

Cho, Chahee Peter

1995-01-01

Until recently, brush dc motors have been the dominant drive system because they provide easily controlled motor speed over a wide range, rapid acceleration and deceleration, convenient control of position, and lower product cost. Despite these capabilities, the brush dc motor configuration does not satisfy the design requirements for the U.S. Navy's underwater propulsion applications. Technical advances in rare-earth permanent magnet materials, in high-power semiconductor transistor technology, and in various rotor position-sensing devices have made using brushless permanent magnet motors a viable alternative. This research investigates brushless permanent magnet motor technology, studying the merits of dual-air gap, axial -field, brushless, permanent magnet motor configuration in terms of power density, efficiency, and noise/vibration levels. Because the design objectives for underwater motor applications include high-power density, high-performance, and low-noise/vibration, the traditional, simplified equivalent circuit analysis methods to assist in meeting these goals were inadequate. This study presents the development and verification of detailed finite element analysis (FEA) models and lumped parameter circuit models that can calculate back electromotive force waveforms, inductance, cogging torque, energized torque, and eddy current power losses. It is the first thorough quantification of dual air-gap, axial -field, brushless, permanent magnet motor parameters and performance characteristics. The new methodology introduced in this research not only facilitates the design process of an axial field, brushless, permanent magnet motor but reinforces the idea that the high-power density, high-efficiency, and low-noise/vibration motor is attainable.

Design and optimization of resistance wire electric heater for hypersonic wind tunnel

Science.gov (United States)

Rehman, Khurram; Malik, Afzaal M.; Khan, I. J.; Hassan, Jehangir

2012-06-01

The range of flow velocities of high speed wind tunnels varies from Mach 1.0 to hypersonic order. In order to achieve such high speed flows, a high expansion nozzle is employed in the converging-diverging section of wind tunnel nozzle. The air for flow is compressed and stored in pressure vessels at temperatures close to ambient conditions. The stored air is dried and has minimum amount of moisture level. However, when this air is expanded rapidly, its temperature drops significantly and liquefaction conditions can be encountered. Air at near room temperature will liquefy due to expansion cooling at a flow velocity of more than Mach 4.0 in a wind tunnel test section. Such liquefaction may not only be hazardous to the model under test and wind tunnel structure; it may also affect the test results. In order to avoid liquefaction of air, a pre-heater is employed in between the pressure vessel and the converging-diverging section of a wind tunnel. A number of techniques are being used for heating the flow in high speed wind tunnels. Some of these include the electric arc heating, pebble bed electric heating, pebble bed natural gas fired heater, hydrogen burner heater, and the laser heater mechanisms. The most common are the pebble bed storage type heaters, which are inefficient, contaminating and time consuming. A well designed electrically heating system can be efficient, clean and simple in operation, for accelerating the wind tunnel flow up to Mach 10. This paper presents CFD analysis of electric preheater for different configurations to optimize its design. This analysis has been done using ANSYS 12.1 FLUENT package while geometry and meshing was done in GAMBIT.

Optical Selection Rule of Excitons in Gapped Chiral Fermion Systems

Science.gov (United States)

Zhang, Xiaoou; Shan, Wen-Yu; Xiao, Di

2018-02-01

We show that the exciton optical selection rule in gapped chiral fermion systems is governed by their winding number w , a topological quantity of the Bloch bands. Specifically, in a CN-invariant chiral fermion system, the angular momentum of bright exciton states is given by w ±1 +n N with n being an integer. We demonstrate our theory by proposing two chiral fermion systems capable of hosting dark s -like excitons: gapped surface states of a topological crystalline insulator with C4 rotational symmetry and biased 3 R -stacked MoS2 bilayers. In the latter case, we show that gating can be used to tune the s -like excitons from bright to dark by changing the winding number. Our theory thus provides a pathway to electrical control of optical transitions in two-dimensional material.

Radar-cross-section reduction of wind turbines. part 1.

Energy Technology Data Exchange (ETDEWEB)

Brock, Billy C.; Loui, Hung; McDonald, Jacob J.; Paquette, Joshua A.; Calkins, David A.; Miller, William K.; Allen, Steven E.; Clem, Paul Gilbert; Patitz, Ward E.

2012-03-05

In recent years, increasing deployment of large wind-turbine farms has become an issue of growing concern for the radar community. The large radar cross section (RCS) presented by wind turbines interferes with radar operation, and the Doppler shift caused by blade rotation causes problems identifying and tracking moving targets. Each new wind-turbine farm installation must be carefully evaluated for potential disruption of radar operation for air defense, air traffic control, weather sensing, and other applications. Several approaches currently exist to minimize conflict between wind-turbine farms and radar installations, including procedural adjustments, radar upgrades, and proper choice of low-impact wind-farm sites, but each has problems with limited effectiveness or prohibitive cost. An alternative approach, heretofore not technically feasible, is to reduce the RCS of wind turbines to the extent that they can be installed near existing radar installations. This report summarizes efforts to reduce wind-turbine RCS, with a particular emphasis on the blades. The report begins with a survey of the wind-turbine RCS-reduction literature to establish a baseline for comparison. The following topics are then addressed: electromagnetic model development and validation, novel material development, integration into wind-turbine fabrication processes, integrated-absorber design, and wind-turbine RCS modeling. Related topics of interest, including alternative mitigation techniques (procedural, at-the-radar, etc.), an introduction to RCS and electromagnetic scattering, and RCS-reduction modeling techniques, can be found in a previous report.

Three-dimensional vapor intrusion modeling approach that combines wind and stack effects on indoor, atmospheric, and subsurface domains.

Science.gov (United States)

Shirazi, Elham; Pennell, Kelly G

2017-12-13

Vapor intrusion (IV) exposure risks are difficult to characterize due to the role of atmospheric, building and subsurface processes. This study presents a three-dimensional VI model that extends the common subsurface fate and transport equations to incorporate wind and stack effects on indoor air pressure, building air exchange rate (AER) and indoor contaminant concentration to improve VI exposure risk estimates. The model incorporates three modeling programs: (1) COMSOL Multiphysics to model subsurface fate and transport processes, (2) CFD0 to model atmospheric air flow around the building, and (3) CONTAM to model indoor air quality. The combined VI model predicts AER values, zonal indoor air pressures and zonal indoor air contaminant concentrations as a function of wind speed, wind direction and outdoor and indoor temperature. Steady state modeling results for a single-story building with a basement demonstrate that wind speed, wind direction and opening locations in a building play important roles in changing the AER, indoor air pressure, and indoor air contaminant concentration. Calculated indoor air pressures ranged from approximately -10 Pa to +4 Pa depending on weather conditions and building characteristics. AER values, mass entry rates and indoor air concentrations vary depending on weather conditions and building characteristics. The presented modeling approach can be used to investigate the relationship between building features, AER, building pressures, soil gas concentrations, indoor air concentrations and VI exposure risks.

Tool for Forecasting Cool-Season Peak Winds Across Kennedy Space Center and Cape Canaveral Air Force Station

Science.gov (United States)

Barrett, Joe H., III; Roeder, William P.

2010-01-01

The expected peak wind speed for the day is an important element in the daily morning forecast for ground and space launch operations at Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS). The 45th Weather Squadron (45 WS) must issue forecast advisories for KSC/CCAFS when they expect peak gusts for >= 25, >= 35, and >= 50 kt thresholds at any level from the surface to 300 ft. In Phase I of this task, the 45 WS tasked the Applied Meteorology Unit (AMU) to develop a cool-season (October - April) tool to help forecast the non-convective peak wind from the surface to 300 ft at KSC/CCAFS. During the warm season, these wind speeds are rarely exceeded except during convective winds or under the influence of tropical cyclones, for which other techniques are already in use. The tool used single and multiple linear regression equations to predict the peak wind from the morning sounding. The forecaster manually entered several observed sounding parameters into a Microsoft Excel graphical user interface (GUI), and then the tool displayed the forecast peak wind speed, average wind speed at the time of the peak wind, the timing of the peak wind and the probability the peak wind will meet or exceed 35, 50 and 60 kt. The 45 WS customers later dropped the requirement for >= 60 kt wind warnings. During Phase II of this task, the AMU expanded the period of record (POR) by six years to increase the number of observations used to create the forecast equations. A large number of possible predictors were evaluated from archived soundings, including inversion depth and strength, low-level wind shear, mixing height, temperature lapse rate and winds from the surface to 3000 ft. Each day in the POR was stratified in a number of ways, such as by low-level wind direction, synoptic weather pattern, precipitation and Bulk Richardson number. The most accurate Phase II equations were then selected for an independent verification. The Phase I and II forecast methods were

Tonopah Test Range Air Monitoring: CY2016 Meteorological, Radiological, and Wind Transported Particulate Observations

Energy Technology Data Exchange (ETDEWEB)

Chapman, Jenny [Desert Research Inst. (DRI), Las Vegas, NV (United States); Nikolich, George [Desert Research Inst. (DRI), Las Vegas, NV (United States); Shadel, Craig [Desert Research Inst. (DRI), Las Vegas, NV (United States); McCurdy, Greg [Desert Research Inst. (DRI), Las Vegas, NV (United States); Etyemezian, Vicken [Desert Research Inst. (DRI), Las Vegas, NV (United States); Miller, Julianne J [Desert Research Inst. (DRI), Las Vegas, NV (United States); Mizell, Steve [Desert Research Inst. (DRI), Las Vegas, NV (United States)

2017-10-01

In 1963, the U.S. Department of Energy (DOE) (formerly the Atomic Energy Commission [AEC]), implemented Operation Roller Coaster on the Tonopah Test Range (TTR) and an adjacent area of the Nevada Test and Training Range (NTTR) (formerly the Nellis Air Force Range). This operation resulted in radionuclide-contaminated soils at the Clean Slate I, II, and III sites. This report documents observations made during ongoing monitoring of radiological, meteorological, and dust conditions at stations installed adjacent to Clean Slate I and Clean Slate III, and at the TTR Sandia National Laboratories (SNL) Range Operations Control (ROC) center. The primary objective of the monitoring effort is to determine if wind blowing across the Clean Slate sites is transporting particles of radionuclide-contaminated soil beyond the physical and administrative boundaries of the sites.

Net sea–air CO2 flux uncertainties in the Bay of Biscay based on the choice of wind speed products and gas transfer parameterizations

Directory of Open Access Journals (Sweden)

P. Otero

2013-05-01

Full Text Available The estimation of sea–air CO2 fluxes is largely dependent on wind speed through the gas transfer velocity parameterization. In this paper, we quantify uncertainties in the estimation of the CO2 uptake in the Bay of Biscay resulting from the use of different sources of wind speed such as three different global reanalysis meteorological models (NCEP/NCAR 1, NCEP/DOE 2 and ERA-Interim, one high-resolution regional forecast model (HIRLAM-AEMet, winds derived under the Cross-Calibrated Multi-Platform (CCMP project, and QuikSCAT winds in combination with some of the most widely used gas transfer velocity parameterizations. Results show that net CO2 flux estimations during an entire seasonal cycle (September 2002–September 2003 may vary by a factor of ~ 3 depending on the selected wind speed product and the gas exchange parameterization, with the highest impact due to the last one. The comparison of satellite- and model-derived winds with observations at buoys advises against the systematic overestimation of NCEP-2 and the underestimation of NCEP-1. In the coastal region, the presence of land and the time resolution are the main constraints of QuikSCAT, which turns CCMP and ERA-Interim in the preferred options.

Power Performance Test Report for the SWIFT Wind Turbine

Energy Technology Data Exchange (ETDEWEB)

Mendoza, I.; Hur, J.

2012-12-01

This report summarizes the results of a power performance test that NREL conducted on the SWIFT wind turbine. This test was conducted in accordance with the International Electrotechnical Commission's (IEC) standard, Wind Turbine Generator Systems Part 12: Power Performance Measurements of Electricity Producing Wind Turbines, IEC 61400-12-1 Ed.1.0, 2005-12. However, because the SWIFT is a small turbine as defined by IEC, NREL also followed Annex H that applies to small wind turbines. In these summary results, wind speed is normalized to sea-level air density.

Investigating Solutions to Wind Washing Issues in Two-Story Florida Homes, Phase 2

Energy Technology Data Exchange (ETDEWEB)

Withers, C. [Building America Partnership for Improved Residential Construction, Cocoa, FL (United States); Kono, J. [Building America Partnership for Improved Residential Construction, Cocoa, FL (United States)

2015-04-01

This report provides results from a second-phase research study of a phenomenon generally referred to as wind washing. Wind washing is the movement of unconditioned air around or through building thermal barriers in such a way as to diminish or nullify the intended thermal performance. In some cases, thermal and air barriers are installed very poorly or not at all, and air can readily move from unconditioned attic spaces into quasi-conditioned interstitial spaces. This study focused on the impact of poorly sealed and insulated floor cavities adjacent to attic spaces in Florida homes. In these cases, unconditioned attic air can be transferred into floor cavities through pathways driven by natural factors such as wind, or by thermal differences between the floor cavity and the attic. Air can also be driven into a floor cavity through mechanical forces imposed by return duct leakage in the floor cavity.

Improving Energy Security for Air Force Installations

Science.gov (United States)

2015-09-01

equipment, and habitat destruction from general construction (DoE, “ Wind Turbine Interactions with Birds , Bats, and Their Habitats,” pgs 2-4). Another...utility-resource-efficiency>, accessed 16 December 2014. Department of Energy, Wind Turbine Interactions with Birds , Bats, and Their Habitats... Wind power is a mature technology, with wind turbines first being used for electricity in the late 19th century. The Air Force operates two wind

Wind Farm Wake: The Horns Rev Photo Case

Directory of Open Access Journals (Sweden)

Pierre-Elouan Réthoré

2013-02-01

Full Text Available The aim of the paper is to examine the nowadays well-known wind farm wake photographs taken on 12 February 2008 at the offshore Horns Rev 1 wind farm. The meteorological conditions are described from observations from several satellite sensors quantifying clouds, surface wind vectors and sea surface temperature as well as ground-based information at and near the wind farm, including Supervisory Control and Data Acquisition (SCADA data. The SCADA data reveal that the case of fog formation occurred 12 February 2008 on the 10:10 UTC. The fog formation is due to very special atmospheric conditions where a layer of cold humid air above a warmer sea surface re-condensates to fog in the wake of the turbines. The process is fed by warm humid air up-drafted from below in the counter-rotating swirl generated by the clock-wise rotating rotors. The condensation appears to take place primarily in the wake regions with relatively high axial velocities and high turbulent kinetic energy. The wind speed is near cut-in and most turbines produce very little power. The rotational pattern of spiraling bands produces the large-scale structure of the wake fog.

Design and analysis of a semi-submersible vertical axis wind turbine

OpenAIRE

Siddique, Muhammad Abu Zafar

2017-01-01

Wind energy are deployed by two types of wind turbines. They are Horizontal Axis Wind Turbine (HAWT) and Vertical Axis Wind Turbine (VAWT), classified according to their axis of rotation. In recent years, offshore wind energy playing a vital role in the wind turbine industry due to high intensity of air, less turbulent and comparatively clean and easily employed in large area which is difficult to manage for onshore or near-shore. The advantages of HAWTs are now facing different challenge in ...

Linear wind generator

International Nuclear Information System (INIS)

Kozarov, A.; Petrov, O.; Antonov, J.; Sotirova, S.; Petrova, B.

2006-01-01

The purpose of the linear wind-power generator described in this article is to decrease the following disadvantages of the common wind-powered turbine: 1) large bending and twisting moments to the blades and the shaft, especially when strong winds and turbulence exist; 2) significant values of the natural oscillation period of the construction result in the possibility of occurrence of destroying resonance oscillations; 3) high velocity of the peripheral parts of the rotor creating a danger for birds; 4) difficulties, connected with the installation and the operation on the mountain ridges and passages where the wind energy potential is the largest. The working surfaces of the generator in questions driven by the wind are not connected with a joint shaft but each moves along a railway track with few oscillations. So the sizes of each component are small and their number can be rather large. The mechanical trajectory is not a circle but a closed outline in a vertical plain, which consists of two rectilinear sectors, one above the other, connected in their ends by semi-circumferences. The mechanical energy of each component turns into electrical on the principle of the linear electrical generator. A regulation is provided when the direction of the wind is perpendicular to the route. A possibility of effectiveness is shown through aiming of additional quantities of air to the movable components by static barriers

Calculation and design of steel bearing structure for wind turbine

Directory of Open Access Journals (Sweden)

Bešević Miroslav

2014-01-01

Full Text Available Wind represents directed movement of the air and is caused by differences in atmospheric pressure which are caused by uneven heating of air masses. Global and local winds can be distinguished. Global winds have high altitude, while local winds occur in the ground layer of the atmosphere. Given that the global wings have high altitude they cannot be used as propellant for wind generators, but they should be known for their effects on the winds in the lower atmosphere. Modern wind turbines are made with a horizontal axle that has a system for the swiveling axis in the horizontal plane for tracking wind direction changes. They can have different number of blades, but for larger forces three blades are commonly used because they provide the greatest efficiency. Rotor diameter of these turbines depends on the strength and it ranges from 30 m for the power of 300 kW to 115 m for the power of 5 MW. Wind turbines are mounted on vertical steel tower which can be high even more than 100 m. Depending on the diameter of the turbine rotor, column is usually built as steel conical and less often as a steel-frame. This study includes analysis and design of steel tower for wind generator made by manufacturer Vestas, type V112 3MW HH 119 (power 3.2 MW for the construction of wind farm 'Kovačica'.

Assessment of Climate Air Energy Regional Schemes in Burgundy and in Franche-Comte - Intermediate review on June 27, 2017. Burgundy Climate Air Energy Regional Scheme. Project, Scheme, Appendix to the SRCAE - Wind regional scheme of Burgundy, synthesis, opinion of the Burgundy CESER. Territorial Climate Energy Plan - Program of actions, Plenary session of the November 25, 2013. Climate Air Energy Regional Scheme - Franche-Comte SRCAE

International Nuclear Information System (INIS)

2011-09-01

A first report proposes an assessment of the various aspects addressed by the Climate Air Energy Regional Schemes (SRCAE) of Burgundy and Franche-Comte: global aspects, and aspects related to adaptation to climate change, to air quality, to land planning, to the building sector, to mobility, to good transports, to agriculture, to forest, to industry and craft, to renewable energies, and to ecological responsibility. A synthetic presentation of the Burgundy scheme is proposed, and then an extended version which contains a description of the situation, an analysis of the regional potential, and a definition of orientations for the same above-mentioned aspects. A document more particularly addresses wind energy: role of wind energy in the energy mix of the region, role of small installations, wind energy potential, challenges and constraints (heritage and landscapes, natural environment, technical constraints), identification of areas of interest for wind energy projects, qualitative objectives. Documents published by the regional economic, social and environmental Council (CESER) of Burgundy are then proposed: a contribution to the Climate Air Energy Regional Scheme, a discussion and a presentation of a program of actions for the Climate Energy Territorial Plan (a large number of sheets of presentation of actions is proposed). The last document presents the Franche-Comte regional scheme: overview of regional knowledge on climate, air quality and environmental issues, challenges and potential per activity sector (transports and development, building, agriculture, industry, renewable energy production), definition of orientations and objectives for axes of action

A solar PV augmented hybrid scheme for enhanced wind power generation through improved control strategy for grid connected doubly fed induction generator

Directory of Open Access Journals (Sweden)

Adikanda Parida

2016-12-01

Full Text Available In this paper, a wind power generation scheme using a grid connected doubly fed induction generator (DFIG augmented with solar PV has been proposed. A reactive power-based rotor speed and position estimation technique with reduced machine parameter sensitivity is also proposed to improve the performance of the DFIG controller. The estimation algorithm is based on model reference adaptive system (MRAS, which uses the air gap reactive power as the adjustable variable. The overall generation reliability of the wind energy conversion system can be considerably improved as both solar and wind energy can supplement each other during lean periods of either of the sources. The rotor-side DC-link voltage and active power generation at the stator terminals of the DFIG are maintained constant with minimum storage battery capacity using single converter arrangement without grid-side converter (GSC. The proposed scheme has been simulated and experimentally validated with a practical 2.5 kW DFIG using dSPACE CP1104 module which produced satisfactory results.

The potential impacts of climate variability and change on air pollution-related health effects in the United States.

Science.gov (United States)

Bernard, S M; Samet, J M; Grambsch, A; Ebi, K L; Romieu, I

2001-05-01

Climate change may affect exposures to air pollutants by affecting weather, anthropogenic emissions, and biogenic emissions and by changing the distribution and types of airborne allergens. Local temperature, precipitation, clouds, atmospheric water vapor, wind speed, and wind direction influence atmospheric chemical processes, and interactions occur between local and global-scale environments. If the climate becomes warmer and more variable, air quality is likely to be affected. However, the specific types of change (i.e., local, regional, or global), the direction of change in a particular location (i.e., positive or negative), and the magnitude of change in air quality that may be attributable to climate change are a matter of speculation, based on extrapolating present understanding to future scenarios. There is already extensive evidence on the health effects of air pollution. Ground-level ozone can exacerbate chronic respiratory diseases and cause short-term reductions in lung function. Exposure to particulate matter can aggravate chronic respiratory and cardiovascular diseases, alter host defenses, damage lung tissue, lead to premature death, and possibly contribute to cancer. Health effects of exposures to carbon monoxide, sulfur dioxide, and nitrogen dioxide can include reduced work capacity, aggravation of existing cardiovascular diseases, effects on pulmonary function, respiratory illnesses, lung irritation, and alterations in the lung's defense systems. Adaptations to climate change should include ensuring responsiveness of air quality protection programs to changing pollution levels. Research needs include basic atmospheric science work on the association between weather and air pollutants; improving air pollution models and their linkage with climate change scenarios; and closing gaps in the understanding of exposure patterns and health effects.

Photonic band gap engineering in 2D photonic crystals

Indian Academy of Sciences (India)

-dimensional photonic crystals with square lattices composed of air holes in dielectric and vice versa i.e., dielectric rods in air, using the plane-wave expansion method are investigated. We then study, how the photonic band gap size is ...

A wind-tunnel investigation of wind-turbine wakes in different yawed and loading conditions

Science.gov (United States)

Bastankhah, Majid; Porté-Agel, Fernando

2015-04-01

Wind-turbine wakes have negative effects on wind-farm performance. They are associated with: (a) the velocity deficit, which reduces the generated power of downwind turbines; and (b) the turbulence level, which increases the fatigue loads on downwind turbines. Controlling the yaw angle of turbines can potentially improve the performance of wind farms by deflecting the wake away from downwind turbines. However, except for few studies, wakes of yawed turbines still suffer from the lack of systematic research. To fill this research gap, we performed wind-tunnel experiments in the recirculating boundary-layer wind tunnel at the WIRE Laboratory of EPFL to better understand the wakes of yawed turbines. High-resolution stereoscopic particle image-velocimetry (S-PIV) was used to measure three velocity components in a horizontal plane located downwind of a horizontal-axis, three-blade model turbine. A servo-controller was connected to the DC generator of the turbine, which allowed us to apply different loadings. The power and thrust coefficients of the turbine were also measured for each case. These power and thrust measurements together with the highly-resolved flow measurements enabled us to study different wake characteristics such as the energy entrainment from the outer flow into the wake, the wake deflection and the helicoidal tip vortices for yawed turbines.

Enhanced Freshwater Production Using Finned-Plate Air Gap Membrane Distillation (AGMD

Directory of Open Access Journals (Sweden)

Perves Bappy Mohammad Jabed

2017-01-01

Full Text Available Air Gap membrane distillation (AGMD, a special type of energy efficient membrane distillation process, is a technology for producing freshwater from waste water. Having some benefits over other traditional processes, this method has been able to draw attention of researchers working in the field of freshwater production technologies. In this study, a basic AGMD system with flat coolant plate has been modified using a specially designed channelled coolant plate of portable size to observe its effect over the production rate and performance of the system. Attempt has been made to increase the amount of distillate flux by using the “fin effect” of the channelled coolant plate. A finned plate have been used instead of a flat coolant plate and experiments were conducted to compare the effect. Coolant temperature and feed temperature of the system have been varied from 10°C to 25°C and 40°C to 70°C respectively. Comparing the data, around 50% to 58% distillate enhancement has been observed for channelled coolant plate. Also, it was seen that the enhancement was higher for higher feed temperatures and coolant temperatures. With these findings, a better performing AGMD module has been introduced to mitigate the scarcity of freshwater.

The use of Markov chains in forecasting wind speed: Matlab source code and applied case study

Directory of Open Access Journals (Sweden)

Ionuţ Alexandru Petre

2017-01-01

Full Text Available The ability to predict the wind speed has an important role for renewable energy industry which relies on wind speed forecasts in order to calculate the power a wind farm can produce in an area. There are several well-known methods to predict wind speed, but in this paper we focus on short-term wind forecasting using Markov chains. Often gaps can be found in the time series of the wind speed measurements and repeating the measurements is usually not a valid option. In this study it is shown that using Markov chains these gaps from the time series can be filled (they can be generated in an efficient way, but only when the missing data is for a short period of time. Also, the developed Matlab programms that are used in the case study, are included in the paper beeing presented and commented by the authors. In the case study data from a wind farm in Italy is used. The available data are as average wind speed at an interval of 10 minutes in the time period 11/23/2005 - 4/27/2006.

Electric wind produced by a surface dielectric barrier discharge operating in air at different pressures: aeronautical control insights

International Nuclear Information System (INIS)

Benard, N; Balcon, N; Moreau, E

2008-01-01

The effects of the ambient air pressure level on the electric wind produced by a single dielectric barrier discharge (DBD) have been investigated by Pitot velocity measurements. Pressures from 1 down to 0.2 atm were tested with a 32 kV p-p 1 kHz excitation. This preliminary study confirms the effectiveness of surface DBD at low pressure. Indeed, the induced velocity is strongly dependent on the ambient air pressure level. Quite surprisingly the produced airflow presents a local maximum at 0.6 atm. The measured velocities at 1 atm and 0.2 atm are 2.5 m s -1 and 3 m s -1 , respectively while 3.5 m s -1 is reached at 0.6 atm. The position of the maximal velocity always coincides with the plasma extension. Mass flow rate calculations indicate that the DBD is effective in real flight pressure conditions. (fast track communication)

Wind resource modelling for micro-siting - Validation at a 60-MW wind farm site

Energy Technology Data Exchange (ETDEWEB)

Hansen, J C; Gylling Mortensen, N [Risoe National Lab., Wind Energy and Atmospheric Physics Dept., Roskilde (Denmark); Said, U S [New and Renewable Energy Authority, Cairo (Egypt)

1999-03-01

This paper investigates and validates the applicability of the WAsP-model for layout optimization and micro-siting of wind turbines at a given site for a 60-MW wind farm at Zafarana at the Gulf of Suez in Egypt. Previous investigations show large gradients in the wind climate within the area. For the design and optimization of the wind farm it was found necessary to verify the WAsP extrapolation of wind atlas results from 2 existing meteorological masts located 5 and 10 km, respectively, from the wind farm site. On-site measurements at the 3.5 x 3.5 km{sup 2} wind farm site in combination with 7 years of near-site wind atlas measurements offer significant amounts of data for verification of wind conditions for micro-siting. Wind speeds, wind directions, turbulence intensities and guests in 47.5 m a.g.l. have been measured at 9 locations across the site. Additionally, one of the site masts is equipped as a reference mast, measuring both vertical profiles of wind speed and temperature as well as air pressure and temperature. The exercise is further facilitated by the fact that winds are highly uni-directional; the north direction accounting for 80-90% of the wind resource. The paper presents comparisons of 5 months of on-site measurements and modeled predictions from 2 existing meteorological masts located at distances of 5 and 10 km, respectively, from the wind farm site. Predictions based on terrain descriptions of the Wind Atlas for the Gulf of Suez 1991-95 showed over-predictions of wind speeds of 4-10%. With calibrated terrain descriptions, made based on measured data and a re-visit to critical parts of the terrain, the average prediction error of wind speeds was reduced to about 1%. These deviations are smaller than generally expected for such wind resource modeling, clearly documenting the validity of using WAsP modeling for micro-siting and layout optimization of the wind farm. (au)

Wind Energy Department: Scientific and technical progress 1999-2000

DEFF Research Database (Denmark)

2001-01-01

The activities of the Wind Energy Department fall within boundary layer meteorology, atmospheric turbulence, aerodynamics, aero-acoustics, structural dynamics, machine and construction technology and design of power systems and power system controls. Theobjective is to develop methods for design......; test and siting of wind turbines; prediction of wind loads and wind resources as well as methods to determine the dispersion, transformation and effect of air pollution. The present report describes theorganisation of the department and presents selected scientific highlights and results from the two...

Using Analog Ensemble to generate spatially downscaled probabilistic wind power forecasts

Science.gov (United States)

Delle Monache, L.; Shahriari, M.; Cervone, G.

2017-12-01

We use the Analog Ensemble (AnEn) method to generate probabilistic 80-m wind power forecasts. We use data from the NCEP GFS ( 28 km resolution) and NCEP NAM (12 km resolution). We use forecasts data from NAM and GFS, and analysis data from NAM which enables us to: 1) use a lower-resolution model to create higher-resolution forecasts, and 2) use a higher-resolution model to create higher-resolution forecasts. The former essentially increases computing speed and the latter increases forecast accuracy. An aggregated model of the former can be compared against the latter to measure the accuracy of the AnEn spatial downscaling. The AnEn works by taking a deterministic future forecast and comparing it with past forecasts. The model searches for the best matching estimates within the past forecasts and selects the predictand value corresponding to these past forecasts as the ensemble prediction for the future forecast. Our study is based on predicting wind speed and air density at more than 13,000 grid points in the continental US. We run the AnEn model twice: 1) estimating 80-m wind speed by using predictor variables such as temperature, pressure, geopotential height, U-component and V-component of wind, 2) estimating air density by using predictors such as temperature, pressure, and relative humidity. We use the air density values to correct the standard wind power curves for different values of air density. The standard deviation of the ensemble members (i.e. ensemble spread) will be used as the degree of difficulty to predict wind power at different locations. The value of the correlation coefficient between the ensemble spread and the forecast error determines the appropriateness of this measure. This measure is prominent for wind farm developers as building wind farms in regions with higher predictability will reduce the real-time risks of operating in the electricity markets.

Effect of high wind conditions on AHX performance for PFBR

International Nuclear Information System (INIS)

Goyal, P.; Datta, Anu; Verma, Vishnu; Singh, R.K.

2013-05-01

In case of normal shut down or station blackout condition the core decay heat is removed by Safety Grade Decay Heat Removal System (SGDHRS) in PFBR. The Prototype Fast Breeder Reactor (PFBR) is under construction at Kalpakkam. SGDHRS remove decay heat from the core and dissipate it into the environment with the help of Air Heat Exchanger (AHX). SGDHRS consists of four redundant numbers of totally independent circuits capable of removing decay heat from the hot pool through natural convection in the primary and intermediate sodium sides as well as in the air side. Each circuit consists of a sodium to sodium heat exchanger (DHX) and a sodium to AHX connected to intermediate sodium circuit, AHX is located at a higher elevation compared to DHX. AHX is serpentine type finned tube compact heat exchanger with sodium in the tube side and air flowing over finned tubes. A tall stack provides the driving force for the natural convection of air flow through the AHX, when the dampers are opened. The AHX is placed outside of Reactor Control Building (RCB), on the roof of Steam Generator Building. Due to the presence of nearby buildings around the stack, the AHX performance under high wind condition may be affected. A CFD simulation using CFD-ACE+ code has been carried in which effect of high wind condition and nearby building on AHX performance have been studied. For high wind condition various orientation of wind movement was considered for parametric studies. AHX performance for all the cases were compared with the results that obtained for the absence of nearby buildings. A comparative table was prepared to understand how the AHX performance is effected with the high wind condition for various direction and with the presence of nearby building. It was observed that AHX performance is influenced by high wind conditions in most of the cases for with and without presence of nearby building. Hence to ensure the optimal performance of the AHX under high wind conditions its

Environmental assessment: Kotzebue Wind Installation Project, Kotzebue, Alaska

International Nuclear Information System (INIS)

1998-05-01

The DOE is proposing to provide financial assistance to the Kotzebue Electric Association to expand its existing wind installation near Kotzebue, Alaska. Like many rural Alaska towns, Kotzebue uses diesel-powered generators to produce its electricity, the high cost of which is currently subsidized by the Alaska State government. In an effort to provide a cost effective and clean source of electricity, reduce dependence on diesel fuel, and reduce air pollutants, the DOE is proposing to fund an experimental wind installation to test commercially available wind turbines under Arctic conditions. The results would provide valuable information to other Alaska communities experiencing similar dependence on diesel-powered generators. The environmental assessment for the proposed wind installation assessed impacts to biological resources, land use, electromagnetic interference, coastal zone, air quality, cultural resources, and noise. It was determined that the project does not constitute a major Federal action significantly affecting the quality of the human environment. Therefore, the preparation of an environmental impact statement is not required, and DOE has issued a Finding of No Significant Impact

Environmental assessment: Kotzebue Wind Installation Project, Kotzebue, Alaska

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-05-01

The DOE is proposing to provide financial assistance to the Kotzebue Electric Association to expand its existing wind installation near Kotzebue, Alaska. Like many rural Alaska towns, Kotzebue uses diesel-powered generators to produce its electricity, the high cost of which is currently subsidized by the Alaska State government. In an effort to provide a cost effective and clean source of electricity, reduce dependence on diesel fuel, and reduce air pollutants, the DOE is proposing to fund an experimental wind installation to test commercially available wind turbines under Arctic conditions. The results would provide valuable information to other Alaska communities experiencing similar dependence on diesel-powered generators. The environmental assessment for the proposed wind installation assessed impacts to biological resources, land use, electromagnetic interference, coastal zone, air quality, cultural resources, and noise. It was determined that the project does not constitute a major Federal action significantly affecting the quality of the human environment. Therefore, the preparation of an environmental impact statement is not required, and DOE has issued a Finding of No Significant Impact.

Local non-market quality of life dynamics in new wind farms communities

International Nuclear Information System (INIS)

Kahn, Matthew E.

2013-01-01

The environmental benefits from generating electricity using renewable power are well known. Both wind farms and large scale solar installations require significant amounts of land to generate such power. Private land holders gain from leasing and selling land to renewable power generators but how are nearby neighbors and county residents affected? This study uses data from West Texas and documents that wind farm county's residents have gained from recent place based investments in wind farms. County property tax rates have fallen and public school quality has improved in those counties where wind farms have been built. Based on the local fiscal data, local school quality data and local ambient air pollution data, renewable power is a “better neighbor” than conventional fossil fuel fired power plants. - Highlights: • Rural counties with wind farms have lower property tax rates than neighbor counties. • Wind farm counties have lower student–teacher ratios. • Ambient air pollution levels are higher near fossil fuel fired power plants

Sage-Grouse and Wind Energy: Biology, Habits, and Potential Effects from Development

Energy Technology Data Exchange (ETDEWEB)

Becker, James M.; Tagestad, Jerry D.; Duberstein, Corey A.; Downs, Janelle L.

2009-07-15

Proposed development of domestic energy resources, including wind energy, is expected to impact the sagebrush steppe ecosystem in the western United States. The greater sage-grouse relies on habitats within this ecosystem for survival, yet very little is known about how wind energy development may affect sage-grouse. The purpose of this report is to inform organizations of the impacts wind energy development could have on greater sage-grouse populations and identify information needed to fill gaps in knowledge.

Design of airborne wind turbine and computational fluid dynamics analysis

Science.gov (United States)

Anbreen, Faiqa

Wind energy is a promising alternative to the depleting non-renewable sources. The height of the wind turbines becomes a constraint to their efficiency. Airborne wind turbine can reach much higher altitudes and produce higher power due to high wind velocity and energy density. The focus of this thesis is to design a shrouded airborne wind turbine, capable to generate 70 kW to propel a leisure boat with a capacity of 8-10 passengers. The idea of designing an airborne turbine is to take the advantage of higher velocities in the atmosphere. The Solidworks model has been analyzed numerically using Computational Fluid Dynamics (CFD) software StarCCM+. The Unsteady Reynolds Averaged Navier Stokes Simulation (URANS) with K-epsilon turbulence model has been selected, to study the physical properties of the flow, with emphasis on the performance of the turbine and the increase in air velocity at the throat. The analysis has been done using two ambient velocities of 12 m/s and 6 m/s. At 12 m/s inlet velocity, the velocity of air at the turbine has been recorded as 16 m/s. The power generated by the turbine is 61 kW. At inlet velocity of 6 m/s, the velocity of air at turbine increased to 10 m/s. The power generated by turbine is 25 kW.

Experimental Investigation of Aerodynamic Noise Generated by a Train-Car Gap

Science.gov (United States)

Mizushima, Fumio; Takakura, Hiroyuki; Kurita, Takeshi; Kato, Chisachi; Iida, Akiyoshi

To investigate the mechanism of noise generation by a train-car gap, which is one of a major source of noise in Shinkansen trains, experiments were carried out in a wind tunnel using a 1/5-scale model train. We measured velocity profiles of the boundary layer that approaches the gap and confirmed that the boundary layer is turbulent. We also measured the power spectrum of noise and surface pressure fluctuations around the train-car gap. Peak noise and broadband noise were observed. It is found that strong peak noise is generated when the vortex shedding frequency corresponds to the acoustic resonance frequency determined by the geometrical shape of the gap, and that broadband noise is generated at the downstream edge of the gap where vortexes collide. It is estimated that the convection velocity of the vortices in the gap is approximately 45% of the uniform flow velocity.

Wind Atlas Analysis and Application Program: WAsP 11 Help Facility

DEFF Research Database (Denmark)

2014-01-01

of specific wind turbines and wind farms. The WAsP Help Facility includes a Quick Start Tutorial, a User's Guide and a Technical Reference. It further includes descriptions of the Observed Wind Climate Wizard, the WAsP Climate Analyst, the WAsP Map Editor tool, the WAsP Turbine Editor tool, the Air Density...

Behavioral analyses of wind-evoked escape of the cricket, Gryllodes sigillatus.

Science.gov (United States)

Kanou, Masamichi; Konishi, Atsuko; Suenaga, Rie

2006-04-01

The wind-evoked escape behavior of the cricket Gryllodes sigillatus was investigated using an air puff stimulus. A high velocity air puff elicited the escape behavior in many crickets. The crickets tended to escape away from the stimulus source, but the direction was not accurately oriented 180 degrees from the stimulus. After bilateral cercal ablation, only a few crickets showed wind-evoked escape behavior, and their response rates did not increase even 19 days after ablation. Therefore, information on air motion detected by cercal filiform hairs is essential for triggering wind-evoked behavior. After unilateral cercal ablation, the 81.3% response rate of intact crickets decreased to 16.5%, that is, it decreased to almost 20% that of intact crickets. One week after unilateral cercal ablation, the response rate recovered to more than 60% that of intact crickets. However, the accuracy rate of the escape direction of G. sigillatus showed no change even immediately after the unilateral cercal ablation. Therefore, both cerci are not necessarily required to determine the escape direction. The behavioral characteristics of wind-evoked escape of G. sigillatus are compared with those of another species of cricket, Gryllus bimaculatus. The two species of cricket employ different strategies for wind-evoked escape.

Autonomous Aerial Sensors for Wind Power Meteorology

DEFF Research Database (Denmark)

Giebel, Gregor; Schmidt Paulsen, Uwe; Reuder, Joachim

2011-01-01

, UAVs could be quite cost-effective. In order to test this assumption and to test the limits of UAVs for wind power meteorology, this project assembles four different UAVs from four participating groups. Risø has built a lighter-than-air kite with a long tether, Bergen University flies a derivative......This paper describes a new approach for measurements in wind power meteorology using small unmanned flying platforms. Large-scale wind farms, especially offshore, need an optimisation between installed wind power density and the losses in the wind farm due to wake effects between the turbines. Good...... movement. In any case, a good LIDAR or SODAR will cost many tenthousands of euros. Another current problem in wind energy is the coming generation of wind turbines in the 10-12MW class, with tip heights of over 200m. Very few measurement masts exist to verify our knowledge of atmospheric physics, and most...

Pose and Wind Estimation for Autonomous Parafoils

Science.gov (United States)

2014-09-01

Precision Airdrop System LIDAR light detection and ranging LOP line of position MCADS Maritime Craft Air Delivery System MEMS micro-electro-mechanical...least squares SLAM simultaneous localization and mapping SPS standard positioning service TIP Turn Initiation Point TMA target motion analysis TNT...improvements and further testing on the WindPack [45]. Most recently, Herrmann proposed the use of a ground-based lidar wind measurement system to transmit

Exergy Analysis of Air-Gap Membrane Distillation Systems for Water Purification Applications

Directory of Open Access Journals (Sweden)

Daniel Woldemariam

2017-03-01

Full Text Available Exergy analyses are essential tools for the performance evaluation of water desalination and other separation systems, including those featuring membrane distillation (MD. One of the challenges in the commercialization of MD technologies is its substantial heat demand, especially for large scale applications. Identifying such heat flows in the system plays a crucial role in pinpointing the heat loss and thermal integration potential by the help of exergy analysis. This study presents an exergetic evaluation of air-gap membrane distillation (AGMD systems at a laboratory and pilot scale. A series of experiments were conducted to obtain thermodynamic data for the water streams included in the calculations. Exergy efficiency and destruction for two different types of flat-plate AGMD were analyzed for a range of feed and coolant temperatures. The bench scale AGMD system incorporating condensation plate with more favorable heat conductivity contributed to improved performance parameters including permeate flux, specific heat demand, and exergy efficiency. For both types of AGMD systems, the contributions of the major components involved in exergy destruction were identified. The result suggested that the MD modules caused the highest fraction of destructions followed by re-concentrating tanks.

Performing wind-tunnel modeling for better management of near-field risks

International Nuclear Information System (INIS)

Huang, Ju-Chrong; Weber, A.H.

1992-01-01

All industrial complexes must be able to demonstrate that air pollutant concentrations from normal and accidental releases are within the bounds of stringent acceptance criteria. The offsite concentrations are comparatively easy to compute with the standard Gaussian models. By contrast, the onsite (in particular, near-field) concentrations can be more complex since the wind flows can interact with various structures in complex ways to create regions of relatively high local concentrations. Three methods can be used to predict the air pollutant concentrations: (1) mathematical models, (2) field experiments, and (3) fluid models (wind-tunnel testing). The complex flow in the vicinity of buildings is not amenable to simple mathematical generalizations. Field experiments cannot encompass the wind spectrum of meteorological conditions in the time generally allotted. Wind tunnel testing works best where numerical models fail and field testing is not applicable. This paper covers the following aspects related to the wind-tunnel modeling studies: (1) planning strategies; (2) types of wind-tunnel modeling studies flow visualization and concentration measurement experiments; (3) highlights (video tape show) of the wind tunnel experiments; (4) technical challenges; and (5) various applications

Wind energy department: Scientific and technical progress 1999 - 2000

International Nuclear Information System (INIS)

Skrumsager, B.; Larsen, G.

2001-01-01

The activities of the Wind Energy Department fall within boundary layer meteorology, atmospheric turbulence, aerodynamics, aero-acoustics, structural dynamics, machine and construction technology and design of power systems and power system controls. The objective is to develop methods for design; test and siting of wind turbines; prediction of wind loads and wind resources as well as methods to determine the dispersion, transformation and effect of air pollution. The present report describes the organisation of the department and presents selected scientific highlights and results from the two-year period 1999-2000. (au)

Variation of boundary-layer wind spectra with height

DEFF Research Database (Denmark)

Larsén, Xiaoli Guo; Petersen, Erik L.; Larsen, Søren Ejling

2018-01-01

This study revisits the height dependence of the wind speed power spectrum from the synoptic scale to the spectral gap. Measurements from cup anemometers and sonics at heights of 15 m to 244 m are used. The measurements are from one land site, one coastal land‐based site and three offshore sites...... the atmospheric tide. The second finding regards the height dependence of the general spectrum. We describe the dependence through a so‐called effective roughness, which is calculated from wind spectra and represents the energy removal at different frequencies, and thus surface conditions in the footprint areas....... The generalizable spectral properties of winds presented herein may prove useful for validating numerical models....

Air pollution in a tropical city: the relationship between wind direction and lichen bio-indicators in San José, Costa Rica

Directory of Open Access Journals (Sweden)

Erich Neurohr Bustamante

2011-06-01

Full Text Available Lichens are good bio-indicators of air pollution, but in most tropical countries there are few studies on the subject; however, in the city of San José, Costa Rica, the relationship between air pollution and lichens has been studied for decades. In this article we evaluate the hypothesis that air pollution is lower where the wind enters the urban area (Northeast and higher where it exits San José (Southwest. We identified the urban parks with a minimum area of approximately 5 000m² and randomly selected a sample of 40 parks located along the passage of wind through the city. To measure lichen coverage, we applied a previously validated 10 x 20cm template with 50 random points to five trees per park (1.5m above ground, to the side with most lichens. Our results (years 2008 and 2009 fully agree with the generally accepted view that lichens reflect air pollution carried by circulating air masses. The practical implication is that the air enters the city relatively clean by the semi-rural and economically middle class area of Coronado, and leaves through the developed neighborhoods of Escazú and Santa Ana with a significant amount of pollutants. In the dry season, the live lichen coverage of this tropical city was lower than in the May to December rainy season, a pattern that contrasts with temperate habitats; but regardless of the season, pollution follows the pattern of wind movement through the city. Rev.Biol. Trop. 59 (2: 899-905. Epub 2011 June 01.Los líquenes constituyen un buen bioindicador para estudiar la “salud de la atmósfera”, pero en los países tropicales hay pocos estudios sobre el tema, aunque para la ciudad de San José existen algunos estudios sobre la relación entre tráfico vehicular y contaminación atmosférica. En este artículo evaluamos la hipótesis de que la contaminación atmosférica es menor en las áreas por donde ingresan los vientos a la zona urbana de San José (noreste y mayor a su salida (suroeste, para

A bi-annular-gap magnetorheological energy absorber for shock and vibration mitigation

Science.gov (United States)

Bai, Xian-Xu; Wereley, Norman M.; Choi, Young-Tai; Wang, Dai-Hua

2012-04-01

For semi-active shock and vibration mitigation systems using magnetorheological energy absorbers (MREAs), the minimization of the field-off damper force of the MREA at high speed is of particular significance because the damper force due to the viscous damping at high speed becomes too excessive and thus the controllable dynamic force range that is defined by the ratio of the field-on damper force to the field-off damper force is significantly reduced. In this paper, a bi-annular-gap MREA with an inner-set permanent magnet is proposed to decrease the field-off damper force at high speed while keeping appropriate dynamic force range for improving shock and vibration mitigation performance. In the bi-annular-gap MREA, two concentric annular gaps are configured in parallel so as to decrease the baseline damper force and both magnetic activation methods using the electromagnetic coil winding and the permanent magnet are used to keep holding appropriate magnetic intensity in these two concentric annular gaps in the consideration of failure of the electric power supply. An initial field-on damper force is produced by the magnetic field bias generated from the inner-set permanent magnet. The initial damper force of the MREA can be increased (or decreased) through applying positive (or negative) current to the electromagnetic coil winding inside the bi-annular-gap MREA. After establishing the analytical damper force model of the bi-annular-gap MREA using a Bingham-plastic nonlinear fluid model, the principle and magnetic properties of the MREA are analytically validated and analyzed via electromagnetic finite element analysis (FEA). The performance of the bi-annular-gap MREA is also theoretically compared with that of a traditional single-annular- gap MREA with the constraints of an identical volume by the performance matrix, such as the damper force, dynamic force range, and Bingham number with respect to different excitation velocities.

Experimental Constraints on γ-Ray Pulsar Gap Models and the Pulsar GeV to Pulsar Wind Nebula TeV Connection

Science.gov (United States)

Abeysekara, A. U.; Linnemann, J. T.

2015-05-01

The pulsar emission mechanism in the gamma ray energy band is poorly understood. Currently, there are several models under discussion in the pulsar community. These models can be constrained by studying the collective properties of a sample of pulsars, which became possible with the large sample of gamma ray pulsars discovered by the Fermi Large Area Telescope. In this paper we develop a new experimental multi-wavelength technique to determine the beaming factor ≤ft( {{f}{Ω }} \\right) dependance on spin-down luminosity of a set of GeV pulsars. This technique requires three input parameters: pulsar spin-down luminosity, pulsar phase-averaged GeV flux, and TeV or X-ray flux from the associated pulsar wind nebula (PWN). The analysis presented in this paper uses the PWN TeV flux measurements to study the correlation between {{f}{Ω }} and \\dot{E}. The measured correlation has some features that favor the Outer Gap model over the Polar Cap, Slot Gap, and One Pole Caustic models for pulsar emission in the energy range of 0.1-100 GeV, but one must keep in mind that these simulated models failed to explain many of the most important pulsar population characteristics. A tight correlation between the pulsar GeV emission and PWN TeV emission was also observed, which suggests the possibility of a linear relationship between the two emission mechanisms. In this paper we also discuss a possible mechanism to explain this correlation.

Convective heat transfer from rotating disks subjected to streams of air

CERN Document Server

aus der Wiesche, Stefan

2016-01-01

This Brief describes systematically results of research studies on a series of convective heat transfer phenomena from rotating disks in air crossflow. Phenomena described in this volume were investigated experimentally using an electrically heated disk placed in the test section of a wind tunnel. The authors describe findings in which transitions between different heat transfer regimes can occur in dependency on the involved Reynolds numbers and the angle of incidence, and that these transitions could be related to phenomenological Landau and Landau-de Gennes models. The concise volume closes a substantial gap in the scientific literature with respect to flow and heat transfer in rotating disk systems and provides a comprehensive presentation of new and recent results not previously published in book form.

Do Wind Turbines Affect Weather Conditions?: A Case Study in Indiana

Directory of Open Access Journals (Sweden)

Meghan F. Henschen

2011-01-01

Full Text Available Wind turbines are becoming increasingly widespread in the United States as the world looks for cleaner sources of energy. Scientists, policymakers, and citizens have strong opinions regarding the positive and negative effects of wind energy projects, and there is a great deal of misinformation about wind energy circulating on the Web and other media sources. The purpose of this study is to gain a better understanding of how the rotation of hundreds of turbines can influence local weather conditions within a wind farm and in the surrounding areas. This experiment measures temperature, atmospheric pressure, wind speed, wind direction, relative humidity, and evaporation with five weather instruments at Meadow Lake Wind Farm located in White, Jasper, and Benton Counties, Indiana, from November 4 through November 18, 2010. The data show that as wind passes throughout the wind farm, the air warms during the overnight and early morning hours and cools during daytime hours. Observed lower humidity rates and higher evaporation rates downwind also demonstrate that the air dries out as it travels through the wind farm. Further research over multiple seasons is necessary to examine the effects of warmer nighttime temperatures and drier conditions progressively downwind of the installation. Nevertheless, wind turbines did not negatively affect local weather patterns in our small-scale research and may actually prevent frost, which could have important positive implications for farmers by potentially prolonging the growing season.

The enigmatic wind of 55 Cygni

Czech Academy of Sciences Publication Activity Database

Haucke, M.; Kraus, Michaela; Venero, R.O.J.; Cidale, L.S.; Nickeler, Dieter Horst; Tomić, S.; Curé, M.

2013-01-01

Roč. 56, č. 1 (2013), s. 191-194 E-ISSN 1669-9521 R&D Projects: GA ČR(CZ) GAP209/11/1198 Institutional support: RVO:67985815 Keywords : line profiles * stellar wind * spectroscopic observin Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics http://www. astronomia argentina.org.ar/b56/2013baaa...56...191H.pdf

Storage of compressed air. A possibility for an enhanced utilization of wind energy?; Druckluftspeicherung. Ein Weg zur verstaerkten Windenergienutzung?

Energy Technology Data Exchange (ETDEWEB)

Kretschmer, Rutger [DREWAG - Stadtwerke Dresden GmbH, Dresden (Germany). Hauptabt. Vertrieb und Beschaffung

2008-07-01

The high prices for fossil energy sources are due to increasing demand, limited production quotas and exhaustion of strategically positioned deposits. Likewise the electricity prices increase to. High electricity tariffs improve the investment climate for renewable energies independently from the fuel costs. The positive development of the renewable energy is accompanied by serious disadvantages. Thus, the conditions for grid control and for the operation of fossil power stations deteriorate. The author of the contribution under consideration reports on the storage of compressed air as a possibility for the use of wind energy.

Experimental study on airflow fluctuation characteristic of an underfloor air supply terminal unit

Energy Technology Data Exchange (ETDEWEB)

Liu, Jinping [School of Electric Power, South China University of Technology, Guangzhou 510640 (China); State Key Laboratory of Subtropical Building Science, South China University of Technology, Guangzhou 510640 (China); Wu, Yanfang [Design Institute of Guangzhou Metro Corporation, Guangzhou 510010 (China)

2010-11-15

In order to investigate dynamic characteristic of underfloor air supply terminal unit, an IFV900A hot-wire anemometer was used to measure the corresponding velocity field. Turbulence intensity and power spectrum density exponent of air velocity signal were analyzed. The result showed that the outlet velocity distribution of underfloor air supply terminal unit was uniform. With increment of height, the velocity distribution trends to be uniform. Two velocity attenuation regions appear during airflow development. Turbulence intensity changes obviously with height. It is lower than that of mechanical wind. Turbulence intensity goes up with the increment of jetting distance. Power spectrum density exponent trends to the value of natural wind with increase of jetting distance and decrease of wind velocity. The exponent value approaches to the value of typical natural wind for the air velocity is 0.5 m/s under high supply air rate. With airflow diffusion, the fluctuation characteristic of airflow varies obviously with the jetting direction. The fluctuation characteristic of airflow changes to that of natural wind with the increase of height which can improve comfort of indoor environment. (author)

Hybrid winding concept for toroids

DEFF Research Database (Denmark)

Schneider, Henrik; Andersen, Thomas; Knott, Arnold

2013-01-01

and placement machinery. This opens up the possibility for both an automated manufacturing process and an automated production process of toroidal magnetics such as power inductors, filtering inductors, air core inductors, transformers etc. Both the proposed hybrid and the common wire wound winding...

Measuring Device for Air Speed in Macroporous Media and Its Application Inside Apple Storage Bins

Directory of Open Access Journals (Sweden)

Martin Geyer

2018-02-01

Full Text Available In cold storage facilities of fruit and vegetables, airflow is necessary for heat removal. The design of storage facilities influences the air speed in the surrounding of the product. Therefore, knowledge about airflow next to the product is important to plan the layout of cold stores adapted to the requirements of the products. A new sensing device (ASL, Air speed logger is developed for omnidirectional measurement of air speed between fruit or vegetables inside storage bins or in bulk. It consists of four interconnected plastic spheres with 80 mm diameter each, adapted to the size of apple fruit. In the free space between the spheres, silicon diodes are fixed for the airflow measurement based on a calorimetric principle. Battery and data logger are mounted inside the spheres. The device is calibrated in a wind tunnel in a measuring range of 0–1.3 m/s. Air speed measurements in fruit bulks on laboratory scale and in an industrial fruit store show air speeds in gaps between fruit with high stability at different airflow levels. Several devices can be placed between stored products for determination of the air speed distribution inside bulks or bin stacks in a storage room.

Photonic band gaps of porous solids

International Nuclear Information System (INIS)

Biswas, R.; Sigalas, M. M.; Subramania, G.; Soukoulis, C. M.; Ho, K.-M.

2000-01-01

Colloidal inverse photonic crystals composed of ordered lattices of air spheres in a high dielectric background are found to have three-dimensional photonic gaps for face-centered cubic, hexgaonal close-packed, and double hexagonal close-packed stacking sequences. Conditions for the occurrence of the complete gap are a sufficient dielectric contrast and a geometry near close packed. Although the lower pseudogaps of these stacking sequences differ, the lowest stop band in the stacking direction is insensitive to the stacking sequence; hence their experimental reflection should be similar. Transmission calculations with structural disorder show the lower pseudogap is relatively unaffected but the higher gap is very difficult to observe with moderate disorder. (c) 2000 The American Physical Society

The (R)evolution of China: Offshore Wind Diffusion

DEFF Research Database (Denmark)

Poulsen, Thomas; Hasager, Charlotte Bay

2017-01-01

This research presents an industry level gap analysis for Chinese offshore wind, which serves as a way to illuminate how China may fast track industry evolution. The research findings provide insight into how the Chinese government strongly and systematically decrees state-owned Chinese firms to ...

Time-resolved PIV measurements of the atmospheric boundary layer over wind-driven surface waves

Science.gov (United States)

Markfort, Corey; Stegmeir, Matt

2017-11-01

Complex interactions at the air-water interface result in two-way coupling between wind-driven surface waves and the atmospheric boundary layer (ABL). Turbulence generated at the surface plays an important role in aquatic ecology and biogeochemistry, exchange of gases such as oxygen and carbon dioxide, and it is important for the transfer of energy and controlling evaporation. Energy transferred from the ABL promotes the generation and maintenance of waves. A fraction of the energy is transferred to the surface mixed layer through the generation of turbulence. Energy is also transferred back to the ABL by waves. There is a need to quantify the details of the coupled boundary layers of the air-water system to better understand how turbulence plays a role in the interactions. We employ time-resolved PIV to measure the detailed structure of the air and water boundary layers under varying wind and wave conditions in the newly developed IIHR Boundary-Layer Wind-Wave Tunnel. The facility combines a 30-m long recirculating water channel with an open-return boundary layer wind tunnel. A thick turbulent boundary layer is developed in the 1 m high air channel, over the water surface, allowing for the study of boundary layer turbulence interacting with a wind-driven wave field.

MARE-WINT. New Materials and Reliability in Offshore Wind Turbine Technology

DEFF Research Database (Denmark)

This book provides a holistic, interdisciplinary overview of offshore wind energy, and is a must-read for advanced researchers. Topics, from the design and analysis of future turbines, to the decommissioning of wind farms, are covered. The scope of the work ranges from analytical, numerical...... and experimental advancements in structural and fluid mechanics, to novel developments in risk, safety & reliability engineering for offshore wind. The core objective of the current work is to make offshore wind energy more competitive, by improving the reliability, and operations and maintenance (O&M) strategies...... of wind turbines. The research was carried out under the auspices of the EU-funded project, MARE-WINT. The work seeks to bridge the gap between research and a rapidly-evolving industry....