WorldWideScience

Sample records for wind velocities measured

  1. ALADIN: an atmospheric laser Doppler wind lidar instrument for wind velocity measurements from space

    Science.gov (United States)

    Krawczyk, R.; Ghibaudo, JB.; Labandibar, JY.; Willetts, D.; Vaughan, M.; Pearson, G.; Harris, M.; Flamant, P. H.; Salamitou, P.; Dabas, A.; Charasse, R.; Midavaine, T.; Royer, M.; Heimel, H.

    2018-04-01

    This paper, "ALADIN: an atmospheric laser Doppler wind lidar instrument for wind velocity measurements from space," was presented as part of International Conference on Space Optics—ICSO 1997, held in Toulouse, France.

  2. Velocity measurement of model vertical axis wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, D.A.; McWilliam, M. [Waterloo Univ., ON (Canada). Dept. of Mechanical Engineering

    2006-07-01

    An increasingly popular solution to future energy demand is wind energy. Wind turbine designs can be grouped according to their axis of rotation, either horizontal or vertical. Horizontal axis wind turbines have higher power output in a good wind regime than vertical axis turbines and are used in most commercial class designs. Vertical axis Savonius-based wind turbine designs are still widely used in some applications because of their simplistic design and low wind speed performance. There are many design variables that must be considered in order to optimize the power output in a given wind regime in a typical wind turbine design. Using particle image velocimetry, a study of the air flow around five different model vertical axis wind turbines was conducted in a closed loop wind tunnel. A standard Savonius design with two semi-circular blades overlapping, and two variations of this design, a deep blade and a shallow blade design were among the turbine models included in this study. It also evaluated alternate designs that attempt to increase the performance of the standard design by allowing compound blade curvature. Measurements were collected at a constant phase angle and also at random rotor orientations. It was found that evaluation of the flow patterns and measured velocities revealed consistent and stable flow patterns at any given phase angle. Large scale flow structures are evident in all designs such as vortices shed from blade surfaces. An important performance parameter was considered to be the ability of the flow to remain attached to the forward blade and redirect and reorient the flow to the following blade. 6 refs., 18 figs.

  3. Method for Estimating Evaporative Potential (IM/CLO) from ASTM Standard Single Wind Velocity Measures

    Science.gov (United States)

    2016-08-10

    IM/CLO) FROM ASTM STANDARD SINGLE WIND VELOCITY MEASURES DISCLAIMER The opinions or assertions contained herein are the private views of the...USARIEM TECHNICAL REPORT T16-14 METHOD FOR ESTIMATING EVAPORATIVE POTENTIAL (IM/CLO) FROM ASTM STANDARD SINGLE WIND VELOCITY... ASTM STANDARD SINGLE WIND VELOCITY MEASURES Adam W. Potter Biophysics and Biomedical Modeling Division U.S. Army Research Institute of Environmental

  4. Ten years statistics of wind direction and wind velocity measurements performed at the Karlsruhe Nuclear Research Center

    International Nuclear Information System (INIS)

    Becker, M.; Dilger, H.

    1979-06-01

    The measurements of wind direction and wind velocity performed at 60 m and 200 m height were evaluated for one year each and frequency distributions of the measured values were established. The velocity was divided into 1 m/s steps and the direction into 10 0 sectors. The frequency distribution of the wind direction reveals three maxima located in the southwest, northeast and north, respectively. The maximum of the frequency distribution of the wind velocity occurs between 4 and 5 m/s at 200 m height and between 3 and 4 m/s at 60 m height. (orig.) [de

  5. Estimating random transverse velocities in the fast solar wind from EISCAT Interplanetary Scintillation measurements

    Directory of Open Access Journals (Sweden)

    A. Canals

    2002-09-01

    Full Text Available Interplanetary scintillation measurements can yield estimates of a large number of solar wind parameters, including bulk flow speed, variation in bulk velocity along the observing path through the solar wind and random variation in transverse velocity. This last parameter is of particular interest, as it can indicate the flux of low-frequency Alfvén waves, and the dissipation of these waves has been proposed as an acceleration mechanism for the fast solar wind. Analysis of IPS data is, however, a significantly unresolved problem and a variety of a priori assumptions must be made in interpreting the data. Furthermore, the results may be affected by the physical structure of the radio source and by variations in the solar wind along the scintillation ray path. We have used observations of simple point-like radio sources made with EISCAT between 1994 and 1998 to obtain estimates of random transverse velocity in the fast solar wind. The results obtained with various a priori assumptions made in the analysis are compared, and we hope thereby to be able to provide some indication of the reliability of our estimates of random transverse velocity and the variation of this parameter with distance from the Sun.Key words. Interplanetary physics (MHD waves and turbulence; solar wind plasma; instruments and techniques

  6. Estimating random transverse velocities in the fast solar wind from EISCAT Interplanetary Scintillation measurements

    Directory of Open Access Journals (Sweden)

    A. Canals

    Full Text Available Interplanetary scintillation measurements can yield estimates of a large number of solar wind parameters, including bulk flow speed, variation in bulk velocity along the observing path through the solar wind and random variation in transverse velocity. This last parameter is of particular interest, as it can indicate the flux of low-frequency Alfvén waves, and the dissipation of these waves has been proposed as an acceleration mechanism for the fast solar wind. Analysis of IPS data is, however, a significantly unresolved problem and a variety of a priori assumptions must be made in interpreting the data. Furthermore, the results may be affected by the physical structure of the radio source and by variations in the solar wind along the scintillation ray path. We have used observations of simple point-like radio sources made with EISCAT between 1994 and 1998 to obtain estimates of random transverse velocity in the fast solar wind. The results obtained with various a priori assumptions made in the analysis are compared, and we hope thereby to be able to provide some indication of the reliability of our estimates of random transverse velocity and the variation of this parameter with distance from the Sun.

    Key words. Interplanetary physics (MHD waves and turbulence; solar wind plasma; instruments and techniques

  7. EISCAT measurements of solar wind velocity and the associated level of interplanetary scintillation

    Directory of Open Access Journals (Sweden)

    R. A. Fallows

    2002-09-01

    Full Text Available A relative scintillation index can be derived from EISCAT observations of Interplanetary Scintillation (IPS usually used to study the solar wind velocity. This provides an ideal opportunity to compare reliable measurements of the solar wind velocity derived for a number of points along the line-of-sight with measurements of the overall level of scintillation. By selecting those occasions where either slow- or fast-stream scattering was dominant, it is shown that at distances from the Sun greater than 30 RS , in both cases the scintillation index fell with increasing distance as a simple power law, typically as R-1.7. The level of scintillation for slow-stream scattering is found to be 2.3 times the level for fast-stream scattering.Key words. Interplanetary physics (solar wind plasma

  8. Spectroscopic Measurements of the Ion Velocity Distribution at the Base of the Fast Solar Wind

    Science.gov (United States)

    Jeffrey, Natasha L. S.; Hahn, Michael; Savin, Daniel W.; Fletcher, Lyndsay

    2018-03-01

    In situ measurements of the fast solar wind reveal non-thermal distributions of electrons, protons, and minor ions extending from 0.3 au to the heliopause. The physical mechanisms responsible for these non-thermal properties and the location where these properties originate remain open questions. Here, we present spectroscopic evidence, from extreme ultraviolet spectroscopy, that the velocity distribution functions (VDFs) of minor ions are already non-Gaussian at the base of the fast solar wind in a coronal hole, at altitudes of thermal equilibrium, (b) fluid motions such as non-Gaussian turbulent fluctuations or non-uniform wave motions, or (c) some combination of both. These observations provide important empirical constraints for the source region of the fast solar wind and for the theoretical models of the different acceleration, heating, and energy deposition processes therein. To the best of our knowledge, this is the first time that the ion VDF in the fast solar wind has been probed so close to its source region. The findings are also a timely precursor to the upcoming 2018 launch of the Parker Solar Probe, which will provide the closest in situ measurements of the solar wind at approximately 0.04 au (8.5 solar radii).

  9. Vertical wind velocity measurements using a five-hole probe with remotely piloted aircraft to study aerosol–cloud interactions

    Directory of Open Access Journals (Sweden)

    R. Calmer

    2018-05-01

    Full Text Available The importance of vertical wind velocities (in particular positive vertical wind velocities or updrafts in atmospheric science has motivated the need to deploy multi-hole probes developed for manned aircraft in small remotely piloted aircraft (RPA. In atmospheric research, lightweight RPAs ( <  2.5 kg are now able to accurately measure atmospheric wind vectors, even in a cloud, which provides essential observing tools for understanding aerosol–cloud interactions. The European project BACCHUS (impact of Biogenic versus Anthropogenic emissions on Clouds and Climate: towards a Holistic UnderStanding focuses on these specific interactions. In particular, vertical wind velocity at cloud base is a key parameter for studying aerosol–cloud interactions. To measure the three components of wind, a RPA is equipped with a five-hole probe, pressure sensors, and an inertial navigation system (INS. The five-hole probe is calibrated on a multi-axis platform, and the probe–INS system is validated in a wind tunnel. Once mounted on a RPA, power spectral density (PSD functions and turbulent kinetic energy (TKE derived from the five-hole probe are compared with sonic anemometers on a meteorological mast. During a BACCHUS field campaign at Mace Head Atmospheric Research Station (Ireland, a fleet of RPAs was deployed to profile the atmosphere and complement ground-based and satellite observations of physical and chemical properties of aerosols, clouds, and meteorological state parameters. The five-hole probe was flown on straight-and-level legs to measure vertical wind velocities within clouds. The vertical velocity measurements from the RPA are validated with vertical velocities derived from a ground-based cloud radar by showing that both measurements yield model-simulated cloud droplet number concentrations within 10 %. The updraft velocity distributions illustrate distinct relationships between vertical cloud fields in different meteorological

  10. Vertical wind velocity measurements using a five-hole probe with remotely piloted aircraft to study aerosol-cloud interactions

    Science.gov (United States)

    Calmer, Radiance; Roberts, Gregory C.; Preissler, Jana; Sanchez, Kevin J.; Derrien, Solène; O'Dowd, Colin

    2018-05-01

    The importance of vertical wind velocities (in particular positive vertical wind velocities or updrafts) in atmospheric science has motivated the need to deploy multi-hole probes developed for manned aircraft in small remotely piloted aircraft (RPA). In atmospheric research, lightweight RPAs ( power spectral density (PSD) functions and turbulent kinetic energy (TKE) derived from the five-hole probe are compared with sonic anemometers on a meteorological mast. During a BACCHUS field campaign at Mace Head Atmospheric Research Station (Ireland), a fleet of RPAs was deployed to profile the atmosphere and complement ground-based and satellite observations of physical and chemical properties of aerosols, clouds, and meteorological state parameters. The five-hole probe was flown on straight-and-level legs to measure vertical wind velocities within clouds. The vertical velocity measurements from the RPA are validated with vertical velocities derived from a ground-based cloud radar by showing that both measurements yield model-simulated cloud droplet number concentrations within 10 %. The updraft velocity distributions illustrate distinct relationships between vertical cloud fields in different meteorological conditions.

  11. Field measurements of horizontal forward motion velocities of terrestrial dust devils: Towards a proxy for ambient winds on Mars and Earth

    Science.gov (United States)

    Balme, M. R.; Pathare, A.; Metzger, S. M.; Towner, M. C.; Lewis, S. R.; Spiga, A.; Fenton, L. K.; Renno, N. O.; Elliott, H. M.; Saca, F. A.; Michaels, T. I.; Russell, P.; Verdasca, J.

    2012-11-01

    Dust devils - convective vortices made visible by the dust and debris they entrain - are common in arid environments and have been observed on Earth and Mars. Martian dust devils have been identified both in images taken at the surface and in remote sensing observations from orbiting spacecraft. Observations from landing craft and orbiting instruments have allowed the dust devil translational forward motion (ground velocity) to be calculated, but it is unclear how these velocities relate to the local ambient wind conditions, for (i) only model wind speeds are generally available for Mars, and (ii) on Earth only anecdotal evidence exists that compares dust devil ground velocity with ambient wind velocity. If dust devil ground velocity can be reliably correlated to the ambient wind regime, observations of dust devils could provide a proxy for wind speed and direction measurements on Mars. Hence, dust devil ground velocities could be used to probe the circulation of the martian boundary layer and help constrain climate models or assess the safety of future landing sites. We present results from a field study of terrestrial dust devils performed in the southwest USA in which we measured dust devil horizontal velocity as a function of ambient wind velocity. We acquired stereo images of more than a 100 active dust devils and recorded multiple size and position measurements for each dust devil. We used these data to calculate dust devil translational velocity. The dust devils were within a study area bounded by 10 m high meteorology towers such that dust devil speed and direction could be correlated with the local ambient wind speed and direction measurements. Daily (10:00-16:00 local time) and 2-h averaged dust devil ground speeds correlate well with ambient wind speeds averaged over the same period. Unsurprisingly, individual measurements of dust devil ground speed match instantaneous measurements of ambient wind speed more poorly; a 20-min smoothing window applied to

  12. Demonstration of synchronised scanning Lidar measurements of 2D velocity fields in a boundary-layer wind tunnel

    DEFF Research Database (Denmark)

    van Dooren, M F; Kühn, M.; Petrovic, V.

    2016-01-01

    This paper combines the currently relevant research methodologies of scaled wind turbine model experiments in wind tunnels with remote-sensing short-range WindScanner Lidar measurement technology. The wind tunnel of the Politecnico di Milano was equipped with three wind turbine models and two short...... compared to hot wire probe measurements commonly used in wind tunnels. This yielded goodness of fit coefficients of 0.969 and 0.902 for the 1 Hz averaged u- and v-components of the wind speed, respectively, validating the 2D measurement capability of the Lidar scanners. Subsequently, the measurement...... for accurately measuring small scale flow structures in a wind tunnel....

  13. Measurement of velocity distribution and turbulence in a special wind tunnel using a laser Doppler velocimeter

    Science.gov (United States)

    Mueller, J.; Petersen, J. C.; Pilz, E.; Wiegand, H.

    1981-06-01

    The flow behavior in a jet mixing visualization chamber for turbulent fuel spray mixing with air under compression, e.g., at top dead center in diesel engines, was investigated with a laser Doppler velocimeter. The measurements were performed in two cuts in the profile perpendicular to the flow direction. The range of flow conditions in the measuring chamber was tested. The measurements were conducted with and without turbulence grids and shear flow grids behind the inlet nozzle. Wire grids did not enhance the turbulence in the measuring chamber. One of the tested shear flow grids produced shear flow as expected. A turbulence grid whose design was based on experimental results, produced a turbulence degree of up to 30% over the whole measuring cross section.

  14. Wave Tank Studies of Phase Velocities of Short Wind Waves

    Science.gov (United States)

    Ermakov, S.; Sergievskaya, I.; Shchegolkov, Yu.

    Wave tank studies of phase velocities of short wind waves have been carried out using Ka-band radar and an Optical Spectrum Analyser. The phase velocities were retrieved from measured radar and optical Doppler shifts, taking into account measurements of surface drift velocities. The dispersion relationship was studied in centimetre (cm)- and millimetre(mm)-scale wavelength ranges at different fetches and wind speeds, both for a clean water surface and for water covered with surfactant films. It is ob- tained that the phase velocities do not follow the dispersion relation of linear capillary- gravity waves, increasing with fetch and, therefore, depending on phase velocities of dominant decimetre (dm)-centimetre-scale wind waves. One thus can conclude that nonlinear cm-mm-scale harmonics bound to the dominant wind waves and propagat- ing with the phase velocities of the decimetric waves are present in the wind wave spectrum. The resulting phase velocities of short wind waves are determined by re- lation between free and bound waves. The relative intensity of the bound waves in the spectrum of short wind waves is estimated. It is shown that this relation depends strongly on the surfactant concentration, because the damping effect due to films is different for free and bound waves; this results to changes of phase velocities of wind waves in the presence of surfactant films. This work was supported by MOD, UK via DERA Winfrith (Project ISTC 1774P) and by RFBR (Project 02-05-65102).

  15. Vega-1 and Vega-2: vertical profiles of wind velocity according to Doppler measurements data at landing spacecrafts

    International Nuclear Information System (INIS)

    Kerzhanovich, V.V.; Antsibor, N.M.; Bakit'ko, R.V.

    1987-01-01

    Results of the measurements of the Venus atmosphere vertical motion using the ''Vega'' landing spacecrafts are presented. Signal emitted by the landing spacecraft transmitter was received by flying apparatus and retranslated to the Earth. The difference between the measured frequency of the retranslated signal and reference one (Doppler's shift) permitted to determine the velocity of the landing spacecraft with the accuracy of 2 cm/s with the pitch of 1 s

  16. Can Wind Lidars Measure Turbulence?

    DEFF Research Database (Denmark)

    Sathe, Ameya; Mann, Jakob; Gottschall, Julia

    2011-01-01

    Modeling of the systematic errors in the second-order moments of wind speeds measured by continuous-wave (ZephIR) and pulsed (WindCube) lidars is presented. These lidars use the conical scanning technique to measure the velocity field. The model captures the effect of volume illumination and coni...

  17. Characteristics of the Taylor microscale in the solar wind/foreshock. Magnetic field and electron velocity measurements

    Energy Technology Data Exchange (ETDEWEB)

    Gurgiolo, C. [Bitterroot Basic Research, Hamilton, MT (United States); Goldstein, M.L.; Vinas, A. [NASA Goddard Space Flight Center, Greenbelt, MD (United States). Heliospheric Physics Lab.; Matthaeus, W.H. [Delaware Univ., Newark, DE (United States). Bartol Research Foundation; Fazakerley, A.N. [University College London, Dorking (United Kingdom). Mullard Space Science Lab.

    2013-07-01

    The Taylor microscale is one of the fundamental turbulence scales. Not easily estimated in the interplanetary medium employing single spacecraft data, it has generally been studied through two point correlations. In this paper we present an alternative, albeit mathematically equivalent, method for estimating the Taylor microscale ({lambda}{sub T}). We make two independent determinations employing multi-spacecraft data sets from the Cluster mission, one using magnetic field data and a second using electron velocity data. Our results using the magnetic field data set yields a scale length of 1538{+-}550 km, slightly less than, but within the same range as, values found in previous magnetic-field-based studies. During time periods where both magnetic field and electron velocity data can be used, the two values can be compared. Relative comparisons show {lambda}{sub T} computed from the velocity is often significantly smaller than that from the magnetic field data. Due to a lack of events where both measurements are available, the absolute {lambda}{sub T} based on the electron fluid velocity is not able to be determined.

  18. Characteristics of the Taylor microscale in the solar wind/foreshock: magnetic field and electron velocity measurements

    Directory of Open Access Journals (Sweden)

    C. Gurgiolo

    2013-11-01

    Full Text Available The Taylor microscale is one of the fundamental turbulence scales. Not easily estimated in the interplanetary medium employing single spacecraft data, it has generally been studied through two point correlations. In this paper we present an alternative, albeit mathematically equivalent, method for estimating the Taylor microscale (λT. We make two independent determinations employing multi-spacecraft data sets from the Cluster mission, one using magnetic field data and a second using electron velocity data. Our results using the magnetic field data set yields a scale length of 1538 ± 550 km, slightly less than, but within the same range as, values found in previous magnetic-field-based studies. During time periods where both magnetic field and electron velocity data can be used, the two values can be compared. Relative comparisons show λT computed from the velocity is often significantly smaller than that from the magnetic field data. Due to a lack of events where both measurements are available, the absolute λT based on the electron fluid velocity is not able to be determined.

  19. Characteristics of the Taylor microscale in the solar wind/foreshock. Magnetic field and electron velocity measurements

    International Nuclear Information System (INIS)

    Gurgiolo, C.; Goldstein, M.L.; Vinas, A.; Matthaeus, W.H.; Fazakerley, A.N.

    2013-01-01

    The Taylor microscale is one of the fundamental turbulence scales. Not easily estimated in the interplanetary medium employing single spacecraft data, it has generally been studied through two point correlations. In this paper we present an alternative, albeit mathematically equivalent, method for estimating the Taylor microscale (λ T ). We make two independent determinations employing multi-spacecraft data sets from the Cluster mission, one using magnetic field data and a second using electron velocity data. Our results using the magnetic field data set yields a scale length of 1538±550 km, slightly less than, but within the same range as, values found in previous magnetic-field-based studies. During time periods where both magnetic field and electron velocity data can be used, the two values can be compared. Relative comparisons show λ T computed from the velocity is often significantly smaller than that from the magnetic field data. Due to a lack of events where both measurements are available, the absolute λ T based on the electron fluid velocity is not able to be determined.

  20. Effects of wind velocity and slope on flame properties

    Science.gov (United States)

    David R. Weise; Gregory S. Biging

    1996-01-01

    Abstract: The combined effects of wind velocity and percent slope on flame length and angle were measured in an open-topped, tilting wind tunnel by burning fuel beds composed of vertical birch sticks and aspen excelsior. Mean flame length ranged from 0.08 to 1.69 m; 0.25 m was the maximum observed flame length for most backing fires. Flame angle ranged from -46o to 50o...

  1. Solar wind velocity and geomagnetic moment variations

    International Nuclear Information System (INIS)

    Kalinin, Yu.D.; Rozanova, T.S.

    1982-01-01

    The mean year values of the solar wind velocity have been calculated from the mean-year values of a geomagnetic activity index am according to the Svalgard equation of regression for the pe-- riod from 1930 to 1960. For the same years the values of the geomagnetic moment M and separately of its ''inner'' (causes of which'' are inside the Earth) and ''external'' (causes of which are outside the Earth) parts have been calculated from the mean year data of 12 magnetic observatories. The proof of the presence of the 11-year variation in the moment M has been obtained. It is concluded that the 11-year variations in M result from the variations of the solar wind velocity

  2. Characteristics of Wind Velocity and Temperature Change Near an Escarpment-Shaped Road Embankment

    Directory of Open Access Journals (Sweden)

    Young-Moon Kim

    2014-01-01

    Full Text Available Artificial structures such as embankments built during the construction of highways influence the surrounding airflow. Various types of damage can occur due to changes in the wind velocity and temperature around highway embankments. However, no study has accurately measured micrometeorological changes (wind velocity and temperature due to embankments. This study conducted a wind tunnel test and field measurement to identify changes in wind velocity and temperature before and after the construction of embankments around roads. Changes in wind velocity around an embankment after its construction were found to be influenced by the surrounding wind velocity, wind angle, and the level difference and distance from the embankment. When the level difference from the embankment was large and the distance was up to 3H, the degree of wind velocity declines was found to be large. In changes in reference wind velocities around the embankment, wind velocity increases were not proportional to the rate at which wind velocities declined. The construction of the embankment influenced surrounding temperatures. The degree of temperature change was large in locations with large level differences from the embankment at daybreak and during evening hours when wind velocity changes were small.

  3. Results of verification and investigation of wind velocity field forecast. Verification of wind velocity field forecast model

    International Nuclear Information System (INIS)

    Ogawa, Takeshi; Kayano, Mitsunaga; Kikuchi, Hideo; Abe, Takeo; Saga, Kyoji

    1995-01-01

    In Environmental Radioactivity Research Institute, the verification and investigation of the wind velocity field forecast model 'EXPRESS-1' have been carried out since 1991. In fiscal year 1994, as the general analysis, the validity of weather observation data, the local features of wind field, and the validity of the positions of monitoring stations were investigated. The EXPRESS which adopted 500 m mesh so far was improved to 250 m mesh, and the heightening of forecast accuracy was examined, and the comparison with another wind velocity field forecast model 'SPEEDI' was carried out. As the results, there are the places where the correlation with other points of measurement is high and low, and it was found that for the forecast of wind velocity field, by excluding the data of the points with low correlation or installing simplified observation stations to take their data in, the forecast accuracy is improved. The outline of the investigation, the general analysis of weather observation data and the improvements of wind velocity field forecast model and forecast accuracy are reported. (K.I.)

  4. Variation of the solar wind velocity following solar flares

    International Nuclear Information System (INIS)

    Huang, Y.; Lee, Y.

    1975-01-01

    By use of the superposed epoch method, changes in the solar wind velocity following solar flares have been investigated by using the solar wind velocity data obtained by Pioneer 6 and 7 and Vela 3, 4, and 5 satellites. A significant increase of the solar wind velocity has been found on the second day following importance 3 solar flares and on the third day following importance 2 solar flares. No significant increase of the solar wind velocity has been found for limb flares. (auth)

  5. Generalized multidemensional propagation velocity equations for pool-boiling superconducting windings

    International Nuclear Information System (INIS)

    Christensen, E.H.; O'Loughlin, J.M.

    1984-09-01

    Several finite difference, finite element detailed analyses of propagation velocities in up to three dimensions in pool-boiling windings have been conducted for different electromagnetic and cryogenic environments. Likewise, a few full scale simulated winding and magnet tests have measured propagation velocities. These velocity data have been correlated in terms of winding thermophysical parameters. This analysis expresses longitudinal and transverse propagation velocities in the form of power function regression equations for a wide variety of windings and electromagnetic and thermohydraulic environments. The generalized velocity equations are considered applicable to well-ventilated, monolithic conductor windings. These design equations are used piecewise in a gross finite difference mode as functions of field to predict the rate of normal zone growth during quench conditions. A further check of the validity of these predictions is available through total predicted quench durations correlated with actual quench durations of large magnets

  6. Parameters determining maximum wind velocity in a tropical cyclone

    International Nuclear Information System (INIS)

    Choudhury, A.M.

    1984-09-01

    The spiral structure of a tropical cyclone was earlier explained by a tangential velocity distribution which varies inversely as the distance from the cyclone centre outside the circle of maximum wind speed. The case has been extended in the present paper by adding a radial velocity. It has been found that a suitable combination of radial and tangential velocities can account for the spiral structure of a cyclone. This enables parametrization of the cyclone. Finally a formula has been derived relating maximum velocity in a tropical cyclone with angular momentum, radius of maximum wind speed and the spiral angle. The shapes of the spirals have been computed for various spiral angles. (author)

  7. Characterization of wind velocities in the upstream induction zone of a wind turbine using scanning continuous-wave lidars

    DEFF Research Database (Denmark)

    Simley, Eric; Angelou, Nikolas; Mikkelsen, Torben Krogh

    2016-01-01

    As a wind turbine generates power, induced velocities, lower than the freestream velocity, will be present upstream of the turbine due to perturbation of the flow by the rotor. In this study, the upstream induction zone of a 225kW horizontal axis Vestas V27 wind turbine located at the Danish...... Technical University’s Risø campus is investigated using a scanning Light Detection and Ranging (lidar) system. Three short-range continuous-wave “WindScanner” lidars are positioned in the field around the V27 turbine allowing detection of all three components of the wind velocity vectors within...... the induction zone. The time-averaged mean wind speeds at different locations in the upstream induction zone are measured by scanning a horizontal plane at hub height and a vertical plane centered at the middle of the rotor extending roughly 1.5 rotor diameters (D) upstream of the rotor. Turbulence statistics...

  8. Relationship between velocity gradients and magnetic turbulence in the solar wind

    International Nuclear Information System (INIS)

    Garrett, H.B.

    1974-01-01

    The correlations among the time derivative of the solar-wind velocity, the magnitude of the interplanetary magnetic field (IMF), and the IMF turbulence level are examined to test the idea that interaction between two colliding solar-wind streams can generate turbulence in the solar wind and the IMF. Data obtained by Explorer 33 on the solar wind and IMF are described, and the analysis techniques are outlined. The results indicate that the IMF turbulence level, as measured by the variance, is correlated with the existence of positive velocity gradients in the solar wind. It is noted that while the variance is an increasing function of the field magnitude, it is also independently correlated with the solar-wind velocity gradient

  9. Wind-induced flow velocity effects on nutrient concentrations at Eastern Bay of Lake Taihu, China.

    Science.gov (United States)

    Jalil, Abdul; Li, Yiping; Du, Wei; Wang, Jianwei; Gao, Xiaomeng; Wang, Wencai; Acharya, Kumud

    2017-07-01

    Shallow lakes are highly sensitive to respond internal nutrient loading due to wind-induced flow velocity effects. Wind-induced flow velocity effects on nutrient suspension were investigated at a long narrow bay of large shallow Lake Taihu, the third largest freshwater lake in China. Wind-induced reverse/compensation flow and consistent flow field probabilities at vertical column of the water were measured. The probabilities between the wind field and the flow velocities provided a strong correlation at the surface (80.6%) and the bottom (65.1%) layers of water profile. Vertical flow velocity profile analysis provided the evidence of delay response time to wind field at the bottom layer of lake water. Strong wind field generated by the west (W) and west-north-west (WNW) winds produced displaced water movements in opposite directions to the prevailing flow field. An exponential correlation was observed between the current velocities of the surface and the bottom layers while considering wind speed as a control factor. A linear model was developed to correlate the wind field-induced flow velocity impacts on nutrient concentration at the surface and bottom layers. Results showed that dominant wind directions (ENE, E, and ESE) had a maximum nutrient resuspension contribution (nutrient resuspension potential) of 34.7 and 43.6% at the surface and the bottom profile layers, respectively. Total suspended solids (TSS), total nitrogen (TN), and total phosphorus (TP) average concentrations were 6.38, 1.5, and 0.03 mg/L during our field experiment at Eastern Bay of Lake Taihu. Overall, wind-induced low-to-moderate hydrodynamic disturbances contributed more in nutrient resuspension at Eastern Bay of Lake Taihu. The present study can be used to understand the linkage between wind-induced flow velocities and nutrient concentrations for shallow lakes (with uniform morphology and deep margins) water quality management and to develop further models.

  10. VisibleWind: wind profile measurements at low altitude

    Science.gov (United States)

    Wilkerson, Tom; Bradford, Bill; Marchant, Alan; Apedaile, Tom; Wright, Cordell

    2009-09-01

    VisibleWindTM is developing an inexpensive rapid response system, for accurately characterizing wind shear and small scale wind phenomena in the boundary layer and for prospecting suitable locations for wind power turbines. The ValidWind system can also collect reliable "ground truth" for other remote wind sensors. The system employs small (0.25 m dia.) lightweight balloons and a tracker consisting of an Impulse 200 XL laser rangefinder coupled to a PC for automated data recording. Experiments on balloon trajectories demonstrate that the laser detection of range (+/- 0.5 m), together with measured azimuth and altitude, is an inexpensive, convenient, and capable alternative to other wind tracking methods. The maximum detection range has been increased to 2200 meters using micro-corner-cube retroreflector tape on balloons. Low power LEDs enable nighttime tracking. To avoid large balloon gyrations about the mean trajectory, we use balloons having low ascent rates and subcritical Reynolds numbers. Trajectory points are typically recorded every 4 - 7 seconds. Atmospheric features observed under conditions of inversions or "light and variable winds" include abrupt onsets of shear at altitudes of 100-250 m, velocity changes of order 1-3 m/s within layers of 10-20 m thickness, and veering of the wind direction by 180 degrees or more as altitude increases from 300 to 500 m. We have previously reported comparisons of balloon-based wind profiles with the output of a co-located sodar. Even with the Impulse rangefinder, our system still requires a "man in the loop" to track the balloon. A future system enhancement will automate balloon tracking, so that laser returns are obtained automatically at 1 Hz. While balloon measurements of large-scale, high altitude wind profiles are well known, this novel measurement system provides high-resolution, real-time characterization of the fluctuating local wind fields at the bottom of the boundary layer where wind power turbines and other

  11. 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.)

  12. Demonstration and uncertainty analysis of synchronised scanning lidar measurements of 2-D velocity fields in a boundary-layer wind tunnel

    DEFF Research Database (Denmark)

    van Dooren, Marijn Floris; Campagnolo, Filippo; Sjöholm, Mikael

    2017-01-01

    to demonstrate the benefits of synchronised scanning lidars in such experimental surroundings for the first time. The duallidar system can provide fully synchronised trajectory scans with sampling timescales ranging from seconds to minutes. First, staring mode measurements were compared to hot-wire probe...... as wake area scans were executed to illustrate the applicability of lidar scanning to the measurement of small-scale wind flow effects. An extensive uncertainty analysis was executed to assess the accuracy of the method. The downsides of lidar with respect to the hotwire probes are the larger measurement...... probe volume, which compromises the ability to measure turbulence, and the possible loss of a small part of the measurements due to hard target beam reflection. In contrast, the benefits are the high flexibility in conducting both point measurements and area scanning and the fact that remote sensing...

  13. Instrument for measuring flow velocities

    International Nuclear Information System (INIS)

    Griffo, J.

    1977-01-01

    The design described here means to produce a 'more satisfying instrument with less cost' than comparable instruments known up to now. Instead of one single turbine rotor, two similar ones but with opposite blade inclination and sense of rotation are to be used. A cylindrical measuring body is carrying in its axis two bearing blocks whose shape is offering little flow resistance. On the shaft, supported by them, the two rotors run in opposite direction a relatively small axial distance apart. The speed of each rotor is picked up as pulse recurrence frequency by a transmitter and fed to an electronic measuring unit. Measuring errors as they are caused for single rotors by turbulent flow, profile distortion of the velocity, or viscous flow are to be eliminated by means of the contrarotating turbines and the subsequently added electronic unit, because in these cases the adulterating increase of the angular velocity of one rotor is compensated by a corresponding deceleration of the other rotor. The mean value then indicated by the electronic unit has high accurancy of measurement. (RW) [de

  14. A mixing method for traceable air velocity measurements

    International Nuclear Information System (INIS)

    Sillanpää, S; Heinonen, M

    2008-01-01

    A novel and quite simple method to establish a traceability link between air velocity and the national standards of mass and time is presented in this paper. The method is based on the humidification of flowing air before the blower of a wind tunnel with a known mass flow of water. Then air velocity can be calculated as a function of humidification water flow. The method is compared against a Pitot-tube-based velocity measurement in a wind tunnel at the MIKES. The results of these two different methods agreed well, with a maximum difference of 0.7%

  15. Velocity fluctuations in polar solar wind: a comparison between different solar cycles

    Directory of Open Access Journals (Sweden)

    B. Bavassano

    2009-02-01

    Full Text Available The polar solar wind is a fast, tenuous and steady flow that, with the exception of a relatively short phase around the Sun's activity maximum, fills the high-latitude heliosphere. The polar wind properties have been extensively investigated by Ulysses, the first spacecraft able to perform in-situ measurements in the high-latitude heliosphere. The out-of-ecliptic phases of Ulysses cover about seventeen years. This makes possible to study heliospheric properties at high latitudes in different solar cycles. In the present investigation we focus on hourly- to daily-scale fluctuations of the polar wind velocity. Though the polar wind is a quite uniform flow, fluctuations in its velocity do not appear negligible. A simple way to characterize wind velocity variations is that of performing a multi-scale statistical analysis of the wind velocity differences. Our analysis is based on the computation of velocity differences at different time lags and the evaluation of statistical quantities (mean, standard deviation, skewness, and kurtosis for the different ensembles. The results clearly show that, though differences exist in the three-dimensional structure of the heliosphere between the investigated solar cycles, the velocity fluctuations in the core of polar coronal holes exhibit essentially unchanged statistical properties.

  16. Velocity fluctuations in polar solar wind: a comparison between different solar cycles

    Directory of Open Access Journals (Sweden)

    B. Bavassano

    2009-02-01

    Full Text Available The polar solar wind is a fast, tenuous and steady flow that, with the exception of a relatively short phase around the Sun's activity maximum, fills the high-latitude heliosphere. The polar wind properties have been extensively investigated by Ulysses, the first spacecraft able to perform in-situ measurements in the high-latitude heliosphere. The out-of-ecliptic phases of Ulysses cover about seventeen years. This makes possible to study heliospheric properties at high latitudes in different solar cycles. In the present investigation we focus on hourly- to daily-scale fluctuations of the polar wind velocity. Though the polar wind is a quite uniform flow, fluctuations in its velocity do not appear negligible. A simple way to characterize wind velocity variations is that of performing a multi-scale statistical analysis of the wind velocity differences. Our analysis is based on the computation of velocity differences at different time lags and the evaluation of statistical quantities (mean, standard deviation, skewness, and kurtosis for the different ensembles. The results clearly show that, though differences exist in the three-dimensional structure of the heliosphere between the investigated solar cycles, the velocity fluctuations in the core of polar coronal holes exhibit essentially unchanged statistical properties.

  17. Measuring probe for measurement of local velocities

    International Nuclear Information System (INIS)

    Casal, V.; Arnold, G.; Kirchner, R.; Kussmaul, H.; Miller, H.

    1988-03-01

    The report describes a method for measurement of local velocities. It bases on the detection of the propagation of a temperature pulse induced into the fluid. The method can also be applied in flowing liquid metals with superimposed magnetic field; in this case common measuring principles fail application. The measuring system discussed consists of, a measuring head, a heating system, amplifiers and a PC. The latter performs process operation, data sampling, and evaluation of velocity. The measuring head itself includes a miniaturized heater (as a pulse marker) heated by the heating system in a short pulse, and a number of thermocouples (sensors) for detection of signals. The design, construction, and examination of a developed measuring device is described. (orig.) [de

  18. Wind Tunnel Measurements at LM Wind Power

    DEFF Research Database (Denmark)

    Bertagnolio, Franck

    2012-01-01

    This section presents the results obtained during the experimental campaign that was conducted in the wind tunnel at LM Wind Power in Lunderskov from August 16th to 26th, 2010. The goal of this study is to validate the so-called TNO trailing edge noise model through measurements of the boundary...... layer turbulence characteristics and the far-field noise generated by the acoustic scattering of the turbulent boundary layer vorticies as they convect past the trailing edge. This campaign was conducted with a NACA0015 airfoil section that was placed in the wind tunnel section. It is equipped with high...

  19. Artificial neural network approach to spatial estimation of wind velocity data

    International Nuclear Information System (INIS)

    Oztopal, Ahmet

    2006-01-01

    In any regional wind energy assessment, equal wind velocity or energy lines provide a common basis for meaningful interpretations that furnish essential information for proper design purposes. In order to achieve regional variation descriptions, there are methods of optimum interpolation with classical weighting functions or variogram methods in Kriging methodology. Generally, the weighting functions are logically and geometrically deduced in a deterministic manner, and hence, they are imaginary first approximations for regional variability assessments, such as wind velocity. Geometrical weighting functions are necessary for regional estimation of the regional variable at a location with no measurement, which is referred to as the pivot station from the measurements of a set of surrounding stations. In this paper, weighting factors of surrounding stations necessary for the prediction of a pivot station are presented by an artificial neural network (ANN) technique. The wind speed prediction results are compared with measured values at a pivot station. Daily wind velocity measurements in the Marmara region from 1993 to 1997 are considered for application of the ANN methodology. The model is more appropriate for winter period daily wind velocities, which are significant for energy generation in the study area. Trigonometric point cumulative semivariogram (TPCSV) approach results are compared with the ANN estimations for the same set of data by considering the correlation coefficient (R). Under and over estimation problems in objective analysis can be avoided by the ANN approach

  20. A parabolic velocity-decomposition method for wind turbines

    Science.gov (United States)

    Mittal, Anshul; Briley, W. Roger; Sreenivas, Kidambi; Taylor, Lafayette K.

    2017-02-01

    An economical parabolized Navier-Stokes approximation for steady incompressible flow is combined with a compatible wind turbine model to simulate wind turbine flows, both upstream of the turbine and in downstream wake regions. The inviscid parabolizing approximation is based on a Helmholtz decomposition of the secondary velocity vector and physical order-of-magnitude estimates, rather than an axial pressure gradient approximation. The wind turbine is modeled by distributed source-term forces incorporating time-averaged aerodynamic forces generated by a blade-element momentum turbine model. A solution algorithm is given whose dependent variables are streamwise velocity, streamwise vorticity, and pressure, with secondary velocity determined by two-dimensional scalar and vector potentials. In addition to laminar and turbulent boundary-layer test cases, solutions for a streamwise vortex-convection test problem are assessed by mesh refinement and comparison with Navier-Stokes solutions using the same grid. Computed results for a single turbine and a three-turbine array are presented using the NREL offshore 5-MW baseline wind turbine. These are also compared with an unsteady Reynolds-averaged Navier-Stokes solution computed with full rotor resolution. On balance, the agreement in turbine wake predictions for these test cases is very encouraging given the substantial differences in physical modeling fidelity and computer resources required.

  1. Effects of increasing tip velocity on wind turbine rotor design.

    Energy Technology Data Exchange (ETDEWEB)

    Resor, Brian Ray [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Maniaci, David Charles [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Berg, Jonathan Charles [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Richards, Phillip William [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-05-01

    A reduction in cost of energy from wind is anticipated when maximum allowable tip velocity is allowed to increase. Rotor torque decreases as tip velocity increases and rotor size and power rating are held constant. Reduction in rotor torque yields a lighter weight gearbox, a decrease in the turbine cost, and an increase in the capacity for the turbine to deliver cost competitive electricity. The high speed rotor incurs costs attributable to rotor aero-acoustics and system loads. The increased loads of high speed rotors drive the sizing and cost of other components in the system. Rotor, drivetrain, and tower designs at 80 m/s maximum tip velocity and 100 m/s maximum tip velocity are created to quantify these effects. Component costs, annualized energy production, and cost of energy are computed for each design to quantify the change in overall cost of energy resulting from the increase in turbine tip velocity. High fidelity physics based models rather than cost and scaling models are used to perform the work. Results provide a quantitative assessment of anticipated costs and benefits for high speed rotors. Finally, important lessons regarding full system optimization of wind turbines are documented.

  2. Analysis and forecasting of wind velocity in chetumal, quintana roo, using the single exponential smoothing method

    Energy Technology Data Exchange (ETDEWEB)

    Cadenas, E. [Facultad de Ingenieria Mecanica, Universidad Michoacana de San Nicolas de Hidalgo, Santiago Tapia No. 403, Centro (Mexico); Jaramillo, O.A.; Rivera, W. [Centro de Ivestigacion en Energia, Universidad Nacional Autonoma de Mexico, Apartado Postal 34, Temixco 62580, Morelos (Mexico)

    2010-05-15

    In this paper the analysis and forecasting of wind velocities in Chetumal, Quintana Roo, Mexico is presented. Measurements were made by the Instituto de Investigaciones Electricas (IIE) during two years, from 2004 to 2005. This location exemplifies the wind energy generation potential in the Caribbean coast of Mexico that could be employed in the hotel industry in the next decade. The wind speed and wind direction were measured at 10 m above ground level. Sensors with high accuracy and a low starting threshold were used. The wind velocity was recorded using a data acquisition system supplied by a 10 W photovoltaic panel. The wind speed values were measured with a frequency of 1 Hz and the average wind speed was recorded considering regular intervals of 10 min. First a statistical analysis of the time series was made in the first part of the paper through conventional and robust measures. Also the forecasting of the last day of measurements was made utilizing the single exponential smoothing method (SES). The results showed a very good accuracy of the data with this technique for an {alpha} value of 0.9. Finally the SES method was compared with the artificial neural network (ANN) method showing the former better results. (author)

  3. Design of a wind turbine-generator system considering the conformability to wind velocity fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Wakui, Tetsuya; Hashizume, Takumi; Outa, Eisuke

    1999-07-01

    The conformability of the rated power output of the wind turbine-generator system and of the wind turbine type to wind velocity fluctuations are investigated with a simulation model. The authors examine three types of wind turbines: the Darrieus-Savonius hybrid, the Darrieus proper and the Propeller. These systems are mainly operated at a constant tip speed ratio, which refers to a maximum power coefficient points. As a computed result of the net extracting power, the Darrieus turbine proper has little conformability to wind velocity fluctuations because of its output characteristics. As for the other turbines, large-scale systems do not always have an advantage over small-scale systems as the effect of its dynamic characteristics. Furthermore, it is confirmed that the net extracting power of the Propeller turbine, under wind direction fluctuation, is much reduced when compared with the hybrid wind turbine. Thus, the authors conclude that the appropriate rated power output of the system exists with relation to the wind turbine type for each wind condition.

  4. Wind Velocity and Position Sensor-less Operation for PMSG Wind Generator

    Science.gov (United States)

    Senjyu, Tomonobu; Tamaki, Satoshi; Urasaki, Naomitsu; Uezato, Katsumi; Funabashi, Toshihisa; Fujita, Hideki

    Electric power generation using non-conventional sources is receiving considerable attention throughout the world. Wind energy is one of the available non-conventional energy sources. Electrical power generation using wind energy is possible in two ways, viz. constant speed operation and variable speed operation using power electronic converters. Variable speed power generation is attractive, because maximum electric power can be generated at all wind velocities. However, this system requires a rotor speed sensor, for vector control purpose, which increases the cost of the system. To alleviate the need of rotor speed sensor in vector control, we propose a new sensor-less control of PMSG (Permanent Magnet Synchronous Generator) based on the flux linkage. We can estimate the rotor position using the estimated flux linkage. We use a first-order lag compensator to obtain the flux linkage. Furthermore‚we estimate wind velocity and rotation speed using a observer. The effectiveness of the proposed method is demonstrated thorough simulation results.

  5. The Dependence of the Peak Velocity of High-Speed Solar Wind Streams as Measured in the Ecliptic by ACE and the STEREO satellites on the Area and Co-latitude of Their Solar Source Coronal Holes.

    Science.gov (United States)

    Hofmeister, Stefan J; Veronig, Astrid; Temmer, Manuela; Vennerstrom, Susanne; Heber, Bernd; Vršnak, Bojan

    2018-03-01

    We study the properties of 115 coronal holes in the time range from August 2010 to March 2017, the peak velocities of the corresponding high-speed streams as measured in the ecliptic at 1 AU, and the corresponding changes of the Kp index as marker of their geoeffectiveness. We find that the peak velocities of high-speed streams depend strongly on both the areas and the co-latitudes of their solar source coronal holes with regard to the heliospheric latitude of the satellites. Therefore, the co-latitude of their source coronal hole is an important parameter for the prediction of the high-speed stream properties near the Earth. We derive the largest solar wind peak velocities normalized to the coronal hole areas for coronal holes located near the solar equator and that they linearly decrease with increasing latitudes of the coronal holes. For coronal holes located at latitudes ≳ 60°, they turn statistically to zero, indicating that the associated high-speed streams have a high chance to miss the Earth. Similarly, the Kp index per coronal hole area is highest for the coronal holes located near the solar equator and strongly decreases with increasing latitudes of the coronal holes. We interpret these results as an effect of the three-dimensional propagation of high-speed streams in the heliosphere; that is, high-speed streams arising from coronal holes near the solar equator propagate in direction toward and directly hit the Earth, whereas solar wind streams arising from coronal holes at higher solar latitudes only graze or even miss the Earth.

  6. Alignment of stress, mean wind, and vertical gradient of the velocity vector

    DEFF Research Database (Denmark)

    Berg, Jacob; Mann, Jakob; Patton, E.G.

    2012-01-01

    In many applications in the atmospheric surface layer the turbulent-viscosity hypothesis is applied, i.e. the stress vector can be described through the vertical gradient of velocity. In the atmospheric surface layer, where the Coriolis force and baroclinic effects are considered negligible......, this is supposedly a good approximation. High resolution large-eddy simulation (LES) data show that it is indeed the case. Through analysis of WindCube lidar measurements accompanied by sonic measurements we show that this is, on the other hand, rarely the case in the real atmosphere. This might indicate that large...... of atmospheric boundary layer modeling. The measurements are from the Danish wind turbine test sites at Høvsøre. With theWindCube lidar we are able to reach heights of 250 meters and hence capture the entire atmospheric surface layer both in terms of wind speed and the direction of the mean stress vector....

  7. The measurement of low air flow velocities

    NARCIS (Netherlands)

    Aghaei, A.; Mao, X.G.; Zanden, van der A.J.J.; Schaik, W.H.J.; Hendriks, N.A.

    2005-01-01

    Air flow velocity is measured with an acoustic sensor, which can be used especially for measuring low air flow velocities as well as the temperature of the air simultaneously. Two opposite transducers send a sound pulse towards each other. From the difference of the transit times, the air flow

  8. Velocity measurement of conductor using electromagnetic induction

    International Nuclear Information System (INIS)

    Kim, Gu Hwa; Kim, Ho Young; Park, Joon Po; Jeong, Hee Tae; Lee, Eui Wan

    2002-01-01

    A basic technology was investigated to measure the speed of conductor by non-contact electromagnetic method. The principle of the velocity sensor was electromagnetic induction. To design electromagnet for velocity sensor, 2D electromagnetic analysis was performed using FEM software. The sensor output was analyzed according to the parameters of velocity sensor, such as the type of magnetizing currents and the lift-off. Output of magnetic sensor was linearly depended on the conductor speed and magnetizing current. To compensate the lift-off changes during measurement of velocity, the other magnetic sensor was put at the pole of electromagnet.

  9. Peculiar velocity measurement in a clumpy universe

    Science.gov (United States)

    Habibi, Farhang; Baghram, Shant; Tavasoli, Saeed

    Aims: In this work, we address the issue of peculiar velocity measurement in a perturbed Friedmann universe using the deviations from measured luminosity distances of standard candles from background FRW universe. We want to show and quantify the statement that in intermediate redshifts (0.5 deviations from the background FRW model are not uniquely governed by peculiar velocities. Luminosity distances are modified by gravitational lensing. We also want to indicate the importance of relativistic calculations for peculiar velocity measurement at all redshifts. Methods: For this task, we discuss the relativistic correction on luminosity distance and redshift measurement and show the contribution of each of the corrections as lensing term, peculiar velocity of the source and Sachs-Wolfe effect. Then, we use the SNe Ia sample of Union 2, to investigate the relativistic effects, we consider. Results: We show that, using the conventional peculiar velocity method, that ignores the lensing effect, will result in an overestimate of the measured peculiar velocities at intermediate redshifts. Here, we quantify this effect. We show that at low redshifts the lensing effect is negligible compare to the effect of peculiar velocity. From the observational point of view, we show that the uncertainties on luminosity of the present SNe Ia data prevent us from precise measuring the peculiar velocities even at low redshifts (z < 0.2).

  10. The OPERA neutrino velocity measurement

    Energy Technology Data Exchange (ETDEWEB)

    Wonsak, Bjoern [Universitaet Hamburg (Germany)

    2012-07-01

    OPERA is a long-baseline neutrino oscillation experiment designed to find tau neutrinos appearing in a pure muon neutrino beam. Recently, a measurement of the flight time of the neutrinos between the CNGS at CERN and the OPERA detector at the LNGS has been performed. It was found that the neutrinos arrive at the detector significantly earlier in time than expected if travelling at the speed of light. In this talk, the main aspects of this measurement are presented, including timing and geodesy issues and the analysis procedure. An update concerning results with a fine structured time distribution of the beam is given, as well as latest information on some additional cross checks.

  11. Superhilac real-time velocity measurements

    International Nuclear Information System (INIS)

    Feinberg, B.; Meaney, D.; Thatcher, R.; Timossi, C.

    1987-03-01

    Phase probes have been placed in several external beam lines at the LBL heavy ion linear accelerator (SuperHILAC) to provide non-destructive velocity measurements independent of the ion being accelerated. The existing system has been improved to provide the following features: a display refresh rate better than twice per second, a sensitive pseudo-correlation technique to pick out the signal from the noise, simultaneous measurements of up to four ion velocities when more than one beam is being accelerated, and a touch-screen operator interface. These improvements allow the system to be used as a routine tuning aid and beam velocity monitor

  12. Representivity of wind measurements for design wind speed estimations

    CSIR Research Space (South Africa)

    Goliger, Adam M

    2013-07-01

    Full Text Available of instrumentation sited according to World Meteorological Organization (WMO) requirements. With the advent of automatic weather station technology several decades ago, wind measurements have become much more cost-effective. While previously wind measurements were...

  13. The Effect of Wind Velocity on the Cooling Rate of Water

    OpenAIRE

    Shrey Aryan

    2016-01-01

    The effect of wind velocity on the cooling rate of water was investigated by blowing air horizontally over the surface of water contained in a plastic water-bottle cap. The time taken for the temperature to fall to the average of the surrounding and initial temperatures was recorded at different values of wind velocity. It was observed that on increasing the wind velocity, the time taken to achieve average temperature not only decreased but also remained the same after a certain point.

  14. Ultrasonic velocity measurements in expanded liquid mercury

    International Nuclear Information System (INIS)

    Suzuki, K.; Inutake, M.; Fujiwaka, S.

    1977-10-01

    In this paper we present the first results of the sound velocity measurements in expanded liquid mercury. The measurements were made at temperatures up to 1600 0 C and pressures up to 1700 kg/cm 2 by means of an ultrasonic pulse transmission/echo technique which was newly developed for such high temperature/pressure condition. When the density is larger than 9 g/cm 3 , the observed sound velocity decreases linearly with decreasing density. At densities smaller than 9 g/cm 3 , the linear dependence on the density is no longer observed. The observed sound velocity approaches a minimum near the liquid-gas critical point (rho sub(cr) asymptotically equals 5.5 g/cm 3 ). The existing theories for sound velocity in liquid metals fail to explain the observed results. (auth.)

  15. Determination of angular rotation velocity of Dar'e wind turbine with straight blades

    International Nuclear Information System (INIS)

    Ershina, A.K.; Ershin, Sh.A.; Upnanov, T.K.

    1999-01-01

    In the report the method of angular velocity determination for wind turbine of given capacity with allowing for an average seasonal wind velocity and all geometrical and dynamical characteristics of the unit is presented. It is noted, that this wind turbine has following advantages: wind direction does not plays role due to vertical axis position of the turbine; electric generator and other equipment are arranged on the ground, that reduce construction's weight, expedite of servicing and repair; the wind turbine has high coefficient of wind energy use (ξ max =0.45)

  16. Dynamics of the standard deviations of three wind velocity components from the data of acoustic sounding

    Science.gov (United States)

    Krasnenko, N. P.; Kapegesheva, O. F.; Shamanaeva, L. G.

    2017-11-01

    Spatiotemporal dynamics of the standard deviations of three wind velocity components measured with a mini-sodar in the atmospheric boundary layer is analyzed. During the day on September 16 and at night on September 12 values of the standard deviation changed for the x- and y-components from 0.5 to 4 m/s, and for the z-component from 0.2 to 1.2 m/s. An analysis of the vertical profiles of the standard deviations of three wind velocity components for a 6-day measurement period has shown that the increase of σx and σy with altitude is well described by a power law dependence with exponent changing from 0.22 to 1.3 depending on the time of day, and σz depends linearly on the altitude. The approximation constants have been found and their errors have been estimated. The established physical regularities and the approximation constants allow the spatiotemporal dynamics of the standard deviation of three wind velocity components in the atmospheric boundary layer to be described and can be recommended for application in ABL models.

  17. The Coincidence Tracker: Electronic Equipment for a Time-of-Flight Wind-Speed Measurement System

    DEFF Research Database (Denmark)

    Fog, Christian

    1982-01-01

    The electronic part of a laser-beam measuring system for wind velocity is described. Pulses of light scattered from aerosols are treated, first in a pair of adaptive filters, then in a tracker that calculates the wind velocity on-line while applying some knowledge about the velocity to be expected...

  18. LIDAR Wind Speed Measurements of Evolving Wind Fields

    Energy Technology Data Exchange (ETDEWEB)

    Simley, E.; Pao, L. Y.

    2012-07-01

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

  19. Controlled Velocity Testing of an 8-kW Wind Turbine

    Energy Technology Data Exchange (ETDEWEB)

    Larwood, S.; Sencenbaugh, J.; Acker, B.

    2001-07-31

    This paper describes a case study of the controlled-velocity test of an 8-kW wind turbine. The turbine was developed in response to the U.S. Department of Energy's small wind turbine program. As background, the prototype development is discussed. The turbine mechanical and electrical components are described. The turbine was tested on a flatbed truck and driven down an airfield runway at constant relative wind speed. Horizontal furling was used to control over-speed. Various parameters were changed to determine their effects on furling. The testing showed that the machine had insufficient rotor offset for adequate furling. Also, a rotor resonance problem was discovered and remedied. Problems associated with taking the measurements made it difficult to determine if the truck test was a suitable method for code validation. However, qualitative observations gleaned from the testing justified the effort.

  20. Interferometric phase velocity measurements in the auroral electrojet

    International Nuclear Information System (INIS)

    Labelle, J.; Kinter, P.M.; Kelley, M.C.

    1986-01-01

    A double-probe electric field detector and two spatially separated fixed-bias Langmuir probes were flown on a Taurus-Tomahawk sounding rocket launched from Poker Flat Research Range in March 1982. Interesting wave data have been obtained from about 10 s of the downleg portion of the flight during which the rocket passed through the auroral electrojet. Here the electric field receiver and both density fluctuation (deltan/n) receivers responded to a broad band of turbulence centered at 105 km altitude and at frequencies generally below 4 kHz. Closer examination of the two deltan/n turbulent waveforms reveals that they are correlated, and from the phase difference between the two signals, the phase velocity of the waves in the rocket reference frame is inferred. The magnitude and direction of the observed phase velocity are consistent either with waves which travel at the ion sound speed (Csub(s)) or with waves which travel at the electron drift velocity. The observed phase velocity varies by about 50% over a 5 km altitude range - an effect which probably results from shear in the zonal neutral wind, although unfortunately no simultaneous neutral wind measurements exist to confirm this. (author)

  1. Measuring power output intermittency and unsteady loading in a micro wind farm model

    OpenAIRE

    Bossuyt, Juliaan; Howland, Michael; Meneveau, Charles; Meyers, Johan

    2016-01-01

    In this study porous disc models are used as a turbine model for a wind-tunnel wind farm experiment, allowing the measurement of the power output, thrust force and spatially averaged incoming velocity for every turbine. The model's capabilities for studying the unsteady turbine loading, wind farm power output intermittency and spatio temporal correlations between wind turbines are demonstrated on an aligned wind farm, consisting of 100 wind turbine models.

  2. Velocity spectrum and blade’s deformation of horizontal axis wind turbines

    Directory of Open Access Journals (Sweden)

    Sanda BUDEA

    2014-04-01

    Full Text Available The paper presents the velocity distribution calculated by numerical method in axial relative motion of a viscous and incompressible fluid into the impeller of a horizontal axis wind turbine. Simulations are made for different airflow speeds: 0.5,1, 3, 4, 5 m/s. The relative vortex on the backside of the blade to the trailing edge, and the vortices increase with the wind speed can be observed from the numerical analysis. Also the translational deformation-the deflection of the wind turbine blades for different values of the wind velocities has been established in this paper. The numerical simulations are made for the following speed values:5 m/s, 10m/s and 20 m/s. ANSYS CFD – Fluent was used both to calculate the velocities spectrum and to establish the translational blades deformations. The analyzed wind impeller has small dimensions, a diameter of 2 m and four profiled blades. For this small impeller the translational deformation increases with the wind velocity from 83 to 142 mm. For high wind velocities and large–scale wind turbine impellers, these translational deformations are about several meters, reason to /shut-down the impellers to wind velocities exceeding 25 m/s.

  3. The Effect of Wind Velocity on the Cooling Rate of Water

    Directory of Open Access Journals (Sweden)

    Shrey Aryan

    2016-01-01

    Full Text Available The effect of wind velocity on the cooling rate of water was investigated by blowing air horizontally over the surface of water contained in a plastic water-bottle cap. The time taken for the temperature to fall to the average of the surrounding and initial temperatures was recorded at different values of wind velocity. It was observed that on increasing the wind velocity, the time taken to achieve average temperature not only decreased but also remained the same after a certain point.

  4. Multi-component wind measurements of wind turbine wakes performed with three LiDARs

    Science.gov (United States)

    Iungo, G. V.; Wu, Y.-T.; Porté-Agel, F.

    2012-04-01

    Field measurements of the wake flow produced from the interaction between atmospheric boundary layer and a wind turbine are performed with three wind LiDARs. The tested wind turbine is a 2 MW Enercon E-70 located in Collonges, Switzerland. First, accuracy of mean values and frequency resolution of the wind measurements are surveyed as a function of the number of laser rays emitted for each measurement. Indeed, measurements performed with one single ray allow maximizing sampling frequency, thus characterizing wake turbulence. On the other hand, if the number of emitted rays is increased accuracy of mean wind is increased due to the longer sampling period. Subsequently, two-dimensional measurements with a single LiDAR are carried out over vertical sections of the wind turbine wake and mean wake flow is obtained by averaging 2D measurements consecutively performed. The high spatial resolution of the used LiDAR allows characterizing in details velocity defect present in the central part of the wake and its downstream recovery. Single LiDAR measurements are also performed by staring the laser beam at fixed directions for a sampling period of about ten minutes and maximizing the sampling frequency in order to characterize wake turbulence. From these tests wind fluctuation peaks are detected in the wind turbine wake at blade top-tip height for different downstream locations. The magnitude of these turbulence peaks is generally reduced by moving downstream. This increased turbulence level at blade top-tip height observed for a real wind turbine has been already detected from previous wind tunnel tests and Large Eddy simulations, thus confirming the presence of a source of dangerous fatigue loads for following wind turbines within a wind farm. Furthermore, the proper characterization of wind fluctuations through LiDAR measurements is proved by the detection of the inertial subrange from spectral analysis of these velocity signals. Finally, simultaneous measurements with two

  5. Size and velocity measurements in combustion systems

    International Nuclear Information System (INIS)

    Levy, Y.; Timnat, Y.M.

    1986-01-01

    Two-phase flow measurements for size and velocity determination in combustion systems are discussed: the pedestal technique and phase Doppler anemometry (PDA) are described in detail. The experimental apparatus for the pedestal method includes the optical laser-Doppler anemometry (LDA) package and the electronic data acquisition system. The latter comprises three channels for recording the Doppler frequency, and the pedestal amplitude as well as the validation pulse. Results of measurements performed in a dump combustor, into which kerosene droplets were injected, are presented. The principle of the PDA technique is explained and validation experiments, using latex particles, are reported. Finally the two methods are compared

  6. The Dependence of the Peak Velocity of High-Speed Solar Wind Streams as Measured in the Ecliptic by ACE and the STEREO satellites on the Area and Co-Latitude of their Solar Source Coronal Holes

    DEFF Research Database (Denmark)

    Hofmeister, Stefan J.; Veronig, Astrid; Temmer, Manuela

    2018-01-01

    We study the properties of 115 coronal holes in the time‐range from 2010/08 to 2017/03, the peak velocities of the corresponding high‐speed streams as measured in the ecliptic at 1AU, and the corresponding changes of the Kp index as marker of their geo‐effectiveness. We find that the peak velocit...

  7. Solar wind velocity and temperature in the outer heliosphere

    Science.gov (United States)

    Gazis, P. R.; Barnes, A.; Mihalov, J. D.; Lazarus, A. J.

    1994-01-01

    At the end of 1992, the Pioneer 10, Pioneer 11, and Voyager 2 spacecraft were at heliocentric distances of 56.0, 37.3, and 39.0 AU and heliographic latitudes of 3.3 deg N, 17.4 deg N, and 8.6 deg S, respectively. Pioneer 11 and Voyager 2 are at similar celestial longitudes, while Pioneer 10 is on the opposite side of the Sun. All three spacecraft have working plasma analyzers, so intercomparison of data from these spacecraft provides important information about the global character of the solar wind in the outer heliosphere. The averaged solar wind speed continued to exhibit its well-known variation with solar cycle: Even at heliocentric distances greater than 50 AU, the average speed is highest during the declining phase of the solar cycle and lowest near solar minimum. There was a strong latitudinal gradient in solar wind speed between 3 deg and 17 deg N during the last solar minimum, but this gradient has since disappeared. The solar wind temperature declined with increasing heliocentric distance out to a heliocentric distance of at least 20 AU; this decline appeared to continue at larger heliocentric distances, but temperatures in the outer heliosphere were suprisingly high. While Pioneer 10 and Voyager 2 observed comparable solar wind temperatures, the temperature at Pioneer 11 was significantly higher, which suggests the existence of a large-scale variation of temperature with heliographic longitude. There was also some suggestion that solar wind temperatures were higher near solar minimum.

  8. High resolution climatological wind measurements for wind energy applications

    Energy Technology Data Exchange (ETDEWEB)

    Bergstroem, H. [Uppsala Univ. (Sweden). Dept. of Meteorology

    1996-12-01

    Measurements with a combined cup anemometer/wind vane instrument, developed at the Department of Meteorology in Uppsala, is presented. The instrument has a frequency response of about 1 Hz, making it suitable not only for mean wind measurements, but also for studies of atmospheric turbulence. It is robust enough to be used for climatological purposes. Comparisons with data from a hot-film anemometer show good agreement, both as regards standard deviations and the spectral decomposition of the turbulent wind signal. The cup anemometer/wind vane instrument is currently used at three sites within the Swedish wind energy research programme. These measurements are shortly described, and a few examples of the results are given. 1 ref, 10 figs

  9. Validation of Sodar Measurements for Wind Power

    DEFF Research Database (Denmark)

    Hansen, Kurt Schaldemose

    2006-01-01

    the project and a new remote power system has been designed. A direct comparison between SODAR and cup measurements revealed a limitation for the SODAR measurements during different weather conditions, especially since the SODAR was not able to measure wind speeds above 15 m/s due to an increasing back-ground......A ground-based SODAR has been tested for 1½ years together with a traditional measurement set-up consisting of cups and vanes for measuring wind data for wind power assessment at a remote location. Many problems associated to the operation of a remote located SODAR have been solved during...... noise. Instead, using the SODAR as a profiler to establish representative wind speed profiles was successful. These wind speed profiles are combined with low height reference measurements to establish reliable hub height wind speed distributions. Representative wind speed profiles can be establish...

  10. Diurnal Dynamics of Standard Deviations of Three Wind Velocity Components in the Atmospheric Boundary Layer

    Science.gov (United States)

    Shamanaeva, L. G.; Krasnenko, N. P.; Kapegesheva, O. F.

    2018-04-01

    Diurnal dynamics of the standard deviation (SD) of three wind velocity components measured with a minisodar in the atmospheric boundary layer is analyzed. Statistical analysis of measurement data demonstrates that the SDs for x- and y-components σx and σy lie in the range from 0.2 to 4 m/s, and σz = 0.1-1.2 m/s. The increase of σx and σy with the altitude is described sufficiently well by a power law with exponent changing from 0.22 to 1.3 depending on time of day, and σz increases by a linear law. Approximation constants are determined and errors of their application are estimated. It is found that the maximal diurnal spread of SD values is 56% for σx and σy and 94% for σz. The established physical laws and the obtained approximation constants allow the diurnal dynamics of the SDs for three wind velocity components in the atmospheric boundary layer to be determined and can be recommended for application in models of the atmospheric boundary layer.

  11. Acoustic methods for measuring bullet velocity

    OpenAIRE

    Courtney, Michael

    2008-01-01

    This article describes two acoustic methods to measure bullet velocity with an accuracy of 1% or better. In one method, a microphone is placed within 0.1 m of the gun muzzle and a bullet is fired at a steel target 45 m away. The bullet's flight time is the recorded time between the muzzle blast and sound of hitting the target minus the time for the sound to return from the target to the microphone. In the other method, the microphone is placed equidistant from both the gun muzzle and the stee...

  12. Optimizing Lidar Scanning Strategies for Wind Energy Measurements (Invited)

    Science.gov (United States)

    Newman, J. F.; Bonin, T. A.; Klein, P.; Wharton, S.; Chilson, P. B.

    2013-12-01

    Environmental concerns and rising fossil fuel prices have prompted rapid development in the renewable energy sector. Wind energy, in particular, has become increasingly popular in the United States. However, the intermittency of available wind energy makes it difficult to integrate wind energy into the power grid. Thus, the expansion and successful implementation of wind energy requires accurate wind resource assessments and wind power forecasts. The actual power produced by a turbine is affected by the wind speeds and turbulence levels experienced across the turbine rotor disk. Because of the range of measurement heights required for wind power estimation, remote sensing devices (e.g., lidar) are ideally suited for these purposes. However, the volume averaging inherent in remote sensing technology produces turbulence estimates that are different from those estimated by a sonic anemometer mounted on a standard meteorological tower. In addition, most lidars intended for wind energy purposes utilize a standard Doppler beam-swinging or Velocity-Azimuth Display technique to estimate the three-dimensional wind vector. These scanning strategies are ideal for measuring mean wind speeds but are likely inadequate for measuring turbulence. In order to examine the impact of different lidar scanning strategies on turbulence measurements, a WindCube lidar, a scanning Halo lidar, and a scanning Galion lidar were deployed at the Southern Great Plains Atmospheric Radiation Measurement (ARM) site in Summer 2013. Existing instrumentation at the ARM site, including a 60-m meteorological tower and an additional scanning Halo lidar, were used in conjunction with the deployed lidars to evaluate several user-defined scanning strategies. For part of the experiment, all three scanning lidars were pointed at approximately the same point in space and a tri-Doppler analysis was completed to calculate the three-dimensional wind vector every 1 second. In another part of the experiment, one of

  13. Solar wind velocity and daily variation of cosmic rays

    International Nuclear Information System (INIS)

    Ahluwalia, H.S.; Riker, J.F.

    1985-01-01

    Recently parameters applicable to the solar wind and the interplanetary magnetic field (IMF) have become much better defined. Superior quality of data bases that are now available, particularly for the post-1971 period, make it possible to believe the long-term trends in the data. These data are correlated with the secular changes observed in the diurnal variation parameters obtained from neutron monitor data at Deep River and underground muon telescope data at Embudo (30 MEW) and Socorro (82 MWE). The annual mean amplitudes appear to have large values during the epochs of high speed solar wind streams. Results are discussed

  14. Effects of Wind Velocity Driven by Alfven Waves on the Line Profiles for 32 CYG

    Directory of Open Access Journals (Sweden)

    Kyung-Mee Kim

    1996-06-01

    Full Text Available We calculate the theoretical line profiles for 32 Cyg in order to investigate the influence of various velocity fields. Line profiles are calculated with wind accelerations driven by Alfven waves and described by velocity parameters. The results for Alfvenic wave model show weakened line profiles. For the orbital phases ¥÷=0.78 and ¥÷=0.06 the Alfvenic models show strong absorption part due to very low densities at the surface of the supergiant. Hence, we conclude the velocity gradient of the wind near the supergiant could influence on the theoretical line formation.

  15. Estimation of the variations of ventilation rate and indoor radon concentration using the observed wind velocity and indoor-outdoor temperature difference

    International Nuclear Information System (INIS)

    Nagano, Katsuhiro; Inose, Yuichi; Kojima, Hiroshi

    2006-01-01

    The indoor radon concentration in the building depends on the ventilation rate. Measurement results of indoor-outdoor pressure difference showed the ventilation rate correlated closely with the indoor-outdoor pressure difference. The observation results showed that one of factor of indoor-outdoor pressure difference was the wind velocity. When the wind velocity is small, the ventilation rate is affected by the indoor-outdoor temperature difference and the effect depends on the wind velocity. The temporal variation of indoor radon concentration was predicted by the time depending indoor radon balance model and the ventilation rate estimated from the wind velocity and the indoor-outdoor temperature difference. The temporal variations of predicted radon concentration gave good agreement with the experimental values. The measurement method, indoor radon concentration and ventilation rate, factors of temporal variation of ventilation rate, and prediction of indoor radon concentration are reported. (S.Y.)

  16. Measurements of ammonia concentrations, fluxes and dry deposition velocities to a spruce forest 1991-1995

    DEFF Research Database (Denmark)

    Andersen, H.V.; Hovmand, M.F.; Hummelshøj, P.

    1999-01-01

    The dry deposition velocities and fluxes of ammonia have been estimated from measurements of the vertical gradient of ammonia and micrometeorology above a spruce forest in western Jutland, Denmark. Measurements have been made in seven periods, each lasting about one week and covering all seasons...... measuring period characterized by easterly winds with dry conditions and high ammonia concentrations, and the emissions might relate to evaporation from ammonia saturated surfaces or emission from mineralization in the forest soil. In general, relatively high net deposition velocities were observed during...... at conditions with easterly winds, the air have passed central Jutland with large emission areas. Some of the relatively low deposition velocities or emissions were observed during conditions with low ammonia concentration and westerly winds. These observations might relate to a compensation point of the forest...

  17. Using Particle Image Velocimetry to Measure the Wind in a Winnowing Chamber

    OpenAIRE

    Matsui, Masami; Inoue, Eiji; Kuwano, Tomoko; Mori, Ken; Furuno, Yuko

    2003-01-01

    The array of vectors for the winnowing wind in the threshing unit was investigated uding PIV in order to improve the winnowing accuracy. It is difficult to measure wind velocities at many points simultaneously using the anemometer. However, visualization of the winnowing wind was possible using the tracer and laser beam. Futhermore, The PIV method made it possible to measure an array of vectors for the winnowing wind. The results produced by PIV concurred with the results of conventional meth...

  18. Effect of operating methods of wind turbine generator system on net power extraction under wind velocity fluctuations in fields

    Energy Technology Data Exchange (ETDEWEB)

    Wakui, Tetsuya; Yamaguchi, Kazuya; Hashizume, Takumi [Waseda Univ., Advanced Research Inst. for Science and Engineering, Tokyo (Japan); Outa, Eisuke [Waseda Univ., Mechanical Engineering Dept., Tokyo (Japan); Tanzawa, Yoshiaki [Nippon Inst. of Technology, Mechanical Engineering Dept., Saitama (Japan)

    1999-01-01

    The effect of how a wind turbine generator system is operated is discussed from the viewpoint of net power extraction with wind velocity fluctuation in relation to the scale and the dynamic behaviour of the system. On a wind turbine generator system consisting of a Darrieus-Savonius hybrid wind turbine, a load generator and a battery, we took up two operating methods: constant tip speed ratio operation for a stand-alone system (Scheme 1) and synchronous operation by connecting a grid (Scheme 2). With our simulation model, using the result of the net extracting power, we clarified that Scheme 1 is more effective than Scheme 2 for small-scale systems. Furthermore, in Scheme 1, the appropriate rated power output of the system under each wind condition can be confirmed. (Author)

  19. Remote Sensing Data in Wind Velocity Field Modelling: a Case Study from the Sudetes (SW Poland)

    Science.gov (United States)

    Jancewicz, Kacper

    2014-06-01

    The phenomena of wind-field deformation above complex (mountainous) terrain is a popular subject of research related to numerical modelling using GIS techniques. This type of modelling requires, as input data, information on terrain roughness and a digital terrain/elevation model. This information may be provided by remote sensing data. Consequently, its accuracy and spatial resolution may affect the results of modelling. This paper represents an attempt to conduct wind-field modelling in the area of the Śnieżnik Massif (Eastern Sudetes). The modelling process was conducted in WindStation 2.0.10 software (using the computable fluid dynamics solver Canyon). Two different elevation models were used: the Global Land Survey Digital Elevation Model (GLS DEM) and Digital Terrain Elevation Data (DTED) Level 2. The terrain roughness raster was generated on the basis of Corine Land Cover 2006 (CLC 2006) data. The output data were post-processed in ArcInfo 9.3.1 software to achieve a high-quality cartographic presentation. Experimental modelling was conducted for situations from 26 November 2011, 25 May 2012, and 26 May 2012, based on a limited number of field measurements and using parameters of the atmosphere boundary layer derived from the aerological surveys provided by the closest meteorological stations. The model was run in a 100-m and 250-m spatial resolution. In order to verify the model's performance, leave-one-out cross-validation was used. The calculated indices allowed for a comparison with results of former studies pertaining to WindStation's performance. The experiment demonstrated very subtle differences between results in using DTED or GLS DEM elevation data. Additionally, CLC 2006 roughness data provided more noticeable improvements in the model's performance, but only in the resolution corresponding to the original roughness data. The best input data configuration resulted in the following mean values of error measure: root mean squared error of velocity

  20. High-velocity winds from a dwarf nova during outburst

    Science.gov (United States)

    Cordova, F. A.; Mason, K. O.

    1982-01-01

    An ultraviolet spectrum of the dwarf nova TW Vir during an optical outburst shows shortward-shifted absorption features with edge velocities as high as 4800 km/s, about the escape velocity of a white dwarf. A comparison of this spectrum with the UV spectra of other cataclysmic variables suggests that mass loss is evident only for systems with relatively high luminosities (more than about 10 solar luminosities) and low inclination angles with respect to the observer's line of sight. The mass loss rate for cataclysmic variables is of order 10 to the -11th solar mass per yr; this is from 0.01 to 0.001 of the mass accretion rate onto the compact star in the binary. The mass loss may occur by a mechanism similar to that invoked for early-type stars, i.e., radiation absorbed in the lines accelerates the accreting gas to the high velocities observed.

  1. 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

  2. High resolution wind measurements for offshore wind energy development

    Science.gov (United States)

    Nghiem, Son Van (Inventor); Neumann, Gregory (Inventor)

    2013-01-01

    A method, apparatus, system, article of manufacture, and computer readable storage medium provide the ability to measure wind. Data at a first resolution (i.e., low resolution data) is collected by a satellite scatterometer. Thin slices of the data are determined. A collocation of the data slices are determined at each grid cell center to obtain ensembles of collocated data slices. Each ensemble of collocated data slices is decomposed into a mean part and a fluctuating part. The data is reconstructed at a second resolution from the mean part and a residue of the fluctuating part. A wind measurement is determined from the data at the second resolution using a wind model function. A description of the wind measurement is output.

  3. Estimation of power in low velocity vertical axis wind turbine

    Science.gov (United States)

    Sampath, S. S.; Shetty, Sawan; Chithirai Pon Selvan, M.

    2015-06-01

    The present work involves in the construction of a vertical axis wind turbine and the determination of power. Various different types of turbine blades are considered and the optimum blade is selected. Mechanical components of the entire setup are built to obtain maximum rotation per minute. The mechanical energy is converted into the electrical energy by coupling coaxially between the shaft and the generator. This setup produces sufficient power for consumption of household purposes which is economic and easily available.

  4. 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

  5. Wind measurement via direct detection lidar

    Science.gov (United States)

    Afek, I.; Sela, N.; Narkiss, N.; Shamai, G.; Tsadka, S.

    2013-10-01

    Wind sensing Lidar is considered a promising technology for high quality wind measurements required for various applications such as hub height wind resource assessment, power curve measurements and advanced, real time, forward looking turbine control. Until recently, the only available Lidar technology was based on coherent Doppler shift detection, whose market acceptance has been slow primarily due to its exuberant price. Direct detection Lidar technology provides an alternative to remote sensing of wind by incorporating high precision measurement, a robust design and an affordable price tag.

  6. Characterization of wind velocities in the wake of a full scale wind turbine using three ground-based synchronized WindScanners

    DEFF Research Database (Denmark)

    Yazicioglu, Hasan; Angelou, Nikolas; Mikkelsen, Torben Krogh

    2016-01-01

    The wind energy community is in need of detailed full-field measurements in the wake of wind turbines. Here, three dimensional(3D) wind vector field measurements obtained in the near-wake region behind a full-scale test turbine are presented. Specifically, the wake of a NEG Nordtank turbine...

  7. Crack velocity measurement by induced electromagnetic radiation

    International Nuclear Information System (INIS)

    Frid, V.; Rabinovitch, A.; Bahat, D.

    2006-01-01

    Our model of electromagnetic radiation (EMR) emanated from fracture implies that EMR amplitude is proportional to crack velocity. Soda lime glass samples were tested under uniaxial tension. Comparison of crack velocity observed by Wallner line analysis and the peak amplitude of EMR signals registered during the test, showed very good correlation, validating this proportionality

  8. Crack velocity measurement by induced electromagnetic radiation

    Energy Technology Data Exchange (ETDEWEB)

    Frid, V. [Deichmann Rock Mechanics Laboratory of the Negev, Geological and Environmental Sciences Department, Ben Gurion University of the Negev, Beer Sheva (Israel)]. E-mail: vfrid@bgu.ac.il; Rabinovitch, A. [Deichmann Rock Mechanics Laboratory of the Negev, Physics Department, Ben Gurion University of the Negev, Beer Sheva (Israel); Bahat, D. [Deichmann Rock Mechanics Laboratory of the Negev, Geological and Environmental Sciences Department, Ben Gurion University of the Negev, Beer Sheva (Israel)

    2006-07-31

    Our model of electromagnetic radiation (EMR) emanated from fracture implies that EMR amplitude is proportional to crack velocity. Soda lime glass samples were tested under uniaxial tension. Comparison of crack velocity observed by Wallner line analysis and the peak amplitude of EMR signals registered during the test, showed very good correlation, validating this proportionality.

  9. Analysis of photosynthate translocation velocity and measurement of weighted average velocity in transporting pathway of crops

    International Nuclear Information System (INIS)

    Ge Cailin; Luo Shishi; Gong Jian; Zhang Hao; Ma Fei

    1996-08-01

    The translocation profile pattern of 14 C-photosynthate along the transporting pathway in crops were monitored by pulse-labelling a mature leaf with 14 CO 2 . The progressive spreading of translocation profile pattern along the sheath or stem indicates that the translocation of photosynthate along the sheath or stem proceed with a range of velocities rather than with just a single velocity. The method for measuring the weighted average velocity of photosynthate translocation along the sheath or stem was established in living crops. The weighted average velocity and the maximum velocity of photosynthate translocation along the sheath in rice and maize were measured actually. (4 figs., 3 tabs.)

  10. VLTI-AMBER Velocity-Resolved Aperture-Synthesis Imaging of Eta Carinae with a Spectral Resolution of 12 000: Studies of the Primary Star Wind and Innermost Wind-Wind Collision Zone

    Science.gov (United States)

    Weigelt, G.; Hofmann, K.-H.; Schertl, D.; Clementel, N.; Corcoran, M. F.; Damineli, A.; de Wit, W.-J.; Grellmann, R.; Groh, J.; Guieu, S.; hide

    2016-01-01

    The mass loss from massive stars is not understood well. Eta Carinae is a unique object for studying the massive stellar wind during the luminous blue variable phase. It is also an eccentric binary with a period of 5.54 yr. The nature of both stars is uncertain, although we know from X-ray studies that there is a wind-wind collision whose properties change with orbital phase. Aims. We want to investigate the structure and kinematics of Car's primary star wind and wind-wind collision zone with a high spatial resolution of approx.6 mas (approx.14 au) and high spectral resolution of R = 12 000. Methods. Observations of Car were carried out with the ESO Very Large Telescope Interferometer (VLTI) and the AMBER instrument between approximately five and seven months before the August 2014 periastron passage. Velocity-resolved aperture-synthesis images were reconstructed from the spectrally dispersed interferograms. Interferometric studies can provide information on the binary orbit, the primary wind, and the wind collision. Results. We present velocity-resolved aperture-synthesis images reconstructed in more than 100 di erent spectral channels distributed across the Br(gamma) 2.166 micron emission line. The intensity distribution of the images strongly depends on wavelength. At wavelengths corresponding to radial velocities of approximately -140 to -376 km/s measured relative to line center, the intensity distribution has a fan-shaped structure. At the velocity of -277 km/s, the position angle of the symmetry axis of the fan is 126. The fan-shaped structure extends approximately 8.0 mas (approx.18:8 au) to the southeast and 5.8 mas (approx.13:6 au) to the northwest, measured along the symmetry axis at the 16% intensity contour. The shape of the intensity distributions suggests that the obtained images are the first direct images of the innermost wind-wind collision zone. Therefore, the observations provide velocity-dependent image structures that can be used to test three

  11. The Dependence of the Peak Velocity of High-Speed Solar Wind Streams as Measured in the Ecliptic by ACE and the STEREO satellites on the Area and Co-Latitude of their Solar Source Coronal Holes

    DEFF Research Database (Denmark)

    Hofmeister, Stefan J.; Veronig, Astrid; Temmer, Manuela

    2018-01-01

    We study the properties of 115 coronal holes in the time‐range from 2010/08 to 2017/03, the peak velocities of the corresponding high‐speed streams as measured in the ecliptic at 1AU, and the corresponding changes of the Kp index as marker of their geo‐effectiveness. We find that the peak...... statistically to zero, indicating that the associated high‐speed streams have a high chance to miss the Earth. Similar, the Kp index per coronal hole area is highest for the coronal holes located near the solar equator and strongly decreases with increasing latitudes of the coronal holes. We interpret...

  12. On a relation of geomagnetic activity, solar wind velocity and irregularity of daily rotation of the Earth

    International Nuclear Information System (INIS)

    Kalinin, Yu.D.; Kiselev, V.M.

    1980-01-01

    A possibility of the presence of statistic relation between the changes of the Earth rotation regime and the mean velocity of solar wind is discussed. The ratio between the solar wind velocity observed and planetary index of geomagnetic activity am is used to determine the annual average values of solar wind velocity beyond the twentieth cycle of solar activity. The restored changes of solar wind velocity are compared with solar conditioned variations of the Earth day duration and it is shown that the correspondence takes place only at frequencies lower the frequency of 11-year cycle [ru

  13. Plasma flow velocity measurements using a modulated Michelson interferometer

    International Nuclear Information System (INIS)

    Howard, J.

    1997-01-01

    This paper discusses the possibility of flow velocity reconstruction using passive spectroscopic techniques. We report some preliminary measurements of the toroidal flow velocity of hydrogen atoms in the RTP tokamak using a phase modulated Michelson interferometer. (orig.)

  14. Mobile measurement system for wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Kildemoes Moeller, T.

    1997-06-01

    The aim of this project `Udviklingsafproevning af smaa moellevinger` has been to develop a mobile measurement system for wind turbines. The following report describes the measurement system. The project has been financed by the Danish Ministry of Energy. (au)

  15. Validation of Sodar Measurements for Wind Power

    OpenAIRE

    Hansen, Kurt Schaldemose

    2006-01-01

    A ground-based SODAR has been tested for 1½ years together with a traditional measurement set-up consisting of cups and vanes for measuring wind data for wind power assessment at a remote location. Many problems associated to the operation of a remote located SODAR have been solved during the project and a new remote power system has been designed. A direct comparison between SODAR and cup measurements revealed a limitation for the SODAR measurements during different weather conditions, espec...

  16. How well can we measure the vertical wind speed? Implications for fluxes of energy and mass

    Science.gov (United States)

    John Kochendorfer; Tilden P. Meyers; John Frank; William J. Massman; Mark W. Heuer

    2012-01-01

    Sonic anemometers are capable of measuring the wind speed in all three dimensions at high frequencies (10­50 Hz), and are relied upon to estimate eddy-covariance-based fluxes of mass and energy over a wide variety of surfaces and ecosystems. In this study, wind-velocity measurement errors from a three-dimensional sonic anemometer with a nonorthogonal transducer...

  17. Wind turbine wake measurement in complex terrain

    DEFF Research Database (Denmark)

    Hansen, Kurt Schaldemose; Larsen, Gunner Chr.; Menke, Robert

    2016-01-01

    SCADA data from a wind farm and high frequency time series measurements obtained with remote scanning systems have been analysed with focus on identification of wind turbine wake properties in complex terrain. The analysis indicates that within the flow regime characterized by medium to large dow...

  18. A New Filtering Algorithm Utilizing Radial Velocity Measurement

    Institute of Scientific and Technical Information of China (English)

    LIU Yan-feng; DU Zi-cheng; PAN Quan

    2005-01-01

    Pulse Doppler radar measurements consist of range, azimuth, elevation and radial velocity. Most of the radar tracking algorithms in engineering only utilize position measurement. The extended Kalman filter with radial velocity measureneut is presented, then a new filtering algorithm utilizing radial velocity measurement is proposed to improve tracking results and the theoretical analysis is also given. Simulation results of the new algorithm, converted measurement Kalman filter, extended Kalman filter are compared. The effectiveness of the new algorithm is verified by simulation results.

  19. Assessment of wind turbine load measurement instrumentation

    Energy Technology Data Exchange (ETDEWEB)

    Morfiadakis, E; Papadopoulos, K [CRES (Greece); Borg, N van der [ECN, Petten (Netherlands); Petersen, S M [Risoe, Roskilde (Denmark); Seifert, H [DEWI, Wilhelmshaven (Germany)

    1999-03-01

    In the framework of Sub-Task3 `Wind turbine load measurement instrumentation` of EU-project `European Wind Turbine Testing Procedure Development`, the load measurement techniques have been assessed by laboratory, full scale and numerical tests. The existing methods have been reviewed with emphasis on the strain gage application techniques on composite materials and recommendations are provided for the optimisation of load measurement techniques. (au) EU. 14 refs.

  20. Airflow over Barchan dunes: field measurements, mathematical modelling and wind tunnel testing

    OpenAIRE

    Wiggs, G. F. S.

    1992-01-01

    There are few empirical measurements of velocity, shear velocity, sand transport, morphological change on the windward slopes of dunes.This thesis compares field measurements on a barchan dune in Oman with calculations using a mathematical model (FLOWSTAR) and measurements in a wind tunnel. All three techniques demonstrate similar patterns of velocity, confirming the acceleration of flow up the windward slope, deceleration between the crest and brink and significant flow decele...

  1. Measuring tropospheric wind with microwave sounders

    Science.gov (United States)

    Lambrigtsen, B.; Su, H.; Turk, J.; Hristova-Veleva, S. M.; Dang, V. T.

    2017-12-01

    In its 2007 "Decadal Survey" of earth science missions for NASA the U.S. National Research Council recommended that a Doppler wind lidar be developed for a three-dimensional tropospheric winds mission ("3D-Winds"). The technology required for such a mission has not yet been developed, and it is expected that the next Decadal Survey, planned to be released by the end of 2017, will put additional emphasis on the still pressing need for wind measurements from space. The first Decadal Survey also called for a geostationary microwave sounder (GMS) on a Precipitation and All-weather Temperature and Humidity (PATH) mission, which could be used to measure wind from space. Such a sounder, the Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR), has been developed at the Jet Propulsion Laboratory (JPL). The PATH mission has not yet been funded by NASA, but a low-cost subset of PATH, GeoStorm has been proposed as a hosted payload on a commercial communications satellite. Both PATH and GeoStorm would obtain frequent (every 15 minutes of better) measurements of tropospheric water vapor profiles, and they can be used to derive atmospheric motion vector (AMV) wind profiles, even in the presence of clouds. Measurement of wind is particularly important in the tropics, where the atmosphere is largely not in thermal balance and wind estimates cannot generally be derived from temperature and pressure fields. We report on simulation studies of AMV wind vectors derived from a GMS and from a cluster of low-earth-orbiting (LEO) small satellites (e.g., CubeSats). The results of two separate simulation studies are very encouraging and show that a ±2 m/s wind speed precision is attainable, which would satisfy WMO requirements. A GMS observing system in particular, which can be implemented now, would enable significant progress in the study of atmospheric dynamics. Copyright 2017 California Institute of Technology. Government sponsorship acknowledged

  2. A new method for measurement of granular velocities

    International Nuclear Information System (INIS)

    Nyborg Andersen, B.

    1984-01-01

    A new, supplementary method to measure granular velocities is presented. The method utilizes the Doppler shift caused by the line of sight component of the solar rotation to cause a wavelength shift through spectral lines as function of heliocentric angle. By measuring the center-to-limb variation of the granular intensity fluctations at different wavelength positions in the lines, the velocities are found. To do this, assumptions regarding the geometrical structure of the velocity and intensity fields have to be made. Preliminary application of the method results in a steep velocity gradient suggesting zero velocity at a hight of 200 km above tau 500 = 1. Possible causes are discussed

  3. Canopy wake measurements using multiple scanning wind LiDARs

    Science.gov (United States)

    Markfort, C. D.; Carbajo Fuertes, F.; Iungo, V.; Stefan, H. G.; Porte-Agel, F.

    2014-12-01

    Canopy wakes have been shown, in controlled wind tunnel experiments, to significantly affect the fluxes of momentum, heat and other scalars at the land and water surface over distances of ˜O(1 km), see Markfort et al. (EFM, 2013). However, there are currently no measurements of the velocity field downwind of a full-scale forest canopy. Point-based anemometer measurements of wake turbulence provide limited insight into the extent and details of the wake structure, whereas scanning Doppler wind LiDARs can provide information on how the wake evolves in space and varies over time. For the first time, we present measurements of the velocity field in the wake of a tall patch of forest canopy. The patch consists of two uniform rows of 40-meter tall deciduous, plane trees, which border either side of the Allée de Dorigny, near the EPFL campus. The canopy is approximately 250 m long, and it is approximately 40 m wide, along the direction of the wind. A challenge faced while making field measurements is that the wind rarely intersects a canopy normal to the edge. The resulting wake flow may be deflected relative to the mean inflow. Using multiple LiDARs, we measure the evolution of the wake due to an oblique wind blowing over the canopy. One LiDAR is positioned directly downwind of the canopy to measure the flow along the mean wind direction and the other is positioned near the canopy to evaluate the transversal component of the wind and how it varies with downwind distance from the canopy. Preliminary results show that the open trunk space near the base of the canopy results in a surface jet that can be detected just downwind of the canopy and farther downwind dissipates as it mixes with the wake flow above. A time-varying recirculation zone can be detected by the periodic reversal of the velocity near the surface, downwind of the canopy. The implications of canopy wakes for measurement and modeling of surface fluxes will be discussed.

  4. Results from a three-month intercomparison of boundary-layer wind profiler and sodar wind measurements at Lindenberg, Germany

    Energy Technology Data Exchange (ETDEWEB)

    Beyrich, F.; Goersdorf, U.; Neisser, J.; Steinhagen, H.; Weisensee, U. [Deutscher Wetterdienst, Lindenberg (Germany). Meteorologisches Observatorium

    1998-10-01

    Intercomparison experiments with a wind profiler and a Doppler sodar have been performed at the meteorological observatory Lindenberg of the German weather service in summer, 1994, and in autumn, 1995, over a total period of about three months. The paper presents selected results of the wind measurements performed with the two systems. Sodar and wind profiler are shown to complement each other quite well. Therefore, a combination of both is a promising tool for continuous, high-resolution measurements of the wind profile. A problem to be solved is the construction of composite wind profiles when the measurements with the two systems disagree in the height range of overlapping. Measurements of the vertical velocity are difficult to assess due to their small absolute values. Long-term averages of the vertical velocity show slightly negative values, especially for the wind profiler. However, similar signatures have been found in the vertical velocity time series during frontal passages or during well-developed convection. (orig.) 7 refs.

  5. Measuring Velocity and Acceleration Using Doppler Shift of a ...

    Indian Academy of Sciences (India)

    to be used to measure its velocity and acceleration. We also apply this method, as an example here, to spectral lines of the blue-shifted jet in micro-quasar SS433 and discuss the intricacies of these measurements. Key words. Doppler effect—measuring velocity and acceleration of the source— jet in SS433. 1. Introduction.

  6. Dynamic aeroelastic stability of vertical-axis wind turbines under constant wind velocity

    Science.gov (United States)

    Nitzsche, Fred

    1994-05-01

    The flutter problem associated with the blades of a class of vertical-axis wind turbines called Darrieus is studied in detail. The spinning blade is supposed to be initially curved in a particular shape characterized by a state of pure tension at the blade cross section. From this equilibrium position a three-dimensional linear perturbation pattern is superimposed to determine the dynamic aeroelastic stability of the blade in the presence of free wind speed by means of the Floquet-Lyapunov theory for periodic systems.

  7. Online wind turbine measurement laboratory

    DEFF Research Database (Denmark)

    Hansen, K.S.; Helgesen Pedersen, K.O.; Schmidt Paulsen, U.

    2006-01-01

    conditions, 3) electrical quantities and 4) mechanical loads in terms of strain gauge signals. The data acquisition system has been designed and implemented by Risø together with students and teachers from DTU. It is based on LabVIEW© combined with a MySQL database for data management. The system enables...... calculations and extreme loads estimation in basic wind turbine courses. Power quality analysis is carried out based on high speed sampled, three-phase voltage and current signals. The wide spectrum of sensors enables a detailed study of the correlation between meteorological, mechanical and electrical...

  8. Measurement of vortex velocities over a wide range of vortex age, downstream distance and free stream velocity

    Science.gov (United States)

    Rorke, J. B.; Moffett, R. C.

    1977-01-01

    A wind tunnel test was conducted to obtain vortex velocity signatures over a wide parameter range encompassing the data conditions of several previous researchers while maintaining a common instrumentation and test facility. The generating wing panel was configured with both a revolved airfoil tip shape and a square tip shape and had a semispan aspect of 4.05/1.0 with a 121.9 cm span. Free stream velocity was varied from 6.1 m/sec to 76.2 m/sec and the vortex core velocities were measured at locations 3, 6, 12, 24 and 48 chordlengths downstream of the wing trailing edge, yielding vortex ages up to 2.0 seconds. Wing pitch angles of 6, 8, 9 and 12 deg were investigated. Detailed surface pressure distributions and wing force measurements were obtained for each wing tip configuration. Correlation with vortex velocity data taken in previous experiments is good. During the rollup process, vortex core parameters appear to be dependent primarily on vortex age. Trending in the plateau and decay regions is more complex and the machanisms appear to be more unstable.

  9. Patch near field acoustic holography based on particle velocity measurements

    DEFF Research Database (Denmark)

    Zhang, Yong-Bin; Jacobsen, Finn; Bi, Chuan-Xing

    2009-01-01

    Patch near field acoustic holography (PNAH) based on sound pressure measurements makes it possible to reconstruct the source field near a source by measuring the sound pressure at positions on a surface. that is comparable in size to the source region of concern. Particle velocity is an alternative...... examines the use of particle velocity as the input of PNAH. Because the particle velocity decays faster toward the edges of the measurement aperture than the pressure does and because the wave number ratio that enters into the inverse propagator from pressure to velocity amplifies high spatial frequencies...

  10. Computerized system for building 'the rose' of the winds and defining the velocity and the average density of the wind power for a given place

    International Nuclear Information System (INIS)

    Valkov, I.; Dekova, I.; Arnaudov, A.; Kostadinov, A.

    2002-01-01

    This paper considers the structure and the working principle of a computerized system for building 'the rose' of the winds. The behaviour of the system has been experimentally investigated and on the basis of the received data 'the rose' of the winds has been built, a diagram of the average wind velocity at a predefined step in the course of time has been made, and the average density of the wind power has been quantitatively defined. The proposed system enables possibilities for creating a data base of wind parameters, their processing and graphical visualizing of the received results. The system allows to improve the work of devices of wild's wind gauge type. (authors)

  11. High-Resolution Wind Measurements for Offshore Wind Energy Development

    Science.gov (United States)

    Nghiem, Son V.; Neumann, Gregory

    2011-01-01

    A mathematical transform, called the Rosette Transform, together with a new method, called the Dense Sampling Method, have been developed. The Rosette Transform is invented to apply to both the mean part and the fluctuating part of a targeted radar signature using the Dense Sampling Method to construct the data in a high-resolution grid at 1-km posting for wind measurements over water surfaces such as oceans or lakes.

  12. Velocity measurement by vortex shedding. Contribution to the mass-flow measurement

    International Nuclear Information System (INIS)

    Martinez Piquer, T.

    1988-01-01

    The phenomenon of vortex shedding has been known for centuries and has been the subject of scientific studies for about one hundred years. It is only in the ten last years that is has been applied to the measurement of fluids velocity. In 1878 F. Strouhal observed the vortex shedding phenomenon and shown that the shedding frequency of a wire vibrating in the wind was related to the wire diameter and the wind velocity. Rayleigh, who introduced the non-dimensional Strouhal number, von Karman and Rohsko, carried out extensive work or the subject which indicated that vortex shedding could form the basis for a new type of flowmeter. The thesis describes two parallel lines of investigation which study in depth the practical applications of vortex shedding. The first one deals with the measure of velocity and it presents the novelty of a bluff body with a cross-section which has not been used until this day. This body is a circular cylinder with a two-dimensional slit along the diameter and situated in crossdirection to the fluid's stream. It possesses excellent characteristics and it is the most stable as a vortex shedder, which gives it great advantage to the rest of the shapes used until now. The detection of the vortex has been performed by measuring the pressure changes generated by the vortex on two posts situated just beside the slit. To calculate the frequency of the vortex shedding, we obtain the difference of the mentioned signals, which are the same and 180 out of phase. Finding out the period of the autocorrelation function of this signal we can estimate the velocity of the fluid. A logical equipment based on a microprocessor has been designed for the calculation using a zero-crossing time algorithm implemented in assembler language. The second line of research refers to a new method of measure mass flow. The pressure signal generated by the vortex has an intensity which is proportional to the density and to the square of the velocity. Since we have already

  13. Measuring velocity by differentiation of analog encoder signals

    NARCIS (Netherlands)

    Winarto, R.F.; Steinbuch, M.; Molengraft, van de M.J.G.

    2013-01-01

    In this report a new method for measuring velocities has been introduced. During the research in literature an overview has been made of the existing methods of measuring velocities. From this research, it can be concluded that a lot of existing approaches only work in specific settings. Besides

  14. Measuring Average Angular Velocity with a Smartphone Magnetic Field Sensor

    Science.gov (United States)

    Pili, Unofre; Violanda, Renante

    2018-01-01

    The angular velocity of a spinning object is, by standard, measured using a device called a tachometer. However, by directly using it in a classroom setting, the activity is likely to appear as less instructive and less engaging. Indeed, some alternative classroom-suitable methods for measuring angular velocity have been presented. In this paper,…

  15. Fat mass measured by DXA varies with scan velocity

    DEFF Research Database (Denmark)

    Black, Eva; Petersen, Liselotte; Kreutzer, Martin

    2002-01-01

    To study the influence of scan velocities of DXA on the measured size of fat mass, lean body mass, bone mineral content and density, and total body weight.......To study the influence of scan velocities of DXA on the measured size of fat mass, lean body mass, bone mineral content and density, and total body weight....

  16. Velocity-space sensitivity of neutron spectrometry measurements

    DEFF Research Database (Denmark)

    Jacobsen, Asger Schou; Salewski, Mirko; Eriksson, J.

    2015-01-01

    Neutron emission spectrometry (NES) measures the energies of neutrons produced in fusion reactions. Here we present velocity-space weight functions for NES and neutron yield measurements. Weight functions show the sensitivity as well as the accessible regions in velocity space for a given range...

  17. 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

  18. Effects of Velocity Parameters of the Wind on the Line Formation for 32 CYG

    Directory of Open Access Journals (Sweden)

    Kyung-Mee Kim

    1999-12-01

    Full Text Available We calculate the theoretical line profiles in order to investigate the influence of various velocity parameters. Line profiles are calculated by using the exponential velocoty law with two acceleration regions for orbital phases 0.70 and 0.06. From this compttation we find that the influence of the wind velocity gradient on a giant star is more important in the region near the star than in the region away from the star. The observed lines show stronger emission than the calculated line profiles and we interpret the difference is caused by the inhomogeniety in the atmosphere of 32 Cyg.

  19. A comparative study of calculated and measured particle velocities

    International Nuclear Information System (INIS)

    Tariq, S.M.

    2005-01-01

    After an explosive is detonated in a blast hole, seismic waves are generated in the ground surrounding the blast hole. These waves cause the particles of rock to oscillate about its position. As the wave attenuate, the particles come back to their original position. The rapidity with which the particles move is called the particle velocity. The peak or maximum velocity is the value which is of prime concern. This value of peak particle velocity can be estimated by the equations determined by the United States Bureau of Mines and by the DUPONT. A research program was conducted by the author at the 'Beck Materials Quarry' situated near Rolla, Missouri, USA. The purpose was to draw a comparison between the predicted and measured particle velocities. It was generally found that the predicted peak particle velocities were quite high as compared to the velocities measured by the Seismographs. (author)

  20. Fiber Laser for Wind Speed Measurements

    DEFF Research Database (Denmark)

    Olesen, Anders Sig

    This PhD thesis evaluates the practical construction and use of a Frequency Stepped Pulse Train modulated coherent Doppler wind lidar (FSPT lidar) for wind speed measurement. The concept of Doppler lidar is introduced as a means to measure line of sight wind speed by the Doppler shift of reflected...... Sweeper (LSFS) is introduced and analyzed as a light source for the FSPT lidar. The setup of the LSFS is discussed, and the necessary concepts for modeling and analyzing LSFS noise are developed. The model and measurements are then used to discuss the growth of optical noise in the LSFS and the impact...... on its use in the FSPT lidar. A complex ABCD model is developed and described as a method for calculating spatial and frequency dependency of a lidar’s signal strength. The model includes both spatial and temporal components of the lidar system, enabling a model capable of describing both CW, pulsed...

  1. Field measurements in the wake of a model wind turbine

    International Nuclear Information System (INIS)

    Pol, Suhas; Taylor, Amelia; Doostalab, Ali; Novoa, Santiago; Castillo, Luciano; Bilbao, Argenis; Sheng, Jian; Giesselmann, Michael; Westergaard, Carsten; Hussain, Fazle; Ren, Beibei; Glauser, Mark

    2014-01-01

    As a first step to study the dynamics of a wind farm' we experimentally explored the flow field behind a single wind turbine of diameter 1.17 m at a hub height of 6.25 m. A 10 m tower upstream of the wind farm characterizes the atmospheric conditions and its influence on the wake evolution. A vertical rake of sonic anemometers is clustered around the hub height on a second tower' 6D downstream of the turbine. We present preliminary observations from a 1- hour block of data recorded in near-neutral atmospheric conditions. The ratio of the standard deviation of power to the inflow velocity is greater than three' revealing adverse effects of inflow turbulence on the power and load fluctuations. Furthermore' the wake defect and Reynolds stress and its gradient are pronounced at 6D. The flux of energy due to Reynolds stresses is similar to that reported in wind tunnel studies. The swirl and mixing produces a constant temperature wake which results in a density jump across the wake interface. Further field measurements will explore the dynamics of a model wind farm' including the effects of atmospheric variability

  2. Measuring surface current velocities in the Agulhas region with ASAR

    CSIR Research Space (South Africa)

    Rouault, MJ

    2010-01-01

    Full Text Available is known to perform well. Although radial velocities derived from ASAR are on occasion able to represent the measured flow with incredible accuracy, the overall performance of the ASAR radial velocity product is negatively impacted by a few very large...

  3. Measurement of gas flow velocities by laser-induced gratings

    Energy Technology Data Exchange (ETDEWEB)

    Hemmerling, B; Stampanoni-Panariello, A [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Kozlov, A D.N. [General Physics Institute, Moscow (Russian Federation)

    1999-08-01

    Time resolved light scattering from laser-induced electrostrictive gratings was used for the determination of flow velocities in air at room temperature. By measuring the velocity profile across the width of a slit nozzle we demonstrated the high spatial resolution (about 200 mm) of this novel technique. (author) 3 figs., 1 ref.

  4. Plasma flow velocity measurements using a modulated Michelson interferometer

    NARCIS (Netherlands)

    Howard, J.; Meijer, F. G.

    1997-01-01

    This paper discusses the possibility of flow velocity reconstruction using passive spectroscopic techniques. We report some preliminary measurements of the toroidal flow velocity of hydrogen atoms in the RTP tokamak using a phase modulated Michelson interferometer. (C) 1997 Elsevier Science S.A.

  5. Intercalibration of HRDI and WINDII wind measurements

    Directory of Open Access Journals (Sweden)

    M. D. Burrage

    1997-09-01

    Full Text Available The High Resolution Doppler Imager (HRDI and the Wind Imaging Interferometer (WINDII in- struments, which are both on the Upper Atmosphere Research Satellite, measure winds by sensing the Doppler shift in atmospheric emission features. Because the two observation sets are frequently nearly coincident in space and time, each provides a very e.ective validation test of the other. Discrepancies due to geophysical di.erences should be much smaller than for comparisons with other techniques (radars, rockets, etc., and the very large sizes of the coincident data sets provide excellent statistics for the study. Issues that have been examined include relative systematic o.sets and the wind magnitudes obtained with the two systems. A significant zero wind position di.erence of ~6 m s–1 is identified for the zonal component, and it appears that this arises from an absolute perturbation in WINDII winds of –4 m s–1 and in HRDI of +2 m s–1. Altitude o.sets appear to be relatively small, and do not exceed 1 km. In addition, no evidence is found for the existence of a systematic wind speed bias between HRDI and WINDII. However, considerable day-to-day variability is found in the quality of the agreement, and RMS di.erences are surprisingly large, typically in the range of 20±30 m s–1.

  6. Intercalibration of HRDI and WINDII wind measurements

    Directory of Open Access Journals (Sweden)

    M. D. Burrage

    Full Text Available The High Resolution Doppler Imager (HRDI and the Wind Imaging Interferometer (WINDII in- struments, which are both on the Upper Atmosphere Research Satellite, measure winds by sensing the Doppler shift in atmospheric emission features. Because the two observation sets are frequently nearly coincident in space and time, each provides a very e.ective validation test of the other. Discrepancies due to geophysical di.erences should be much smaller than for comparisons with other techniques (radars, rockets, etc., and the very large sizes of the coincident data sets provide excellent statistics for the study. Issues that have been examined include relative systematic o.sets and the wind magnitudes obtained with the two systems. A significant zero wind position di.erence of ~6 m s–1 is identified for the zonal component, and it appears that this arises from an absolute perturbation in WINDII winds of –4 m s–1 and in HRDI of +2 m s–1. Altitude o.sets appear to be relatively small, and do not exceed 1 km. In addition, no evidence is found for the existence of a systematic wind speed bias between HRDI and WINDII. However, considerable day-to-day variability is found in the quality of the agreement, and RMS di.erences are surprisingly large, typically in the range of 20±30 m s–1.

  7. Noise measurements in 4 wind turbine farms

    International Nuclear Information System (INIS)

    Van Zuylen, E.J.; Koerts, M.

    1993-02-01

    The title wind turbine arrays are situated in Herbayum (Newinco 23PI250), Callantsoog (Bouma 160/20), Noordoostpolder (Windmaster WM300), and Ulketocht (Newinco 500 kW). Measurements were carried out by means of the so-called Ecofys Correlating Noise Meter to determine the source level of the wind turbines. The resulting source level as a function of the wind speed is interpolated to a source level for a wind speed of 8 m/s at 10 m height, on the basis of which the noise contours can be calculated. The noise contours are determined to analyze the noise load for people living in the neighbourhood of the wind parks. The source levels are compared with values as indicated in certificates, which are granted on the basis of a so-called Restricted Quality Certificate (BKC, abbreviated in Dutch) or the new standard NNI 6096/2 for the above-mentioned wind turbines. In general the results of this study agree quite well with the certified values. 12 figs., 7 tabs., 6 refs

  8. Wind Turbine Wake Characterization from Temporally Disjunct 3-D Measurements

    Directory of Open Access Journals (Sweden)

    Paula Doubrawa

    2016-11-01

    Full Text Available Scanning LiDARs can be used to obtain three-dimensional wind measurements in and beyond the atmospheric surface layer. In this work, metrics characterizing wind turbine wakes are derived from LiDAR observations and from large-eddy simulation (LES data, which are used to recreate the LiDAR scanning geometry. The metrics are calculated for two-dimensional planes in the vertical and cross-stream directions at discrete distances downstream of a turbine under single-wake conditions. The simulation data are used to estimate the uncertainty when mean wake characteristics are quantified from scanning LiDAR measurements, which are temporally disjunct due to the time that the instrument takes to probe a large volume of air. Based on LES output, we determine that wind speeds sampled with the synthetic LiDAR are within 10% of the actual mean values and that the disjunct nature of the scan does not compromise the spatial variation of wind speeds within the planes. We propose scanning geometry density and coverage indices, which quantify the spatial distribution of the sampled points in the area of interest and are valuable to design LiDAR measurement campaigns for wake characterization. We find that scanning geometry coverage is important for estimates of the wake center, orientation and length scales, while density is more important when seeking to characterize the velocity deficit distribution.

  9. Electron drift velocity measurements in liquid krypton-methane mixtures

    CERN Document Server

    Folegani, M; Magri, M; Piemontese, L

    1999-01-01

    Electron drift velocities have been measured in liquid krypton, pure and mixed with methane at different concentrations (1-10% in volume) versus electric field strength, and a possible effect of methane on electron lifetime has been investigated. While no effect on lifetime could be detected, since lifetimes were in all cases longer than what measurable, a very large increase in drift velocity (up to a factor 6) has been measured.

  10. Measurement of sound velocity profiles in fluids for process monitoring

    International Nuclear Information System (INIS)

    Wolf, M; Kühnicke, E; Lenz, M; Bock, M

    2012-01-01

    In ultrasonic measurements, the time of flight to the object interface is often the only information that is analysed. Conventionally it is only possible to determine distances or sound velocities if the other value is known. The current paper deals with a novel method to measure the sound propagation path length and the sound velocity in media with moving scattering particles simultaneously. Since the focal position also depends on sound velocity, it can be used as a second parameter. Via calibration curves it is possible to determine the focal position and sound velocity from the measured time of flight to the focus, which is correlated to the maximum of averaged echo signal amplitude. To move focal position along the acoustic axis, an annular array is used. This allows measuring sound velocity locally resolved without any previous knowledge of the acoustic media and without a reference reflector. In previous publications the functional efficiency of this method was shown for media with constant velocities. In this work the accuracy of these measurements is improved. Furthermore first measurements and simulations are introduced for non-homogeneous media. Therefore an experimental set-up was created to generate a linear temperature gradient, which also causes a gradient of sound velocity.

  11. Measurement of unsteady airflow velocity at nozzle outlet

    Science.gov (United States)

    Pyszko, René; Machů, Mário

    2017-09-01

    The paper deals with a method of measuring and evaluating the cooling air flow velocity at the outlet of the flat nozzle for cooling a rolled steel product. The selected properties of the Prandtl and Pitot sensing tubes were measured and compared. A Pitot tube was used for operational measurements of unsteady dynamic pressure of the air flowing from nozzles to abtain the flow velocity. The article also discusses the effects of air temperature, pressure and relative air humidity on air density, as well as the influence of dynamic pressure filtering on the error of averaged velocity.

  12. Prediction of velocity of the wind generation in Kobe City College of Technology; Kobe Kosen ni okeru furyoku hatsuden no yosoku

    Energy Technology Data Exchange (ETDEWEB)

    Akamatsu, K; Kanemura, M; Amako, K

    1997-11-25

    Wind conditions, such as average wind velocity for 10 minutes, maximum instantaneous wind velocity and wind directions, are measured by the anemometer and anemoscope installed 3m above the roof of the Kobe City College of Technology`s Information Processing Center building, to collect the data necessary to validate possibility of wind power generation, if the wind system is installed in the college site. Monthly availability of power is estimated from the output power characteristics curve for a generator having a rated capacity of 200W and wind velocity data collected for 9 months. It will generate power of only 144kWh, even when operated to give the rated output, or approximately 8.5kWh at the highest in a month, because of availability of wind power limited to around 30% of the total as estimated from the relative frequency distribution. It is therefore desirable to install a number of units having a rated capacity of 200W or else a smaller number of larger units. Assuming that days that give the highest output for 24 hours last 1 month, a power of 54.3kWh will be generated. It is estimated, based on these results, that a hybrid unit, in which a wind power generator installed at a high place is combined with a solar unit, can provide power required for nighttime lighting, if a wind power unit having a rated capacity of 2kW is field-controlled under an optimum condition. 13 figs., 3 tabs.

  13. How good are remote sensors at measuring extreme winds?

    NARCIS (Netherlands)

    Sathe, A.R.; Courtney, M.; Mann, J.; Wagner, R.

    2011-01-01

    This article describes some preliminary efforts within the SafeWind project, aimed to identify the possible added value of using wind lidars to detect extreme wind events. Exceptionally good performance is now regularly reported in the measurement of the mean wind speed with some wind lidars in flat

  14. Determination of the effect of wind velocity and direction changes on turbidity removal in rectangular sedimentation tanks.

    Science.gov (United States)

    Khezri, Seyed Mostafa; Biati, Aida; Erfani, Zeynab

    2012-01-01

    In the present study, a pilot-scale sedimentation tank was used to determine the effect of wind velocity and direction on the removal efficiency of particles. For this purpose, a 1:20 scale pilot simulated according to Frude law. First, the actual efficiency of total suspended solids (TSS) removal was calculated in no wind condition. Then, the wind was blown in the same and the opposite directions of water flow. At each direction TSS removal was calculated at three different velocities from 2.5 to 7 m/s. Results showed that when the wind was in the opposite direction of water flow, TSS removal efficiency initially increased with the increase of wind velocity from 0 to 2.5 m/s, then it decreased with the increase of velocity to 5 m/s. This mainly might happen because the opposite direction of wind can increase particles' retention time in the sedimentation tank. However, higher wind velocities (i.e. 3.5 and 5.5 m/s) could not increase TSS removal efficiency. Thus, if sedimentation tanks are appropriately exposed to the wind, TSS removal efficiency increases by approximately 6%. Therefore, energy consumption will be reduced by a proper site selection for sedimentation tank unit in water and waste water treatment plants.

  15. Measurement of particle velocity using a mutual inductance technique

    International Nuclear Information System (INIS)

    Kerr, Stephen; Kirkpatrick, Douglas; Garden, Steven

    2004-01-01

    Preliminary work on the development of a novel method for the measurement of particle velocity is described. The technique relies on measurement of the mutual inductance between two coaxial coils, one stationary and the other perturbed by the shock wave. The moving coil is the gauge and is deposited on thin film. The method was developed to assist in the study of particle velocities in large samples of porous media surrounding an explosive charge. The technique does not require measurements to be taken in a region of uniform magnetic field and therefore dispenses with the need for Helmholtz coils, the size and cost of which can become prohibitive for large experiments. This has the added advantage of allowing measurements to be taken at points widely dispersed through a sample with relative ease. Measurements of particle velocity in porous media have been compared with those from co-located conventional electromagnetic particle velocity gauges with reasonable agreement

  16. Doppler velocity measurements from large and small arteries of mice

    Science.gov (United States)

    Reddy, Anilkumar K.; Madala, Sridhar; Entman, Mark L.; Michael, Lloyd H.; Taffet, George E.

    2011-01-01

    With the growth of genetic engineering, mice have become increasingly common as models of human diseases, and this has stimulated the development of techniques to assess the murine cardiovascular system. Our group has developed nonimaging and dedicated Doppler techniques for measuring blood velocity in the large and small peripheral arteries of anesthetized mice. We translated technology originally designed for human vessels for use in smaller mouse vessels at higher heart rates by using higher ultrasonic frequencies, smaller transducers, and higher-speed signal processing. With these methods one can measure cardiac filling and ejection velocities, velocity pulse arrival times for determining pulse wave velocity, peripheral blood velocity and vessel wall motion waveforms, jet velocities for the calculation of the pressure drop across stenoses, and left main coronary velocity for the estimation of coronary flow reserve. These noninvasive methods are convenient and easy to apply, but care must be taken in interpreting measurements due to Doppler sample volume size and angle of incidence. Doppler methods have been used to characterize and evaluate numerous cardiovascular phenotypes in mice and have been particularly useful in evaluating the cardiac and vascular remodeling that occur following transverse aortic constriction. Although duplex ultrasonic echo-Doppler instruments are being applied to mice, dedicated Doppler systems are more suitable for some applications. The magnitudes and waveforms of blood velocities from both cardiac and peripheral sites are similar in mice and humans, such that much of what is learned using Doppler technology in mice may be translated back to humans. PMID:21572013

  17. Comparing different CFD wind turbine modelling approaches with wind tunnel measurements

    International Nuclear Information System (INIS)

    Kalvig, Siri; Hjertager, Bjørn; Manger, Eirik

    2014-01-01

    The performance of a model wind turbine is simulated with three different CFD methods: actuator disk, actuator line and a fully resolved rotor. The simulations are compared with each other and with measurements from a wind tunnel experiment. The actuator disk is the least accurate and most cost-efficient, and the fully resolved rotor is the most accurate and least cost-efficient. The actuator line method is believed to lie in between the two ends of the scale. The fully resolved rotor produces superior wake velocity results compared to the actuator models. On average it also produces better results for the force predictions, although the actuator line method had a slightly better match for the design tip speed. The open source CFD tool box, OpenFOAM, was used for the actuator disk and actuator line calculations, whereas the market leading commercial CFD code, ANSYS/FLUENT, was used for the fully resolved rotor approach

  18. Wind Atlas of Bay of Bengal with Satellite Wind Measurement

    DEFF Research Database (Denmark)

    Nadi, Navila Rahman

    footstep towards offshore wind energy analysis for this region. Generally, it is difficult to find offshore wind data relative to the wind turbine hub heights, therefore a starting point is necessary to identify the possible wind power density of the region. In such scenario, Synthetic aperture radars (SAR......The objective of this study is to obtain appropriate offshore location in the Bay of Bengal, Bangladesh for further development of wind energy. Through analyzing the previous published works, no offshore wind energy estimation has been found here. That is why, this study can be claimed as the first......) have proven useful. In this study, SAR based dataset- ENVISAT ASAR has been used for Wind Atlas generation. Furthermore, a comparative study has been performed with Global Wind Atlas (GWA) to determine a potential offshore wind farm. Additionally, the annual energy production of that offshore windfarm...

  19. Measurements of gas velocity in supersonic flow using a laser beam

    International Nuclear Information System (INIS)

    Airoldi, V.J.T.; Santos, R. dos

    1982-01-01

    A study of measurements of supersonic velocities in a wind tunnel using a laser beam was performed. Techniques using lasers are most suitable because they do not disturb the gas flow. This work presents the technique entitled as fringe technique. It works using interference patterns due to two perpendicular laser beams crossing the sample (i.e. the gas flow). Experimental results are compared with other usual techniques. (R.S.)

  20. Aerodynamical errors on tower mounted wind speed measurements due to the presence of the tower

    Energy Technology Data Exchange (ETDEWEB)

    Bergstroem, H. [Uppsala Univ. (Sweden). Dept. of Meteorology; Dahlberg, J.Aa. [Aeronautical Research Inst. of Sweden, Bromma (Sweden)

    1996-12-01

    Field measurements of wind speed from two lattice towers showed large differences for wind directions where the anemometers of both towers should be unaffected by any upstream obstacle. The wind speed was measured by cup anemometers mounted on booms along the side of the tower. A simple wind tunnel test indicates that the boom, for the studied conditions, could cause minor flow disturbances. A theoretical study, by means of simple 2D flow modelling of the flow around the mast, demonstrates that the tower itself could cause large wind flow disturbances. A theoretical study, based on simple treatment of the physics of motion of a cup anemometer, demonstrates that a cup anemometer is sensitive to velocity gradients across the cups and responds clearly to velocity gradients in the vicinity of the tower. Comparison of the results from the theoretical study and field tests show promising agreement. 2 refs, 8 figs

  1. Measuring surface flow velocity with smartphones: potential for citizen observatories

    Science.gov (United States)

    Weijs, Steven V.; Chen, Zichong; Brauchli, Tristan; Huwald, Hendrik

    2014-05-01

    Stream flow velocity is an important variable for discharge estimation and research on sediment dynamics. Given the influence of the latter on rating curves (stage-discharge relations), and the relative scarcity of direct streamflow measurements, surface velocity measurements can offer important information for, e.g., flood warning, hydropower, and hydrological science and engineering in general. With the growing amount of sensing and computing power in the hands of more outdoorsy individuals, and the advances in image processing techniques, there is now a tremendous potential to obtain hydrologically relevant data from motivated citizens. This is the main focus of the interdisciplinary "WeSenseIt" project, a citizen observatory of water. In this subproject, we investigate the feasibility of stream flow surface velocity measurements from movie clips taken by (smartphone-) cameras. First results from movie-clip derived velocity information will be shown and compared to reference measurements.

  2. Radar velocity determination using direction of arrival measurements

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin W.; Bickel, Douglas L.; Naething, Richard M.; Horndt, Volker

    2017-12-19

    The various technologies presented herein relate to utilizing direction of arrival (DOA) data to determine various flight parameters for an aircraft A plurality of radar images (e.g., SAR images) can be analyzed to identify a plurality of pixels in the radar images relating to one or more ground targets. In an embodiment, the plurality of pixels can be selected based upon the pixels exceeding a SNR threshold. The DOA data in conjunction with a measurable Doppler frequency for each pixel can be obtained. Multi-aperture technology enables derivation of an independent measure of DOA to each pixel based on interferometric analysis. This independent measure of DOA enables decoupling of the aircraft velocity from the DOA in a range-Doppler map, thereby enabling determination of a radar velocity. The determined aircraft velocity can be utilized to update an onboard INS, and to keep it aligned, without the need for additional velocity-measuring instrumentation.

  3. Continuous measurements of in-bore projectile velocity

    International Nuclear Information System (INIS)

    Asay, J.R.; Konrad, C.H.; Hall, C.A.; Shahinpoor, M.

    1989-01-01

    The application of velocity interferometry to the continuous measurement of in-bore projectile velocity in a small-bore three-stage railgun is described. These measurements are useful for determining projectile acceleration and for evaluating gun performance. The launcher employed in these studies consists of a two-stage light gas gun used to inject projectiles into a railgun for additional acceleration. Results obtained for projectile velocities to 7.4 km/s with the two-stage injector are reported and potential improvements for railgun applications are discussed

  4. Wind Tunnel Measurements at Virginia Tech

    DEFF Research Database (Denmark)

    Fischer, Andreas; Bertagnolio, Franck

    2012-01-01

    In this section, the wind tunnel configuration used for aerodynamic and aeroacoustic measurement is described. Then, the validation of the method for evaluating far-field noise from surface microphones as described in Section 5 is presented. Finally, the design concept proposed in Section 6 is ve...

  5. Wind Speed Measurement by Paper Anemometer

    Science.gov (United States)

    Zhong, Juhua; Cheng, Zhongqi; Guan, Wenchuan

    2011-01-01

    A simple wind speed measurement device, a paper anemometer, is fabricated based on the theory of standing waves. In providing the working profile of the paper anemometer, an experimental device is established, which consists of an anemometer sensor, a sound sensor, a microphone, paper strips, a paper cup, and sonic acquisition software. It shows…

  6. Some measurements of time and space correlation in wind tunnel

    Science.gov (United States)

    Favre, A; Gaviglio, J; Dumas, R

    1955-01-01

    Results are presented of research obtained by means of an apparatus for measurement of time and space correlation and of a spectral analyzer in the study of the longitudinal component of turbulence velocities in a wind tunnel downstream of a grid of meshes. Application to the case of a flat-plate boundary layer is illustrated. These researches were made at the Laboratoire de Mecanique de l'Atmosphere de l'I.M.F.M. for the O.N.E.R.A.

  7. Measurement of Poloidal Velocity on the National Spherical Torus Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Ronald E. Bell and Russell Feder

    2010-06-04

    A diagnostic suite has been developed to measure impurity poloidal flow using charge exchange recombination spectroscopy on the National Spherical Torus Experiment. Toroidal and poloidal viewing systems measure all quantities required to determine the radial electric field. Two sets of up/down symmetric poloidal views are used to measure both active emission in the plane of the neutral heating beams and background emission in a radial plane away from the neutral beams. Differential velocity measurements isolate the line-integrated poloidal velocity from apparent flows due to the energy-dependent chargeexchange cross section. Six f/1.8 spectrometers measure 276 spectra to obtain 75 active and 63 background channels every 10 ms. Local measurements from a similar midplane toroidal viewing system are mapped into two dimensions to allow the inversion of poloidal line-integrated measurements to obtain local poloidal velocity profiles. Radial resolution after inversion is 0.6-1.8 cm from the plasma edge to the center.

  8. Measurement of Poloidal Velocity on the National Spherical Torus Experiment

    International Nuclear Information System (INIS)

    Bell, Ronald E.; Feder, Russell

    2010-01-01

    A diagnostic suite has been developed to measure impurity poloidal flow using charge exchange recombination spectroscopy on the National Spherical Torus Experiment. Toroidal and poloidal viewing systems measure all quantities required to determine the radial electric field. Two sets of up/down symmetric poloidal views are used to measure both active emission in the plane of the neutral heating beams and background emission in a radial plane away from the neutral beams. Differential velocity measurements isolate the line-integrated poloidal velocity from apparent flows due to the energy-dependent chargeexchange cross section. Six f/1.8 spectrometers measure 276 spectra to obtain 75 active and 63 background channels every 10 ms. Local measurements from a similar midplane toroidal viewing system are mapped into two dimensions to allow the inversion of poloidal line-integrated measurements to obtain local poloidal velocity profiles. Radial resolution after inversion is 0.6-1.8 cm from the plasma edge to the center.

  9. Cerenkov detector for heavy-ion velocity measurements

    International Nuclear Information System (INIS)

    Olson, D.L.; Baumgartner, M.; Dufour, J.P.; Girard, J.G.; Greiner, D.E.; Lindstrom, P.J.; Symons, T.J.M.; Crawford, H.J.

    1984-08-01

    We have developed a highly sensitive velocity measuring detector using total-internal-reflection Cerenkov counters of a type mentioned by Jelly in 1958. If the velocity of the particle is above the threshold for total-internal-reflection these counters have a charge resolution of sigma = 0.18e for a 3mm thick glass radiator. For the velocity measurement we use a fused silica radiator so that the velocity of the particles are near the threshold for total-internal reflection. For momentum-analyzed projectile fragments of 1.6 GeV/nucleon 40 Ar, we have measured a mass resolution of sigma = 0.1u for isotope identification

  10. Anemometers for Mars. [Viking '75 wind measurements

    Science.gov (United States)

    Henry, R. M.; Greene, G. C.

    1974-01-01

    An investigation is conducted concerning the problems involved in the conduction of wind measurements on the planet Mars, taking into account the currently known characteristics of the Martian atmosphere. Problems introduced by the presence of the lander are examined. The suitability of several different types of anemometers for making the measurements is discussed, giving attention to rotating anemometers, sonic anemometers, ion tracers, drag force anemometers, pitot tubes, and thermal anemometers.

  11. Voyager microwave scintillation measurements of solar wind plasma parameters

    International Nuclear Information System (INIS)

    Martin, J.M.

    1985-01-01

    During the solar conjunctions of Voyager 1 and 2 spacecraft in August 1979, September 1980, and November 1982, temporal variations of intensity and frequency of the dual-wavelength (3.6 and 13 cm) radio transmissions from the spacecraft were observed and subsequently analyzed to infer characteristics of the solar wind plasma flow. Measurements of the temporal wave structure function were used to estimate the spectral index of the power law spatial spectrum of irregularities. Theoretical-intensity scintillation spectra were compared with measured intensity spectra to obtain least-squares estimates of (1) mean velocity, (2) random velocity, (3) axial ratio, and (4) electron density standard deviation. Uncertainties in parameter estimates were calculated by standard propagation of errors techniques. Mean velocity and electron density standard deviations in 1979-1980 show little dependence on solar latitude. Density standard deviation estimates were 3-10% of the background mean density and mean velocity estimates ranged from approx.200 km/s inside 17 solar radii to approx.300 km/s at 25 solar radii. 1982 density standard deviation estimates increased rapidly with latitude near 45 0 N, then sharply decreased north of that latitude, indicating the existence of a polar region of reduced fluctuations surrounded by a thin cone of strong density irregularities

  12. Burning velocity measurements of nitrogen-containing compounds.

    Science.gov (United States)

    Takizawa, Kenji; Takahashi, Akifumi; Tokuhashi, Kazuaki; Kondo, Shigeo; Sekiya, Akira

    2008-06-30

    Burning velocity measurements of nitrogen-containing compounds, i.e., ammonia (NH3), methylamine (CH3NH2), ethylamine (C2H5NH2), and propylamine (C3H7NH2), were carried out to assess the flammability of potential natural refrigerants. The spherical-vessel (SV) method was used to measure the burning velocity over a wide range of sample and air concentrations. In addition, flame propagation was directly observed by the schlieren photography method, which showed that the spherical flame model was applicable to flames with a burning velocity higher than approximately 5 cm s(-1). For CH3NH2, the nozzle burner method was also used to confirm the validity of the results obtained by closed vessel methods. We obtained maximum burning velocities (Su0,max) of 7.2, 24.7, 26.9, and 28.3 cm s(-1) for NH3, CH3NH2, C2H5NH2, and C3H7NH2, respectively. It was noted that the burning velocities of NH3 and CH3NH2 were as high as those of the typical hydrofluorocarbon refrigerants difluoromethane (HFC-32, Su0,max=6.7 cm s(-1)) and 1,1-difluoroethane (HFC-152a, Su0,max=23.6 cm s(-1)), respectively. The burning velocities were compared with those of the parent alkanes, and it was found that introducing an NH2 group into hydrocarbon molecules decreases their burning velocity.

  13. Time-dependent coolant velocity measurements in an operating BWR

    International Nuclear Information System (INIS)

    Luebbesmeyer, D.; Crowe, R.D.

    1980-01-01

    A method to measure time-dependent fluid velocities in BWR-bundle elements by noise analysis of the incore-neutron-detector signals is shown. Two application examples of the new method are given. The time behaviour of the fluid velocity in the bundle element during a scheduled power excursion of the plant. The change of power was performed by changing the coolant flow through the core The apparent change of the fluid velocity due to thermal elongation of the helix-drive of the TIP-system. A simplified mathematical model was derived for this elongation to use as a reference to check the validity of the new method. (author)

  14. A Method of Initial Velocity Measurement for Rocket Projectile

    Directory of Open Access Journals (Sweden)

    Zhang Jiancheng

    2017-01-01

    Full Text Available In this paper, a novel method is proposed to measure the initial velocity of the rocket based on STFT (the short-time Fourier transform and the WT (wavelet transform. The radar echo signal processing procedure involves the following steps: sampling process, overlapping windows, wavelet decomposition and reconstruction, computing FFT (Fast Fourier Transform and spectrum analysis, power spectrum peak detection. Then, according to the peak of the detection power spectrum, the corresponding Doppler frequency is obtained. Finally, on the basis of the relationship between Doppler frequency and instantaneous velocity, the V-T curve is drawn in MATLAB to obtain the initial velocity of the rocket muzzle.

  15. Measurement bias of fluid velocity in molecular simulations

    International Nuclear Information System (INIS)

    Tysanner, Martin W.; Garcia, Alejandro L.

    2004-01-01

    In molecular simulations of fluid flow, the measurement of mean fluid velocity is considered to be a straightforward computation, yet there is some ambiguity in its definition. We show that in systems far from equilibrium, such as those with large temperature or velocity gradients, two commonly used definitions give slightly different results. Specifically, a bias can arise when computing the mean fluid velocity by measuring the mean particle velocity in a cell and averaging this mean over samples. We show that this bias comes from the correlation of momentum and density fluctuations in non-equilibrium fluids, obtain an analytical expression for predicting it, and discuss what system characteristics (e.g., number of particles per cell, temperature gradients) reduce or magnify the error. The bias has a physical origin so although we demonstrate it by direct simulation Monte Carlo (DSMC) computations, the same effect will be observed with other particle-based simulation methods, such as molecular dynamics and lattice gases

  16. Influence of wind conditions on wind turbine loads and measurement of turbulence using lidars

    NARCIS (Netherlands)

    Sathe, A.R.

    2012-01-01

    Variations in wind conditions influence the loads on wind turbines significantly. In order to determine these loads it is important that the external conditions are well understood. Wind lidars are well developed nowadays to measure wind profiles upwards from the surface. But how turbulence can be

  17. Measurements of electron drift velocity in pure isobutane

    Energy Technology Data Exchange (ETDEWEB)

    Vivaldini, Tulio C.; Lima, Iara B.; Goncalves, Josemary A.C.; Botelho, Suzana; Tobias, Carmen C.B., E-mail: ccbueno@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Ridenti, Marco A.; Pascholati, Paulo R. [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Fisica. Lab. do Acelerador Linear; Fonte, Paulo; Mangiarotti, Alessio [Universidade de Coimbra (Portugal). Dept de Fisica. Lab. de Instrumentacao e Fisica Experimental de Particulas

    2009-07-01

    In this work we report on preliminary results related to the dependence of the electron drift velocity for pure isobutane as a function of reduced electric field (E/N) in the range from 100 Td up to 216 Td. The measurements of electron drift velocity were based on the Pulsed Townsend technique. In order to validate the technique and analyzing non-uniformity effects, results for nitrogen are also presented and compared with a numerical simulation of the Bolsig+ code. (author)

  18. Measurements of electron drift velocity in pure isobutane

    International Nuclear Information System (INIS)

    Vivaldini, Tulio C.; Lima, Iara B.; Goncalves, Josemary A.C.; Botelho, Suzana; Tobias, Carmen C.B.; Ridenti, Marco A.; Pascholati, Paulo R.; Fonte, Paulo; Mangiarotti, Alessio

    2009-01-01

    In this work we report on preliminary results related to the dependence of the electron drift velocity for pure isobutane as a function of reduced electric field (E/N) in the range from 100 Td up to 216 Td. The measurements of electron drift velocity were based on the Pulsed Townsend technique. In order to validate the technique and analyzing non-uniformity effects, results for nitrogen are also presented and compared with a numerical simulation of the Bolsig+ code. (author)

  19. Free-surface velocity measurements using an optically recording velocity interferometer

    International Nuclear Information System (INIS)

    Lu Jianxin; Wang Zhao; Liang Jing; Shan Yusheng; Zhou Chuangzhi; Xiang Yihuai; Lu Ze; Tang Xiuzhang

    2006-01-01

    An optically recording velocity interferometer system (ORVIS) was developed for the free-surface velocity measurements in the equation of state experiments. The time history of free-surface velocity could be recorded by the electronic streak camera. In the experiments, ORVIS got a 179 ps time resolution, and a higher time resolution could be got by minimizing the delay time. The equation of state experiments were carried out on the high power excimer laser system called 'Heaven I' with laser wavelength of 248.4 nm, pulse duration of 25 ns and maximum energy 158 J. Free-surface velocity of 20 μm thick iron got 3.86 km/s with laser intensity of 6.24 x 10 11 W·cm -2 , and free-surface velocity of 100 μm thick aluminum with 100 μm CH foil at the front got 2.87 km/s with laser intensity 7.28 x 10 11 W·cm -2 . (authors)

  20. Measuring average angular velocity with a smartphone magnetic field sensor

    Science.gov (United States)

    Pili, Unofre; Violanda, Renante

    2018-02-01

    The angular velocity of a spinning object is, by standard, measured using a device called a tachometer. However, by directly using it in a classroom setting, the activity is likely to appear as less instructive and less engaging. Indeed, some alternative classroom-suitable methods for measuring angular velocity have been presented. In this paper, we present a further alternative that is smartphone-based, making use of the real-time magnetic field (simply called B-field in what follows) data gathering capability of the B-field sensor of the smartphone device as the timer for measuring average rotational period and average angular velocity. The in-built B-field sensor in smartphones has already found a number of uses in undergraduate experimental physics. For instance, in elementary electrodynamics, it has been used to explore the well-known Bio-Savart law and in a measurement of the permeability of air.

  1. Measurement of LBE flow velocity profile by UDVP

    International Nuclear Information System (INIS)

    Kikuchi, Kenji; Takeda, Yasushi; Obayashi, Hiroo; Tezuka, Masao; Sato, Hiroshi

    2006-01-01

    Measurements of liquid metal lead-bismuth eutectic (LBE), flow velocity profile were realized in the spallation neutron source target model by the ultrasonic Doppler velocity profiler (UVDP) technique. So far, it has not been done well, because both of poor wetting property of LBE with stainless steels and poor performance of supersonic probes at high temperatures. The measurement was made for a return flow in the target model, which has coaxially arranged annular and tube channels, in the JAEA Lead Bismuth Loop-2 (JLBL-2). The surface treatment of LBE container was examined. It was found that the solder coating was effective to enhance an intensity of reflected ultrasonic wave. This treatment has been applied to the LBE loop, which was operated up to 150 deg. C. The electro magnetic pump generates LBE flow and the flow rate was measured by the electro magnetic flow meter. By changing the flow rate of LBE, velocity profiles in the target were measured. It was confirmed that the maximum velocity in the time-averaged velocity distribution on the target axis was proportional to the flow rate measured by the electro magnetic flow meter

  2. On the measurements of large scale solar velocity fields

    International Nuclear Information System (INIS)

    Andersen, B.N.

    1985-01-01

    A general mathematical formulation for the correction of the scattered light influence on solar Doppler shift measurements has been developed. This method has been applied to the straylight correction of measurements of solar rotation, limb effect, large scale flows and oscillations. It is shown that neglecting the straylight errors may cause spurious large scale velocity fields, oscillations and erronous values for the solar rotation and limb effect. The influence of active regions on full disc velocity measurements has been studied. It is shown that a 13 day periodicity in the global velocity signal will be introduced by the passage of sunspots over the solar disc. With different types of low resolution apertures, other periodicities may be introduced. Accurate measurements of the center-to-limb velocity shift are presented for a set of magnetic insensitive lines well suited for solar velocity measurements. The absolute wavelenght shifts are briefly discussed. The stronger lines have a ''supergravitational'' shift of 300-400 m/s at the solar limb. The results may be explained by the presence of a 20-25 m/s poleward meridional flow and a latitudinal dependence of the granular parameters. Using a simple model it is shown that the main properites of the observations are explained by a 5% increase in the granular size with latitude. Data presented indicate that the resonance line K I, 769.9 nm has a small but significant limb effect of 125 m/s from center to limb

  3. Measurements in support of wind farm simulations and power forecasts: The Crop/Wind-energy Experiments (CWEX)

    International Nuclear Information System (INIS)

    Takle, E S; Rajewski, D A; Lundquist, J K; Gallus, W A Jr; Sharma, A

    2014-01-01

    The Midwest US currently is experiencing a large build-out of wind turbines in areas where the nocturnal low-level jet (NLLJ) is a prominent and frequently occurring feature. We describe shear characteristics of the NLLJ and their influence on wind power production. Reports of individual turbine power production and concurrent measurements of near-surface thermal stratification are used to turbine wake interactions and turbine interaction with the overlying atmosphere. Progress in forecasting conditions such as wind ramps and shear are discussed. Finally, the pressure perturbation introduced by a line of turbines produces surface flow convergence that may create a vertical velocity and hence a mesoscale influence on cloud formation by a wind farm

  4. Using embedded fibers to measure explosive detonation velocities

    Energy Technology Data Exchange (ETDEWEB)

    Podsednik, Jason W.; Parks, Shawn Michael; Navarro, Rudolfo J.

    2012-07-01

    Single-mode fibers were cleverly embedded into fixtures holding nitromethane, and used in conjunction with a photonic Doppler velocimeter (PDV) to measure the associated detonation velocity. These measurements have aided us in our understanding of energetic materials and enhanced our diagnostic capabilities.

  5. Estimating Radar Velocity using Direction of Arrival Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Horndt, Volker [General Atomics Aeronautical Systems, Inc., San Diego, CA (United States); Bickel, Douglas Lloyd [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Naething, Richard M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-09-01

    Direction of Arrival (DOA) measurements, as with a monopulse antenna, can be compared against Doppler measurements in a Synthetic Aperture Radar ( SAR ) image to determine an aircraft's forward velocity as well as its crab angle, to assist the aircraft's navigation as well as improving high - performance SAR image formation and spatial calibration.

  6. Temperature And Wind Velocity Oscillations Along a Gentle Slope During Sea-Breeze Events

    Science.gov (United States)

    Bastin, Sophie; Drobinski, Philippe

    2005-03-01

    The flow structure on a gentle slope at Vallon d’Ol in the northern suburbs of Marseille in southern France has been documented by means of surface wind and temperature measurements collected from 7 June to 14 July 2001 during the ESCOMPTE experiment. The analysis of the time series reveals temperature and wind speed oscillations during several nights (about 60--90 min oscillation period) and several days (about 120-180 min oscillation period) during the whole observing period. Oscillating katabatic winds have been reported in the literature from theoretical, experimental and numerical studies. In the present study, the dynamics of the observed oscillating katabatic winds are in good agreement with the theory.In contrast to katabatic winds, no daytime observations of oscillating anabatic upslope flows have ever been published to our knowledge, probably because of temperature inversion break-up that inhibits upslope winds. The present paper shows that cold air advection by a sea breeze generates a mesoscale horizontal temperature gradient, and hence baroclinicity in the atmosphere, which then allows low-frequency oscillations, similar to a katabatic flow. An expression for the oscillation period is derived that accounts for the contribution of the sea-breeze induced mesoscale horizontal temperature gradient. The theoretical prediction of the oscillation period is compared to the measurements, and good agreement is found. The statistical analysis of the wind flow at Vallon d’Ol shows a dominant north-easterly to easterly flow pattern for nighttime oscillations and a dominant south-westerly flow pattern for daytime oscillations. These results are consistent with published numerical simulation results that show that the air drains off the mountain along the maximum slope direction, which in the studied case is oriented south-west to north-east.

  7. Measuring gas concentration and wind intensity in a turbulent wind tunnel with a mobile robot

    OpenAIRE

    Martínez Lacasa, Daniel; Moreno Blanc, Javier; Tresánchez, Marcel; Clotet Bellmunt, Eduard; Jiménez-Soto, Juan M.; Magrans, Rudys; Pardo Martínez, Antonio; Marco Colás, Santiago; Palacín Roca, Jordi

    2016-01-01

    This paper presents themeasurement of gas concentration and wind intensity performed with amobile robot in a customturbulent wind tunnel designed for experimentation with customizable wind and gas leak sources.This paper presents the representation in different information layers of the measurements obtained in the turbulent wind tunnel under different controlled environmental conditions in order to describe the plume of the gas and wind intensities inside the experimentation chamber...

  8. Measurement of the neutrino velocity in OPERA experiment

    Energy Technology Data Exchange (ETDEWEB)

    Dracos, M., E-mail: marcos.dracos@in2p3.fr [IPHC, Université de Strasbourg, CNRS/IN2P3, F-67037 Strasbourg (France)

    2013-02-15

    The OPERA neutrino experiment has measured the neutrino velocity using the CERN CNGS beam over a baseline of 730 km. The measurement is based on data taken by OPERA in the years 2009, 2010, 2011. An arrival time of CNGS muon neutrinos with respect to the one computed assuming the speed of light in vacuum of (6.5±7.4(stat.){sub −8.0}{sup +8.3}(sys.))ns was measured corresponding to a relative difference of the muon neutrino velocity with respect to the speed of light (v−c)/c=(2.7±3.1(stat.){sub −3.3}{sup +3.4}(sys.))×10{sup −6}. During spring 2012 the CNGS provided during two weeks a short proton bunched beam dedicated to the neutrino velocity measurement. The OPERA neutrino experiment at the underground Gran Sasso Laboratory has measured the velocity of neutrinos with slightly modified setup compared to 2011 measurements. These modifications increased the timing accuracy and also fixed previous problems. The arrival time of CNGS muon neutrinos with respect to the one computed assuming the speed of light in vacuum has been found to be in agreement with the previous measurement. This result confirms the revised OPERA result and that indeed the neutrino anticipation announced in September 2011 was due to technical problems.

  9. PIV Measurements of Flows around the Wind Turbines with a Flanged-Diffuser Shroud

    Institute of Scientific and Technical Information of China (English)

    Kazuhiko Toshimitsu; Koutarou Nishikawa; Wataru Haruki; Shinichi Oono; Manabu Takao; Yuji Ohya

    2008-01-01

    The wind turbines with a flanged-diffuser shroud -so called "wind lens turbine"- are developed as one of high performance wind turbines by Ohya et al. In order to investigate the flow characteristics and flow acceleration, the paper presents the flow velocity measurements of a long-type and a compact-type wind turbines with a flanged-diffuser shroud by particle image velocimetry. In the case of the long type wind turbine, the velocity vec-tors of the inner flow field of the diffuser for turbine blades rotating and no blades rotating are presented at Rey-nolds number, 0.9x105. Furthermore the flow fields between with and without rotating are compared. Through the PIV measurement results, one can realize that the turbine blades rotating affects as suppress the disturbance and the flow separation near the inner wall of the diffuser. The time average velocity vectors are made on the av-erage of the instantaneous velocity data. There are two large vortices in downstream region of the diffuser. One vortex behind the flange acts as suck in wind to the diffuser and raise the inlet flow velocity. Another large vortex appears in downstream. It might be act as blockage vortex of main flow. The large blockage vortex is not clear in the instantaneous velocity vectors, however it exists clearly in the time average flow field. The flow field around the wind turbine with a compact-type flanged-diffuser shroud is also investigated. The flow pattern behind the flange of the compact-type turbine is the same as the long-type one. It means that the effect of flow acceleration is caused by the unsteady vortices behind the flange. The comparison with CFD and PIV results of meridional time-average streamlines after the compact-type diffuser is also presented.

  10. 3D WindScanner lidar measurements of wind and turbulence around wind turbines, buildings and bridges

    Science.gov (United States)

    Mikkelsen, T.; Sjöholm, M.; Angelou, N.; Mann, J.

    2017-12-01

    WindScanner is a distributed research infrastructure developed at DTU with the participation of a number of European countries. The research infrastructure consists of a mobile technically advanced facility for remote measurement of wind and turbulence in 3D. The WindScanners provide coordinated measurements of the entire wind and turbulence fields, of all three wind components scanned in 3D space. Although primarily developed for research related to on- and offshore wind turbines and wind farms, the facility is also well suited for scanning turbulent wind fields around buildings, bridges, aviation structures and of flow in urban environments. The mobile WindScanner facility enables 3D scanning of wind and turbulence fields in full scale within the atmospheric boundary layer at ranges from 10 meters to 5 (10) kilometers. Measurements of turbulent coherent structures are applied for investigation of flow pattern and dynamical loads from turbines, building structures and bridges and in relation to optimization of the location of, for example, wind farms and suspension bridges. This paper presents our achievements to date and reviews briefly the state-of-the-art of the WindScanner measurement technology with examples of uses for wind engineering applications.

  11. 3D wake measurements from a scanning wind lidar in combination with a fast wind field reconstruction model

    DEFF Research Database (Denmark)

    Mikkelsen, Torben Krogh; Herges, T. G.; Astrup, Poul

    2017-01-01

    University of Denmark. The purpose of the SpinnerLidar measurements at SWIFT is to measure the response of a V27 turbine wake to varying inflow conditions and turbine operating states. Although our fast scanning SpinnerLidar is able to measure the line-of-sight projected wind speed at up to 400 points per......-Stokes CFD code “Lincom Cyclop-buster model,”3 the corresponding 3D wind vector field (u, v, w) can be reconstructed under constraints for conservation of mass and momentum. The resulting model calculated line-of-sight projections of the 3D wind velocity vectors will become consistent with the line...

  12. Validation of the Eddy Viscosity and Lange Wake Models using Measured Wake Flow Characteristics Behind a Large Wind Turbine Rotor

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Sang Hyeon; Kim, Bum Suk; Huh, Jong Chul [Jeju National Univ., Jeju (Korea, Republic of); Go, Young Jun [Hanjin Ind, Co., Ltd., Yangsan (Korea, Republic of)

    2016-01-15

    The wake effects behind wind turbines were investigated by using data from a Met Mast tower and the SCADA (Supervisory Control and Data Acquisition) system for a wind turbine. The results of the wake investigations and predicted values for the velocity deficit based on the eddy viscosity model were compared with the turbulence intensity from the Lange model. As a result, the velocity deficit and turbulence intensity of the wake increased as the free stream wind speed decreased. In addition, the magnitude of the velocity deficit for the center of the wake using the eddy viscosity model was overestimated while the turbulence intensity from the Lange model showed similarities with measured values.

  13. Optic-microwave mixing velocimeter for superhigh velocity measurement

    International Nuclear Information System (INIS)

    Weng Jidong; Wang Xiang; Tao Tianjiong; Liu Cangli; Tan Hua

    2011-01-01

    The phenomenon that a light beam reflected off a moving object experiences a Doppler shift in its frequency underlies practical interferometric techniques for remote velocity measurements, such as velocity interferometer system for any reflector (VISAR), displacement interferometer system for any reflector (DISAR), and photonic Doppler velocimetry (PDV). While VISAR velocimeters are often bewildered by the fringe loss upon high-acceleration dynamic process diagnosis, the optic-fiber velocimeters such as DISAR and PDV, on the other hand, are puzzled by high velocity measurement over 10 km/s, due to the demand for the high bandwidth digitizer. Here, we describe a new optic-microwave mixing velocimeter (OMV) for super-high velocity measurements. By using currently available commercial microwave products, we have constructed a simple, compact, and reliable OMV device, and have successfully obtained, with a digitizer of bandwidth 6 GH only, the precise velocity history of an aluminum flyer plate being accelerated up to 11.2 km/s in a three stage gas-gun experiment.

  14. Illumination Profile & Dispersion Variation Effects on Radial Velocity Measurements

    Science.gov (United States)

    Grieves, Nolan; Ge, Jian; Thomas, Neil B.; Ma, Bo; Li, Rui; SDSS-III

    2015-01-01

    The Multi-object APO Radial-Velocity Exoplanet Large-Area Survey (MARVELS) measures radial velocities using a fiber-fed dispersed fixed-delay interferometer (DFDI) with a moderate dispersion spectrograph. This setup allows a unique insight into the 2D illumination profile from the fiber on to the dispersion grating. Illumination profile investigations show large changes in the profile over time and fiber location. These profile changes are correlated with dispersion changes and long-term radial velocity offsets, a major problem within the MARVELS radial velocity data. Characterizing illumination profiles creates a method to both detect and correct radial velocity offsets, allowing for better planet detection. Here we report our early results from this study including improvement of radial velocity data points from detected giant planet candidates. We also report an illumination profile experiment conducted at the Kitt Peak National Observatory using the EXPERT instrument, which has a DFDI mode similar to MARVELS. Using profile controlling octagonal-shaped fibers, long term offsets over a 3 month time period were reduced from ~50 m/s to within the photon limit of ~4 m/s.

  15. Hemodynamic study of ischemic limb by velocity measurement in foot

    International Nuclear Information System (INIS)

    Shionoya, S.; Hirai, M.; Kawai, S.; Ohta, T.; Seko, T.

    1981-01-01

    By means of a tracer technique with 99mTc-pertechnetate, provided with seven zonal regions of interest, 6 mm in width, placed at equal spaces of 18 mm, from the toe tip to the midfoot at a right angle to the long axis of the foot, arterial flow velocity in the foot during reactive hyperemia was measured. The mean velocity in the foot was 5.66 +/- 1.78 cm/sec in 14 normal limbs, 1.58 +/- 1.07 cm/sec in 29 limbs with distal thromboangiitis obliterans (TAO), 0.89 +/- 0.61 cm/sec in 13 limbs with proximal TAO, and 0.97 +/- 0.85 cm/sec in 15 limbs with arteriosclerosis obliterans (ASO). The velocity returned to normal in all 12 limbs after successful arterial reconstruction, whereas the foot or toe blood pressure remained pathologic in 9 of the 12 limbs postoperatively; the velocity reverted to normal in 4 of 13 limbs after lumbar sympathectomy. When the velocity was normalized after operation, the ulceration healed favorably, and the ischemic limb was salvaged. The most characteristic feature of peripheral arterial occlusive disease of the lower extremity was a stagnation of arterial circulation in the foot, and the flow velocity in the foot was a sensitive predictive index of limb salvage

  16. Quantifying error of lidar and sodar Doppler beam swinging measurements of wind turbine wakes using computational fluid dynamics

    Science.gov (United States)

    Lundquist, J. K.; Churchfield, M. J.; Lee, S.; Clifton, A.

    2015-02-01

    Wind-profiling lidars are now regularly used in boundary-layer meteorology and in applications such as wind energy and air quality. Lidar wind profilers exploit the Doppler shift of laser light backscattered from particulates carried by the wind to measure a line-of-sight (LOS) velocity. The Doppler beam swinging (DBS) technique, used by many commercial systems, considers measurements of this LOS velocity in multiple radial directions in order to estimate horizontal and vertical winds. The method relies on the assumption of homogeneous flow across the region sampled by the beams. Using such a system in inhomogeneous flow, such as wind turbine wakes or complex terrain, will result in errors. To quantify the errors expected from such violation of the assumption of horizontal homogeneity, we simulate inhomogeneous flow in the atmospheric boundary layer, notably stably stratified flow past a wind turbine, with a mean wind speed of 6.5 m s-1 at the turbine hub-height of 80 m. This slightly stable case results in 15° of wind direction change across the turbine rotor disk. The resulting flow field is sampled in the same fashion that a lidar samples the atmosphere with the DBS approach, including the lidar range weighting function, enabling quantification of the error in the DBS observations. The observations from the instruments located upwind have small errors, which are ameliorated with time averaging. However, the downwind observations, particularly within the first two rotor diameters downwind from the wind turbine, suffer from errors due to the heterogeneity of the wind turbine wake. Errors in the stream-wise component of the flow approach 30% of the hub-height inflow wind speed close to the rotor disk. Errors in the cross-stream and vertical velocity components are also significant: cross-stream component errors are on the order of 15% of the hub-height inflow wind speed (1.0 m s-1) and errors in the vertical velocity measurement exceed the actual vertical velocity

  17. Results of Sexbierum Wind Farm: single wake measurements

    NARCIS (Netherlands)

    Cleijne, J.W.

    1993-01-01

    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

  18. Analysis of trends between solar wind velocity and energetic electron fluxes at geostationary orbit using the reverse arrangement test

    Science.gov (United States)

    Aryan, Homayon; Boynton, Richard J.; Walker, Simon N.

    2013-02-01

    A correlation between solar wind velocity (VSW) and energetic electron fluxes (EEF) at the geosynchronous orbit was first identified more than 30 years ago. However, recent studies have shown that the relation between VSW and EEF is considerably more complex than was previously suggested. The application of process identification technique to the evolution of electron fluxes in the range 1.8 - 3.5 MeV has also revealed peculiarities in the relation between VSW and EEF at the geosynchronous orbit. It has been revealed that for a constant solar wind density, EEF increase with VSW until a saturation velocity is reached. Beyond the saturation velocity, an increase in VSW is statistically not accompanied with EEF enhancement. The present study is devoted to the investigation of saturation velocity and its dependency upon solar wind density using the reverse arrangement test. In general, the results indicate that saturation velocity increases as solar wind density decreases. This implies that solar wind density plays an important role in defining the relationship between VSW and EEF at the geosynchronous orbit.

  19. Velocity and rotation measurements in acoustically levitated droplets

    Energy Technology Data Exchange (ETDEWEB)

    Saha, Abhishek [University of Central Florida, Orlando, FL 32816 (United States); Basu, Saptarshi [Indian Institute of Science, Bangalore 560012 (India); Kumar, Ranganathan, E-mail: ranganathan.kumar@ucf.edu [University of Central Florida, Orlando, FL 32816 (United States)

    2012-10-01

    The velocity scale inside an acoustically levitated droplet depends on the levitator and liquid properties. Using Particle Imaging Velocimetry (PIV), detailed velocity measurements have been made in a levitated droplet of different diameters and viscosity. The maximum velocity and rotation are normalized using frequency and amplitude of acoustic levitator, and droplet viscosity. The non-dimensional data are fitted for micrometer- and millimeter-sized droplets levitated in different levitators for different viscosity fluids. It is also shown that the rotational speed of nanosilica droplets at an advanced stage of vaporization compares well with that predicted by exponentially fitted parameters. -- Highlights: ► Demonstrates the importance of rotation in a levitated droplet that leads to controlled morphology. ► Provides detailed measurements of Particle Image Velocimetry inside levitated droplets. ► Shows variation of vortex strength with the droplet diameter and viscosity of the liquid.

  20. Velocity and rotation measurements in acoustically levitated droplets

    International Nuclear Information System (INIS)

    Saha, Abhishek; Basu, Saptarshi; Kumar, Ranganathan

    2012-01-01

    The velocity scale inside an acoustically levitated droplet depends on the levitator and liquid properties. Using Particle Imaging Velocimetry (PIV), detailed velocity measurements have been made in a levitated droplet of different diameters and viscosity. The maximum velocity and rotation are normalized using frequency and amplitude of acoustic levitator, and droplet viscosity. The non-dimensional data are fitted for micrometer- and millimeter-sized droplets levitated in different levitators for different viscosity fluids. It is also shown that the rotational speed of nanosilica droplets at an advanced stage of vaporization compares well with that predicted by exponentially fitted parameters. -- Highlights: ► Demonstrates the importance of rotation in a levitated droplet that leads to controlled morphology. ► Provides detailed measurements of Particle Image Velocimetry inside levitated droplets. ► Shows variation of vortex strength with the droplet diameter and viscosity of the liquid.

  1. Optical-fiber interferometer for velocity measurements with picosecond resolution

    International Nuclear Information System (INIS)

    Weng Jidong; Tan Hua; Wang Xiang; Ma Yun; Hu Shaolou; Wang Xiaosong

    2006-01-01

    The conventional Doppler laser-interference velocimeters are made up of traditional optical elements such as lenses and mirrors and will generally restrict its applications in multipoint velocity measurements. By transfering the light from multimode optical fiber to single-mode optical fiber and using the currently available conventional telecommunications elements, the authors have constructed a velocimeter called all-fiber displacement interferometer system for any reflector. The unique interferometer system is only made up of fibers or fiber-coupled components. The viability of this technique is demonstrated by measuring the velocity of an interface moving at velocity of 2133 m/s with 50 ps time resolution. In addition, the concept of optical-fiber mode conversion would provide a way to develop various optical-fiber sensors

  2. Coherence measures in automatic time-migration velocity analysis

    International Nuclear Information System (INIS)

    Maciel, Jonathas S; Costa, Jessé C; Schleicher, Jörg

    2012-01-01

    Time-migration velocity analysis can be carried out automatically by evaluating the coherence of migrated seismic events in common-image gathers (CIGs). The performance of gradient methods for automatic time-migration velocity analysis depends on the coherence measures used as the objective function. We compare the results of four different coherence measures, being conventional semblance, differential semblance, an extended differential semblance using differences of more distant image traces and the product of the latter with conventional semblance. In our numerical experiments, the objective functions based on conventional semblance and on the product of conventional semblance with extended differential semblance provided the best velocity models, as evaluated by the flatness of the resulting CIGs. The method can be easily extended to anisotropic media. (paper)

  3. Offshore wind resources at Danish measurement sites

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-03-01

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

  4. Wind direction/velocity and current direction/velocity data from current meter casts in a world wide distribution from 1970-12-06 to 1991-10-01 (NODC Accession 9700218)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Wind direction/velocity and current direction/velocity data were collected using current meter casts in a world wide distribution from December 6, 1970 to October 1,...

  5. Full scale measurement of wind induced pressures : 1 configuration of wind induced pressures

    NARCIS (Netherlands)

    Geurts, C.P.W.; Wijen, H.L.M.

    1994-01-01

    A research project 10 the spectral characteristics of wind induced pressures is in progress in Eindhoven. This project includes both wind tunnel and full scale measurements. Wind induced pressures are measured in full scale at the main building of Eindhoven University of Technology. This paper

  6. Poloidal rotation velocity measurement in toroidal plasmas via microwave reflectometry

    International Nuclear Information System (INIS)

    Pavlichenko, O.S.; Skibenko, A.I.; Fomin, I.P.; Pinos, I.B.; Ocheretenko, V.L.; Berezhniy, V.L.

    2001-01-01

    Results of experiment modeling backscattering of microwaves from rotating plasma layer perturbed by fluctuations are presented. It was shown that auto- and crosscorrelation of reflected power have a periodicity equal to rotation period. Such periodicity was observed by microwave reflectometry in experiments on RF plasma production on U-3M torsatron and was used for measurement of plasma poloidal rotation velocity. (author)

  7. MEASURING EJECTA VELOCITY IMPROVES TYPE Ia SUPERNOVA DISTANCES

    International Nuclear Information System (INIS)

    Foley, Ryan J.; Kasen, Daniel

    2011-01-01

    We use a sample of 121 spectroscopically normal Type Ia supernovae (SNe Ia) to show that their intrinsic color is correlated with their ejecta velocity, as measured from the blueshift of the Si II λ6355 feature near maximum brightness, v SiII . The SN Ia sample was originally used by Wang et al. to show that the relationship between color excess and peak magnitude, which in the absence of intrinsic color differences describes a reddening law, was different for two subsamples split by v SiII (defined as 'Normal' and 'High Velocity'). We verify this result, but find that the two subsamples have the same reddening law when extremely reddened events (E(B - V)>0.35 mag) are excluded. We also show that (1) the High-Velocity subsample is offset by ∼0.06 mag to the red from the Normal subsample in the (B max - V max )-M V plane, (2) the B max - V max cumulative distribution functions of the two subsamples have nearly identical shapes, but the High-Velocity subsample is offset by ∼0.07 mag to the red in B max - V max , and (3) the bluest High-Velocity SNe Ia are ∼0.10 mag redder than the bluest Normal SNe Ia. Together, this evidence indicates a difference in intrinsic color for the subsamples. Accounting for this intrinsic color difference reduces the scatter in Hubble residuals from 0.190 mag to 0.130 mag for SNe Ia with A V ∼ V found in large SN Ia samples. We explain the correlation between ejecta velocity and color as increased line blanketing in the High-Velocity SNe Ia, causing them to become redder. We discuss some implications of this result, and stress the importance of spectroscopy for future SN Ia cosmology surveys, with particular focus on the design of WFIRST.

  8. 3D WindScanner lidar measurements of wind and turbulence around wind turbines, buildings and bridges

    DEFF Research Database (Denmark)

    Mikkelsen, Torben Krogh; Sjöholm, Mikael; Angelou, Nikolas

    2017-01-01

    WindScanner is a distributed research infrastructure developed at DTU with the participation of a number of European countries. The research infrastructure consists of a mobile technically advanced facility for remote measurement of wind and turbulence in 3D. The WindScanners provide coordinated...... structures and of flow in urban environments. The mobile WindScanner facility enables 3D scanning of wind and turbulence fields in full scale within the atmospheric boundary layer at ranges from 10 meters to 5 (10) kilometers. Measurements of turbulent coherent structures are applied for investigation...

  9. An inexpensive instrument for measuring wave exposure and water velocity

    Science.gov (United States)

    Figurski, J.D.; Malone, D.; Lacy, J.R.; Denny, M.

    2011-01-01

    Ocean waves drive a wide variety of nearshore physical processes, structuring entire ecosystems through their direct and indirect effects on the settlement, behavior, and survivorship of marine organisms. However, wave exposure remains difficult and expensive to measure. Here, we report on an inexpensive and easily constructed instrument for measuring wave-induced water velocities. The underwater relative swell kinetics instrument (URSKI) is a subsurface float tethered by a short (<1 m) line to the seafloor. Contained within the float is an accelerometer that records the tilt of the float in response to passing waves. During two field trials totaling 358 h, we confirmed the accuracy and precision of URSKI measurements through comparison to velocities measured by an in situ acoustic Doppler velocimeter and those predicted by a standard swell model, and we evaluated how the dimensions of the devices, its buoyancy, and sampling frequency can be modified for use in a variety of environments.

  10. Extraction of Poloidal Velocity from Charge Exchange Recombination Spectroscopy Measurements

    International Nuclear Information System (INIS)

    Solomon, W.M.; Burrell, K.H.; Gohil, P.; Groebner, R.J.; Baylor, L.R.

    2004-01-01

    A novel approach has been implemented on DIII-D to allow the correct determination of the plasma poloidal velocity from charge exchange spectroscopy measurements. Unlike usual techniques, the need for detailed atomic physics calculations to properly interpret the results is alleviated. Instead, the needed atomic physics corrections are self-consistently determined directly from the measurements, by making use of specially chosen viewing chords. Modeling results are presented that were used to determine a set of views capable of measuring the correction terms. We present the analysis of a quiescent H-mode discharge, illustrating that significant modifications to the velocity profiles are required in these high ion temperature conditions. We also present preliminary measurements providing the first direct comparison of the standard cross-section correction to the atomic physics calculations

  11. Analysis of Anholt offshore wind farm SCADA measurements

    DEFF Research Database (Denmark)

    Hansen, Kurt Schaldemose; Volker, Patrick; Pena Diaz, Alfredo

    SCADA measurements from the Danish Anholt offshore wind farm (ANH) for a period of 2½ years have been qualified. ANH covers 12 km × 22 km and is located between Djursland and the island Anholt in Kattegat, Denmark. This qualification encompasses identification of curtailment and idling periods......, start/stop events and a power curve control for each wind turbine in the wind farm. Data also include wind speed measurements from a nearby WindCube lidar and simulations from the WRF model for the same period as the SCADA. An equivalent wind speed (wsi) is derived from the combined power and pitch...

  12. Evaluation of the Wind Flow Variability Using Scanning Doppler Lidar Measurements

    Science.gov (United States)

    Sand, S. C.; Pichugina, Y. L.; Brewer, A.

    2016-12-01

    Better understanding of the wind flow variability at the heights of the modern turbines is essential to accurately assess of generated wind power and efficient turbine operations. Nowadays the wind energy industry often utilizes scanning Doppler lidar to measure wind-speed profiles at high spatial and temporal resolution.The study presents wind flow features captured by scanning Doppler lidars during the second Wind Forecast and Improvement Project (WFIP 2) sponsored by the Department of Energy (DOE) and National Oceanic and Atmospheric Administration (NOAA). This 18-month long experiment in the Columbia River Basin aims to improve model wind forecasts complicated by mountain terrain, coastal effects, and numerous wind farms.To provide a comprehensive dataset to use for characterizing and predicting meteorological phenomena important to Wind Energy, NOAA deployed scanning, pulsed Doppler lidars to two sites in Oregon, one at Wasco, located upstream of all wind farms relative to the predominant westerly flow in the region, and one at Arlington, located in the middle of several wind farms.In this presentation we will describe lidar scanning patterns capable of providing data in conical, or vertical-slice modes. These individual scans were processed to obtain 15-min averaged profiles of wind speed and direction in real time. Visualization of these profiles as time-height cross sections allows us to analyze variability of these parameters with height, time and location, and reveal periods of rapid changes (ramp events). Examples of wind flow variability between two sites of lidar measurements along with examples of reduced wind velocity downwind of operating turbines (wakes) will be presented.

  13. Testing measurements of airflow velocity in road tunnels

    Directory of Open Access Journals (Sweden)

    Danišovič Peter

    2017-01-01

    Full Text Available Within the project entitled “Models of formation and spread of fire to increase safety of road tunnels”, it was necessary to devise a method how to record airflow velocity during the fire in situ tests in road tunnels. Project is in first year of its solution so one testing measurement was performed to check the functionality of anemometers selected for this project and the first in situ measurement was also performed just a few days ago.

  14. Doppler Wind Lidar Measurements and Scalability to Space

    Data.gov (United States)

    National Aeronautics and Space Administration — Global measurements of wind speed and direction from Doppler wind lidars, if available, would significantly improve forecasting of severe weather events such as...

  15. AXAOTHER XL -- A spreadsheet for determining doses for incidents caused by tornadoes or high-velocity straight winds

    International Nuclear Information System (INIS)

    Simpkins, A.A.

    1996-09-01

    AXAOTHER XL is an Excel Spreadsheet used to determine dose to the maximally exposed offsite individual during high-velocity straight winds or tornado conditions. Both individual and population doses may be considered. Potential exposure pathways are inhalation and plume shine. For high-velocity straight winds the spreadsheet has the capability to determine the downwind relative air concentration, however for the tornado conditions, the user must enter the relative air concentration. Theoretical models are discussed and hand calculations are performed to ensure proper application of methodologies. A section has also been included that contains user instructions for the spreadsheet

  16. Velocity measurement accuracy in optical microhemodynamics: experiment and simulation

    International Nuclear Information System (INIS)

    Chayer, Boris; Cloutier, Guy; L Pitts, Katie; Fenech, Marianne

    2012-01-01

    Micro particle image velocimetry (µPIV) is a common method to assess flow behavior in blood microvessels in vitro as well as in vivo. The use of red blood cells (RBCs) as tracer particles, as generally considered in vivo, creates a large depth of correlation (DOC), even as large as the vessel itself, which decreases the accuracy of the method. The limitations of µPIV for blood flow measurements based on RBC tracking still have to be evaluated. In this study, in vitro and in silico models were used to understand the effect of the DOC on blood flow measurements using µPIV RBC tracer particles. We therefore employed a µPIV technique to assess blood flow in a 15 µm radius glass tube with a high-speed CMOS camera. The tube was perfused with a sample of 40% hematocrit blood. The flow measured by a cross-correlating speckle tracking technique was compared to the flow rate of the pump. In addition, a three-dimensional mechanical RBC-flow model was used to simulate optical moving speckle at 20% and 40% hematocrits, in 15 and 20 µm radius circular tubes, at different focus planes, flow rates and for various velocity profile shapes. The velocity profiles extracted from the simulated pictures were compared with good agreement with the corresponding velocity profiles implemented in the mechanical model. The flow rates from both the in vitro flow phantom and the mathematical model were accurately measured with less than 10% errors. Simulation results demonstrated that the hematocrit (paired t tests, p = 0.5) and the tube radius (p = 0.1) do not influence the precision of the measured flow rate, whereas the shape of the velocity profile (p < 0.001) and the location of the focus plane (p < 0.001) do, as indicated by measured errors ranging from 3% to 97%. In conclusion, the use of RBCs as tracer particles makes a large DOC and affects the image processing required to estimate the flow velocities. We found that the current µPIV method is acceptable to estimate the flow rate

  17. Velocity-pressure correlation measurements in complex free shear flows

    International Nuclear Information System (INIS)

    Naka, Yoshitsugu; Obi, Shinnosuke

    2009-01-01

    Simultaneous measurements of fluctuating velocity and pressure were performed in various turbulent free shear flows including a turbulent mixing layer and the wing-tip vortex trailing from a NACA0012 half-wing. Two different methods for fluctuating static pressure measurement were considered: a direct method using a miniature Pitot tube and an indirect method where static pressure was calculated from total pressure. The pressure obtained by either of these methods was correlated with the velocity measured by an X-type hot-wire probe. The results from these two techniques agreed with each other in the turbulent mixing layer. In the wing-tip vortex case, however, some discrepancies were found, although overall characteristics of the pressure-related statistics were adequately captured by both methods.

  18. Gas and particle velocity measurements in an induction plasma

    International Nuclear Information System (INIS)

    Lesinski, J.; Gagne, R.; Boulos, M.I.

    1981-08-01

    Laser doppler anemometry was used for the measurements of the plasma and particle velocity profiles in the coil region of an inductively coupled plasma. Results are reported for a 50 mm ID induction torch operated at atmospheric pressure with argon as the plasma gas. The oscillator frequency was 3 MHz and the power in the coil was varied between 4.6 and 10.5 kW. The gas velocity measurements were made using a fine carbon powder as a tracer (dp approx. = 1 μm). Measurements were also made with larger silicon particles (dp = 33 μm and sigma = 13 μm) centrally injected in the plasma under different operating conditions

  19. Spectral characteristics of aurorae connected with high-velocity flows of the solar wind from coronal holes

    International Nuclear Information System (INIS)

    Khviyuzova, T.A.; Leont'ev, S.V.

    1997-01-01

    Bright electron aurorae almost always followed by red lower edge occur when the Earth is being passed by high-velocity flows from coronal holes within the auroral range at the night meridian. In contrast to other types of the solar wind the high-velocity flows from coronal holes do not cause the occurrence of A type red polar aurorae, that is, the spectrum of electrons pouring into the Earth atmosphere in these cases is shifted towards higher energies

  20. A comprehensive measure of the energy resource: Wind power potential (WPP)

    International Nuclear Information System (INIS)

    Zhang, Jie; Chowdhury, Souma; Messac, Achille

    2014-01-01

    Highlights: • A more comprehensive metric is developed to accurately assess the quality of wind resources at a site. • WPP exploits the joint distribution of wind speed and direction, and yields more credible estimates. • WPP investigates the effect of wind distribution on the optimal net power generation of a farm. • The results show that WPD and WPP follow different trends. - Abstract: Currently, the quality of available wind energy at a site is assessed using wind power density (WPD). This paper proposes to use a more comprehensive metric: the wind power potential (WPP). While the former accounts for only wind speed information, the latter exploits the joint distribution of wind speed and wind direction and yields more credible estimates. The WPP investigates the effect of wind velocity distribution on the optimal net power generation of a farm. A joint distribution of wind speed and direction is used to characterize the stochastic variation of wind conditions. Two joint distribution methods are adopted in this paper: bivariate normal distribution and anisotropic lognormal method. The net power generation for a particular farmland size and installed capacity is maximized for different distributions of wind speed and wind direction, using the Unrestricted Wind Farm Layout Optimization (UWFLO) framework. A response surface is constructed to represent the computed maximum wind farm capacity factor as a function of the parameters of the wind distribution. Two different response surface methods are adopted in this paper: (i) the adaptive hybrid functions (AHF), and (ii) the quadratic response surface method (QRSM). Toward this end, for any farm site, we can (i) estimate the parameters of the joint distribution using recorded wind data (for bivariate normal or anisotropic lognormal distributions) and (ii) predict the maximum capacity factor for a specified farm size and capacity using this response surface. The WPP metric is illustrated using recorded wind

  1. Measurement uncertainty budget of an interferometric flow velocity sensor

    Science.gov (United States)

    Bermuske, Mike; Büttner, Lars; Czarske, Jürgen

    2017-06-01

    Flow rate measurements are a common topic for process monitoring in chemical engineering and food industry. To achieve the requested low uncertainties of 0:1% for flow rate measurements, a precise measurement of the shear layers of such flows is necessary. The Laser Doppler Velocimeter (LDV) is an established method for measuring local flow velocities. For exact estimation of the flow rate, the flow profile in the shear layer is of importance. For standard LDV the axial resolution and therefore the number of measurement points in the shear layer is defined by the length of the measurement volume. A decrease of this length is accompanied by a larger fringe distance variation along the measurement axis which results in a rise of the measurement uncertainty for the flow velocity (uncertainty relation between spatial resolution and velocity uncertainty). As a unique advantage, the laser Doppler profile sensor (LDV-PS) overcomes this problem by using two fan-like fringe systems to obtain the position of the measured particles along the measurement axis and therefore achieve a high spatial resolution while it still offers a low velocity uncertainty. With this technique, the flow rate can be estimated with one order of magnitude lower uncertainty, down to 0:05% statistical uncertainty.1 And flow profiles especially in film flows can be measured more accurately. The problem for this technique is, in contrast to laboratory setups where the system is quite stable, that for industrial applications the sensor needs a reliable and robust traceability to the SI units, meter and second. Small deviations in the calibration can, because of the highly position depending calibration function, cause large systematic errors in the measurement result. Therefore, a simple, stable and accurate tool is needed, that can easily be used in industrial surroundings to check or recalibrate the sensor. In this work, different calibration methods are presented and their influences to the

  2. Discharge estimation combining flow routing and occasional measurements of velocity

    Directory of Open Access Journals (Sweden)

    G. Corato

    2011-09-01

    Full Text Available A new procedure is proposed for estimating river discharge hydrographs during flood events, using only water level data at a single gauged site, as well as 1-D shallow water modelling and occasional maximum surface flow velocity measurements. One-dimensional diffusive hydraulic model is used for routing the recorded stage hydrograph in the channel reach considering zero-diffusion downstream boundary condition. Based on synthetic tests concerning a broad prismatic channel, the "suitable" reach length is chosen in order to minimize the effect of the approximated downstream boundary condition on the estimation of the upstream discharge hydrograph. The Manning's roughness coefficient is calibrated by using occasional instantaneous surface velocity measurements during the rising limb of flood that are used to estimate instantaneous discharges by adopting, in the flow area, a two-dimensional velocity distribution model. Several historical events recorded in three gauged sites along the upper Tiber River, wherein reliable rating curves are available, have been used for the validation. The outcomes of the analysis can be summarized as follows: (1 the criterion adopted for selecting the "suitable" channel length based on synthetic test studies has proved to be reliable for field applications to three gauged sites. Indeed, for each event a downstream reach length not more than 500 m is found to be sufficient, for a good performances of the hydraulic model, thereby enabling the drastic reduction of river cross-sections data; (2 the procedure for Manning's roughness coefficient calibration allowed for high performance in discharge estimation just considering the observed water levels and occasional measurements of maximum surface flow velocity during the rising limb of flood. Indeed, errors in the peak discharge magnitude, for the optimal calibration, were found not exceeding 5% for all events observed in the three investigated gauged sections, while the

  3. Sound field separation with sound pressure and particle velocity measurements

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren; Jacobsen, Finn; Leclère, Quentin

    2012-01-01

    separation techniques make it possible to distinguish between outgoing and incoming waves from the two sides, and thus NAH can be applied. In this paper, a separation method based on the measurement of the particle velocity in two layers and another method based on the measurement of the pressure...... and the velocity in a single layer are proposed. The two methods use an equivalent source formulation with separate transfer matrices for the outgoing and incoming waves, so that the sound from the two sides of the array can be modeled independently. A weighting scheme is proposed to account for the distance......In conventional near-field acoustic holography (NAH) it is not possible to distinguish between sound from the two sides of the array, thus, it is a requirement that all the sources are confined to only one side and radiate into a free field. When this requirement cannot be fulfilled, sound field...

  4. Vertical velocity and turbulence aspects during Mistral events as observed by UHF wind profilers

    Directory of Open Access Journals (Sweden)

    J.-L. Caccia

    2004-11-01

    Full Text Available The general purpose of this paper is to experimentally study mesoscale dynamical aspects of the Mistral in the coastal area located at the exit of the Rhône-valley. The Mistral is a northerly low-level flow blowing in southern France along the Rhône-valley axis, located between the French Alps and the Massif Central, towards the Mediterranean Sea. The experimental data are obtained by UHF wind profilers deployed during two major field campaigns, MAP (Mesoscale Alpine Program in autumn 1999, and ESCOMPTE (Expérience sur Site pour COntraindre les Modèles de Pollution atmosphériques et de Transports d'Emission in summer 2001. Thanks to the use of the time evolution of the vertical profile of the horizontal wind vector, recent works have shown that the dynamics of the Mistral is highly dependent on the season because of the occurrence of specific synoptic patterns. In addition, during summer, thermal forcing leads to a combination of sea breeze with Mistral and weaker Mistral due to the enhanced friction while, during autumn, absence of convective turbulence leads to substantial acceleration as low-level jets are generated in the stably stratified planetary boundary layer. At the exit of the Rhône valley, the gap flow dynamics dominates, whereas at the lee of the Alps, the dynamics is driven by the relative contribution of "flow around" and "flow over" mechanisms, upstream of the Alps. This paper analyses vertical velocity and turbulence, i.e. turbulent dissipation rate, with data obtained by the same UHF wind profilers during the same Mistral events. In autumn, the motions are found to be globally and significantly subsident, which is coherent for a dry, cold and stable flow approaching the sea, and the turbulence is found to be of pure dynamical origin (wind shears and mountain/lee wave breaking, which is coherent with non-convective situations. In summer, due to the ground heating and to the interactions with thermal circulation, the

  5. Vertical velocity and turbulence aspects during Mistral events as observed by UHF wind profilers

    Science.gov (United States)

    Caccia, J.; Guénard, V.; Benech, B.; Campistron, B.; Drobinski, P.

    2004-11-01

    The general purpose of this paper is to experimentally study mesoscale dynamical aspects of the Mistral in the coastal area located at the exit of the Rhône-valley. The Mistral is a northerly low-level flow blowing in southern France along the Rhône-valley axis, located between the French Alps and the Massif Central, towards the Mediterranean Sea. The experimental data are obtained by UHF wind profilers deployed during two major field campaigns, MAP (Mesoscale Alpine Program) in autumn 1999, and ESCOMPTE (Expérience sur Site pour COntraindre les Modèles de Pollution atmosphériques et de Transports d'Emission) in summer 2001. Thanks to the use of the time evolution of the vertical profile of the horizontal wind vector, recent works have shown that the dynamics of the Mistral is highly dependent on the season because of the occurrence of specific synoptic patterns. In addition, during summer, thermal forcing leads to a combination of sea breeze with Mistral and weaker Mistral due to the enhanced friction while, during autumn, absence of convective turbulence leads to substantial acceleration as low-level jets are generated in the stably stratified planetary boundary layer. At the exit of the Rhône valley, the gap flow dynamics dominates, whereas at the lee of the Alps, the dynamics is driven by the relative contribution of "flow around" and "flow over" mechanisms, upstream of the Alps. This paper analyses vertical velocity and turbulence, i.e. turbulent dissipation rate, with data obtained by the same UHF wind profilers during the same Mistral events. In autumn, the motions are found to be globally and significantly subsident, which is coherent for a dry, cold and stable flow approaching the sea, and the turbulence is found to be of pure dynamical origin (wind shears and mountain/lee wave breaking), which is coherent with non-convective situations. In summer, due to the ground heating and to the interactions with thermal circulation, the vertical motions are

  6. Vertical velocity and turbulence aspects during Mistral events as observed by UHF wind profilers

    Energy Technology Data Exchange (ETDEWEB)

    Caccia, J.L.; Guenard, V. [LSEET, CNRS/Univ. de Toulon, La Garde (France); Benech, B.; Campistron, B. [CRA/LA, CNRS/Obs. Midi-Pyrenees, Campistrous (France); Drobinski, P. [IPSL/SA, CNRS/Univ. de Paris VI, Paris (France)

    2004-07-01

    The general purpose of this paper is to experimentally study mesoscale dynamical aspects of the Mistral in the coastal area located at the exit of the Rhone-valley. The Mistral is a northerly low-level flow blowing in southern France along the Rhone-valley axis, located between the French Alps and the Massif Central, towards the Mediterranean Sea. The experimental data are obtained by UHF wind profilers deployed during two major field campaigns, MAP (mesoscale alpine program) in autumn 1999, and ESCOMPTE (Experience sur Site pour COntraindre les Modeles de Pollution atmospheriques et de Transports d'Emission) in summer 2001. Thanks to the use of the time evolution of the vertical profile of the horizontal wind vector, recent works have shown that the dynamics of the Mistral is highly dependent on the season because of the occurrence of specific synoptic patterns. In addition, during summer, thermal forcing leads to a combination of sea breeze with Mistral and weaker Mistral due to the enhanced friction while, during autumn, absence of convective turbulence leads to substantial acceleration as low-level jets are generated in the stably stratified planetary boundary layer. At the exit of the Rhone valley, the gap flow dynamics dominates, whereas at the lee of the Alps, the dynamics is driven by the relative contribution of ''flow around'' and ''flow over'' mechanisms, upstream of the Alps. This paper analyses vertical velocity and turbulence, i.e. turbulent dissipation rate, with data obtained by the same UHF wind profilers during the same Mistral events. In autumn, the motions are found to be globally and significantly subsident, which is coherent for a dry, cold and stable flow approaching the sea, and the turbulence is found to be of pure dynamical origin (wind shears and mountain/lee wave breaking), which is coherent with non-convective situations. In summer, due to the ground heating and to the interactions with

  7. Velocity ratio measurement using the frequency of gyro backward wave

    International Nuclear Information System (INIS)

    Muggli, P.; Tran, M.Q.; Tran, T.M.

    1990-10-01

    The operating diagram of a low quality factor, 8GHz TE 01 0 gyrotron exhibits oscillations between 6.8 and 7.3GHz. These oscillations are identified as the backward wave component of the TE 21 0 traveling mode. As the resonance condition of this mode depends on the average parallel velocity [ > of the beam electrons (ω BW ≅Ω C /γ - k [ [ >), the measurement of ω BW for given Ω C and γ, is used as a diagnostic for the beam electrons velocity ratio α= / [ >. The values of α, deduced from ω BW through the linear dispersion relation for the electron cyclotron instability in an infinite waveguide, are unrealistic. A non-linear simulation code gives α values which are in very good agreement with the ones predicted by a particle trajectory code (+10% to +20%). We find numerically that the particles' velocity dispersion in vperpendicular and v [ increases ω BW . This effect explains part of the discrepancy between the values of α inferred from ω BW without velocity dispersion and the expected values. (author) 10 refs., 6 figs., 1 tab

  8. Measurements of phoretic velocities of aerosol particles in microgravity conditions

    Science.gov (United States)

    Prodi, F.; Santachiara, G.; Travaini, S.; Vedernikov, A.; Dubois, F.; Minetti, C.; Legros, J. C.

    2006-11-01

    Measurements of thermo- and diffusio-phoretic velocities of aerosol particles (carnauba wax, paraffin and sodium chloride) were performed in microgravity conditions (Drop Tower facility, in Bremen, and Parabolic Flights, in Bordeaux). In the case of thermophoresis, a temperature gradient was obtained by heating the upper plate of the cell, while the lower one was maintained at environmental temperature. For diffusiophoresis, the water vapour gradient was obtained with sintered plates imbued with a water solution of MgCl 2 and distilled water, at the top and at the bottom of the cell, respectively. Aerosol particles were observed through a digital holographic velocimeter, a device allowing the determination of 3-D coordinates of particles from the observed volume. Particle trajectories and consequently particle velocities were reconstructed through the analysis of the sequence of particle positions. The experimental values of reduced thermophoretic velocities are between the theoretical values of Yamamoto and Ishihara [Yamamoto, K., Ishihara, Y., 1988. Thermophoresis of a spherical particle in a rarefied gas of a transition regime. Phys. Fluids. 31, 3618-3624] and Talbot et al. [Talbot, L., Cheng, R.K., Schefer, R.W., Willis, D.R., 1980. Thermophoresis of particles in a heated boundary layer. J. Fluid Mech. 101, 737-758], and do not show a clear dependence on the thermal conductivity of the aerosol. The existence of negative thermophoresis is not confirmed in our experiments. Concerning diffusiophoretic experiments, the results obtained show a small increase of reduced diffusiophoretic velocity with the Knudsen number.

  9. LDV measurement of boundary layer on rotating blade surface in wind tunnel

    Science.gov (United States)

    Maeda, Takao; Kamada, Yasunari; Murata, Junsuke; Suzuki, Daiki; Kaga, Norimitsu; Kagisaki, Yosuke

    2014-12-01

    Wind turbines generate electricity due to extracting energy from the wind. The rotor aerodynamics strongly depends on the flow around blade. The surface flow on the rotating blade affects the sectional performance. The wind turbine surface flow has span-wise component due to span-wise change of airfoil section, chord length, twisted angle of blade and centrifugal force on the flow. These span-wise flow changes the boundary layer on the rotating blade and the sectional performance. Hence, the thorough understanding of blade surface flow is important to improve the rotor performance. For the purpose of clarification of the flow behaviour around the rotor blade, the velocity in the boundary layer on rotating blade surface of an experimental HAWT was measured in a wind tunnel. The velocity measurement on the blade surface was carried out by a laser Doppler velocimeter (LDV). As the results of the measurement, characteristics of surface flow are clarified. In optimum tip speed operation, the surface flow on leading edge and r/R=0.3 have large span-wise velocity which reaches 20% of sectional inflow velocity. The surface flow inboard have three dimensional flow patterns. On the other hand, the flow outboard is almost two dimensional in cross sectional plane.

  10. Stereo particle image velocimetry set up for measurements in the wake of scaled wind turbines

    Science.gov (United States)

    Campanardi, Gabriele; Grassi, Donato; Zanotti, Alex; Nanos, Emmanouil M.; Campagnolo, Filippo; Croce, Alessandro; Bottasso, Carlo L.

    2017-08-01

    Stereo particle image velocimetry measurements were carried out in the boundary layer test section of Politecnico di Milano large wind tunnel to survey the wake of a scaled wind turbine model designed and developed by Technische Universität München. The stereo PIV instrumentation was set up to survey the three velocity components on cross-flow planes at different longitudinal locations. The area of investigation covered the entire extent of the wind turbines wake that was scanned by the use of two separate traversing systems for both the laser and the cameras. Such instrumentation set up enabled to gain rapidly high quality results suitable to characterise the behaviour of the flow field in the wake of the scaled wind turbine. This would be very useful for the evaluation of the performance of wind farm control methodologies based on wake redirection and for the validation of CFD tools.

  11. Model-assisted measurements of suspension-feeding flow velocities.

    Science.gov (United States)

    Du Clos, Kevin T; Jones, Ian T; Carrier, Tyler J; Brady, Damian C; Jumars, Peter A

    2017-06-01

    Benthic marine suspension feeders provide an important link between benthic and pelagic ecosystems. The strength of this link is determined by suspension-feeding rates. Many studies have measured suspension-feeding rates using indirect clearance-rate methods, which are based on the depletion of suspended particles. Direct methods that measure the flow of water itself are less common, but they can be more broadly applied because, unlike indirect methods, direct methods are not affected by properties of the cleared particles. We present pumping rates for three species of suspension feeders, the clams Mya arenaria and Mercenaria mercenaria and the tunicate Ciona intestinalis , measured using a direct method based on particle image velocimetry (PIV). Past uses of PIV in suspension-feeding studies have been limited by strong laser reflections that interfere with velocity measurements proximate to the siphon. We used a new approach based on fitting PIV-based velocity profile measurements to theoretical profiles from computational fluid dynamic (CFD) models, which allowed us to calculate inhalant siphon Reynolds numbers ( Re ). We used these inhalant Re and measurements of siphon diameters to calculate exhalant Re , pumping rates, and mean inlet and outlet velocities. For the three species studied, inhalant Re ranged from 8 to 520, and exhalant Re ranged from 15 to 1073. Volumetric pumping rates ranged from 1.7 to 7.4 l h -1 for M . arenaria , 0.3 to 3.6 l h -1 for M . m ercenaria and 0.07 to 0.97 l h -1 for C . intestinalis We also used CFD models based on measured pumping rates to calculate capture regions, which reveal the spatial extent of pumped water. Combining PIV data with CFD models may be a valuable approach for future suspension-feeding studies. © 2017. Published by The Company of Biologists Ltd.

  12. Velocity distribution measurement in wire-spaced fuel pin bundle

    International Nuclear Information System (INIS)

    Mizuta, Hiroshi; Ohtake, Toshihide; Uruwashi, Shinichi; Takahashi, Keiichi

    1974-01-01

    Flow distribution measurement was made in the subchannels of a pin bundle in air flow. The present paper is interim because the target of this work is the decision of temperature of the pin surface in contact with wire spacers. The wire-spaced fuel pin bundle used for the experiment consists of 37 simulated fuel pins of stainless steel tubes, 3000 mm in length and 31.6 mm in diameter, which are wound spirally with 6 mm stainless steel wire. The bundle is wrapped with a hexagonal tube, 3500 mm in length and 293 mm in flat-to-flat distance. The bundle is fixed with knock-bar at the entrance of air flow in the hexagonal tube. The pitch of pins in the bundle is 37.6 mm (P/D=1.19) and the wrapping pitch of wire is 1100 mm (H/D=34.8). A pair of arrow-type 5-hole Pitot tubes are used to measure the flow velocity and the direction of air flow in the pin bundle. The measurement of flow distribution was made with the conditions of air flow rate of 0.33 m 3 /sec, air temperature of 45 0 C, and average Reynolds number of 15100 (average air velocity of 20.6 m/sec.). It was found that circular flow existed in the down stream of wire spacers, that axial flow velocity was slower in the subchannels, which contained wire spacers, than in those not affected by the wire, and that the flow angle to the axial velocity at the boundary of subchannels was two thirds smaller than wire wrapping angle. (Tai, I.)

  13. EnKF OSSE Experiments Assessing the Impact of HIRAD Wind Speed and HIWRAP Radial Velocity Data on Analysis of Hurricane Karl (2010)

    Science.gov (United States)

    Albers, Cerese; Sippel, Jason A.; Braun, Scott A.; Miller, Timothy

    2012-01-01

    Previous studies (e.g., Zhang et al. 2009, Weng et al. 2011) have shown that radial velocity data from airborne and ground-based radars can be assimilated into ensemble Kalman filter (EnKF) systems to produce accurate analyses of tropical cyclone vortices, which can reduce forecast intensity error. Recently, wind speed data from SFMR technology has also been assimilated into the same types of systems and has been shown to improve the forecast intensity of mature tropical cyclones. Two instruments that measure these properties were present during the NASA Genesis and Rapid Intensification Processes (GRIP) field experiment in 2010 which sampled Hurricane Karl, and will next be co-located on the same aircraft for the subsequent NASA HS3 experiment. The High Altitude Wind and Rain Profiling Radar (HIWRAP) is a conically scanning Doppler radar mounted upon NASAs Global Hawk unmanned aerial vehicle, and the usefulness of its radial velocity data for assimilation has not been previously examined. Since the radar scans from above with a fairly large fixed elevation angle, it observes a large component of the vertical wind, which could degrade EnKF analyses compared to analyses with data taken from lesser elevation angles. The NASA Hurricane Imaging Radiometer (HIRAD) is a passive microwave radiometer similar to SFMR, and measures emissivity and retrieves hurricane surface wind speeds and rain rates over a much wider swath. Thus, this study examines the impact of assimilating simulated HIWRAP radial velocity data into an EnKF system, simulated HIRAD wind speed, and HIWRAP+HIRAD with the Weather Research and Forecasting (WRF) model and compares the results to no data assimilation and also to the Truth from which the data was simulated for both instruments.

  14. Wind potential data analysis based on on-site measurements with tall meteorological masts installed in northern Bulgaria

    International Nuclear Information System (INIS)

    Terziev, A.; Genovski, I.; Petrov, P.; Valchev, V.

    2010-01-01

    The current work has studied the possibility of correlation between wind data collected with tall meteorological masts in Northern Bulgaria. The processed data were collected for the same time period. The analysis is based on daily wind data. The correlation was made taking into consideration the following factors: the height of carried wind measurements, the prevailing wind direction, and the surface roughness of the relief. The analysis of the distance effect between meteorological masts is also considered. The possibility of modeling the wind velocity field for the area limited by the meteorological mast locations is examined. For this purpose for wind speed velocity field description is used triangulation with linear interpolation between the data. Data interpolation was made based on compulsory condition for relative flatness of the terrain. (authors)

  15. Measured and modeled dry deposition velocities over the ESCOMPTE area

    Science.gov (United States)

    Michou, M.; Laville, P.; Serça, D.; Fotiadi, A.; Bouchou, P.; Peuch, V.-H.

    2005-03-01

    Measurements of the dry deposition velocity of ozone have been made by the eddy correlation method during ESCOMPTE (Etude sur Site pour COntraindre les Modèles de Pollution atmosphérique et de Transport d'Emissions). The strong local variability of natural ecosystems was sampled over several weeks in May, June and July 2001 for four sites with varying surface characteristics. The sites included a maize field, a Mediterranean forest, a Mediterranean shrub-land, and an almost bare soil. Measurements of nitrogen oxide deposition fluxes by the relaxed eddy correlation method have also been carried out at the same bare soil site. An evaluation of the deposition velocities computed by the surface module of the multi-scale Chemistry and Transport Model MOCAGE is presented. This module relies on a resistance approach, with a detailed treatment of the stomatal contribution to the surface resistance. Simulations at the finest model horizontal resolution (around 10 km) are compared to observations. If the seasonal variations are in agreement with the literature, comparisons between raw model outputs and observations, at the different measurement sites and for the specific observing periods, are contrasted. As the simulated meteorology at the scale of 10 km nicely captures the observed situations, the default set of surface characteristics (averaged at the resolution of a grid cell) appears to be one of the main reasons for the discrepancies found with observations. For each case, sensitivity studies have been performed in order to see the impact of adjusting the surface characteristics to the observed ones, when available. Generally, a correct agreement with the observations of deposition velocities is obtained. This advocates for a sub-grid scale representation of surface characteristics for the simulation of dry deposition velocities over such a complex area. Two other aspects appear in the discussion. Firstly, the strong influence of the soil water content to the plant

  16. 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

  17. On the energy pattern factor in wind measurements

    Energy Technology Data Exchange (ETDEWEB)

    Buick, T R; Doherty, M A; McMullan, J.T., Morgan, R.; Murray, R B

    1977-01-01

    Measurements of energy pattern factor K/sub e/ were made using a continuous-analogue wind-power metering technique, rather than by the more usual sampling procedure. The values obtained were significantly larger than the usually accepted figure. The discrepancy is attributed partly to the method of measurement, which includes the actual power present rather than the amount that can be extracted, and partly to the use of rather more typical wind speeds. It is concluded, however, that more energy can be derived from wind schemes than was thought, even during periods of light wind. These conclusions improve the viability of wind power plants.

  18. Velocity field measurements on high-frequency, supersonic microactuators

    Science.gov (United States)

    Kreth, Phillip A.; Ali, Mohd Y.; Fernandez, Erik J.; Alvi, Farrukh S.

    2016-05-01

    The resonance-enhanced microjet actuator which was developed at the Advanced Aero-Propulsion Laboratory at Florida State University is a fluidic-based device that produces pulsed, supersonic microjets by utilizing a number of microscale, flow-acoustic resonance phenomena. The microactuator used in this study consists of an underexpanded source jet that flows into a cylindrical cavity with a single, 1-mm-diameter exhaust orifice through which an unsteady, supersonic jet issues at a resonant frequency of 7 kHz. The flowfields of a 1-mm underexpanded free jet and the microactuator are studied in detail using high-magnification, phase-locked flow visualizations (microschlieren) and two-component particle image velocimetry. These are the first direct measurements of the velocity fields produced by such actuators. Comparisons are made between the flow visualizations and the velocity field measurements. The results clearly show that the microactuator produces pulsed, supersonic jets with velocities exceeding 400 m/s for roughly 60 % of their cycles. With high unsteady momentum output, this type of microactuator has potential in a range of ow control applications.

  19. Velocity field measurement in micro-bubble emission boiling

    International Nuclear Information System (INIS)

    Ito, Daisuke; Saito, Yasushi; Natazuka, Jun

    2017-01-01

    Liquid inlet behavior to a heat surface in micro-bubble emission boiling (MEB) was investigated by flow measurement using particle image velocimetry (PIV). Subcooled pool boiling experiments under atmospheric pressure were carried out using a heat surface with a diameter of 10 mm. An upper end of a heater block made of copper was used as the heat surface. Working fluid was the deionized water and the subcooling was varied from 40 K to 70 K. Three K-type thermocouples were installed in the copper block to measure the temperature gradient, and the heat flux and wall superheat were estimated from these temperature data to make a boiling curve. The flow visualization around the heat surface was carried out using a high-speed video camera and a light sheet. The microbubbles generated in the MEB were used as tracer particles and the velocity field was obtained by PIV analysis of the acquired image sequence. As a result, the higher heat fluxes than the critical heat flux could be obtained in the MEB region. In addition, the distribution characteristics of the velocity in MEB region were studied using the PIV results and the location of the stagnation point in the velocity fields was discussed. (author)

  20. Wind Atlas for South Africa (WASA). Report on Measurements

    DEFF Research Database (Denmark)

    Mabille, Eugéne; Prinsloo, Eric; Mortensen, Niels Gylling

    , to verify the results of the meso-scale modelling. The Measurements work package (WP2) is one of six work packages that collectively make up the Wind Atlas for South Africa (WASA) project. The measurements also provide observed wind climates at the measurement sites, which can be used by micrositing...... to be commissioned was WM06 (Sutherland) and this was completed on 17 September 2010. The outputs of WP2 are: i. Establish 10 high quality wind measurement stations providing three years of measurement data for calibration of the mesoscale modelling. ii. A database system for wind data collection and on-line Web...

  1. Predicted and measured velocity distribution in a model heat exchanger

    International Nuclear Information System (INIS)

    Rhodes, D.B.; Carlucci, L.N.

    1984-01-01

    This paper presents a comparison between numerical predictions, using the porous media concept, and measurements of the two-dimensional isothermal shell-side velocity distributions in a model heat exchanger. Computations and measurements were done with and without tubes present in the model. The effect of tube-to-baffle leakage was also investigated. The comparison was made to validate certain porous media concepts used in a computer code being developed to predict the detailed shell-side flow in a wide range of shell-and-tube heat exchanger geometries

  2. Regional Analysis of Long-term Local and Synoptic Effects on Wind Velocity and Energy Patterns in Complex Terrain

    Science.gov (United States)

    Belu, R.; Koracin, D. R.

    2017-12-01

    Investments in renewable energy are justified in both environmental and economic terms. Climate change risks call for mitigation strategies aimed to reduce pollutant emissions, while the energy supply is facing high uncertainty by the current or future global economic and political contexts. Wind energy is playing a strategic role in the efforts of any country for sustainable development and energy supply security. Wind energy is a weather and climate-dependent resource, having a natural spatio-temporal variability at time scales ranging from fraction of seconds to seasons and years, while at spatial scales is strongly affected by the topography and vegetation. Main objective of the study is to investigate spatio-temporal characteristics of the wind velocity in the Southwest U.S., that are relevant to wind energy assessment, analysis, development, operation, and grid integration, by using long-term multiple meteorological tower observations. Wind velocity data and other meteorological parameters from five towers, located near Tonopah, Nevada, operated between 2003 to 2008, and from three towers are located in Carson Valley, Nevada, operated between 2006 and 2014 were used in this study. Multi-annual wind speed data collected did not show significant increase trends with increasing elevation; the differences are mainly governed by the topographic complexity, including local atmospheric circulations. Auto- and cross-correlations show a strong coherence between the wind speed and direction with slowly decreasing amplitude of the multi-day periodicity with increasing lag periods. Besides pronounced diurnal periodicity at all locations, detrended fluctuation analysis also showed significant seasonal and annual periodicities, and long-memory persistence with similar characteristics. In spite of significant differences in mean wind speeds among the towers, due to location specifics, the relatively high auto- and cross-correlation coefficients among the towers indicate

  3. On mean wind and turbulence profile measurements from ground-based wind lidars

    DEFF Research Database (Denmark)

    Mikkelsen, Torben

    2009-01-01

    Two types of wind lidar?s have become available for ground-based vertical mean wind and turbulence profiling. A continuous wave (CW) wind lidar, and a pulsed wind lidar. Although they both are build upon the same recent 1.55 μ telecom fibre technology, they possess fundamental differences between...... their temporal and spatial resolution capabilities. A literature review of the two lidar systems spatial and temporal resolution characteristics will be presented, and the implication for the two lidar types vertical profile measurements of mean wind and turbulence in the lower atmospheric boundary layer...

  4. Particle Image Velocimetry (PIV) Measurements of Suspension-Feeding Velocities

    Science.gov (United States)

    Du Clos, K.; Jones, I. T.; Carrier, T. J.; Jumars, P. A.

    2016-02-01

    Active suspension feeders, such as bivalves and tunicates, connect benthic and pelagic ecosystems by packaging suspended matter into larger fecal and pseudofecal particles, greatly enhancing the flux of carbon and nutrients from the water column to the benthos. The volume of water processed by a population of suspension feeders is commonly estimated by scaling up results from experiments that measure the clearance rate (the volume of water cleared of particles per time) of one or a few individual suspension feeders. Clearance rates vary, however, between species, within a species, and over time for a single individual; and the velocity fields produced by suspension feeders are likely to interact in complex ways. We measured the water velocity fields produced by two species of bivalve, Mya arenaria and Mercenaria mercenaria, and the tunicate Ciona intestinalis, using particle image velocimetry (PIV). We used these measurements to calculate flow rates and Reynolds numbers of inhalant and exhalant siphons. We also observed strong entrainment of water by M. arenaria's exhalant siphon jet that may help to explain how the clam avoids depleting the water around it of particles and oxygen as it feeds. We are using these measurements to inform computational fluid mechanics (CFD) models of suspension feeding, allowing us to examine the interactions of flow fields produced by multiple suspension feeders and other effects not quantified by clearance-rate measurements.

  5. A PRACTICAL APPROACH TO THE GROUND OSCILLATION VELOCITY MEASUREMENT METHOD

    Directory of Open Access Journals (Sweden)

    Siniša Stanković

    2017-01-01

    Full Text Available The use of an explosive’s energy during blasting includes undesired effects on the environment. The seismic influence of a blast, as a major undesired effect, is determined by many national standards, recommendations and calculations where the main parameter is ground oscillation velocity at the field measurement location. There are a few approaches and methods for calculation of expected ground oscillation velocities according to charge weight per delay and the distance from the blast to the point of interest. Utilizations of these methods and formulas do not provide satisfactory results, thus the measured values on diverse distance from the blast field more or less differ from values given by previous calculations. Since blasting works are executed in diverse geological conditions, the aim of this research is the development of a practical and reliable approach which will give a different model for each construction site where blasting works have been or will be executed. The approach is based on a greater number of measuring points in line from the blast field at predetermined distances. This new approach has been compared with other generally used methods and formulas through the use of measurements taken during research along with measurements from several previously executed projects. The results confirmed that the suggested model gives more accurate values.

  6. 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...

  7. Generation of electricity by wind power

    Energy Technology Data Exchange (ETDEWEB)

    Golding, E W

    1976-01-01

    Information on wind power is presented concerning the history of windmills; estimation of the energy obtainable from the wind; wind characteristics and distribution; wind power sites; wind surveys; wind flow over hills; measurement of wind velocity; wind structure and its determination; wind data and energy estimation; testing of wind driven ac generators; wind-driven machines; propeller type windmills; plants for isolated premises and small communities; economy of wind power generation; construction costs for large wind-driven generators; relationship of wind power to other power sources; research and development; and international cooperation.

  8. Wind Speed Preview Measurement and Estimation for Feedforward Control of Wind Turbines

    Science.gov (United States)

    Simley, Eric J.

    Wind turbines typically rely on feedback controllers to maximize power capture in below-rated conditions and regulate rotor speed during above-rated operation. However, measurements of the approaching wind provided by Light Detection and Ranging (lidar) can be used as part of a preview-based, or feedforward, control system in order to improve rotor speed regulation and reduce structural loads. But the effectiveness of preview-based control depends on how accurately lidar can measure the wind that will interact with the turbine. In this thesis, lidar measurement error is determined using a statistical frequency-domain wind field model including wind evolution, or the change in turbulent wind speeds between the time they are measured and when they reach the turbine. Parameters of the National Renewable Energy Laboratory (NREL) 5-MW reference turbine model are used to determine measurement error for a hub-mounted circularly-scanning lidar scenario, based on commercially-available technology, designed to estimate rotor effective uniform and shear wind speed components. By combining the wind field model, lidar model, and turbine parameters, the optimal lidar scan radius and preview distance that yield the minimum mean square measurement error, as well as the resulting minimum achievable error, are found for a variety of wind conditions. With optimized scan scenarios, it is found that relatively low measurement error can be achieved, but the attainable measurement error largely depends on the wind conditions. In addition, the impact of the induction zone, the region upstream of the turbine where the approaching wind speeds are reduced, as well as turbine yaw error on measurement quality is analyzed. In order to minimize the mean square measurement error, an optimal measurement prefilter is employed, which depends on statistics of the correlation between the preview measurements and the wind that interacts with the turbine. However, because the wind speeds encountered by

  9. Field campaign for the comparison of SOUSY radar wind measurements with rawinsonde and model data

    Directory of Open Access Journals (Sweden)

    H. Steinhagen

    Full Text Available A field campaign was carried out from 26 October to 7 November 1992, using the SOUSY-VHF radar and a mobile rawinsonde system installed and operated nearby to produce vertical wind profiles. The purpose of this campaign was to compare the two types of wind measurements with one another and with results from forecast models. Numerical algorithms were developed and applied to the radar data in order to eliminate random errors, correct for velocity aliasing, and calculate the effective zenith angle of the off-vertical beams. Differences between wind profiler data and rawinsonde or model results depend not only upon the errors of the different systems, but also on temporal and spatial variations of the wind field. Therefore, methods for the comparison of radar and rawinsonde data were developed which take into consideration these variations. The practical potential of these methods is demonstrated by comparisons of rawinsonde and radar wind profiles. The comparison of radar data and model output shows excellent agreement in the direction and in the speed of the wind at virtually all altitudes. An evaluation of the quality of wind profiler measurements is possible using the estimation of variance and variability of wind components.

  10. Field campaign for the comparison of SOUSY radar wind measurements with rawinsonde and model data

    Directory of Open Access Journals (Sweden)

    H. Steinhagen

    1994-07-01

    Full Text Available A field campaign was carried out from 26 October to 7 November 1992, using the SOUSY-VHF radar and a mobile rawinsonde system installed and operated nearby to produce vertical wind profiles. The purpose of this campaign was to compare the two types of wind measurements with one another and with results from forecast models. Numerical algorithms were developed and applied to the radar data in order to eliminate random errors, correct for velocity aliasing, and calculate the effective zenith angle of the off-vertical beams. Differences between wind profiler data and rawinsonde or model results depend not only upon the errors of the different systems, but also on temporal and spatial variations of the wind field. Therefore, methods for the comparison of radar and rawinsonde data were developed which take into consideration these variations. The practical potential of these methods is demonstrated by comparisons of rawinsonde and radar wind profiles. The comparison of radar data and model output shows excellent agreement in the direction and in the speed of the wind at virtually all altitudes. An evaluation of the quality of wind profiler measurements is possible using the estimation of variance and variability of wind components.

  11. Comparison of measured and simulated friction velocity and threshold friction velocity using SWEEP

    Science.gov (United States)

    The Wind Erosion Prediction System (WEPS) was developed by the USDA Agricultural Research Service as a tool to predict wind erosion and assess the influence of control practices on windblown soil loss. Occasional failure of the WEPS erosion submodel (SWEEP) to simulate erosion in the Columbia Platea...

  12. Standards for measurements and testing of wind turbine power quality

    Energy Technology Data Exchange (ETDEWEB)

    Soerensen, P [Risoe National Lab., Roskilde (Denmark); Gerdes, G; Klosse, R; Santjer, F [DEWI, Wilhelmshaven (Germany); Robertson, N; Davy, W [NEL, Glasgow (United Kingdom); Koulouvari, M; Morfiadakis, E [CRES, Pikermi (Greece); Larsson, Aa [Chalmers Univ. of Technology, Goeteborg (Sweden)

    1999-03-01

    The present paper describes the work done in power quality sub-task of the project `European Wind Turbine Testing Procedure Developments` funded by the EU SMT program. The objective of the power quality sub-task has been to make analyses and new recommendation(s) for the standardisation of measurement and verification of wind turbine power quality. The work has been organised in three major activities. The first activity has been to propose measurement procedures and to verify existing and new measurement procedures. This activity has also involved a comparison of the measurements and data processing of the participating partners. The second activity has been to investigate the influence of terrain, grid properties and wind farm summation on the power quality of wind turbines with constant rotor speed. The third activity has been to investigate the influence of terrain, grid properties and wind farm summation on the power quality of wind turbines with variable rotor speed. (au)

  13. Pressure drop ana velocity measurements in KMRR fuel rod bundles

    International Nuclear Information System (INIS)

    Yagn, Sun Kyu; Chung, Heung June; Chung, Chang Whan; Chun, Se Young; Song, Chul Wha; Won, Soon Yeun; Chung, Moon Ki

    1990-01-01

    The detailed hydraulic characteristic measurements in subchannels of longitudinally finned rod bundles using one-component LDV(Laser Doppler Velocimeter) were performed. Time mean axial velocity, turbulent intensity, and turbulent micro scales, such as time auto-correlation, Eulerian integral and micro scale, Kolmogorov length and time scale, and Taylor micro length scale were measured. The signals from LDV are inherently more or less discontinuous. The spectra of signals having such intermittent defects can be obtained by the fast Fourier transformation (FFT) of the auto-correlation function. The turbulent crossflow mixing rate between neighboring subchannels and dominant frequencies were evaluated from the measured data. Pressure drop data were obtained for the typical 36-element and 18-element fuel rod bundles fabricated by the design requirement of KMRR fuel and for other type of fuels assembled with 6-fin rods to investigate the fin effects on the pressure drop characteristics

  14. Mapping the solar wind HI outflow velocity in the inner heliosphere by coronagraphic ultraviolet and visible-light observations

    Science.gov (United States)

    Dolei, S.; Susino, R.; Sasso, C.; Bemporad, A.; Andretta, V.; Spadaro, D.; Ventura, R.; Antonucci, E.; Abbo, L.; Da Deppo, V.; Fineschi, S.; Focardi, M.; Frassetto, F.; Giordano, S.; Landini, F.; Naletto, G.; Nicolini, G.; Nicolosi, P.; Pancrazzi, M.; Romoli, M.; Telloni, D.

    2018-05-01

    We investigated the capability of mapping the solar wind outflow velocity of neutral hydrogen atoms by using synergistic visible-light and ultraviolet observations. We used polarised brightness images acquired by the LASCO/SOHO and Mk3/MLSO coronagraphs, and synoptic Lyα line observations of the UVCS/SOHO spectrometer to obtain daily maps of solar wind H I outflow velocity between 1.5 and 4.0 R⊙ on the SOHO plane of the sky during a complete solar rotation (from 1997 June 1 to 1997 June 28). The 28-days data sequence allows us to construct coronal off-limb Carrington maps of the resulting velocities at different heliocentric distances to investigate the space and time evolution of the outflowing solar plasma. In addition, we performed a parameter space exploration in order to study the dependence of the derived outflow velocities on the physical quantities characterising the Lyα emitting process in the corona. Our results are important in anticipation of the future science with the Metis instrument, selected to be part of the Solar Orbiter scientific payload. It was conceived to carry out near-sun coronagraphy, performing for the first time simultaneous imaging in polarised visible-light and ultraviolet H I Lyα line, so providing an unprecedented view of the solar wind acceleration region in the inner corona. The movie (see Sect. 4.2) is available at https://www.aanda.org

  15. Vertical velocity and turbulence aspects during Mistral events as observed by UHF wind profilers

    Directory of Open Access Journals (Sweden)

    J.-L. Caccia

    2004-11-01

    Full Text Available The general purpose of this paper is to experimentally study mesoscale dynamical aspects of the Mistral in the coastal area located at the exit of the Rhône-valley. The Mistral is a northerly low-level flow blowing in southern France along the Rhône-valley axis, located between the French Alps and the Massif Central, towards the Mediterranean Sea. The experimental data are obtained by UHF wind profilers deployed during two major field campaigns, MAP (Mesoscale Alpine Program in autumn 1999, and ESCOMPTE (Expérience sur Site pour COntraindre les Modèles de Pollution atmosphériques et de Transports d'Emission in summer 2001.

    Thanks to the use of the time evolution of the vertical profile of the horizontal wind vector, recent works have shown that the dynamics of the Mistral is highly dependent on the season because of the occurrence of specific synoptic patterns. In addition, during summer, thermal forcing leads to a combination of sea breeze with Mistral and weaker Mistral due to the enhanced friction while, during autumn, absence of convective turbulence leads to substantial acceleration as low-level jets are generated in the stably stratified planetary boundary layer. At the exit of the Rhône valley, the gap flow dynamics dominates, whereas at the lee of the Alps, the dynamics is driven by the relative contribution of "flow around" and "flow over" mechanisms, upstream of the Alps. This paper analyses vertical velocity and turbulence, i.e. turbulent dissipation rate, with data obtained by the same UHF wind profilers during the same Mistral events.

    In autumn, the motions are found to be globally and significantly subsident, which is coherent for a dry, cold and stable flow approaching the sea, and the turbulence is found to be of pure dynamical origin (wind shears and mountain/lee wave breaking, which is coherent with non-convective situations.

    Influence of the tilting reflection mirror on the temperature and wind velocity retrieved by a polarizing atmospheric Michelson interferometer.

    Science.gov (United States)

    Zhang, Chunmin; Li, Ying

    2012-09-20

    The principles of a polarizing atmospheric Michelson interferometer are outlined. The tilt of its reflection mirror results in deflection of the reflected beam and affects the intensities of the observed inteferogram. This effect is systematically analyzed. Both rectangular and circular apertures are considered. The theoretical expression of the modulation depth and phase of the interferogram are derived. These parameters vary with the inclination angle of the mirror and the distance between the deflection center and the optical axis and significantly influence the retrieved temperature and wind speed. If the wind and temperature errors are required to be less than 3 m/s and 5 K, the deflection angle must be less than 0.5°. The errors are also dependent on the shape of aperture. If the reflection mirror is deflected in one direction, the temperature error is smaller for a circular aperture (1.3 K) than for a rectangular one (2.6 K), but the wind velocity errors are almost the same (less than 3 m/s). If the deflection center and incident light beam are coincident, the temperature errors are 3 × 10(-4) K and 0.45 K for circular and rectangular apertures, respectively. The wind velocity errors are 1.2 × 10(-3) m/s and 0.06 m/s. Both are small. The result would be helpful for theoretical research and development of the static polarization wind imaging interferometer.

  16. Using eddy covariance to measure the dependence of air-sea CO2 exchange rate on friction velocity

    Science.gov (United States)

    Landwehr, Sebastian; Miller, Scott D.; Smith, Murray J.; Bell, Thomas G.; Saltzman, Eric S.; Ward, Brian

    2018-03-01

    Parameterisation of the air-sea gas transfer velocity of CO2 and other trace gases under open-ocean conditions has been a focus of air-sea interaction research and is required for accurately determining ocean carbon uptake. Ships are the most widely used platform for air-sea flux measurements but the quality of the data can be compromised by airflow distortion and sensor cross-sensitivity effects. Recent improvements in the understanding of these effects have led to enhanced corrections to the shipboard eddy covariance (EC) measurements.Here, we present a revised analysis of eddy covariance measurements of air-sea CO2 and momentum fluxes from the Southern Ocean Surface Ocean Aerosol Production (SOAP) study. We show that it is possible to significantly reduce the scatter in the EC data and achieve consistency between measurements taken on station and with the ship underway. The gas transfer velocities from the EC measurements correlate better with the EC friction velocity (u*) than with mean wind speeds derived from shipboard measurements corrected with an airflow distortion model. For the observed range of wind speeds (u10 N = 3-23 m s-1), the transfer velocities can be parameterised with a linear fit to u*. The SOAP data are compared to previous gas transfer parameterisations using u10 N computed from the EC friction velocity with the drag coefficient from the Coupled Ocean-Atmosphere Response Experiment (COARE) model version 3.5. The SOAP results are consistent with previous gas transfer studies, but at high wind speeds they do not support the sharp increase in gas transfer associated with bubble-mediated transfer predicted by physically based models.

  17. All-Fiber Airborne Coherent Doppler Lidar to Measure Wind Profiles

    Directory of Open Access Journals (Sweden)

    Liu Jiqiao

    2016-01-01

    Full Text Available An all-fiber airborne pulsed coherent Doppler lidar (CDL prototype at 1.54μm is developed to measure wind profiles in the lower troposphere layer. The all-fiber single frequency pulsed laser is operated with pulse energy of 300μJ, pulse width of 400ns and pulse repetition rate of 10kHz. To the best of our knowledge, it is the highest pulse energy of all-fiber eye-safe single frequency laser that is used in airborne coherent wind lidar. The telescope optical diameter of monostatic lidar is 100 mm. Velocity-Azimuth-Display (VAD scanning is implemented with 20 degrees elevation angle in 8 different azimuths. Real-time signal processing board is developed to acquire and process the heterodyne mixing signal with 10000 pulses spectra accumulated every second. Wind profiles are obtained every 20 seconds. Several experiments are implemented to evaluate the performance of the lidar. We have carried out airborne wind lidar experiments successfully, and the wind profiles are compared with aerological theodolite and ground based wind lidar. Wind speed standard error of less than 0.4m/s is shown between airborne wind lidar and balloon aerological theodolite.

  18. Using piezoelectric sensors for ultrasonic pulse velocity measurements in concrete

    International Nuclear Information System (INIS)

    Kee, Seong-Hoon; Zhu, Jinying

    2013-01-01

    The ultrasonic pulse velocity (UPV) test has been a widely used non-destructive testing method for concrete structures. However, the conventional UPV test has limitations in consistency of results and applicability in hard-to-access regions of structures. The authors explore the feasibility of embedded piezoelectric (PZT) sensors for ultrasonic measurements in concrete structures. Two PZT sensors were embedded in a reinforced concrete specimen. One sensor worked as an actuator driven by an ultrasonic pulse-receiver, and another sensor worked as a receiver. A series of ultrasonic tests were conducted to investigate the performance of the embedded sensors in crack-free concrete and concrete specimens having a surface-breaking crack under various external loadings. Signals measured by the embedded sensors show a broad bandwidth with a centre frequency around 80 kHz, and very good coherence in the frequency range from 30 to 180 kHz. Furthermore, experimental variability in ultrasonic pulse velocity and attenuation is substantially reduced compared to previously reported values from conventional UPV equipment. Findings from this study demonstrate that the embedded sensors have great potential as a low-cost solution for ultrasonic transducers for health monitoring of concrete in structures. (paper)

  19. Wind stress, curl and vertical velocity in the Bay of Bengal during southwest monsoon, 1984

    Digital Repository Service at National Institute of Oceanography (India)

    Babu, M.T.; Heblekar, A.K.; Murty, C.S.

    Wind distribution observed during southwest monsoon of 1984 has used to derive the mean wind stress for the season at every 1 degree square grid and curl over the Bay of Bengal. Two regions of maximum wind stress are present over the Bay of Bengal...

  1. Remotely measuring the wind using turbine-mounted lidars: Application to power performance testing

    DEFF Research Database (Denmark)

    Borraccino, Antoine

    the so-called whitebox approach. It consists mainly in calibrating the lidar primary measurementsof line-of-sight velocities. The line-of-sight velocity is the projection of the wind vector onto the laser beam propagation path. The calibration is performed in situ, by comparing the lidar velocity...... measurements to a reference quantity itself traceable to the international standards of units. The uncertainty of the line-ofsight velocity measurements was assessed using a normative methodology (GUM) which is based on the law of propagation of uncertainties. The generic calibration procedure was applied...... to two commercially developed nacelle lidars systems, the Avent 5-beam Demonstrator and the ZephIR Dual Mode lidars. Further, the lineof-sight positioning quantities such as inclination angles or beam trajectory werealso calibrated and their uncertainties assessed. Calibration results were of high...

  2. Precise measurement of velocity dependent friction in rotational motion

    Energy Technology Data Exchange (ETDEWEB)

    Alam, Junaid; Hassan, Hafsa; Shamim, Sohaib; Mahmood, Waqas; Anwar, Muhammad Sabieh, E-mail: sabieh@lums.edu.pk [School of Science and Engineering, Lahore University of Management Sciences (LUMS), Opposite Sector U, D.H.A, Lahore 54792 (Pakistan)

    2011-09-15

    Frictional losses are experimentally determined for a uniform circular disc exhibiting rotational motion. The clockwise and anticlockwise rotations of the disc, that result when a hanger tied to a thread is released from a certain height, give rise to vertical oscillations of the hanger as the thread winds and unwinds over a pulley attached to the disc. It is thus observed how the maximum height is achieved by the hanger decrements in every bounce. From the decrements, the rotational frictional losses are measured. The precision is enhanced by correlating vertical motion with the angular motion. This method leads to a substantial improvement in precision. Furthermore, the frictional torque is shown to be proportional to the angular speed. The experiment has been successfully employed in the undergraduate lab setting.

  3. Comparison of wind pressure measurements on Silsoe ...

    African Journals Online (AJOL)

    user

    and the over production of turbulent kinetic energy near the sharp edges. The various RANS ... can predict the general wind conditions around building reasonably well except those in the separation regions .... cable to a remote A/D converter.

  4. Comparison of wind pressure measurements on Silsoe ...

    African Journals Online (AJOL)

    International Journal of Engineering, Science and Technology ... from full-scale observation, wind-tunnel experiments and various CFD techniques ... The paper is the result of extensive research concentrated on analyzing the accuracy and ...

  5. Comparison of wind pressure measurements on Silsoe ...

    African Journals Online (AJOL)

    user

    turbulence models available widely and the state of the art techniques for the ... model, suitable for wind engineering applications, should be able to model the .... the Commonwealth Advisory Aeronautical Council (CAARC) building using vari-.

  6. Proactive monitoring of a wind turbine array with lidar measurements, SCADA data and a data-driven RANS solver

    Science.gov (United States)

    Iungo, G.; Said, E. A.; Santhanagopalan, V.; Zhan, L.

    2016-12-01

    Power production of a wind farm and durability of wind turbines are strongly dependent on non-linear wake interactions occurring within a turbine array. Wake dynamics are highly affected by the specific site conditions, such as topography and local atmospheric conditions. Furthermore, contingencies through the life of a wind farm, such as turbine ageing and off-design operations, make prediction of wake interactions and power performance a great challenge in wind energy. In this work, operations of an onshore wind turbine array were monitored through lidar measurements, SCADA and met-tower data. The atmospheric wind field investing the wind farm was estimated by using synergistically the available data through five different methods, which are characterized by different confidence levels. By combining SCADA data and the lidar measurements, it was possible to estimate power losses connected with wake interactions. For this specific array, power losses were estimated to be 4% and 2% of the total power production for stable and convective atmospheric regimes, respectively. The entire dataset was then leveraged for the calibration of a data-driven RANS (DDRANS) solver for prediction of wind turbine wakes and power production. The DDRANS is based on a parabolic formulation of the Navier-Stokes equations with axisymmetry and boundary layer approximations, which allow achieving very low computational costs. Accuracy in prediction of wind turbine wakes and power production is achieved through an optimal tuning of the turbulence closure model. The latter is based on a mixing length model, which was developed based on previous wind turbine wake studies carried out through large eddy simulations and wind tunnel experiments. Several operative conditions of the wind farm under examination were reproduced through DDRANS for different stability regimes, wind directions and wind velocity. The results show that DDRANS is capable of achieving a good level of accuracy in prediction

  7. Force-velocity measurements of a few growing actin filaments.

    Directory of Open Access Journals (Sweden)

    Coraline Brangbour

    2011-04-01

    Full Text Available The polymerization of actin in filaments generates forces that play a pivotal role in many cellular processes. We introduce a novel technique to determine the force-velocity relation when a few independent anchored filaments grow between magnetic colloidal particles. When a magnetic field is applied, the colloidal particles assemble into chains under controlled loading or spacing. As the filaments elongate, the beads separate, allowing the force-velocity curve to be precisely measured. In the widely accepted Brownian ratchet model, the transduced force is associated with the slowing down of the on-rate polymerization. Unexpectedly, in our experiments, filaments are shown to grow at the same rate as when they are free in solution. However, as they elongate, filaments are more confined in the interspace between beads. Higher repulsive forces result from this higher confinement, which is associated with a lower entropy. In this mechanism, the production of force is not controlled by the polymerization rate, but is a consequence of the restriction of filaments' orientational fluctuations at their attachment point.

  8. Rotor equivalent wind speed for power curve measurement – comparative exercise for IEA Wind Annex 32

    DEFF Research Database (Denmark)

    Wagner, Rozenn; Cañadillas, B.; Clifton, A.

    2014-01-01

    was the definition of the segment area used as weighting for the wind speeds measured at the various heights in the calculation of the REWS. This comparative exercise showed that the REWS method results in a significant difference compared to the standard method using the wind speed at hub height in conditions...

  9. Wind profile modelling using WAsP and "tall" wind measurements

    DEFF Research Database (Denmark)

    Floors, Rogier Ralph; Kelly, Mark C.; Troen, Ib

    2015-01-01

    extrapolations (the wind profile) this is done using the Weibull distribution and the geostrophic drag law. Wind lidar measurements obtained during the ’Tall wind’ campaign at three different sites are used to evaluate the assumptions and equations that are used in the WAsP vertical extrapolation strategy...

  10. Wake Measurements in ECN's Scaled Wind Farm

    Energy Technology Data Exchange (ETDEWEB)

    Wagenaar, J.W.; Schepers, J.G. [ECN Wind Energy, Petten (Netherlands)

    2013-02-15

    In ECN's scaled wind farm the wake evolution is studied in two different situations. A single wake is studied at two different locations downstream of a turbine and a single wake is studied in conjunction with a triple wake. Here, the wake is characterized by the wind speed ratio, the turbulence intensity, the vertical wind speed and the turbulence (an)isotropy. Per situation all wake measurements are taken simultaneously together with the inflow conditions.

  11. Three-dimensional structure of wind turbine wakes as measured by scanning lidar

    Science.gov (United States)

    Bodini, Nicola; Zardi, Dino; Lundquist, Julie K.

    2017-08-01

    The lower wind speeds and increased turbulence that are characteristic of turbine wakes have considerable consequences on large wind farms: turbines located downwind generate less power and experience increased turbulent loads. The structures of wakes and their downwind impacts are sensitive to wind speed and atmospheric variability. Wake characterization can provide important insights for turbine layout optimization in view of decreasing the cost of wind energy. The CWEX-13 field campaign, which took place between June and September 2013 in a wind farm in Iowa, was designed to explore the interaction of multiple wakes in a range of atmospheric stability conditions. Based on lidar wind measurements, we extend, present, and apply a quantitative algorithm to assess wake parameters such as the velocity deficits, the size of the wake boundaries, and the location of the wake centerlines. We focus on wakes from a row of four turbines at the leading edge of the wind farm to explore variations between wakes from the edge of the row (outer wakes) and those from turbines in the center of the row (inner wakes). Using multiple horizontal scans at different elevations, a three-dimensional structure of wakes from the row of turbines can be created. Wakes erode very quickly during unstable conditions and can in fact be detected primarily in stable conditions in the conditions measured here. During stable conditions, important differences emerge between the wakes of inner turbines and the wakes of outer turbines. Further, the strong wind veer associated with stable conditions results in a stretching of the wake structures, and this stretching manifests differently for inner and outer wakes. These insights can be incorporated into low-order wake models for wind farm layout optimization or for wind power forecasting.

  12. Synchronous Surface Pressure and Velocity Measurements of standard model in hypersonic flow

    Directory of Open Access Journals (Sweden)

    Zhijun Sun

    2018-01-01

    Full Text Available Experiments in the Hypersonic Wind tunnel of NUAA(NHW present synchronous measurements of bow shockwave and surface pressure of a standard blunt rotary model (AGARD HB-2, which was carried out in order to measure the Mach-5-flow above a blunt body by PIV (Particle Image Velocimetry as well as unsteady pressure around the rotary body. Titanium dioxide (Al2O3 Nano particles were seeded into the flow by a tailor-made container. With meticulous care designed optical path, the laser was guided into the vacuum experimental section. The transient pressure was obtained around model by using fast-responding pressure-sensitive paint (PSPsprayed on the model. All the experimental facilities were controlled by Series Pulse Generator to ensure that the data was time related. The PIV measurements of velocities in front of the detached bow shock agreed very well with the calculated value, with less than 3% difference compared to Pitot-pressure recordings. The velocity gradient contour described in accord with the detached bow shock that showed on schlieren. The PSP results presented good agreement with the reference data from previous studies. Our work involving studies of synchronous shock-wave and pressure measurements proved to be encouraging.

  13. Wake effects in Alsvik wind park: Comparison between measurements and predictions

    Energy Technology Data Exchange (ETDEWEB)

    Magnusson, Mikael [Uppsala Univ. (Sweden). Dept. of Meteorology; Rados, K.G.; Pothou, K.P. [National Technical Univ., Athen (Greece). Fluid section

    1996-12-01

    In this paper characteristic parameters in a wind turbine wake are studied. The data used are full-scale measurements from a wind farm in Sweden, Alsvik, and results from a numerical model calculated for the same site. The results are valid for neutral stratification. The model employs a particle-vortex approach at the rotor plane, a Navier-Stokes solver in the near wake and applies self preservation in the far wake. The parameters investigated are the relative velocity deficit at centre line and hub height, and the radial distribution of the turbulent kinetic energy. 6 refs, 9 figs

  14. Measuring the Edge Recombination Velocity of Monolayer Semiconductors.

    Science.gov (United States)

    Zhao, Peida; Amani, Matin; Lien, Der-Hsien; Ahn, Geun Ho; Kiriya, Daisuke; Mastandrea, James P; Ager, Joel W; Yablonovitch, Eli; Chrzan, Daryl C; Javey, Ali

    2017-09-13

    Understanding edge effects and quantifying their impact on the carrier properties of two-dimensional (2D) semiconductors is an essential step toward utilizing this material for high performance electronic and optoelectronic devices. WS 2 monolayers patterned into disks of varying diameters are used to experimentally explore the influence of edges on the material's optical properties. Carrier lifetime measurements show a decrease in the effective lifetime, τ effective , as a function of decreasing diameter, suggesting that the edges are active sites for carrier recombination. Accordingly, we introduce a metric called edge recombination velocity (ERV) to characterize the impact of 2D material edges on nonradiative carrier recombination. The unpassivated WS 2 monolayer disks yield an ERV ∼ 4 × 10 4 cm/s. This work quantifies the nonradiative recombination edge effects in monolayer semiconductors, while simultaneously establishing a practical characterization approach that can be used to experimentally explore edge passivation methods for 2D materials.

  15. Determination of groundwater flow velocity by radon measurements

    International Nuclear Information System (INIS)

    Hohn, E.; von Gunten, H.R.

    1990-01-01

    The groundwater resources of glacio-fluvial perialpine valleys are recharged significantly by the infiltration from rivers. The groundwater residence times between rivers and wells should be known in groundwater management problems. Short residence times can be estimated using radon. Radon concentrations in rivers are usually very low. Upon filtration and movement of the water in the ground, radon is picked up and its concentration increases by 2-3 orders of magnitude according to radioactive growth laws. Residence times and flow velocities can be estimated from the increasing radon concentrations measured in groundwater sampling tubes at different distances from the river. Results obtained with this method agree with the results from experiments with artificial tracers

  16. Measurement of pressure distributions and velocity fields of water jet intake flow

    International Nuclear Information System (INIS)

    Jeong, Eun Ho; Yoon, Sang Youl; Kwon, Seong Hoon; Chun, Ho Hwan; Kim, Mun Chan; Kim, Kyung Chun

    2002-01-01

    Waterjet propulsion system can avoid cavitation problem which is being arised conventional propeller propulsion system. The main issue of designing waterjet system is the boundary layer separation at ramp and lib of water inlet. The flow characteristics are highly depended on Jet to Velocity Ratio(JVR) as well as the intake geometry. The present study is conducted in a wind tunnel to provide accurate pressure destribution at the inlet wall and velocity field of the inlet and exit planes. Particle image velocimetry technique is used to obtain detail velocity fields. Pressure distributions and velocity field are discussed with accelerating and deaccelerating flow zones and the effect of JVR

  17. Radio-controlled boat for measuring water velocities and bathymetry

    Science.gov (United States)

    Vidmar, Andrej; Bezak, Nejc; Sečnik, Matej

    2016-04-01

    Radio-controlled boat named "Hi3" was designed and developed in order to facilitate water velocity and bathymetry measurements. The boat is equipped with the SonTek RiverSurveyor M9 instrument that is designed for measuring open channel hydraulics (discharge and bathymetry). Usually channel cross sections measurements are performed either from a bridge or from a vessel. However, these approaches have some limitations such as performing bathymetry measurements close to the hydropower plant turbine or downstream from a hydropower plant gate where bathymetry changes are often the most extreme. Therefore, the radio-controlled boat was designed, built and tested in order overcome these limitations. The boat is made from a surf board and two additional small balance support floats. Additional floats are used to improve stability in fast flowing and turbulent parts of rivers. The boat is powered by two electric motors, steering is achieved with changing the power applied to left and right motor. Furthermore, remotely controlled boat "Hi3" can be powered in two ways, either by a gasoline electric generator or by lithium batteries. Lithium batteries are lighter, quieter, but they operation time is shorter compared to an electrical generator. With the radio-controlled boat "Hi3" we can perform measurements in potentially dangerous areas such as under the lock gates at hydroelectric power plant or near the turbine outflow. Until today, the boat "Hi3" has driven more than 200 km in lakes and rivers, performing various water speed and bathymetry measurements. Moreover, in future development the boat "Hi3" will be upgraded in order to be able to perform measurements automatically. The future plans are to develop and implement the autopilot. With this approach the user will define the route that has to be driven by the boat and the boat will drive the pre-defined route automatically. This will be possible because of the very accurate differential GPS from the Sontek River

  18. Equatorial thermospheric wind changes during the solar cycle: Measurements at Arequipa, Peru, from 1983 to 1990

    International Nuclear Information System (INIS)

    Biondi, M.A.; Meriwether, J.W. Jr.; Fejer, B.G.; Gonzalez, S.A.; Hallenbeck, D.C.

    1991-01-01

    Fabry-Perot interferometer measurements of Doppler shifts in the nightglow 630-nm emission line have been used to determine near-equatorial thermospheric wind velocities at Arequipa, Peru, over ∼ 2/3 of a solar cycle. Monthly-average nocturnal variations in the meridional and zonal wind components were calculated from the nightly data to remove short term (day-to-day) variability, facilitating display of seasonal changes in the wind patterns, as well as any additional changes introduced by the progression of the solar cycle. The measured seasonal variations in the wind patterns are more pronounced than the solar cycle variations and are more readily understandable in terms of the expected, underlying forcing and damping processes. For most of the years, at the winter solstice, there is a weak (≤ 100 m/s) transequatorial flow from the summer to the winter hemisphere in the early and the late night, with essentially zero velocities in between. At the equinoxes, an early-night poleward (southward) flow at solar minimum (1986) is replaced by an equatorward (northward) flow at solar maximum (1989-1990). The zonal flows are predominantly eastward throughout the night, except for the solar minimum equinoxes, where brief westward flows appear in the early and the late night. The peak eastward velocities increase toward solar maximum; at the winter solstice, they are ∼ 100-130 m/s in 1983, 1984 and 1986, reaching ∼ 200 m/s in 1988, 1989 and 1990. The present equatorial thermospheric wind determinations agree in some respects with the satellite-data-based horizontal wind model IIWM-87 and the vector spherical harmonic form of the thermospheric general circulation model

  19. Measurement of acoustic velocity components in a turbulent flow using LDV and high-repetition rate PIV

    Science.gov (United States)

    Léon, Olivier; Piot, Estelle; Sebbane, Delphine; Simon, Frank

    2017-06-01

    The present study provides theoretical details and experimental validation results to the approach proposed by Minotti et al. (Aerosp Sci Technol 12(5):398-407, 2008) for measuring amplitudes and phases of acoustic velocity components (AVC) that are waveform parameters of each component of velocity induced by an acoustic wave, in fully turbulent duct flows carrying multi-tone acoustic waves. Theoretical results support that the turbulence rejection method proposed, based on the estimation of cross power spectra between velocity measurements and a reference signal such as a wall pressure measurement, provides asymptotically efficient estimators with respect to the number of samples. Furthermore, it is shown that the estimator uncertainties can be simply estimated, accounting for the characteristics of the measured flow turbulence spectra. Two laser-based measurement campaigns were conducted in order to validate the acoustic velocity estimation approach and the uncertainty estimates derived. While in previous studies estimates were obtained using laser Doppler velocimetry (LDV), it is demonstrated that high-repetition rate particle image velocimetry (PIV) can also be successfully employed. The two measurement techniques provide very similar acoustic velocity amplitude and phase estimates for the cases investigated, that are of practical interest for acoustic liner studies. In a broader sense, this approach may be beneficial for non-intrusive sound emission studies in wind tunnel testings.

  20. Model Predictive Control of Wind Turbines using Uncertain LIDAR Measurements

    DEFF Research Database (Denmark)

    Mirzaei, Mahmood; Soltani, Mohsen; Poulsen, Niels Kjølstad

    2013-01-01

    , we simplify state prediction for the MPC. Consequently, the control problem of the nonlinear system is simplified into a quadratic programming. We consider uncertainty in the wind propagation time, which is the traveling time of wind from the LIDAR measurement point to the rotor. An algorithm based......The problem of Model predictive control (MPC) of wind turbines using uncertain LIDAR (LIght Detection And Ranging) measurements is considered. A nonlinear dynamical model of the wind turbine is obtained. We linearize the obtained nonlinear model for different operating points, which are determined...... on wind speed estimation and measurements from the LIDAR is devised to find an estimate of the delay and compensate for it before it is used in the controller. Comparisons between the MPC with error compensation, the MPC without error compensation and an MPC with re-linearization at each sample point...

  1. Wind atlas for Egypt: Measurements, micro- and mesoscale modelling

    DEFF Research Database (Denmark)

    Mortensen, N.G.; Hansen, J.C.; Badger, J.

    2006-01-01

    – close to consumers and the electrical grid. The KAMM simulations seem to capture the main features of the wind climate of Egypt, but in regions where the horizontal wind gradients are large, the uncertainties are large as well and additional measurements are required. The results are now published...

  2. Influence of current velocity and wind speed on air-water gas exchange in a mangrove estuary

    Science.gov (United States)

    Ho, David T.; Coffineau, Nathalie; Hickman, Benjamin; Chow, Nicholas; Koffman, Tobias; Schlosser, Peter

    2016-04-01

    Knowledge of air-water gas transfer velocities and water residence times is necessary to study the fate of mangrove derived carbon exported into surrounding estuaries and ultimately to determine carbon balances in mangrove ecosystems. For the first time, the 3He/SF6 dual tracer technique, which has been proven to be a powerful tool to determine gas transfer velocities in the ocean, is applied to Shark River, an estuary situated in the largest contiguous mangrove forest in North America. The mean gas transfer velocity was 3.3 ± 0.2 cm h-1 during the experiment, with a water residence time of 16.5 ± 2.0 days. We propose a gas exchange parameterization that takes into account the major sources of turbulence in the estuary (i.e., bottom generated shear and wind stress).

  3. The role of streamline curvature in sand dune dynamics: evidence from field and wind tunnel measurements

    Science.gov (United States)

    Wiggs, Giles F. S.; Livingstone, Ian; Warren, Andrew

    1996-09-01

    Field measurements on an unvegetated, 10 m high barchan dune in Oman are compared with measurements over a 1:200 scale fixed model in a wind tunnel. Both the field and wind tunnel data demonstrate similar patterns of wind and shear velocity over the dune, confirming significant flow deceleration upwind of and at the toe of the dune, acceleration of flow up the windward slope, and deceleration between the crest and brink. This pattern, including the widely reported upwind reduction in shear velocity, reflects observations of previous studies. Such a reduction in shear velocity upwind of the dune should result in a reduction in sand transport and subsequent sand deposition. This is not observed in the field. Wind tunnel modelling using a near-surface pulse-wire probe suggests that the field method of shear velocity derivation is inadequate. The wind tunnel results exhibit no reduction in shear velocity upwind of or at the toe of the dune. Evidence provided by Reynolds stress profiles and turbulence intensities measured in the wind tunnel suggest that this maintenance of upwind shear stress may be a result of concave (unstable) streamline curvature. These additional surface stresses are not recorded by the techniques used in the field measurements. Using the occurrence of streamline curvature as a starting point, a new 2-D model of dune dynamics is deduced. This model relies on the establishment of an equilibrium between windward slope morphology, surface stresses induced by streamline curvature, and streamwise acceleration. Adopting the criteria that concave streamline curvature and streamwise acceleration both increase surface shear stress, whereas convex streamline curvature and deceleration have the opposite effect, the relationships between form and process are investigated in each of three morphologically distinct zones: the upwind interdune and concave toe region of the dune, the convex portion of the windward slope, and the crest-brink region. The

  4. High spectral resolution lidar based on quad mach zehnder interferometer for aerosols and wind measurements on board space missions

    Science.gov (United States)

    Mariscal, Jean-François; Bruneau, Didier; Pelon, Jacques; Van Haecke, Mathilde; Blouzon, Frédéric; Montmessin, Franck; Chepfer, Hélène

    2018-04-01

    We present the measurement principle and the optical design of a Quad Mach Zehnder (QMZ) interferometer as HSRL technique, allowing simultaneous measurements of particle backscattering and wind velocity. Key features of this concept is to operate with a multimodal laser and do not require any frequency stabilization. These features are relevant especially for space applications for which high technical readiness level is required.

  5. Simulation of the Impact of New Ocean Surface Wind Measurements on H*Wind Analyses

    Science.gov (United States)

    Miller, Timothy; Atlas, Robert; Black, Peter; Chen, Shuyi; Hood, Robbie; Johnson, James; Jones, Linwood; Ruf, Chris; Uhlhorn, Eric

    2008-01-01

    The H*Wind analysis, a product of the Hurricane Research Division of NOAA's Atlantic Oceanographic and Meteorological Laboratory, brings together wind measurements from a variety of observation platforms into an objective analysis of the distribution of surface wind speeds in a tropical cyclone. This product is designed to improve understanding of the extent and strength of the wind field, and to improve the assessment of hurricane intensity. See http://www.aoml.noaa.gov/hrd/data sub/wind.html. The Hurricane Imaging Radiometer (HIRAD) is a new passive microwave remote sensor for hurricane observations that is currently under development by NASA Marshall Space Flight Center, NOAA Hurricane Research Division, the University of Central Florida and the University of Michigan. HIRAD is being designed to enhance the current real-time airborne ocean surface winds observation capabilities of NOAA and USAF Weather Squadron hurricane hunter aircraft using the operational airbome Stepped Frequency Microwave Radiometer (SFMR). Unlike SFMR, which measures wind speed and rain rate along the ground track directly beneath the aircraft, HIRAD will provide images of the surface wind and rain field over a wide swath (approximately 3 x the aircraft altitude, or approximately 2 km from space). The instrument is described in a separate paper presented at this conference. The present paper describes a set of Observing System Simulation Experiments (OSSEs) in which measurements from the new instrument as well as those from existing instruments (air, surface, and space-based) are simulated from the output of a numerical model from the University of Miami, and those results are used to construct H*Wind analyses. Evaluations will be presented on the relative impact of HIRAD and other instruments on H*Wind analyses, including the use of HIRAD from 2 aircraft altitudes and from a space-based platform.

  6. Pressure field in measurement section of wind tunnel

    Directory of Open Access Journals (Sweden)

    Hnidka Jakub

    2017-01-01

    Full Text Available The University of Defence in Brno has a new low-speed wind tunnel. In order to confirm the quality of the wind inside of the measurement section, several measurements of the dynamic pressure have been performed with the Pitot-static tube. The pressure fields are then analysed and quality of the field is evaluated. Measurement of a pressure drop on the body of a standing helicopter was conducted.

  7. Comparison of 3D turbulence measurements using three staring wind lidars and a sonic anemometer

    DEFF Research Database (Denmark)

    Mann, Jakob; Cariou, J.-P.; Courtney, Michael

    2008-01-01

    Three pulsed lidars were used in staring, non-scanning mode, placed so that their beams crossed close to a 3D sonic anemometer. The goal is to compare lidar volume averaged wind measurement with point measurement reference sensors and to demonstrate the feasibility of performing 3D turbulence mea...... measurements with lidars. The results show a very good correlation between the lidar and the sonic times series. The variance of the velocity measured by the Mar is attenuated due to spatial filtering, and the amount of attenuation can be predicted theoretically.......Three pulsed lidars were used in staring, non-scanning mode, placed so that their beams crossed close to a 3D sonic anemometer. The goal is to compare lidar volume averaged wind measurement with point measurement reference sensors and to demonstrate the feasibility of performing 3D turbulence...

  8. Video Measurement of the Muzzle Velocity of a Potato Gun

    Science.gov (United States)

    Jasperson, Christopher; Pollman, Anthony

    2011-01-01

    Using first principles, a theoretical equation for the maximum and actual muzzle velocities for a pneumatic cannon was recently derived. For a fixed barrel length, this equation suggests that the muzzle velocity can be enhanced by maximizing the product of the initial pressure and the volume of the propellant gas and decreasing the projectile…

  9. Particle velocity measurements in laser irradiated foils using ORVIS

    International Nuclear Information System (INIS)

    Sheffield, S.A.; Fisk, G.A.

    1983-01-01

    Aluminum foils from 2- to 200-μm thick have been subjected to a Nd:YAG laser pulse of low irradiance (10 9 W/cm 2 , approx. 10 ns pulse) to produce laser-driven shocks in the foils. The particle velocity history of the foil side opposite the laser deposition was monitored with nanosecond resolution by a velocity interferometer system called ORVIS. These histories indicate a shock reverberation process accelerates the foil. Peak foil velocities can be adequately calculated using a ricket propulsion model developed from experiments at much higher irradiances. A velocity of 1 km/s was developed in a 2-μm-thick free foil in a time of 50 ns. Water-confined foils attained peak particle velocities about three times higher than those of free foils

  10. On the prediction of threshold friction velocity of wind erosion using soil reflectance spectroscopy

    Science.gov (United States)

    Li, Junran; Flagg, Cody B.; Okin, Gregory S.; Painter, Thomas H.; Dintwe, Kebonye; Belnap, Jayne

    2015-01-01

    Current approaches to estimate threshold friction velocity (TFV) of soil particle movement, including both experimental and empirical methods, suffer from various disadvantages, and they are particularly not effective to estimate TFVs at regional to global scales. Reflectance spectroscopy has been widely used to obtain TFV-related soil properties (e.g., moisture, texture, crust, etc.), however, no studies have attempted to directly relate soil TFV to their spectral reflectance. The objective of this study was to investigate the relationship between soil TFV and soil reflectance in the visible and near infrared (VIS–NIR, 350–2500 nm) spectral region, and to identify the best range of wavelengths or combinations of wavelengths to predict TFV. Threshold friction velocity of 31 soils, along with their reflectance spectra and texture were measured in the Mojave Desert, California and Moab, Utah. A correlation analysis between TFV and soil reflectance identified a number of isolated, narrow spectral domains that largely fell into two spectral regions, the VIS area (400–700 nm) and the short-wavelength infrared (SWIR) area (1100–2500 nm). A partial least squares regression analysis (PLSR) confirmed the significant bands that were identified by correlation analysis. The PLSR further identified the strong relationship between the first-difference transformation and TFV at several narrow regions around 1400, 1900, and 2200 nm. The use of PLSR allowed us to identify a total of 17 key wavelengths in the investigated spectrum range, which may be used as the optimal spectral settings for estimating TFV in the laboratory and field, or mapping of TFV using airborne/satellite sensors.

  11. Representativeness of wind measurements in moderately complex terrain

    Science.gov (United States)

    van den Bossche, Michael; De Wekker, Stephan F. J.

    2018-02-01

    We investigated the representativeness of 10-m wind measurements in a 4 km × 2 km area of modest relief by comparing observations at a central site with those at four satellite sites located in the same area. Using a combination of established and new methods to quantify and visualize representativeness, we found significant differences in wind speed and direction between the four satellite sites and the central site. The representativeness of the central site wind measurements depended strongly on surface wind speed and direction, and atmospheric stability. Through closer inspection of the observations at one of the satellite sites, we concluded that terrain-forced flows combined with thermally driven downslope winds caused large biases in wind direction and speed. We used these biases to generate a basic model, showing that terrain-related differences in wind observations can to a large extent be predicted. Such a model is a cost-effective way to enhance an area's wind field determination and to improve the outcome of pollutant dispersion and weather forecasting models.

  12. 3D turbulence measurements in inhomogeneous boundary layers with three wind LiDARs

    Science.gov (United States)

    Carbajo Fuertes, Fernando; Valerio Iungo, Giacomo; Porté-Agel, Fernando

    2014-05-01

    One of the most challenging tasks in atmospheric anemometry is obtaining reliable turbulence measurements of inhomogeneous boundary layers at heights or in locations where is not possible or convenient to install tower-based measurement systems, e.g. mountainous terrain, cities, wind farms, etc. Wind LiDARs are being extensively used for the measurement of averaged vertical wind profiles, but they can only successfully accomplish this task under the limiting conditions of flat terrain and horizontally homogeneous flow. Moreover, it has been shown that common scanning strategies introduce large systematic errors in turbulence measurements, regardless of the characteristics of the flow addressed. From the point of view of research, there exist a variety of techniques and scanning strategies to estimate different turbulence quantities but most of them rely in the combination of raw measurements with atmospheric models. Most of those models are only valid under the assumption of horizontal homogeneity. The limitations stated above can be overcome by a new triple LiDAR technique which uses simultaneous measurements from three intersecting Doppler wind LiDARs. It allows for the reconstruction of the three-dimensional velocity vector in time as well as local velocity gradients without the need of any turbulence model and with minimal assumptions [EGU2013-9670]. The triple LiDAR technique has been applied to the study of the flow over the campus of EPFL in Lausanne (Switzerland). The results show the potential of the technique for the measurement of turbulence in highly complex boundary layer flows. The technique is particularly useful for micrometeorology and wind engineering studies.

  13. Magnetic Geared Radial Axis Vertical Wind Turbine for Low Velocity Regimes

    Directory of Open Access Journals (Sweden)

    Wei Wei Teow

    2018-01-01

    Full Text Available In the 21st century, every country is seeking an alternative source of energy especially the renewable sources. There are considerable developments in the wind energy technology in recent years and in more particular on the vertical axis wind turbine (VAWT as they are modular, less installation cost and portable in comparison with that of the horizontal axis wind turbine (HAWT systems. The cut-in speed of a conventional wind turbine is 3.5 m/s to 5 m/s. Mechanical geared generators are commonly found in wind technology to step up power conversion to accommodate the needs of the generator. Wind turbine gearboxes suffer from overload problem and frequent maintenance in spite of the high torque density produced. However, an emerging alternative to gearing system is Magnetic Gear (MG as it offers significant advantages such as free from maintenance and inherent overload protection. In this project, numerical analysis is done on designed magnetic gear greatly affects the performance of the generator in terms of voltage generation. Magnetic flux density is distributed evenly across the generator as seen from the uniform sinusoidal output waveform. Consequently, the interaction of the magnetic flux of the permanent magnets has shown no disturbance to the output of the generator as the voltage generated shows uniform waveform despite the rotational speed of the gears. The simulation is run at low wind speed and the results show that the generator starts generating a voltage of 240 V at a wind speed of 1.04 m/s. This shows great improvement in the operating capability of the wind turbine.

  14. Wind measurement on the Linth plain; Windmessung in der Linthebene

    Energy Technology Data Exchange (ETDEWEB)

    Langraf, B.

    2003-07-01

    This comprehensive final report for the Swiss Federal Office of Energy (SFOE) presents the results of wind measurements made on the Linth plain, a flat alluvial plain in eastern Switzerland located between mountain ranges. The data, which were collected using temporary measurement masts at two locations are presented in the form of tables, diagrams and maps showing the wind-energy potential of various areas of the plain. The actual measurements are compared with prognoses from a geo-information system. The wind measurement equipment and installations are described, as are the software models for the calculation of wind direction, wind intensity and of a prognosis for energy production. Particular attention was also paid to the question of wind turbulence. Further factors investigated included the possibility of icing-up in winter and the choice of a meteorological station in the neighbourhood with similar characteristics that could be used as a reference station. The report also presents the results of the evaluation of various possible locations for wind turbines on the Linth plain. Visual, noise and shadow-casing factors are considered.

  15. High-altitude wind prediction and measurement technology assessment

    Science.gov (United States)

    2009-06-30

    The principles and operational characteristics of balloon and radar-based techniques for measuring upper air winds in support of launches and recoveries are presented. Though either a balloon or radar system could serve as a standalone system, the sa...

  16. Wind Ressources in Complex Terrain investigated with Synchronized Lidar Measurements

    Science.gov (United States)

    Mann, J.; Menke, R.; Vasiljevic, N.

    2017-12-01

    The Perdigao experiment was performed by a number of European and American universities in Portugal 2017, and it is probably the largest field campaign focussing on wind energy ressources in complex terrain ever conducted. 186 sonic anemometers on 50 masts, 20 scanning wind lidars and a host of other instruments were deployed. The experiment is a part of an effort to make a new European wind atlas. In this presentation we investigate whether scanning the wind speed over ridges in this complex terrain with multiple Doppler lidars can lead to an efficient mapping of the wind resources at relevant positions. We do that by having pairs of Doppler lidars scanning 80 m above the ridges in Perdigao. We compare wind resources obtained from the lidars and from the mast-mounted sonic anemometers at 80 m on two 100 m masts, one on each of the two ridges. In addition, the scanning lidar measurements are also compared to profiling lidars on the ridges. We take into account the fact that the profiling lidars may be biased due to the curvature of the streamlines over the instrument, see Bingol et al, Meteorolog. Z. vol. 18, pp. 189-195 (2009). We also investigate the impact of interruptions of the lidar measurements on the estimated wind resource. We calculate the relative differences of wind along the ridge from the lidar measurements and compare those to the same obtained from various micro-scale models. A particular subject investigated is how stability affects the wind resources. We often observe internal gravity waves with the scanning lidars during the night and we quantify how these affect the relative wind speed on the ridges.

  17. Comparison of 3D turbulence measurements using three staring wind lidars and a sonic anemometer

    International Nuclear Information System (INIS)

    Mann, J; Courtney, M S; Mikkelsen, T; Wagner, R; Lindeloew, P; Sjoeholm, M; Enevoldsen, K; Cariou, J-P; Parmentier, R

    2008-01-01

    Three pulsed lidars were used in staring, non-scanning mode, placed so that their beams crossed close to a 3D sonic anemometer. The goal is to compare lidar volume averaged wind measurement with point measurement reference sensors and to demonstrate the feasibility of performing 3D turbulence measurements with lidars. The results show a very good correlation between the lidar and the sonic times series. The variance of the velocity measured by the lidar is attenuated due to spatial filtering, and the amount of attenuation can be predicted theoretically

  18. Measurement of surface recombination velocity on heavily doped indium phosphide

    International Nuclear Information System (INIS)

    Jenkins, P.; Ghalla-Goradia, M.; Faur, M.; Bailey, S.

    1990-01-01

    The controversy surrounding the published low values of surface recombination velocity (SRV) in n-InP, solidified in recent years when modeling of existing n/p InP solar cells revealed that the front surface SRV had to be higher than 1 x 10 6 cm/sec in order to justify the poor blue response that is characteristic of all n/p InP solar cells. In this paper, SRV on heavily doped (>10 18 cm -3 )n-type and p-type InP is measured as a function of surface treatment. For the limited range of substrates and surface treatments studied, SRV and surface stability depend strongly on the surface treatment. SRVs of ∼10 5 cm/sec in both p-type and n-type InP are obtainable, but in n-type the low SRV surfaces were unstable, and the only stable surfaces on n-type had SRVs of >10 6 cm/sec

  19. Empirical wind retrieval model based on SAR spectrum measurements

    Science.gov (United States)

    Panfilova, Maria; Karaev, Vladimir; Balandina, Galina; Kanevsky, Mikhail; Portabella, Marcos; Stoffelen, Ad

    The present paper considers polarimetric SAR wind vector applications. Remote-sensing measurements of the near-surface wind over the ocean are of great importance for the understanding of atmosphere-ocean interaction. In recent years investigations for wind vector retrieval using Synthetic Aperture Radar (SAR) data have been performed. In contrast with scatterometers, a SAR has a finer spatial resolution that makes it a more suitable microwave instrument to explore wind conditions in the marginal ice zones, coastal regions and lakes. The wind speed retrieval procedure from scatterometer data matches the measured radar backscattering signal with the geophysical model function (GMF). The GMF determines the radar cross section dependence on the wind speed and direction with respect to the azimuthal angle of the radar beam. Scatterometers provide information on wind speed and direction simultaneously due to the fact that each wind vector cell (WVC) is observed at several azimuth angles. However, SAR is not designed to be used as a high resolution scatterometer. In this case, each WVC is observed at only one single azimuth angle. That is why for wind vector determination additional information such as wind streak orientation over the sea surface is required. It is shown that the wind vector can be obtained using polarimetric SAR without additional information. The main idea is to analyze the spectrum of a homogeneous SAR image area instead of the backscattering normalized radar cross section. Preliminary numerical simulations revealed that SAR image spectral maxima positions depend on the wind vector. Thus the following method for wind speed retrieval is proposed. In the first stage of the algorithm, the SAR spectrum maxima are determined. This procedure is carried out to estimate the wind speed and direction with ambiguities separated by 180 degrees due to the SAR spectrum symmetry. The second stage of the algorithm allows us to select the correct wind direction

  20. Simplified equations for the rotational speed response to inflow velocity variation in fixed-pitch small wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, H; Hasegawa, Y, E-mail: hsuzuki@nitech.ac.jp [Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan)

    2015-02-01

    We propose simplified equations for the rotational speed response to inflow velocity variation in fixed-pitch small wind turbines. The present formulation is derived by introducing a series expansion for the torque coefficient at the constant tip-speed ratio. By focusing on the first- and second-order differential coefficients of the torque coefficient, we simplify the original differential equation. The governing equation based only on the first-order differential coefficient is found to be linear, whereas the second-order differential coefficient introduces nonlinearity. We compare the numerical solutions of the three governing equations for rotational speed in response to sinusoidal and normal-random variations of inflow velocity. The linear equation gives accurate solutions of amplitude and phase lag. Nonlinearity occurs in the mean value of rotational speed variation. We also simulate the rotational speed in response to a step input of inflow velocity using the conditions of two previous studies, and note that the form of this rotational speed response is a system of first-order time lag. We formulate the gain and time constant for this rotational speed response. The magnitude of the gain is approximately three when the wind turbine is operated at optimal tip-speed ratio. We discuss the physical meaning of the derived time constant. (paper)

  1. Measuring Gas Concentration and Wind Intensity in a Turbulent Wind Tunnel with a Mobile Robot

    Directory of Open Access Journals (Sweden)

    Dani Martínez

    2016-01-01

    Full Text Available This paper presents the measurement of gas concentration and wind intensity performed with a mobile robot in a custom turbulent wind tunnel designed for experimentation with customizable wind and gas leak sources. This paper presents the representation in different information layers of the measurements obtained in the turbulent wind tunnel under different controlled environmental conditions in order to describe the plume of the gas and wind intensities inside the experimentation chamber. The information layers have been generated from the measurements gathered by individual onboard gas and wind sensors carried out by an autonomous mobile robot. On the one hand, the assumption was that the size and cost of these specialized sensors do not allow the creation of a net of sensors or other measurement alternatives based on the simultaneous use of several sensors, and on the other hand, the assumption is that the information layers created will have application on the development and test of automatic gas source location procedures based on reactive or nonreactive algorithms.

  2. Optical measurements of winds in the lower thermosphere

    International Nuclear Information System (INIS)

    Wiens, R.H.; Shepherd, G.G.; Gault, W.A.; Kosteniuk, P.R.

    1988-01-01

    WAMDII, the wide-angle Michelson Doppler imaging interferometer, was used to measure the neutral wind in the lower thermosphere by the Doppler shift of the O I 557-nm line. Observations were made at Saskatoon (60.5 degree N invariant) around the spring equinox of 1985 with WAMDII coupled to an all-sky lens. With dopplergrams averaged over 3 to 30 min, no evidence was found for persistent highly localized winds on either of the two nights studied, one viewing only aurora and one viewing only airglow. The nocturnal variation was determined for both nights using average horizontal wind for the whole all-sky image. The pattern for the auroral case shows winds parallel to the aurora orientation in the evening but substantial crosswinds near midnight. High latitude general circulation models seem to represent this case better than local auroral generation models. The airglow case showed eastward winds in the morning sector

  3. Simultaneous measurements with 3D PIV and Acoustic Doppler Velocity Profiler

    NARCIS (Netherlands)

    Blanckaert, K.J.F.; McLelland, S.J.

    2009-01-01

    Simultaneous velocity measurements were taken using Particle Image Velocimetry (PIV) and an Acoustic Doppler Velocity Profiler (ADVP) in a sharp open-channel bend with an immobile gravel bed. The PIV measures 3D velocity vectors in a vertical plane (~40cm x 20cm) at a frequency of 7.5 Hz, whereas

  4. 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

  5. The Velocity Distribution Of Pickup He+ Measured at 0.3 AU by MESSENGER

    Science.gov (United States)

    Gershman, Daniel J.; Fisk, Lennard A.; Gloeckler, George; Raines, Jim M.; Slavin, James A.; Zurbuchen, Thomas H.; Solomon, Sean C.

    2014-06-01

    During its interplanetary trajectory in 2007-2009, the MErcury Surface, Space ENvrionment, GEochemistry, and Ranging (MESSENGER) spacecraft passed through the gravitational focusing cone for interstellar helium multiple times at a heliocentric distance R ≈ 0.3 AU. Observations of He+ interstellar pickup ions made by the Fast Imaging Plasma Spectrometer sensor on MESSENGER during these transits provide a glimpse into the structure of newly formed inner heliospheric pickup-ion distributions. This close to the Sun, these ions are picked up in a nearly radial interplanetary magnetic field. Compared with the near-Earth environment, pickup ions observed near 0.3 AU will not have had sufficient time to be energized substantially. Such an environment results in a nearly pristine velocity distribution function that should depend only on pickup-ion injection velocities (related to the interstellar gas), pitch-angle scattering, and cooling processes. From measured energy-per-charge spectra obtained during multiple spacecraft observational geometries, we have deduced the phase-space density of He+ as a function of magnetic pitch angle. Our measurements are most consistent with a distribution that decreases nearly monotonically with increasing pitch angle, rather than the more commonly modeled isotropic or hemispherically symmetric forms. These results imply that pitch-angle scattering of He+ may not be instantaneous, as is often assumed, and instead may reflect the velocity distribution of initially injected particles. In a slow solar wind stream, we find a parallel-scattering mean free path of λ || ~ 0.1 AU and a He+ production rate of ~0.05 m-3 s-1 within 0.3 AU.

  6. Video measurements of fluid velocities and water levels in breaking waves

    CSIR Research Space (South Africa)

    Govender, K

    2002-01-01

    Full Text Available The cost-effective measurement of the velocity flow fields in breaking water waves, using particle and correlation image velocimetry, is described. The fluid velocities are estimated by tracking the motion of neutrally buoyant particles and aeration...

  7. Phasor measurement of wind power plant operation in Eastern Denmark

    DEFF Research Database (Denmark)

    Rasmussen, Joana; Nielsen, Arne Hejde

    2007-01-01

    Four Phasor Measurement Units (PMUs) record continuously voltage and current phasors in the 400 kV and 132 kV transmission system of Eastern Denmark. The abstract evaluates the unique concept for power system monitoring using PMUs. It focuses on utilization of synchronized phasor measurements from...... Nysted off-shore wind farm during a severe storm in 2005. The wind speeds during the event were so high, that Nysted offshore wind farm as well as a significant amount of on-land wind production in Denmark was disconnected from the grid. The PMU analysis illustrates that PMUs complement the traditional...... measurements from a traditional SCADA system. The case reveals the close relation between voltages, power flows and voltage phase angles over a wide area....

  8. Intensity of the Fe XV emission line corona, the level of geomagnetic activity and the velocity of the solar wind

    International Nuclear Information System (INIS)

    Bell, B.; Noci, G.

    1976-01-01

    The average solar wind velocity and the level of geomagnetic activity (Kp) following central meridian passage of coronal weak and bright features identified from Oso 7 isophotograms of Fe XV (284 A) are determined by the method of superposed epochs. Results are consistent with the concept that bright regions possess magnetic field of closed configurations, thereby reducing particle escape, while coronal holes possess open magnetic field lines favorable to particle escape or enhanced outflow of the solar wind. Coronal holes are identified with Bartels' M regions not only statistically but by linking specific long-lived holes with individual sequences of geomagnetic storms. In the study of bright region a subdivision by brightness temperature (T/sub b/) of associated 9.1-cm radiation was found to be significant, with the region s of higher T/sub b/ having a stronger inhibiting power on the outflow of the solar wind when they were located in the solar hemisphere on the same side of the solar equator as the earth. Regions of highest T/sub b/ most strongly depress the outflow of solar wind but are also the most likely to produce flare-associated great storms

  9. "Rapid Revisit" Measurements of Sea Surface Winds Using CYGNSS

    Science.gov (United States)

    Park, J.; Johnson, J. T.

    2017-12-01

    The Cyclone Global Navigation Satellite System (CYGNSS) is a space-borne GNSS-R (GNSS-Reflectometry) mission that launched December 15, 2016 for ocean surface wind speed measurements. CYGNSS includes 8 small satellites in the same LEO orbit, so that the mission provides wind speed products having unprecedented coverage both in time and space to study multi-temporal behaviors of oceanic winds. The nature of CYGNSS coverage results in some locations on Earth experiencing multiple wind speed measurements within a short period of time (a "clump" of observations in time resulting in a "rapid revisit" series of measurements). Such observations could seemingly provide indications of regions experiencing rapid changes in wind speeds, and therefore be of scientific utility. Temporally "clumped" properties of CYGNSS measurements are investigated using early CYGNSS L1/L2 measurements, and the results show that clump durations and spacing vary with latitude. For example, the duration of a clump can extend as long as a few hours at higher latitudes, with gaps between clumps ranging from 6 to as high as 12 hours depending on latitude. Examples are provided to indicate the potential of changes within a clump to produce a "rapid revisit" product for detecting convective activity. Also, we investigate detector design for identifying convective activities. Results from analyses using recent CYGNSS L2 winds will be provided in the presentation.

  10. ACCUWIND - Accurate wind speed measurements in wind energy - Summary report[Cup and sonic anemometers

    Energy Technology Data Exchange (ETDEWEB)

    Friis Pedersen, T.; Dahlberg, J.Aa.; Cuerva, A.; Mouzakis, F.; Busche, P.; Eecen, P.; Sanz-Andres, A.; Franchini, S.; Markkilde Petersen, S.

    2006-07-15

    The cup anemometer is at present the standard instrument used for mean wind speed measurement in wind energy. It is being applied in high numbers around the world for wind energy assessments. It is also applied exclusively for accredited power performance measurements for certification and verification purposes, and for purposes of optimisation in research and development. The revised IEC standard on power performance measurements has now included requirements for classification of cup anemometers. The basis for setting up such requirements of cup anemometers is two EU projects SITEPARIDEN and CLASSCUP from which the proposed classification method for cup anemometers was developed for the IEC standard. While cup anemometers at present are the standard anemometer being used for average wind speed measurements, sonic anemometers have been developed significantly over the last years, and prices have come down. The application of sonic anemometers may increase in wind energy if they prove to have comparable or better operational characteristics compared to cup anemometers, and if similar requirements to sonic anemometers are established as for cup anemometers. Sonic anemometers have historically been used by meteorologists for turbulence measurements, but have also found a role on wind turbine nacelles for wind speed and yaw control purposes. The report on cup and sonic anemometry deals with establishment of robustness in assessment and classification by focus on methods and procedures for analysis of characteristics of cup and sonic anemometers. The methods and procedures provide a platform, hopefully for use in meeting the requirements of the IEC standard on power performance measurements, as well as for development of improved instruments. (au)

  11. Physics-based Tests to Identify the Accuracy of Solar Wind Ion Measurements: A Case Study with the Wind Faraday Cups

    Science.gov (United States)

    Kasper, J. C.; Lazarus, A. J.; Steinberg, J. T.; Ogilvie, K. W.; Szabo, A.

    2006-01-01

    We present techniques for comparing measurements of velocity, temperature, and density with constraints imposed by the plasma physics of magnetized bi-Maxwellian ions. Deviations from these physics-based constraints are interpreted as arising from measurement errors. Two million ion spectra from the Solar Wind Experiment Faraday Cup instruments on the Wind spacecraft are used as a case study. The accuracy of velocity measurements is determined by the fact that differential flow between hydrogen and helium should be aligned with the ambient magnetic field. Modeling the breakdown of field alignment suggests velocity uncertainties are less than 0.16% in magnitude and 3deg in direction. Temperature uncertainty is found by examining the distribution of observed temperature anisotropies in high-beta solar wind intervals where the firehose, mirror, and cyclotron microinstabilities should drive the distribution to isotropy. The presence of a finite anisotropy at high beta suggests overall temperature uncertainties of 8%. Hydrogen and helium number densities are compared with the electron density inferred from observations of the local electron plasma frequency as a function of solar wind speed and year. We find that after accounting for the contribution of minor ions, the results are consistent with a systematic offset between the two instruments of 34%. The temperature and density methods are sensitive to non-Maxwellian features such as heat flux and proton beams and as a result are more suited to slow solar wind where these features are rare. These procedures are of general use in identifying the accuracy of observations from any solar wind ion instrument.

  12. A study of the river velocity measurement techniques and analysis methods

    Science.gov (United States)

    Chung Yang, Han; Lun Chiang, Jie

    2013-04-01

    Velocity measurement technology can be traced back to the pitot tube velocity measurement method in the 18th century and today's velocity measurement technology use the acoustic and radar technology, with the Doppler principle developed technology advances, in order to develop the measurement method is more suitable for the measurement of velocity, the purpose is to get a more accurate measurement data and with the surface velocity theory, the maximum velocity theory and the indicator theory to obtain the mean velocity. As the main research direction of this article is to review the literature of the velocity measurement techniques and analysis methods, and to explore the applicability of the measurement method of the velocity measurement instruments, and then to describe the advantages and disadvantages of the different mean velocity profiles analysis method. Adequate review of the references of this study will be able to provide a reference for follow-up study of the velocity measurement. Review velocity measurement literature that different velocity measurement is required to follow the different flow conditions measured be upgraded its accuracy, because each flow rate measurement method has its advantages and disadvantages. Traditional velocity instrument can be used at low flow and RiverRAD microwave radar or imaging technology measurement method may be applied in high flow. In the tidal river can use the ADCP to quickly measure river vertical velocity distribution. In addition, urban rivers may be used the CW radar to set up on the bridge, and wide rivers can be used RiverRAD microwave radar to measure the velocities. Review the relevant literature also found that using Ultrasonic Doppler Current Profiler with the Chiu's theory to the velocity of observing automation work can save manpower and resources to improve measurement accuracy, reduce the risk of measurement, but the great variability of river characteristics in Taiwan and a lot of drifting floating

  13. Research on Water Velocity Measurement of Reservoir Based on Pressure Sensor

    Directory of Open Access Journals (Sweden)

    Xiaoqiang Zhao

    2014-11-01

    Full Text Available To address the problem that pressure sensor can only measure the liquid level in reservoir, we designed a current velocity measurement system of reservoir based on pressure sensor, analyzed the error of current velocity measurement system, and proposed the error processing method and corresponding program. Several tests and experimental results show that in this measurement system, the liquid level measurement standard deviation is no more than 0.01 cm, and the current velocity measurement standard deviation is no more than 0.35 mL/s, which proves that the pressure sensor can measure both liquid level and current velocity synchronously.

  14. The sound power measurement and certification of wind turbines

    International Nuclear Information System (INIS)

    MacKinnon, A.; Henderson, R.

    1992-01-01

    It is anticipated that there will be a substantial growth in the exploitation of renewable energy from the wind over the next few years. A major factor in this expected growth is the environmental acceptance or otherwise of wind turbines and in particular their acoustic characteristics. It is generally accepted within the turbine community that reliable methods of measuring and quantifying a turbine's acoustic signature are essential if this exploitation is to be realised. This paper will seek to review current practice both in the UK and further afield and will describe the development of a practical and reliable test method, which will aid the wind turbine Manufacturer, Developer and Planner. (author)

  15. Cup anemometer response to the wind turbulence-measurement of the horizontal wind variance

    Directory of Open Access Journals (Sweden)

    S. Yahaya

    2004-11-01

    Full Text Available This paper presents some dynamic characteristics of an opto-electronic cup anemometer model in relation to its response to the wind turbulence. It is based on experimental data of the natural wind turbulence measured both by an ultrasonic anemometer and two samples of the mentioned cup anemometer. The distance constants of the latter devices measured in a wind tunnel are in good agreement with those determined by the spectral analysis method proposed in this study. In addition, the study shows that the linear compensation of the cup anemometer response, beyond the cutoff frequency, is limited to a given frequency, characteristic of the device. Beyond this frequency, the compensation effectiveness relies mainly on the wind characteristics, particularly the direction variability and the horizontal turbulence intensity. Finally, this study demonstrates the potential of fast cup anemometers to measure some turbulence parameters (like wind variance with errors of the magnitude as those deriving from the mean speed measurements. This result proves that fast cup anemometers can be used to assess some turbulence parameters, especially for long-term measurements in severe climate conditions (icing, snowing or sandy storm weathers.

  16. Precise Measurement of Velocity Dependent Friction in Rotational Motion

    Science.gov (United States)

    Alam, Junaid; Hassan, Hafsa; Shamim, Sohaib; Mahmood, Waqas; Anwar, Muhammad Sabieh

    2011-01-01

    Frictional losses are experimentally determined for a uniform circular disc exhibiting rotational motion. The clockwise and anticlockwise rotations of the disc, that result when a hanger tied to a thread is released from a certain height, give rise to vertical oscillations of the hanger as the thread winds and unwinds over a pulley attached to the…

  17. Noise measurement at wind power plants; Geraeuschmessung an Windenergieanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Schoene, Ralph [Cirrus Research plc, Frankfurt am Main (Germany)

    2012-09-15

    Wind energy is a supporting pillar of the energy transition. For further expansion, it is important to reduce prejudices, for example by measurements as precise as possible and assessments of the often unobjectively discussed noise emissions. These measurements are based on instruments which can analyze and measure low-frequency sound.

  18. Estimated carotid-femoral pulse wave velocity has similar predictive value as measured carotid-femoral pulse wave velocity

    DEFF Research Database (Denmark)

    Olsen, Michael; Greve, Sara; Blicher, Marie

    2016-01-01

    OBJECTIVE: Carotid-femoral pulse wave velocity (cfPWV) adds significantly to traditional cardiovascular (CV) risk prediction, but is not widely available. Therefore, it would be helpful if cfPWV could be replaced by an estimated carotid-femoral pulse wave velocity (ePWV) using age and mean blood...... pressure and previously published equations. The aim of this study was to investigate whether ePWV could predict CV events independently of traditional cardiovascular risk factors and/or cfPWV. DESIGN AND METHOD: cfPWV was measured and ePWV calculated in 2366 apparently healthy subjects from four age...

  19. Improvement of vertical velocity statistics measured by a Doppler lidar through comparison with sonic anemometer observations

    Science.gov (United States)

    Bonin, Timothy A.; Newman, Jennifer F.; Klein, Petra M.; Chilson, Phillip B.; Wharton, Sonia

    2016-12-01

    Since turbulence measurements from Doppler lidars are being increasingly used within wind energy and boundary-layer meteorology, it is important to assess and improve the accuracy of these observations. While turbulent quantities are measured by Doppler lidars in several different ways, the simplest and most frequently used statistic is vertical velocity variance (w'2) from zenith stares. However, the competing effects of signal noise and resolution volume limitations, which respectively increase and decrease w'2, reduce the accuracy of these measurements. Herein, an established method that utilises the autocovariance of the signal to remove noise is evaluated and its skill in correcting for volume-averaging effects in the calculation of w'2 is also assessed. Additionally, this autocovariance technique is further refined by defining the amount of lag time to use for the most accurate estimates of w'2. Through comparison of observations from two Doppler lidars and sonic anemometers on a 300 m tower, the autocovariance technique is shown to generally improve estimates of w'2. After the autocovariance technique is applied, values of w'2 from the Doppler lidars are generally in close agreement (R2 ≈ 0.95 - 0.98) with those calculated from sonic anemometer measurements.

  20. Development of Rayleigh Doppler lidar for measuring middle atmosphere winds

    Science.gov (United States)

    Raghunath, K.; Patra, A. K.; Narayana Rao, D.

    Interpretation of most of the middle and upper atmospheric dynamical and chemical data relies on the climatological description of the wind field Rayleigh Doppler lidar is one instrument which monitors wind profiles continuously though continuity is limited to clear meteorological conditions in the middle atmosphere A Doppler wind lidar operating in incoherent mode gives excellent wind and temperature information at these altitudes with necessary spectral sensitivity It observes atmospheric winds by measuring the spectral shift of the scattered light due to the motions of atmospheric molecules with background winds and temperature by spectral broadening The presentation is about the design and development of Incoherent Doppler lidar to obtain wind information in the height regions of 30-65 km The paper analyses and describes various types of techniques that can be adopted viz Edge technique and Fringe Imaging technique The paper brings out the scientific objectives configuration simulations error sources and technical challenges involved in the development of Rayleigh Doppler lidar The presentation also gives a novel technique for calibrating the lidar

  1. Design of channel experiment equipment for measuring coolant velocity of innovative research reactor

    International Nuclear Information System (INIS)

    Muhammad Subekti; Endiah Puji Hastuti; Dedi Heriyanto

    2014-01-01

    The design of innovative high flux research reactor (RRI) requires high power so that the capability core cooling requires to be improved by designing the faster core coolant velocity near to the critical velocity limit. Hence, the critical coolant velocity as the one of the important parameter of the reactor safety shall be measured by special equipment to the velocity limit that may induce fuel element degradation. The research aims is to calculate theoretically the critical coolant velocity and to design the special experiment equipment namely EXNal for measuring the critical coolant velocity in fuel element subchannel of the RRI. EXNal design considers the critical velocity calculation result of 20.52 m/s to determine the variation of flow rate of 4.5-29.2 m 3 /h, in which the experiment could simulate the 1-4X standard coolant velocity of RSG-GAS as well as destructive test of RRI's fuel plate. (author)

  2. 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.

  3. 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.

  4. Aortic pulse wave velocity measurement in systemic sclerosis patients

    Directory of Open Access Journals (Sweden)

    M. Sebastiani

    2012-12-01

    Full Text Available Background. Systemic sclerosis (SSc is characterized by endothelial dysfunction and widespread microangiopathy. However, a macrovascular damage could be also associated. Aortic pulse wave velocity (aPWV is known to be a reliable indicator of arterial stiffness and a useful prognostic predictor of cardiovascular events. Moreover, aPWV may be easily measured by non-invasive, user-friendly tool. Aim of our study was to evaluate aPWV alterations in a series of SSc patients. Methods. The aPWV was evaluated in 35 consecutive female SSc patients and 26 sex- and age-matched healthy controls. aPWV alterations were correlated with cardiopulmonary involvement. Results. A significant increase of aPWV was observed in SSc patients compared to controls (9.4±3.2 m/s vs 7.3±1 m/s; P=0.002. In particular, 14/35 (40% SSc patients and only 1/26 (4% controls (P=0.0009 showed increased aPWV (>9 m/s cut-off value. Moreover, echocardiography evaluation showed an increased prevalence of right atrial and ventricular dilatation (atrial volume: 23.6±6.2 mL vs 20.3±4.3 mL, P=0.026; ventricular diameter 19.5±4.9 mm vs 15.9±1.6 mm; P=0.001 associated to higher values of pulmonary arterial systolic pressure (PAPs in SSc patients (31.5±10.4 mmHg vs 21.6±2.9 mmHg; P50 years old. Furthermore, altered aPWV was more frequently associated with limited cutaneous pattern, longer disease duration (≥5 years, and/or presence of anticentromere antibody (ACA. Conclusions. A significantly higher prevalence of abnormally increased aPWV was evidenced in SSc patients compared to healthy controls. The possibility of more pronounced and diffuse vascular damage in a particular SSc subset (ACA-positive subjects with limited cutaneous scleroderma and longer disease duration might be raised.

  5. Method of measuring directed electron velocities in flowing plasma using the incoherent regions of laser scattering

    International Nuclear Information System (INIS)

    Jacoby, B.A.; York, T.M.

    1979-02-01

    With the presumption that a shifted Maxwellian velocity distribution adequately describes the electrons in a flowing plasma, the details of a method to measure their directed velocity are described. The system consists of a ruby laser source and two detectors set 180 0 from each other and both set at 90 0 with respect to the incident laser beam. The lowest velocity that can be determined by this method depends on the electron thermal velocity. The application of this diagnostic to the measurement of flow velocities in plasma being lost from the ends of theta-pinch devices is described

  6. Spatial averaging of streamwise and spanwise velocity measurements in wall-bounded turbulence using ∨- and ×-probes

    International Nuclear Information System (INIS)

    Philip, Jimmy; Baidya, Rio; Hutchins, Nicholas; Monty, Jason P; Marusic, Ivan

    2013-01-01

    (more precisely on the two-point correlations) and the measured means depend only on the unfiltered mean. The various results are found to be in accordance with the experimental measurements carried out in a turbulent boundary layer at Re τ ≈ 5000. Finally, considering the physical positioning of wires in the ∨- and ×-probes combined with the above results suggests that ×-probes might be more suitable for stream–spanwise velocity measurements than the ∨-probes in conventional wind tunnels. (paper)

  7. Direct measurement technique for shock wave velocity with irradiation drive

    International Nuclear Information System (INIS)

    Wang Feng; Peng Xiaoshi; Liu Shenye; Jiang Xiaohua; Ding Yongkun

    2011-01-01

    According to the ionization mechanism of transparent material under super high pressure, the direct diagnosis method of shock wave has been analyzed. With the Drude free electron model, the reflectivity difference of shock wave front under different pressures was analyzed. The blank effect in the detector was studied, which is caused by the X-ray ionization of transparent material, after analyzing the reflectivity data in space-time scale. The experiment shows that the beginning point and duration of blank effect are consistent with the start point and duration of laser pulse, respectively. And the reflectivity of shock wave front is about 35% when the shock velocity is 32 km/s. The reason and solution for blank effect was presented. The formula to calculate the shock wave velocity in transparent material was also deduced and verified. (authors)

  8. Three-dimensional instantaneous velocity field measurement using ...

    Indian Academy of Sciences (India)

    2014-02-13

    Feb 13, 2014 ... Abstract. In the present study, a digital holography microscope has been developed to study instantaneous 3D velocity field in a square channel of 1000 × 1000 μm2 cross-section. The flow field is seeded with polystyrene microspheres of size dp = 2.1 μm. The volumetric flow rate is set equal to 20 μl/min.

  9. Effects of non-Maxwellian electron velocity distribution functions and nonspherical geometry on minor ions in the solar wind

    Science.gov (United States)

    Burgi, A.

    1987-01-01

    A previous model has shown that in order to account for the charge state distribution in the low-speed solar wind, a high coronal temperature is necessary and that this temperature peak goes together with a peak of nx/np in the corona. In the present paper, one of the assumptions made previously, i.e., that coronal electrons are Maxwellian, is relaxed, and a much cooler model is presented, which could account for the same oxygen charge states in the solar wind due to the inclusion of non-Maxwellian electrons. Also, due to a different choice of the coronal magnetic field geometry, this model would show no enhancement of the coronal nx/np. Results of the two models are then compared, and observational tests to distinguish between the two scenarios are proposed: comparison of directly measured coronal Te to charge state measurements in the solar wind, determination of the coronal nx/np measurement of ion speeds in the acceleration region of the solar wind, and measurement of the frozen-in silicon charge state distribution.

  10. Measurement of Off-Body Velocity, Pressure, and Temperature in an Unseeded Supersonic Air Vortex by Stimulated Raman Scattering

    Science.gov (United States)

    Herring, Gregory C.

    2008-01-01

    A noninvasive optical method is used to make time-averaged (30 sec) off-body measurements in a supersonic airflow. Seeding of tracer particles is not required. One spatial component of velocity, static pressure, and static temperature are measured with stimulated Raman scattering. The three flow parameters are determined simultaneously from a common sample volume (0.3 by 0.3 by 15 mm) using concurrent measurements of the forward and backward scattered line shapes of a N2 vibrational Raman transition. The capability of this technique is illustrated with laboratory and large-scale wind tunnel testing that demonstrate 5-10% measurement uncertainties. Because the spatial resolution of the present work was improved to 1.5 cm (compared to 20 cm in previous work), it was possible to demonstrate a modest one-dimensional profiling of cross-flow velocity, pressure, and translational temperature through the low-density core of a stream-wise vortex (delta-wing model at Mach 2.8 in NASA Langley's Unitary Plan Wind Tunnel).

  11. The role of wind field induced flow velocities in destratification and hypoxia reduction at Meiling Bay of large shallow Lake Taihu, China.

    Science.gov (United States)

    Jalil, Abdul; Li, Yiping; Du, Wei; Wang, Wencai; Wang, Jianwei; Gao, Xiaomeng; Khan, Hafiz Osama Sarwar; Pan, Baozhu; Acharya, Kumud

    2018-01-01

    Wind induced flow velocity patterns and associated thermal destratification can drive to hypoxia reduction in large shallow lakes. The effects of wind induced hydrodynamic changes on destratification and hypoxia reduction were investigated at the Meiling bay (N 31° 22' 56.4″, E 120° 9' 38.3″) of Lake Taihu, China. Vertical flow velocity profile analysis showed surface flow velocities consistency with the wind field and lower flow velocity profiles were also consistent (but with delay response time) when the wind speed was higher than 6.2 m/s. Wind field and temperature found the control parameters for hypoxia reduction and for water quality conditions at the surface and bottom profiles of lake. The critical temperature for hypoxia reduction at the surface and the bottom profile was ≤24.1C° (below which hypoxic conditions were found reduced). Strong prevailing wind field (onshore wind directions ESE, SE, SSE and E, wind speed ranges of 2.4-9.1 m/s) reduced the temperature (22C° to 24.1C°) caused reduction of hypoxia at the near surface with a rise in water levels whereas, low to medium prevailing wind field did not supported destratification which increased temperature resulting in increased hypoxia. Non-prevailing wind directions (offshore) were not found supportive for the reduction of hypoxia in study area due to less variable wind field. Daytime wind field found more variable (as compared to night time) which increased the thermal destratification during daytime and found supportive for destratification and hypoxia reduction. The second order exponential correlation found between surface temperature and Chlorophyll-a (R 2 : 0.2858, Adjusted R-square: 0.2144 RMSE: 4.395), Dissolved Oxygen (R 2 : 0.596, Adjusted R-square: 0.5942, RMSE: 0.3042) concentrations. The findings of the present study reveal the driving mechanism of wind induced thermal destratification and hypoxic conditions, which may further help to evaluate the wind role in eutrophication

  12. Bulk velocity measurements by video analysis of dye tracer in a macro-rough channel

    International Nuclear Information System (INIS)

    Ghilardi, T; Franca, M J; Schleiss, A J

    2014-01-01

    Steep mountain rivers have hydraulic and morphodynamic characteristics that hinder velocity measurements. The high spatial variability of hydraulic parameters, such as water depth (WD), river width and flow velocity, makes the choice of a representative cross-section to measure the velocity in detail challenging. Additionally, sediment transport and rapidly changing bed morphology exclude the utilization of standard and often intrusive velocity measurement techniques. The limited technical choices are further reduced in the presence of macro-roughness elements, such as large, relatively immobile boulders. Tracer tracking techniques are among the few reliable methods that can be used under these conditions to evaluate the mean flow velocity. However, most tracer tracking techniques calculate bulk flow velocities between two or more fixed cross-sections. In the presence of intense sediment transport resulting in an important temporal variability of the bed morphology, dead water zones may appear in the few selected measurement sections. Thus a technique based on the analysis of an entire channel reach is needed in this study. A dye tracer measurement technique in which a single camcorder visualizes a long flume reach is described and developed. This allows us to overcome the problem of the presence of dead water zones. To validate this video analysis technique, velocity measurements were carried out on a laboratory flume simulating a torrent, with a relatively gentle slope of 1.97% and without sediment transport, using several commonly used velocity measurement instruments. In the absence of boulders, salt injections, WD and ultrasonic velocity profiler measurements were carried out, along with dye injection technique. When boulders were present, dye tracer technique was validated only by comparison with salt tracer. Several video analysis techniques used to infer velocities were developed and compared, showing that dye tracking is a valid technique for bulk velocity

  13. Measured wind speed trends on the west coast of Canada

    Science.gov (United States)

    Tuller, Stanton E.

    2004-09-01

    Trends in measured wind speed are discussed for four stations on the west coast of Canada. Periods of record vary with the station. They begin in the late 1940s or the 1950s and run through to the early to mid 1990s. The most prominent feature of the time series was a decline in mean annual and winter wind speeds at Cape St James, Victoria International Airport, and Vancouver International Airport during the middle portion of the record. Declines in mean annual wind speed are matched by increases in the percentage of calms and decreases in high wind speed observations. The pressure gradient between Victoria, Vancouver and Comox, the Pacific North American index, the Pacific decadal oscillation index, and other climate elements in British Columbia and the northwestern USA show trends at roughly the same time, indicating a natural cause of the wind speed decrease. Comox Airport mean wind speeds increased, however, perhaps the result of reduced friction in the vicinity of the anemometer outweighing the decrease in the regional pressure gradient.

  14. Thermal effects influencing measurements in a supersonic blowdown wind tunnel

    Directory of Open Access Journals (Sweden)

    Vuković Đorđe S.

    2016-01-01

    Full Text Available During a supersonic run of a blowdown wind tunnel, temperature of air in the test section drops which can affect planned measurements. Adverse thermal effects include variations of the Mach and Reynolds numbers, variation of airspeed, condensation of moisture on the model, change of characteristics of the instrumentation in the model, et cetera. Available data on thermal effects on instrumentation are pertaining primarily to long-run-duration wind tunnel facilities. In order to characterize such influences on instrumentation in the models, in short-run-duration blowdown wind tunnels, temperature measurements were made in the wing-panel-balance and main-balance spaces of two wind tunnel models tested in the T-38 wind tunnel. The measurements showed that model-interior temperature in a run increased at the beginning of the run, followed by a slower drop and, at the end of the run, by a large temperature drop. Panel-force balance was affected much more than the main balance. Ways of reducing the unwelcome thermal effects by instrumentation design and test planning are discussed.

  15. Comparison of NWP wind speeds and directions to measured wind speeds and directions

    DEFF Research Database (Denmark)

    Astrup, Poul; Mikkelsen, Torben

    Numerical Weather Predictions (NWP) of wind speed and direction has been compared to measurements for seven German sites for nuclear power plants, and for Risø, the site of the Danish nuclear research reactors now being decommissioned . For the German sites the data cover approximately three month...

  16. Quality controls for wind measurement of a 1290-MHz boundary layer profiler under strong wind conditions.

    Science.gov (United States)

    Liu, Zhao; Zheng, Chaorong; Wu, Yue

    2017-09-01

    Wind profilers have been widely adopted to observe the wind field information in the atmosphere for different purposes. But accuracy of its observation has limitations due to various noises or disturbances and hence need to be further improved. In this paper, the data measured under strong wind conditions, using a 1290-MHz boundary layer profiler (BLP), are quality controlled via a composite quality control (QC) procedure proposed by the authors. Then, through the comparison with the data measured by radiosonde flights (balloon observations), the critical thresholds in the composite QC procedure, including consensus average threshold T 1 and vertical shear threshold T 3 , are systematically discussed. And the performance of the BLP operated under precipitation is also evaluated. It is found that to ensure the high accuracy and high data collectable rate, the optimal range of subsets is determined to be 4 m/s. Although the number of data rejected by the combined algorithm of vertical shear examination and small median test is quite limited, it is proved that the algorithm is quite useful to recognize the outlier with a large discrepancy. And the optimal wind shear threshold T 3 can be recommended as 5 ms -1 /100m. During patchy precipitation, the quality of data measured by the four oblique beams (using the DBS measuring technique) can still be ensured. After the BLP data are quality controlled by the composite QC procedure, the output can show good agreement with the balloon observation.

  17. Offshore Wind Turbine Foundation Model Validation with Wind Farm Measurements and Uncertainty Quantification

    DEFF Research Database (Denmark)

    Koukoura, Christina; Natarajan, Anand; Krogh, Thomas

    2013-01-01

    The variation in simulated monopile substructure loads is quantified by validating an aero-hydro-servo-elastic design tool with offshore foundation load measurements. A three bladed 3.6MW pitch controlled variable speed wind turbine for offshore monopile foundations is modeled in the HAWC2...

  18. MR flow velocity measurement using 2D phase contrast, assessment of imaging parameters

    International Nuclear Information System (INIS)

    Akata, Soichi; Fukushima, Akihiro; Abe, Kimihiko; Darkanzanli, A.; Gmitro, A.F.; Unger, E.C.; Capp, M.P.

    1999-01-01

    The two-dimensional (2D) phase contrast technique using balanced gradient pulses is utilized to measure flow velocities of cerebrospinal fluid and blood. Various imaging parameters affect the accuracy of flow velocity measurements to varying degrees. Assessment of the errors introduced by changing the imaging parameters are presented and discussed in this paper. A constant flow phantom consisting of a pump, a polyethylene tube and a flow meter was assembled. A clinical 1.5 Tesla MR imager was used to perform flow velocity measurements. The phase contrast technique was used to estimate the flow velocity of saline through the phantom. The effects of changes in matrix size, flip angle, flow compensation, and velocity encoding (VENC) value were tested in the pulse sequence. Gd-DTPA doped saline was used to study the effect of changing T1 on the accuracy of flow velocity measurement. Matrix size (within practical values), flip angle, and flow compensation had minimum impact on flow velocity measurements. T1 of the solution also had no effect on the accuracy of measuring the flow velocity. On the other hand, it was concluded that errors as high as 20% can be expected in the flow velocity measurements if the VENC value is not properly chosen. (author)

  19. MR flow velocity measurement using 2D phase contrast, assessment of imaging parameters

    Energy Technology Data Exchange (ETDEWEB)

    Akata, Soichi; Fukushima, Akihiro; Abe, Kimihiko [Tokyo Medical Coll. (Japan); Darkanzanli, A.; Gmitro, A.F.; Unger, E.C.; Capp, M.P.

    1999-11-01

    The two-dimensional (2D) phase contrast technique using balanced gradient pulses is utilized to measure flow velocities of cerebrospinal fluid and blood. Various imaging parameters affect the accuracy of flow velocity measurements to varying degrees. Assessment of the errors introduced by changing the imaging parameters are presented and discussed in this paper. A constant flow phantom consisting of a pump, a polyethylene tube and a flow meter was assembled. A clinical 1.5 Tesla MR imager was used to perform flow velocity measurements. The phase contrast technique was used to estimate the flow velocity of saline through the phantom. The effects of changes in matrix size, flip angle, flow compensation, and velocity encoding (VENC) value were tested in the pulse sequence. Gd-DTPA doped saline was used to study the effect of changing T1 on the accuracy of flow velocity measurement. Matrix size (within practical values), flip angle, and flow compensation had minimum impact on flow velocity measurements. T1 of the solution also had no effect on the accuracy of measuring the flow velocity. On the other hand, it was concluded that errors as high as 20% can be expected in the flow velocity measurements if the VENC value is not properly chosen. (author)

  20. Analysis of Mexico wind tunnel measurements

    DEFF Research Database (Denmark)

    Schepers, J.G.; Boorsma, K.; Cho, T.

    This report describes the work performed within the first phase of IEA Task 29 Mexnext. In this IEA Task 29 a total of 20 organisations from 11 different countries collaborated in analysing the measurements which have been taken in the EU project ‘Mexico’. Within this Mexico project 9 European...

  1. An improvement of wind velocity estimation from radar Doppler spectra in the upper mesosphere

    Directory of Open Access Journals (Sweden)

    S. Takeda

    2001-08-01

    Full Text Available We have developed a new parameter estimation method for Doppler wind spectra in the mesosphere observed with an MST radar such as the MU radar in the DBS (Doppler Beam Swinging mode. Off-line incoherent integration of the Doppler spectra is carried out with a new algorithm excluding contamination by strong meteor echoes. At the same time, initial values on a least square fitting of the Gaussian function are derived using a larger number of integration of the spectra for a longer time and for multiple heights. As a result, a significant improvement has been achieved with the probability of a successful fitting and parameter estimation above 80 km. The top height for the wind estimation has been improved to around 95 km. A comparison between the MU radar and the High Resolution Doppler Imager (HRDI on the UARS satellite is shown and the capability of the new method for a validation of a future satellite mission is suggested.Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics – Radio science (remote sensing; signal processing

  2. Wind Tunnel Measurements of Turbulent Boundary Layer over Hypothetical Urban Roughness Elements

    Science.gov (United States)

    Ho, Y. K.; Liu, C. H.

    2012-04-01

    Urban morphology affects the near-ground atmospheric boundary layer that in turn modifies the wind flows and pollutant dispersion over urban areas. A number of numerical models (large-eddy simulation, LES and k-ɛ turbulence models) have been developed to elucidate the transport processes in and above urban street canyons. To complement the modelling results, we initiated a wind tunnel study to examine the influence of idealized urban roughness on the flow characteristics and pollutant dispersion mechanism over 2D idealized street canyons placed in cross flows. Hot-wire anemometry (HWA) was employed in this study to measure the flows over 2D street canyons in the wind tunnel in our university. Particular focus in the beginning stage was on the fabrication of hot-wire probes, data acquisition system, and signal processing technique. Employing the commonly adopted hot-wire universal function, we investigated the relationship in between and developed a scaling factor which could generalize the output of our hot-wire probes to the standardized one as each hot-wire probes has its unique behaviour. Preliminary experiments were performed to measure the wind flows over street canyons of unity aspect ratio. Vertical profiles of the ensemble average velocity and fluctuations at three different segments over the street canyons were collected. The results were then compared with our LES that show a good argument with each other. Additional experiments are undertaken to collect more data in order to formulate the pollutant dispersion mechanism of street canyons and urban areas.

  3. CFD modelling approaches against single wind turbine wake measurements using RANS

    International Nuclear Information System (INIS)

    Stergiannis, N; Lacor, C; Beeck, J V; Donnelly, R

    2016-01-01

    Numerical simulations of two wind turbine generators including the exact geometry of their blades and hub are compared against a simplified actuator disk model (ADM). The wake expansion of the upstream rotor is investigated and compared with measurements. Computational Fluid Dynamics (CFD) simulations have been performed using the open-source platform OpenFOAM [1]. The multiple reference frame (MRF) approach was used to model the inner rotating reference frames in a stationary computational mesh and outer reference frame for the full wind turbine rotor simulations. The standard k — ε and k — ω turbulence closure schemes have been used to solve the steady state, three dimensional Reynolds Averaged Navier- Stokes (RANS) equations. Results of near and far wake regions are compared with wind tunnel measurements along three horizontal lines downstream. The ADM under-predicted the velocity deficit at the wake for both turbulence models. Full wind turbine rotor simulations showed good agreement against the experimental data at the near wake, amplifying the differences between the simplified models. (paper)

  4. Functional analysis of third ventriculostomy patency with phase-contrast MRI velocity measurements

    International Nuclear Information System (INIS)

    Lev, S.; Bhadelia, R.A.; Estin, D.; Heilman, C.B.; Wolpert, S.M.

    1997-01-01

    Our purpose was to explore the utility of cine phase-contrast MRI velocity measurements in determining the functional status of third ventriculostomies, and to correlate the quantitative velocity data with clinical follow-up. We examined six patients with third ventriculostomies and 12 normal subjects by phase-contrast MRI. The maximum craniocaudal to maximum caudocranial velocity range was measured at regions of interest near the third ventricular floor, and in cerebrospinal fluid anterior to the upper pons and spinal cord on midline sagittal images. Ratios of the velocities of both the third ventricle and prepontine space to the space anterior to the spinal cord were obtained. The velocities near the third ventricular floor and in the pontine cistern were significantly higher in patients than in normal subjects, but the velocity anterior to the spinal cord was similar between the groups. The velocity ratios, used to normalize individual differences, were also higher in patients than in controls. Two patients had lower velocity ratios than their fellows at the third ventricular floor and in the pontine cistern; one required a shunt 11 months later, while in the other, who had a third ventricular/thalamic tumor, the lower values probably reflect distortion of the third ventricular floor. We conclude that phase-contrast MR velocity measurements, specifically the velocity ratio between the high pontine cistern and the space anterior to the spinal cord, can help determine the functional status of third ventriculostomies. (orig.)

  5. Evaporation of Arabian light crude oil spilled on sea and on beach sands : influence of solar radiation and wind velocity

    International Nuclear Information System (INIS)

    Bergueiro, J.R.; Marti, A.; Fuertes, A.; Moreno, S.; Guijarro, S.

    1998-01-01

    The evaporation of crude oil resulting from a spill on sea water was studied to develop a simulation model. Evaporation takes place within a complex process of mass and energy transfer. The effects of physical and chemical variables (such as wind velocity and direct and diffused solar radiation) and the environmental conditions of the spillage were also considered. Arabian crude oil was used in the simulation model for crude oil spillage on sea water. An equation for the evaporation process was used to correlate the evaporated fraction of oil as a function of time. The area of spreading was determined as a function of the dominant stage at each moment of spreading. The evaporation of spilled crude oil on beach sand consisting of three different particle sizes was also studied and used for a simulation model for crude oil spillage on a polluted beach. 7 refs., 6 tabs., 10 figs

  6. A new wind vane for the measurement of atmospheric turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Parker, M.J.; Heverly, M.

    1997-02-01

    A Cooperative Research and Development Agreement (CRADA) between Met One Instruments, Incorporated (Met One) and Westinghouse Savannah River Company (WSRC) was created to develop a new wind vane that more accurately measures atmospheric turbulence. Through a process that had several phases, Met One created a prototype vane that was designed to attach to the existing Model 1585 Bi-Directional Wind Vane instrument structure. The prototype contained over 20% less mass to enhance responsiveness, which was also increased through the use of a teardrop-shaped fin structure. The prototype vane can be readily manufactured for commercial retail. Tests in wind tunnel of Building 735-7A, the Meteorological Engineering Facility, indicated that the new vane has a superior starting threshold of less than 0.14 meter per second, a delay distance of 0.72 meter, and a damping ratio of 0.4. The relative accuracy of less than one degree is unchanged from the previous design. The vane bias was acceptable at 0.8 degree for the horizontal wind angle, but was slightly high at 1.4 degree for the verticle wind angle. The high value of the verticle wind angle bias can most likely be reduced to the desired less than one degree value with standard manufacturing production techniques. The durability of the prototype vane was not tested in the field but is expected to be slightly less due to the use of hollow rather than foam-filled fins. However, the loss of some durability is more than compensated with increased sensitivity at low wind speeds. Field testing of the prototype is required to test for adequacy of durability.

  7. High resolution wind turbine wake measurements with a scanning lidar

    DEFF Research Database (Denmark)

    Herges, T. G.; Maniaci, D. C.; Naughton, B. T.

    2017-01-01

    High-resolution lidar wake measurements are part of an ongoing field campaign being conducted at the Scaled Wind Farm Technology facility by Sandia National Laboratories and the National Renewable Energy Laboratory using a customized scanning lidar from the Technical University of Denmark. One...

  8. Water vapour and wind measurements by a two micron space lidar

    Science.gov (United States)

    Ghibaudo, J.-B.; Labandibar, J.-Y.

    2018-04-01

    AEROSPATIALE presents the main results of the feasibility study under ESA contract on a coherent 2μm lidar instrument capable of measuring water vapour and wind velocity in the planetary boundary layer. The selected instrument configuration and the associated performance are provided, and the main critical subsystems identified (laser configuration, coherent receiver chain architecture, frequency locking and offsetting architecture. The second phase of this study is dedicated to breadboard the most critical elements of such an instrument in order to technologically consolidate its feasibility.

  9. A Measuring Method About the Bullet Velocity in Electromagnetic Rail Gun

    Directory of Open Access Journals (Sweden)

    Jianming LIU

    2014-02-01

    Full Text Available The operating principle of electromagnetic rail gun by store capacitor was analyzed. A simulation model about the bullet velocity in the electromagnetic rail gun was built. The results of computer simulation experiment showed the relationships between the bullet velocity and the capacitor charging voltage and the pellet mass. By ten coil targets, a new kind of measuring method for the bullet velocity in electromagnetic rail gun was presented. The results of the actual experiment were analyzed. The improving method for measuring bullet velocity was put forward.

  10. MEASUREMENT OF WIND SPEED FROM COOLING LAKE THERMAL IMAGERY

    International Nuclear Information System (INIS)

    Garrett, A.; Kurzeja, R.; Villa-Aleman, E.; Tuckfield, C.; Pendergast, M.

    2009-01-01

    The Savannah River National Laboratory (SRNL) collected thermal imagery and ground truth data at two commercial power plant cooling lakes to investigate the applicability of laboratory empirical correlations between surface heat flux and wind speed, and statistics derived from thermal imagery. SRNL demonstrated in a previous paper (1] that a linear relationship exists between the standard deviation of image temperature and surface heat flux. In this paper, SRNL will show that the skewness of the temperature distribution derived from cooling lake thermal images correlates with instantaneous wind speed measured at the same location. SRNL collected thermal imagery, surface meteorology and water temperatures from helicopters and boats at the Comanche Peak and H. B. Robinson nuclear power plant cooling lakes. SRNL found that decreasing skewness correlated with increasing wind speed, as was the case for the laboratory experiments. Simple linear and orthogonal regression models both explained about 50% of the variance in the skewness - wind speed plots. A nonlinear (logistic) regression model produced a better fit to the data, apparently because the thermal convection and resulting skewness are related to wind speed in a highly nonlinear way in nearly calm and in windy conditions

  11. High spectral resolution lidar based on quad mach zehnder interferometer for aerosols and wind measurements on board space missions

    Directory of Open Access Journals (Sweden)

    Mariscal Jean-François

    2018-01-01

    Full Text Available We present the measurement principle and the optical design of a Quad Mach Zehnder (QMZ interferometer as HSRL technique, allowing simultaneous measurements of particle backscattering and wind velocity. Key features of this concept is to operate with a multimodal laser and do not require any frequency stabilization. These features are relevant especially for space applications for which high technical readiness level is required.

  12. Prerequisites for Accurate Monitoring of River Discharge Based on Fixed-Location Velocity Measurements

    Science.gov (United States)

    Kästner, K.; Hoitink, A. J. F.; Torfs, P. J. J. F.; Vermeulen, B.; Ningsih, N. S.; Pramulya, M.

    2018-02-01

    River discharge has to be monitored reliably for effective water management. As river discharge cannot be measured directly, it is usually inferred from the water level. This practice is unreliable at places where the relation between water level and flow velocity is ambiguous. In such a case, the continuous measurement of the flow velocity can improve the discharge prediction. The emergence of horizontal acoustic Doppler current profilers (HADCPs) has made it possible to continuously measure the flow velocity. However, the profiling range of HADCPs is limited, so that a single instrument can only partially cover a wide cross section. The total discharge still has to be determined with a model. While the limitations of rating curves are well understood, there is not yet a comprehensive theory to assess the accuracy of discharge predicted from velocity measurements. Such a theory is necessary to discriminate which factors influence the measurements, and to improve instrument deployment as well as discharge prediction. This paper presents a generic method to assess the uncertainty of discharge predicted from range-limited velocity profiles. The theory shows that a major source of error is the variation of the ratio between the local and cross-section-averaged velocity. This variation is large near the banks, where HADCPs are usually deployed and can limit the advantage gained from the velocity measurement. We apply our theory at two gauging stations situated in the Kapuas River, Indonesia. We find that at one of the two stations the index velocity does not outperform a simple rating curve.

  13. Measurement of thermal plasma jet temperature and velocity by laser light lineshape analysis

    International Nuclear Information System (INIS)

    Snyder, S.C.; Reynolds, L.D.

    1991-01-01

    Two important parameters of thermal plasma jets are kinetic or gas temperatures and flow velocity. Gas temperatures have been traditionally measured using emission spectroscopy, but this method depends on either the generally unrealistic assumption of the existence of local thermodynamic equilibrium (LTE) within the plasma, or the use of various non-LTE or partial LTE models to relate the intensity of the emission lines to the gas temperature. Plasma jet velocities have been measured using laser Doppler velocimetry on particles injected into the plasma. However, this method is intrusive and it is not known how well the particle velocities represent the gas velocity. Recently, plasma jet velocities have been measured from the Doppler shift of laser light scattered by the plasma. In this case, the Doppler shift was determined from the difference in the transmission profile of a high resolution monochromator between red shifted and blue shifted scattered light. A direct approach to measuring localized temperatures and velocities is afforded by high resolution scattered light lineshape measurements. The linewidth of laser light scattered by atoms and ions can be related to the kinetic temperature without LTE assumptions, while a shift in the peak position relative to the incident laser lineshape yields the gas velocity. We report in this paper work underway to measure gas temperatures and velocities in an argon thermal plasma jet using high resolution lineshape analysis of scattered laser light

  14. Temperature Field-Wind Velocity Field Optimum Control of Greenhouse Environment Based on CFD Model

    Directory of Open Access Journals (Sweden)

    Yongbo Li

    2014-01-01

    Full Text Available The computational fluid dynamics technology is applied as the environmental control model, which can include the greenhouse space. Basic environmental factors are set to be the control objects, the field information is achieved via the division of layers by height, and numerical characteristics of each layer are used to describe the field information. Under the natural ventilation condition, real-time requirements, energy consumption, and distribution difference are selected as index functions. The optimization algorithm of adaptive simulated annealing is used to obtain optimal control outputs. A comparison with full-open ventilation shows that the whole index can be reduced at 44.21% and found that a certain mutual exclusiveness exists between the temperature and velocity field in the optimal course. All the results indicate that the application of CFD model has great advantages to improve the control accuracy of greenhouse.

  15. Measurement of core velocity fluctuations and the dynamo in a reversed-field pinch

    International Nuclear Information System (INIS)

    Den Hartog, D.J.; Craig, D.; Fiksel, G.; Fontana, P.W.; Prager, S.C.; Sarff, J.S.; Chapman, J.T.

    1998-01-01

    Plasma flow velocity fluctuations have been directly measured in the high temperature magnetically confined plasma in the Madison Symmetric Torus (MST) Reversed-Field Pinch (RFP). These measurements show that the flow velocity fluctuations are correlated with magnetic field fluctuations. This initial measurement is subject to limitations of spatial localization and other uncertainties, but is evidence for sustainment of the RFP magnetic field configuration by the magnetohydrodynamic (MHD) dynamo. Both the flow velocity and magnetic field fluctuations are the result of global resistive MHD modes of helicity m = 1, n = 5--10 in the core of MST. Chord-averaged flow velocity fluctuations are measured in the core of MST by recording the Doppler shift of impurity line emission with a specialized high resolution and throughput grating spectrometer. Magnetic field fluctuations are recorded with a large array of small edge pickup coils, which allows spectral decomposition into discrete modes and subsequent correlation with the velocity fluctuation data

  16. Determination of the thermospheric neutral wind from incoherent scatter radar measurements

    International Nuclear Information System (INIS)

    Haeggstroem, I.; Murdin, J.; Rees, D.

    1984-11-01

    Measurements made by the EISCAT UHF incoherent scatter radar are used to derive thermospheric winds. The derived wind is compared to Fabry-Perot interferometer measurements of the neutral wind made simultaneously. The uncertainties in the radar derived wind are discussed. (author)

  17. Measurement campaign for wind power potential in west Greenland

    Science.gov (United States)

    Rønnow Jakobsen, Kasper

    2013-04-01

    . During the first years, the influence of instrument icing was not considered, but recently one of the sites was equipped with an ice rate sensor and a heated ultrasonic anemometer to study the ice influence. 3 Results The predominant wind direction for most sites is away from the ice cap at the center of the continent, but for some coastal sites it is north or south. The north-south wind pattern is expected from the synoptic patterns and the barrier effect of the ice cap. The sites where the predominant wind direction is away from the inland ice are dominated by katabatic wind systems from the ice cap and form valley systems. These sites also seem to have the highest wind resource and will be studied further. A good example of the influence of katabatic and thermal wind systems can be seen in the measurement data from Sarfannguit and Nanortalik 66 and 60 degrees northern latitude respectively. In future work, these katabatic flows and their impact on the wind resource will be studied using mesoscale modelling and microscale downscaling.

  18. The Skipheia Wind Measurement Station. Instrumentation, Wind Speed Profiles and Turbulence Spectra

    Energy Technology Data Exchange (ETDEWEB)

    Aasen, S E

    1995-10-01

    This thesis describes the design of a measurement station for turbulent wind and presents results from an analysis of the collected data. The station is located at Skipheia near the south-west end of Froeya, an island off the coast of Mid-Norway. The station is unique for studies of turbulent winds because of the large numbers of sensors, which are located at various heights above ground up to 100 m, a sampling rate of 0.85 Hz and storage of the complete time series. The frequency of lightning and atmospheric discharges to the masts are quite high and much effort has gone into minimizing the damage caused by lightning activity. A major part of the thesis deals with data analysis and modelling. There are detailed discussions on the various types of wind sensors and their calibration, the data acquisition system and operating experiences with it, the database, data quality control, the wind speed profile and turbulence. 40 refs., 78 figs., 17 tabs.

  19. Velocity Deficits in the Wake of Model Lemon Shark Dorsal Fins Measured with Particle Image Velocimetry

    Science.gov (United States)

    Terry, K. N.; Turner, V.; Hackett, E.

    2017-12-01

    Aquatic animals' morphology provides inspiration for human technological developments, as their bodies have evolved and become adapted for efficient swimming. Lemon sharks exhibit a uniquely large second dorsal fin that is nearly the same size as the first fin, the hydrodynamic role of which is unknown. This experimental study looks at the drag forces on a scale model of the Lemon shark's unique two-fin configuration in comparison to drag forces on a more typical one-fin configuration. The experiments were performed in a recirculating water flume, where the wakes behind the scale models are measured using particle image velocimetry. The experiments are performed at three different flow speeds for both fin configurations. The measured instantaneous 2D distributions of the streamwise and wall-normal velocity components are ensemble averaged to generate streamwise velocity vertical profiles. In addition, velocity deficit profiles are computed from the difference between these mean streamwise velocity profiles and the free stream velocity, which is computed based on measured flow rates during the experiments. Results show that the mean velocities behind the fin and near the fin tip are smallest and increase as the streamwise distance from the fin tip increases. The magnitude of velocity deficits increases with increasing flow speed for both fin configurations, but at all flow speeds, the two-fin configurations generate larger velocity deficits than the one-fin configurations. Because the velocity deficit is directly proportional to the drag force, these results suggest that the two-fin configuration produces more drag.

  20. High Precision UTDR Measurements by Sonic Velocity Compensation with Reference Transducer

    Directory of Open Access Journals (Sweden)

    Sam Stade

    2014-07-01

    Full Text Available An ultrasonic sensor design with sonic velocity compensation is developed to improve the accuracy of distance measurement in membrane modules. High accuracy real-time distance measurements are needed in membrane fouling and compaction studies. The benefits of the sonic velocity compensation with a reference transducer are compared to the sonic velocity calculated with the measured temperature and pressure using the model by Belogol’skii, Sekoyan et al. In the experiments the temperature was changed from 25 to 60 °C at pressures of 0.1, 0.3 and 0.5 MPa. The set measurement distance was 17.8 mm. Distance measurements with sonic velocity compensation were over ten times more accurate than the ones calculated based on the model. Using the reference transducer measured sonic velocity, the standard deviations for the distance measurements varied from 0.6 to 2.0 µm, while using the calculated sonic velocity the standard deviations were 21–39 µm. In industrial liquors, not only the temperature and the pressure, which were studied in this paper, but also the properties of the filtered solution, such as solute concentration, density, viscosity, etc., may vary greatly, leading to inaccuracy in the use of the Belogol’skii, Sekoyan et al. model. Therefore, calibration of the sonic velocity with reference transducers is needed for accurate distance measurements.

  1. A simple measuring technique of surface flow velocity to analyze the behavior of velocity fields in hydraulic engineering applications.

    Science.gov (United States)

    Tellez, Jackson; Gomez, Manuel; Russo, Beniamino; Redondo, Jose M.

    2015-04-01

    An important achievement in hydraulic engineering is the proposal and development of new techniques for the measurement of field velocities in hydraulic problems. The technological advances in digital cameras with high resolution and high speed found in the market, and the advances in digital image processing techniques now provides a tremendous potential to measure and study the behavior of the water surface flows. This technique was applied at the Laboratory of Hydraulics at the Technical University of Catalonia - Barcelona Tech to study the 2D velocity fields in the vicinity of a grate inlet. We used a platform to test grate inlets capacity with dimensions of 5.5 m long and 4 m wide allowing a zone of useful study of 5.5m x 3m, where the width is similar of the urban road lane. The platform allows you to modify the longitudinal slopes from 0% to 10% and transversal slope from 0% to 4%. Flow rates can arrive to 200 l/s. In addition a high resolution camera with 1280 x 1024 pixels resolution with maximum speed of 488 frames per second was used. A novel technique using particle image velocimetry to measure surface flow velocities has been developed and validated with the experimental data from the grate inlets capacity. In this case, the proposed methodology can become a useful tools to understand the velocity fields of the flow approaching the inlet where the traditional measuring equipment have serious problems and limitations. References DigiFlow User Guide. (2012), (June). Russo, B., Gómez, M., & Tellez, J. (2013). Methodology to Estimate the Hydraulic Efficiency of Nontested Continuous Transverse Grates. Journal of Irrigation and Drainage Engineering, 139(10), 864-871. doi:10.1061/(ASCE)IR.1943-4774.0000625 Teresa Vila (1), Jackson Tellez (1), Jesus Maria Sanchez (2), Laura Sotillos (1), Margarita Diez (3, 1), and J., & (1), M. R. (2014). Diffusion in fractal wakes and convective thermoelectric flows. Geophysical Research Abstracts - EGU General Assembly 2014

  2. Flying with the wind: Scale dependency of speed and direction measurements in modelling wind support in avian flight

    Science.gov (United States)

    Safi, Kamran; Kranstauber, Bart; Weinzierl, Rolf P.; Griffin, Larry; Reese, Eileen C.; Cabot, David; Cruz, Sebastian; Proaño, Carolina; Takekawa, John Y.; Newman, Scott H.; Waldenström, Jonas; Bengtsson, Daniel; Kays, Roland; Wikelski, Martin; Bohrer, Gil

    2013-01-01

    Background: Understanding how environmental conditions, especially wind, influence birds' flight speeds is a prerequisite for understanding many important aspects of bird flight, including optimal migration strategies, navigation, and compensation for wind drift. Recent developments in tracking technology and the increased availability of data on large-scale weather patterns have made it possible to use path annotation to link the location of animals to environmental conditions such as wind speed and direction. However, there are various measures available for describing not only wind conditions but also the bird's flight direction and ground speed, and it is unclear which is best for determining the amount of wind support (the length of the wind vector in a bird’s flight direction) and the influence of cross-winds (the length of the wind vector perpendicular to a bird’s direction) throughout a bird's journey.Results: We compared relationships between cross-wind, wind support and bird movements, using path annotation derived from two different global weather reanalysis datasets and three different measures of direction and speed calculation for 288 individuals of nine bird species. Wind was a strong predictor of bird ground speed, explaining 10-66% of the variance, depending on species. Models using data from different weather sources gave qualitatively similar results; however, determining flight direction and speed from successive locations, even at short (15 min intervals), was inferior to using instantaneous GPS-based measures of speed and direction. Use of successive location data significantly underestimated the birds' ground and airspeed, and also resulted in mistaken associations between cross-winds, wind support, and their interactive effects, in relation to the birds' onward flight.Conclusions: Wind has strong effects on bird flight, and combining GPS technology with path annotation of weather variables allows us to quantify these effects for

  3. A multi-time-step noise reduction method for measuring velocity statistics from particle tracking velocimetry

    Science.gov (United States)

    Machicoane, Nathanaël; López-Caballero, Miguel; Bourgoin, Mickael; Aliseda, Alberto; Volk, Romain

    2017-10-01

    We present a method to improve the accuracy of velocity measurements for fluid flow or particles immersed in it, based on a multi-time-step approach that allows for cancellation of noise in the velocity measurements. Improved velocity statistics, a critical element in turbulent flow measurements, can be computed from the combination of the velocity moments computed using standard particle tracking velocimetry (PTV) or particle image velocimetry (PIV) techniques for data sets that have been collected over different values of time intervals between images. This method produces Eulerian velocity fields and Lagrangian velocity statistics with much lower noise levels compared to standard PIV or PTV measurements, without the need of filtering and/or windowing. Particle displacement between two frames is computed for multiple different time-step values between frames in a canonical experiment of homogeneous isotropic turbulence. The second order velocity structure function of the flow is computed with the new method and compared to results from traditional measurement techniques in the literature. Increased accuracy is also demonstrated by comparing the dissipation rate of turbulent kinetic energy measured from this function against previously validated measurements.

  4. Temperature and velocity measurement fields of fluids using a schlieren system.

    Science.gov (United States)

    Martínez-González, Adrian; Guerrero-Viramontes, J A; Moreno-Hernández, David

    2012-06-01

    This paper proposes a combined method for two-dimensional temperature and velocity measurements in liquid and gas flow using a schlieren system. Temperature measurements are made by relating the intensity level of each pixel in a schlieren image to the corresponding knife-edge position measured at the exit focal plane of the schlieren system. The same schlieren images were also used to measure the velocity of the fluid flow. The measurement is made by using particle image velocimetry (PIV). The PIV software used in this work analyzes motion between consecutive schlieren frames to obtain velocity fields. The proposed technique was applied to measure the temperature and velocity fields in the natural convection of water provoked by a heated rectangular plate.

  5. Using Smartphone Pressure Sensors to Measure Vertical Velocities of Elevators, Stairways, and Drones

    Science.gov (United States)

    Monteiro, Martín; Martí, Arturo C.

    2017-01-01

    We measure the vertical velocities of elevators, pedestrians climbing stairs, and drones (flying unmanned aerial vehicles), by means of smartphone pressure sensors. The barometric pressure obtained with the smartphone is related to the altitude of the device via the hydrostatic approximation. From the altitude values, vertical velocities are…

  6. A Fabry-Perot interferometer system for high-speed velocity measurement

    NARCIS (Netherlands)

    Cheng, L.K.; Bruinsma, A.J.A.; Prinse, W.C.; Smorenburg, C.

    1997-01-01

    The Fabry-Perot Velocity Interferometer System (F-PVIS) is designed and built for measuring the Doppler shift of light by recording positional changes in the interferometric pattern behind the Fabry-Perot interferometer. The velocity of a surface can be deduced from the Doppler shift which is caused

  7. Measurement of the burning velocity of propane-air mixtures using soap bubbles

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, Yukio

    1988-12-20

    By filling a soap bubble with propane-air mixture of spacified equivalence ratio and by igniting it at the center, the flame propagation velocity was measured applying multiplex exposure Schlieren method. And the flow velocity of the unburnt propane-air mixture was also measured by a hot-wire anemometer. From the differences of the above two velocities, the burning velocity was obtained. The values of the burning velocity agreed well with the highly accurate results of usual measurements. The maximum value of the burning velocity, which exists at an equivalence ratio of 1.1, was 50cm/s. This value agreed well with the theoretical calculation result on the on-dimensional flame by Warnatz. The burning velocity in the range of from 0.7 to 1.5 equivalence ratios decreases symmetrically with the maximum value at the center. The velocity decrease in the excessive concentration range of fuel is only a little and converges between 7 and 10 cm/s. To evade the influence of the flame-front instability, measurements were done from 2 to 5cm from the ignition center. Thus accurate values were obtained. 23 refs., 5 figs.

  8. In-situ measurements of a highly fragmented comet: WIND STICS Measurements

    Science.gov (United States)

    Lepri, S. T.; Gilbert, J. A.; Gruesbeck, J. R.; Rubin, M.; Gershman, D. J.; Zurbuchen, T.

    2013-12-01

    In this paper, we present in-situ observations of cometary fragments associated with Comet 73P/Schwassmann-Wachmann as it passed very close to the Earth (<0.07AU) in 2006. We examine the spatial distribution of the fragments and the characteristics of the picked up ion velocity distributions. Comet 73P started to disintegrate in 1995, two major components B and C were recovered in 2001, and it burst into more than 36 pieces during its passage near the Earth in 2006. Distant fragmentation members, well-separated from the major identified fragments, passed between the Earth and Sun so that cometary pickup ions and possibly recombined solar wind minor ions convected past the WIND spacecraft in late May 2006. The Suprathermal Ion Composition Spectrometer on WIND provides a rare and detailed 3D glimpse of the newly picked up ion properties.

  9. Horizontal and vertical winds and temperatures in the equatorial thermosphere: measurements from Natal, Brazil during August-September 1982

    International Nuclear Information System (INIS)

    Biondi, M.A.

    1985-01-01

    Fabry-Perot interferometer measurements of Doppler shifts and widths of the 630.0 nm nightglow line have been used to determine the neutral winds and temperatures in the equatorial thermosphere over Natal, Brazil during August-September 1982. During this period, in the early night (2130 U.T.) the average value of the horizontal wind vector was 95 m s -1 at 100 0 azimuth, and the temperature varied from a low of 950 K during geomagnetically quiet conditions to a high of approx. 1400 K during a storm (6 September). The meridional winds were small, -1 , and the eastward zonal winds reached a maximum value 1-3 h after sunset, in qualitative agreement with TGCM predictions. On 26 August, an observed persistent convergence in the horizontal meridional flow was accompanied by a downward vertical velocity and an increase in the thermospheric temperature measured overhead. Oscillations with periods of 40-45 min in both the zonal and vertical wind velocities were observed during the geomagnetic storm of 6 September, suggesting gravity wave modulation of the equatorial thermospheric flow. (author)

  10. Photon trajectories, anomalous velocities and weak measurements: a classical interpretation

    International Nuclear Information System (INIS)

    Bliokh, Konstantin Y; Kofman, Abraham G; Nori, Franco; Bekshaev, Aleksandr Y

    2013-01-01

    Recently, Kocsis et al (2011 Science 332 1170) reported the observation of ‘average trajectories of single photons’ in a two-slit interference experiment. This was possible by using the quantum weak-measurement method, which implies averaging over many events, i.e. in fact, a multi-photon limit of classical linear optics. We give a classical-optics interpretation of this experiment and other related problems. It appears that weak measurements of the local momentum of photons made by Kocsis et al represent measurements of the Poynting vector in an optical field. We consider both the real and imaginary parts of the local momentum and show that their measurements have been realized in classical optics using small-probe particles. We also examine the appearance of ‘anomalous’ values of the local momentum: either negative (backflow) or exceeding the wavenumber (superluminal propagation). These features appear to be closely related to vortices and evanescent waves. Finally, we revisit a number of older works and find examples of photon trajectories and anomalous-momentum measurements in various optical experiments. (paper)

  11. Evaluation of StereoPIV Measurement of Droplet Velocity in an Effervescent Spray

    Directory of Open Access Journals (Sweden)

    Sina Ghaemi

    2010-06-01

    Full Text Available Particle image velocimetry (PIV is a well known technique for measuring the instantaneous velocity field of flows. However, error may be introduced when measuring the velocity field of sprays using this technique when the spray droplets are used as the seed particles. In this study, the effect of droplet number density, droplet velocity profile, and droplet size distribution of a spray produced by an effervescent atomizer on velocity measurement using a StereoPIV has been investigated. A shadowgraph-particle tracking velocimetry (S-PTV system provided measurement of droplet size and velocity for comparison. This investigation demonstrated that the StereoPIV under-estimates velocity at near-field dense spray region where measurement accuracy is limited by multi-scattering of the laser sheet. In the dilute far-field region of the spray, StereoPIV measurement is mostly in agreement with velocity of the droplet size-class which is close to the mean diameter based on droplet number frequency times droplet cross sectional area.

  12. Near-field acoustic holography with sound pressure and particle velocity measurements

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren

    of the particle velocity has notable potential in NAH, and furthermore, combined measurement of sound pressure and particle velocity opens a new range of possibilities that are examined in this study. On this basis, sound field separation methods have been studied, and a new measurement principle based on double...... layer measurements of the particle velocity has been proposed. Also, the relation between near-field and far-field radiation from sound sources has been examined using the concept of the supersonic intensity. The calculation of this quantity has been extended to other holographic methods, and studied...

  13. Velocity Profile measurements in two-phase flow using multi-wave sensors

    Science.gov (United States)

    Biddinika, M. K.; Ito, D.; Takahashi, H.; Kikura, H.; Aritomi, M.

    2009-02-01

    Two-phase flow has been recognized as one of the most important phenomena in fluid dynamics. In addition, gas-liquid two-phase flow appears in various industrial fields such as chemical industries and power generations. In order to clarify the flow structure, some flow parameters have been measured by using many effective measurement techniques. The velocity profile as one of the important flow parameter, has been measured by using ultrasonic velocity profile (UVP) technique. This technique can measure velocity distributions along a measuring line, which is a beam formed by pulse ultrasounds. Furthermore, a multi-wave sensor can measure the velocity profiles of both gas and liquid phase using UVP method. In this study, two types of multi-wave sensors are used. A sensor has cylindrical shape, and another one has square shape. The piezoelectric elements of each sensor have basic frequencies of 8 MHz for liquid phase and 2 MHz for gas phase, separately. The velocity profiles of air-water bubbly flow in a vertical rectangular channel were measured by using these multi-wave sensors, and the validation of the measuring accuracy was performed by the comparison between the velocity profiles measured by two multi-wave sensors.

  14. Velocity Profile measurements in two-phase flow using multi-wave sensors

    International Nuclear Information System (INIS)

    Biddinika, M K; Ito, D; Takahashi, H; Kikura, H; Aritomi, M

    2009-01-01

    Two-phase flow has been recognized as one of the most important phenomena in fluid dynamics. In addition, gas-liquid two-phase flow appears in various industrial fields such as chemical industries and power generations. In order to clarify the flow structure, some flow parameters have been measured by using many effective measurement techniques. The velocity profile as one of the important flow parameter, has been measured by using ultrasonic velocity profile (UVP) technique. This technique can measure velocity distributions along a measuring line, which is a beam formed by pulse ultrasounds. Furthermore, a multi-wave sensor can measure the velocity profiles of both gas and liquid phase using UVP method. In this study, two types of multi-wave sensors are used. A sensor has cylindrical shape, and another one has square shape. The piezoelectric elements of each sensor have basic frequencies of 8 MHz for liquid phase and 2 MHz for gas phase, separately. The velocity profiles of air-water bubbly flow in a vertical rectangular channel were measured by using these multi-wave sensors, and the validation of the measuring accuracy was performed by the comparison between the velocity profiles measured by two multi-wave sensors.

  15. Improved flow velocity estimates from moving-boat ADCP measurements

    NARCIS (Netherlands)

    Vermeulen, B.; Hoitink, A.J.F.; Sassi, M.G.

    2014-01-01

    Acoustic Doppler current profilers (ADCPs) are the current standard for flow measurements in large-scale open water systems. Existing techniques to process vessel-mounted ADCP data assume homogeneous or linearly changing flow between the acoustic beams. This assumption is likely to fail but is

  16. Improved flow velocity estmates from oving-boat ADCO measurements

    NARCIS (Netherlands)

    Vermeulen, B.; Sassi, M.G.; Hoitink, A.J.F.

    2014-01-01

    Acoustic Doppler current profilers (ADCPs) are the current standard for flow measurements in large-scale open water systems. Existing techniques to process vessel-mounted ADCP data assume homogeneous or linearly changing flow between the acoustic beams. This assumption is likely to fail but is

  17. An Estimate of Solar Wind Velocity Profiles in a Coronal Hole and a Coronal Streamer Area (6-40 R(radius symbol)

    Science.gov (United States)

    Patzold, M.; Tsurutani, B. T.; Bird, M. K.

    1995-01-01

    Total electron content data obtained from the Ulysses Solar Corona Experiment (SCE) in 1991 were used to select two data sets, one associated with a coronal hole and the other with coronal streamer crossings. (This is largely equatorial data shortly after solar maximum.) The solar wind velocity profile is estimated for these areas.

  18. Measurement of longitudinal and rayleigh wave velocities by advanced one-sided technique in concrete

    International Nuclear Information System (INIS)

    Lee, Joon Hyun; Song, Won Joon; Popovics, J. S.; Achenbach, J. D.

    1997-01-01

    A new procedure for the advanced one-sided measurement of longitudinal wave and surface wave velocities in concrete is presented in this paper. Stress waves are generated in a consistent fashion with a DC solenoid. Two piezoelectric accelerometers are mounted on the surface of a specimen as receivers. Stress waves propagate along the surface of the specimen and are detected by the receivers. In order to reduce the large incoherent noise levels of the signals, signals are collected and manipulated by a computer program for each velocity measurement. For a known distance between the two receivers and using the measured flight times, the velocities of the longitudinal wave and the surface wave are measured. The velocities of the longitudinal wave determined by this method are compared with those measured by conventional methods on concrete, PMMA and steel.

  19. Field measurement of wind pressure and wind-induced vibration of large-span spatial cable-truss system under strong wind or typhoon

    Directory of Open Access Journals (Sweden)

    ZHANG Zhihong

    2013-10-01

    Full Text Available In order to ensure wind-resistance safety of large-span pre-stressed flexible system in southeast coast area of China,and to prepare something for revising of current codes of practice or technical standards,the present paper conducts field measurement of wind pressure and wind-induced vibration of a practical and typical large-span spatial cable-truss system-lunar stadium in Yueqing city.Wind loading and wind effects on full-scale structure under strong wind or typhoon in real architectural environment can be obtained directly and effectively.Field measurement is the best way to investigate the wind loading property,wind effects,and wind-structure interactions of large-span flexible system.Measured data will be highly valuable for scientific research and practical design.On the other hand,it also provides the basis of wind-resistance safety design of this kind of tension structures.If any creative development,it would dramatically improve the research level of large-span pre-stressed flexible system in our country.

  20. CAT LIDAR wind shear studies

    Science.gov (United States)

    Goff, R. W.

    1978-01-01

    The studies considered the major meteorological factors producing wind shear, methods to define and classify wind shear in terms significant from an aircraft perturbation standpoint, the significance of sensor location and scan geometry on the detection and measurement of wind shear, and the tradeoffs involved in sensor performance such as range/velocity resolution, update frequency and data averaging interval.

  1. Measurement of lithium target surface velocity in the IFMIF/EVEDA lithium test loop

    Energy Technology Data Exchange (ETDEWEB)

    Kanemura, Takuji, E-mail: kanemura.takuji@jaea.go.jp [Japan Atomic Energy Agency, 4002 Narita, O-arai, Higashi-Ibaraki-gun, Ibaraki 311-1393 (Japan); Kondo, Hiroo; Furukawa, Tomohiro; Hirakawa, Yasushi [Japan Atomic Energy Agency, 4002 Narita, O-arai, Higashi-Ibaraki-gun, Ibaraki 311-1393 (Japan); Hoashi, Eiji [Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); Yoshihashi, Sachiko; Horiike, Hiroshi [Fukui University of Technology, Gakuen 3-6-1, Fukui-shi, Fukui 910-8505 (Japan); Wakai, Eiichi [Japan Atomic Energy Agency, 4002 Narita, O-arai, Higashi-Ibaraki-gun, Ibaraki 311-1393 (Japan)

    2016-11-01

    Highlights: • The objective is to measure the free-surface velocity field of the IFMIF Li target. • The Li target has an important role to remove 10 MW heat input from a deuteron beam. • The free-surface of the Li target is under the most severe heat load condition. • Measured surface velocities are almost equal to cross-sectional average velocities. • It was confirmed that the IFMIF Li target has adequate heat removal performance. - Abstract: In the framework of the Engineering Validation and Engineering Design Activities (EVEDA) project of the International Fusion Materials Irradiation Facility (IFMIF), we measured surface velocity fields of a lithium (Li) target at the EVEDA Li test loop under specifically-designated IFMIF conditions (target speeds of 10, 15, and 20 m/s, vacuum pressure of 10{sup −3} Pa, and Li temperature of 250 °C). In the current design of the IFMIF, the free surface of the Li target is under a most severe heat load condition with respect to Li boiling. The objective of this study is to measure the actual free-surface velocity under these IFMIF conditions to evaluate the heat removal performance of the Li target. The measured results (using the surface-wave tracking method that our team developed) showed two-dimensional time-averaged velocity distributions around the IFMIF beam footprint being virtually uniform, and close to the cross-sectional average velocity. The uniformity of the velocity distributions was less than 1 m/s. The comparison between the measured and analyzed surface velocity at the beam center showed that the analysis accurately predicts the measurement results within a margin of 3%. Finally, it was confirmed that the Li target delivers adequate heat removal performance in the IFMIF as designed.

  2. New Interpretations of Measured Antihydrogen Velocities and Field Ionization Spectra

    International Nuclear Information System (INIS)

    Pohl, T.; Sadeghpour, H. R.; Gabrielse, G.

    2006-01-01

    We present extensive Monte Carlo simulations, showing that cold antihydrogen (H) atoms are produced when antiprotons (p) are gently heated in the side wells of a nested Penning trap. The observed H with high energies, that had seemed to indicate otherwise, are instead explained by a surprisingly effective charge-exchange mechanism. We shed light on the previously measured field-ionization spectrum, and reproduce both the characteristic low-field power law as well as the enhanced H production at higher fields. The latter feature is shown to arise from H atoms too deeply bound to be described as guiding center atoms, atoms with internally chaotic motion

  3. Customized DSP-based vibration measurement for wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    LaWhite, N.E.; Cohn, K.E. [Second Wind Inc., Somerville, MA (United States)

    1996-12-31

    As part of its Advanced Distributed Monitoring System (ADMS) project funded by NREL, Second Wind Inc. is developing a new vibration measurement system for use with wind turbines. The system uses low-cost accelerometers originally designed for automobile airbag crash-detection coupled with new software executed on a Digital Signal Processor (DSP) device. The system is envisioned as a means to monitor the mechanical {open_quotes}health{close_quotes} of the wind turbine over its lifetime. In addition the system holds promise as a customized emergency vibration detector. The two goals are very different and it is expected that different software programs will be executed for each function. While a fast Fourier transform (FFT) signature under given operating conditions can yield much information regarding turbine condition, the sampling period and processing requirements make it inappropriate for emergency condition monitoring. This paper briefly reviews the development of prototype DSP and accelerometer hardware. More importantly, it reviews our work to design prototype vibration alarm filters. Two-axis accelerometer test data from the experimental FloWind vertical axis wind turbine is analyzed and used as a development guide. Two levels of signal processing are considered. The first uses narrow band pre-processing filters at key fundamental frequencies such as the 1P, 2P and 3P. The total vibration energy in each frequency band is calculated and evaluated as a possible alarm trigger. In the second level of signal processing, the total vibration energy in each frequency band is further decomposed using the two-axis directional information. Directional statistics are calculated to differentiate between linear translations and circular translations. After analyzing the acceleration statistics for normal and unusual operating conditions, the acceleration processing system described could be used in automatic early detection of fault conditions. 9 figs.

  4. Magnetic particle imaging for in vivo blood flow velocity measurements in mice

    Science.gov (United States)

    Kaul, Michael G.; Salamon, Johannes; Knopp, Tobias; Ittrich, Harald; Adam, Gerhard; Weller, Horst; Jung, Caroline

    2018-03-01

    Magnetic particle imaging (MPI) is a new imaging technology. It is a potential candidate to be used for angiographic purposes, to study perfusion and cell migration. The aim of this work was to measure velocities of the flowing blood in the inferior vena cava of mice, using MPI, and to evaluate it in comparison with magnetic resonance imaging (MRI). A phantom mimicking the flow within the inferior vena cava with velocities of up to 21 cm s‑1 was used for the evaluation of the applied analysis techniques. Time–density and distance–density analyses for bolus tracking were performed to calculate flow velocities. These findings were compared with the calibrated velocities set by a flow pump, and it can be concluded that velocities of up to 21 cm s‑1 can be measured by MPI. A time–density analysis using an arrival time estimation algorithm showed the best agreement with the preset velocities. In vivo measurements were performed in healthy FVB mice (n  =  10). MRI experiments were performed using phase contrast (PC) for velocity mapping. For MPI measurements, a standardized injection of a superparamagnetic iron oxide tracer was applied. In vivo MPI data were evaluated by a time–density analysis and compared to PC MRI. A Bland–Altman analysis revealed good agreement between the in vivo velocities acquired by MRI of 4.0  ±  1.5 cm s‑1 and those measured by MPI of 4.8  ±  1.1 cm s‑1. Magnetic particle imaging is a new tool with which to measure and quantify flow velocities. It is fast, radiation-free, and produces 3D images. It therefore offers the potential for vascular imaging.

  5. High-resolution humidity profiles retrieved from wind profiler radar measurements

    Science.gov (United States)

    Saïd, Frédérique; Campistron, Bernard; Di Girolamo, Paolo

    2018-03-01

    The retrieval of humidity profiles from wind profiler radars has already been documented in the past 30 years and is known to be neither as straightforward and nor as robust as the retrieval of the wind velocity. The main constraint to retrieve the humidity profile is the necessity to combine measurements from the wind profiler and additional measurements (such as observations from radiosoundings at a coarser time resolution). Furthermore, the method relies on some assumptions and simplifications that restrict the scope of its application. The first objective of this paper is to identify the obstacles and limitations and solve them, or at least define the field of applicability. To improve the method, we propose using the radar capacity to detect transition levels, such as the top level of the boundary layer, marked by a maximum in the radar reflectivity. This forces the humidity profile from the free troposphere and from the boundary layer to coincide at this level, after an optimization of the calibration coefficients, and reduces the error. The resulting mean bias affecting the specific humidity profile never exceeds 0.25 g kg-1. The second objective is to explore the capability of the algorithm to retrieve the humidity vertical profiles for an operational purpose by comparing the results with observations from a Raman lidar.

  6. Measurement of sound velocity on metal surfaces by impulsive stimulated Brillouin scattering

    International Nuclear Information System (INIS)

    Shimada, Yukihiro; Murakami, Hiroshi; Nishimura, Akihiko

    2005-01-01

    Impulsive stimulated Brillouin Scattering (ISBS) experiment was performed in order to measure acoustic waves on metal surfaces. The ISBS technique offers robust method of obtaining acoustic velocities without physical contact. The generation and detection mechanism were discussed. (author)

  7. Theoretical analysis of stack gas emission velocity measurement by optical scintillation

    International Nuclear Information System (INIS)

    Yang Yang; Dong Feng-Zhong; Ni Zhi-Bo; Pang Tao; Zeng Zong-Yong; Wu Bian; Zhang Zhi-Rong

    2014-01-01

    Theoretical analysis for an online measurement of the stack gas flow velocity based on the optical scintillation method with a structure of two parallel optical paths is performed. The causes of optical scintillation in a stack are first introduced. Then, the principle of flow velocity measurement and its mathematical expression based on cross correlation of the optical scintillation are presented. The field test results show that the flow velocity measured by the proposed technique in this article is consistent with the value tested by the Pitot tube. It verifies the effectiveness of this method. Finally, by use of the structure function of logarithmic light intensity fluctuations, the theoretical explanation of optical scintillation spectral characteristic in low frequency is given. The analysis of the optical scintillation spectrum provides the basis for the measurement of the stack gas flow velocity and particle concentration simultaneously. (general)

  8. Measurement of fast-changing low velocities by photonic Doppler velocimetry

    Energy Technology Data Exchange (ETDEWEB)

    Song Hongwei; Wu Xianqian; Huang Chenguang; Wei Yangpeng; Wang Xi [Key Laboratory for Hydrodynamics and Ocean Engineering, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China)

    2012-07-15

    Despite the increasing popularity of photonic Doppler velocimetry (PDV) in shock wave experiments, its capability of capturing low particle velocities while changing rapidly is still questionable. The paper discusses the performance of short time Fourier transform (STFT) and continuous wavelet transform (CWT) in processing fringe signals of fast-changing low velocities measured by PDV. Two typical experiments are carried out to evaluate the performance. In the laser shock peening test, the CWT gives a better interpretation to the free surface velocity history, where the elastic precursor, main plastic wave, and elastic release wave can be clearly identified. The velocities of stress waves, Hugoniot elastic limit, and the amplitude of shock pressure induced by laser can be obtained from the measurement. In the Kolsky-bar based tests, both methods show validity of processing the longitudinal velocity signal of incident bar, whereas CWT improperly interprets the radial velocity of the shocked sample at the beginning period, indicating the sensitiveness of the CWT to the background noise. STFT is relatively robust in extracting waveforms of low signal-to-noise ratio. Data processing method greatly affects the temporal resolution and velocity resolution of a given fringe signal, usually CWT demonstrates a better local temporal resolution and velocity resolution, due to its adaptability to the local frequency, also due to the finer time-frequency product according to the uncertainty principle.

  9. Recent results from the ICARUS experiment - Measurements concerning neutrino velocity

    International Nuclear Information System (INIS)

    Cieslik, K.

    2014-01-01

    The ICARUS T600 detector at the LNGS Gran Sasso underground Laboratory is the first large mass Liquid Argon Time Projection Chamber (LAr-TPC) designed to study the ν μ → ν τ oscillation for neutrinos from the CERN-CNGS beam, the atmospheric neutrinos and matter stability. In stable conditions the detector has been collecting data since October 2010. The results, presented here, of the search for analogue to the Cherenkov radiation at superluminal speeds and the measurement of the neutrino time of flight are incompatible with the OPERA collaboration claiming that CNGS muon neutrinos arrive to Gran Sasso, after covering a distance of about 732 km, earlier than expected from the luminal speed. (author)

  10. Group velocity measurement using spectral interference in near-field scanning optical microscopy

    International Nuclear Information System (INIS)

    Mills, John D.; Chaipiboonwong, Tipsuda; Brocklesby, William S.; Charlton, Martin D. B.; Netti, Caterina; Zoorob, Majd E.; Baumberg, Jeremy J.

    2006-01-01

    Near-field scanning optical microscopy provides a tool for studying the behavior of optical fields inside waveguides. In this experiment the authors measure directly the variation of group velocity between different modes of a planar slab waveguide as the modes propagate along the guide. The measurement is made using the spectral interference between pulses propagating inside the waveguide with different group velocities, collected using a near-field scanning optical microscope at different points down the guide and spectrally resolved. The results are compared to models of group velocities in simple guides

  11. Modelling and Measuring Flow and Wind Turbine Wakes in Large Wind Farms Offshore

    DEFF Research Database (Denmark)

    Barthelmie, Rebecca Jane; Hansen, Kurt Schaldemose; Frandsen, Sten Tronæs

    2009-01-01

    power losses due to wakes and loads. The research presented is part of the EC-funded UpWind project, which aims to radically improve wind turbine and wind farm models in order to continue to improve the costs of wind energy. Reducing wake losses, or even reduce uncertainties in predicting power losses...

  12. Neutral wind measurements by Fabry-Perot interferometry in Antarctica

    International Nuclear Information System (INIS)

    Stewart, K.D.; Dudeney, J.R.; Rodger, A.S.; Smith, R.W.; Rees, D.

    1986-01-01

    A large-aperture (150 mm), spatially scanned Fabry-Perot Interferometer (FPI) has been deployed at Halley (75.5 o S, 26.8 o W; L=4.2), Antarctica. Thermospheric neutral wind measurements were made by finding the Doppler shift of the OI( 3 P 2 - 1 D 2 ) 630.0 nm emission. This has allowed the first comparison to be made between southern hemisphere ground-based thermospheric wind measurements and the predictions of a three-dimensional, time-dependent thermospheric global circulation model. Geomagnetic and geographic latitude are well separated at Halley, so we may expect a distinct contrast to the dynamic behaviour observed in the more frequently studied northern polar thermosphere. Although the initial results from the experiment are in general agreement with the model, some consistent and significant differences between the observed wind field and that predicted are evident in the morning sector. These may be related to uncertainties in mapping magnetospheric boundaries to ionospheric heights in the southern hemisphere. The intensity of the 630 nm emission has been examined with respect to the maximum plasma frequency of the Es layer using data from the Advanced Ionospheric Sounder at Halley

  13. Measurement of two-dimensional bubble velocity by Using tri-fiber-optical Probe

    International Nuclear Information System (INIS)

    Yang Ruichang; Zheng Rongchuan; Zhou Fanling; Liu Ruolei

    2009-01-01

    In this study, an advanced measuring system with a tri-single-fiber-optical-probe has been developed to measure two-dimensional vapor/gas bubble velocity. The use of beam splitting devices instead of beam splitting lens simplifies the optical system, so the system becomes more compact and economic, and more easy to adjust. Corresponding to using triple-optical probe for measuring two-dimensional bubble velocity, a data processing method has been developed, including processing of bubble signals, cancelling of unrelated signals, determining of bubble velocity with cross correlation technique and so on. Using the developed two-dimensional bubble velocity measuring method, the rising velocity of air bubbles in gravitational field was measured. The measured bubble velocities were compared with the empirical correlation available. Deviation was in the range of ±30%. The bubble diameter obtained by data processing is in good accordance with that observed with a synchro-scope and a camera. This shows that the method developed here is reliable.

  14. Energy Demodulation Algorithm for Flow Velocity Measurement of Oil-Gas-Water Three-Phase Flow

    Directory of Open Access Journals (Sweden)

    Yingwei Li

    2014-01-01

    Full Text Available Flow velocity measurement was an important research of oil-gas-water three-phase flow parameter measurements. In order to satisfy the increasing demands for flow detection technology, the paper presented a gas-liquid phase flow velocity measurement method which was based on energy demodulation algorithm combing with time delay estimation technology. First, a gas-liquid phase separation method of oil-gas-water three-phase flow based on energy demodulation algorithm and blind signal separation technology was proposed. The separation of oil-gas-water three-phase signals which were sampled by conductance sensor performed well, so the gas-phase signal and the liquid-phase signal were obtained. Second, we used the time delay estimation technology to get the delay time of gas-phase signals and liquid-phase signals, respectively, and the gas-phase velocity and the liquid-phase velocity were derived. At last, the experiment was performed at oil-gas-water three-phase flow loop, and the results indicated that the measurement errors met the need of velocity measurement. So it provided a feasible method for gas-liquid phase velocity measurement of the oil-gas-water three-phase flow.

  15. Diode Laser Velocity Measurements by Modulated Filtered Rayleigh Scattering

    Science.gov (United States)

    Mach, J. J.; Varghese, P. L.; Jagodzinski, J. J.

    1999-01-01

    The ability of solid-state lasers to be tuned in operating frequency at MHz rates by input current modulation, while maintaining a relatively narrow line-width, has made them useful for spectroscopic measurements. Their other advantages include low cost, reliability, durability, compact size, and modest power requirements, making them a good choice for a laser source in micro-gravity experiments in drop-towers and in flight. For their size, they are also very bright. In a filtered Rayleigh scattering (FRS) experiment, a diode laser can be used to scan across an atomic or molecular absorption line, generating large changes in transmission at the resonances for very small changes in frequency. The hyperfine structure components of atomic lines of alkali metal vapors are closely spaced and very strong, which makes such atomic filters excellent candidates for sensitive Doppler shift detection and therefore for high-resolution velocimetry. In the work we describe here we use a Rubidium vapor filter, and work with the strong D(sub 2) transitions at 780 nm that are conveniently accessed by near infrared diode lasers. The low power output of infrared laser diodes is their primary drawback relative to other laser systems commonly used for velocimetry. However, the capability to modulate the laser frequency rapidly and continuously helps mitigate this. Using modulation spectroscopy and a heterodyne detection scheme with a lock-in amplifier, one can extract sub-microvolt signals occurring at a specific frequency from a background that is orders of magnitude stronger. The diode laser modulation is simply achieved by adding a small current modulation to the laser bias current. It may also be swept repetitively in wavelength using an additional lower frequency current ramp.

  16. Diode laser lidar wind velocity sensor using a liquid-crystal retarder for non-mechanical beam-steering

    DEFF Research Database (Denmark)

    Rodrigo, Peter John; Iversen, Theis Faber Quist; Hu, Qi

    2014-01-01

    it either transmits throughor reflects off a polarization splitter. The room-temperature switching timebetween the two LOS is measured to be in the order of 100μs in one switchdirection but 16 ms in the opposite transition. Radial wind speedmeasurement (at 33 Hz rate) while the lidar beam is repeatedly...... the lidar probe beam in two different lines-of-sight (LOS) with a 60° angular separation. Dual-LOS beam-steering isimplemented optically with no moving parts by means of a controllableliquid-crystal retarder (LCR). The LCR switches the polarization betweentwo orthogonal linear states of the lidar beam so...

  17. Front-Crawl Instantaneous Velocity Estimation Using a Wearable Inertial Measurement Unit

    Directory of Open Access Journals (Sweden)

    Kamiar Aminian

    2012-09-01

    Full Text Available Monitoring the performance is a crucial task for elite sports during both training and competition. Velocity is the key parameter of performance in swimming, but swimming performance evaluation remains immature due to the complexities of measurements in water. The purpose of this study is to use a single inertial measurement unit (IMU to estimate front crawl velocity. Thirty swimmers, equipped with an IMU on the sacrum, each performed four different velocity trials of 25 m in ascending order. A tethered speedometer was used as the velocity measurement reference. Deployment of biomechanical constraints of front crawl locomotion and change detection framework on acceleration signal paved the way for a drift-free integration of forward acceleration using IMU to estimate the swimmers velocity. A difference of 0.6 ± 5.4 cm·s−1 on mean cycle velocity and an RMS difference of 11.3 cm·s−1 in instantaneous velocity estimation were observed between IMU and the reference. The most important contribution of the study is a new practical tool for objective evaluation of swimming performance. A single body-worn IMU provides timely feedback for coaches and sport scientists without any complicated setup or restraining the swimmer’s natural technique.

  18. Isolated systems with wind power. Results of measurements in Egypt

    DEFF Research Database (Denmark)

    Bindner, Henrik W.; Saleh, L.; Hafiez, S.A.

    2001-01-01

    different sites. Three of the sites were in Hurghada, where the power system is rather large. The last two measurement sites were at village systems: one large system and one with only power ca. five hours perday. The measured load profiles were quite different at the different sites. The power quality...... at the different sites was adequate even at the small village sites where the load is almost constant. The impact of different load profiles on the technicaland economic performance of a wind diesel system in the feasibility phase was investigated. The results indicate that when the profile has low values...

  19. Hybrid method for determining the parameters of condenser microphones from measured membrane velocities and numerical calculations

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Rasmussen, Knud; Jacobsen, Finn

    2009-01-01

    to this problem is to measure the velocity distribution of the membrane by means of a non-contact method, such as laser vibrometry. The measured velocity distribution can be used together with a numerical formulation such as the boundary element method for estimating the microphone response and other parameters......, e.g., the acoustic center. In this work, such a hybrid method is presented and examined. The velocity distributions of a number of condenser microphones have been determined using a laser vibrometer, and these measured velocity distributions have been used for estimating microphone responses......Typically, numerical calculations of the pressure, free-field, and random-incidence response of a condenser microphone are carried out on the basis of an assumed displacement distribution of the diaphragm of the microphone; the conventional assumption is that the displacement follows a Bessel...

  20. Investigation of the Impact of the Upstream Induction Zone on LIDAR Measurement Accuracy for Wind Turbine Control Applications using Large-Eddy Simulation

    International Nuclear Information System (INIS)

    Simley, Eric; Pao, Lucy Y; Gebraad, Pieter; Churchfield, Matthew

    2014-01-01

    Several sources of error exist in lidar measurements for feedforward control of wind turbines including the ability to detect only radial velocities, spatial averaging, and wind evolution. This paper investigates another potential source of error: the upstream induction zone. The induction zone can directly affect lidar measurements and presents an opportunity for further decorrelation between upstream wind and the wind that interacts with the rotor. The impact of the induction zone is investigated using the combined CFD and aeroelastic code SOWFA. Lidar measurements are simulated upstream of a 5 MW turbine rotor and the true wind disturbances are found using a wind speed estimator and turbine outputs. Lidar performance in the absence of an induction zone is determined by simulating lidar measurements and the turbine response using the aeroelastic code FAST with wind inputs taken far upstream of the original turbine location in the SOWFA wind field. Results indicate that while measurement quality strongly depends on the amount of wind evolution, the induction zone has little effect. However, the optimal lidar preview distance and circular scan radius change slightly due to the presence of the induction zone

  1. Comparison of shear-wave velocity measurements by crosshole, downhole and seismic cone penetration test methods

    Energy Technology Data Exchange (ETDEWEB)

    Suthaker, N.; Tweedie, R. [Thurber Engineering Ltd., Edmonton, AB (Canada)

    2009-07-01

    Shear wave velocity measurements are an integral part of geotechnical studies for major structures and are an important tool in their design for site specific conditions such as site-specific earthquake response. This paper reported on a study in which shear wave velocities were measured at a proposed petrochemical plant site near Edmonton, Alberta. The proposed site is underlain by lacustrine clay, glacial till and upper Cretaceous clay shale and sandstone bedrock. The most commonly used methods for determining shear wave velocity include crosshole seismic tests, downhole seismic tests, and seismic cone penetration tests (SCPT). This paper presented the results of all 3 methods used in this study and provided a comparison of the various test methods and their limitations. The crosshole test results demonstrated a common trend of increasing shear wave velocity with depth to about 15 m, below which the velocities remained relatively constant. An anomaly was noted at one site, where the shear wave velocity was reduced at a zone corresponding to clay till containing stiff high plastic clay layers. The field study demonstrated that reasonable agreement in shear wave velocity measurements can be made using crosshole, downhole and seismic tests in the same soil conditions. The National Building Code states that the shear wave velocity is the fundamental method for determining site classification, thus emphasizing the importance of obtaining shear wave velocity measurements for site classification. It was concluded that an SCPT program can be incorporated into the field program without much increase in cost and can be supplemented by downhole or crosshole techniques. 5 refs., 2 tabs., 10 figs.

  2. Acoustic Emission Stethoscope - Measurements with Acoustic Emission on Wind Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Krystof Kryniski [AaF Infrastructure, Stockholm (Sweden)

    2013-02-15

    A remote ultrasonic stethoscope, designed on mobile devices to help a maintenance team in diagnosing drive train problems, has been demonstrated. By implementing an acoustic emission technology, the operating conditions of wind turbines have been assessed by trending techniques and ultrasonic acoustic emission converted into audible sound. The new approach has been developed and tested and compared to other monitoring techniques. Acoustic emission has generally been shown to provide a number of advantages over vibration and shock pulse methods because the system is operating in a substantially higher frequency range (100 kHz) and therefore it is more immune to operation of surrounding machines and components. Quick attenuation of ultrasonic propagation waves in the drive-train structure helps to pin-point the origin of any fault as the signals are sharper and more pronounced. Further, with the intensity measurements a direction of the source of ultrasonic energy can be identified. Using a high frequency thus makes the method suitable for measuring local effects and to determine local defects since the disturbing signals from other parts are damped. Recently developed programmable sensors capable of processing signals onboard, producing quality outputs with extremely low noise-to-signal ratio, have been used. It is discussed how the new approach can lower the cost of a wind-turbine monitoring system, while at the same time making it simple and more reliable, see Appendix A. The method has been tested on rotating parts of wind-turbines, including traditionally difficult areas such as low speed main bearings and planetary gearboxes. The method developed in the project was designed to see physical processes such as friction, impacts and metal removal, occurring when machinery degrades, can be detected and notified with the developed notification system. Apart from reporting the status and displaying the changes of the pre-defined parameters or symptoms, the system has

  3. Vibration analysis of 1 MW gearbox for the Avedoere wind turbine. Test bed measurements

    International Nuclear Information System (INIS)

    Crone, A.

    1995-03-01

    The investigations had several purposes: Firstly, to determine and evaluate the structure-borne noise source strength of the gearbox, which is relevant for the final gear noise emission from the wind turbine. Secondly, to select the potentially least noisy gear set out of two, which have been made for the output gear stage. And Thirdly, to obtain the natural vibration modes of the gearbox structure, in order to determine if the structure-borne noise, transmitted to the wind turbine structure, will be amplified due to resonance conditions. Additional vibration tests were carried out. Among these, trials of 'in situ' measurement of the Transmission Error of the output gear stage, and measurements of the torsional vibrations of the input and output shaft. The test of the two output gear sets (from Flender AG and ELKRAFT A.m.b.A.) had the aim to determine the least noisy one of two different tooth profiles. Both gear sets were intended for the Avedoere Wind Turbine when it, in its first period of operation, is going to operate as a stall regulated turbine. After the first mesurements and the exchange of the Flender-designed gear set with the ELKRAFT-designed gear set, troubles with the backmost bearing of the intermediate shaft arose. The evaluation of the structure-borne noise source strength (expressed as the vibration velocity level), has in general been made at load conditions which correspond to the conditions in the wind turibne at a wind speed of 8 m/s, 10 m above terrain (v 10 ). This condition, is the one normally used when the noise emission from wind turbines is evaluated. At the comparison of the two gear sets against each other, the influence of the torque load on the source strength has also been considered. This comparison may indicate the load at which the profile correction is most effective, and may determine the noise potential of the gearbox at wind speeds lower than 8 m/s, which could also be of interest

  4. Implication of Broadband Dispersion Measurements in Constraining Upper Mantle Velocity Structures

    Science.gov (United States)

    Kuponiyi, A.; Kao, H.; Cassidy, J. F.; Darbyshire, F. A.; Dosso, S. E.; Gosselin, J. M.; Spence, G.

    2017-12-01

    Dispersion measurements from earthquake (EQ) data are traditionally inverted to obtain 1-D shear-wave velocity models, which provide information on deep earth structures. However, in many cases, EQ-derived dispersion measurements lack short-period information, which theoretically should provide details of shallow structures. We show that in at least some cases short-period information, such as can be obtained from ambient seismic noise (ASN) processing, must be combined with EQ dispersion measurements to properly constrain deeper (e.g. upper-mantle) structures. To verify this, synthetic dispersion data are generated using hypothetical velocity models under four scenarios: EQ only (with and without deep low-velocity layers) and combined EQ and ASN data (with and without deep low-velocity layers). The now "broadband" dispersion data are inverted using a trans-dimensional Bayesian framework with the aim of recovering the initial velocity models and assessing uncertainties. Our results show that the deep low-velocity layer could only be recovered from the inversion of the combined ASN-EQ dispersion measurements. Given this result, we proceed to describe a method for obtaining reliable broadband dispersion measurements from both ASN and EQ and show examples for real data. The implication of this study in the characterization of lithospheric and upper mantle structures, such as the Lithosphere-Asthenosphere Boundary (LAB), is also discussed.

  5. Turbulence intensity measurement in the wind tunnel used for airfoil flutter investigation

    Directory of Open Access Journals (Sweden)

    Šidlof Petr

    2017-01-01

    Full Text Available The paper reports on hot wire turbulence intensity measurements performed in the entry of a suction-type wind tunnel, used for investigation of flow-induced vibration of airfoils and slender structures. The airfoil is elastically supported with two degrees of freedom (pitch and plunge in the test section of the wind tunnel with lateral optical access for interferometric measurements, and free to oscillate. The turbulence intensity was measured for velocities up to M = 0.3 i with the airfoil blocked, ii with the airfoil self-oscillating. Measurements were performed for a free inlet and further with two different turbulence grids generating increased turbulence intensity levels. For the free inlet and static airfoil, the turbulence intensity lies below 0.4%. The turbulence grids G1 and G2 increase the turbulence level up to 1.8% and 2.6%, respectively. When the airfoil is free to oscillate due to fluid-structure interaction, its motion disturbs the surrounding flow field and increases the measured turbulence intensity levels up to 5%.

  6. Wind Gust Measurement Techniques—From Traditional Anemometry to New Possibilities

    Directory of Open Access Journals (Sweden)

    Irene Suomi

    2018-04-01

    Full Text Available Information on wind gusts is needed for assessment of wind-induced damage and risks to safety. The measurement of wind gust speed requires a high temporal resolution of the anemometer system, because the gust is defined as a short-duration (seconds maximum of the fluctuating wind speed. Until the digitalization of wind measurements in the 1990s, the wind gust measurements suffered from limited recording and data processing resources. Therefore, the majority of continuous wind gust records date back at most only by 30 years. Although the response characteristics of anemometer systems are good enough today, the traditional measurement techniques at weather stations based on cup and sonic anemometers are limited to heights and regions where the supporting structures can reach. Therefore, existing measurements are mainly concentrated over densely-populated land areas, whereas from remote locations, such as the marine Arctic, wind gust information is available only from sparse coastal locations. Recent developments of wind gust measurement techniques based on turbulence measurements from research aircraft and from Doppler lidar can potentially provide new information from heights and locations unreachable by traditional measurement techniques. Moreover, fast-developing measurement methods based on Unmanned Aircraft Systems (UASs may add to better coverage of wind gust measurements in the future. In this paper, we provide an overview of the history and the current status of anemometry from the perspective of wind gusts. Furthermore, a discussion on the potential future directions of wind gust measurement techniques is provided.

  7. Analysis of Wind Energy Potential and Vibrations Caused by Wind Turbine on Its Basement

    Czech Academy of Sciences Publication Activity Database

    Kaláb, Z.; Hanslian, David; Stolárik, M.; Pinka, M.

    2014-01-01

    Roč. 19, č. 3 (2014), s. 151-159 ISSN 1335-1788 Institutional support: RVO:68378289 Keywords : wind turbine * wind energy potential * wind map * wind map * experimental measurement * vibration velocity Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 0.329, year: 2014 http://actamont.tuke.sk/pdf/2014/n3/6kalab.pdf

  8. Total uncertainty of low velocity thermal anemometers for measurement of indoor air movements

    DEFF Research Database (Denmark)

    Jørgensen, F.; Popiolek, Z.; Melikov, Arsen Krikor

    2004-01-01

    For a specific thermal anemometer with omnidirectional velocity sensor the expanded total uncertainty in measured mean velocity Û(Vmean) and the expanded total uncertainty in measured turbulence intensity Û(Tu) due to different error sources are estimated. The values are based on a previously...... developed mathematical model of the anemometer in combination with a large database of representative room flows measured with a 3-D Laser Doppler anemometer (LDA). A direct comparison between measurements with a thermal anemometer and a 3-D LDA in flows of varying velocity and turbulence intensity shows...... good agreement not only between the two instruments but also between the thermal anemometer and its mathematical model. The differences in the measurements performed with the two instruments are all well within the measurement uncertainty of both anemometers....

  9. The Measurement of cloud velocity using the pulsed laser and image tracking technique

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Seong-Ouk; Baik, Seung-Hoon; Park, Seung-Kyu; Park, Nak-Gyu; Kim, Dong-lyul; Ahn, Yong-Jin [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    The height of the clouds is also important for the three dimensional radiative interaction of aerosols and clouds, since the radiative effects vary strongly depending whether the cloud is above, below or even embedded in an aerosol layer. Clouds play an important role in climate change, in the prediction of local weather, and also in aviation safety when instrument assisted flying is unavailable. Presently, various ground-based instruments used for the measurements of the cloud base height or velocity. Lidar techniques are powerful and have many applications in climate studies, including the clouds' temperature measurement, the aerosol particle properties, etc. Otherwise, it is very circumscribed in cloud velocity measurements In this paper, we propose a new method to measure the cloud velocity. In this paper, we presented a method for the measurement of the cloud altitude and velocity using lidar's range detection and the tracking system. For the lidar system, we used an injection-seeded pulsed Nd:YAG laser as the transmitter to measure the distance to the target clouds. We used the DIC system to track the cloud image and calculate the actual displacement per unit time. The configured lidar system acquired the lidar signal of clouds at a distance of about 4 km. The developed fast correlation algorithm of the tracking, which is used to track the fast moving cloud relatively, was efficient for measuring the cloud velocity in real time. The measurement values had a linear distribution.

  10. Utgrunden off-shore wind farm - Measurements of underwater noise

    International Nuclear Information System (INIS)

    Lindell, Hans

    2003-07-01

    Airicole, GE Wind Energy and SEAS/Energi E2 have initiated this project in order to achieve a better understanding on how offshore based wind farms effect the underwater noise. The main reason is to gain knowledge on how marine wildlife could be effected by this kind of installation. The measurements were performed at Utgrunden wind farm that is situated at the reef Utgrunden on the Swedish southeast coast. The farm consists of seven 1,5 MW turbines. Three hydrophones registered the underwater sound and four accelerometers the tower vibrations. The measurement campaign was conducted during a period from November 2002 to February 2003. The objectives with this project is to answer the following issues and its results are: 1. What is the character of sound from a single power station? - The turbines radiate sound mainly at a few dominating frequencies from 30 Hz up to 800 Hz. At frequencies below 3 Hz no contribution from the turbines can be detected due to the high background level from the waves and the low tower vibration level. 2. What are the sound generating mechanisms in the turbine? - Gearbox mesh frequency vibrations that are transmitted via the tower structure and radiated out to the water mainly generate the sound. Airborne blade sound is effectively dampened in the transition from air to water. 3. How does the sound attenuate with increasing distance at different frequencies? - The average attenuation per doubled distance for frequencies between 31 Hz and 722 Hz is approximately 4 dB in the measured positions. No clear frequency dependence could be found. 4. How does the sound pressure level vary with increasing wind speed? - With increasing wind speed, the sound pressure level increases and the dominating frequencies move upward due to increasing turbine rotational speed. 5. How does sound from different power stations interfere with each other and influence the over all sound image? - No clear tendencies of interference could be observed in this study

  11. A dual-phantom system for validation of velocity measurements in stenosis models under steady flow.

    Science.gov (United States)

    Blake, James R; Easson, William J; Hoskins, Peter R

    2009-09-01

    A dual-phantom system is developed for validation of velocity measurements in stenosis models. Pairs of phantoms with identical geometry and flow conditions are manufactured, one for ultrasound and one for particle image velocimetry (PIV). The PIV model is made from silicone rubber, and a new PIV fluid is made that matches the refractive index of 1.41 of silicone. Dynamic scaling was performed to correct for the increased viscosity of the PIV fluid compared with that of the ultrasound blood mimic. The degree of stenosis in the models pairs agreed to less than 1%. The velocities in the laminar flow region up to the peak velocity location agreed to within 15%, and the difference could be explained by errors in ultrasound velocity estimation. At low flow rates and in mild stenoses, good agreement was observed in the distal flow fields, excepting the maximum velocities. At high flow rates, there was considerable difference in velocities in the poststenosis flow field (maximum centreline differences of 30%), which would seem to represent real differences in hydrodynamic behavior between the two models. Sources of error included: variation of viscosity because of temperature (random error, which could account for differences of up to 7%); ultrasound velocity estimation errors (systematic errors); and geometry effects in each model, particularly because of imperfect connectors and corners (systematic errors, potentially affecting the inlet length and flow stability). The current system is best placed to investigate measurement errors in the laminar flow region rather than the poststenosis turbulent flow region.

  12. Dynamic lift measurements on a FX79W151A airfoil via pressure distribution on the wind tunnel walls

    Energy Technology Data Exchange (ETDEWEB)

    Wolken-Moehlmann, Gerrit [ForWind - Center for Wind Energy Research, University of Oldenburg (Germany); Knebel, Pascal [ForWind - Center for Wind Energy Research, University of Oldenburg (Germany); Barth, Stephan [ECN Wind Energy, Energy research Centre of the (Netherlands); Peinke, Joachim [ForWind - Center for Wind Energy Research, University of Oldenburg (Germany)

    2007-07-15

    We report on an experimental setup for measurements of dynamic stall for airfoils via the pressure distribution over wind tunnel walls. This measuring technique, hitherto used for lift measurements under static conditions, is also an adequate method for dynamic conditions until stall occurs. A step motor is used, allowing for sinusoidal as well as non-sinusoidal and stochastic pitching to simulate fast fluctuating flow conditions. Measurements with sinusoidal pitching and constant angular velocities were done and show dynamic stall characteristics. Under dynamic stall conditions, maximum lift coefficients were up to 80% higher than the maximum for static lift.

  13. Measuring snow water equivalent from common-offset GPR records through migration velocity analysis

    Science.gov (United States)

    St. Clair, James; Holbrook, W. Steven

    2017-12-01

    Many mountainous regions depend on seasonal snowfall for their water resources. Current methods of predicting the availability of water resources rely on long-term relationships between stream discharge and snowpack monitoring at isolated locations, which are less reliable during abnormal snow years. Ground-penetrating radar (GPR) has been shown to be an effective tool for measuring snow water equivalent (SWE) because of the close relationship between snow density and radar velocity. However, the standard methods of measuring radar velocity can be time-consuming. Here we apply a migration focusing method originally developed for extracting velocity information from diffracted energy observed in zero-offset seismic sections to the problem of estimating radar velocities in seasonal snow from common-offset GPR data. Diffractions are isolated by plane-wave-destruction (PWD) filtering and the optimal migration velocity is chosen based on the varimax norm of the migrated image. We then use the radar velocity to estimate snow density, depth, and SWE. The GPR-derived SWE estimates are within 6 % of manual SWE measurements when the GPR antenna is coupled to the snow surface and 3-21 % of the manual measurements when the antenna is mounted on the front of a snowmobile ˜ 0.5 m above the snow surface.

  14. Measuring snow water equivalent from common-offset GPR records through migration velocity analysis

    Directory of Open Access Journals (Sweden)

    J. St. Clair

    2017-12-01

    Full Text Available Many mountainous regions depend on seasonal snowfall for their water resources. Current methods of predicting the availability of water resources rely on long-term relationships between stream discharge and snowpack monitoring at isolated locations, which are less reliable during abnormal snow years. Ground-penetrating radar (GPR has been shown to be an effective tool for measuring snow water equivalent (SWE because of the close relationship between snow density and radar velocity. However, the standard methods of measuring radar velocity can be time-consuming. Here we apply a migration focusing method originally developed for extracting velocity information from diffracted energy observed in zero-offset seismic sections to the problem of estimating radar velocities in seasonal snow from common-offset GPR data. Diffractions are isolated by plane-wave-destruction (PWD filtering and the optimal migration velocity is chosen based on the varimax norm of the migrated image. We then use the radar velocity to estimate snow density, depth, and SWE. The GPR-derived SWE estimates are within 6 % of manual SWE measurements when the GPR antenna is coupled to the snow surface and 3–21 % of the manual measurements when the antenna is mounted on the front of a snowmobile  ∼  0.5 m above the snow surface.

  15. Blood flow velocity measurements in chicken embryo vascular network via PIV approach

    Science.gov (United States)

    Kurochkin, Maxim A.; Stiukhina, Elena S.; Fedosov, Ivan V.; Tuchin, Valery V.

    2018-04-01

    A method for measuring of blood velocity in the native vasculature of a chick embryo by the method of micro anemometry from particle images (μPIV) is improved. A method for interrogation regions sorting by the mask of the vasculature is proposed. A method for sorting of the velocity field of capillary blood flow is implemented. The in vitro method was evaluated for accuracy in a glass phantom of a blood vessel with a diameter of 50 μm and in vivo on the bloodstream of a chicken embryo, by comparing the transverse profile of the blood velocity obtained by the PIV method with the theoretical Poiseuille laminar flow profile.

  16. Measurements of Terminal Velocities of Cirrus Clouds in the Upper Trosphere

    Directory of Open Access Journals (Sweden)

    Nee Jan Bai

    2016-01-01

    Full Text Available Cirrus clouds are composed of ice crystals condensed from humidity due to low temperature condition in the upper atmosphere. The microphysics of cirrus clouds including sizes and shapes of ice particles are not well understood but are important in climate modeling. Ice crystal will fall under gravitational sedimentation to reach terminal velocities which depend on the size, mass, and ice habit. We studied here the terminal velocity of cirrus clouds by using lidar observations at Chungli (25N, 121E. The terminal velocities for a few cases of stable cirrus clouds are measured to determine the ice particle sizes and processes in the upper atmosphere.

  17. Measurement of velocity deficit at the downstream of a 1:10 axial hydrokinetic turbine model

    Energy Technology Data Exchange (ETDEWEB)

    Gunawan, Budi [ORNL; Neary, Vincent S [ORNL; Hill, Craig [St. Anthony Falls Laboratory, 2 Third Avenue SE, Minneapolis, MN 55414; Chamorro, Leonardo [St. Anthony Falls Laboratory, 2 Third Avenue SE, Minneapolis, MN 55414

    2012-01-01

    Wake recovery constrains the downstream spacing and density of turbines that can be deployed in turbine farms and limits the amount of energy that can be produced at a hydrokinetic energy site. This study investigates the wake recovery at the downstream of a 1:10 axial flow turbine model using a pulse-to-pulse coherent Acoustic Doppler Profiler (ADP). In addition, turbine inflow and outflow velocities were measured for calculating the thrust on the turbine. The result shows that the depth-averaged longitudinal velocity recovers to 97% of the inflow velocity at 35 turbine diameter (D) downstream of the turbine.

  18. Molecular Rayleigh Scattering Diagnostic for Dynamic Temperature, Velocity, and Density Measurements

    Science.gov (United States)

    Mielke, Amy R.; Elam, Kristie A.; Sung, Chi-Jen

    2006-01-01

    A molecular Rayleigh scattering technique is developed to measure dynamic gas temperature, velocity, and density in unseeded turbulent flows at sampling rates up to 16 kHz. A high power CW laser beam is focused at a point in an air jet plume and Rayleigh scattered light is collected and spectrally resolved. The spectrum of the light, which contains information about the temperature and velocity of the flow, is analyzed using a Fabry-Perot interferometer. The circular interference fringe pattern is divided into four concentric regions and sampled at 1 and 16 kHz using photon counting electronics. Monitoring the relative change in intensity within each region allows for measurement of gas temperature and velocity. Independently monitoring the total scattered light intensity provides a measure of gas density. A low speed heated jet is used to validate the measurement of temperature fluctuations and an acoustically excited nozzle flow is studied to validate velocity fluctuation measurements. Power spectral density calculations of the property fluctuations, as well as mean and fluctuating quantities are presented. Temperature fluctuation results are compared with constant current anemometry measurements and velocity fluctuation results are compared with constant temperature anemometry measurements at the same locations.

  19. Turbulent wind field characterization and re-generation based on pitot tube measurements mounted on a wind turbine

    DEFF Research Database (Denmark)

    Pedersen, Mads Mølgaard; Larsen, Torben J.; Aagaard Madsen, Helge

    2015-01-01

    models that compensate for axial and tangential induction, approximated by blade element momentum theory, radial expansion of the inflow, rotor tilt, dynamic and skew inflow, tip loss, as well as braking and circulation of the flow local to the airfoil. The wind speeds measured on the rotating blades...... the measured wind speeds at the recording position. In the theoretical part of this study a quite good agreement is seen between load sensors on a turbine model exposed to the reference and the re-generated turbulence field. Finally the method is applied to full scale measurements and reasonable wind shear...

  20. An experiment to measure the one-way velocity of propagation of electromagnetic radiation

    Science.gov (United States)

    Kolen, P.; Torr, D. G.

    1982-01-01

    An experiment involving commercially available instrumentation to measure the velocity of the earth with respect to absolute space is described. The experiment involves the measurement of the one-way propagation velocity of electromagnetic radiation down a high-quality coaxial cable. It is demonstrated that the experiment is both physically meaningful and exceedingly simple in concept and in implementation. It is shown that with currently available commercial equipment one might expect to detect a threshold value for the component of velocity of the earth's motion with respect to absolute space in the equatorial plane of approximately 10 km/s, which greatly exceeds the velocity resolution required to detect the motion of the solar system with respect to the center of the galaxy.

  1. Parallel ion flow velocity measurement using laser induced fluorescence method in an electron cyclotron resonance plasma

    International Nuclear Information System (INIS)

    Yoshimura, Shinji; Okamoto, Atsushi; Terasaka, Kenichiro; Ogiwara, Kohei; Tanaka, Masayoshi Y.; Aramaki, Mitsutoshi

    2010-01-01

    Parallel ion flow velocity along a magnetic field has been measured using a laser induced fluorescence (LIF) method in an electron cyclotron resonance (ECR) argon plasma with a weakly-diverging magnetic field. To measure parallel flow velocity in a cylindrical plasma using the LIF method, the laser beam should be injected along device axis; however, the reflection of the incident beam causes interference between the LIF emission of the incident and reflected beams. Here we present a method of quasi-parallel laser injection at a small angle, which utilizes the reflected beam as well as the incident beam to obtain the parallel ion flow velocity. Using this method, we observed an increase in parallel ion flow velocity along the magnetic field. The acceleration mechanism is briefly discussed on the basis of the ion fluid model. (author)

  2. Study on the influence of attitude angle on lidar wind measurement results

    Science.gov (United States)

    Han, Xiaochen; Dou, Peilin; Xue, Yangyang

    2017-11-01

    When carrying on wind profile measurement of offshore wind farm by shipborne Doppler lidar technique, the ship platform often produces motion response under the action of ocean environment load. In order to measure the performance of shipborne lidar, this paper takes two lidar wind measurement results as the research object, simulating the attitude of the ship in the ocean through the three degree of freedom platform, carrying on the synchronous observation test of the wind profile, giving an example of comparing the wind measurement data of two lidars, and carrying out the linear regression statistical analysis for all the experimental correlation data. The results show that the attitude angle will affect the precision of the lidar, The influence of attitude angle on the accuracy of lidar is uncertain. It is of great significance to the application of shipborne Doppler lidar wind measurement technology in the application of wind resources assessment in offshore wind power projects.

  3. 3D velocity measurements in fluid flows using multiple exposure holography

    International Nuclear Information System (INIS)

    Stanislas, M.; Rodriguez, O.; Dadi, M.; Beluche, F.

    1987-01-01

    An account is given of multiple exposure holography's application to the measurement of velocity in fluid flows. The method is nonintrusive, and yields access to the three components of the instantaneous velocity in three-dimensional domains. These characteristics render such holographic data complementary to classical LDV. Attention is given to solutions proposed for such limitations inherent in the method as the rather lengthy acquisition time; this difficulty is presently addressed by means of an automated evaluation methodology. 12 references

  4. Measuring the Angular Velocity of a Propeller with Video Camera Using Electronic Rolling Shutter

    Directory of Open Access Journals (Sweden)

    Yipeng Zhao

    2018-01-01

    Full Text Available Noncontact measurement for rotational motion has advantages over the traditional method which measures rotational motion by means of installing some devices on the object, such as a rotary encoder. Cameras can be employed as remote monitoring or inspecting sensors to measure the angular velocity of a propeller because of their commonplace availability, simplicity, and potentially low cost. A defect of the measurement with cameras is to process the massive data generated by cameras. In order to reduce the collected data from the camera, a camera using ERS (electronic rolling shutter is applied to measure angular velocities which are higher than the speed of the camera. The effect of rolling shutter can induce geometric distortion in the image, when the propeller rotates during capturing an image. In order to reveal the relationship between the angular velocity and the image distortion, a rotation model has been established. The proposed method was applied to measure the angular velocities of the two-blade propeller and the multiblade propeller. The experimental results showed that this method could detect the angular velocities which were higher than the camera speed, and the accuracy was acceptable.

  5. Characterization of the alumina-zirconia ceramic system by ultrasonic velocity measurements

    International Nuclear Information System (INIS)

    Carreon, Hector; Ruiz, Alberto; Medina, Ariosto; Barrera, Gerardo; Zarate, Juan

    2009-01-01

    In this work an alumina-zirconia ceramic composites have been prepared with α-Al 2 O 3 contents from 10 to 95 wt.%. The alumina-zirconia ceramic system was characterized by means of precise ultrasonic velocity measurements. In order to find out the factors affecting the variation in wave velocity, the ceramic composite have been examined by X-ray diffraction (XRD) and (SEM) scanning electron microscopy. It was found that the ultrasonic velocity measurements changed considerably with respect to the ceramic composite composition. In particular, we studied the behavior of the physical material property hardness, an important parameter of the ceramic composite mechanical properties, with respect to the variation in the longitudinal and shear wave velocities. Shear wave velocities exhibited a stronger interaction with microstructural and sub-structural features as compared to that of longitudinal waves. In particular, this phenomena was observed for the highest α-Al 2 O 3 content composite. Interestingly, an excellent correlation between ultrasonic velocity measurements and ceramic composite hardness was observed.

  6. Video imaging measurement of interfacial wave velocity in air-water flow through a horizontal elbow

    Science.gov (United States)

    Al-Wazzan, Amir; Than, Cheok F.; Moghavvemi, Mahmoud; Yew, Chia W.

    2001-10-01

    Two-phase flow in pipelines containing elbows represents a common situation in the oil and gas industries. This study deals with the stratified flow regime between the gas and liquid phase through an elbow. It is of interest to study the change in wave characteristics by measuring the wave velocity and wavelength at the inlet and outlet of the elbow. The experiments were performed under concurrent air-water stratified flow in a horizontal transparent polycarbonate pipe of 0.05m diameter and superficial air and water velocities up to 8.97 and 0.0778 m/s respectively. A non-intrusive video imaging technique was applied to capture the waves. For image analysis, a frame by frame direct overlapping method was used to detect for pulsating flow and a pixel shifting method based on the detection of minimum values in the overlap function was used to determine wave velocity and wavelength. Under superficial gas velocity of less than 4.44 m/s, the results suggest a regular pulsating outflow produced by the elbow. At higher gas velocities, more random pulsation was found and the emergence of localized interfacial waves was detected. Wave velocities measured by this technique were found to produce satisfactory agreement with direct measurements.

  7. Wind profiler mixing depth and entrainment measurements with chemical applications

    Energy Technology Data Exchange (ETDEWEB)

    Angevine, W.M.; Trainer, M.; Parrish, D.D.; Buhr, M.P.; Fehsenfeld, F.C. [NOAA Aeronomy Lab., Boulder, CO (United States); Kok, G.L. [NCAR Research Aviation Facility, Boulder, CO (United States)

    1994-12-31

    Wind profiling radars operating at 915 MHz have been present at a number of regional air quality studies. The profilers can provide a continuous, accurate record of the depth of the convective mixed layer with good time resolution. Profilers also provide information about entrainment at the boundary layer top. Mixing depth data from several days of the Rural Oxidants in the Southern Environment II (ROSE II) study in Alabama in June, 1992 are presented. For several cases, chemical measurements from aircraft and ground-based instruments are shown to correspond to mixing depth and entrainment zone behavior observed by the profiler.

  8. A novel polarization interferometer for measuring upper atmospheric winds

    International Nuclear Information System (INIS)

    Ting-Kui, Mu; Chun-Min, Zhang

    2010-01-01

    A static polarization interferometer for measuring upper atmospheric winds is presented, based on two Savart plates with their optical axes perpendicular to each other. The principle and characteristics of the interferometer are described. The interferometer with a wide field of view can offer a stable benchmark optical path difference over a specified spectral region of 0.55–0.63 μm because there are no quarter wave plates. Since the instrument employs a straight line common-path configuration but without moving parts and slits, it is very compact, simple, inherently robust and has high throughput. The paper is limited to a theoretical analysis. (general)

  9. Nearly simultaneous measurements of radar auroral heights and Doppler velocities at 398 MHz

    International Nuclear Information System (INIS)

    Moorcroft, D.; Ruohoniemi, J.M.

    1987-01-01

    Nearly simultaneous measurements of radar auroral heights and Doppler velocities were obtained using the Homer, Alaska, 398-MHz phased-array radar over a total of 16 hours on four different days. The heights show a consistent variation with time, being highest near the time of electrojet current reversal, and lowest late in the morning. A variety of east-west height asymmetries were observed, different from those previously reported, which can be explained in terms of favorable flow angles preferentially favoring high-altitude primary two-stream waves to one side of the field of view. Low-velocity echoes, presumably due to secondary irregularities, are found to be more restricted in height range than echoes with ion acoustic velocities, which presumably come from primary two-stream instabilities. Echo power was examined as a function of velocity and height. For the westward electrojet it was found that echoes with ion acoustic velocities are relatively constant in strength over most of their height range, but for low-velocity echoes the power is a maximum between 100 and 105 km and falls off steadily at greater heights. Doppler speeds show a noticeable decrease at heights below 105 km, in agreement with the expected variation in ion acoustic velocity

  10. Volumetric velocity measurements in restricted geometries using spiral sampling: a phantom study.

    Science.gov (United States)

    Nilsson, Anders; Revstedt, Johan; Heiberg, Einar; Ståhlberg, Freddy; Bloch, Karin Markenroth

    2015-04-01

    The aim of this study was to evaluate the accuracy of maximum velocity measurements using volumetric phase-contrast imaging with spiral readouts in a stenotic flow phantom. In a phantom model, maximum velocity, flow, pressure gradient, and streamline visualizations were evaluated using volumetric phase-contrast magnetic resonance imaging (MRI) with velocity encoding in one (extending on current clinical practice) and three directions (for characterization of the flow field) using spiral readouts. Results of maximum velocity and pressure drop were compared to computational fluid dynamics (CFD) simulations, as well as corresponding low-echo-time (TE) Cartesian data. Flow was compared to 2D through-plane phase contrast (PC) upstream from the restriction. Results obtained with 3D through-plane PC as well as 4D PC at shortest TE using a spiral readout showed excellent agreements with the maximum velocity values obtained with CFD (spiral sequences were respectively 14 and 13 % overestimated compared to CFD. Identification of the maximum velocity location, as well as the accurate velocity quantification can be obtained in stenotic regions using short-TE spiral volumetric PC imaging.

  11. Estimating the Wind Resource in Uttarakhand: Comparison of Dynamic Downscaling with Doppler Lidar Wind Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Lundquist, J. K. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Pukayastha, A. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Martin, C. [Univ. of Colorado, Boulder, CO (United States); Newsom, R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2014-03-01

    Previous estimates of the wind resources in Uttarakhand, India, suggest minimal wind resources in this region. To explore whether or not the complex terrain in fact provides localized regions of wind resource, the authors of this study employed a dynamic down scaling method with the Weather Research and Forecasting model, providing detailed estimates of winds at approximately 1 km resolution in the finest nested simulation.

  12. Accounting for the speed shear in wind turbine power performance measurement

    DEFF Research Database (Denmark)

    Wagner, Rozenn; Courtney, Michael; Gottschall, Julia

    2011-01-01

    The current IEC standard for wind turbine power performance measurement only requires measurement of the wind speed at hub height assuming this wind speed to be representative for the whole rotor swept area. However, the power output of a wind turbine depends on the kinetic energy flux, which...... itself depends on the wind speed profile, especially for large turbines. Therefore, it is important to characterize the wind profile in front of the turbine, and this should be preferably achieved by measuring the wind speed over the vertical range between lower and higher rotor tips. In this paper, we...... describe an experiment in which wind speed profiles were measured in front of a multimegawatt turbine using a ground–based pulsed lidar. Ignoring the vertical shear was shown to overestimate the kinetic energy flux of these profiles, in particular for those deviating significantly from a power law profile...

  13. Particle image velocimetry measurements of 2-dimensional velocity field around twisted tape

    Energy Technology Data Exchange (ETDEWEB)

    Song, Min Seop; Park, So Hyun; Kim, Eung Soo, E-mail: kes7741@snu.ac.kr

    2016-11-01

    Highlights: • Measurements of the flow field in a pipe with twisted tape were conducted by particle image velocimetry (PIV). • A novel matching index of refraction technique utilizing 3D printing and oil mixture was adopted to make the test section transparent. • Undistorted particle images were clearly captured in the presence of twisted tape. • 2D flow field in the pipe with twisted tape revealed the characteristic two-peak velocity profile. - Abstract: Twisted tape is a passive component used to enhance heat exchange in various devices. It induces swirl flow that increases the mixing of fluid. Thus, ITER selected the twisted tape as one of the candidates for turbulence promoting in the divertor cooling. Previous study was mainly focused on the thermohydraulic performance of the twisted tape. As detailed data on the velocity field around the twisted tape was insufficient, flow visualization study was performed to provide fundamental data on velocity field. To visualize the flow in a complex structure, novel matching index of refraction technique was used with 3-D printing and mixture of anise and mineral oil. This technique enables the camera to capture undistorted particle image for velocity field measurement. Velocity fields at Reynolds number 1370–9591 for 3 different measurement plane were obtained through particle image velocimetry. The 2-dimensional averaged velocity field data were obtained from 177 pair of instantaneous velocity fields. It reveals the characteristic two-peak flow motion in axial direction. In addition, the normalized velocity profiles were converged with increase of Reynolds numbers. Finally, the uncertainty of the result data was analyzed.

  14. Velocity of sound measurements in gaseous per-fluorocarbons and their custom mixtures

    CERN Document Server

    Vacek, V; Lindsay, S

    2000-01-01

    An inexpensive sonar instrument was prepared for measurements of sound velocity in two fluorocarbon vapors; per-fluoro-n-propane (C3F8), per-fluoro-n-butane (C4F10), and their custom mixtures. The apparatus, measurement principle and instrument software are described. All sound velocity measurements in per-fluorocarbons were made in the low pressure range between 0.01 and 0.4 MPa, and at temperatures between 253 and 303 K. The purity of the C3F8 and C4F10 samples was checked using gas chromatography. Uncertainties in the speed of sound measurements were better than ± 0.1 %. Comparisons were made with theoretical predictions of sound velocity for the two individual components. The instrument was then used for concentration monitoring of custom C3F8/C4F10 mixtures.

  15. Ultrasonic velocity measurements- a potential sensor for intelligent processing of austenitic stainless steels

    International Nuclear Information System (INIS)

    Venkadesan, S.; Palanichamy, P.; Vasudevan, M.; Baldev Raj

    1996-01-01

    Development of sensors based on Non-Destructive Evaluation (NDE) techniques for on-line sensing of microstructure and properties requires a thorough knowledge on the relation between the sensing mechanism/measurement of an NDE technique and the microstructure. As a first step towards developing an on-line sensor for studying the dynamic microstructural changes during processing of austenitic stainless steels, ultrasonic velocity measurements have been carried out to study the microstructural changes after processing. Velocity measurements could follow the progress of annealing starting from recovery, onset and completion of recrystallization, sense the differences in the microstructure obtained after hot deformation and estimate the grain size. This paper brings out the relation between the sensing method based on ultrasonic velocity measurements and the microstructure in austenitic stainless steel. (author)

  16. Liner velocity, current, and symmetry measurements on the 32 MA flux compression generator experiment ALT-1

    CERN Document Server

    Clark, D A; Rodríguez, G; Tabaka, L J

    2001-01-01

    Summary form only given, as follows. A flux compression generator based pulse power system, designed, built, and fielded by a Russian team at the All Russian Scientific Research Institute of Experimental Physics (VNIIEF), was used to successfully drive an aluminum liner to velocities greater than 10 km/sec. The experiment objective was to demonstrate performance of a precision liner implosion at Atlas current of 30 MA or greater. Diagnostics to measure liner performance were an essential part of the experiment. An experimental team from Los Alamos National Laboratory (LANL) provided a suite of diagnostics to measure liner performance. Three diagnostics were fielded. 1. a velocity interferometer (VISAR) to continuously measure the liner inner surface velocity from throughout the entire range of travel. 2. Two Faraday rotation devices to measure liner current during the implosion. 3. Sixteen fiber optic impact pins to record liner impact time and provide axial and azimuthal symmetry information. All diagnostics...

  17. Wind turbine power and sound in relation to atmospheric stability

    NARCIS (Netherlands)

    van den Berg, G. P.

    2008-01-01

    Atmospheric stability cannot, with respect to modem, toll wind turbines, be viewed as a 'small perturbation to a basic neutral state' This can be demonstrated by comparison of measured wind velocity at the height of the rotor with the wind velocity expected in a neutral or 'standard' atmosphere.

  18. Progress on High-Energy 2-micron Solid State Laser for NASA Space-Based Wind and Carbon Dioxide Measurements

    Science.gov (United States)

    Singh, Upendra N.

    2011-01-01

    Sustained research efforts at NASA Langley Research Center during last fifteen years have resulted in significant advancement of a 2-micron diode-pumped, solid-state laser transmitter for wind and carbon dioxide measurements from ground, air and space-borne platforms. Solid-state 2-micron laser is a key subsystem for a coherent Doppler lidar that measures the horizontal and vertical wind velocities with high precision and resolution. The same laser, after a few modifications, can also be used in a Differential Absorption Lidar system for measuring atmospheric CO2 concentration profiles. Researchers at NASA Langley Research Center have developed a compact, flight capable, high energy, injection seeded, 2-micron laser transmitter for ground and airborne wind and carbon dioxide measurements. It is capable of producing 250 mJ at 10 Hz by an oscillator and one amplifier. This compact laser transmitter was integrated into a mobile trailer based coherent Doppler wind and CO2 DIAL system and was deployed during field measurement campaigns. This paper will give an overview of 2-micron solid-state laser technology development and discuss results from recent ground-based field measurements.

  19. Videometric research on deformation measurement of large-scale wind turbine blades

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Utilization of wind energy is a promising way to generate power,and wind turbine blades play a key role in collecting the wind energy effectively.This paper attempts to measure the deformation parameter of wind turbine blades in mechanics experiments using a videometric method. In view that the blades experience small buckling deformation and large integral deformation simultaneously, we proposed a parallel network measurement(PNM) method including the key techniques such as camera network construction,c...

  20. Improved measurements of mean sea surface velocity in the Nordic Seas from synthetic aperture radar

    Science.gov (United States)

    Wergeland Hansen, Morten; Johnsen, Harald; Engen, Geir; Øie Nilsen, Jan Even

    2017-04-01

    The warm and saline surface Atlantic Water (AW) flowing into the Nordic Seas across the Greenland-Scotland ridge transports heat into the Arctic, maintaining the ice-free oceans and regulating sea-ice extent. The AW influences the region's relatively mild climate and is the northern branch of the global thermohaline overturning circulation. Heat loss in the Norwegian Sea is key for both heat transport and deep water formation. In general, the ocean currents in the Nordic Seas and the North Atlantic Ocean is a complex system of topographically steered barotropic and baroclinic currents of which the wind stress and its variability is a driver of major importance. The synthetic aperture radar (SAR) Doppler centroid shift has been demonstrated to contain geophysical information about sea surface wind, waves and current at an accuracy of 5 Hz and pixel spacing of 3.5 - 9 × 8 km2. This corresponds to a horizontal surface velocity of about 20 cm/s at 35° incidence angle. The ESA Prodex ISAR project aims to implement new and improved SAR Doppler shift processing routines to enable reprocessing of the wide swath acquisitions available from the Envisat ASAR archive (2002-2012) at higher resolution and better accuracy than previously obtained, allowing combined use with Sentinel-1 and Radarsat-2 retrievals to build timeseries of the sea surface velocity in the Nordic Seas. Estimation of the geophysical Doppler shift from new SAR Doppler centroid shift retrievals will be demonstrated, addressing key issues relating to geometric (satellite orbit and attitude) and electronic (antenna mis-pointing) contributions and corrections. Geophysical Doppler shift retrievals from one month of data in January 2010 and the inverted surface velocity in the Nordic Seas are then addressed and compared to other direct and indirect estimates of the upper ocean current, in particular those obtained in the ESA GlobCurrent project.

  1. A first comparison of irregularity and ion drift velocity measurements in the E-region

    Directory of Open Access Journals (Sweden)

    R. A. Makarevich

    2006-09-01

    Full Text Available E-region irregularity velocity measurements at large flow angles with the STARE Finland coherent VHF radar are considered in context of the ion and electron velocity data provided by the EISCAT tristatic radar system, CUTLASS Finland coherent HF radar, and IMAGE fluxgate magnetometers. The data have been collected during a special experiment on 27 March 2004 during which EISCAT was scanning between several E- and one F-region altitudes along the magnetic field line. Within the E-region, the EISCAT measurements at two altitudes of 110 and 115 km are considered while the electron velocity is inferred from the EISCAT ion velocity measurements at 278 km. The line-of-sight (l-o-s VHF velocity measured by STARE VHF los is compared to the ion and electron velocity components (Vi0 comp and Ve0 comp along the STARE l-o-s direction. The comparison with Ve0 comp for the entire event shows that the measurements exhibit large scatter and small positive correlation. The correlation with Ve0 comp was substantial in the first half of the interval under study when Ve0 comp was larger in magnitude. The comparison with Vi0 comp at 110 and 115 km shows a considerable positive correlation, with VHF velocity being typically larger (smaller in magnitude than Vi0 comp at 110 km (115 km so that VVHF los appears to be bounded by the ion velocity components at two altitudes. It is also demonstrated that the difference between VVHF los and Vi0 comp at 110 km can be treated, in the first approximation, as a linear function of the effective backscatter height heff also counted from 110 km; heff varies in the range 108–114 km due to the altitude integration effects in the scattering cross-section. Our results are consistent with the notion that VHF

  2. Simultaneous measurement of particle and fluid velocities in particle-laden flows

    International Nuclear Information System (INIS)

    Jin, D. X.; Lee, D. Y.

    2009-01-01

    For the velocity measurement in a particle-laden fluid flow, the fluid velocity and the inherently dispersed particle velocity can be analyzed by using PIV and PTV, respectively. Since the PIV result statistically represents the average displacement of all the particles in a PIV image, it is inevitable that the PIV result includes the influence of the dispersed particles' displacement if a single CCD camera is used to simultaneously measure the fluid velocity and the dispersed particle velocity. The influence of dispersed particles should be excluded before the PIV analysis in order to evaluate the fluid velocity accurately. In this study, the optimum replacement brightness of dispersed particles to minimize the false influence of dispersed particles on the PIV analysis was theoretically derived. Simulation results show that the modification of dispersed particle brightness can significantly reduce the PIV error caused by the dispersed particles. This modification method was also verified in the analysis of an actual experimental case of the particle-laden fluid flow in a triangular grooved channel

  3. High resolution measurement of the velocity profiles of channel flows using the particle image velocimetry technique

    International Nuclear Information System (INIS)

    Nor Azizi Mohamed

    2000-01-01

    The high resolution velocity profiles of a uniform steady channel flow and a flow beneath waves were obtained using the particle image velocimetry (PIV) technique. The velocity profiles for each flow were calculated for both components. It is shown that the profiles obtained are very precise, displaying the point velocities from a few millimeters from the bottom of the channel up to the water surface across the water depth. In the case of the wave-induced flow, the profiles are shown under the respective wave phases and given in a plane representation. High resolution measurement of point velocities in a flow is achievable using PIV and invaluable when applied to a complex flow. (Author)

  4. Determination of the Ion Velocity Distribution in a Rotating Plasma from Measurements of Doppler Broadening

    DEFF Research Database (Denmark)

    Jørgensen, L. W.; Sillesen, Alfred Hegaard

    1979-01-01

    The Doppler-broadened profile of the He II 4685.75 AA line was measured along a chord in a rotating plasma, transverse to the magnetic field. Using a single-particle orbit picture, the corresponding velocity spectrum of ions confirm the measurements, so it can be concluded that the single-particl...

  5. The Lidar Cyclops Syndrome Bypassed: 3D Wind Field Measurements from a Turbine mounted Lidar in combination with a fast CFD solver

    DEFF Research Database (Denmark)

    Mikkelsen, Torben Krogh; Astrup, Poul; van Dooren, Marijn Floris

    as the “Lidar Cyclops syndrome” with reference to the one-eyed Cyclops in old Greek mythology. However, by feeding a single lidar’s line-of-sight (LOS) rotor plane scanned wind speeds to a fast CFD solver, it has been possible to determine the entire 3D velocity vectors at each measurement point consistent...

  6. FY 1999 achievement report on the supporting project to form energy/environmental technology verification project - International joint verification research project. Development of the mean wind velocity prediction method and the related matters in developing countries; 1999 nendo hatten tojokoku ni oikeru heikin fusoku yosoku shuho nado no kaihatsu seika hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    Developing countries have no sufficient basic data for the analysis of meteorological conditions including wind characteristics, and there are problems in adopting simulation models there. Accordingly, the revision/development of simulation models were conducted, considering characteristics of models to predict wind characteristics from topographical/geographical aspects and widely meteorological aspect in Myanmar. At the same time, the mean wind velocity distribution chart for Myanmar was drawn up by observing wind characteristics domestically in Myanmar, by comparing the predicted results using the above-mentioned models and the measured data, and by verifying the simulation results. The items for development are as follows: (1) To make simulation models for wind characteristics in the whole Myanmar based on the information obtained from the meteorological observation system for prediction of the mean wind velocity. Also to verify the simulational results using the measured data on wind characteristics at specified points. (2) To conduct the developmental work under a research system jointly with the counterpart and to produce favorable results as an international joint research. (3) To acquire the basic data to find the relation between the photovoltaic power generation and wind characteristics for studying hybrid type power systems for renewable energy in the future. (NEDO)

  7. Measurement for the MLC leaf velocity profile by considering the leaf leakage using a radiographic film

    International Nuclear Information System (INIS)

    Chow, James C L; Grigorov, Grigor N

    2006-01-01

    A method to measure the velocity profile of a multi-leaf collimator (MLC) leaf along its travel range using a radiographic film is reported by considering the intra-leaf leakage. A specific dynamic MLC field with leaves travelling from the field edge to the isocentre line was designed. The field was used to expose a radiographic film, which was then scanned, and the dose profile along the horizontal leaf axis was measured. The velocity at a sampling point on the film can be calculated by considering the horizontal distance between the sampling point and the isocentre line, dose at the sampling point, dose rate of the linear accelerator, the total leaf travel time from the field edge to isocentre line and the pre-measured dose rate of leaf leakage. With the leaf velocities and velocity profiles for all MLC leaves measured routinely, a comprehensive and simple QA for the MLC can be set up to test the consistency of the leaf velocity performance which is essential to the IMRT delivery using a sliding window technique. (note)

  8. Pulmonary branch arterial flow can be measured with cine MR velocity mapping

    International Nuclear Information System (INIS)

    Caputo, G.R.; Kondo, C.; Masui, T.; Foster, E.; Geraci, S.J.; O'Sullivan, M.; Higgins, C.B.

    1990-01-01

    This paper assesses the capability of cine MR phase velocity mapping (CVM) to measure main, right-sided, and left-sided pulmonary arterial (PA) blood flow. The authors examined a constant-flow phantom and nine healthy volunteers with use of 1.5-T MR imaging system (GE Signa) with phase velocity cine sequences. CVM correctly measured constant-flow phantom velocities (range, 20-190 cm/sec; r = .998, SEE = 4.2 cm/sec), and velocity with use of angulated planes to section the phantom tube perpendicularly. CVM peak systolic main PA velocity (79 cm/sec ± 10) correlated well with Doppler US measurements (80 cm/sec ± 7). CVM main PA flow correlated well with conventional cine MR LV stroke volume measurements (r = .98, SEE = 4.8 mL). Left and right PA flow on the angulated planes were 29 mL ± 7 and 34 mL ± 10, respectively

  9. Helioseismic measurements in the solar envelope using group velocities of surface waves

    Science.gov (United States)

    Vorontsov, S. V.; Baturin, V. A.; Ayukov, S. V.; Gryaznov, V. K.

    2014-07-01

    At intermediate- and high-degree l, solar p and f modes can be considered as surface waves. Using variational principle, we derive an integral expression for the group velocities of the surface waves in terms of adiabatic eigenfunctions of normal modes, and address the benefits of using group-velocity measurements as a supplementary diagnostic tool in solar seismology. The principal advantage of using group velocities, when compared with direct analysis of the oscillation frequencies, comes from their smaller sensitivity to the uncertainties in the near-photospheric layers. We address some numerical examples where group velocities are used to reveal inconsistencies between the solar models and the seismic data. Further, we implement the group-velocity measurements to the calibration of the specific entropy, helium abundance Y, and heavy-element abundance Z in the adiabatically stratified part of the solar convective envelope, using different recent versions of the equation of state. The results are in close agreement with our earlier measurements based on more sophisticated analysis of the solar oscillation frequencies. These results bring further support to the downward revision of the solar heavy-element abundances in recent spectroscopic measurements.

  10. On-line velocity measurements using phase probes at the SuperHILAC

    International Nuclear Information System (INIS)

    Feinberg, B.; Meaney, D.; Thatcher, R.; Timossi, C.

    1987-12-01

    Phase probes have been placed in several external beam lines at the LBL heavy ion linear accelerator (SuperHILAC) to provide non- destructive velocity measurements independent of the ion being accelerated. The system uses three probes in each line to obtain accurate velocity measurements at all beam energies. Automatic gain control and signal analysis are performed so that the energy/nucleon along with up to three probe signals are displayed on a vector graphics display with a refresh rate better than twice per second. The system uses a sensitive pseudo-correlation technique to pick out the signal from the noise, features simultaneous measurements of up to four ion velocities when more than one beam is being accelerated, and is controlled by a touch-screen operator interface. It is accurate to within /+-/0.25% and has provisions for on-line calibration tests. The phase probes thus provide a velocity measurement independent of the mass defect associated with the use of crystal detectors, which can become significant for heavy elements. They are now used as a routine tuning aid to ensure proper bunch structure, and as a beam velocity monitor. 3 refs., 5 figs

  11. Development of Autonomous Boat-Type Robot for Automated Velocity Measurement in Straight Natural River

    Science.gov (United States)

    Sanjou, Michio; Nagasaka, Tsuyoshi

    2017-11-01

    The present study describes an automated system to measure the river flow velocity. A combination of the camera-tracking system and the Proportional/Integral/Derivative (PID) control could enable the boat-type robot to remain in position against the mainstream; this results in reasonable evaluation of the mean velocity by a duty ratio which corresponds to rotation speed of the screw propeller. A laser range finder module was installed to measure the local water depth. Reliable laboratory experiments with the prototype boat robot and electromagnetic velocimetry were conducted to obtain a calibration curve that connects the duty ratio and mean current velocity. The remaining accuracy in the target point was also examined quantitatively. The fluctuation in the spanwise direction is within half of the robot length. It was therefore found that the robot remains well within the target region. We used two-dimensional navigation tests to guarantee that the prototype moved smoothly to the target points and successfully measured the streamwise velocity profiles across the mainstream. Moreover, the present robot was found to move successfully not only in the laboratory flume but also in a small natural river. The robot could move smoothly from the starting point near the operator's site toward the target point where the velocity is measured, and it could evaluate the cross-sectional discharge.

  12. Upgrading the Arecibo Potassium Lidar Receiver for Meridional Wind Measurements

    Science.gov (United States)

    Piccone, A. N.; Lautenbach, J.

    2017-12-01

    Lidar can be used to measure a plethora of variables: temperature, density of metals, and wind. This REU project is focused on the set up of a semi steerable telescope that will allow the measurement of meridional wind in the mesosphere (80-105 km) with Arecibo Observatory's potassium resonance lidar. This includes the basic design concept of a steering system that is able to turn the telescope to a maximum of 40°, alignment of the mirror with the telescope frame to find the correct focusing, and the triggering and programming of a CCD camera. The CCD camera's purpose is twofold: looking though the telescope and matching the stars in the field of view with a star map to accurately calibrate the steering system and determining the laser beam properties and position. Using LabVIEW, the frames from the CCD camera can be analyzed to identify the most intense pixel in the image (and therefore the brightest point in the laser beam or stars) by plotting average pixel values per row and column and locating the peaks of these plots. The location of this pixel can then be plotted, determining the jitter in the laser and position within the field of view of the telescope.

  13. Measurement of transient two-phase flow velocity using statistical signal analysis of impedance probe signals

    International Nuclear Information System (INIS)

    Leavell, W.H.; Mullens, J.A.

    1981-01-01

    A computational algorithm has been developed to measure transient, phase-interface velocity in two-phase, steam-water systems. The algorithm will be used to measure the transient velocity of steam-water mixture during simulated PWR reflood experiments. By utilizing signals produced by two, spatially separated impedance probes immersed in a two-phase mixture, the algorithm computes the average transit time of mixture fluctuations moving between the two probes. This transit time is computed by first, measuring the phase shift between the two probe signals after transformation to the frequency domain and then computing the phase shift slope by a weighted least-squares fitting technique. Our algorithm, which has been tested with both simulated and real data, is able to accurately track velocity transients as fast as 4 m/s/s

  14. Velocity Field Measurements of Human Coughing Using Time Resolved Particle Image Velocimetry

    Science.gov (United States)

    Khan, T.; Marr, D. R.; Higuchi, H.; Glauser, M. N.

    2003-11-01

    Quantitative fluid mechanics analysis of human coughing has been carried out using new Time Resolved Particle Image Velocimetry (TRPIV). The study involves measurement of velocity vector time-histories and velocity profiles. It is focused on the average normal human coughing. Some work in the past on cough mechanics has involved measurement of flow rates, tidal volumes and sub-glottis pressure. However, data of unsteady velocity vector field of the exiting highly time-dependent jets is not available. In this study, human cough waveform data are first acquired in vivo using conventional respiratory instrumentation for various volunteers of different gender/age groups. The representative waveform is then reproduced with a coughing/breathing simulator (with or without a manikin) for TRPIV measurements and analysis. The results of this study would be useful not only for designing of indoor air quality and heating, ventilation and air conditioning systems, but also for devising means of protection against infectious diseases.

  15. Trajectory and velocity measurement of a particle in spray by digital holography

    Energy Technology Data Exchange (ETDEWEB)

    Lue Qieni; Chen Yiliang; Yuan Rui; Ge Baozhen; Gao Yan; Zhang Yimo

    2009-12-20

    We present a method for the trajectory and the velocity measurement of a particle in spray by digital holography. Based on multiple exposure digital in-line holography, a sequence of digital holograms of a dynamic spray particle field at different times are recorded with a CW laser and a high-speed CCD. The time evolution of the serial positions of particles, i.e., the motion trajectories of the particles, is obtained by numerically reconstructing the synthetic hologram of a sequence of digital holograms. The center coordinate (x,y) of each particle image can be extracted using a Hough transform and subpixel precision computing, and the velocity of an individual particle can also be obtained, which is then applied to measuring the velocity of diesel spray and alcohol spray. The research shows that the method presented in this paper for measuring spray field is feasible.

  16. Simultaneous measurement of particle velocity and size based on gray difference and autocorrelation

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The gray of two images of a same particle taken by a digital camera with different exposure times is different too. Based on the gray difference of particle images in a double-exposed photo and autocorrelation processing of digital images,this paper proposes a method for measuring particle velocities and sizes simultaneously. This paper also introduces the theoretical foundation of this method,the process of particle imaging and image processing,and the simultaneous measurement of velocity and size of a low speed flow field with 35 μm and 75 μm standard particles. The graphical measurement results can really reflect the flow characteristics of the flow field. In addition,although the measured velocity and size histograms of these two kinds of standard particles are slightly wider than the theoretical ones,they are all still similar to the normal distribution,and the peak velocities and diameters of the histograms are consistent with the default values. Therefore,this measurement method is capable of providing moderate measurement accuracy,and it can be further developed for high-speed flow field measurements.

  17. Solar Wind Halo Formation by the Scattering of the Strahl via Direct Cluster/PEACE Observations of the 3D Velocity Distribution Function

    Science.gov (United States)

    Figueroa-Vinas, Adolfo; Gurgiolo, Chris A.; Nieves-Chinchilla, Teresa; Goldstein, Melvyn L.

    2010-01-01

    It has been suggested by a number of authors that the solar wind electron halo can be formed by the scattering of the strahl. On frequent occasions we have observed in electron angular skymaps (Phi/Theta-plots) of the electron 3D velocity distribution functions) a bursty-filament of particles connecting the strahl to the solar wind core-halo. These are seen over a very limited energy range. When the magnetic field is well off the nominal solar wind flow direction such filaments are inconsistent with any local forces and are probably the result of strong scattering. Furthermore, observations indicates that the strahl component is frequently and significantly anisotropic (Tper/Tpal approx.2). This provides a possible free energy source for the excitation of whistler waves as a possible scattering mechanism. The empirical observational evidence between the halo and the strahl suggests that the strahl population may be, at least in part, the source of the halo component.

  18. Probabilistic distributions of wind velocity for the evaluation of the wind power potential; Distribuicoes probabilisticas de velocidades do vento para avaliacao do potencial energetico eolico

    Energy Technology Data Exchange (ETDEWEB)

    Vendramini, Elisa Zanuncio

    1986-10-01

    The theoretical model of wind speed distributions allow valuable information about the probability of events relative to the variable in study eliminating the necessity of a new experiment. The most used distributions has been the Weibull and the Rayleigh. These distributions are examined in the present investigation, as well as the exponential, gamma, chi square and lognormal distributions. Three years of hourly averages wind data recorded from a anemometer setting at the city of Ataliba Leonel, Sao Paulo State, Brazil, were used. Using wind speed distribution the theoretical relative frequency was calculated from the distributions which have been examined. Results from the Kolmogorov - Smirnov test allow to conclude that the lognormal distribution fit better the wind speed data, followed by the gamma and Rayleigh distributions. Using the lognormal probability density function the yearly energy output from a wind generator installed in the side was calculated. 30 refs, 4 figs, 14 tabs

  19. Exploring the nearshore marine wind profile from field measurements and numerical hindcast

    Science.gov (United States)

    del Jesus, F.; Menendez, M.; Guanche, R.; Losada, I.

    2012-12-01

    Wind power is the predominant offshore renewable energy resource. In the last years, offshore wind farms have become a technically feasible source of electrical power. The economic feasibility of offshore wind farms depends on the quality of the offshore wind conditions compared to that of onshore sites. Installation and maintenance costs must be balanced with more hours and a higher quality of the available resources. European offshore wind development has revealed that the optimum offshore sites are those in which the distance from the coast is limited with high available resource. Due to the growth in the height of the turbines and the complexity of the coast, with interactions between inland wind/coastal orography and ocean winds, there is a need for field measurements and validation of numerical models to understand the marine wind profile near the coast. Moreover, recent studies have pointed out that the logarithmic law describing the vertical wind profile presents limitations. The aim of this work is to characterize the nearshore vertical wind profile in the medium atmosphere boundary layer. Instrumental observations analyzed in this work come from the Idermar project (www.Idermar.es). Three floating masts deployed at different locations on the Cantabrian coast provide wind measurements from a height of 20 to 90 meters. Wind speed and direction are measured as well as several meteorological variables at different heights of the profile. The shortest wind time series has over one year of data. A 20 year high-resolution atmospheric hindcast, using the WRF-ARW model and focusing on hourly offshore wind fields, is also analyzed. Two datasets have been evaluated: a European reanalysis with a ~15 Km spatial resolution, and a hybrid downscaling of wind fields with a spatial resolution of one nautical mile over the northern coast of Spain.. These numerical hindcasts have been validated based on field measurement data. Several parameterizations of the vertical wind

  20. A FULL-SCALE MEASUREMENT OF WIND ACTIONS AND EFFECTS ON A SEA-CROSSING BRIDGE

    Directory of Open Access Journals (Sweden)

    Yi Zhou

    2017-10-01

    Full Text Available Wind loading is critical for the large-span and light-weight structures, and field measurement is the most effective way to evaluate the wind resistance performance of a specific structure. This study investigates the wind characteristics and wind-induced vibration on a sea-crossing bridge in China, namely Donghai Bridge, based on up to six years of monitoring data. It is found that: (1 there exists obvious discrepancy between the measured wind field parameters and the values suggested by the design code; and the wind records at the bridge site is easily interfered by the bridge structure itself, which should be considered in interpreting the measurements and designing structural health monitoring systems (SHMS; (2 for strong winds with high non-stationarity, a shorter averaging time than 10-min is preferable to obtain more stable turbulent wind characteristics; (3 the root mean square (RMS of the wind-induced acceleration of the girder may increase in an approximately quadratic curve relationship with the mean wind speed; and (4 compared to traffic load, the wind dominates the girder’s lateral vibration amplitude, while the heavy-load traffic might exert more influence on the girder’s vertical and torsional vibrations than the high winds. This study provides field evidence for the wind-resistant design and evaluation of bridges in similar operational conditions.

  1. Estimated carotid-femoral pulse wave velocity has similar predictive value as measured carotid-femoral pulse wave velocity

    DEFF Research Database (Denmark)

    Greve, Sara V; Blicher, Marie K; Kruger, Ruan

    2016-01-01

    BACKGROUND: Carotid-femoral pulse wave velocity (cfPWV) adds significantly to traditional cardiovascular risk prediction, but is not widely available. Therefore, it would be helpful if cfPWV could be replaced by an estimated carotid-femoral pulse wave velocity (ePWV) using age and mean blood pres...... that these traditional risk scores have underestimated the complicated impact of age and blood pressure on arterial stiffness and cardiovascular risk....

  2. Wind Turbine Performance Measurements by Means of Dynamic Data Analysis

    DEFF Research Database (Denmark)

    Friis Pedersen, Troels; Wagner, Rozenn; Demurtas, Giorgio

    tools have been developed by authors to try to make the drift field and fixed point determination more robust. A sensitivity analysis with nacelle lidar data showed drift determination was not very dependent on the time steps applied, leading to use of time steps of 2-3 points for each dataset. Power...... bin size should be fixed. Data averaging with 5 sec data was more distinct for determination of the fixed points than 2 and 1 sec data. With the nacelle lidar the Langevin method seemed to produce a power curve that was comparable to the IEC power curve. Analysis of the Langevin method with spinner...... curves could be made faster with 1Hz dataset. In the FastWind project the Langevin power curve method was used on real power curve measurement datasets with the purpose to evaluate the method for practical use. A practical guide to application of the method to real power curve measurement data was made...

  3. Frequency swept fibre laser for wind speed measurements

    DEFF Research Database (Denmark)

    Pedersen, Anders Tegtmeier

    This PhD thesis builds around a light source forming the basis for a novel type of wind measuring lidar. The lidar emits a train of laser pulses with each pulse being separated from its neighbours in frequency, while being closely spaced in time, thus combining the advantages of conventional...... continuous wave (CW) and pulsed lidars. A light source capable of emitting such a pulse train is suggested. A theoretical description of all components constituting the light source is presented, and a time dependent model is developed and compared to measurements as well as to previous theoretical work from...... the scientific literature. The model presented shows good agreement with the experimental results regarding the pulse train envelope as well as the individual pulses. A model adopted from the literature is subsequently expanded to incorporate frequency components other than the main signal frequency and compared...

  4. Immersed transient eddy current flow metering: a calibration-free velocity measurement technique for liquid metals

    Science.gov (United States)

    Krauter, N.; Stefani, F.

    2017-10-01

    Eddy current flow meters are widely used for measuring the flow velocity of electrically conducting fluids. Since the flow induced perturbations of a magnetic field depend both on the geometry and the conductivity of the fluid, extensive calibration is needed to get accurate results. Transient eddy current flow metering has been developed to overcome this problem. It relies on tracking the position of an impressed eddy current system that is moving with the same velocity as the conductive fluid. We present an immersed version of this measurement technique and demonstrate its viability by numerical simulations and a first experimental validation.

  5. Retinal hemodynamic oxygen reactivity assessed by perfusion velocity, blood oximetry and vessel diameter measurements

    DEFF Research Database (Denmark)

    Klefter, Oliver Niels; Lauritsen, Anne Øberg; Larsen, Michael

    2015-01-01

    PURPOSE: To test the oxygen reactivity of a fundus photographic method of measuring macular perfusion velocity and to integrate macular perfusion velocities with measurements of retinal vessel diameters and blood oxygen saturation. METHODS: Sixteen eyes in 16 healthy volunteers were studied at two...... is a valid method for assessing macular perfusion. Results were consistent with previous observations of hyperoxic blood flow reduction using blue field entoptic and laser Doppler velocimetry. Retinal perfusion seemed to be regulated around individual set points according to blood glucose levels. Multimodal...

  6. Immersed transient eddy current flow metering: a calibration-free velocity measurement technique for liquid metals

    International Nuclear Information System (INIS)

    Krauter, N; Stefani, F

    2017-01-01

    Eddy current flow meters are widely used for measuring the flow velocity of electrically conducting fluids. Since the flow induced perturbations of a magnetic field depend both on the geometry and the conductivity of the fluid, extensive calibration is needed to get accurate results. Transient eddy current flow metering has been developed to overcome this problem. It relies on tracking the position of an impressed eddy current system that is moving with the same velocity as the conductive fluid. We present an immersed version of this measurement technique and demonstrate its viability by numerical simulations and a first experimental validation. (paper)

  7. Validity and reliability of simple measurement device to assess the velocity of the barbell during squats.

    Science.gov (United States)

    Lorenzetti, Silvio; Lamparter, Thomas; Lüthy, Fabian

    2017-12-06

    The velocity of a barbell can provide important insights on the performance of athletes during strength training. The aim of this work was to assess the validity and reliably of four simple measurement devices that were compared to 3D motion capture measurements during squatting. Nine participants were assessed when performing 2 × 5 traditional squats with a weight of 70% of the 1 repetition maximum and ballistic squats with a weight of 25 kg. Simultaneously, data was recorded from three linear position transducers (T-FORCE, Tendo Power and GymAware), an accelerometer based system (Myotest) and a 3D motion capture system (Vicon) as the Gold Standard. Correlations between the simple measurement devices and 3D motion capture of the mean and the maximal velocity of the barbell, as well as the time to maximal velocity, were calculated. The correlations during traditional squats were significant and very high (r = 0.932, 0.990, p squats and was less accurate. All the linear position transducers were able to assess squat performance, particularly during traditional squats and especially in terms of mean velocity and time to maximal velocity.

  8. On the Measurement of the Velocity of Light Emitted by an Ultrarelativistic Source

    Science.gov (United States)

    Kupryaev, N. V.

    2015-01-01

    By analytical calculations it has been shown that in papers on the measurement of the velocity of light published in 2011 in the journals Uspekhi Fizicheskikh Nauk [Physics-Uspekhi] and Pis'ma v ZhETF [JRTP Letters], in actual fact the velocity of a light pulse from a relativistic clot of electrons was not measured. All that was done was to compare the velocity of light emitted by an ultrarelativistic source with the velocity of light from a fixed source, i.e., both in the first and second variants (one independent quantity was compared with another), in essence, it was simply postulated. In the first variant a glass plate was used as the fixed light source, and in the second variants, a synchrotron pulse was used as the reference signal. The velocity of light was calculated using a calculated time based on the postulate of the special theory of relativity (STR) on the invariance of the velocity of light. This, of course, contradicts the Newton-Ritz hypothesis on ballistic addition of velocities, but at the present time this idea is not taken seriously. Practically none of the serious contemporary critics of STR, apart, of course, from amateurs, holds this point of view. The result cannot be considered as a direct experimental confirmation of the second postulate of Einstein's special theory of relativity, i.e., its main part, which speaks of the constancy of the velocity of light in all inertial reference frames, but only of that part which speaks of the independence of the velocity of light on motion of the source. Moreover, this same result stands as equal proof of the so-called theory of the luminiferous ether, which held sway up to the creation of the special theory of relativity and which has now been revived, i.e., it does not distinguish between these two theories. It is fundamentally impossible in principle to measure the velocity of light by the proposed method, it is only possible to postulate it.

  9. Visualization and PIV measurement of unsteady flow around a darrieus wind turbine in dynamic stall

    Energy Technology Data Exchange (ETDEWEB)

    Shibuya, Satoshi; Fujisawa, Nobuyuki; Takano, Tsuyoshi [Dept. of Mechanical and Production Engineering, Niigata Univ., Niigata (Japan)

    1999-07-01

    Flow around a Darrieus wind turbine in dynamic stall is studied by flow visualization and PIV (particle image velocimeter) measurement in a rotating frame of reference, which allows the successive observation of the dynamic stall over the blade. The qualitative features of the flow field in dynamic stall observed by the flow visualization, such as the formation and shedding of the stall vortices, are quantitatively reproduced in the instantaneous velocity distributions near the blade by using PIV. These results indicate that two pairs of stall vortices are generated from the blade during one rotation of the blade and that the size and the generating blade angle of the stall vortices are enlarged as the tip-speed ratio decreases. These stall vortices are produced by the in-flow motion from the outer surface to the inner surface through the trailing edge of the blade and the flow separation over the inner surface of the blade. (author)

  10. Measurements of the laminar burning velocity of hydrogen-air premixed flames

    Energy Technology Data Exchange (ETDEWEB)

    Pareja, Jhon; Burbano, Hugo J. [Science and Technology of Gases and Rational Use of Energy Group, Faculty of Engineering, University of Antioquia, Calle 67 N 53, 108 Bloque 20, 447 Medellin (Colombia); Ogami, Yasuhiro [Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan)

    2010-02-15

    Experimental and numerical studies on laminar burning velocities of hydrogen-air mixtures were performed at standard pressure and room temperature varying the equivalence ratio from 0.8 to 3.0. The flames were generated using a contoured slot-type nozzle burner (4 mm x 10 mm). Measurements of laminar burning velocity were conducted using particle tracking velocimetry (PTV) combined with Schlieren photography. This technique provides the information of instantaneous local burning velocities in the whole region of the flame front, and laminar burning velocities were determined using the mean value of local burning velocities in the region of non-stretch. Additionally, average laminar burning velocities were determined using the angle method and compared with the data obtained with the PTV method. Numerical calculations were also conducted using detailed reaction mechanisms and transport properties. The experimental results from the PTV method are in good agreement with the numerical results at every equivalence ratio of the range of study. Differences between the results obtained with the angle method and those with the PTV method are reasonably small when the effects of flame stretch and curvature are reduced by using a contoured slot-type nozzle. (author)

  11. The in situ permeable flow sensor: A device for measuring groundwater flow velocity

    International Nuclear Information System (INIS)

    Ballard, S.; Barker, G.T.; Nichols, R.L.

    1994-03-01

    A new technology called the In Situ Permeable Flow Sensor has been developed at Sandia National Laboratories. These sensors use a thermal perturbation technique to directly measure the direction and magnitude of the full three dimensional groundwater flow velocity vector in unconsolidated, saturated, porous media. The velocity measured is an average value characteristic of an approximately 1 cubic meter volume of the subsurface. During a test at the Savannah River Site in South Carolina, two flow sensors were deployed in a confined aquifer in close proximity to a well which was screened over the entire vertical extent of the aquifer and the well was pumped at four different pumping rates. In this situation horizontal flow which is radially directed toward the pumping well is expected. The flow sensors measured horizontal flow which was directed toward the pumping well, within the uncertainty in the measurements. The observed magnitude of the horizontal component of the flow velocity increased linearly with pumping rate, as predicted by theoretical considerations. The measured horizontal component of the flow velocity differed from the predicted flow velocity, which was calculated with the assumptions that the hydraulic properties of the aquifer were radially homogeneous and isotropic, by less than a factor of two. Drawdown data obtained from other wells near the pumping well during the pump test indicate that the hydraulic properties of the aquifer are probably not radially homogeneous but the effect of the inhomogeneity on the flow velocity field around the pumping well was not modeled because the degree and distribution of the inhomogeneity are unknown. Grain size analysis of core samples from wells in the area were used to estimate the vertical distribution of hydraulic conductivity

  12. Measurement of Aortic Pulse Wave Velocity With a Connected Bathroom Scale.

    Science.gov (United States)

    Campo, David; Khettab, Hakim; Yu, Roger; Genain, Nicolas; Edouard, Paul; Buard, Nadine; Boutouyrie, Pierre

    2017-09-01

    Measurement of arterial stiffness should be more available. Our aim was to show that aortic pulse wave velocity can be reliably measured with a bathroom scale combining the principles of ballistocardiography (BCG) and impedance plethysmography on a single foot. The calibration of the bathroom scale was conducted on a group of 106 individuals. The aortic pulse wave velocity was measured with the SphygmoCor in the supine position. Three consecutive measurements were then performed on the Withings scale in the standing position. This aorta-leg pulse transit time (alPTT) was then converted into a velocity with the additional input of the height of the person. Agreement between the SphygmoCor and the bathroom scale so calibrated is assessed on a separate group of 86 individuals, following the same protocol. The bias is 0.25 m·s-1 and the SE 1.39 m·s-1. This agreement with Sphygmocor is "acceptable" according to the ARTERY classification. The alPTT correlated well with cfPTT with (Spearman) R = 0.73 in pooled population (cal 0.79, val 0.66). The aorta-leg pulse wave velocity correlated with carotid-femoral pulse wave velocity with R = 0.76 (cal 0.80, val 0.70). Estimation of the aortic pulse wave velocity is feasible with a bathroom scale. Further investigations are needed to improve the repeatability of measurements and to test their accuracy in different populations and conditions. © The Author 2017. Published by Oxford University Press on behalf of American Journal of Hypertension.

  13. Runoff velocity behaviour on smooth pavement and paving blocks surfaces measured by a tilted plot

    Directory of Open Access Journals (Sweden)

    Sedyowati Laksni

    2017-06-01

    Full Text Available Paving blocks have been widely known as an alternative technology for reducing runoff discharge due to their infiltration performance and capability of retarding the flow. Surface configuration of the different paving blocks types and the openings area play important role in decreasing the runoff velocity. In this study, we investigated the surface runoff velocity on two types of paving blocks layers, and a smooth pavement as comparison. The paving blocks type were rectangular blocks, which have 3.2% openings ratio and hexagonal blocks, which have 6.5% openings ratio. We used a tilted plot covering area of 2 × 6 m, equipped by a rainfall simulator to accommodate the variation of surface slope and rainfall intensity. We measured the velocity by using modification of dye tracer and buoyancy method. The data were then tabulated and graphed based on the paving types and the surface slopes. Generally, the velocity-slope relationship has demonstrated that the increase in surface slope leads to the increase in velocity. In this study, the result showed that slope and rainfall intensity simultaneously influenced the velocity (F = 19.91 > Ftable = 5.14; P < 0.05. However, the findings of this study showed a weak relationship between the changes of surface slope and the changes of runoff velocity on the rectangular blocks (R2 = 0.38. The greater slope did not always invariably lead to the greater runoff velocity. It was likely that there was other predictor variable that was not identified before, and need to be further investigated.

  14. Elastic Wave Velocity Measurements on Mantle Peridotite at High Pressure and Temperature

    Science.gov (United States)

    Mistler, G. W.; Ishikawa, M.; Li, B.

    2002-12-01

    With the success of conducting ultrasonic measurements at high pressure and high temperature in large volume high pressure apparatus with in-situ measurement of the sample length by X-ray imaging, it is now possible to measure elastic wave velocities on aggregate samples with candidate compositions of the mantle to the conditions of the Earth's transition zone in the laboratory. These data can be directly compared with seismic data to distinguish the compositional models in debate. In this work, we carried out velocity measurements on natural peridotite KLB-1 at the conditions of the Earth's upper mantle. Fine powered sample of natural KLB-1 was used as starting material. Specimens for ultrasonic measurements were hot-pressed and equilibrated at various pressure and temperature conditions along geotherm up to the transition zone. The recovered samples were characterized with density measurement, X-ray diffraction and microprobe analysis. Bench top P and S wave velocities of KLB-1 sample sintered at 3-4 GPa and 1400 degree centigrade showed a very good agreement with the VRH average of pyrolite. High pressure and high temperature measurements was conducted up to 7 GPa and 800 degree centigrade using ultrasonic interferometric method in a DIA-type high pressure apparatus in conjunction with X-ray diffraction and X-ray imaging. The utilization of X-ray imaging technique provides direct measurements of sample lengths at high pressure and high temperature, ensuring a precise determination of velocities. The results of P and S wave velocities at high pressure and high temperature as well as their comparison with calculated pyrolite model will be presented.

  15. Comparison of Flight Measured, Predicted and Wind Tunnel Measured Winglet Characteristics on a KC-135 Aircraft

    Science.gov (United States)

    Dodson, R. O., Jr.

    1982-01-01

    One of the objectives of the KC-135 Winglet Flight Research and Demonstration Program was to obtain experimental flight test data to verify the theoretical and wind tunnel winglet aerodynamic performance prediction methods. Good agreement between analytic, wind tunnel and flight test performance was obtained when the known differences between the tests and analyses were accounted for. The flight test measured fuel mileage improvements for a 0.78 Mach number was 3.1 percent at 8 x 10(5) pounds W/delta and 5.5 percent at 1.05 x 10(6) pounds W/delta. Correcting the flight measured data for surface pressure differences between wind tunnel and flight resulted in a fuel mileage improvement of 4.4 percent at 8 x 10(5) pounds W/delta and 7.2 percent at 1.05 x 10(6) pounds W/delta. The performance improvement obtained was within the wind tunnel test data obtained from two different wind tunnel models. The buffet boundary data obtained for the baseline configuration was in good agreement with previous established data. Buffet data for the 15 deg cant/-4 deg incidence configuration showed a slight improvement, while the 15 deg cant/-2 deg incidence and 0 deg cant/-4 deg incidence data showed a slight deterioration.

  16. MR velocity mapping measurement of renal artery blood flow in patients with impaired kidney function

    DEFF Research Database (Denmark)

    Cortsen, M; Petersen, L.J.; Stahlberg, F

    1996-01-01

    Renal blood flow (RBF) was measured in 9 patients with chronic impaired kidney function using MR velocity mapping and compared to PAH clearance and 99mTc-DTPA scintigraphy. An image plane suitable for flow measurement perpendicular to the renal arteries was chosen from 2-dimensional MR angiography....... MR velocity mapping was performed in both renal arteries using an ECG-triggered gradient echo pulse sequence previously validated in normal volunteers. Effective renal plasma flow was calculated from the clearance rate of PAH during constant infusion and the split of renal function was evaluated...... by 99mTc-DTPA scintigraphy. A reduction of RBF was found, and there was a significant correlation between PAH clearance multiplied by 1/(1-hematocrit) and RBF determined by MR velocity mapping. Furthermore, a significant correlation between the distribution of renal function and the percent distribution...

  17. Two-phase velocity measurements around cylinders using particle image velocimetry

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, Y.A.; Philip, O.G.; Schmidl, W.D. [Texas A& M Univ., College Station, TX (United States)] [and others

    1995-09-01

    The particle Image Velocimetry flow measurement technique was used to study both single-phase flow and two-phase flow across a cylindrical rod inserted in a channel. First, a flow consisting of only a single-phase fluid was studied. The experiment consisted of running a laminar flow over four rods inserted in a channel. The water flow rate was 126 cm{sup 3}/s. Then a two-phase flow was studied. A mixture of water and small air bubbles was used. The water flow rate was 378 cm{sup 3}/s and the air flow rate was approximately 30 cm{sup 3}/s. The data are analyzed to obtain the velocity fields for both experiments. After interpretation of the velocity data, forces acting on a bubble entrained by the vortex were calculated successfully. The lift and drag coefficients were calculated using the velocity measurements and the force data.

  18. Complete methodology on generating realistic wind speed profiles based on measurements

    DEFF Research Database (Denmark)

    Gavriluta, Catalin; Spataru, Sergiu; Mosincat, Ioan

    2012-01-01

    , wind modelling for medium and large time scales is poorly treated in the present literature. This paper presents methods for generating realistic wind speed profiles based on real measurements. The wind speed profile is divided in a low- frequency component (describing long term variations...

  19. Comparison of Large Eddy Simulations of a convective boundary layer with wind LIDAR measurements

    DEFF Research Database (Denmark)

    Pedersen, Jesper Grønnegaard; Kelly, Mark C.; Gryning, Sven-Erik

    2012-01-01

    Vertical profiles of the horizontal wind speed and of the standard deviation of vertical wind speed from Large Eddy Simulations of a convective atmospheric boundary layer are compared to wind LIDAR measurements up to 1400 m. Fair agreement regarding both types of profiles is observed only when...

  20. European wind turbine testing procedure developments. Task 1: Measurement method to verify wind turbine performance characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Hunter, R.; Friis Pedersen, T.; Dunbabin, P.; Antoniou, I.; Frandsen, S.; Klug, H.; Albers, A.; Lee, W.K.

    2001-01-01

    There is currently significant standardisation work ongoing in the context of wind farm energy yield warranty assessment and wind turbine power performance testing. A standards maintenance team is revising the current IEC (EN) 61400-12 Ed 1 standard for wind turbine power performance testing. The standard is being divided into four documents. Two of them are drafted for evaluation and verification of complete wind farms and of individual wind turbines within wind farms. This document, and the project it describes, has been designed to help provide a solid technical foundation for this revised standard. The work was wide ranging and addressed 'grey' areas of knowledge, regarding existing methodologies or to carry out basic research in support of fundamentally new procedures. The work has given rise to recommendations in all areas of the work, including site calibration procedures, nacelle anemometry, multi-variate regression analysis and density normalisation. (au)

  1. Measurement of velocity field in pipe with classic twisted tape using matching refractive index technique

    Energy Technology Data Exchange (ETDEWEB)

    Song, Min Seop; Park, So Hyun; Kim, Eung Soo [Seoul National Univ., Seoul (Korea, Republic of)

    2014-10-15

    Many researchers conducted experiments and numerical simulations to measure or predict a Nusselt number or a friction factor in a pipe with a twisted tape while some other studies focused on the heat transfer performance enhancement using various twisted tape configurations. However, since the optical access to the inner space of a pipe with a twisted tape was limited, the detailed flow field data were not obtainable so far. Thus, researchers mainly relied on the numerical simulations to obtain the data of the flow field. In this study, a 3D printing technique was used to manufacture a transparent test section for optical access. And also, a noble refractive index matching technique was used to eliminate optical distortion. This two combined techniques enabled to measure the velocity profile with Particle Image Velocimetry (PIV). The measured velocity field data can be used either to understand the fundamental flow characteristics around a twisted tape or to validate turbulence models in Computational Fluid Dynamics (CFD). In this study, the flow field in the test-section was measured for various flow conditions and it was finally compared with numerically calculated data. Velocity fields in a pipe with a classic twisted tape was measured using a particle image velocimetry (PIV) system. To obtain undistorted particle images, a noble optical technique, refractive index matching, was used and it was proved that high-quality image can be obtained from this experimental equipment. The velocity data from the PIV was compared with the CFD simulations.

  2. Local velocity measurements in lead-bismuth and sodium flows using the ultrasound doppler velocimetry

    International Nuclear Information System (INIS)

    Eckert, S.; Gerbeth, G.

    2003-01-01

    We will present measurements of the velocity profiles in liquid sodium and eutectic lead-bismuth by means of the Ultrasonic Doppler Velocimetry (UDV). A sodium flow in a rectangular duct exposed to an external, transverse magnetic field has been examined. To demonstrate the capability of UDV the transformation of the well-known turbulent, piston-like profile to an M-shaped velocity profile for growing magnetic field strength was observed. The significance of artifacts such as caused by the existence of reflecting interfaces in the measuring domain will be discussed. In the sodium case, the measurements were performed through the channel wall. An integrated ultrasonic sensor with acoustic wave-guide has been developed to overcome the limitation of ultrasonic transducers to temperatures lower than 200 .deg. C. This sensor can presently be applied at maximum temperatures up to 800 .deg. C. Stable and robust measurements have been performed in various PbBi flows in our laboratory at FZR as well as at the THESYS loop of the KALLA laboratory of the ForschungsZentrum Karlsruhe (FZK). We will also present experimental results obtained in a PbBi bubbly flow at 250...300 .deg. C. Argon bubbles were injected through a single orifice in a cylindrical container filled with stagnant PbBi. Velocity profiles were measured in the bubble plume. Mean values of the liquid as well as the bubble velocity were extracted from the data and will be presented as function of the gas flow rate

  3. Measurement of velocity field in pipe with classic twisted tape using matching refractive index technique

    International Nuclear Information System (INIS)

    Song, Min Seop; Park, So Hyun; Kim, Eung Soo

    2014-01-01

    Many researchers conducted experiments and numerical simulations to measure or predict a Nusselt number or a friction factor in a pipe with a twisted tape while some other studies focused on the heat transfer performance enhancement using various twisted tape configurations. However, since the optical access to the inner space of a pipe with a twisted tape was limited, the detailed flow field data were not obtainable so far. Thus, researchers mainly relied on the numerical simulations to obtain the data of the flow field. In this study, a 3D printing technique was used to manufacture a transparent test section for optical access. And also, a noble refractive index matching technique was used to eliminate optical distortion. This two combined techniques enabled to measure the velocity profile with Particle Image Velocimetry (PIV). The measured velocity field data can be used either to understand the fundamental flow characteristics around a twisted tape or to validate turbulence models in Computational Fluid Dynamics (CFD). In this study, the flow field in the test-section was measured for various flow conditions and it was finally compared with numerically calculated data. Velocity fields in a pipe with a classic twisted tape was measured using a particle image velocimetry (PIV) system. To obtain undistorted particle images, a noble optical technique, refractive index matching, was used and it was proved that high-quality image can be obtained from this experimental equipment. The velocity data from the PIV was compared with the CFD simulations

  4. Bayesian Integrated Data Analysis of Fast-Ion Measurements by Velocity-Space Tomography

    DEFF Research Database (Denmark)

    Salewski, M.; Nocente, M.; Jacobsen, A.S.

    2018-01-01

    Bayesian integrated data analysis combines measurements from different diagnostics to jointly measure plasma parameters of interest such as temperatures, densities, and drift velocities. Integrated data analysis of fast-ion measurements has long been hampered by the complexity of the strongly non...... framework. The implementation for different types of diagnostics as well as the uncertainties are discussed, and we highlight the importance of integrated data analysis of all available detectors....

  5. Quantification of rain gauge measurement undercatch and wind speed correction

    Science.gov (United States)

    Pollock, Michael; Quinn, Paul; Dutton, Mark; Wilkinson, Mark

    2014-05-01

    Hydrological processes are adversely affected by systematic rain gauge inaccuracy due to wind induced undercatching. The implications of this are discussed and addressed. Despite evidence of the undercatch problem being cited in the past and the difficulty in solving such a complex problem; it has become an inconvenient truth to hydrologists that major inaccuracies in rainfall measurement exist. A two year long experiment using new equipment and improved data logging and telemetery techniques enriches this formative work to redress the wilful neglect with which accurate rainfall measurement has been treated in recent decades. Results from this work suggest that the annual systematic undercatch can be in the order of 20 percent in the UK. During specific periods (measured at high temporal resolution), this can rise to as high as 50 percent for a single wind impacted event. As one organisation, responsible for the environment in the UK, moves towards using fewer instruments (15 percent fewer in the next year), it is scarcely possible to overstate the importance in solving this problem. It had been hoped that new equipment, such as acoustic distrometer and weighing gauge technologies, would be able to reduce the magnitude of the bias. However, through data gathered in the 2 year experiment and through secondary sources from the 1970s and 1980s, it is demonstrated that this is not the case and that the same problems with undercatching remain now as they did then. We further postulate that wider, denser networks of inexpensive telemetered equipment are now possible but they must still address the undercatch issue. There is little merit in pointing out an age old problem if no solution is put forward to fix it. The aforementioned experiment has furnished new ideas and further work has been commissioned to address this problem. This will be achieved via the medium of a Knowledge Transfer Partnership between Newcastle University and an innovative equipment manufacturer

  6. Wind-stilling in the light of wind speed measurements: the Czech experience

    Czech Academy of Sciences Publication Activity Database

    Brázdil, Rudolf; Valík, A.; Zahradníček, Pavel; Řezníčková, Ladislava; Tolasz, R.; Možný, M.

    2018-01-01

    Roč. 74 (2018), s. 131-143 ISSN 0936-577X R&D Projects: GA MŠk(CZ) LO1415; GA ČR(CZ) GA15-11805S Institutional support: RVO:86652079 Keywords : universal anemograph * vaisala wind-speed sensors * wind speed * homogenisation * wind stilling * Czech Republic Subject RIV: DG - Athmosphere Sciences, Meteorology OBOR OECD: Meteorology and atmospheric sciences Impact factor: 1.578, year: 2016

  7. Rate of rotation measurement using back-EMFS associated with windings of a brushless DC motor

    Science.gov (United States)

    Howard, David E. (Inventor)

    2000-01-01

    A system and method are provided for measuring rate of rotation. A brushless DC motor is rotated and produces a back electromagnetic force (emf) on each winding thereof. Each winding's back-emf is integrated and multiplied by the back-emf associated with an adjacent winding. The multiplied outputs associated with each winding are combined to produce a directionally sensitive DC output proportional only to the rate of rotation of the motor's shaft.

  8. Griffon vulture mortality at wind farms in southern Spain: Distribution of fatalities and active mitigation measures

    OpenAIRE

    Lucas, Manuela de; Ferrer, Miguel; Bechard, Mark J.; Muñoz, Antonio R.

    2012-01-01

    Wind is increasingly being used as a renewable energy source around the world. Avian mortality is one of the negative impacts of wind energy and a new technique that reduces avian collision rates is necessary. Using the most frequently-killed species, the griffon vulture (Gyps fulvus), we studied its mortality at 13 wind farms in Tarifa, Cadiz, Spain, before (2006-2007) and after (2008-2009) when selective turbine stopping programs were implemented as a mitigation measure. Ten wind farms (tot...

  9. Inertial Navigation System/Doppler Velocity Log (INS/DVL Fusion with Partial DVL Measurements

    Directory of Open Access Journals (Sweden)

    Asaf Tal

    2017-02-01

    Full Text Available The Technion autonomous underwater vehicle (TAUV is an ongoing project aiming to develop and produce a small AUV to carry on research missions, including payload dropping, and to demonstrate acoustic communication. Its navigation system is based on an inertial navigation system (INS aided by a Doppler velocity log (DVL, magnetometer, and pressure sensor (PS. In many INSs, such as the one used in TAUV, only the velocity vector (provided by the DVL can be used for aiding the INS, i.e., enabling only a loosely coupled integration approach. In cases of partial DVL measurements, such as failure to maintain bottom lock, the DVL cannot estimate the vehicle velocity. Thus, in partial DVL situations no velocity data can be integrated into the TAUV INS, and as a result its navigation solution will drift in time. To circumvent that problem, we propose a DVL-based vehicle velocity solution using the measured partial raw data of the DVL and additional information, thereby deriving an extended loosely coupled (ELC approach. The implementation of the ELC approach requires only software modification. In addition, we present the TAUV six degrees of freedom (6DOF simulation that includes all functional subsystems. Using this simulation, the proposed approach is evaluated and the benefit of using it is shown.

  10. 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...

  11. Pollutant Plume Dispersion over Hypothetical Urban Areas based on Wind Tunnel Measurements

    Science.gov (United States)

    Mo, Ziwei; Liu, Chun-Ho

    2017-04-01

    Gaussian plume model is commonly adopted for pollutant concentration prediction in the atmospheric boundary layer (ABL). However, it has a number of limitations being applied to pollutant dispersion over complex land-surface morphology. In this study, the friction factor (f), as a measure of aerodynamic resistance induced by rough surfaces in the engineering community, was proposed to parameterize the vertical dispersion coefficient (σz) in the Gaussian model. A series of wind tunnel experiments were carried out to verify the mathematical hypothesis and to characterize plume dispersion as a function of surface roughness as well. Hypothetical urban areas, which were assembled in the form of idealized street canyons of different aspect (building-height-to-street-width) ratios (AR = 1/2, 1/4, 1/8 and 1/12), were fabricated by aligning identical square aluminum bars at different separation apart in cross flows. Pollutant emitted from a ground-level line source into the turbulent boundary layer (TBL) was simulated using water vapour generated by ultrasonic atomizer. The humidity and the velocity (mean and fluctuating components) were measured, respectively, by humidity sensors and hot-wire anemometry (HWA) with X-wire probes in streamwise and vertical directions. Wind tunnel results showed that the pollutant concentration exhibits the conventional Gaussian distribution, suggesting the feasibility of using water vapour as a passive scalar in wind tunnel experiments. The friction factor increased with decreasing aspect ratios (widening the building separation). It was peaked at AR = 1/8 and decreased thereafter. Besides, a positive correlation between σz/xn (x is the distance from the pollutant source) and f1/4 (correlation coefficient r2 = 0.61) was observed, formulating the basic parameterization of plume dispersion over urban areas.

  12. Measurement system of bubbly flow using ultrasonic velocity profile monitor and video data processing unit

    International Nuclear Information System (INIS)

    Aritomi, Masanori; Zhou, Shirong; Nakajima, Makoto; Takeda, Yasushi; Mori, Michitsugu; Yoshioka, Yuzuru.

    1996-01-01

    The authors have been developing a measurement system for bubbly flow in order to clarify its multi-dimensional flow characteristics and to offer a data base to validate numerical codes for multi-dimensional two-phase flow. In this paper, the measurement system combining an ultrasonic velocity profile monitor with a video data processing unit is proposed, which can measure simultaneously velocity profiles in both gas and liquid phases, a void fraction profile for bubbly flow in a channel, and an average bubble diameter and void fraction. Furthermore, the proposed measurement system is applied to measure flow characteristics of a bubbly countercurrent flow in a vertical rectangular channel to verify its capability. (author)

  13. Melting along the Hugoniot and solid phase transition for Sn via sound velocity measurements

    Science.gov (United States)

    Song, Ping; Cai, Ling-cang; Tao, Tian-jiong; Yuan, Shuai; Chen, Hong; Huang, Jin; Zhao, Xin-wen; Wang, Xue-jun

    2016-11-01

    It is very important to determine the phase boundaries for materials with complex crystalline phase structures to construct their corresponding multi-phase equation of state. By measuring the sound velocity of Sn with different porosities, different shock-induced melting pressures along the solid-liquid phase boundary could be obtained. The incipient shock-induced melting of porous Sn samples with two different porosities occurred at a pressure of about 49.1 GPa for a porosity of 1.01 and 45.6 GPa for a porosity of 1.02, based on measurements of the sound velocity. The incipient shock-induced melting pressure of solid Sn was revised to 58.1 GPa using supplemental measurements of the sound velocity. Trivially, pores in Sn decreased the shock-induced melting pressure. Based on the measured longitudinal sound velocity data, a refined solid phase transition and the Hugoniot temperature-pressure curve's trend are discussed. No bcc phase transition occurs along the Hugoniot for porous Sn; further investigation is required to understand the implications of this finding.

  14. Flow velocity measurement by using zero-crossing polarity cross correlation method

    International Nuclear Information System (INIS)

    Xu Chengji; Lu Jinming; Xia Hong

    1993-01-01

    Using the designed correlation metering system and a high accurate hot-wire anemometer as a calibration device, the experimental study of correlation method in a tunnel was carried out. The velocity measurement of gas flow by using zero-crossing polarity cross correlation method was realized and the experimental results has been analysed

  15. A simple measurement method of molecular relaxation in a gas by reconstructing acoustic velocity dispersion

    Science.gov (United States)

    Zhu, Ming; Liu, Tingting; Zhang, Xiangqun; Li, Caiyun

    2018-01-01

    Recently, a decomposition method of acoustic relaxation absorption spectra was used to capture the entire molecular multimode relaxation process of gas. In this method, the acoustic attenuation and phase velocity were measured jointly based on the relaxation absorption spectra. However, fast and accurate measurements of the acoustic attenuation remain challenging. In this paper, we present a method of capturing the molecular relaxation process by only measuring acoustic velocity, without the necessity of obtaining acoustic absorption. The method is based on the fact that the frequency-dependent velocity dispersion of a multi-relaxation process in a gas is the serial connection of the dispersions of interior single-relaxation processes. Thus, one can capture the relaxation times and relaxation strengths of N decomposed single-relaxation dispersions to reconstruct the entire multi-relaxation dispersion using the measurements of acoustic velocity at 2N  +  1 frequencies. The reconstructed dispersion spectra are in good agreement with experimental data for various gases and mixtures. The simulations also demonstrate the robustness of our reconstructive method.

  16. Planar measurements of velocity and concentration of turbulent mixing in a T-junction

    DEFF Research Database (Denmark)

    Ingvorsen, Kristian Mark; Meyer, Knud Erik; Nielsen, N. F.

    Turbulent mixing of two isothermal air streams in a T-junction of square ducts are investigated. Three dimensional velocity fields and turbulent kinetic energy are measured with stereoscopic Particle Image Velocimetry (PIV). The concentration field is obtained with a planar Mie scattering technique...

  17. Viscosity estimation utilizing flow velocity field measurements in a rotating magnetized plasma

    International Nuclear Information System (INIS)

    Yoshimura, Shinji; Tanaka, Masayoshi Y.

    2008-01-01

    The importance of viscosity in determining plasma flow structures has been widely recognized. In laboratory plasmas, however, viscosity measurements have been seldom performed so far. In this paper we present and discuss an estimation method of effective plasma kinematic viscosity utilizing flow velocity field measurements. Imposing steady and axisymmetric conditions, we derive the expression for radial flow velocity from the azimuthal component of the ion fluid equation. The expression contains kinematic viscosity, vorticity of azimuthal rotation and its derivative, collision frequency, azimuthal flow velocity and ion cyclotron frequency. Therefore all quantities except the viscosity are given provided that the flow field can be measured. We applied this method to a rotating magnetized argon plasma produced by the Hyper-I device. The flow velocity field measurements were carried out using a directional Langmuir probe installed in a tilting motor drive unit. The inward ion flow in radial direction, which is not driven in collisionless inviscid plasmas, was clearly observed. As a result, we found the anomalous viscosity, the value of which is two orders of magnitude larger than the classical one. (author)

  18. On measuring surface wave phase velocity from station–station cross-correlation of ambient signal

    DEFF Research Database (Denmark)

    Boschi, Lapo; Weemstra, Cornelis; Verbeke, Julie

    2012-01-01

    We apply two different algorithms to measure surface wave phase velocity, as a function of frequency, from seismic ambient noise recorded at pairs of stations from a large European network. The two methods are based on consistent theoretical formulations, but differ in the implementation: one met...

  19. Recovery of Stokes waves from velocity measurements on an axis of symmetry

    International Nuclear Information System (INIS)

    Matioc, Bogdan-Vasile

    2015-01-01

    We provide a new method to recover the profile of Stokes waves, and more generally of waves with smooth vorticity, from measurements of the horizontal velocity component on a vertical axis of symmetry of the wave surface. Although we consider periodic waves only, the extension to solitary waves is straightforward. (paper)

  20. Velocity flow field and water level measurements in shoaling and breaking water waves

    CSIR Research Space (South Africa)

    Mukaro, R

    2010-01-01

    Full Text Available In this paper we report on the laboratory investigations of breaking water waves. Measurements of the water levels and instantaneous fluid velocities were conducted in water waves breaking on a sloping beach within a glass flume. Instantaneous water...

  1. Velocity field measurements in an evaporating sessile droplet by means of micro-PIV technique

    Directory of Open Access Journals (Sweden)

    Yagodnitsyna Anna

    2016-01-01

    Full Text Available Velocity fields are measured in evaporating sessile droplets on two substrates with different contact angles and contact angle hysteresis using micro resolution particle image velocimetry technique. Different flow patterns are observed in different stages of droplet evaporation: a flow with vortices and a radial flow. Flow structure is found to be similar for droplets on different substrates.

  2. High Time-Resolved Kinetic Temperatures of Solar Wind Minor Ions Measured with SOHO/CELIAS/CTOF

    Science.gov (United States)

    Janitzek, N. P.; Berger, L.; Drews, C.; Wimmer-Schweingruber, R. F.

    2017-12-01

    Solar wind heavy ions with an atomic number Z > 2 are referred to as minor ions since they represent a fraction of less than one percent of all solar wind ions. They can be therefore regarded as test particles, only reacting to but not driving the dynamics of the solar wind plasma, which makes them a unique diagnostic tool for plasma wave phenomena both in the solar atmosphere and the extended heliosphere. In the past, several studies have investigated the kinetic temperatures of minor ions, but due to low counting statistics these studies are based on ion velocity distribution functions (VDFs) recorded over time periods of several hours. The Charge Time-Of-Flight (CTOF) mass spectrometer as part of the Charge, ELement and Isotope Analysis System (CELIAS) onboard the SOlar and Heliospheric Observatory (SOHO) provides solar wind heavy ion 1D radial VDFs with excellent charge state separation, an unprecedented cadence of 5 minutes and very high counting statistics, exceeding similar state-of-the-art instruments by a factor of ten. In our study, based on CTOF measurements at Langrangian point L1 between DOY 150 and DOY 220 in 1996, we investigate systematically the influence of the VDF time resolution on the derived kinetic temperatures for solar wind silicon and iron ions. The selected ion set spans a wide range of mass-per-charge from 3 amu/e heavy ions with ion-cyclotron waves.

  3. Measurements of Waves in a Wind-wave Tank Under Steady and Time-varying Wind Forcing.

    Science.gov (United States)

    Zavadsky, Andrey; Shemer, Lev

    2018-02-13

    This manuscript describes an experimental procedure that allows obtaining diverse quantitative information on temporal and spatial evolution of water waves excited by time-dependent and steady wind forcing. Capacitance-type wave gauge and Laser Slope Gauge (LSG) are used to measure instantaneous water surface elevation and two components of the instantaneous surface slope at a number of locations along the test section of a wind-wave facility. The computer-controlled blower provides airflow over the water in the tank whose rate can vary in time. In the present experiments, the wind speed in the test section initially increases quickly from rest to the set value. It is then kept constant for the prescribed duration; finally, the airflow is shut down. At the beginning of each experimental run, the water surface is calm and there is no wind. Operation of the blower is initiated simultaneously with the acquisition of data provided by all sensors by a computer; data acquisition continues until the waves in the tank fully decay. Multiple independent runs performed under identical forcing conditions allow determining statistically reliable ensemble-averaged characteristic parameters that quantitatively describe wind-waves' variation in time for the initial development stage as a function of fetch. The procedure also allows characterizing the spatial evolution of the wave field under steady wind forcing, as well as decay of waves in time, once the wind is shut down, as a function of fetch.

  4. An MPC approach to individual pitch control of wind turbines using uncertain LIDAR measurements

    DEFF Research Database (Denmark)

    Mirzaei, Mahmood; Soltani, Mohsen; Poulsen, Niels Kjølstad

    2013-01-01

    wind turbine in the full load region is considered. Model predictive control (MPC) is used to solve the problem. A new approach is proposed to simplify the optimization problem of MPC. We linearize the obtained nonlinear model for different operating points which are determined by the effective wind...... speed on the rotor disc and take the wind speed as a scheduling variable. The wind speed is measurable ahead of the turbine using LIDARs, therefore the scheduling variable is known for the entire prediction horizon. We consider uncertainty in the wind propagation, which is the traveling time of wind...... from the LIDAR measurement point to the rotor. An algorithm based on wind speed estimation and measurements from the LIDAR is devised to find an estimate of the delay and compensate for it before it is used in the controller. Comparisons between the MPC with error compensation, without error...

  5. Galileo, measurement of the velocity of light, and the reaction times.

    Science.gov (United States)

    Foschi, Renato; Leone, Matteo

    2009-01-01

    According to the commonly accepted view, Galileo Galilei devised in 1638 an experiment that seemed able to show that the velocity of light is finite. An analysis of archival material shows that two decades later members of the Florence scientific society Accademia del Cimento followed Galileo guidelines by actually attempting to measure the velocity of light and suggesting improvements. This analysis also reveals a fundamental difference between Galileo's and Florence academy's methodologies and that Galileo's experiment was, in some respects, a pioneering work affecting also the history of the psychology of perception.

  6. A 4-spot time-of-flight anemometer for small centrifugal compressor velocity measurements

    Science.gov (United States)

    Wernet, Mark P.; Skoch, Gary J.

    1992-01-01

    The application of laser anemometry techniques in turbomachinery facilities is a challenging dilemma requiring an anemometer system with special qualities. Here, we describe the use of a novel laser anemometry technique applied to a small 4.5 kg/s, 4:1 pressure ratio centrifugal compressor. Sample velocity profiles across the blade pitch are presented for a single location along the rotor. The results of the intra-blade passage velocity measurements will ultimately be used to verify CFD 3-D viscous code predictions.

  7. Compact, High Energy 2-micron Coherent Doppler Wind Lidar Development for NASA's Future 3-D Winds Measurement from Space

    Science.gov (United States)

    Singh, Upendra N.; Koch, Grady; Yu, Jirong; Petros, Mulugeta; Beyon, Jeffrey; Kavaya, Michael J.; Trieu, Bo; Chen, Songsheng; Bai, Yingxin; Petzar, paul; hide

    2010-01-01

    This paper presents an overview of 2-micron laser transmitter development at NASA Langley Research Center for coherent-detection lidar profiling of winds. The novel high-energy, 2-micron, Ho:Tm:LuLiF laser technology developed at NASA Langley was employed to study laser technology currently envisioned by NASA for future global coherent Doppler lidar winds measurement. The 250 mJ, 10 Hz laser was designed as an integral part of a compact lidar transceiver developed for future aircraft flight. Ground-based wind profiles made with this transceiver will be presented. NASA Langley is currently funded to build complete Doppler lidar systems using this transceiver for the DC-8 aircraft in autonomous operation. Recently, LaRC 2-micron coherent Doppler wind lidar system was selected to contribute to the NASA Science Mission Directorate (SMD) Earth Science Division (ESD) hurricane field experiment in 2010 titled Genesis and Rapid Intensification Processes (GRIP). The Doppler lidar system will measure vertical profiles of horizontal vector winds from the DC-8 aircraft using NASA Langley s existing 2-micron, pulsed, coherent detection, Doppler wind lidar system that is ready for DC-8 integration. The measurements will typically extend from the DC-8 to the earth s surface. They will be highly accurate in both wind magnitude and direction. Displays of the data will be provided in real time on the DC-8. The pulsed Doppler wind lidar of NASA Langley Research Center is much more powerful than past Doppler lidars. The operating range, accuracy, range resolution, and time resolution will be unprecedented. We expect the data to play a key role, combined with the other sensors, in improving understanding and predictive algorithms for hurricane strength and track. 1

  8. Damage preventing measures for wind turbines. Phase 1- Reliability data

    Energy Technology Data Exchange (ETDEWEB)

    Carlsson, Fredrik; Eriksson, Emil; Dahlberg, Magnus

    2010-08-15

    The state of existing reliability and failure data in the public sources has been investigated. The prime goal has been to evaluate the data's usefulness for developing damage preventing measures. Some publicly available databases exist, and the data has been presented in several papers in the literature. The results from the investigation can seem quite negative. Detailed data are lacking and the level of detailed reporting has even been decreasing in recent years. Information on the impact of load condition on failures, which is an important question, are lacking throughout in the statistics. Some components dominate the failure statistics. These are for example the gearboxes, where failures lead to long down times. Failures of the electrical system lead to considerably shorter down times but the failure rate is much higher. Severe rotor failures seem to be rare, but they occur and the consequences can be dramatic. Operators and insurance companies are demanding improved insight in damage collection, maintenance and overall damage preventing measures. Closer cooperation with these parties could be a fruitful way of gathering more useful data. Improvements for future databases are suggested. A structure for damage collection is proposed. Comparing experience of damage preventing measures from other industries, knowledge about the nature of the damage mechanism and current practice in the wind industry will be an important tool in the evaluation of different damage preventing measures. This will be done in the following phases of this project

  9. Measuring the Bed Load velocity in Laboratory flumes using ADCP and Digital Cameras

    Science.gov (United States)

    Conevski, Slaven; Guerrero, Massimo; Rennie, Colin; Bombardier, Josselin

    2017-04-01

    Measuring the transport rate and apparent velocity of the bedload is notoriously hard and there is not a certain technique that would obtain continues data. There are many empirical models, based on the estimation of the shear stress, but only few involve direct measurement of the bed load velocity. The bottom tracking (BT) mode of an acoustic Doppler current profiler (ADCP) has been used many times to estimate the apparent velocity of the bed load. Herein is the basic idea, to exploit the bias of the BT signal towards the bed load movement and to calibrate this signal with traditional measuring techniques. These measurements are quite scarce and seldom reliable since there are not taken in controlled conditions. So far, no clear confirmation has been conducted in laboratory-controlled conditions that would attest the assumptions made in the estimation of the apparent bed load velocity, nor in the calibration of the empirical equations. Therefore, this study explores several experiments under stationary conditions, where the signal of the ADCP BT mode is recorded and compared to the bed load motion recorded by digital camera videography. The experiments have been performed in the hydraulic laboratories of Ottawa and Bologna, using two different ADCPs and two different high resolution cameras. In total, more then 30 experiments were performed for different sediment mixtures and different hydraulic conditions. In general, a good match is documented between the apparent bed load velocity measured by the ADCP and the videography. The slight deviation in single experiments can be explained by gravel particles inhomogeneity, difficult in reproducing the same hydro-sedimentological conditions and the randomness of the backscattering strength.

  10. European wind turbine testing procedure developments. Task 1: Measurement method to verify wind turbine performance characteristics

    DEFF Research Database (Denmark)

    Hunter, R.; Friis Pedersen, Troels; Dunbabin, P.

    2001-01-01

    There is currently significant standardisation work ongoing in the context of wind farm energy yield warranty assessment and wind turbine power performance testing. A standards maintenance team is revising the current IEC (EN) 61400-12 Ed 1 standard forwind turbine power performance testing....... The standard is being divided into four documents. Two of them are drafted for evaluation and verification of complete wind farms and of individual wind turbines within wind farms. This document, and the project itdescribes, has been designed to help provide a solid technical foundation for this revised...... standard. The work was wide ranging and addressed 'grey' areas of knowledge, regarding existing methodologies or to carry out basic research in support offundamentally new procedures. The work has given rise to recommendations in all areas of the work, including site calibration procedures, nacelle...

  11. Point Measurements of Fermi Velocities by a Time-of-Flight Method

    DEFF Research Database (Denmark)

    Falk, David S.; Henningsen, J. O.; Skriver, Hans Lomholt

    1972-01-01

    The present paper describes in detail a new method of obtaining information about the Fermi velocity of electrons in metals, point by point, along certain contours on the Fermi surface. It is based on transmission of microwaves through thin metal slabs in the presence of a static magnetic field...... applied parallel to the surface. The electrons carry the signal across the slab and arrive at the second surface with a phase delay which is measured relative to a reference signal; the velocities are derived by analyzing the magnetic field dependence of the phase delay. For silver we have in this way...... obtained one component of the velocity along half the circumference of the centrally symmetric orbit for B→∥[100]. The results are in agreement with current models for the Fermi surface. For B→∥[011], the electrons involved are not moving in a symmetry plane of the Fermi surface. In such cases one cannot...

  12. Direct measurements of the velocity and thickness of ''explosively'' propagating buried molten layers in amorphous silicon

    International Nuclear Information System (INIS)

    Lowndes, D.H.; Jellison, G.E. Jr.; Pennycook, S.J.; Withrow, S.P.; Mashburn, D.N.

    1986-01-01

    Simultaneous infrared (1152 nm) and visible (633 nm) reflectivity measurements with nanosecond resolution were used to study the initial formation and subsequent motion of pulsed KrF laser-induced ''explosively'' propagating buried molten layers in ion implantation-amorphized silicon. The buried layer velocity decreases with depth below the surface, but increases with KrF laser energy density; a maximum velocity of about 14 m/s was observed, implying an undercooling-velocity relationship of approx. 14 K/(m/s). Z-contrast scanning transmission electron microscopy was used to form a direct chemical image of implanted Cu ions transported by the buried layer and showed that the final buried layer thickness was <15 nm

  13. PIV measurements of velocities and accelerations under breaking waves on a slope

    DEFF Research Database (Denmark)

    Vested, Malene Hovgaard; Carstensen, Stefan; Christensen, Erik Damgaard

    2017-01-01

    waves. In this study, we have investigated the wave kinematics under steep and breaking waves on a laboratory beach with a slope of 1/25. The velocity field was measured by use of Particle Image Velocimetry (PIV) at a sample rate of 96Hz. The high sample rate allowed for the accelerations...... to be determined directly from the sampled velocities. It was found that both velocities and accelerations differ from the ones predicted from common wave theories such as streamfunction theory. This was especially evident at the top part of the wave close to the surface. This was not surprising, since...... the breaking event is a highly non-linear process. The results presented here may facilitate computations of the impact force on offshore structures and furthermore be used for validation of CFD models while altogether shedding light on the mechanisms behind breaking waves....

  14. A comparison of Doppler lidar wind sensors for Earth-orbit global measurement applications

    Science.gov (United States)

    Menzies, Robert T.

    1985-01-01

    Now, there are four Doppler lidar configurations which are being promoted for the measurement of tropospheric winds: (1) the coherent CO2 Lidar, operating in the 9 micrometer region using a pulsed, atmospheric pressure CO2 gas discharge laser transmitter, and heterodyne detection; (2) the coherent Neodymium doped YAG or Glass Lidar, operating at 1.06 micrometers, using flashlamp or diode laser optical pumping of the solid state laser medium, and heterodyne detection; (3) the Neodymium doped YAG/Glass Lidar, operating at the doubled frequency (at 530 nm wavelength), again using flashlamp or diode laser pumping of the laser transmitter, and using a high resolution tandem Fabry-Perot filter and direct detection; and (4) the Raman shifted Xenon Chloride Lidar, operating at 350 nm wavelength, using a pulsed, atmospheric pressure XeCl gas discharge laser transmitter at 308 nm, Raman shifted in a high pressure hydrogen cell to 350 nm in order to avoid strong stratospheric ozone absorption, also using a high resolution tandem Fabry-Perot filter and direct detection. Comparisons of these four systems can include many factors and tradeoffs. The major portion of this comparison is devoted to efficiency. Efficiency comparisons are made by estimating the number of transmitted photons required for a single pulse wind velocity estimate of + or - 1 m/s accuracy in the middle troposphere, from an altitude of 800 km, which is assured to be reasonable for a polar orbiting platform.

  15. An Assessment of Wind Plant Complex Flows Using Advanced Doppler Radar Measurements

    Science.gov (United States)

    Gunter, W. S.; Schroeder, J.; Hirth, B.; Duncan, J.; Guynes, J.

    2015-12-01

    As installed wind energy capacity continues to steadily increase, the need for comprehensive measurements of wind plant complex flows to further reduce the cost of wind energy has been well advertised by the industry as a whole. Such measurements serve diverse perspectives including resource assessment, turbine inflow and power curve validation, wake and wind plant layout model verification, operations and maintenance, and the development of future advanced wind plant control schemes. While various measurement devices have been matured for wind energy applications (e.g. meteorological towers, LIDAR, SODAR), this presentation will focus on the use of advanced Doppler radar systems to observe the complex wind flows within and surrounding wind plants. Advanced Doppler radars can provide the combined advantage of a large analysis footprint (tens of square kilometers) with rapid data analysis updates (a few seconds to one minute) using both single- and dual-Doppler data collection methods. This presentation demonstrates the utility of measurements collected by the Texas Tech University Ka-band (TTUKa) radars to identify complex wind flows occurring within and nearby operational wind plants, and provide reliable forecasts of wind speeds and directions at given locations (i.e. turbine or instrumented tower sites) 45+ seconds in advance. Radar-derived wind maps reveal commonly observed features such as turbine wakes and turbine-to-turbine interaction, high momentum wind speed channels between turbine wakes, turbine array edge effects, transient boundary layer flow structures (such as wind streaks, frontal boundaries, etc.), and the impact of local terrain. Operational turbine or instrumented tower data are merged with the radar analysis to link the observed complex flow features to turbine and wind plant performance.

  16. Development of three-dimensional individual bubble-velocity measurement method by bubble tracking

    International Nuclear Information System (INIS)

    Kanai, Taizo; Furuya, Masahiro; Arai, Takahiro; Shirakawa, Kenetsu; Nishi, Yoshihisa

    2012-01-01

    A gas-liquid two-phase flow in a large diameter pipe exhibits a three-dimensional flow structure. Wire-Mesh Sensor (WMS) consists of a pair of parallel wire layers located at the cross section of a pipe. Both the parallel wires cross at 90o with a small gap and each intersection acts as an electrode. The WMS allows the measurement of the instantaneous two-dimensional void-fraction distribution over the cross-section of a pipe, based on the difference between the local instantaneous conductivity of the two-phase flow. Furthermore, the WMS can acquire a phasic-velocity on the basis of the time lag of void signals between two sets of WMS. Previously, the acquired phasic velocity was one-dimensional with time-averaged distributions. The authors propose a method to estimate the three-dimensional bubble-velocity individually WMS data. The bubble velocity is determined by the tracing method. In this tracing method, each bubble is separated from WMS signal, volume and center coordinates of the bubble is acquired. Two bubbles with near volume at two WMS are considered as the same bubble and bubble velocity is estimated from the displacement of the center coordinates of the two bubbles. The validity of this method is verified by a swirl flow. The proposed method can successfully visualize a swirl flow structure and the results of this method agree with the results of cross-correlation analysis. (author)

  17. Development of three-dimensional phasic-velocity distribution measurement in a large-diameter pipe

    International Nuclear Information System (INIS)

    Kanai, Taizo; Furuya, Masahiro; Arai, Takahiro; Shirakawa, Kenetsu

    2011-01-01

    A wire-mesh sensor (WMS) can acquire a void fraction distribution at a high temporal and spatial resolution and also estimate the velocity of a vertical rising flow by investigating the signal time-delay of the upstream WMS relative to downstream. Previously, one-dimensional velocity was estimated by using the same point of each WMS at a temporal resolution of 1.0 - 5.0 s. The authors propose to extend this time series analysis to estimate the multi-dimensional velocity profile via cross-correlation analysis between a point of upstream WMS and multiple points downstream. Bubbles behave in various ways according to size, which is used to classify them into certain groups via wavelet analysis before cross-correlation analysis. This method was verified by air-water straight and swirl flows within a large-diameter vertical pipe. The results revealed that for the rising straight and swirl flows, large scale bubbles tend to move to the center, while the small bubble is pushed to the outside or sucked into the space where the large bubbles existed. Moreover, it is found that this method can estimate the rotational component of velocity of the swirl flow as well as measuring the multi-dimensional velocity vector at high temporal resolutions of 0.2s. (author)

  18. The spatial filtering method for solid particle velocity measurement based on an electrostatic sensor

    International Nuclear Information System (INIS)

    Xu, Chuanlong; Tang, Guanghua; Zhou, Bin; Wang, Shimin

    2009-01-01

    The spatial filtering method for particle velocity measurement has the advantages of simplicity of the measurement system and convenience of data processing. In this paper, the relationship between solid particles mean velocity in a pneumatic pipeline and the power spectrum of the output signal of an electrostatic sensor was mathematically modeled. The effects of the length of the sensor, the thickness of the dielectric pipe and its length on the spatial filtering characteristics of the sensor were also investigated using the finite element method. As for the roughness of and the difficult determination of the peak frequency f max of the power spectrum characteristics of the output signal of the sensor, a wavelet analysis based filtering method was applied to smooth the curve, which can accurately determine the peak frequency f max . Finally, experiments were performed on a pilot dense phase pneumatic conveying rig at high pressure to test the performance of the velocity measurement system. The experimental results show that the system repeatability is within ±4% over a gas superficial velocity range of 8.63–18.62 m s −1 for a particle concentration range of 0.067–0.130 m 3 m −3

  19. Measurement of the near-wall velocity profile for a nanofluid flow inside a microchannel

    Science.gov (United States)

    Kanjirakat, Anoop; Sadr, Reza

    2015-11-01

    Hydrodynamics and anomalous heat transfer enhancements have been reported in the past for colloidal suspensions of nano-sized particles dispersed in a fluid (nanofluids). However, such augmentations may manifest itself by study of fluid flow characteristics near in the wall region. Present experimental study reports near-wall velocity profile for nanofluids (silicon dioxide nanoparticles in water) measured inside a microchannel. An objective-based nano-Particle Image Velocimetry (nPIV) technique is used to measure fluid velocity within three visible depths, O(100nm), from the wall. The near-wall fluid velocity profile is estimated after implementing the required corrections for optical properties and effects caused by hindered Brownian motion, wall-particle interactions, and non-uniform exponential illumination on the measurement technique. The fluid velocities of nanofluids at each of the three visible depths are observed to be higher than that of the base fluid resulting in a higher shear rate in this region. The relative increase in shear rates for nanofluids is believed to be the result of the near-wall shear-induced particle migration along with the Brownian motion of the nanoparticles. This research is funded by NPRP grant # 08-574-2-239 from the Qatar National Research Fund (a member of Qatar Foundation).

  20. Continuous Sound Velocity Measurements along the Shock Hugoniot Curve of Quartz

    Science.gov (United States)

    Li, Mu; Zhang, Shuai; Zhang, Hongping; Zhang, Gongmu; Wang, Feng; Zhao, Jianheng; Sun, Chengwei; Jeanloz, Raymond

    2018-05-01

    We report continuous measurements of the sound velocity along the principal Hugoniot curve of α quartz between 0.25 and 1.45 TPa, as determined from lateral release waves intersecting the shock front as a function of time in decaying-shock experiments. The measured sound velocities are lower than predicted by prior models, based on the properties of stishovite at densities below ˜7 g /cm3 , but agree with density functional theory molecular dynamics calculations and an empirical wide-regime equation of state presented here. The Grüneisen parameter calculated from the sound velocity decreases from γ ˜1 .3 at 0.25 TPa to 0.66 at 1.45 TPa. In combination with evidence for increased (configurational) specific heat and decreased bulk modulus, the values of γ suggest a high thermal expansion coefficient at ˜0. 25 - 0 .65 TPa , where SiO2 is thought to be a bonded liquid. From our measurements, dissociation of the molecular bonds persists to ˜0. 65 - 1 .0 TPa , consistent with estimates by other methods. At higher densities, the sound velocity is close to predictions from previous models, and the Grüneisen parameter approaches the ideal gas value.