Showing papers on "Wind profile power law published in 1992"
TL;DR: In this paper, the influence of variability in wind speed on the calculated gas transfer velocities and the possibility of chemical enhancement of CO2 exchange at low wind speeds over the ocean is illustrated using a quadratic dependence of gas exchange on wind speed.
Abstract: Relationships between wind speed and gas transfer, combined with knowledge of the partial pressure difference of CO2 across the air-sea interface are frequently used to determine the CO2 flux between the ocean and the atmosphere. Little attention has been paid to the influence of variability in wind speed on the calculated gas transfer velocities and the possibility of chemical enhancement of CO2 exchange at low wind speeds over the ocean. The effect of these parameters is illustrated using a quadratic dependence of gas exchange on wind speed which is fit through gas transfer velocities over the ocean determined by the natural-14C disequilibrium and the bomb-14C inventory methods. Some of the variability between different data sets can be accounted for by the suggested mechanisms, but much of the variation appears due to other causes. Possible causes for the large difference between two frequently used relationships between gas transfer and wind speed are discussed. To determine fluxes of gases other than CO2 across the air-water interface, the relevant expressions for gas transfer, and the temperature and salinity dependence of the Schmidt number and solubility of several gases of environmental interest are included in an appendix.
4,187 citations
TL;DR: In this article, the feasibility of a method to determine the wind speed reduction in the center of a large wind farm by means of simple boundary layer theory was investigated, and the simplest possible assumptions have been chosen.
318 citations
Patent•
17 Sep 1992
TL;DR: In this article, a controller and method for operating a variable speed turbine to better track wind speed fluctuations for greater efficiency in conversion of wind energy to electrical energy is described, where the controller controls the rotor speed in accordance with a wind speed supplied by a wind observer in order to approximately follow the varying wind speeds.
Abstract: A controller and method is disclosed for operating a variable speed turbine to better track wind speed fluctuations for greater efficiency in conversion of wind energy to electrical energy. The controller of the invention controls the rotor speed in accordance with a wind speed supplied by a wind observer in order to approximately follow the varying wind speeds. The wind observer predicts the average wind speed at a subsequent point in time over the cross-section presented to the wind by the wind turbine. The average wind speed is applied to a parameter schedule to determine desired values for rotor speed and torque which are used by arotor speed stabilizer to command a reference load torque. The load torque of the generator is controlled in accordance with the commanded load torque, and therefore the desired rotor speed is approximated. During operation, the wind speed prediction process is repeated at each subsequent time interval, and the load torque, and therefore rotor speed, is controlled accordingly. The wind observer calculates the aerodynamic torque and then calculates net torque. The wind speed is predicted as a function of the present (previously predicted) wind speed and correction terms including net torque and the difference between the predicted and actual rotor speed. The wind observer is useful whenever the wind turbine rotor is turning, whether or not it is producing power.
223 citations
TL;DR: A Fabry-Perot interferometer and image-plane detector system to be used as a receiver for a Doppler lidar and the potential of the system as a wind profiler in the troposphere, the stratosphere, and the mesosphere is considered.
Abstract: A Fabry-Perot interferometer and image-plane detector system to be used as a receiver for a Doppler lidar have been developed. This system incorporates the latest technology in multichannel detectors, and it is an important step toward the development of operational wind profiler systems for the atmosphere. The instrumentation includes a stable high-resolution optically contacted plane etalon and a multiring anode detector to scan the image plane of the Fabry-Perot interferometer spatially. The high wavelength resolution provided by the interferometer permits the aerosol and molecular components of the backscattered signal to be distinguished, and the Doppler shift of either component can then be used to determine the wind altitude profile. The receiver performance has been tested by measuring the wind profile in the boundary layer. The Fabry-Perot interferometer and image-plane detector characteristics are described and sample measurements are presented. The potential of the system as a wind profiler in the troposphere, the stratosphere, and the mesosphere is also considered.
70 citations
01 Nov 1992
TL;DR: In this article, the authors extended the numerical turbulence simulation (SNLWIND) developed by Veers to include all three components of the turbulent wind vector and configured the code to simulate the characteristics of turbulent wind fields upwind and downwind of a large wind farm.
Abstract: We have recently expanded the numerical turbulence simulation (SNLWIND) developed by Veers [1] to include all three components of the turbulent wind vector We have also configured the code to simulate the characteristics of turbulent wind fields upwind and downwind of a large wind farm, as well as over uniform, flat terrain Veers's original method only simulates the longitudinal component of the wind in neutral flow This paper overviews the development of spectral distribution, spatial coherence, and cross correlation models used to expired the SNLWIND code to include the three components of the turbulent wind over a range of atmospheric stabilities These models are based on extensive measurements of the turbulence characteristics immediately upwind and downwind of a large wind farm in San Gorgonio Pass, California
57 citations
TL;DR: In this paper, a quasi-steady model for predicting the influence of wind turbulence on the energy produced by a wind turbine is presented. But it is not shown that neglecting the coupled dynamic effects due to turbulence may result in over predictions.
53 citations
ENEA1
TL;DR: In this paper, the performances of some diffusion models are analyzed using concentration data measured at ground level up to 400 m from the emission point, in a series of diffusion tests conducted by U.S. National Oceanic and Atmospheric Administration (NOAA) under inversion conditions with light winds.
53 citations
TL;DR: In this article, the effects of varying the water temperature, wind speed, and wind stress on the values of backscatter were investigated using measurements of normalized radar cross sections of wind-generated waves, made at X band for both vertical and horizontal polarization for incidence angles 10, 28, 48, and 68 deg.
Abstract: The effects of varying the water temperature, wind speed, and wind stress on the values of backscatter were investigated using measurements of normalized radar cross sections of wind-generated waves, made at X band for both vertical and horizontal polarization for incidence angles 10, 28, 48, and 68 deg. The experiment was conducted using the Naval Research Laboratory wind-wave tank. Measurements made for a wide range of wind speeds and water temperatures are compared with results of backscattering models currently in use.
51 citations
TL;DR: In this article, the authors performed fundamental studies of wind loading on the roof of a 1:25 geometrical scale model of the Texas Tech University test building in a boundary-layer wind tunnel.
51 citations
TL;DR: In this article, a relationship for estimating the spectrum of the power delivered from multiple wind turbines from the spectrum delivered by a single wind turbine is derived. But it is assumed in the derivation that the wind power time series of each turbine is stationary and can be related to time series or neighboring wind turbines by a spatial coherence function.
Abstract: A relationship for estimating the spectrum of the power delivered from multiple wind turbines from the spectrum of the power delivered by a single wind turbine is derived. It is assumed in the derivation that the wind power time series of each wind turbine is stationary and can be related to time series or neighboring wind turbines by a spatial coherence function. The multiple wind turbine power spectra is derived for two cases: operation at rated power and operation at below rated power. The theoretical results are compared with measurement data, showing excellent agreement. >
48 citations
01 Jan 1992
TL;DR: In this paper, the results of the JOULE-0064 "Full-scale Measurements in Wind Turbine Arrays" campaign have been used to provide data for the validation of wake and wind farm models, which are being developed simultaneously.
Abstract: In the framework of the JOULE-0064 'Full-scale Measurements in Wind Turbine Arrays' in the period between June-November 1992 measurements have been performed in the Sexbierum Wind Farm The aim of the measurements is to provide data for the validation of wake and wind farm models, which are being developed simultaneously, and to provide input data for wind turbine load calculation programmes The campaign concerned measurement of the wind speed, turbulence and shear stress behind a single wind turbine at distances of 25,55 and 8 rotor diarneters, respectively Besides detailed measurements of the wind field, the power of the turbine was measured A database has been compiled containing 1-minute averaged values of the measured quantities The database was analysed using a two-dimensional bin analysis with respect to the undisturbed wind direction and wind speed The analysis contains horizontal and vertical profiles of the: - U-,V-, and W-component of the wind in the wake; - turbulence intensities in three directions and turbulent kinetic energy in the wake; - shear stresses u'v', u'w' and v'w' in the wake These quantities are presented both in dimensional as in non-dimensionalized form With the data base a useful set of data is created for the validation of wake and wind farm models
TL;DR: In this paper, the results obtained from the measurements of the characteristics of wind turbulence in urban areas through the use of ultrasonic anemometers are described, which is what which was gained from the year long observation extending from January 1990 through December 1990 and during two typhoons No. 8922 and No. 9011.
TL;DR: In this paper, a series of wind-tunnel experiments have been carried out on the effects of the corner shape of high-rise buildings on the pedestrian-level wind environment around them.
TL;DR: In this paper, the wind speeds and significant wave heights derived from the Geosat altimeter were validated by comparing with the data obtained at Japanese ocean data buoy stations, and an experimental equation was derived in order to correct this error for the present study.
Abstract: The wind speeds and the significant wave heights derived from the Geosat altimeter are validated by comparing with the data obtained at Japanese ocean data buoy stations. A systematic error is found in the altimeter wind speeds at high winds. An experimental equation is derived in order to correct this error for the present study. By using the corrected wind speeds and the wave heights, growth of wind waves with fetch in the Japan Sea under winter monsoon is investigated. The altimeter-derived nondimensional significant wave height and nondimensional fetch show good agreement with the empirical fetch graph formulas. Fetch variation of the wind speeds is also discussed in relation to the evolution of the turbulent boundary layer over wind waves by using the altimeter data.
TL;DR: In this article, the roughness length and zero plane displacement were estimated as 0.93 ± 0.35 m and 0.17 − 0.01 m, respectively, at four heights using the eddy correlation technique at a fallow savannah site in the Sahel.
Abstract: Vertical exchange of heat, moisture and momentum above the earth's surface depends strongly on the turbulence generated by surface roughness. This roughness is best specified through the roughness length and the zero plane displacement. The ratio of windspeed to friction velocity was measured at four heights using the eddy correlation technique at a fallow savannah site in the Sahel. The change in this ratio with height was used to derive the zero plane displacement and the roughness length of the surface, together with an estimate of the error in each parameter. These were estimated as 0.93 ± 0.35 m and 0.17 ± 0.01 m, respectively. The method appears to be a more robust alternative to wind profile derivation.
TL;DR: In this paper, a simulation of wind gust was tried in a Eiffel type wind tunnel by an active control technique, where along-wind and vertical gusts were obtained by driving arrays of plates and airfoils, respectively, in a 2D wind tunnel.
TL;DR: In this article, the results of the experiments are presented as the wind pressure coefficient difference between windward and leeward in a model and various layouts of buildings are mainly discussed.
TL;DR: In this article, a low-rise building was measured at a position sufficiently far up-stream to be unaffected by the building's pressure field and spectral analysis of the measurements showed that the mean streamwise velocity profile is well represented by a log-law but that velocity spectra, espcially close to the ground, depart from the expected form in the inertial sub-range.
TL;DR: In this paper, the authors focused on the interaction of the solar wind only with the anomalous cosmic-ray component and derived numerical solutions in the following steps: first, they calculate an aspherical pressure distribution for the anomalies, describing their diffusion in an unperturbed radial solar wind Second, they then consider the perturbation of solar wind flow due to these induced anomalous Cosmic-ray pressure gradients, which may lead to pronounced upwinddownwind asymmetries in the pressures and thereby in the resulting solar wind flows.
Abstract: It is well known that both the galactic and anomalous cosmic rays show positive intensity gradients in the outer heliosphere which are connected with corresponding pressure gradients Due to an efficient dynamical coupling between the solar wind plasma and these highly energetic media by means of convected MHD turbulences, there exists a mutual interaction between these media As one consequence of this scenario the enforced pressure gradients influence the distant solar wind expansion Here we concentrate in our theoretical study on the interaction of the solar wind only with the anomalous cosmic-ray component We use the standard two-fluid model in which the cosmic-ray fluid modifies the solar wind flow via the cosmic-ray pressure gradient Then we derive numerical solutions in the following steps: first we calculate an aspherical pressure distribution for the anomalous cosmic rays, describing their diffusion in an unperturbed radial solar wind Second, we then consider the perturbation of the solar wind flow due to these induced anomalous cosmic-ray pressure gradients Within this context we especially take account of the action of a non-spherical geometry of the heliospheric shock which may lead to pronounced upwinddownwind asymmetries in the pressures and thereby in the resulting solar wind flows As we can show in our model, which fits the available observational data, radial decelerations of the distant solar wind by between 5 to 11% are to be expected, however, the deviations of the bulk solar wind flow from the radialdirections are only slightly pronounced
TL;DR: In this article, the surface drift current is gradually intensified by the swell propagating against the wind when the swell steepness increases, and the maximum increase of surface drift velocity caused by the opposing swell is about 46% of the surface drifting velocity for pure wind-waves at the same wind speed.
Abstract: Systematic measurements of the surface drift current, the wind profile over the water surface and the wave spectra have been made for (i) pure wind-waves, (ii) a co-existing system of wind-waves and swell propagating against the wind, and (iii) a co-existing system of wind-waves and swell propagating in the direction of the wind. The surface drift current is gradually intensified by the swell propagating against the wind when the swell steepness increases. The maximum increase of the surface drift velocity caused by the opposing swell is about 46% of the surface drift velocity for pure wind-waves at the same wind speed. Such a phenomenon was not observed when the swell was propagating in the direction of the wind.
TL;DR: In this article, the authors developed a protocol for retrieving the zonal wind profile from the Doppler shift of the measured frequency; assess the impact of a wide range of error sources on the accuracy of retrieved wind profile; and perform a number of simulations to illustrate their technique and to assess the likely accuracy of the retrieval.
Abstract: Ultrastable oscillators onboard the Galileo Probe and Orbiter will permit very accurate determinations of the frequency of the Probe’s telemetry signal as the Probe descends from a pressure level of several hundred mb to a level of about 20 bars. Analysis of the time-varying frequency can provide, in principle, a unique and important definition of the vertical profile of the zonal wind speed in the Jovian atmosphere. In this paper, we develop a protocol for retrieving the zonal wind profile from the Doppler shift of the measured frequency; assess the impact of a wide range of error sources on the accuracy of the retrieved wind profile; and perform a number of simulations to illustrate our technique and to assess the likely accuracy of the retrieval.
TL;DR: In this article, a boundary-layer wind tunnel with 1/100 scaled barriers at five spacings and four porosities modelled full scale shelter systems, and a hot-wire anemometer probe measured wind speeds.
TL;DR: In this paper, different types of vertical axis wind turbines (VAWT) are compared and compared as regards their aerodynamic performances. And the work-exchange between the wind flow and the machine is investigated by defining an internal efficiency of the wind turbine.
TL;DR: In this paper, a comparison with the data of the automatic weather stations located on the Reeves and the Priestley glaciers as well on the Nansen Ice Sheet has been used to model the dynamics of the Antarctic boundary layer.
Abstract: In the Antarctic boundary layer, some phenomena appear to be particularly enhanced with respect to those at midlatitudes. Thermal stratifications are present almost all year and can substain drainage flows of different types. Several episodes of flows with different potential temperature and consequently with different buoyancy were observed on the Nansen Ice Sheet by a sodar. Two case studies are presented in which a comparison with the data of the automatic weather stations located on the Reeves and the Priestley glaciers as well on the Nansen Ice Sheet have been used. As a main result, we saw that during the summer time, the flow from the Reeves glacier may superimpose the one from the Priestley, in contrast with the current opinion based on the automatic weather station measurements averaged over the entire year. Also, an episode of barrier-katabatic flow interaction is shown in which the first is negatively buoyant in comparison with the second. Since the wind profile frequently showed a great variability with height, the importance of using remote sensing sensors in studies that realistically want to model the dynamics of the Antarctic boundary layer has been emphasized. DOI: 10.1034/j.1600-0889.1992.00017.x
TL;DR: In this paper, the mean wind speed at K13 platform, near the Dutch coast, with a database of 8 years with wind speed measurements at one height, and the other one, the West Sole platform near the English coast, had only 1 year, but with both wind speed and turbulence intensity measurements at seven heights.
TL;DR: In this paper, the authors investigated the wake effects of wind turbines, which are determined by the wind pattern, and found that a large increase in the flapwise blade load fluctuations is found.
TL;DR: In this paper, the surface pressure distribution acting on two hyperbolic cooling towers at different gap-ratios under different wind directions by wind tunnel model test in simulated atmospheric boundary layer stream is presented.
TL;DR: In this paper, the authors present preliminary results of an experimental study conducted at the summit of a hill surrounded by complex terrain, where the objective of the experiment has been to increase the understanding of the characteristics of the wind field over hilly complex terrain for use in wind energy applications.
TL;DR: In this article, a multi-parametric wake model based on a combination of existing vortex, viscous and similarity models was proposed to predict the wake effects in wind farms, and the effect of the initial velocity profile on the wake development was investigated for the Nibe wind turbine.
TL;DR: In this paper, the wind data of several measurement sites in Somalia have been analyzed in order to characterize the wind potentiality in relation to the type of wind generators; these have been defined by a simple model of the system output.