WorldWideScience

Sample records for anemometers

  1. Compact rotating cup anemometer

    Science.gov (United States)

    Wellman, J. B.

    1968-01-01

    Compact, collapsible rotating cup anemometer is used in remote locations where portability and durability are factors in the choice of equipment. This lightweight instrument has a low wind-velocity threshold, is capable of withstanding large mechanical shocks while in its stowed configuration, and has fast response to wind fluctuations.

  2. The perennial cup anemometer

    Science.gov (United States)

    Kristensen, L.

    1999-01-01

    A short version of the history of the cup anemometer precedes a more technical discussion of the special features of this instrument. These include its extremely linear calibration and the non-linearity of its response to wind speed changes. A simple conceptual model by Schrenk is used to demonstrate this and to explain why the cup anemometer is able to start from a zero rotation rate at zero wind to one corresponding to a sudden change in the ambient wind speed to a finite value. The same model is used to show that the cup anemometer should be characterized by a distance constant rather than by a time constant. The bias in the measured mean wind speed due to the random variations in the three velocity components is discussed in terms of standard, semiquantitative turbulence models, and the main thesis is that this bias is overwhelmingly dominated by the fluctuations of the lateral wind velocity component, i.e. the wind component perpendicular to the mean wind direction, and not, as is often assumed, by the longitudinal wind velocity component. It is shown theoretically and tested experimentally that the bias due to lateral wind velocity fluctuations can be significantly reduced by means of a special data processing of the simultaneous signals from a cup anemometer and a wind vane. This means that, with care, the overall overspeeding can be reduced to less than 1%.

  3. A Martian acoustic anemometer.

    Science.gov (United States)

    Banfield, Don; Schindel, David W; Tarr, Steve; Dissly, Richard W

    2016-08-01

    An acoustic anemometer for use on Mars has been developed. To understand the processes that control the interaction between surface and atmosphere on Mars, not only the mean winds, but also the turbulent boundary layer, the fluxes of momentum, heat and molecular constituents between surface and atmosphere must be measured. Terrestrially this is done with acoustic anemometers, but the low density atmosphere on Mars makes it challenging to adapt such an instrument for use on Mars. This has been achieved using capacitive transducers and pulse compression, and was successfully demonstrated on a stratospheric balloon (simulating the Martian environment) and in a dedicated Mars Wind Tunnel facility. This instrument achieves a measurement accuracy of ∼5 cm/s with an update rate of >20 Hz under Martian conditions.

  4. Cup Anemometer Overspeeding

    DEFF Research Database (Denmark)

    Busch, N. E.; Kristensen, Leif

    1976-01-01

    Statistical considerations are applied to a general equation of motion for cup anemometers in a turbulent wind. It is shown that the relative overspeeding ΔS/S can be expressed as ΔS/S = Ih2 · Js(l0/Λs) + cIw2, where Is and Iw are the horizontal and the vertical turbulence intensifies, respectively....... The function Js depends on the shape of the spectrum of horizontal turbulent energy, l0 is the distance constant for the anemometer, and Λs is a characteristic length scale of the horizontal turbulence. The constant c is of order unity. If Λs is suitably chosen as the scale of the energy-containing eddies...

  5. Field calibration of cup anemometers

    DEFF Research Database (Denmark)

    Schmidt Paulsen, Uwe; Mortensen, Niels Gylling; Hansen, Jens Carsten

    2007-01-01

    A field calibration method and results are described along with the experience gained with the method. The cup anemometers to be calibrated are mounted in a row on a 10-m high rig and calibrated in the free wind against a reference cup anemometer. The method has been reported [1] to improve...... the statistical bias on the data relative to calibrations carried out in a wind tunnel. The methodology is sufficiently accurate for calibration of cup anemometers used for wind resource assessments and provides a simple, reliable and cost-effective solution to cup anemometer calibration, especially suited...

  6. Thermal transient anemometer

    Science.gov (United States)

    Bailey, James L.; Vresk, Josip

    1989-01-01

    A thermal transient anemometer having a thermocouple probe which is utilized to measure the change in temperature over a period of time to provide a measure of fluid flow velocity. The thermocouple probe is located in the fluid flow path and pulsed to heat or cool the probe. The cooling of the heated probe or the heating of the cooled probe from the fluid flow over a period of time is measured to determine the fluid flow velocity. The probe is desired to be locally heated near the tip to increase the efficiency of devices incorporating the probe.

  7. Field calibration of cup anemometers

    DEFF Research Database (Denmark)

    Kristensen, L.; Jensen, G.; Hansen, A.

    2001-01-01

    An outdoor calibration facility for cup anemometers, where the signals from 10 anemometers of which at least one is a reference can be can be recorded simultaneously, has been established. The results are discussed with special emphasis on the statisticalsignificance of the calibration expressions....... It is concluded that the method has the advantage that many anemometers can be calibrated accurately with a minimum of work and cost. The obvious disadvantage is that the calibration of a set of anemometersmay take more than one month in order to have wind speeds covering a sufficiently large magnitude range...

  8. Calibration Fixture For Anemometer Probes

    Science.gov (United States)

    Lewis, Charles R.; Nagel, Robert T.

    1993-01-01

    Fixture facilitates calibration of three-dimensional sideflow thermal anemometer probes. With fixture, probe oriented at number of angles throughout its design range. Readings calibrated as function of orientation in airflow. Calibration repeatable and verifiable.

  9. Can A Cup Anemometer `Underspeed'?

    Science.gov (United States)

    Kristensen, L.

    An analysis of cup-anemometer dynamics has been carried out inorder to determine whether the mean-wind velocity can have anegative bias. This would be contrary to the general belief thatcup anemometers always overspeed. Compared to prior analyses, theeffect of a possible nonlinearity of the calibration function isincluded. The conclusion is that neither longitudinal nor lateralvelocity fluctuations can contribute significantly to a negativebias. However, if a cup anemometer has an angular response thatfalls below the ideal cosine response, there will, as demonstratedin the concluding discussion, be a negative contribution from thevertical velocity fluctuations to the total bias, and thiscontribution may even outbalance the positive contributions fromthe longitudinal velocity fluctuations. Concrete evidence of suchexotic cup anemometer behaviour has not been reported in theliterature.

  10. Field calibration of cup anemometers

    Energy Technology Data Exchange (ETDEWEB)

    Kristensen, L.; Jensen, G.; Hansen, A.; Kirkegaard, P.

    2001-01-01

    An outdoor calibration facility for cup anemometers, where the signals from 10 anemometers of which at least one is a reference can be recorded simultaneously, has been established. The results are discussed with special emphasis on the statistical significance of the calibration expressions. It is concluded that the method has the advantage that many anemometers can be calibrated accurately with a minimum of work and cost. The obvious disadvantage is that the calibration of a set of anemometers may take more than one month in order to have wind speeds covering a sufficiently large magnitude range in a wind direction sector where we can be sure that the instruments are exposed to identical, simultaneous wind flows. Another main conclusion is that statistical uncertainty must be carefully evaluated since the individual 10 minute wind-speed averages are not statistically independent. (au)

  11. Anomaly detection on cup anemometers

    Science.gov (United States)

    Vega, Enrique; Pindado, Santiago; Martínez, Alejandro; Meseguer, Encarnación; García, Luis

    2014-12-01

    The performances of two rotor-damaged commercial anemometers (Vector Instruments A100 LK) were studied. The calibration results (i.e. the transfer function) were very linear, the aerodynamic behavior being more efficient than the one shown by both anemometers equipped with undamaged rotors. No detection of the anomaly (the rotors’ damage) was possible based on the calibration results. However, the Fourier analysis clearly revealed this anomaly.

  12. On Cup Anemometer Rotor Aerodynamics

    OpenAIRE

    Santiago Pindado; Sergio Avila-Sanchez; Javier Pérez

    2012-01-01

    The influence of anemometer rotor shape parameters, such as the cups’ front area or their center rotation radius on the anemometer’s performance was analyzed. This analysis was based on calibrations performed on two different anemometers (one based on magnet system output signal, and the other one based on an opto-electronic system output signal), tested with 21 different rotors. The results were compared to the ones resulting from classical analytical models. The results clearly showed a lin...

  13. Plasma Anemometer Measurements and Optimization

    Science.gov (United States)

    Marshall, Curtis; Matlis, Eric; Corke, Thomas; Gogineni, Sivaram

    2013-11-01

    Velocity measurements using a constant-current plasma anemometer were performed in a Mach 0.4 jet in order to further optimize the anemometer design. The plasma anemometer uses an AC glow discharge (plasma) formed in the air gap between two protruding low profile electrodes as the flow sensing element. The output from the anemometer is an amplitude modulated version of the AC voltage input that contains information about the mean fluctuating velocity components. Experiments were performed to investigate the effect of the electrode gap, AC current, and AC frequency on the mean and fluctuating velocity sensitivity and repeatability of the sensor. This involved mean velocity calibrations from 0 to 140 m/s and mean and fluctuating velocity profiles through the shear layer of the jet. Measurements with a constant temperature hot-wire anemometer were used for reference. The results showed an improvement in performance with increasing AC frequency that was attributed a more stable glow discharge. The agreement with the hot-wire were good, with the advantage of the plasma anemometer being its 100-times higher frequency response. Supported by Air Force SBIR Phase II FA8650-11-C-2199.

  14. A satellite anemometer

    Science.gov (United States)

    Hanson, W. B.; Heelis, R. A.

    1995-01-01

    This report describes the design, development, and testing of components of a satellite anemometer, an instrument for measuring neutral winds in the upper atmosphere from a satellite platform. The device, which uses four nearly identical pressure sensors, measures the angle of arrival of the bulk neutral flow in the satellite frame of reference. It could also be used in a feedback loop to control spacecraft attitude with respect to the ram velocity direction. We have now developed miniaturized ionization pressure gauges that will work well from the slip flow region near 115 km up to the base of the exosphere, which covers the entire altitude range currently being considered for Tether. Laboratory tests have demonstrated a very linear response to changes in ram angle out to +/- 20 deg. (transverse wind component of 2.7 km s(exp -1)) from the ram, and a monotonic response to out beyond 45 deg. Pitch (vertical wind) and yaw (horizontal wind) can be sampled simultaneously and meaningfully up to 10 Hz. Angular sensitivity of 30 arc seconds (approximately 1 ms(exp -1) is readily attainable, but absolute accuracy for winds will be approximately 1 deg (130 m/s) unless independent attitude knowledge is available. The critical elements of the design have all been tested in the laboratory.

  15. Concept of porous wire anemometer

    Energy Technology Data Exchange (ETDEWEB)

    Afgan, N.H.; Pereira, J.C. [Inst. Superior Tecnico, Lisbon (Portugal); Leontiev, A.I.; Puzach, S.V. [Moscow Technical Univ. (Russian Federation)

    1997-05-01

    The paper presents a new scheme of the anemometer sensing element for the gas mean and fluctuation velocity measurement. The sensing element is a porous tube with gas suction through porous tube wall. The outside surface of the porous tube is at the gas temperature. The analysis, based on the heat balance at steady and unsteady state is performed in order to define the sensitivity and time constant of the porous sensing element. Two cases are considered, namely, the constant current and constant temperature anemometer. Comparison is made with the solid wire anemometer and shown that the proposed porous sensing element can have sensitivity four times higher than the standard hot wire anemometer with the same geometrical dimensions. With the respective selection of the physical properties of the sensing element, it could be possible to obtain higher frequency range of the measurement. Particular attention is devoted to the low gas velocity measurement. It is recognized that the minimum gas velocity to be measured with the solid hot wire anemometer is determined by the local heat transfer coefficient. For the low gas velocity, it was proved that the minimum is around .20 cm/sec. The proposed concept of the sensing element can be used for the very low velocity measurement due to the higher sensitivity obtained by the porous sensing element.

  16. On cup anemometer rotor aerodynamics.

    Science.gov (United States)

    Pindado, Santiago; Pérez, Javier; Avila-Sanchez, Sergio

    2012-01-01

    The influence of anemometer rotor shape parameters, such as the cups' front area or their center rotation radius on the anemometer's performance was analyzed. This analysis was based on calibrations performed on two different anemometers (one based on magnet system output signal, and the other one based on an opto-electronic system output signal), tested with 21 different rotors. The results were compared to the ones resulting from classical analytical models. The results clearly showed a linear dependency of both calibration constants, the slope and the offset, on the cups' center rotation radius, the influence of the front area of the cups also being observed. The analytical model of Kondo et al. was proved to be accurate if it is based on precise data related to the aerodynamic behavior of a rotor's cup.

  17. 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…

  18. Microsensor Hot-Film Anemometer

    Science.gov (United States)

    Mcginley, Catherine B.; Stephens, Ralph; Hopson, Purnell; Bartlett, James E.; Sheplak, Mark; Spina, Eric F.

    1995-01-01

    Improved hot-film anemometer developed for making high-bandwidth turbulence measurements in moderate-enthalpy supersonic and hypersonic flows (e.g., NASP inlets and control surfaces, HSCT jet exhaust). Features include low thermal inertia, ruggedness, and reduced perturbation of flow.

  19. On Cup Anemometer Rotor Aerodynamics

    Directory of Open Access Journals (Sweden)

    Santiago Pindado

    2012-05-01

    Full Text Available The influence of anemometer rotor shape parameters, such as the cups’ front area or their center rotation radius on the anemometer’s performance was analyzed. This analysis was based on calibrations performed on two different anemometers (one based on magnet system output signal, and the other one based on an opto-electronic system output signal, tested with 21 different rotors. The results were compared to the ones resulting from classical analytical models. The results clearly showed a linear dependency of both calibration constants, the slope and the offset, on the cups’ center rotation radius, the influence of the front area of the cups also being observed. The analytical model of Kondo et al. was proved to be accurate if it is based on precise data related to the aerodynamic behavior of a rotor’s cup.

  20. Development of Low Wind Speed Anemometer

    Directory of Open Access Journals (Sweden)

    Tan Wee Choon

    2012-01-01

    Full Text Available Anemometer is a measuring device used to measure the wind speed of an area. Before design or installing a wind turbine, it is important to determine the average wind speed of that particular area throughout the year. But it is illogically to purchase anemometer to measure the wind velocity for a year period. The purpose of this project is to design and fabricate a small scale of anemometer which will able to give the wind velocity with an acceptable range of uncertainty. The fabrication of the anemometer is developed using design methodology and simulation to obtain the optimized design. The designed anemometer has the mean absolute percentage error (MAPE of 3.23 % when compared with Dwyer series 471 thermo-anemometer.

  1. Some developments on cup anemometer aerodynamics

    OpenAIRE

    Pindado Carrion, Santiago; Cubas Cano, Javier

    2014-01-01

    In the present study the geometry of cups is experimentally studied through anemometer performance. This performance is analyzed in two different ways. On the one hand the anemometer transfer function between cases is compared. On the other hand the stationary rotation speed is decomposed into constant and harmonic terms, the comparison being established between the last ones. Results indicate that some cup shapes can improve the uniformity of anemometer rotation, this fact being important to...

  2. Distance constant of the Risoe cup anemometer

    Energy Technology Data Exchange (ETDEWEB)

    Kristensen, L.; Frost Hansen, O.

    2002-04-01

    The theory for cup-anemometer dynamics is presented in some detail and two methods of obtaining the distance constant . are discussed. The first method is based on wind tunnel measurements: with a constant wind speed the cup anemometer is released from a locked position of the rotor and the increasing rotation rate recorded. It is concluded that the rapid increase in rotation rate makes the method very inaccurate. The second method consists of an analysis of turbulent, atmospheric of wind speed as measured by the cup anemometer and a fast-responding sonic anemometer with a spatial eddy resolution which is significantly better than that which can be obtained by a cup anemometer. The ratio between the measured power spectra of the horizontal wind speed by the two instruments contains the necessary information for determining the response characteristics of the cup anemometer and thereby .. The conditions for this last method to be accurate are discussed. Field measurements are used to demonstrate how . is determined the Riso cup anemometer, model P2546.

  3. Sphere anemometer - a faster alternative solution to cup anemometry

    Science.gov (United States)

    Hölling, M.; Schulte, B.; Barth, S.; Peinke, J.

    2007-07-01

    We present an anemometer technique characterized by an instrument in a sealed enclosure without moving parts. Measurements taken with our improved sphere anemometer in comparison to cup anemometer and hot-wire anemometer data subjected to wind gusts are discussed. The hot-wire anemometer serves as a reference with high temporal and spacial resolution. A manually driven "gust generator" produced gusts at low frequencies of about 1Hz. All measurements were carried out in the wind tunnel at the University of Oldenburg.

  4. ACCUWIND - Methods for classification of cup anemometers

    DEFF Research Database (Denmark)

    Dahlberg, J.-Å.; Friis Pedersen, Troels; Busche, P.

    2006-01-01

    Errors associated with the measurement of wind speed are the major sources of uncertainties in power performance testing of wind turbines. Field comparisons of well-calibrated anemometers show significant and not acceptable difference. The EuropeanCLASSCUP project posed the objectives to quantify...... the errors associated with the use of cup anemometers, and to develop a classification system for quantification of systematic errors of cup anemometers. This classification system has now been implementedin the IEC 61400-12-1 standard on power performance measurements in annex I and J. The classification...... of cup anemometers requires general external climatic operational ranges to be applied for the analysis of systematic errors. A Class A categoryclassification is connected to reasonably flat sites, and another Class B category is connected to complex terrain, General classification indices are the result...

  5. New method to calibrate a spinner anemometer

    DEFF Research Database (Denmark)

    Demurtas, Giorgio; Friis Pedersen, Troels

    2014-01-01

    The spinner anemometer is a wind sensor, based on three one dimensional sonic sensor probes, mounted on the wind turbine spinner, and an algorithm to convert the wind speeds measured by the three sonic sensors to horizontal wind speed, yaw misalignment and flow inclination angle. The conversion...... to be stopped during calibration in order for the rotor induction not to influence on the calibration, so that the spinner anemometer measures ”free” wind values in stopped condition. The calibration of flow angle measurements is made by calibration of the ratio of the two algorithm constants k2=k1 = k......_. The calibration of k_ is made by relating the spinner anemometer yaw misalignment measurements to the yaw position when yawing the wind turbine in and out of the wind several times. The calibration of the constant k1 is made by comparing the spinner anemometer wind speed measurement with a free metmast or lidar...

  6. Frequency Responses Of Hot-Wire Anemometers

    Science.gov (United States)

    Watmuff, Jonathan H.

    1992-01-01

    Report describes theoretical study of frequency response of constant-temperature hot-wire anemometer, with view toward increasing frequency response while maintaining stable operation in supersonic flow. Effects of various circuit parameters discussed.

  7. ACCUWIND - Methods for classification of cup anemometers

    Energy Technology Data Exchange (ETDEWEB)

    Dahlberg, J.Aa.; Friis Pedersen, T.; Busche, P.

    2006-05-15

    Errors associated with the measurement of wind speed are the major sources of uncertainties in power performance testing of wind turbines. Field comparisons of well-calibrated anemometers show significant and not acceptable difference. The European CLASSCUP project posed the objectives to quantify the errors associated with the use of cup anemometers, and to develop a classification system for quantification of systematic errors of cup anemometers. This classification system has now been implemented in the IEC 61400-12-1 standard on power performance measurements in annex I and J. The classification of cup anemometers requires general external climatic operational ranges to be applied for the analysis of systematic errors. A Class A category classification is connected to reasonably flat sites, and another Class B category is connected to complex terrain, General classification indices are the result of assessment of systematic deviations. The present report focuses on methods that can be applied for assessment of such systematic deviations. A new alternative method for torque coefficient measurements at inclined flow have been developed, which have then been applied and compared to the existing methods developed in the CLASSCUP project and earlier. A number of approaches including the use of two cup anemometer models, two methods of torque coefficient measurement, two angular response measurements, and inclusion and exclusion of influence of friction have been implemented in the classification process in order to assess the robustness of methods. The results of the analysis are presented as classification indices, which are compared and discussed. (au)

  8. Optimization of Wind Turbine Operation by Use of Spinner Anemometer

    DEFF Research Database (Denmark)

    Friis Pedersen, Troels; Sørensen, Niels N.; Vita, Luca

    A prototype spinner anemometer was developed from a standard scientific sonic anemometer with specially designed 1D sonic sensors. A model spinner anemometer was tested in wind tunnel with two sensor head configurations. The tests showed that the sonic sensors responded with a high influence factor...... on yaw errors, and that the sensors responded with sinusoidal behaviour to rotation of the spinner. The tests also revealed a significant "sensor head flow distortion effect" from the classic sensor heads. A full CFD analysis of the model spinner anemometer was made. The results showed...... and increases the amplitude with a sine to the flow angle. The relation can be used in a conversion algorithm for the spinner anemometer. Field measurements were made with the model spinner anemometer. The spinner anemometer measurements were compared to measurements from a standard 3D sonic anemometer...

  9. Industry guidelines for the calibration of maximum anemometers

    Energy Technology Data Exchange (ETDEWEB)

    Bailey, B.H. [AWS Scientific, Inc., Albany, NY (United States)

    1996-12-31

    The purpose of this paper is to report on a framework of guidelines for the calibration of the Maximum Type 40 anemometer. This anemometer model is the wind speed sensor of choice in the majority of wind resource assessment programs in the U.S. These guidelines were established by the Utility Wind Resource Assessment Program. In addition to providing guidelines for anemometers, the appropriate use of non-calibrated anemometers is also discussed. 14 refs., 1 tab.

  10. Flow distortion on boom mounted cup anemometers

    DEFF Research Database (Denmark)

    Lindelöw, Per Jonas Petter; Friis Pedersen, Troels; Gottschall, Julia

    In this report we investigate on wind direction dependent errors in the measurement of the horizontal wind speed by boom mounted cup anemometers. The boom mounting on the studied lattice tower is performed according to IEC standard design rules, yet, larger deviations than predicted by flow models...... are observed. The errors on the measurements are likely caused by an underestimation of the flow distortions around the tower. In this paper an experimental method for deriving a correction formula and an in-field calibration is suggested. The method is based on measurements with two cup anemometers mounted...... in the measurement of wind turbine power performance, wind resource assessment and for providing purposeful in-field comparisons between different sensors, e.g. lidar anemometers. With the proposed method, direction dependent errors can be extracted and the mast flow distortion effect on the wind measurements...

  11. Comparison of Prevalent Types of Sonic Anemometers

    Science.gov (United States)

    Mauder, M.; Foken, Th.

    The objects of our investigations are five types of sonic anemometers that are widly used at present for turbulence measurements. These are the CSAT3 (Campbell Scien- tific), Solent HS (Gill Instruments), the NUW-Probe (NCAR), USA-1 (Metek) and the Model 81000 (R.M. Young). The main focus of this work was on the processing of the EBEX-2000 field intercomparison. In order to complete the characterisation of the instruments, the results of further intercomparison experiments were comparatively analysed and additionally three types of sonic anemometers were examined in a wind tunnel study. The highest measurement quality was found for the CSAT3 and the New UW-Probe. Other types of anemometers show significant deviations from the refer- ence, especially for the determination of fluctuations of the vertical wind component.

  12. Liquid Flow Meter based on a Thermal Anemometer Microsensor

    OpenAIRE

    Oleg Sazhin

    2016-01-01

    An analytical model of a thermal anemometer sensor is developed. A thermal anemometer microsensor utilizing doped polycrystalline silicon is created. A liquid flow meter prototype based on a thermal anemometer microsensor is designed. Results of the flow meter testing are presented.

  13. Rugged constant-temperature thermal anemometer.

    Science.gov (United States)

    Palma, J; Labbé, R

    2016-12-01

    Here we report a robust thermal anemometer which can be easily built. It was conceived to measure outdoor wind speeds and for airspeed monitoring in wind tunnels and other indoor uses. It works at a constant, low temperature of approximately 90 °C, so that an independent measurement of the air temperature is required to give a correct speed reading. Despite the size and high thermal inertia of the probe, the test results show that this anemometer is capable of measuring turbulent fluctuations up to ∼100 Hz in winds of ∼14 m/s, which corresponds to a scale similar to the length of the probe.

  14. Rugged constant-temperature thermal anemometer

    CERN Document Server

    Palma, J

    2016-01-01

    Here we report a robust thermal anemometer which can be easily built. It was conceived to measure outdoor wind speeds, and for airspeed monitoring in wind tunnels and other indoor uses. It works at a constant, low temperature of approximately 90$^\\circ$C, so that an independent measurement of the air temperature is required to give a correct speed reading. Despite the size and high thermal inertia of the probe, the test results show that this anemometer is capable of measuring turbulent fluctuations up to ~100 Hz in winds of ~14 m/s, which corresponds to a scale similar to the length of the probe.

  15. Calibration of a spinner anemometer for wind speed measurements

    DEFF Research Database (Denmark)

    Demurtas, Giorgio; Friis Pedersen, Troels; Zahle, Frederik

    2016-01-01

    The power curve of a wind turbine can be measured, according to IEC 61400-12-2 with a nacelle-mounted anemometer. Typically, a sonic anemometer or a cup anemometer and a wind vane are mounted on the back of the nacelle roof. Another option is to use a spinner anemometer. The measurement principle...... of the spinner anemometer is based on the flow distortion caused by the wind turbine spinner. The flow on the spinner surface is measured by means of three 1D sonic sensors mounted on the spinner and a conversion algorithm to convert the wind velocity components measured by the three sonic sensors to horizontal...

  16. A Procedure for Classification of Cup-Anemometers

    DEFF Research Database (Denmark)

    Friis Pedersen, Troels; Paulsen, Uwe Schmidt

    1997-01-01

    The paper proposes a classification procedure for cup-anemometers based on similar principles as for power converters. A range of operational parameters are established within which the response of the cup-anemometer is evaluated. The characteristics of real cup-anemometers are fitted...... to a realistic 3D cup-anemometer model. Afterwards, the model is used to calculate the response under the range of operational conditions which are set up for the classification. Responses are compared to the normal linear calibration relationship, derived from Wind tunnel calibrations. Results of the 3D cup-anemometer...

  17. Improved Circuit For Hot-Film Anemometer

    Science.gov (United States)

    Gray, David L.

    1993-01-01

    Circuit suitable for automation or computer control of setup and operation. Hot-film or hot-wire anemometer circuit features individual current drives for two arms of wheatstone bridge, plus other features that provide improved calibration and automated or computer-controlled operation.

  18. Hot-wire anemometer for spirography.

    Science.gov (United States)

    Plakk, P; Liik, P; Kingisepp, P H

    1998-01-01

    The use of a constant temperature hot-wire anemometer flow sensor for spirography is reported. The construction, operating principles and calibration procedure of the apparatus are described, and temperature compensation method is discussed. Frequency response is studied. It is shown that this hot-wire flow transducer satisfies common demands with respect to accuracy, response time and temperature variations.

  19. A simple nasal anemometer for clinical purposes.

    Science.gov (United States)

    Hutters, B; Brøndsted, K

    1992-01-01

    There is a need for clinical methods which give more direct information about the behaviour of the velopharyngeal mechanism in natural speech than do the examination methods normally applied to patients suffering from velopharyngeal insufficiency. One possibility is the recording of nasal airflow in order to detect nasal emission of air. The purpose of the present study is to examine the qualities and the characteristics of a simple and cheap nasal anemometer. As this type of flowmeter is considered less reliable than most other flowmeters, its limitations must be clearly understood and accounted for in drawing conclusions. Therefore, nasal airflow in speech obtained with this flowmeter is discussed in relation to nasal airflow obtained by the more reliable pneumotachograph and in relation to nasal airflow data found in the literature. The tests made here suggest that, at least for the type of speech material and measurements used in the present study, reliable nasal airflow data can be obtained by the anemometer.

  20. Sampling Bias on Cup Anemometer Mean Winds

    Science.gov (United States)

    Kristensen, L.; Hansen, O. F.; Højstrup, J.

    2003-10-01

    The cup anemometer signal can be sampled in several ways to obtain the mean wind speed. Here we discuss the sampling of series of mean wind speeds from consecutive rotor rotations, followed by unweighted and weighted averaging. It is shown that the unweighted averaging creates a positive bias on the long-term mean wind speed, which is at least one order of magnitude larger than the positive bias from the weighted averaging, also known as the sample-and-hold method. For a homogeneous, neutrally stratified flow the first biases are 1%-2%. For comparison the biases due to fluctuations of the three wind velocity components and due to calibration non-linearity are determined under the same conditions. The largest of these is the v-bias from direction fluctuations. The calculations pertain to the Risø P2546A model cup anemometer.

  1. Drag Force Anemometer Used in Supersonic Flow

    Science.gov (United States)

    Fralick, Gustave C.

    1998-01-01

    To measure the drag on a flat cantilever beam exposed transversely to a flow field, the drag force anemometer (beam probe) uses strain gauges attached on opposite sides of the base of the beam. This is in contrast to the hot wire anemometer, which depends for its operation on the variation of the convective heat transfer coefficient with velocity. The beam probe retains the high-frequency response (up to 100 kHz) of the hot wire anemometer, but it is more rugged, uses simpler electronics, is relatively easy to calibrate, is inherently temperature compensated, and can be used in supersonic flow. The output of the probe is proportional to the velocity head of the flow, 1/2 rho u(exp 2) (where rho is the fluid density and u is the fluid velocity). By adding a static pressure tap and a thermocouple to measure total temperature, one can determine the Mach number, static temperature, density, and velocity of the flow.

  2. Flow distortion on boom mounted cup anemometers

    Energy Technology Data Exchange (ETDEWEB)

    Lindeloew-Marsden, P.; Pedersen, Troels F.; Gottschall, J.; Vesth, A.; Paulsen, R.W.U.; Courtney, M.S.

    2010-08-15

    In this report we investigate on wind direction dependent errors in the measurement of the horizontal wind speed by boom mounted cup anemometers. The boom mounting on the studied lattice tower is performed according to IEC standard design rules, yet, larger deviations than predicted by flow models are observed. The errors on the measurements are likely caused by an underestimation of the flow distortions around the tower. In this paper an experimental method for deriving a correction formula and an in-field calibration is suggested. The method is based on measurements with two cup anemometers mounted with booms at the same height but pointing in 60 deg. different directions. In the examined case of a 1.9 m wide equilateral triangular lattice tower with booms protruding 4.1 m at 80 m height the measurement errors are observed to reach up to +- 2 %. Errors of this magnitude are severely problematic in the measurement of wind turbine power performance, wind resource assessment and for providing purposeful in-field comparisons between different sensors, e.g. lidar anemometers. With the proposed method, direction dependent errors can be extracted and the mast flow distortion effect on the wind measurements corrected to an uncertainty estimated to better than 0.5%. This level of uncertainty is probably acceptable for the above mentioned applications. (author)

  3. Distance constant of the Risø cup anemometer

    DEFF Research Database (Denmark)

    Kristensen, L.; Frost Hansen, O.

    2002-01-01

    The theory for cup-anemometer dynamics is presented in some detail and two methods of obtaining the distance constant lo are discussed. The first method is based on wind tunnel measurements: with a constant wind speed the cup anemometer is released from alocked position of the rotor...... and the increasing rotation rate recorded. It is concluded that the rapid increase in rotation rate makes the method very inaccurate. The second method consists of an analysis of turbulent, atmospheric of wind speed asmeasured by the cup anemometer and a fast-responding sonic anemometer with a spatial eddy...... resolution which is significantly better than that which can be obtained by a cup anemometer. The ratio between the measured power spectra of the horizontal windspeed by the two instruments contains the necessary information for determining the response characteristics of the cup anemometer and thereby lo...

  4. Quality, precision and accuracy of the maximum No. 40 anemometer

    Energy Technology Data Exchange (ETDEWEB)

    Obermeir, J. [Otech Engineering, Davis, CA (United States); Blittersdorf, D. [NRG Systems Inc., Hinesburg, VT (United States)

    1996-12-31

    This paper synthesizes available calibration data for the Maximum No. 40 anemometer. Despite its long history in the wind industry, controversy surrounds the choice of transfer function for this anemometer. Many users are unaware that recent changes in default transfer functions in data loggers are producing output wind speed differences as large as 7.6%. Comparison of two calibration methods used for large samples of Maximum No. 40 anemometers shows a consistent difference of 4.6% in output speeds. This difference is significantly larger than estimated uncertainty levels. Testing, initially performed to investigate related issues, reveals that Gill and Maximum cup anemometers change their calibration transfer functions significantly when calibrated in the open atmosphere compared with calibration in a laminar wind tunnel. This indicates that atmospheric turbulence changes the calibration transfer function of cup anemometers. These results call into question the suitability of standard wind tunnel calibration testing for cup anemometers. 6 refs., 10 figs., 4 tabs.

  5. Wind speed and direction measurements using the sphere anemometer

    Science.gov (United States)

    Heisselmann, Hendrik; Hoelling, Michael; Peinke, Joachim

    2009-11-01

    In times of growing energy demand, the importance of wind energy is rapidly increasing and so is the need for accurate wind speed and direction measurements. The widely spread cup anemometers show significant over-speeding under turbulent wind conditions as inherent in atmospherical flows while being solely capable of detecting the wind speed. Therefore, we propose the newly developed sphere anemometer as a simple an robust sensor for direction and velocity measurements. The sphere anemometer exploits the velocity-dependent deflection of a tube, which is the order of μm and can be detected by means of a light pointer as used in atomic force microscopes. In comparative measurements under laboratory conditions the sphere anemometer showed a significantly higher temporal resolution then cup anemometers while it does not exhibit any over-speeding. Additionally, results of atmospherical wind measurements with the sphere anemometer and state-of-the-art cup anemometry are presented.

  6. Validation of 3D sonic-anemometer against cup anemometer response

    DEFF Research Database (Denmark)

    Hansen, Kurt Schaldemose; Larsen, Gunner Chr.; Courtney, Michael

    2004-01-01

    Determination and validation of wind turbine power curves traditionally rely on single point wind speed measurements recorded with a calibrated cup-anemometer. The power curve verification process, which is typically performed in different terrain types, does not always result in satisfactory...... agreement between measures- and predicted power curves. The observed disagreement is premarily believed to relate to the cup-anemometers being sensitive to tilted flow i.e. that the measurement of the horizontal flow component is sensible to flow in a plane perpendicular to the horizontal plane. Furthermore......, the limited cup-anemometer response due to high turbulence can explain some of the diviations. The present paper investigates this problem, by analysing full-scale time series data extracted from "Database on Wind Characteristics" (http://www.winddata.com/), which represents a wide range of sites. Basically...

  7. Aerodynamic Analysis of Cup Anemometers Performance: The Stationary Harmonic Response

    OpenAIRE

    Santiago Pindado; Javier Cubas; Ángel Sanz-Andrés

    2013-01-01

    The effect of cup anemometer shape parameters, such as the cups’ shape, their size, and their center rotation radius, was experimentally analyzed. This analysis was based on both the calibration constants of the transfer function and the most important harmonic term of the rotor’s movement, which due to the cup anemometer design is the third one. This harmonic analysis represents a new approach to study cup anemometer performances. The results clearly showed a good correlation between the ave...

  8. Aerodynamic analysis of cup anemometers performance: the stationary harmonic response.

    Science.gov (United States)

    Pindado, Santiago; Cubas, Javier; Sanz-Andrés, Angel

    2013-01-01

    The effect of cup anemometer shape parameters, such as the cups' shape, their size, and their center rotation radius, was experimentally analyzed. This analysis was based on both the calibration constants of the transfer function and the most important harmonic term of the rotor's movement, which due to the cup anemometer design is the third one. This harmonic analysis represents a new approach to study cup anemometer performances. The results clearly showed a good correlation between the average rotational speed of the anemometer's rotor and the mentioned third harmonic term of its movement.

  9. Three-component laser anemometer measurement systems

    Science.gov (United States)

    Goldman, Louis J.

    1991-01-01

    A brief overview of the different laser anemometer (LA) optical designs available is presented. Then, the LA techniques that can be used to design a three-component measurement system for annular geometries are described. Some of the facility design considerations unique to these LA systems are also addressed. Following this, the facilities and the LA systems that were used to successfully measure the three components of velocity in the blading of annular-flow machines are reviewed. Finally, possible LA system enhancements and future research directions are presented.

  10. Method for fabricating a microscale anemometer

    Science.gov (United States)

    Liu, Chang (Inventor); Chen, Jack (Inventor)

    2008-01-01

    Method for fabricating a microscale anemometer on a substrate. A sacrificial layer is formed on the substrate, and a metal thin film is patterned to form a sensing element. At least one support for the sensing element is patterned. The sacrificial layer is removed, and the sensing element is lifted away from the substrate by raising the supports, thus creating a clearance between the sensing element and the substrate to allow fluid flow between the sensing element and the substrate. The supports are raised preferably by use of a magnetic field applied to magnetic material patterned on the supports.

  11. Mobile fiber-optic laser Doppler anemometer.

    Science.gov (United States)

    Stieglmeier, M; Tropea, C

    1992-07-20

    A laser Doppler anemometer (LDA) has been developed that combines the compactness and low power consumption of laser diodes and avalanche photodiodes with the flexibility and possibility of miniaturization by using fiber-optic probes. The system has been named DFLDA for laser diode fiber LDA and is especially suited for mobile applications, for example, in trains, airplanes, or automobiles. Optimization considerations of fiber-optic probes are put forward and several probe examples are described in detail. Measurement results from three typical applications are given to illustrate the use of the DFLDA. Finally, a number of future configurations of the DFLDA concept are discussed.

  12. Feature Extraction and Pattern Identification for Anemometer Condition Diagnosis

    Directory of Open Access Journals (Sweden)

    Longji Sun

    2012-01-01

    Full Text Available Cup anemometers are commonly used for wind speed measurement in the wind industry. Anemometer malfunctions lead to excessive errors in measurement and directly influence the wind energy development for a proposed wind farm site. This paper is focused on feature extraction and pattern identification to solve the anemometer condition diagnosis problem of the PHM 2011 Data Challenge Competition. Since the accuracy of anemometers can be severely affected by the environmental factors such as icing and the tubular tower itself, in order to distinguish the cause due to anemometer failures from these factors, our methodologies start with eliminating irregular data (outliers under the influence of environmental factors. For paired data, the relation between the relative wind speed difference and the wind direction is extracted as an important feature to reflect normal or abnormal behaviors of paired anemometers. Decisions regarding the condition of paired anemometers are made by comparing the features extracted from training and test data. For shear data, a power law model is fitted using the preprocessed and normalized data, and the sum of the squared residuals (SSR is used to measure the health of an array of anemometers. Decisions are made by comparing the SSRs of training and test data. The performance of our proposed methods is evaluated through the competition website. As a final result, our team ranked the second place overall in both student and professional categories in this competition.

  13. Two Ways Factorial Design for round robin test of anemometers

    Energy Technology Data Exchange (ETDEWEB)

    Cuerva, A.

    1998-07-01

    This work presents a way to carry out an inter-comparison between different cup anemometers that are tested in different wind tunnels. The method applied is known as Factorial design and allows determining the influence in the test of different factors in this case the anemometer itself and the wind tunnel where it is tested. (Author) 4 refs.

  14. Wind velocity measurements under turbulent conditions using a sphere anemometer

    Energy Technology Data Exchange (ETDEWEB)

    Heisselmann, Hendrik; Hoelling, Michael; Schulte, Bianca; Peinke, Joachim [Institute of Physics, University of Oldenburg (Germany)

    2008-07-01

    A well known problem of cup anemometry is the so-called overspeeding due to its momentum of inertia. As in nature turbulent flow conditions are predominant, cup anemometry leads to a wrong estimation of wind speeds. While cup anemometers do not provide the necessary time resolution to measure high frequency wind fluctuations, hot-wire anemometers are easily damaged under rough weather conditions. Therefore a robust, fast responding sphere anemometer was developed. The anemometer uses the thrust generated by the drag force on a sphere mounted on a flexible rod to detect wind velocities in two dimensions. The deflection of the rod is proportional to the drag force and can be measured either by means of a light pointer or by use of strain gauges. The two different measurement techniques were compared. The dynamic behaviour of the thrust anemometer was studied under laboratory conditions using a wind gust generator. The characteristics of different sphere-types and different rod materials were evaluated in order to optimize the setup. Results of open air measurements with hot-wire anemometer, sonic anemometer and sphere anemometer were compared by statistical methods.

  15. Evaluation of the sphere anemometer for atmospheric wind measurements

    Science.gov (United States)

    Heisselmann, Hendrik; Peinke, Joachim; Hoelling, Michael

    2014-11-01

    Our contribution will compare the sphere anemometer and two standard sensors for wind energy and meteorology based on data from a near-shore measurement campaign. We will introduce the characteristics of the sphere anemometer - a drag-based sensor for simultaneous wind speed and direction measurements, which makes use of the highly resolving light pointer principle to detect the velocity-dependent deflection of sphere mounted on a flexible tube. Sphere anemometer, cup anemometer and 3D sonic anemometer were installed at near-shore site in the German Wadden Sea. A comparison of the anemometers was carried out based on several month of high frequency data obtained from this campaign. The measured wind speed and direction data were analyzed to evaluate the capability of the sphere anemometer under real operating conditions, while the sensor characteristics obtained from previous wind tunnel experiments under turbulent conditions served as a reference to assess the durability and to identify challenges of the new anemometer. A characterization of the atmospheric wind conditions at the test site is performed based on the recorded wind data. Wind speed and wind direction averages and turbulence intensities are analyzed as well as power spectra and probability density functions. Supported by the German Ministry of Economics and Energy.

  16. Calibration of a spinner anemometer for yaw misalignment measurements

    DEFF Research Database (Denmark)

    Friis Pedersen, Troels; Demurtas, Giorgio; Zahle, Frederik

    2015-01-01

    The spinner anemometer is an instrument for yaw misalignment measurements without the drawbacks of instruments mounted on the nacelle top. The spinner anemometer uses a non-linear conversion algorithm that converts the measured wind speeds by three sonic sensors on the spinner to horizontal wind...... constant, k1, mainly affects the measurement of wind speed. The ratio between the two constants, kα = k2/k1, however, only affects the measurement of flow angles. The calibration of kα is thus a basic calibration of the spinner anemometer. Theoretical background for the non-linear calibration is derived...... from the generic spinner anemometer conversion algorithm. Five different methods were evaluated for calibration of a spinner anemometer on a 500 kW wind turbine. The first three methods used rotor yaw direction as reference angular, while the wind turbine, was yawed in and out of the wind. The fourth...

  17. Wind Powering America Anemometer Loan Program: A Retrospective

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez, T.

    2013-05-01

    This white paper details the history, mechanics, status, and impact of the Native American Anemometer Loan Program (ALP) conducted by the U.S. Department of Energy's Wind Powering America (WPA) initiative. Originally conceived in 2000 and terminated (as a WPA activity) at the end of FY 2011, the ALP has resulted in the installation of anemometers at 90 locations. In addition, the ALP provided support for the installation of anemometers at 38 additional locations under a related ALP administered by the Western Area Power Administration.

  18. Calibration and Lag of a Friez Type Cup Anemometer

    Science.gov (United States)

    Pinkerton, Robert M

    1930-01-01

    Tests on a Friez type cup anemometer have been made in the variable density wind tunnel of the Langley Memorial Aeronautical Laboratory to calibrate the instrument and to determine its suitability for velocity measurements of wind gusts. The instrument was calibrated against a Pitot-static tube placed directly above the anemometer at air densities corresponding to sea level, and to an altitude of approximately 6000 feet. Air-speed acceleration tests were made to determine the lag in the instrument reading. The calibration results indicate that there should be an altitude correction. It is concluded that the cup anemometer is too sluggish for velocity measurements of wind gusts.

  19. Cup anemometer calibration: effect of flow velocity distribution

    Science.gov (United States)

    Piccato, A.; Spazzini, P. G.; Malvano, R.

    2011-10-01

    The effects of different working conditions and specifically of different velocity profiles on the output of a commercial cup anemometer were analysed experimentally. A simple mathematical model is also presented and provides results in line with the experiments. Results show that a cup anemometer with certain geometrical features can be calibrated through a rotating drag rig by correcting for the bias on the instrument output. The increase in uncertainty caused by this systematic correction was evaluated and applied to the results. The correction was validated by checking the compatibility of calibrations of a cup anemometer at the rotating rig and in a wind tunnel.

  20. Aerodynamic Analysis of Cup Anemometers Performance: The Stationary Harmonic Response

    Directory of Open Access Journals (Sweden)

    Santiago Pindado

    2013-01-01

    Full Text Available The effect of cup anemometer shape parameters, such as the cups’ shape, their size, and their center rotation radius, was experimentally analyzed. This analysis was based on both the calibration constants of the transfer function and the most important harmonic term of the rotor’s movement, which due to the cup anemometer design is the third one. This harmonic analysis represents a new approach to study cup anemometer performances. The results clearly showed a good correlation between the average rotational speed of the anemometer’s rotor and the mentioned third harmonic term of its movement.

  1. Aerodynamic Investigation of a Cup Anemometer

    Science.gov (United States)

    Hubbard, John D; Brescoll, George P

    1934-01-01

    This thesis presents the results of an investigation wherein the change of the normal force coefficient with Reynolds Number was obtained statically for a 15.5-centimeter hemisphere cup under the following conditions: (1) single cup with no interference; (2) single cup with three-cup interference; (3) four cups. The coefficients found in this research vary with Reynolds Number and are high as compared with those of Eiffel. The effect of interference upon a single cup is to increase the drag and normal force coefficients. The curve resulting from the summation of the coefficients for four cups agrees with the static torque curve of a Robinson type cup anemometer. All tests were carried on in the University of Detroit atmospheric wind tunnel during May 1933.

  2. Can a cup anemometer 'underspeed'? A heretical question

    DEFF Research Database (Denmark)

    Kristensen, L.

    2002-01-01

    An analysis of cup-anemometer dynamics has been carried out in order to determine whether the mean-wind velocity can have a negative bias. This would be contrary to the general belief that cup anemometers always overspeed. Compared to prior analyses, the effect of a possible nonlinearity...... of the calibration function is included. The conclusion is that neither longitudinal nor lateral velocity fluctuations can contribute significantly to a negative bias. However, if a cup anemometer has an angular response that falls below the ideal cosine response, there will, as demonstrated in the concluding...... discussion, be a negative contribution from the vertical velocity fluctuations to the total bias, and this contribution may even outbalance the positive contributions from the longitudinal velocity fluctuations. Concrete evidence of such exotic cup anemometer behaviour has not been reported in the literature....

  3. Fast-response cup anemometer features cosine response

    Science.gov (United States)

    Frenzen, P.

    1968-01-01

    Six-cup, low-inertia anemometer combines high resolution and fast response with a unique ability to sense only the horizontal component of the winds fluctuating rapidly in three dimensions. Cup assemblies are fabricated of expanded polystyrene plastic.

  4. Distance constant of the Risø cup anemometer

    OpenAIRE

    Kristensen, L.; Frost Hansen, O.

    2002-01-01

    The theory for cup-anemometer dynamics is presented in some detail and two methods of obtaining the distance constant lo are discussed. The first method is based on wind tunnel measurements: with a constant wind speed the cup anemometer is released from alocked position of the rotor and the increasing rotation rate recorded. It is concluded that the rapid increase in rotation rate makes the method very inaccurate. The second method consists of an analysis of turbulent, atmospheric of wind spe...

  5. Fourier analysis of the aerodynamic behavior of cup anemometers

    OpenAIRE

    Pindado Carrion, Santiago; Pérez Sarasola, Imanol; Aguado Roca, Maite

    2013-01-01

    The calibration results (the transfer function) of an anemometer equipped with several cup rotors were analyzed and correlated with the aerodynamic forces measured on the isolated cups in a wind tunnel. The correlation was based on a Fourier analysis of the normal-to-the-cup aerodynamic force. Three different cup shapes were studied: typical conical cups, elliptical cups and porous cups (conical-truncated shape). Results indicated a good correlation between the anemometer factor, K, and the r...

  6. Removal of pedestals and directional ambiguity of optical anemometer signals.

    Science.gov (United States)

    Durst, F; Zaré, M

    1974-11-01

    Laser Doppler anemometry permits, in principle, the measurement of both magnitude and direction of components of a particle's velocity vector. Most exiting anemometers, however, permit measurements only with a directional ambiguity of 180 degrees , resulting in errors in certain flow fields. Available methods of eliminating the directional ambiguity of Laser Doppler anemometers are reviewed, covering frequency shifting of the incident and scattered light beams, the use of beams with different polarization properties, and employment of multicolor laser beams. The advantages and disadvantages of existing methods are summarized, and suggestions for alterations are made. Different techniques used to remove the pedestal of laser Doppler anemometer signals are also reviewed. Optical techniques should be employed in any advanced optical anemometer system to avoid dynamic range limitations by electronic bandpass filters. Suggestions are made for advanced optical anemometers employing multielement avalanche photodiodes that can be used for simultaneous measurements of two velocity components. These anemometers incorporate devices to sense the direction of the velocity components and to eliminate optically the pedestal of laser Doppler signals.

  7. Development of a classification system for cup anemometers - CLASSCUP

    DEFF Research Database (Denmark)

    Friis Pedersen, Troels

    2003-01-01

    Errors associated with the measurements of the wind speed are the major sources of uncertainties in power performance testing of wind turbines. Field comparisons of well-calibrated anemometers show a significant and not acceptable difference. TheEuropean CLASSCUP research project posed the object......Errors associated with the measurements of the wind speed are the major sources of uncertainties in power performance testing of wind turbines. Field comparisons of well-calibrated anemometers show a significant and not acceptable difference. TheEuropean CLASSCUP research project posed...... the objectives to quantify the errors associated with the use of cup anemometers, and to determine the requirements for an optimum design of a cup anemometer, and to develop a classification system forquantification of systematic errors of cup anemometers. The present report describes this proposed...... classification system. A classification method for cup anemometers has been developed, which proposes general external operational ranges to be used. Anormal category range connected to ideal sites of the IEC power performance standard was made, and another extended category range for complex terrain...

  8. Classification of operational characteristics of commercial cup-anemometers

    Energy Technology Data Exchange (ETDEWEB)

    Friis Pedersen, T.; Schmidt Paulsen, U. [Risoe National Lab., Wind Energy and Atmospheric Physics Dept., Roskilde (Denmark)

    1999-03-01

    The present classification of cup-anemometers is based on a procedure for classification of operational characteristics of cup-anemometers that was proposed at the EWEC `97 conference in Dublin 1997. Three definitions of wind speed are considered. The average longitudinal wind speed (ID), the average horizontal wind speed (2D) and the average vector wind speed (3D). The classification is provided in these terms, and additionally, the turbulence intensities, which are defined from the same wind speed definitions. The commercial cup-anemometers have all been calibrated in wind tunnel for the normal calibrations and angular characteristics. Friction was measured by blywheel testing, where the surrounding temperatures were varied over a wide range. The characteristics of the cup-anemometers have been fitted to the heuristic dynamic model, and the response has been calculated in time domain for prescribed ranges of external operational conditions. The results are presented in ranges of maximum deviations of `measured` average wind speed. For each definition of wind speed and turbulence intensity, the cup-anemometers are ranked according to the most precise instrument. Finally, the most important systematic error sources are commented. (au)

  9. Characterisation and classification of RISØ P2546 cup anemometer

    DEFF Research Database (Denmark)

    Friis Pedersen, Troels

    2003-01-01

    The characteristics of the RISØ P2546 cup anemometer were investigated in detail by wind tunnel and laboratory tests. The characteristics include accredited calibration, tilt response measurements for tilt angles between -40° to 40°, gust responsemeasurements at 8m/s and turbulence intensities...... of 10%, 16% and 23%, step response measurements at step wind speeds 3,7, 8, 11,9 and 15,2m/s, measurement of torque characteristics at 8m/s, rotor inertia measurements and measurements of friction ofbearings at temperatures -20°C to 40°C. Characteristics were fitted to a time domain cup anemometer model....... The characteristics were transformed into the CLASSCUP classification scheme, and were related to the cup anemometer requirements in the Danishcertification system and in the IEC 61400-121 Committee Draft....

  10. Nacelle power curve measurement with spinner anemometer and uncertainty evaluation

    DEFF Research Database (Denmark)

    Demurtas, Giorgio; Friis Pedersen, Troels; Wagner, Rozenn

    2016-01-01

    The objective of this investigation was to verify the feasibility of using the spinner anemometer calibration and nacelle transfer function determined on one reference turbine, to assess the power performance of a second identical turbine. An experiment was set up with a met-mast in a position...... suitable to measure the power curve of the two wind turbines, both equipped with a spinner anemometer. An IEC 61400-12-1 compliant power curve was then measured for both turbines using the met-mast. The NTF (Nacelle Transfer Function) was measured on the reference turbine and then applied to both turbines...... to calculate the free wind speed. For each of the two wind turbines, the power curve (PC) was measured with the met-mast and the nacelle power curve (NPC) with the spinner anemometer. Four power curves (two PC and two NPC) were compared in terms of AEP (Annual Energy Production) for a Rayleigh wind speed...

  11. Characterisation and classification of RISØ P2546 cup anemometer

    DEFF Research Database (Denmark)

    Friis Pedersen, Troels

    2004-01-01

    The characteristics of the RISØ P2546 cup anemometer were investigated in detail by wind tunnel and laboratory tests. The characteristics include accredited calibration, tilt response measurements for tilt angles between -40° to 40°, gust responsemeasurements at 8m/s and turbulence intensities...... of 10%, 16% and 23%, step response measurements at step wind speeds 3,7, 8, 11,9 and 15,2m/s, measurement of torque characteristics at 8m/s, rotor inertia measurements and measurements of friction ofbearings at temperatures -20°C to 40°C. Characteristics were fitted to a time domain cup anemometer model....... The characteristics were transformed into the CLASSCUP classification scheme, and were related to the cup anemometer requirements in the Danishcertification system and in the IEC 61400-121 Committee Draft....

  12. A dual-amplifier hot-wire anemometer

    Science.gov (United States)

    Sadeh, W. Z.; Finn, C. L.

    1979-01-01

    The conceptual design of a dual-amplifier constant-temperature hot-wire anemometer is described. This hot-wire anemometer consists of three basic independent modules: a Wheatstone bridge in which the hot wire is one of its arms, an error-correction amplifier, and a voltage-controlled current source. The last two modules constitute the feedback network of this hot-wire anemometer. Thus the output voltage across the wire is a true function of the instantaneous changes in the wire resistance induced by the cooling effect of the flow. The dual-amplifier is capable of reaching relatively high frequency response through adequate selection of its active elements. Suitable gain of the error-correction amplifier and proper choice of the transfer function of the current source has yielded a frequency bandwidth up to 200 kHz.

  13. Characterisation and classification of RISOe P2546 cup anemometer

    Energy Technology Data Exchange (ETDEWEB)

    Friis Pedersen, T.

    2003-04-01

    The characteristics of the RISOe P2546 cup anemometer were investigated in detail by wind tunnel and laboratory tests. The characteristics include accredited calibration, tilt response measurements for tilt angles between -40 degC to 40 degC, gust response measurements at 8m/s and turbulence intensities of 10%, 16% and 23%, step response measurements at step wind speeds 3,7, 8, 11,9 and 15,2m/s, measurement of torque characteristics at 8m/s, rotor inertia measurements and measurements of friction of bearings at temperatures -20 degC to 40 degC. Characteristics were fitted to a time domain cup anemometer model. The characteristics were transformed into the CLASSCUP classification scheme, and were related to the cup anemometer requirements in the Danish certification system and in the IEC 61400-121 Committee Draft. (au)

  14. Determining the Velocity Fine Structure by a Laser Anemometer with Fixed Orientation

    DEFF Research Database (Denmark)

    Kristensen, Leif; Kirkegaard, Peter; Mikkelsen, Torben

    We have studied the velocity structure functions and spectra which can be determined by a CW-laser anemometer and a (pulsed) lidar anemometer. We have found useful theoretical expressions for both types of anemometers and compared their filtering of the alongbeam turbulent velocity. The purpose has...

  15. Flush-mounted hot film anemometer accuracy in pulsatile flow.

    Science.gov (United States)

    Nandy, S; Tarbell, J M

    1986-08-01

    The accuracy of a flush-mounted hot film anemometer probe for wall shear stress measurements in physiological pulsatile flows was evaluated in fully developed pulsatile flow in a rigid straight tube. Measured wall shear stress waveform based on steady flow anemometer probe calibrations were compared to theoretical wall shear stress waveforms based on well-established theory and measured flow rate waveforms. The measured and theoretical waveforms were in close agreement during systole (average deviation of 14 percent at peak systole). As expected, agreement was poor during diastole because of flow reversal and diminished frequency response at low shear rate.

  16. New hot wire anemometer with alternate current and synchronic detection

    Science.gov (United States)

    Stoian, Monica; Rachek, Adil; Chirtoc, Mihai

    2009-01-01

    The feasibility of hot wire anemometer in to a new measurement configuration is demonstrated in this work and we validate our results by a numerical model. We have created an anemometer probe with hot wire using a new scheme, in alternate current and synchronic detection (3ω method). We use this instrument to register the velocity magnitude in boundary layer for a forced convection flow. The probe and its alimentation also the measuring support and bridge Wheatstone, have been created by us. The physical parameter was recorded is an exchange heat quantity between hot wire and fluid flow. In steady state, experimental data verify the numerical results with an average error of 3%.

  17. Fourier analysis of the aerodynamic behavior of cup anemometers

    Science.gov (United States)

    Pindado, Santiago; Pérez, Imanol; Aguado, Maite

    2013-06-01

    The calibration results (the transfer function) of an anemometer equipped with several cup rotors were analyzed and correlated with the aerodynamic forces measured on the isolated cups in a wind tunnel. The correlation was based on a Fourier analysis of the normal-to-the-cup aerodynamic force. Three different cup shapes were studied: typical conical cups, elliptical cups and porous cups (conical-truncated shape). Results indicated a good correlation between the anemometer factor, K, and the ratio between the first two coefficients in the Fourier series decomposition of the normal-to-the-cup aerodynamic force.

  18. Constant-bandwidth constant-temperature hot-wire anemometer.

    Science.gov (United States)

    Ligeza, P

    2007-07-01

    A constant-temperature anemometer (CTA) enables the measurement of fast-changing velocity fluctuations. In the classical solution of CTA, the transmission band is a function of flow velocity. This is a minor drawback when the mean flow velocity does not significantly change, though it might lead to dynamic errors when flow velocity varies over a considerable range. A modification is outlined, whereby an adaptive controller is incorporated in the CTA system such that the anemometer's transmission band remains constant in the function of flow velocity. For that purpose, a second feedback loop is provided, and the output signal from the anemometer will regulate the controller's parameters such that the transmission bandwidth remains constant. The mathematical model of a CTA that has been developed and model testing data allow a through evaluation of the proposed solution. A modified anemometer can be used in measurements of high-frequency variable flows in a wide range of velocities. The proposed modification allows the minimization of dynamic measurement errors.

  19. Research on the Plasma Anemometer Based on AC Glow Discharge

    Directory of Open Access Journals (Sweden)

    Bing Yu

    2017-01-01

    Full Text Available A new plasma anemometer based on AC glow discharge is designed in this article. Firstly, theoretical analysis of plasma anemometer working principle is introduced to prove the feasibility of the experimental measurement method. Then the experiments are carried out to study the effects of different parameters on the static discharge characteristics of the plasma anemometer system, by which the system optimization methods are obtained. Finally, several groups of appropriate parameters are selected to build the plasma anemometer system based on resistance capacitance coupling negative feedback AC glow discharge, and different airflow speeds are applied to obtain the achievable velocity measurement range. The results show that there is a linear relationship between airflow velocity and discharge current in an allowable error range, which can be applied for airflow velocity measurement. Negative feedback coupling module, which is composed of the coupling resistance and the coupling capacitance, has good effects on improving the system stability. The measurement range of the airflow velocity is significantly increased when the electrode gap is 3 mm, coupling resistance is 470 Ω, and coupling capacitance is 220 pF.

  20. Influence of the Meteorology Mast on a Cup Anemometer

    DEFF Research Database (Denmark)

    Hansen, Martin O. L.; Pedersen, B.M.

    1999-01-01

    The actuator disc model is applied on lattice-type meteorological masts to estimate the influence of the tower on the accuracy of the measured wind speed. Combining the results with corrections for the boom, on which the anemometer is mounted, good agreement is found for measurements made...

  1. Spectral Coherence Along a Lidar-Anemometer Beam

    DEFF Research Database (Denmark)

    Kristensen, Leif; Kirkegaard, Peter; Mann, Jakob

    The theory of measuring the spectral coherence by means of a lidar anemometer has been outlined. It is based on the assumption that the turbulent velocity field can be considered statistically locally isotropic and on the validity of Taylor’s hypothesis. This implies that the longitudinal coherence...

  2. Characterisation and classification of RISOe P2546 cup anemometer

    Energy Technology Data Exchange (ETDEWEB)

    Friis Pedersen, T.

    2004-03-01

    The characteristics of the RISOe P2546 cup anemometer were investigated in detail, and all data presented in figures and tables. The characteristics include: wind tunnel calibrations, including an accredited calibration; tilt response meas-urements for tilt angles from -40 deg. C to 40 deg. C; gust response measurements at 8m/s, 10,5m/s and 13m/s and turbulence intensities of 10%, 16% and 23%; step response measurements at step wind speeds 4, 8, 12 and 15m/s; measurement of torque characteristics at 8m/s; rotor inertia measurements and measurements of friction of bearings at temperatures -20 deg. C to 40 deg. C. The characteristics are fitted to a time domain cup anemometer model, and the cup anemometer is put into the CLASSCUP classification scheme. The characteristics are also compared to the requirements to cup anemometers in the Danish wind turbine certification system and the CD and CDV of the revision of the standard IEC 61400-12. (au)

  3. Improved analytical method to study the cup anemometer performance

    Science.gov (United States)

    Pindado, Santiago; Ramos-Cenzano, Alvaro; Cubas, Javier

    2015-10-01

    The cup anemometer rotor aerodynamics is analytically studied based on the aerodynamics of a single cup. The effect of the rotation on the aerodynamic force is included in the analytical model, together with the displacement of the aerodynamic center during one turn of the cup. The model can be fitted to the testing results, indicating the presence of both the aforementioned effects.

  4. An innovative method to calibrate a spinner anemometer without the use of yaw position sensor

    DEFF Research Database (Denmark)

    Demurtas, Giorgio; Janssen, Nick Gerardus Cornelis

    2016-01-01

    A spinner anemometer can be used to measure the yaw misalignment and flow inclination experienced by a wind turbine. Previous calibration methods used to calibrate a spinner anemometer for flow angle measurements were based on measurements of a spinner anemometer with default settings (arbitrary...... values, generally k1,d  =  1 and k2,d  =  1) and a reference yaw misalignment signal measured with a yaw position sensor. The yaw position sensor is normally present in wind turbines for control purposes; however, such a signal is not always available for a spinner anemometer calibration. Therefore......, an additional yaw position sensor was installed prior to the spinner anemometer calibration. An innovative method to calibrate the spinner anemometer without a yaw positions sensor was then developed. It was noted that a non-calibrated spinner anemometer that overestimates (underestimates) the inflow angle...

  5. An innovative method to calibrate a spinner anemometer without use of yaw position sensor

    DEFF Research Database (Denmark)

    Demurtas, Giorgio; Cornelis Janssen, Nick Gerardus

    2016-01-01

    A spinner anemometer can be used to measure the yaw misalignment and flow inclination experienced by a wind turbine. Previous calibration methods used to calibrate a spinner anemometer for flow angle measurements were based on measurements of a spinner anemometer with default settings...... and a reference yaw misalignment signal measured measured with a yaw position sensor. The yaw position sensor is normally present in wind turbines for control purposes, however, such a signal is not always available for a spinner anemometer calibration. Therefore, an additional yaw position sensor has been...... installed prior to the spinner anemometer calibration. An innovative method to calibrate the spinner anemometer without a yaw positions sensor was then developed. It was noted that a non calibrated spinner anemometer that overestimate (underestimate) the inflow angle will also overestimate (underestimate...

  6. The cup anemometer, a fundamental meteorological instrument for the wind energy industry. Research at the IDR/UPM Institute.

    Science.gov (United States)

    Pindado, Santiago; Cubas, Javier; Sorribes-Palmer, Félix

    2014-11-12

    The results of several research campaigns investigating cup anemometer performance carried out since 2008 at the IDR/UPM Institute are included in the present paper. Several analysis of large series of calibrations were done by studying the effect of the rotor's geometry, climatic conditions during calibration, and anemometers' ageing. More specific testing campaigns were done regarding the cup anemometer rotor aerodynamics, and the anemometer signals. The effect of the rotor's geometry on the cup anemometer transfer function has been investigated experimentally and analytically. The analysis of the anemometer's output signal as a way of monitoring the anemometer status is revealed as a promising procedure for detecting anomalies.

  7. The Cup Anemometer, a Fundamental Meteorological Instrument for the Wind Energy Industry. Research at the IDR/UPM Institute

    Science.gov (United States)

    Pindado, Santiago; Cubas, Javier; Sorribes-Palmer, Félix

    2014-01-01

    The results of several research campaigns investigating cup anemometer performance carried out since 2008 at the IDR/UPM Institute are included in the present paper. Several analysis of large series of calibrations were done by studying the effect of the rotor's geometry, climatic conditions during calibration, and anemometers' ageing. More specific testing campaigns were done regarding the cup anemometer rotor aerodynamics, and the anemometer signals. The effect of the rotor's geometry on the cup anemometer transfer function has been investigated experimentally and analytically. The analysis of the anemometer's output signal as a way of monitoring the anemometer status is revealed as a promising procedure for detecting anomalies. PMID:25397921

  8. 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)

  9. Method of Assembling a Silicon Carbide High Temperature Anemometer

    Science.gov (United States)

    Okojie, Robert S. (Inventor); Fralick, Gustave C. (Inventor); Saad, George J. (Inventor)

    2004-01-01

    A high temperature anemometer includes a pair of substrates. One of the substrates has a plurality of electrodes on a facing surface, while the other of the substrates has a sensor cavity on a facing surface. A sensor is received in the sensor cavity, wherein the sensor has a plurality of bondpads, and wherein the bondpads contact the plurality of electrodes when the facing surfaces are mated with one another. The anemometer further includes a plurality of plug-in pins, wherein the substrate with the cavity has a plurality of trenches with each one receiving a plurality of plug-in pins. The plurality of plug-in pins contact the plurality of electrodes when the substrates are mated with one another. The sensor cavity is at an end of one of the substrates such that the sensor partially extends from the substrate. The sensor and the substrates are preferably made of silicon carbide.

  10. All semiconductor laser Doppler anemometer at 1.55 microm.

    Science.gov (United States)

    Hansen, René Skov; Pedersen, Christian

    2008-10-27

    We report to our best knowledge the first all semiconductor Laser Doppler Anemometer (LIDAR) for wind speed determination. We will present the design and first experimental results on a focusing coherent cw laser Doppler anemometer for measuring atmospheric wind velocities in the 10 meters to 300 meters distance range. Especially, we will demonstrate that both the output power as well as the demanding coherence properties required from the laser source can be accomplished by an all semiconductor laser. Preliminary tests at a distance of 40 meters indicate a typical signal to noise ratio of 9 dB. This result is obtained at a clear day with an up-date rate of 12 Hz.

  11. The Sphere Anemometer - A Fast Alternative to Cup Anemometry

    Science.gov (United States)

    Heißelmann, Hendrik; Hölling, Michael; Peinke, Joachim

    The main problem of cup anemometry is the different response time for increasing and decreasing wind velocities due to its moment of inertia. This results in an overestimation of wind speed under turbulent wind conditions, the so-called over-speeding. Additionally, routine calibrations are necessary due to the wear of bearings. Motivated by these problems the sphere anemometer, a new simple and robust sensor for wind velocity measurements without moving parts, was developed at the University of Oldenburg. In contrast to other known thrust-based sensors, the sphere anemometer uses the light pointer principle to detect the deflection of a bending tube caused by the drag force acting on a sphere mounted at its top. This technique allows the simultaneous determination of wind speed and direction via a two-dimensional position sensitive detector.

  12. Nonlinear theory of a hot-wire anemometer

    Science.gov (United States)

    Betchov, R

    1952-01-01

    A theoretical analysis is presented for the hot-wire anemometer to determine the differences in resistance characteristics as given by King's equation for an infinite wire length and those given by the additional considerations of (a) a finite length of wire with heat loss through its ends and (b) heat loss due to a nonlinear function of the temperature difference between the wire and the air.

  13. Experimental Investigation of the Robinson-Type Cup Anemometer

    Science.gov (United States)

    Brevoort, M J; Joyner, U T

    1936-01-01

    This report presents the results of wind tunnel tests on a Robinson-type anemometer. The investigation covered force measurements on individual cups, as well as static and dynamic torque measurements and calibrations on complete cup wheels. In the tests on individual cups 5 cup forms were used and in the measurements on complete cup wheels 4 cup wheels with 3 arm lengths for each cup wheel were tested. All the results are presented in graphical form.

  14. Effects of Turbulence and Flow Inclination on the Performance of Cup Anemometers in the Field

    Science.gov (United States)

    Papadopoulos, K.H.; Stefantos, N.C.; Paulsen, U.S.; Morfiadakis, E.

    Four commercial and one research cup anemometers were comparatively tested in a complex terrain site to quantify the effects of turbulence and flow inclination on the wind speed measurements. The difference of the mean windspeed reading between the anemometers was as much as 2% for wind directions where the mean flow was horizontal. This difference was large enough to be attributed to the well-known overspeeding effect related to the differing distance constant (ranging from 1.7 to 5 m) of the cup anemometers. The application of a theoretical model of the cup-anemometer behaviour in athree-dimensional turbulent wind field proved successful in explaining theobserved differences.Additional measurements were taken with the anemometers tilted at known angles into and out of the incident wind flow. Thus, a field-derived angular response curve is constructed for each anemometer and the deviations from publishedwind-tunnel results are discussed.

  15. Development of a standardised cup anemometer suited to wind energy applications. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Dahlberg, J.Aa.; Gustavsson, J.; Ronsten, G. [Aeronautical Research Inst. of Sweden, Bromma (Sweden); Friis Pedersen, T.; Schmidt Paulsen, U. [Risoe National Laboratory, Roskilde (Denmark); Westermann, D. [German Wind Energy Inst., Wilhelmshaven (Germany)

    2002-05-01

    Errors associated with the measurements and interpretation of the measured wind speed are the major sources of uncertainties in power performance testing of wind turbines. Field comparisons of well calibrated anemometers of different types often show significant and not acceptable differences. The objective were to determine the optimum design for a cup anemometer which should be free from the design faults associated with all of the instruments currently commercially available. The objective were also to prepare a classification system for cup anemometers which will allow users of anemometry in the wind energy field to rank and select anemometers suited to specific required applications. The extensive experiments including tests in wind tunnels, of more than 500 anemometer configurations, fields tests and tests in laboratories together with the assessment and modelling work have helped to build up a thorough knowledge of the importance of different design parameters in terms of various behavioural effects. Influenced by trends from the international standardisation work, an early decision was made to focus on a vector, 3D, (angle-insensitive anemometer) cup-anemometer and to focus on conical cups since their sensitivity to vertical velocity components appeared to be less sensitive to the wind speed. The key measures taken to develop the new design consisted of an appropriate selection of the detailed design of the cup geometry's and mounting the cups at appropriate radius on a slender symmetric body. The development finally ended with an anemometer that gave a very good flat response within 1 % over the range from -45 deg to +35 deg and had a good linear calibration curve. Four prototypes of the anemometer optimised for flat response were produced. The flat response was also confirmed by field tests over the range {+-}20 deg. A patent application of the new anemometer was filed on the 6th of October 2000. By the time the project was initiated there was a

  16. Determining the velocity fine structure by a laser anemometer with fixed orientation

    Energy Technology Data Exchange (ETDEWEB)

    Kristensen, Leif; Kirkegaard, P.; Mikkelsen, Torben

    2011-02-15

    We have studied the velocity structure functions and spectra which can be determined by a CW-laser anemometer and a (pulsed) lidar anemometer. We have found useful theoretical expressions for both types of anemometers and compared their filtering of the along-beam turbulent velocity. The purpose has been to establish a basis for remote determining of turbulence fine-structure in terms of the rate of dissipation of specific kinetic energy in the atmospheric boundary layer. (Author)

  17. Identification of Tower Wake Distortions Using Sonic Anemometer and Lidar Measurements

    OpenAIRE

    McCaffrey, Katherine; Quelet, Paul; Choukulkar, Aditya; Wilczak, James M.; Wolfe, Daniel E.; Oncley, Steven; Brewer, Alan; Debnath, Mithu; Ashton, Ryan; Iungo, G. Valerio; Lundquist, Julie K.

    2016-01-01

    The eXperimental Planetary boundary layer Instrumentation Assessment (XPIA) field campaign took place in March through May 2015 at the Boulder Atmospheric Observatory, utilizing its 300-meter meteorological tower, instrumented with two sonic anemometers mounted on opposite sides of the tower at six heights. This allowed for at least one sonic anemometer at each level to be upstream of the tower at all times, and for identification of the times when a sonic anemometer is in the wake of the tow...

  18. Turbulence Measurements in the Atmospheric Surface Layer by Means of an Ultrasonic Anemometer and Thermometer

    Science.gov (United States)

    2006-02-01

    C., 1981: Cup , propeller, vane, and sonic anemometers in turbulence research. Annual Review of Fluid Mechanics, 13, 399–423, doi:10.1146/annurev.fl.13.010181.002151. 91 ...REPORT Turbulence measurements in the atmospheric surface layer by means of an ultrasonic anemometer and thermometer 14. ABSTRACT 16. SECURITY...ultrasonic anemometer /thermometers ("sonics"). The system performance was quantified by comparing observed turbulence spectra with inertial-range

  19. SiC-Based Miniature High-Temperature Cantilever Anemometer

    Science.gov (United States)

    Okojie, Robert S.; Fralick, Gustave; Saad, George J.

    2004-01-01

    The figure depicts a miniature cantilever-type anemometer that has been developed as a prototype of compact, relatively nonintrusive anemometers that can function at temperatures up to 600 C and that can be expected to be commercially mass-producible at low cost. The design of this anemometer, and especially the packaging aspect of the design, is intended to enable measurement of turbulence in the high-temperature, high-vibration environment of a turbine engine or in any similar environment. The main structural components of the anemometer include a single-crystal SiC cantilever and two polycrystalline SiC clamping plates, all made from chemical-vapor-deposited silicon carbide. Fabrication of these components from the same basic material eliminates thermal-expansion mismatch, which has introduced spurious thermomechanical stresses in cantilever-type anemometers of prior design. The clamping plates are heavily oxidized to improve electrical insulation at high temperature. A cavity that serves as a receptacle for the clamped end of the cantilever is etched into one end of one clamping plate. Trenches that collectively constitute a socket for a multipin electrical plug (for connection to external electronic circuitry) are etched into the opposite end of this clamping plate. Metal strips for electrical contact are deposited on one face of the other clamping plate. Piezoresistive single-crystal SiC thin-film strain gauges are etched in the n-type SiC epilayer in a Wheatstone-bridge configuration. Metal contact pads on the cantilever that extend into the clamping-receptacle area, are obtained by deposition and patterning using standard semiconductor photolithography and etching methods. The cantilever and the two clamping plates are assembled into a sandwich structure that is then clamped in a stainless-steel housing. The Wheatstone- bridge carrying SiC cantilever with the metal contact pads on the piezoresistors is slid into the receptacle in the bottom clamping plate

  20. Comparison of three velocity measurement systems - A laser transit anemometer (LTA), an on axis laser Doppler anemometer (LDA) and a constant temperature hot-wire anemometer (CTA)

    Science.gov (United States)

    Bennett, M. J.; Mawlood, S. N.; Al-Daini, A. J.; Girgis, N. S.

    Three flow-velocity measurement systems, an on-axis LDA, an LTA, and a constant temperature hot-wire anemometer (CTA), are described and compared by applying them to the measurement of velocity in a high-pressure closed-circuit wind tunnel and to the velocity profiles of a free jet. A system operating on the LTA principle, the Polytec L2F, was used to produce the probability density functions for the two flow situations and to calibrate the hot-wire CTA system, and the hot-wire calibration curve at normal pressure and temperature was used to develop a semiempirical model for the evaluation of velocity at elevated pressures and temperatures. An experimental arrangement in which LTA and LDA measuring systems may be used simultaneously with no separation of the respective measuring volumes in any axis is described, and the methods which may be used to counteract the inaccuracies of such an arrangement are discussed.

  1. Laser Doppler anemometer measurements using nonorthogonal velocity components: error estimates.

    Science.gov (United States)

    Orloff, K L; Snyder, P K

    1982-01-15

    Laser Doppler anemometers (LDAs) that are arranged to measure nonorthogonal velocity components (from which orthogonal components are computed through transformation equations) are more susceptible to calibration and sampling errors than are systems with uncoupled channels. In this paper uncertainty methods and estimation theory are used to evaluate, respectively, the systematic and statistical errors that are present when such devices are applied to the measurement of mean velocities in turbulent flows. Statistical errors are estimated for two-channel LDA data that are either correlated or uncorrelated. For uncorrelated data the directional uncertainty of the measured velocity vector is considered for applications where mean streamline patterns are desired.

  2. [How reliable is a hot-wire anemometer?].

    Science.gov (United States)

    von Rechenberg, H; Konder, H; Höser, K; Lennartz, H

    1985-08-01

    To examine the advantage of hot-wire anemometer for clinical use, we have checked two types of this tools with respect to reliability and validity. It was found that electronic suppression of noise caused a distortion of the measurements. Furthermore changes of transducers were also responsible for deviations from true values. We require of the manufacturer to indicate the threshold of perception and the coefficient of variation for repeated measurements with several transducers. We recommend a simple rule which permits an estimation of the limits of reliable measurements for clinical use depending on the threshold of the equipment and on the parameters of ventilation.

  3. Spectral coherence along a lidar-anemometer beam

    Energy Technology Data Exchange (ETDEWEB)

    Kristensen, Leif; Kirkegaard, P.; Mann, J.; Mikkelsen, Torben; Nielsen, Morten; Sjoeholm, M.

    2010-10-15

    The theory of measuring the spectral coherence by means of a lidar anemometer has been outlined. It is based on the assumption that the turbulent velocity field can be considered statistically locally isotropic and on the validity of Taylor's hypothesis. This implies that the longitudinal coherence cannot be predicted realistically. Special emphasis has been placed on the effect of line average along the beam. One section has been devoted to the effect of spectral aliasing, which may cause severe problems in the interpretation of measured data. This work is considered the theoretical background for the understanding of the coherences calculated on basis of real date. (Author)

  4. All semiconductor laser Doppler anemometer at 1.55 μm

    DEFF Research Database (Denmark)

    Hansen, Rene Skov; Pedersen, Christian

    2008-01-01

    We report to our best knowledge the first all semiconductor Laser Doppler Anemometer (LIDAR) for wind speed determination. We will present the design and first experimental results on a focusing coherent cw laser Doppler anemometer for measuring atmospheric wind velocities in the 10 meters to 300...

  5. Simulation and measurement of the stationary and transient characteristics of the hot sphere anemometer

    NARCIS (Netherlands)

    Loomans, M.G.L.C.; Schijndel, A.W.M. van

    2002-01-01

    The omni-directional hot sphere anemometer, that applies a separate reference point for the temperature correction, currently is the most practical device that is used for the measurement of indoor air flows. The anemometer has been investigated, experimentally and numerically, with regard to statio

  6. Experimental investigations of a sphere anemometer: Wind tunnel and field tests

    Science.gov (United States)

    Heisselmann, Hendrik; Peinke, Joachim; Hoelling, Michael

    2013-11-01

    In our contribution we will compare the sphere anemometer and two standard sensors for wind energy and meteorology based on results from laboratory and atmospheric measurements. The sphere anemometer is a drag-based sensor for simultaneous wind speed and direction measurements. The new anemometer makes use of the velocity-dependent deflection of a lightweight sphere mounted on top of a flexible tube. The deflection of the sphere is detected by means of a highly sensitive light pointer, as used in atomic force microscopy. This allows for the detection of very small displacements and thus enables a high sensor resolution. In wind tunnel experiments the sphere anemometer, a 3D sonic anemometer and a standard cup anemometer were exposed to a turbulent wind field generated with a so-called active grid. All acquired data was compared to those of a highly resolving hot-wire probe. Moreover, the sphere anemometer and the two reference sensors were installed on two near-shore sites in the German Wadden Sea. Several month of data from these campaigns were analyzed regarding wind speed and direction measurements as well as durability and stability of the new anemometer. The presented work was founded by the German Ministry of the Environment, Nature Conservation and Nuclear Safety.

  7. Comparing the sphere anemometer to standard sensors for 2D wind measurements

    Science.gov (United States)

    Heisselmann, Hendrik; Hoelling, Michael; Peinke, Joachim

    2011-11-01

    The cup anemometers commonly used for wind energy applications are fairly robust, but suffer from several drawbacks like their limited temporal resolution, a systematic overestimation of the wind speed in turbulent flows and the inability to measure the wind direction. While sonic anemometers can measure the wind vector at a higher temporal resolution, they are more fragile and significantly more expensive. Therefore, we propose the sphere anemometer as a robust and highly-resolving alternative to standard anemometers. Designed without wearing parts, the sphere anemometer provides simultaneous wind speed and direction measurements as needed for wind turbine operation especially under challenging conditions such as offshore installation. In our contribution, we introduce the setup of the sphere anemometer which is based on the velocity-dependent deflection of a flexible tube with a sphere mounted atop. The deflection is measured in two dimensions using a light pointer, which allows for the simultaneous determination of wind speed and direction via calibration. Experimental results from wind tunnel measurements with sonic anemometer and sphere anemometer are presented, as well as first comparative measurements from the operation on the nacelle of a near-shore wind turbine.

  8. Construction and experimental testing of the constant-bandwidth constant-temperature anemometer.

    Science.gov (United States)

    Ligeza, P

    2008-09-01

    A classical constant-temperature hot-wire anemometer enables the measurement of fast-changing flow velocity fluctuations, although its transmission bandwidth is a function of measured velocity. This may be a source of significant dynamic errors. Incorporation of an adaptive controller into the constant-temperature system results in hot-wire anemometer operating with a constant transmission bandwidth. The construction together with the results of experimental testing of a constant-bandwidth hot-wire anemometer prototype are presented in this article. During the testing, an approximately constant transmission bandwidth of the anemometer was achieved. The constant-bandwidth hot-wire anemometer can be used in measurements of high-frequency variable flows characterized by a wide range of velocity changes.

  9. Fiber-Optic Anemometer Based on Silicon Fabry-Perot Interferometer

    Science.gov (United States)

    2015-11-05

    f, oo •• " • ~ OII Ct’ THIS f’ORM CANCELS AND SUPERSEOES All. P~EVIOUS \\I!:RSI Fiber-optic anemometer based on silicon Fabry-Pérot...monitoring, etc. In this paper, we propose a new anemometer which consists of a Fabry-Pérot interferometer (FPI) implemented using a thin silicon mounted...on the tip of an optical fiber. The anemometer takes advantage of the superior thermal and optical properties of silicon. Silicon is transparent to

  10. Deviation of Cup and Propeller Anemometer Calibration Results with Air Density

    Directory of Open Access Journals (Sweden)

    Santiago Pindado

    2012-03-01

    Full Text Available The effect of air density variations on the calibration constants of several models of anemometers has been analyzed. The analysis was based on a series of calibrations between March 2003 and February 2011. Results indicate a linear behavior of both calibration constants with the air density. The effect of changes in air density on the measured wind speed by an anemometer was also studied. The results suggest that there can be an important deviation of the measured wind speed with changes in air density from the one at which the anemometer was calibrated, and therefore the need to take this effect into account when calculating wind power estimations.

  11. Direct measurement of the spectral transfer function of a laser based anemometer

    DEFF Research Database (Denmark)

    Angelou, Nikolas; Mann, Jakob; Sjöholm, Mikael

    2012-01-01

    The effect of a continuous-wave (cw) laser based anemometer's probe volume on the measurement of wind turbulence is studied in this paper. Wind speed time series acquired by both a remote sensing cw laser anemometer, whose line-of-sight was aligned with the wind direction, and by a reference sensor...... (sonic anemometer) located in the same direction, were used. The spectral transfer function, which describes the attenuation of the power spectral density of the wind speed turbulence, was calculated and found to be in good agreement with the theoretical exponential function, which is based...

  12. Calibration of Hot Wire Anemometers. (Latest Citations from the Aerospace Database)

    Science.gov (United States)

    1996-01-01

    The bibliography contains citations concerning calibration methods and measurement correction schemes for hot wire anemometers. Coverage includes static and dynamic calibration of sensors having single, multiple, cross, and ring wire configurations. Correction methods to account for yaw angle, low-velocity flow, microgravity, wall proximity, and highly fluctuating turbulence, velocity, or temperature are covered. Correction methods are also referenced for installations having multiple sensors. Hot film and laser anemometers, and the use of anemometers in specific industrial and aerospace applications are extensively covered in separate biblographies. (Contains 50-250 citations and includes a subject term index and title list.)

  13. Effects of turbulence and flow inclination on the performance of cup anemometers in the field

    DEFF Research Database (Denmark)

    Papadopoulos, K.H.; Stefantos, N.C.; Schmidt Paulsen, U.;

    2001-01-01

    -dimensional turbulent wind field proved successful in explaining the observed differences. Additional measurements were taken with the anemometers tilted at known angles into and out of the incident wind flow. Thus, a field-derived angular response curve is constructed for each anemometer and the deviations from...... to correct the 10-min mean wind speed. The necessary information for the correction is the turbulent intensity (preferably in the vertical direction) and the mean flow inclination. For demanding applications, the angular response parameters of cup anemometers should be taken into account. The incorporation...

  14. Laser Doppler anemometer studies in unsteady ventricular flows.

    Science.gov (United States)

    Phillips, W M; Furkay, S S; Pierce, W S

    1979-01-01

    The laser Doppler technique was employed to obtain intraventricular velocity distributions on the basis of in vivo confirmation of previous in vitro flow visualization predictions. The quasi-steady assumption required for quantification of flow visualization results is unsatisfactory in regions of high acceleration and fluctuating velocities are unavailable via such techniques. Mean and fluctuating velocity profiles were obtained in a pneumatically driven prosthetic ventricle with the laser Doppler anemometer and stress levels estimated. The preliminary data presented here illustrates that the technique can be applied to such flows. The measurement and data reduction schemes are applicable to a wide range of simulated cardiovascular flows. The particular application to prosthetic ventricle design should minimize the number of in vivo experiments required to develop a satisfactory blood pump and aid in tailoring pump actuation protocols for minimum thromboembolic complications.

  15. Laser anemometer signals: visibility characteristics and application to particle sizing.

    Science.gov (United States)

    Adrian, R J; Orloff, K L

    1977-03-01

    The signal visibility characteristics of a dual beam laser anemometer operated in a backscatter mode have been investigated both experimentally and analytically. The analysis is based on Mie's electromagnetic scattering theory for spherical particles and is exact within the limitations of the scattering theory. It is shown that the signal visibility is a function of the ratio of the particle diameter to the fringe spacing in a certain, restricted case; but more generally it also depends on the Mie scattering size parameter, refractive index, the illuminating beam polarization, and the size, shape, and location of the light collecting aperture. The character of backscatter signal visibility differs significantly from the forward scatter case, and it is concluded that backscatter measurements of particle diameters using the visibility sizing technique may not always be possible. Restrictions on the forward scatter application of the visibility sizing method are also discussed.

  16. Response of phase Doppler anemometer systems to nonspherical droplets.

    Science.gov (United States)

    Damaschke, N; Gouesbet, G; Gréhan, G; Mignon, H; Tropea, C

    1998-04-01

    The Phase Doppler Anemometer (PDA) technique measures particle diameter assuming sphericity. A means for detecting nonsphericity has usually been implemented in commercial PDA systems to avoid sizing errors if the sphericity assumption is not valid. In the present research the response of standard and planar PDA systems is examined experimentally in more detail by passing nonspherical droplets of known shape through the measurement volume. The effectiveness of nonsphericity detection schemes can be evaluated, and furthermore the influence of the droplet oscillations on the frequency and phase evolution of individual signals can be quantified. The light scattering from such particles has been simulated by using geometric optics, and the computed response of standard and planar PDA systems agrees well with the experimental observations. We conclude with some remarks concerning the possibilities of characterizing the nonsphericity with PDA systems.

  17. Measurements of enlarged blood pump models using Laser Doppler Anemometer.

    Science.gov (United States)

    Chua, L P; Yu, S C; Leo, H L

    2000-01-01

    In an earlier study (Chua et al., 1998, 1999a), a 5:1 enlarged model of the Kyoto-NTN Magnetically Suspended Centrifugal Blood Pump (Akamatsu et al., 1995) with five different impeller blade profiles was designed and constructed. Their respective flow characteristics with respect to (1) the three different blade profile designs: forward, radial, and backward, (2) the number of blades used, and (3) the rotating speed were investigated. Among the five impeller designs, the results obtained suggested that impellers A and C designs should be adopted if higher head is required. Impellers A and C therefore were selected for the flow in between their blades to be measured using Laser Doppler Anemometer (LDA), so as to have a better understanding of the flow physics with respect to the design parameters.

  18. An Auto-Associative Residual Processing and K-means Clustering Approach for Anemometer Health Assessment

    Directory of Open Access Journals (Sweden)

    David Siegel

    2011-01-01

    Full Text Available This paper presents a health assessment methodology, as well as specific residual processing and figure of merit algorithms for anemometers in two different configurations. The methodology and algorithms are applied to data sets provided by the Prognostics and Health Management Society 2011 Data Challenge. The two configurations consist of the “paired” data set in which two anemometers are positioned at the same height, and the “shear” data set which includes an array of anemometers at different heights. Various wind speed statistics, wind direction, and ambient temperature information are provided, in which the objective is to classify the anemometer health status during a set of samples from a 5 day period. The proposed health assessment methodology consists of a set of data processing steps that include: data filtering and pre-processing, a residual or difference calculation, and a k-means clustering based figure of merit calculation. The residual processing for the paired data set was performed using a straightforward difference calculation, while the shear data set utilized an additional set of algorithm processing steps to calculate a weighted residual value for each anemometer. The residual processing algorithm for the shear data set used a set of auto-associative neural network models to learn the underlying correlation relationship between the anemometer sensors and to calculate a weighted residual value for each of the anemometer wind speed measurements. A figure of merit value based on the mean value of the smaller of the two clusters for the wind speed residual is used to determine the health status of each anemometer. Overall, the proposed methodology and algorithms show promise, in that the results from this approach resulted in the top score for the PHM 2011 Data Challenge Competition. Using different clustering algorithms or density estimation methods for the figure of merit calculation is being considered for future work.

  19. Zoom lens compensator for a cylindrical window in laser anemometer uses.

    Science.gov (United States)

    Wernet, M P; Seasholtz, R G

    1987-11-01

    In laser anemometer systems, the flow fields under study are typically enclosed by a window. Aberration of a flat window can be corrected by a shift of the object distance. A zooming correction lens eliminates the astigmatism caused by a thick cylindrical window and yields diffraction-limited performance for a monochromatic laser anemometer system. The effects of residual anamorphic distortion are discussed, and procedures for correcting these effects are presented.

  20. Which are more accurate, orthogonal or non-orthogonal sonic anemometers?

    Science.gov (United States)

    Massman, W. J.; Frank, J. M.; Swiatek, E.; Zimmerman, H.; Ewers, B. E.

    2013-12-01

    Sonic anemometry is fundamental to all eddy-covariance studies of surface energy, ecosystem carbon, and water balance. Recent studies have shown the potential underestimation of the vertical wind fluctuations among the most commonly encountered anemometer models, but thus far testing has been focused on non-orthogonal sonic anemometer designs. We hypothesize that these underestimates are systematic to the non-orthogonal design and not attributable to a single manufacturer. If so, orthogonal measurements of vertical wind should be more accurate. We tested this by conducting an experiment to measure the relative consistency between vertical and horizontal wind measurements for three sonic anemometer designs: orthogonal, non-orthogonal, and quasi-orthogonal. Both the orthogonal and non-orthogonal models were from a single manufacturer (K-probe and A-probe, Applied Technologies, Inc.) while the quasi-orthogonal design featured non-orthogonal u- and v-axes but with an orthogonal w-axis (CSAT3V, Campbell Scientific, Inc.). We conducted a 12-week experiment, testing four sonic anemometers relative to a control (CSAT3, Campbell Scientific, Inc.), each week randomly selecting at least one of each model from a pool of twelve instruments (three of each model) and randomly locating the test anemometers around the control. Half-way through the week the test anemometers were re-mounted in a horizontal position. Work was done at the GLEES AmeriFlux site (southeastern Wyoming, USA) which experiences large, uni-directional wind and turbulence. Results are discussed.

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

    Science.gov (United States)

    Yahaya, S.; Frangi, J.

    2004-10-01

    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).

  2. The Cup Anemometer, a Fundamental Meteorological Instrument for the Wind Energy Industry. Research at the IDR/UPM Institute

    OpenAIRE

    Santiago Pindado; Javier Cubas; Félix Sorribes-Palmer

    2014-01-01

    The results of several research campaigns investigating cup anemometer performance carried out since 2008 at the IDR/UPM Institute are included in the present paper. Several analysis of large series of calibrations were done by studying the effect of the rotor’s geometry, climatic conditions during calibration, and anemometers’ ageing. More specific testing campaigns were done regarding the cup anemometer rotor aerodynamics, and the anemometer signals. The effect of the rotor’s geometry on th...

  3. On the Use of Hot-Sphere Anemometers in a Highly Transient Flow in a Double-Skin Facade

    DEFF Research Database (Denmark)

    Jensen, Rasmus Lund; Kalyanova, Olena; Hyldgård, Carl-Erik

    2007-01-01

    is highly transient and therefore, the dynamic properties of the hot-sphere anemometer must be investigated. An experimental setup to measure the dynamic property using a jet-wind tunnel and a device for moving the anemometer is described. The experimental setup allows examination of the standard deviation...... measured by the anemometer. Temperature compensation is the working principle of anemometers. The ability to compensate for different temperatures when exposed to solar radiation is investigated in a controlled environment using a powerful lamp as a radiant heat source. In the double-skin façade, both...

  4. The performance of sonic anemometers under foggy conditions - An intercomparision above a Taiwanese mountainous cloud forest

    Science.gov (United States)

    El-Madany, T.; Griessbaum, F.; Maneke, F.; Chu, H.-S.; Wu, C.-C.; Chang, S. C.; Hsia, Y.-J.; Juang, J.-Y.; Klemm, O.

    2010-07-01

    Foggy conditions are a toughness test for anemometers because the transceivers are continuously influenced by the deposition of fog-droplets. During a period of nearly four weeks three sonic anemometers where tested for their performance under foggy conditions. The anemometers were set up on a 24 meter high flux tower in a 14 meter high Chamaecyparis obtusa var. Formosana forest. The test anemometers were a Gill R3-50, a Young 81000V, and a Campbell CSAT3 (equipped with ‘dripping noses’). All anemometers were set up at one level on the highest platform of the tower. The performance was evaluated on the basis of 10 Hz data. The test site is located in the northwest of Taiwan at about 1650 m above sea level. This location is influenced by a steady diurnal wind system of valley winds during daytime and mountain winds during nighttime. The valley winds transport air masses from the coast up to the mountain where they cool down and fog development occurs. Due to this effect the site is highly frequented with fog. Results of this intercomparison will be presented.

  5. Highly resolved measurements of atmospheric turbulence with the new 2d-Atmospheric Laser Cantilever Anemometer

    Science.gov (United States)

    Jeromin, A.; Schaffarczyk, A. P.; Puczylowski, J.; Peinke, J.; Hölling, M.

    2014-12-01

    For the investigation of atmospheric turbulent flows on small scales a new anemometer was developed, the so-called 2d-Atmospheric Laser Cantilever Anemometer (2d-ALCA). It performs highly resolved measurements with a spatial resolution in millimeter range and temporal resolution in kHz range, thus detecting very small turbulent structures. The anemometer is a redesign of the successfully operating 2d-LCA for laboratory application. The new device was designed to withstand hostile operating environments (rain and saline, humid air). In February 2012, the 2d-ALCA was used for the first time in a test field. The device was mounted in about 53 m above ground level on a lattice tower near the German North Sea coast. Wind speed was measured by the 2d-ALCA at 10 kHz sampling rate and by cup anemometers at 1 Hz. The instantaneous wind speed ranged from 8 m/s to 19 m/s at an average turbulence level of about 7 %. Wind field characteristics were analyzed based on cup anemometer as well as 2d-ALCA. The combination of both devices allowed the study of atmospheric turbulence over several magnitudes in turbulent scales.

  6. On the harmonic analysis of cup anemometer rotation speed: A principle to monitor performance and maintenance status of rotating meteorological sensors

    OpenAIRE

    Pindado Carrion, Santiago; Cubas Cano, Javier; Sorribes Palmer, Felix

    2015-01-01

    The calibration results of one anemometer equipped with several rotors, varying their size, were analyzed. In each case, the 30-pulses pert turn output signal of the anemometer was studied using Fourier series decomposition and correlated with the anemometer factor (i.e., the anemometer transfer function). Also, a 3-cup analytical model was correlated to the data resulting from the wind tunnel measurements. Results indicate good correlation between the post-processed output signal and the wor...

  7. Optimization of Single-Sensor Two-State Hot-Wire Anemometer Transmission Bandwidth.

    Science.gov (United States)

    Ligęza, Paweł

    2008-10-28

    Hot-wire anemometric measurements of non-isothermal flows require the use of thermal compensation or correction circuitry. One possible solution is a two-state hot-wire anemometer that uses the cyclically changing heating level of a single sensor. The area in which flow velocity and fluid temperature can be measured is limited by the dimensions of the sensor's active element. The system is designed to measure flows characterized by high velocity and temperature gradients, although its transmission bandwidth is very limited. In this study, we propose a method to optimize the two-state hot-wire anemometer transmission bandwidth. The method is based on the use of a specialized constanttemperature system together with variable dynamic parameters. It is also based on a suitable measurement cycle paradigm. Analysis of the method was undertaken using model testing. Our results reveal a possible significant broadening of the two-state hot-wire anemometer's transmission bandwidth.

  8. Direct measurement of the spectral transfer function of a laser based anemometer.

    Science.gov (United States)

    Angelou, Nikolas; Mann, Jakob; Sjöholm, Mikael; Courtney, Michael

    2012-03-01

    The effect of a continuous-wave (cw) laser based anemometer's probe volume on the measurement of wind turbulence is studied in this paper. Wind speed time series acquired by both a remote sensing cw laser anemometer, whose line-of-sight was aligned with the wind direction, and by a reference sensor (sonic anemometer) located in the same direction, were used. The spectral transfer function, which describes the attenuation of the power spectral density of the wind speed turbulence, was calculated and found to be in good agreement with the theoretical exponential function, which is based on the properties of the probe volume of a focused Gaussian laser beam. Parameters such as fluctuations of the wind direction, as well as the overestimation of the laser Doppler spectrum threshold, were found to affect the calculation of the spectral transfer function by introducing high frequency noise.

  9. Visual modeling of laser Doppler anemometer signals by moiré fringes.

    Science.gov (United States)

    Durst, F; Stevenson, W H

    1976-01-01

    This report describes the employment of moiré patterns to model visually interference phenomena in general and laser Doppler anemometer signals in particular. The modeling includes signals created in dual beam and reference beam anemometers by both single particles and particle pairs. The considerations are extended to visual modeling of multiparticle signals and the decay of signal quality in the presence of many particles. The fringe model of the laser Doppler anemometer is also considered, and moiré patterns are employed to demonstrate the interference fringes in the crossover region of two intersecting laser beams. Gaussian beam properties are taken into account to allow the effects of improperly designed optical systems to be studied. Instructions for using computer generated transparencies to produce the different moiré patterns are provided to allow the reader to study in detail the various interference phenomena described.

  10. Fiber optic anemometer based on metal infiltrated microstructured optical fiber inscribed with Bragg grating

    Science.gov (United States)

    Wang, Jie; Gao, Shaorui; Liu, Zhengyong; Zhang, A. Ping; Shen, Yonghang; Tam, Hwayaw

    2015-09-01

    An all-fiber optical anemometer with high light-heat conversion efficiency by using an in-house microstructured optical fiber Bragg grating (MOFBG) is presented. Low-molten-temperature BiSnIn alloy was successfully infiltrated into 11- cm length of a six-hole microstructured optical fiber which was inscribed with a fibre Bragg grating (FBG) centered at ~848 nm. Light launched into the MOFBG was strongly absorbed by the metal to generate heat, while the FBG was utilized to monitor temperature change due to surrounding wind speed. The sensitivity of the laser-heated MOFBG anemometer was measured to be ~0.1 nm/(m/s) for wind speed ranged from 0.5 m/s to 2 m/s. The efficiency of the anemometer, defined as effective sensitivity per pump power, is 8.7 nm/(m/s*W).

  11. ACCUWIND - Classification of five cup anemometers according to IEC61400-12-1

    Energy Technology Data Exchange (ETDEWEB)

    Friis Pedersen, T.; Dahlberg, J.Aa.; Busche, P.

    2006-05-15

    The characteristics of five cup anemometers were investigated in detail, and data are presented in figures and tables. The characteristics include: normal wind tunnel calibrations; angular response measurements at 5, 8 and 11m/s; torque coefficient curve measurements from combined tilt and ramp-gust tests, torque coefficient curve measurements for non-tilted conditions; rotor inertia measurements and measurements of friction of bearings at temperatures -10 deg. C to 40 deg. C. The characteristics are fitted to two different time domain cup anemometer models, and simulations of the cup anemometers are made with artificial wind generators to make classifications according to annex I and J of the standard IEC 61400-12-1 on power performance measurements. Results of classification are shown in graphs of systematic deviations and class index tables. (au)

  12. Linear Time-Invariant Compensation of Cup Anemometer and Vane Inertia

    Science.gov (United States)

    Hristov, Tihomir S.; Miller, Scott D.; Friehe, Carl A.

    We propose a method to compensate for the phase lag and the amplitudeattenuation in the cup anemometer signal. These two effects, caused by theinstrument's inertia, are the major flaws of the cup anemometer in additionto over-speeding. Since the instrument's response is invariant in wavenumber (not frequency) representation, we transform the signals to becompensated from the time domain to the spatial domain by using Taylor'shypothesis. In the spatial domain we apply a linear time-invariant filterto eliminate the phase lag and the amplitude attenuation. The proposedprocedure improves instrument performance down to spatial scales equal toor smaller than the distance constant of the anemometer. The method for cupanemometer compensation is presented in detail and later adapted for vanes.

  13. Uncertainties in Cup Anemometer Calibrations. Type A and Type B uncertainties

    Energy Technology Data Exchange (ETDEWEB)

    Eecen, P.J. Eecen; De Noord, M. [ECN Wind Energy, Petten (Netherlands)

    2005-06-01

    ECN Wind Energy is accredited according ISO 17025 to perform power performance measurements of wind turbines following IEC 61400-12 and Measnet. The typical results of these measurements are measured power curves of the wind turbines. These curves show the electrical power versus the wind speed. Part of the power performance analysis is the uncertainty analysis. In power performance measurements according IEC 61400-12 or Measnet, the wind speed is measured using cup anemometers. The uncertainty of the wind speed measurements depends among others on the calibration uncertainty. The cup-anemometer calibration uncertainty is divided in Type A and Type B uncertainty. The Type A uncertainty is the statistical uncertainty of the wind speed measurement and can be calculated from the wind speed measurements. The Type B uncertainty includes all uncertainties that do not have a statistical background. For example, these are uncertainties due to temperature changes, air pressure changes, transducer gain influences, and digital conversion influences, etc. This document presents an overview of the type B uncertainties of a cup anemometer calibration following the Measnet 'Cup Anemometer Calibration Procedure, Version 1, September 1997' and the proposal for the IEC 61400-12 that is currently under vote. For the calculations, the numbers applying to the DEWI wind tunnel are used throughout the report. It is shown that the cup anemometer in wind tunnels has unstable behaviour due to the turbulent wakes of the cups. An analysis of uncertainties due to regression in cup anemometer calibrations is presented and compared to the standard uncertainty.

  14. The Cup Anemometer, a Fundamental Meteorological Instrument for the Wind Energy Industry. Research at the IDR/UPM Institute

    Directory of Open Access Journals (Sweden)

    Santiago Pindado

    2014-11-01

    Full Text Available The results of several research campaigns investigating cup anemometer performance carried out since 2008 at the IDR/UPM Institute are included in the present paper. Several analysis of large series of calibrations were done by studying the effect of the rotor’s geometry, climatic conditions during calibration, and anemometers’ ageing. More specific testing campaigns were done regarding the cup anemometer rotor aerodynamics, and the anemometer signals. The effect of the rotor’s geometry on the cup anemometer transfer function has been investigated experimentally and analytically. The analysis of the anemometer’s output signal as a way of monitoring the anemometer status is revealed as a promising procedure for detecting anomalies.

  15. Motion-Corrected 3D Sonic Anemometer for Tethersondes and Other Moving Platforms

    Science.gov (United States)

    Bognar, John

    2012-01-01

    To date, it has not been possible to apply 3D sonic anemometers on tethersondes or similar atmospheric research platforms due to the motion of the supporting platform. A tethersonde module including both a 3D sonic anemometer and associated motion correction sensors has been developed, enabling motion-corrected 3D winds to be measured from a moving platform such as a tethersonde. Blimps and other similar lifting systems are used to support tethersondes meteorological devices that fly on the tether of a blimp or similar platform. To date, tethersondes have been limited to making basic meteorological measurements (pressure, temperature, humidity, and wind speed and direction). The motion of the tethersonde has precluded the addition of 3D sonic anemometers, which can be used for high-speed flux measurements, thereby limiting what has been achieved to date with tethersondes. The tethersonde modules fly on a tether that can be constantly moving and swaying. This would introduce enormous error into the output of an uncorrected 3D sonic anemometer. The motion correction that is required must be implemented in a low-weight, low-cost manner to be suitable for this application. Until now, flux measurements using 3D sonic anemometers could only be made if the 3D sonic anemometer was located on a rigid, fixed platform such as a tower. This limited the areas in which they could be set up and used. The purpose of the innovation was to enable precise 3D wind and flux measurements to be made using tether - sondes. In brief, a 3D accelerometer and a 3D gyroscope were added to a tethersonde module along with a 3D sonic anemometer. This combination allowed for the necessary package motions to be measured, which were then mathematically combined with the measured winds to yield motion-corrected 3D winds. At the time of this reporting, no tethersonde has been able to make any wind measurement other than a basic wind speed and direction measurement. The addition of a 3D sonic

  16. Summary of the steps involved in the calibration of a Spinner anemometer

    DEFF Research Database (Denmark)

    Demurtas, Giorgio; Friis Pedersen, Troels

    The present report is a practical guide that summarizes the steps involved in the calibration of a spinner anemometer. For each step is brie y recalled the objective, which document describes the procedure to use, and what actions must follow the calibration.......The present report is a practical guide that summarizes the steps involved in the calibration of a spinner anemometer. For each step is brie y recalled the objective, which document describes the procedure to use, and what actions must follow the calibration....

  17. Application of the hot-wire anemometer to respiratory measurements in small animal.

    Science.gov (United States)

    Godal, A; Belenky, D A; Standaert, T A; Woodrum, D E; Grimsrud, L; Hodson, W A

    1976-02-01

    A hot-wire anemometer was evaluated to determine its suitability for measurement of small tidal volumes. Used with a constant background flow of gas, the output of the hot-wire anemometer was linear and independent of respiratory frequency, temperature, and humidity. The change in output with CO2 concentration was negligible within the physiologic range. The use of a background flow eliminates the need for one-way valves, minimizes dead space, and maintains the flow velocity past the hot wire within its range of linear response.

  18. Power curve measurement with Spinner Anemometer according to IEC 61400-12-2

    DEFF Research Database (Denmark)

    Demurtas, Giorgio

    of drawbacks that makes use of the standard with respect to nacelle anemometry difficult to apply in the field [3] [4]. An option in the standard is to use spinner anemometry, a type of wind sensor that measures wind speed on the spinner in front of the rotor. The report is based on spinner anemometer...... measurements from two adjacent wind turbines and a met-mast. Due to the site layout, it is possible with the met-mast to measure the power curve of both turbines. The report also presents a method for evaluation of uncertainty related to the spinner anemometer....

  19. Calibration of a spinner anemometer for flow angle measurements by use of wind turbine yawing

    DEFF Research Database (Denmark)

    Demurtas, Giorgio; Friis Pedersen, Troels

    The present report describes a method to calibrate a spinner anemometer ow angle measurements. The turbine is yawed several times (5 times approximately 60 with respect to the wind direction) in steady wind (> 6 m/s) and measurements of yaw position (measured by a yaw position sensor) and yaw...... misalignment (measured by the spinner anemometer under calibration) are recorded. The tangent of the two angles is plotted in a scatter plot. A linear fitting is made, and the slope coefficient is the correction factor Fα. The method applied to a Nordtank 500kW wind turbine erected at the Risø test site...

  20. Time-of-Flight Laser Anemometer for Velocity Measurements in the Atmosphere

    DEFF Research Database (Denmark)

    Lading, Lars; Jensen, A. Skov; Fog, C.

    1978-01-01

    In the system described, a 1W CW Ar II laser operates over a range of 70 m with spatial and temporal resolutions of mm and 10-100 m sec, respectively. Mean wind velocities obtained with a cup-anemometer agree within 10%......In the system described, a 1W CW Ar II laser operates over a range of 70 m with spatial and temporal resolutions of mm and 10-100 m sec, respectively. Mean wind velocities obtained with a cup-anemometer agree within 10%...

  1. Mathematical analysis of the effect of rotor geometry on cup anemometer response.

    Science.gov (United States)

    Sanz-Andrés, Ángel; Pindado, Santiago; Sorribes-Palmer, Félix

    2014-01-01

    The calibration coefficients of two commercial anemometers equipped with different rotors were studied. The rotor cups had the same conical shape, while the size and distance to the rotation axis varied. The analysis was based on the 2-cup positions analytical model, derived using perturbation methods to include second-order effects such as pressure distribution along the rotating cups and friction. The comparison with the experimental data indicates a nonuniform distribution of aerodynamic forces on the rotating cups, with higher forces closer to the rotating axis. The 2-cup analytical model is proven to be accurate enough to study the effect of complex forces on cup anemometer performance.

  2. A laser fluorescence anemometer system for the Langley 16- by 24-inch water tunnel

    Science.gov (United States)

    Owen, F. K.; Orngard, Gary M.; Neuhart, Dan H.

    1991-01-01

    A laser fluorescence anemometer which comprises a three-component laser Doppler velocimeter system with a fourth channel to measure fluorescent dye concentration has been installed in the NASA Langley 16- by 24-in water tunnel. The system includes custom designed optics, data acquisition, and traverse control instruments and a custom software package. Feasibility studies demonstrated how water tunnels can be used in conjunction with advanced optical techniques to provide nonintrusive detailed flow field measurements of complex fluid flows with a minimum of expense. The measurements show that the laser fluorescence anemometer can provide new insight into the structure, entrainment, control and of mixing vortical and shear layer flows.

  3. Dynamic characteristics of a simple constant-temperature hot-wire anemometer.

    Science.gov (United States)

    Lu, S S

    1979-06-01

    A simple constant-temperatue hot-wire anemometer has been analyzed and tested in a shock tube and by electronic tests. In the derivation of the governing equations, the finite open-loop gain of an operational amplifier is considered. The measured values of the natural frequency and the damping coefficient for the anemometer system are in satisfactory agreement with the theory. For short probe cables, the frequency response is found to be limited by the finite open-loop gain of the amplifier.

  4. Fast-Response Fiber-Optic Anemometer with Temperature Self-Compensation

    Science.gov (United States)

    2015-05-18

    6), 7237–7247 (2015). 13. M. N. Özisik, Heat Transfer : A Basic Approach (McGraw-Hill, 1985). 14. M. A. Green, “Self-consistent optical parameters of...type that has been widely investigated and have shown great promise [1–3, 9, 10]. In particular, the laser heated fiber-optic hot- wire anemometers...hot- wire anemometer [9], the heat loss is related to the product of the temperature difference and the square root of wind speed. Therefore, it is a

  5. Directional anemometer based on an anisotropic flat-clad tapered fiber Michelson interferometer

    Science.gov (United States)

    Lee, Cheng-Ling; Lee, Chung-Fen; Li, Chai-Ming; Chiang, Tsai-Ching; Hsiao, Ying-Li

    2012-07-01

    This work demonstrates a sensitive directional anemometer that is based on a pendulum-type of anisotropic flat-clad tapered fiber Michelson interferometer (AFCTFMI). The AFCTFMI is fabricated by tapering an anisotropic flat-cladding fiber to establish structural anisotropy, and enables the sensing of the direction and magnitude of flowing air (wind). Wavelength shifts and fringes visibility of the measured interference fringes are correlated with the magnitude and furthermore the direction of the wind. Experimental results agree closely with the theoretical analysis. The directional anemometer can simultaneously and effectively indicate the direction, and sensitively measure the magnitude of wind.

  6. A Phase-Locked Loop Continuous Wave Sonic Anemometer-Thermometer

    DEFF Research Database (Denmark)

    Larsen, Søren Ejling; Weller, F. W.; Busings, J. A.

    1979-01-01

    A continuous wake sonic anemometer-thermometer has been developed for simultaneous measurements of vertical velocity and temperature. The phase angle fluctuations are detected by means of a monolithic integrated phase-locked loop, the latter feature providing for inexpensive and accurate electron......A continuous wake sonic anemometer-thermometer has been developed for simultaneous measurements of vertical velocity and temperature. The phase angle fluctuations are detected by means of a monolithic integrated phase-locked loop, the latter feature providing for inexpensive and accurate...

  7. Mathematical Analysis of the Effect of Rotor Geometry on Cup Anemometer Response

    Directory of Open Access Journals (Sweden)

    Ángel Sanz-Andrés

    2014-01-01

    Full Text Available The calibration coefficients of two commercial anemometers equipped with different rotors were studied. The rotor cups had the same conical shape, while the size and distance to the rotation axis varied. The analysis was based on the 2-cup positions analytical model, derived using perturbation methods to include second-order effects such as pressure distribution along the rotating cups and friction. The comparison with the experimental data indicates a nonuniform distribution of aerodynamic forces on the rotating cups, with higher forces closer to the rotating axis. The 2-cup analytical model is proven to be accurate enough to study the effect of complex forces on cup anemometer performance.

  8. 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...

  9. Eddy-correlation measurements above a maize crop using a simple cruciform hot-wire anemometer

    NARCIS (Netherlands)

    Bottemanne, F.A.

    1979-01-01

    For measurements of the vertical transport of heat and momentum in the turbulent and slightly unstable boundary layer above a maize crop eddy-correlation techniques were applied. In addition to a vertical Gill-propellor anemometer and a Gill-propellor bivane, a cruciform hot-wire probe, mounted on a

  10. All-optical fiber anemometer based on laser heated fiber Bragg gratings.

    Science.gov (United States)

    Gao, Shaorui; Zhang, A Ping; Tam, Hwa-Yaw; Cho, L H; Lu, Chao

    2011-05-23

    A fiber-optic anemometer based on fiber Bragg gratings (FBGs) is presented. A short section of cobalt-doped fiber was utilized to make a fiber-based "hot wire" for wind speed measurement. Fiber Bragg gratings (FBGs) were fabricated in the cobalt-doped fiber using 193 nm laser pulses to serve as localized temperature sensors. A miniature all-optical fiber anemometer is constructed by using two FBGs to determine the dynamic thermal equilibrium between the laser heating and air flow cooling through monitoring the FBGs' central wavelengths. It was demonstrated that the sensitivity of the sensor can be adjusted through the power of pump laser or the coating on the FBG. Experimental results reveal that the proposed FBG-based anemometer exhibits very good performance for wind speed measurement. The resolution of the FBG-based anemometer is about 0.012 m/s for wind speed range between 2.0 m/s and 8.0 m/s.

  11. MEASUREMENT OF MOTION CORRECTED WIND VELOCITY USING AN AEROSTAT LOFTED SONIC ANEMOMETER

    Science.gov (United States)

    An aerostat-lofted, sonic anemometer was used to determine instantaneous 3 dimensional wind velocities at altitudes relevant to fire plume dispersion modeling. An integrated GPS, inertial measurement unit, and attitude heading and reference system corrected the wind data for th...

  12. A Raman anemometer for component-selective velocity measurements of particles in a flow

    NARCIS (Netherlands)

    Florisson, O.; Mul, de F.F.M.; Winter, de H.G.

    1981-01-01

    An anemometer for the measurement of the velocity of particles of different components in a flow, separate and apart from that of the flow itself, is described. As a component-selective mechanism Raman scattering is used. The velocity is measured by relating the autocorrelated scattering signal to t

  13. Determining the Velocity Fine Structure by a Laser Anemometer in VAD operation

    DEFF Research Database (Denmark)

    Kristensen, Leif; Kirkegaard, Peter; Mikkelsen, Torben

    The theoretical basis for determining the dissipation ε, by measuring the velocity structure function with a CW-laser anemometer has been derived in the case of calm wind conditions. If there is a well defined mean wind speed the structure function can be obtained by having the laser beam pointing...

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

    DEFF Research Database (Denmark)

    Mann, Jakob; Cariou, Jean-Pierre; Courtney, Michael

    2009-01-01

    to a 3D sonic anemometer mounted at 78 m above the ground. The results show generally very good correlation between the lidar and the sonic times series, except that the variance of the velocity measured by the lidar is attenuated due to spatial filtering. The amount of attenuation can however...

  15. Four-Spot Time-Of-Flight Laser Anemometer For Turbomachinery

    Science.gov (United States)

    Wernet, Mark P.; Skoch, Gary J.

    1995-01-01

    Two-color, four-spot time-of-flight laser anemometer designed for measuring flow velocity within narrow confines of small centrifugal compressor. Apparatus well suited for measuring fast (typical speeds 160 to 700 m/s), highly turbulent gas flows in turbomachinery. Other potential applications include measurement of gas flows in pipelines and in flows from explosions.

  16. A digital technique for linearising the output of a turbine anemometer.

    Science.gov (United States)

    Crane, R A; Stuttard, B

    1976-01-01

    A technique is described by which it is possible, using digital integrated circuits, to linearise the output of transducers which produce their output in serial digital form. The linearisation technique is used to improve the performance of an anemometer used in the measurement of pulmonary function. The new technique makes possible accurate paediatric measurements using transducers previously intended for adults.

  17. Broadening of the Measured Frequency Spectrum in a Differential Laser Anemometer due to Interference Plane Gradients

    DEFF Research Database (Denmark)

    Hanson, Steen Grüner

    1973-01-01

    It is shown how an inaccurate alignment of a differential laser anemometer may cause a significant broadening of the Doppler spectrum. The reason is the appearance of gradients in the interference pattern in the measuring volume. The phenomenon was investigated theoretically, and a method...

  18. 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 dev...

  19. A new anemometer for 2D atmospheric flow measurements in rough environments

    Science.gov (United States)

    Heisselmann, Hendrik; Hoelling, Michael; Peinke, Joachim

    2010-11-01

    One major downside of cup anemometry is the different response time for increasing and decreasing wind speeds, causing a systematic over-estimation of the mean wind speed under turbulent conditions. Especially under harsh environmental conditions like in offshore operation, the measuring principle leads to a wear of bearings causing a de-calibration over time and the requirement of regular maintenance. Therefore, we propose the newly developed sphere anemometer as a simple and robust alternative without any moving parts. The sphere anemometer consists of a flexible tube with a sphere mounted on top of it. The drag force acting on the sphere and its support causes a deflection, which is measured by means of a light pointer. Via calibration, this allows for simultaneous determination of wind speed and direction using only one sensor. In our contribution, we introduce the anemometer's setup and it's optimization towards offshore application. Additionally, experimental results obtained from wind tunnel measurements of turbulent flows are presented. Measurements under real wind conditions are compared to those of state-of-the-art wind speed sensors, such as cup and ultrasonic anemometers.

  20. Final report on EURAMET project No. 827: LDA-based intercomparison of anemometers

    Science.gov (United States)

    Müller, Harald

    2013-01-01

    A regional air speed comparison between six EURAMET laboratories used an ultrasonic anemometer and a laser Doppler anemometer (LDA) at air speeds between 0.2 m s-1 and 40 m s-1. Based on periodic calibrations at the pilot laboratory (PTB), the uncertainty contributed to the comparison by the LDA was 0.2% and the uncertainty contributed by the ultrasonic anemometer depended on the air speed and varied between 2.95% and 0.11%. The degrees of equivalence between the participants were notably better for the laser Doppler anemometer data than for the ultrasonic anemometer data. For example, using the 95% chi-squared consistency check, 16 of the original 59 participant data points were removed as discrepant from the ultrasonic data set, but only one point was discrepant in the LDA data. A possible explanation is that the LDA is non-intrusive and therefore does not alter the velocity field in the wind tunnel whereas the ultrasonic device does produce blockage effects. The results of this comparison (and prior EURAMET and CIPM comparisons) indicate a need for more attention to blockage effects during air speed calibrations and their effect on air speed uncertainty statements. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by EURAMET, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  1. Identification of tower-wake distortions using sonic anemometer and lidar measurements

    Science.gov (United States)

    McCaffrey, Katherine; Quelet, Paul T.; Choukulkar, Aditya; Wilczak, James M.; Wolfe, Daniel E.; Oncley, Steven P.; Brewer, W. Alan; Debnath, Mithu; Ashton, Ryan; Valerio Iungo, G.; Lundquist, Julie K.

    2017-02-01

    The eXperimental Planetary boundary layer Instrumentation Assessment (XPIA) field campaign took place in March through May 2015 at the Boulder Atmospheric Observatory, utilizing its 300 m meteorological tower, instrumented with two sonic anemometers mounted on opposite sides of the tower at six heights. This allowed for at least one sonic anemometer at each level to be upstream of the tower at all times and for identification of the times when a sonic anemometer is in the wake of the tower frame. Other instrumentation, including profiling and scanning lidars aided in the identification of the tower wake. Here we compare pairs of sonic anemometers at the same heights to identify the range of directions that are affected by the tower for each of the opposing booms. The mean velocity and turbulent kinetic energy are used to quantify the wake impact on these first- and second-order wind measurements, showing up to a 50 % reduction in wind speed and an order of magnitude increase in turbulent kinetic energy. Comparisons of wind speeds from profiling and scanning lidars confirmed the extent of the tower wake, with the same reduction in wind speed observed in the tower wake, and a speed-up effect around the wake boundaries. Wind direction differences between pairs of sonic anemometers and between sonic anemometers and lidars can also be significant, as the flow is deflected by the tower structure. Comparisons of lengths of averaging intervals showed a decrease in wind speed deficit with longer averages, but the flow deflection remains constant over longer averages. Furthermore, asymmetry exists in the tower effects due to the geometry and placement of the booms on the triangular tower. An analysis of the percentage of observations in the wake that must be removed from 2 min mean wind speed and 20 min turbulent values showed that removing even small portions of the time interval due to wakes impacts these two quantities. However, a vast majority of intervals have no

  2. Identification of tower-wake distortions using sonic anemometer and lidar measurements

    Energy Technology Data Exchange (ETDEWEB)

    McCaffrey, Katherine; Quelet, Paul T.; Choukulkar, Aditya; Wilczak, James M.; Wolfe, Daniel E.; Oncley, Steven P.; Brewer, W. Alan; Debnath, Mithu; Ashton, Ryan; Iungo, G. Valerio; Lundquist, Julie K.

    2017-02-02

    The eXperimental Planetary boundary layer Instrumentation Assessment (XPIA) field campaign took place in March through May 2015 at the Boulder Atmospheric Observatory, utilizing its 300 m meteorological tower, instrumented with two sonic anemometers mounted on opposite sides of the tower at six heights. This allowed for at least one sonic anemometer at each level to be upstream of the tower at all times and for identification of the times when a sonic anemometer is in the wake of the tower frame. Other instrumentation, including profiling and scanning lidars aided in the identification of the tower wake. Here we compare pairs of sonic anemometers at the same heights to identify the range of directions that are affected by the tower for each of the opposing booms. The mean velocity and turbulent kinetic energy are used to quantify the wake impact on these first- and second-order wind measurements, showing up to a 50 % reduction in wind speed and an order of magnitude increase in turbulent kinetic energy. Comparisons of wind speeds from profiling and scanning lidars confirmed the extent of the tower wake, with the same reduction in wind speed observed in the tower wake, and a speed-up effect around the wake boundaries. Wind direction differences between pairs of sonic anemometers and between sonic anemometers and lidars can also be significant, as the flow is deflected by the tower structure. Comparisons of lengths of averaging intervals showed a decrease in wind speed deficit with longer averages, but the flow deflection remains constant over longer averages. Furthermore, asymmetry exists in the tower effects due to the geometry and placement of the booms on the triangular tower. An analysis of the percentage of observations in the wake that must be removed from 2 min mean wind speed and 20 min turbulent values showed that removing even small portions of the time interval due to wakes impacts these two quantities. However, a vast majority of intervals have no

  3. Laser Anemometer Measurements of the Three-Dimensional Rotor Flow Field in the NASA Low-Speed Centrifugal Compressor

    Science.gov (United States)

    Hathaway, Michael D.; Chriss, Randall M.; Strazisar, Anthony J.; Wood, Jerry R.

    1995-01-01

    A laser anemometer system was used to provide detailed surveys of the three-dimensional velocity field within the NASA low-speed centrifugal impeller operating with a vaneless diffuser. Both laser anemometer and aerodynamic performance data were acquired at the design flow rate and at a lower flow rate. Floor path coordinates, detailed blade geometry, and pneumatic probe survey results are presented in tabular form. The laser anemometer data are presented in the form of pitchwise distributions of axial, radial, and relative tangential velocity on blade-to-blade stream surfaces at 5-percent-of-span increments, starting at 95-percent-of-span from the hub. The laser anemometer data are also presented as contour and wire-frame plots of throughflow velocity and vector plots of secondary velocities at all measurement stations through the impeller.

  4. Optimization of fringe-type laser anemometers for turbine engine component testing

    Science.gov (United States)

    Seasholtz, R. G.; Oberle, L. G.; Weikle, D. H.

    1984-01-01

    The fringe type laser anemometer is analyzed using the Cramer-Rao bound for the variance of the estimate of the Doppler frequency as a figure of merit. Mie scattering theory is used to calculate the Doppler signal wherein both the amplitude and phase of the scattered light are taken into account. The noise from wall scatter is calculated using the wall bidirectional reflectivity and the irradiance of the incident beams. A procedure is described to determine the optimum aperture mask for the probe volume located a given distance from a wall. The expected performance of counter type processors is also discussed in relation to the Cramer-Rao bound. Numerical examples are presented for a coaxial backscatter anemometer. Previously announced in STAR as N84-25019

  5. Silicon Carbide High Temperature Anemometer and Method for Assembling the Same

    Science.gov (United States)

    Okojie, Robert S. (Inventor); Fralick, Gustave C. (Inventor); Saad, George J. (Inventor)

    2003-01-01

    A high temperature anemometer includes a pair of substrates. One of the substrates has a plurality of electrodes on a facing surface, while the other of the substrates has a sensor cavity on a facing surface. A sensor is received in the sensor cavity, wherein the sensor has a plurality of bondpads, and wherein the bond pads contact the plurality of electrodes when the facing surfaces are mated with one another. The anemometer further includes a plurality of plug-in pins, wherein the substrate with the cavity has a plurality of trenches with each one receiving a plurality of plug-in pins. The plurality of plug-in pins contact the plurality of electrodes when the substrates are mated with one another. The sensor cavity is at an end of one of the substrates such that the sensor partially extends from the substrate. The sensor and the substrates are preferably made of silicon carbide.

  6. Assessment of wind conditions at a fjord inlet by complementary use of sonic anemometers and lidars

    DEFF Research Database (Denmark)

    Jakobsen, Jasna Bogunovic; Cheynet, Etienne; Snæbjörnsson, Jonas

    2015-01-01

    Wind velocity measurement devices based on the remote optical sensing, lidars, are extensively applied in wind energy research and wind farm operation. The present paper demonstrates the relevance and potential of lidar measurements for other windsensitive structures such as long-span bridges....... In a pilot study in Lysefjord, Norway, a pulsed long-range lidar and two short-range WindScanners were installed at the bridge site, together with a long-term monitoring system based on sonic anemometers. The deployment of the two types of lidars is described in more details and the complementary value...... of the data from all three types of the instruments is illustrated. The emphasis is on the lidars’ potential to map the wind conditions along the whole span of a bridge in a complex terrain, as opposed to ”point” measurements achievable by sonic anemometers. The challenging balance between the spatial...

  7. Comparison of surface wind stress measurements - Airborne radar scatterometer versus sonic anemometer

    Science.gov (United States)

    Brucks, J. T.; Leming, T. D.; Jones, W. L.

    1980-01-01

    Sea surface wind stress measurements recorded by a sonic anemometer are correlated with airborne scatterometer measurements of ocean roughness (cross section of radar backscatter) to establish the accuracy of remotely sensed data and assist in the definition of geophysical algorithms for the scatterometer sensor aboard Seasat A. Results of this investigation are as follows: Comparison of scatterometer and sonic anemometer wind stress measurements are good for the majority of cases; however, a tendency exists for scatterometer wind stress to be somewhat high for higher wind conditions experienced in this experiment (6-9 m/s). The scatterometer wind speed algorithm tends to overcompute the higher wind speeds by approximately 0.5 m/s. This is a direct result of the scatterometer overestimate of wind stress from which wind speeds are derived. Algorithmic derivations of wind speed and direction are, in most comparisons, within accuracies defined by Seasat A scatterometer sensor specifications.

  8. Nasal airflow measurement using a compensated thermistor anemometer. Part 2. Computer signal processing and quantitative analysis.

    Science.gov (United States)

    Besar, S S; Kelly, S W; Manley, M C

    1990-03-01

    A nasal anemometer is a useful tool for speech therapists in their assessment of treatment effectiveness. This work is the second part of a research scheme which describes how the system is compatible with the use of an IBM PC-AT microcomputer using a suitable analogue-to-digital convertor. This enables the system to perform signal processing and to display, draw, and calculate a numerical 'figure of merit' using Kendall's tau nonparametric correlation.

  9. Laser transit anemometer measurements of a JANNAF nozzle base velocity flow field

    Science.gov (United States)

    Hunter, William W., Jr.; Russ, C. E., Jr.; Clemmons, J. I., Jr.

    1990-01-01

    Velocity flow fields of a nozzle jet exhausting into a supersonic flow were surveyed. The measurements were obtained with a laser transit anemometer (LTA) system in the time domain with a correlation instrument. The LTA data is transformed into the velocity domain to remove the error that occurs when the data is analyzed in the time domain. The final data is shown in velocity vector plots for positions upstream, downstream, and in the exhaust plane of the jet nozzle.

  10. Implementation of a new type of time-of-flight laser anemometer.

    Science.gov (United States)

    Wernet, M P; Edwards, R V

    1986-03-01

    A new time-of-flight (TOF) laser anemometer system utilizing a spatial lead-lag filter for bipolar pulse generation has been constructed and tested. This new TOF has been modified to enable measurements in turbulent flows near walls. Good results have been obtained as close as 100 microm from a surface, with a 140-mm focal length final lens. Lading's theory for the behavior of the measurement variance has been confirmed for this configuration.

  11. Airflow study of pathologic larynges using a constant temperature anemometer: further experience.

    Science.gov (United States)

    Kitajima, K; Fujita, F

    1992-08-01

    Phonatory airflow was recorded in 361 laryngeal disease patients and 59 normal subjects by using a constant temperature anemometer to measure Isshiki's proposed parameter, the AC/DC percentage. The pathologic groups displayed AC/DC percentage values smaller than those of the normal group. The value differentials observed among the various diseases suggest that the AC/DC percentage may reflect the vibrational capacity of the vocal cords.

  12. Turbulence fluxes and variances measured with a sonic anemometer mounted on a tethered balloon

    OpenAIRE

    Canut, Guylaine; Couvreux, Fleur; Lothon, Marie; Legain, Dominique; Piguet, Bruno; Lampert, Astrid; Maurel, William; Moulin, Eric

    2016-01-01

    This study presents the first deployment in field campaigns of a balloon-borne turbulence probe, developed with a sonic anemometer and an inertial motion sensor suspended below a tethered balloon. This system measures temperature and horizontal and vertical wind at high frequency and allows the estimation of heat and momentum fluxes as well as turbulent kinetic energy in the lower part of the boundary layer. The system was validated during three field experiments with differ...

  13. Mathematical Analysis of the Effect of Rotor Geometry on Cup Anemometer Response

    OpenAIRE

    Ángel Sanz-Andrés; Santiago Pindado; Félix Sorribes-Palmer

    2014-01-01

    The calibration coefficients of two commercial anemometers equipped with different rotors were studied. The rotor cups had the same conical shape, while the size and distance to the rotation axis varied. The analysis was based on the 2-cup positions analytical model, derived using perturbation methods to include second-order effects such as pressure distribution along the rotating cups and friction. The comparison with the experimental data indicates a nonuniform distribution of aerodynamic f...

  14. A high-performance constant-temperature hot-wire anemometer

    Science.gov (United States)

    Watmuff, Jonathan H.

    1994-01-01

    A high-performance constant-temperature hot-wire anemometer has been designed based on a system theory analysis that can be extended to arbitrary order. A motivating factor behind the design was to achieve the highest possible frequency response while ensuring overall system stability. Based on these considerations, the design of the circuit and the selection of components is discussed in depth. Basic operating instructions are included in an operator's guide. The analysis is used to identify operating modes, observed in all anemometers, that are misleading in the sense that the operator can be deceived by interpreting an erroneous frequency response. Unlike other anemometers, this instrument provides front panel access to all the circuit parameters which affect system stability and frequency response. Instructions are given on how to identify and avoid these rather subtle and undesirable operating modes by appropriate adjustment of the controls. Details, such as fabrication drawings and a parts list, are provided to enable others to construct the instrument.

  15. Optimization of Single-Sensor Two-State Hot-Wire Anemometer Transmission Bandwidth

    Directory of Open Access Journals (Sweden)

    Paweł Ligęza

    2008-10-01

    Full Text Available Hot-wire anemometric measurements of non-isothermal flows require the use of thermal compensation or correction circuitry. One possible solution is a two-state hot-wire anemometer that uses the cyclically changing heating level of a single sensor. The area in which flow velocity and fluid temperature can be measured is limited by the dimensions of the sensor’s active element. The system is designed to measure flows characterized by high velocity and temperature gradients, although its transmission bandwidth is very limited. In this study, we propose a method to optimize the two-state hot-wire anemometer transmission bandwidth. The method is based on the use of a specialized constanttemperature system together with variable dynamic parameters. It is also based on a suitable measurement cycle paradigm. Analysis of the method was undertaken using model testing. Our results reveal a possible significant broadening of the two-state hot-wire anemometer's transmission bandwidth.

  16. Fiber optic anemometer based on silicon Fabry-Pérot interferometer

    Science.gov (United States)

    Liu, Guigen; Hou, Weilin; Qiao, Wei; Han, Ming

    2015-05-01

    Flowmeters have been finding vast applications in all kinds of industrial processes, such as process control, food quality surveillance, wind turbines, environment monitoring, etc. In this paper, we propose a new anemometer which consists of a Fabry-Pérot interferometer (FPI) implemented using a thin silicon mounted on the tip of an optical fiber. The anemometer takes advantage of the superior thermal and optical properties of silicon. Silicon is transparent to infrared wavelength, while it absorbs visible light. Thus, the silicon FPI can be heated by a beam injected from a red diode laser while the infrared signals go through it without any interference from the heating light. The heat loss from the silicon film will increase when the sensor is placed in stronger flow (wind), which induces a decrease in the optical path of the silicon FPI, which lead to blueshifts the output spectrum. A higher wind speed corresponds to a larger wavelength shift. By tuning the heating power, the response range and sensitivity of the anemometer is changed. Experimental results demonstrate that a wavelength shift -0.574 nm was observed for a wind speed of 4 m/s. Better sensitivity is to be expected when stronger heating applied. The proposed sensor also features simple structure, low cost and fast response.

  17. IMPROVED WIND AND TURBULENCE MEASUREMENTS USING A LOW-COST 3-D SONIC ANEMOMETER AT A LOW-WIND SITE

    Energy Technology Data Exchange (ETDEWEB)

    Bowen, B

    2007-05-11

    A year of data from sonic anemometer and mechanical wind sensors was analyzed and compared at a low-wind site. Results indicate that 15-minute average and peak 1-second wind speeds (u) from the sonic agree well with data derived from a co-located cup anemometer over a wide range of speeds. Wind direction data derived from the sonic also agree closely with those from a wind vane except for very low wind speeds. Values of standard deviation of longitudinal wind speed ({sigma}{sub u}) and wind direction fluctuations ({delta}{sub {theta}}) from the sonic and mechanical sensors agree well for times with u > 2 ms{sup -1} but show significant differences with lower u values. The most significant differences are associated with the standard deviation of vertical wind fluctuations ({sigma}{sub w}): the co-located vertical propeller anemometer yields values increasingly less than those measured by the sonic anemometer as u decreases from 2.5 approaching 0 ms{sup -1}. The combination of u over-estimation and under-estimation of {sigma}{sub w} from the mechanical sensors at low wind speeds causes considerable under-estimation of the standard deviation of vertical wind angle fluctuations ({sigma}{sub {phi}}), an indicator of vertical dispersion. Calculations of {sigma}{sub {phi}} from sonic anemometer measurements are typically 5{sup o} to 10{sup o} higher when the mechanical instruments indicate that {sigma}{sub {phi}} < 5{sup o} or so. The errors in both the propeller anemometer and cup anemometer, caused by their inability to respond to higher frequency (smaller scale) turbulent fluctuations, can therefore lead to large (factors of 2 to 10 or more) errors in the vertical dispersion during stable conditions with light winds.

  18. Assessing indoor low velocity measurements. Pt. 1: Effect of measuring method on quantifying room air flow - comparison LDA - thermal anemometers; Messtechnische Erfassung characteristischer Kenngroessen von Raumluftstroemungen. T. 1: Einfluss der Messmethode bei der Bewertung von Raumluftstroemungen - Vergleich LDA - thermische Anemometer

    Energy Technology Data Exchange (ETDEWEB)

    Sefker, T.; Wolters, T. [Gebr. Trox GmbH, Neukirchen-Vluyn (Germany)

    2004-03-01

    Within the scope of an EU research project, Thermal Anemometers (TA) from different manufacturers were compared by means of a 'Laser Doppler Anemometer' (LDA) under model room conditions. Comparisons were carried out with different kinds of aerodynamic room flows, air change rates and heat loads. This article presents the measuring principle of thermal and 'Laser Doppler Anemometers', it demonstrates the measurements in the scale 1:1, it also demonstrates how the measured air velocities for the estimation of the aerodynamic room flows by means of statistical methods are developed and it presents the results of these measurements. (orig.) [German] Im Rahmen eines EU-Forschungsprojekts wurden Thermische Anemometer (TA) verschiedener Hersteller unter Modellraumbedingungen mit einem Laser Doppler Anemometer (LDA) verglichen. Vergleiche wurden fuer verschiedene Raumstroemungsarten, Luftwechsel und Raumlasten durchgefuehrt. Dieser Beitrag stellt das Messprinzip von thermischen und Laser Doppler Anemometern vor, demonstriert die Messungen im Massstab 1:1, zeigt wie die gemessenen Luftgeschwindigkeiten zur Beurteilung der Raumstroemung mittels statistischen Methoden weiterverarbeitet wurden und praesentiert die Ergebnisse dieser Betrachtungen. (orig.)

  19. Planarised optical fiber composite using flame hydrolysis deposition demonstrating an integrated FBG anemometer.

    Science.gov (United States)

    Holmes, Christopher; Gates, James C; Smith, Peter G R

    2014-12-29

    This paper reports for the first time a planarised optical fiber composite formed using Flame Hydrolysis Deposition (FHD). As a way of format demonstration a Micro-Opto-Electro-Mechanical (MOEMS) hot wire anemometer is formed using micro-fabrication processing. The planarised device is rigidly secured to a silicon wafer using optical quality doped silica that has been deposited using flame hydrolysis and consolidated at high temperature. The resulting structure can withstand temperatures exceeding 580K and is sensitive enough to resolve free and forced convection interactions at low fluid velocity.

  20. Fiber-optic laser-Doppler anemometer microscope applied to the cerebral microcirculation in rats.

    Science.gov (United States)

    Seki, J; Sasaki, Y; Oyama, T; Yamamoto, J

    1996-01-01

    We have applied our developed fiber-optic laser-Doppler anemometer microscope (FLDAM) for the study of the cerebral microcirculation in the rat. The red cell velocity in single pial microvessels was successfully measured through a closed cranial window for the vessel diameter range from 7.8 to 230 microns. The temporal resolution of the FLDAM was sufficiently high to detect the pulsation in the arterioles. Arterio-venous distributions of the temporal mean red cell velocity and wall shear rate are also described.

  1. 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.

  2. Mathematical Relationships Between Two Sets of Laser Anemometer Measurements for Resolving the Total Velocity Vector

    Science.gov (United States)

    Owen, Albert K.

    1993-01-01

    The mathematical relations between the measured velocity fields for the same compressor rotor flow field resolved by two fringe type laser anemometers at different observational locations are developed in this report. The relations allow the two sets of velocity measurements to be combined to produce a total velocity vector field for the compressor rotor. This report presents the derivation of the mathematical relations, beginning with the specification of the coordinate systems and the velocity projections in those coordinate systems. The vector projections are then transformed into a common coordinate system. The transformed vector coordinates are then combined to determine the total velocity vector. A numerical example showing the solution procedure is included.

  3. Optimization of Single-Sensor Two-State Hot-Wire Anemometer Transmission Bandwidth

    OpenAIRE

    Paweł Ligęza

    2008-01-01

    Hot-wire anemometric measurements of non-isothermal flows require the use of thermal compensation or correction circuitry. One possible solution is a two-state hot-wire anemometer that uses the cyclically changing heating level of a single sensor. The area in which flow velocity and fluid temperature can be measured is limited by the dimensions of the sensor’s active element. The system is designed to measure flows characterized by high velocity and temperature gradients, although its tr...

  4. ACCUWIND - Classification of five cup anemometers according to IEC 61400-12-1

    DEFF Research Database (Denmark)

    Friis Pedersen, Troels; Dahlberg, J.-Å.; Busche, P.

    2006-01-01

    The characteristics of five cup anemometers were investigated in detail, and data are presented in figures and tables. The characteristics include: normal wind tunnel calibrations; angular response measurements at 5, 8 and 11m/s; torque coefficient curvemeasurements from combined tilt and ramp-gu...... with artificial wind generators to make classifications according to annex I and J of the standard IEC 61400-12-1 on power performance measurements. Results ofclassification are shown in graphs of systematic deviations and class index tables....

  5. Flowfield characterisation in the wake of a low-velocity heated sphere anemometer

    Energy Technology Data Exchange (ETDEWEB)

    Olim, A.M. [Associacao para o Desenvolvimento da Aerodinamica Industrial (ADAI), Coimbra (Portugal); Riethmuller, M.L. [Von Karman Institute for Fluid Dynamics (VKI), St. Genese (Belgium); Gameiro da Silva, M.C. [Departamento de Engenharia Mecanica, Faculdade de Ciencias e Tecnologia, Universidade de Coimbra Polo II, Coimbra (Portugal)

    2002-06-01

    Heated sphere anemometers (HSA) are the most widely used instruments for low-velocity measurements in the heating, ventilation and air-conditioning industry. Experiments were conducted to characterise the flowfield around the spherically shaped sensor and upper probe assembly of a HSA. Particle image velocimetry was the main quantitative experimental technique. Measurements of the flowfield around a HSA probe and a 2:1 scaled-up model were performed in a uniform isothermal axisymmetrical jet air flow at Re around 350, based on sensor diameter, for different pitch angle incident flows. Additionally, extensive flow visualisation studies around scaled-up models of the HSA probe were performed. (orig.)

  6. Recovery of rectified signals from hot-wire/film anemometers due to flow reversal in oscillating flows.

    Science.gov (United States)

    Yang, Yingchen; Jones, Douglas L; Liu, Chang

    2010-01-01

    Hot-wire/film anemometers have been broadly used in experimental studies in fluid mechanics, acoustics, and ocean engineering. Yet, it is well known that hot-wire/film anemometers rectify the signal outputs due to the lack of sensitivity to flow direction. This main drawback, in turn, makes them less useful for diverse fluctuating flow measurements. To solve this issue, a rectification recovery method has been developed based on reconstruction of the Fourier series expansion in conjunction with signal-squaring approach. This signal recovery method was experimentally examined and proven to be successful for both conventional and microfabricated hot-wire/film anemometers. The method was further applied to dipole field measurements, with data from recovered signals perfectly matching the analytical model of the dipole field.

  7. The hot-film anemometer--a method for blood velocity determination. I. In vitro comparison with the electromagnetic blood flowmeter.

    Science.gov (United States)

    Paulsen, P K

    1980-01-01

    In an invitro flowmodel a constrant temperature hot-film anemometer was tested, using conical needle and catheter-mounted probes. Calibration, linearization and zero-point determination as well as sensitivity change with hematocrit, angulation, flow direction and dirt deposits on the film are described. Curves were compared with those obtained simultaneously from an electromagnetic flowmeter. The hog-film anemometer was direction-insensitive and signals were seen 0.01--0.03 sec before the flowmeter signals. The frequency response of the anemometer was sufficiently higher to register turbulent flow. In 27 simultaneous measurements the mean anemometer results were 6 +/- 8% (+/- SD) higher than the flowmeter results and the peak results correspondingly 16 +/- 6%. Both differences was significant (p anemometer curves were comparable to electromagnetic flowmeter curves. However, certain differences were demonstrated.

  8. The Design and Use of a Temperature-Compensated Hot-Film Anemometer System for Boundary-Layer Flow Transition Detection on Supersonic Aircraft

    Science.gov (United States)

    Chiles, Harry R.

    1988-01-01

    An airborne temperature-compensated hot-film anemometer system has been designed, fabricated, and used to obtain in-flight airfoil boundary-layer flow transition data by the NASA Ames-Dryden Flight Research Facility. Salient features of the anemometer include near constant sensitivity over the full flight envelope, installation without coaxial wiring, low-noise outputs, and self-contained signal conditioning with dynamic and steady-state outputs. The small size, low-power dissipation, and modular design make the anemometer suitable for use in modern high-performance research aircraft. Design of the temperature-compensated hot-film anemometer and its use for flow transition detection on a laminar flow flight research project are described. Also presented are data gathered in flight which is representative of the temperature-compensated hot-film anemometer operation at subsonic, transonic, and supersonic flight conditions.

  9. Theoretical simulation of a 2 micron airborne solid state laser anemometer

    Science.gov (United States)

    Imbert, Beatrice; Cariou, Jean-Pierre

    1992-01-01

    In the near future, military aircraft will need to know precisely their true airspeed in order to optimize flight conditions. In comparison with classical anemometer probes, an airborne Doppler lidar allows measurement of the air velocity without influence from aircraft aerodynamic disturbance. While several demonstration systems of heterodyne detection using a CO2 laser have been reported, improvements in the technology of solid state lasers have recently opened up the possibility that these devices can be used as an alternative to CO2 laser systems. In particular, a diode pumped Tm:Ho:YAG laser allows a reliable compact airborne system with an eye safe wavelength (lambda = 2.09 microns) to be achieved. The theoretical study of performances of a coherent lidar using a solid state diode pumped Tm:Ho:YAG laser, caled SALSA, for measuring aircraft airspeed relative to atmospheric aerosols is described. A computer simulation was developed in order to modelize the Doppler anemometer in the function of atmospheric propagation and optical design. A clever analysis of the power budget on the detector area allows optical characteristic parameters of the system to be calculated, and then it can be used to predict performances of the Doppler system. Estimating signal to noise ratios (SNR) and heterodyne efficiency provides the available energy of speed measurement as well as a useful measurement of the alignment of the backscattered and reference fields on the detector.

  10. A comparison of vertical velocity variance measurements from wind profiling radars and sonic anemometers

    Science.gov (United States)

    McCaffrey, Katherine; Bianco, Laura; Johnston, Paul; Wilczak, James M.

    2017-03-01

    Observations of turbulence in the planetary boundary layer are critical for developing and evaluating boundary layer parameterizations in mesoscale numerical weather prediction models. These observations, however, are expensive and rarely profile the entire boundary layer. Using optimized configurations for 449 and 915 MHz wind profiling radars during the eXperimental Planetary boundary layer Instrumentation Assessment (XPIA), improvements have been made to the historical methods of measuring vertical velocity variance through the time series of vertical velocity, as well as the Doppler spectral width. Using six heights of sonic anemometers mounted on a 300 m tower, correlations of up to R2 = 0. 74 are seen in measurements of the large-scale variances from the radar time series and R2 = 0. 79 in measurements of small-scale variance from radar spectral widths. The total variance, measured as the sum of the small and large scales, agrees well with sonic anemometers, with R2 = 0. 79. Correlation is higher in daytime convective boundary layers than nighttime stable conditions when turbulence levels are smaller. With the good agreement with the in situ measurements, highly resolved profiles up to 2 km can be accurately observed from the 449 MHz radar and 1 km from the 915 MHz radar. This optimized configuration will provide unique observations for the verification and improvement to boundary layer parameterizations in mesoscale models.

  11. 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.

  12. Numerical Simulation on Floating Behavior of Buoyancy Tank Foundation of Anemometer Tower

    Institute of Scientific and Technical Information of China (English)

    丁红岩; 韩艳丽; 张浦阳

    2014-01-01

    The intact stability and damage stability of a model of an anemometer tower with buoyancy tank founda-tion are computed by the finite element software MOSES in this paper. The natural period of the anemometer tower is discussed through frequency domain analysis. The influence of a single factor, such as towing point position, wave height, wave direction and wave period, on towing stability is discussed through time domain analysis. At the same time, the towing stability under the condition of various combinations of many factors is analyzed based on the meas-ured data of the target area. Computer simulation results show that the intact stability is preferable and the damage stability is sufficient under the condition of plenty of subdivisions. Within the scope of the buoyancy tank foundation, the higher the towing point position is, the better the stability is. Wave height has a great impact on the motion ampli-tude of buoyancy tank foundation, but the effect on the acceleration is not obvious;wave period has a great impact on the acceleration, while the effect on the motion amplitude is not obvious;following-waves towing is more conducive to safety than atry.

  13. Fringe mode transmittance laser Doppler microscope anemometer: its adaptation for measurement in the microcirculation.

    Science.gov (United States)

    Einav, S; Berman, H J

    1988-10-01

    Blood flow analysis in the microcirculation requires accurate measurement of velocity, volume flow and shear-rate versus shear-stress relationships. The resolution of most anemometers is too limited to obtain useful measurements, especially near the blood vessel wall and at branches and bifurcations. To make such measurements possible with a noninvasive, high resolution, accurate technique, we have developed a fringe mode, transmittance laser Doppler microscope anemometer (LDMA). This system has an intrinsically high spatial resolution (10 x 12 microns), and does not require a high concentration (10(6)/cm3) of scatters or red blood cells (RBC) as in our application. Preliminary measurements of water flow in a rectangular channel were conducted to ascertain the reliability and accuracy of velocity measurements using the LDMA. Velocity profiles were then measured by the LDMA system in arterioles 38-135 microns in diameter, in the transparent, everted cheek pouch of the anaesthetized hamster. The extremely high resolution of the optical system, and the ultra-fine traversing mechanism of the microscope stage, made velocity readings larger than 0.02 mm/s with accuracy and reproducibility better than 1%, possible near the wall to within 7-10 microns.

  14. Laser transit anemometer measurements on a slender cone in the Langley unitary plan wind tunnel

    Science.gov (United States)

    Humphreys, William M., Jr.; Hunter, William W., Jr.; Covell, Peter F.; Nichols, Cecil E., Jr.

    1990-01-01

    A laser transit anemometer (LTA) system was used to probe the boundary layer on a slender (5 degree half angle) cone model in the Langley unitary plan wind tunnel. The anemometer system utilized a pair of laser beams with a diameter of 40 micrometers spaced 1230 micrometers apart to measure the transit times of ensembles of seeding particles using a cross-correlation technique. From these measurements, boundary layer profiles around the model were constructed and compared with CFD calculations. The measured boundary layer profiles representing the boundary layer velocity normalized to the edge velocity as a function of height above the model surface were collected with the model at zero angle of attack for four different flow conditions, and were collected in a vertical plane that bisected the model's longitudinal center line at a location 635 mm from the tip of the forebody cone. The results indicate an excellent ability of the LTA system to make velocity measurements deep into the boundary layer. However, because of disturbances in the flow field caused by onboard seeding, premature transition occurred implying that upstream seeding is mandatory if model flow field integrity is to be maintained. A description and results of the flow field surveys are presented.

  15. Stratified Turbulence Measurements in Complex Terrain Using Hot-film Probes and a Collocated Sonic Anemometer

    Science.gov (United States)

    Hocut, C.; Kit, E.; Liberzon, D.; Fernando, H. J. S.; Materhorn Team

    2014-11-01

    In the fall of 2012 and spring 2013, the Mountain Terrain Atmospheric Modeling and Observations Program (MATERHORN) conducted extensive field experiments at the Granite Mountain Atmospheric Science Testbed (GMAST), US Army Dugway Proving Grounds (DPG), Utah. This provided a unique opportunity to deploy tower mounted three-dimensional hot-film combo probes, consisting of sonic anemometers collocated with hot-film anemometers able to respond to the wind direction. The combo probes follow mean winds using a feedback control loop and use a Neural Network to calibrate the hot-films in-situ. Once calibrated, these probes can handle a vast range of background flow conditions and scales from mesoscale flow down to the Kolmogorov scale. Of particular interest are the observed variation in velocity spectra during the evenings. Sometimes the velocity spectra shows the turbulence is Kolmogorov and is isotropic at small scales while in other spectra there is evidence of turbulence production at finer scales. An explanation on different spectral shapes will be presented as well as the relevant length/time scales of the production events. Funded by ONR Grant N00014-11-1-0709.

  16. Using a Swinging Vane Anemometer to Measure Airflow. Module 14. Vocational Education Training in Environmental Health Sciences.

    Science.gov (United States)

    Consumer Dynamics Inc., Rockville, MD.

    This module, one of 25 on vocational education training for careers in environmental health occupations, contains self-instructional materials on using a swinging vane anemometer to measure airflow. Following guidelines for students and instructors and an introduction that explains what the student will learn are three lessons: (1) naming each…

  17. Note: Signal conditioning of a hot-film anemometer for a periodic flow rate monitoring system.

    Science.gov (United States)

    Mantovani, Federico; Tagliaferri, Cristian

    2011-12-01

    A flow monitoring system based on a constant temperature hot-film anemometer is presented. The device has been designed to monitor a dispensing process of extremely low quantities of adhesive material. The monitoring device presented in this paper is useful in industrial applications where exact flow speed tracking is not needed, but reliability and tolerance to parameters variability are essential. During the design of the device, problems related to the physical characteristic of the calorimetric sensor, in particular its thermal capacitance, and to the periodic nature of the monitored flow have been taken into account and suitable solutions have been implemented. The schematic representation of the monitoring device together with the experimental results obtained by monitoring fluids with different physical characteristics are presented.

  18. Laser anemometer measurements in a transonic axial-flow fan rotor

    Science.gov (United States)

    Strazisar, Anthony J.; Wood, Jerry R.; Hathaway, Michael D.; Suder, Kenneth L.

    1989-01-01

    Laser anemometer surveys were made of the 3-D flow field in NASA rotor 67, a low aspect ratio transonic axial-flow fan rotor. The test rotor has a tip relative Mach number of 1.38. The flowfield was surveyed at design speed at near peak efficiency and near stall operating conditions. Data is presented in the form of relative Mach number and relative flow angle distributions on surfaces of revolution at nine spanwise locations evenly spaced from hub to tip. At each spanwise location, data was acquired upstream, within, and downstream of the rotor. Aerodynamic performance measurements and detailed rotor blade and annulus geometry are also presented so that the experimental results can be used as a test case for 3-D turbomachinery flow analysis codes.

  19. Spectrum analysis of turbulence in the canine ascending aorta measured with a hot-film anemometer.

    Science.gov (United States)

    Yamaguchi, T; Kikkawa, S; Tanishita, K; Sugawara, M

    1988-01-01

    We measured turbulence velocity in the canine ascending aorta using a hot-film anemometer. Blood flow velocity was measured at various points across the ascending aorta approximately 1.5-2 times the diameter downstream from the aortic valve. The turbulence spectrum was calculated and its characteristics were examined in connection with the mean Reynolds number and/or measuring positions. In the higher wave number range the values of the turbulence spectra were higher at larger mean Reynolds number. In the higher wave number range, the values of the turbulence spectra were higher at points closer to the centerline of the aorta, when the mean Reynolds number was relatively large. The patterns of the turbulence spectra at various points outside the boundary layer on the aortic wall were similar.

  20. Laser anemometer measurements in a transonic axial-flow fan rotor

    Science.gov (United States)

    Strazisar, Anthony J.; Wood, Jerry R.; Hathaway, Michael D.; Suder, Kenneth L.

    1989-11-01

    Laser anemometer surveys were made of the 3-D flow field in NASA rotor 67, a low aspect ratio transonic axial-flow fan rotor. The test rotor has a tip relative Mach number of 1.38. The flowfield was surveyed at design speed at near peak efficiency and near stall operating conditions. Data is presented in the form of relative Mach number and relative flow angle distributions on surfaces of revolution at nine spanwise locations evenly spaced from hub to tip. At each spanwise location, data was acquired upstream, within, and downstream of the rotor. Aerodynamic performance measurements and detailed rotor blade and annulus geometry are also presented so that the experimental results can be used as a test case for 3-D turbomachinery flow analysis codes.

  1. A directional cylindrical anemometer with four sets of differential pressure sensors.

    Science.gov (United States)

    Liu, C; Du, L; Zhao, Z

    2016-03-01

    This paper presents a solid-state directional anemometer for simultaneously measuring the speed and direction of a wind in a plane in a speed range 1-40 m/s. This instrument has a cylindrical shape and works by detecting the pressure differences across diameters of the cylinder when exposed to wind. By analyzing our experimental data in a Reynolds number regime 1.7 × 10(3)-7 × 10(4), we figure out the relationship between the pressure difference distribution and the wind velocity. We propose a novel and simple solution based on the relationship and design an anemometer which composes of a circular cylinder with four sets of differential pressure sensors, tubes connecting these sensors with the cylinder's surface, and corresponding circuits. In absence of moving parts, this instrument is small and immune of friction. It has simple internal structures, and the fragile sensing elements are well protected. Prototypes have been fabricated to estimate performance of proposed approach. The power consumption of the prototype is less than 0.5 W, and the sample rate is up to 31 Hz. The test results in a wind tunnel indicate that the maximum relative speed measuring error is 5% and the direction error is no more than 5° in a speed range 2-40 m/s. In theory, it is capable of measuring wind up to 60 m/s. When the air stream goes slower than 2 m/s, the measuring errors of directions are slightly greater, and the performance of speed measuring degrades but remains in an acceptable range of ±0.2 m/s.

  2. The hot-film anemometer--a method for blood velocity determination. II. In vivo comparison with the electromagnetic blood flowmeter.

    Science.gov (United States)

    Paulsen, P K

    1980-01-01

    Using a constant temperature hot-film anemometer and an electromagnetic blood flowmeter, volumetric flows and velocity profiles were registered in the pulmonary artery, ascending aorta, abdominal aorta and superior vena cava of mongrel dogs. The anemometer registered in 3 out of 4 dogs in the ascending aorta and in 4 out of 5 dogs in the pulmonary artery. The flow profile in these two vessels was flat with a slight deviation with the highest velocity nearer to the posterior wall. In the abdominal aorta the flow profile was sinusoid and in the superior vena cava irregular. In 22 simultaneous measurements anemometer mean results were 97 +/- 23% (+/- SD) of flowmeter results and peak results correspondingly 113 +/- 23%. None of these differences were significant. It is stressed that both qualitatively and quantitatively hot-film anemometer results are comparable to electromagnetic flowmeter results. However, certain differences have been demonstrated.

  3. Laser-optical fiber Bragg grating anemometer for measuring gas flows: application to measuring the electric wind.

    Science.gov (United States)

    Lamb, David W; Hooper, Adam

    2006-04-15

    A novel laser-optical fiber Bragg grating anemometer (FBGA) has been devised for measuring the speed of a moving gas in the range 0-1.5 m s(-1). As a test, the FBGA was applied to measuring the speed of the electric wind generated in the particularly harsh, high-voltage environment of a dc, negative-polarity, partial (corona) discharge in atmospheric air. The instrument proved more stable and yielded an order-of-magnitude improvement in sensitivity (deltav approximately 4 x 10(-3) ms(-1)) compared with other optical-fiber-based anemometers. On-axis wind speeds ranging from zero to 1.1 m s(-1) were measured in the vicinity of the corona discharge.

  4. Hot wire anemometer measurements in the unheated air flow tests of the SRB nozzle-to-case joint

    Science.gov (United States)

    Ramachandran, N.

    1988-01-01

    Hot-Wire Anemometer measurements made in the Solid Rocket Booster (SRB) nozzle-to-case joint are discussed. The study was undertaken to glean additional information on the circumferential flow induced in the SRB nozzle joint and the effect of this flow on the insulation bonding flaws. The tests were conducted on a full-scale, 2-D representation of a 65-in long segment of the SRB nozzle joint, with unheated air as the working fluid. Both the flight Mach number and Reynolds number were matched simultaneously and different pressure gradients imposed along the joint face were investigated. Hot-wire anemometers were used to obtain velocity data for different joint gaps and debond configurations. The procedure adopted for hot-wire calibration and use is outlined and the results from the tests summarized.

  5. Comparing measurements of the horizontal wind speed of a 2D Multi-Lidar and a cup anemometer

    Science.gov (United States)

    Schneemann, Jörge; Trabucchi, Davide; José Trujillo, Juan; Kühn, Martin

    2014-12-01

    Wind measurements of a 2D Multi-Lidar and a mast mounted cup anemometer are compared in this study. Average wind speed and direction as well as the turbulence intensity of the wind speed are considered. Data analysis is mainly performed using standard regression analysis on 10 minute average data and the calculation of the power spectral density. The results show a good agreement regarding wind speed and direction and the turbulence intensity of the horizontal wind.

  6. Turbulent characteristics of a semiarid atmospheric surface layer from cup anemometers – effects of soil tillage treatment (Northern Spain

    Directory of Open Access Journals (Sweden)

    S. Yahaya

    Full Text Available This paper deals with the characteristics of turbulent flow over two agricultural plots with various tillage treatments in a fallow, semiarid area (Central Aragon, Spain. The main dynamic characteristics of the Atmospheric Surface Layer (ASL measured over the experimental site (friction velocity, roughness length, etc., and energy budget, have been presented previously (Frangi and Richard, 2000. The current study is based on experimental measurements performed with cup anemometers located in the vicinity of the ground at 5 different levels (from 0.25 to 4 m and sampled at 1 Hz. It reveals that the horizontal wind variance, the Eulerian integral scales, the frequency range of turbulence and the turbulent kinetic energy dissipation rate are affected by the surface roughness. In the vicinity of the ground surface, the horizontal wind variance logarithmically increases with height, directly in relation to the friction velocity and the roughness length scale. It was found that the time integral scale (and subsequently the length integral scale increased with the surface roughness and decreased with the anemometer height. These variations imply some shifts in the meteorological spectral gap and some variations of the spectral peak length scale. The turbulent energy dissipation rate, affected by the soil roughness, shows a z-less stratification behaviour under stable conditions. In addition to the characterization of the studied ASL, this paper intends to show which turbulence characteristics, and under what conditions, are accessible through the cup anemometer.

    Key words. Meteorology and atmospheric dynamics (climatology, turbulence, instruments and techniques

  7. Using sonic anemometer temperature to measure sensible heat flux in strong winds

    Directory of Open Access Journals (Sweden)

    S. P. Burns

    2012-09-01

    Full Text Available Sonic anemometers simultaneously measure the turbulent fluctuations of vertical wind (w' and sonic temperature (Ts', and are commonly used to measure sensible heat flux (H. Our study examines 30-min heat fluxes measured with a Campbell Scientific CSAT3 sonic anemometer above a subalpine forest. We compared H calculated with Ts to H calculated with a co-located thermocouple and found that, for horizontal wind speed (U less than 8 m s−1, the agreement was around ±30 W m−2. However, for U ≈ 8 m s−1, the CSAT H had a generally positive deviation from H calculated with the thermocouple, reaching a maximum difference of ≈250 W m−2 at U ≈ 18 m s−1. With version 4 of the CSAT firmware, we found significant underestimation of the speed of sound and thus Ts in high winds (due to a delayed detection of the sonic pulse, which resulted in the large CSAT heat flux errors. Although this Ts error is qualitatively similar to the well-known fundamental correction for the crosswind component, it is quantitatively different and directly related to the firmware estimation of the pulse arrival time. For a CSAT running version 3 of the firmware, there does not appear to be a significant underestimation of Ts; however, a Ts error similar to that of version 4 may occur if the CSAT is sufficiently out of calibration. An empirical correction to the CSAT heat flux that is consistent with our conceptual understanding of the Ts error is presented. Within a broader context, the surface energy balance is used to evaluate the heat flux measurements, and the usefulness of side-by-side instrument comparisons is discussed.

  8. Fast-response fiber-optic anemometer with temperature self-compensation.

    Science.gov (United States)

    Liu, Guigen; Hou, Weilin; Qiao, Wei; Han, Ming

    2015-05-18

    We report a novel fiber-optic anemometer with self-temperature compensation capability based on a Fabry-Pérot interferometer (FPI) formed by a thin silicon film attached to the end face of a single-mode fiber. Guided in the fiber are a visible laser beam from a 635 nm diode laser used to heat the FPI and a white-light in the infrared wavelength range as the signal light to interrogate the optical length of the FPI. Cooling effects on the heated sensor head by wind is converted to a wavelength blueshift of the reflection spectral fringes of the FPI. Self-temperature-compensated measurement of wind speed is achieved by recording the difference in fringe wavelengths when the heating laser is turned on and then off. Large thermal-optic coefficient and thermal expansion coefficient of silicon render a high sensitivity that can also be easily tuned by altering the heating laser power. Furthermore, the large thermal diffusivity and the small mass of the thin silicon film endow a fast sensor response.

  9. Design of an anemometer to characterize the flow in the ducts of a hydrogenerator rotor rim

    Science.gov (United States)

    Venne, Kevin; Mydlarski, Laurent; Torriano, Federico; Charest-Fournier, Jean-Philippe; Hudon, Claude; Morissette, Jean-Francois

    2016-11-01

    Due to its complex geometry, the airflow within hydrogenerators is difficult to characterize. And although CFD can be a reliable engineering tool, its application to the field of hydrogenerators is very recent and has certain inherent limitations, which are due in part to geometrical and flow complexities, including the coexistence of moving (rotor) and stationary (stator) components. For this reason, experimental measurements are required to validate the CFD simulations of such complex flows. To this end, a 1:4 scale model of a hydrogenerator was constructed at the IREQ (Hydro-Québec Research Institute) to better understand the flow dynamics in the rotor and stator components, and to help benchmark its CFD simulations. However, new flow sensors must be developed to quantify the flow in the confined and harsh regions of hydrogenerators. Of particular interest is the flow within the rotor rim ducts, since it is directly responsible for cooling one of the most critical components, the poles. This rather complex task required the design of an anemometer that had to be accurate, durable, cost-effective, easy to install, and able to withstand the extreme conditions (temperatures of 50°C, centrifugal forces of 300g, etc.) found in hydrogenerators. This paper presents two preliminary designs of such sensors and a series of tests that were performed to calibrate and test them. Funding graciously provided by the NSERC and FRQNT.

  10. Investigation on Characterizing Heated Pulsating Flows with Hot Wire Anemometers - A Hands-On Approach

    Directory of Open Access Journals (Sweden)

    Marius Alexandru PANAIT

    2014-06-01

    Full Text Available The pulsating heated flows are traditionally a difficult subject to treat with conventional hot wire or film methods. Special factors that complicate matters are flow reversal and non linear flow effects of vortices and wire probe wake disturbances on the heat transfer to the hot film or wire sensor in heated pulsating flows. The presence of these strongly nonlinear and unknown terms leads to great difficulties in calibration of hot film probes in this particular regime. The paper analyses the current state of matters in the field and reports a series of solutions that have been practically tested in a case of a high speed pulsated heated flow. Normally such measurements are made in a non-contact fashion using a LDV system or various visualization techniques but there have been recent attempts to use a constant temperature hot wire anemometer system (CTA.To obtain meaningful calibration for hot wire films in hot pulsating flows, a comparison system on other principles (LDV was used, as well as a specially designed nozzle to replace the calibrator unit that could not be operated with heated fluid due to structural integrity reasons. The method as described below works well for the expected speed range that could be generated using the special nozzle.

  11. Laser anemometer measurements and computations in an annular cascade of high turning core turbine vanes

    Science.gov (United States)

    Goldman, Louis J.; Seasholtz, Richard G.

    1992-01-01

    An advanced laser anemometer (LA) was used to measure the axial and tangential velocity components in an annular cascade of turbine stator vanes designed for a high bypass ratio engine. These vanes were based on a redesign of the first-stage stator, of a two-stage turbine, that produced 75 degrees of flow turning. Tests were conducted on a 0.771 scale model of the engine size stator. The advanced LA fringe system was designed to employ thinner than usual laser beams resulting in a 50-micron-diameter probe volume. Window correction optics were used to ensure that the laser beams did not uncross in passing through the curved optical access port. Experimental LA measurements of velocity and turbulence were obtained both upstream, within, and downstream of the stator vane row at the design exit critical velocity ratio of 0.896 at the hub. Static pressures were also measured on the vane surface. The measurements are compared, where possible with calculations from a 3-D inviscid flow analysis. The data are presented in both graphic and tabulated form so that they may be readily used to compare against other turbomachinery computations.

  12. Is the nacelle mounted anemometer an acceptable option in performance testing?

    Energy Technology Data Exchange (ETDEWEB)

    Dahlberg, J.A. [FFA, The Aeronautical Research Inst. of Sweden, Bromma (Sweden); Frandsen, S.; Madsen, H.A; Antoniou, I.; Friis Pedersen, T. [Risoe National Lab., Roskilde (Denmark); Hunter, R. [RES, Renewable Energy Systems, Glasgow, Scotland (United Kingdom); Klug, H. [DEWI, Wilhelmshaven (Germany)

    1999-03-01

    Although the nacelle anemometer method has been used for power verification purposes for several years, it is only relatively recently that a full understanding of its limitations has emerged. the technique is totally dependent upon the assumption that the nacelle to free wind speed relationship established for a reference turbine in free air can be applied universally to other turbines. Facts emerged from research projects have shown that this assumption is unjustified. In the present paper facts are presented of which some have not been identified nor presented before. E.g. the effect related to wake conditions is novel as a phenomena and the size of the effect can be considerable. The analysis shows that the total error caused by the effects considered in this paper can, in the worst case reach unacceptable high values, 24%, but by taking precautionary measures the errors can be kept at acceptable low levels, 4%. It is found probable that the future use of nacelle anemometry for power performance verification will be subject to strong restrictions. (au)

  13. Laser Anemometer Measurements of the Flow Field in a 4:1 Pressure Ratio Centrifugal Impeller

    Science.gov (United States)

    Skoch, G. J.; Prahst, P. S.; Wernet, M. P.; Wood, J. R.; Strazisar, A. J.

    1997-01-01

    A laser-doppler anemometer was used to obtain flow-field velocity measurements in a 4:1 pressure ratio, 4.54 kg/s (10 lbm/s), centrifugal impeller, with splitter blades and backsweep, which was configured with a vaneless diffuser. Measured through-flow velocities are reported for ten quasi-orthogonal survey planes at locations ranging from 1% to 99% of main blade chord. Measured through-flow velocities are compared to those predicted by a 3-D viscous steady flow analysis (Dawes) code. The measurements show the development and progression through the impeller and vaneless diffuser of a through-flow velocity deficit which results from the tip clearance flow and accumulation of low momentum fluid centrifuged from the blade and hub surfaces. Flow traces from the CFD analysis show the origin of this deficit which begins to grow in the inlet region of the impeller where it is first detected near the suction surface side of the passage. It then moves toward the pressure side of the channel, due to the movement of tip clearance flow across the impeller passage, where it is cut by the splitter blade leading edge. As blade loading increases toward the rear of the channel the deficit region is driven back toward the suction surface by the cross-passage pressure gradient. There is no evidence of a large wake region that might result from flow separation and the impeller efficiency is relatively high. The flow field in this impeller is quite similar to that documented previously by NASA Lewis in a large low-speed backswept impeller.

  14. Design and Implementation of Two-dimensional Ultrasonic Anemometer%二维超声波风速仪

    Institute of Scientific and Technical Information of China (English)

    李聪; 国红玉; 王峰

    2015-01-01

    The measuring principle of ultrasonic anemometer was described in this paper.The calculation formula of v-shaped structure two-dimensional ultrasonic anemometer was deduced based on time difference method.The design method of the ultrasonic anemometer was put forward based on the STM32 microcontroller.The key technology in the implementation process about the ul-trasonic launching LC oscillation frequency selective circuit, signal amplification circuit, second-order active low-pass filter, and active full-wave rectifier filter was described.And the corresponding circuit diagram and the verification results were given.The AR autoregressive model filter algorithm was embedded in the program.Meanwhile, the impact of the temperature on the wind speed and the fluctuating wind field were researched.The experimental results show that the circuit dynamic adaptive ability and anti-in-terference ability are excellent.The two-dimensional ultrasonic anemometer with intelligent algorithm can achieve high precision measurement of wind speed, which has high reference and practical value.%叙述了超声波风速测量的原理,依据时差法的理论推导了V型结构的二维超声波测风速的计算公式,提出了一种基于微控制器STM32的超声波风速仪的设计方法。描述了超声波发射LC振荡选频电路、信号放大电路、二阶有源低通滤波器和有源全波整流滤波的关键技术的实现过程,并给出相应电路图和验证结果,程序融入了AR自回归模型滤波算法。同时对温度对风速影响和脉动风场进行研究。实验结果表明:该电路动态自适应能力强,抗干扰能力较强,配以智能化算法可实现高精度的风速测量,具有较高的参考和实用价值。

  15. Investigation of noise in Lightwave Synthesized Frequency Sweeper seeded LIDAR anemometers from leakage through the Acousto Optic Modulators

    DEFF Research Database (Denmark)

    Pedersen, Anders Tegtmeier; Lindelöw, Per Jonas Petter

    2009-01-01

    Lightwave Synthesized Frequency Sweepers (LSFS) have potential use as lightsources in lidar anemometers. In this paper noise due to leakage in the acousto optic modulators in an LSFS is investigated. Theoretical expressions describing the build-up of noise in the LSFS due to leakage are derived...... Train (FSPT) modulated lidars the leakage will give rise to rapidly growing noise in the bins which corresponds to the signal from low radial wind velocities. It is likely that noise canceling techniques similar to those used for RIN removal has to be deployed for measurements of low wind velocities....

  16. Nowa: Concept of Operation Principle of The Prototype "new Orthogonal Heat-transfer Anemometer"

    Science.gov (United States)

    Scharnhorst, W.; Richner, H.; Joss, J.

    Various meteorological applications ask for long-term measurements of environmen- tal quantities in severe weather conditions at locations difficult to access. So there is a need for robust devices that measure continuously despite of extreme tempera- tures, strong winds, icing and heavy precipitation. The NOWA (Neues Orthogonales Wärmeübergangs-Anemometer) is a heated instrument based on measuring the heat transfer and aiming to fulfil the mentioned requirements. It is 725 mm long using a 337 mm long sensor rod with a diameter of 16 mm. The sensitive elements are placed in the top of the instrument. Apart from wind speed and wind direction, also air temperature, precipitation, and the icing rate are estimated. These quantities are determined by mea- suring temperature values at various locations of the instrument as well as the power needed to keep the sensor and its housing heated. A heated Pt100 is embedded in ce- ramics placed vertically in the centre of the sensor head. Air motion cools the Pt100. Electrical power is used to keep the temperature of the sensor head constant. The power dissipated by the Pt100 is measured. At high wind speed, the wind velocity is determined using the concept of hot-wire anemometry. Four copper-constantane ther- moelements are aligned in North-South- and East-West-direction around the Pt100. In calm air, these elements sense the uniform temperature field created by the heated Pt100 element. Wind will lower the temperature at the Lee-side, whereas the elements placed downwind become warmer. The differences in temperature are related to the wind direction and are used to estimate the wind speed at low velocities. The NOWA is protected against precipitation and icing by its housing and a heated metal screen with a cap. The total heat flux at the instrument's surface can be determined by measur- ing the temperature distribution on the housing. Depending on the weather situation, this heat transfer is either caused by wind

  17. An Analysis of Peak Wind Speed Data from Collocated Mechanical and Ultrasonic Anemometers

    Science.gov (United States)

    Short, David A.; Wells, Leonard; Merceret, Francis J.; Roeder, William P.

    2007-01-01

    This study compared peak wind speeds reported by mechanical and ultrasonic anemometers at Cape Canaveral Air Force Station and Kennedy Space Center (CCAFS/KSC) on the east central coast of Florida and Vandenberg Air Force Base (VAFB) on the central coast of California. Launch Weather Officers, forecasters, and Range Safety analysts need to understand the performance of wind sensors at CCAFS/KSC and VAFB for weather warnings, watches, advisories, special ground processing operations, launch pad exposure forecasts, user Launch Commit Criteria (LCC) forecasts and evaluations, and toxic dispersion support. The legacy CCAFS/KSC and VAFB weather tower wind instruments are being changed from propeller-and-vane (CCAFS/KSC) and cup-and-vane (VAFB) sensors to ultrasonic sensors under the Range Standardization and Automation (RSA) program. Mechanical and ultrasonic wind measuring techniques are known to cause differences in the statistics of peak wind speed as shown in previous studies. The 45th Weather Squadron (45 WS) and the 30th Weather Squadron (30 WS) requested the Applied Meteorology Unit (AMU) to compare data between the RSA ultrasonic and legacy mechanical sensors to determine if there are significant differences. Note that the instruments were sited outdoors under naturally varying conditions and that this comparison was not designed to verify either technology. Approximately 3 weeks of mechanical and ultrasonic wind data from each range from May and June 2005 were used in this study. The CCAFS/KSC data spanned the full diurnal cycle, while the VAFB data were confined to 1000-1600 local time. The sample of 1-minute data from numerous levels on five different towers on each range totaled more than 500,000 minutes of data (482,979 minutes of data after quality control). The ten towers were instrumented at several levels, ranging from 12 ft to 492 ft above ground level. The ultrasonic sensors were collocated at the same vertical levels as the mechanical sensors and

  18. A Comparison of Wind Speed Data from Mechanical and Ultrasonic Anemometers

    Science.gov (United States)

    Short, D.; Wells, L.; Merceret, F.; Roeder, W. P.

    2006-01-01

    This study compared the performance of mechanical and ultrasonic anemometers at the Eastern Range (ER; Kennedy Space Center and Cape Canaveral Air Force Station on Florida's Atlantic coast) and the Western Range (WR; Vandenberg Air Force Base on California's Pacific coast). Launch Weather Officers, forecasters, and Range Safety analysts need to understand the performance of wind sensors at the ER and WR for weather warnings, watches, advisories, special ground processing operations, launch pad exposure forecasts, user Launch Commit Criteria (LCC) forecasts and evaluations, and toxic dispersion support. The current ER and WR weather tower wind instruments are being changed from the current propeller-and-vane (ER) and cup-and-vane (WR) sensors to ultrasonic sensors through the Range Standardization and Automation (RSA) program. The differences between mechanical and ultrasonic techniques have been found to cause differences in the statistics of peak wind speed in previous studies. The 45th Weather Squadron (45 WS) and the 30th Weather Squadron (30 WS) requested the Applied Meteorology Unit (AMU) to compare data between RSA and current sensors to determine if there are significant differences. Approximately 3 weeks of Legacy and RSA wind data from each range were used in the study, archived during May and June 2005. The ER data spanned the full diurnal cycle, while the WR data was confined to 1000-1600 local time. The sample of 1-minute data from numerous levels on 5 different towers on each range totaled more than 500,000 minutes of data (482,979 minutes of data after quality control). The 10 towers were instrumented at several levels, ranging from 12 ft to 492 ft above ground level. The RSA sensors were collocated at the same vertical levels as the present sensors and typically within 15 ft horizontally of each another. Data from a total of 53 RSA ultrasonic sensors, collocated with present sensors were compared. The 1-minute average wind speed/direction and the 1

  19. Two-component laser Doppler anemometer for measurement of velocity and turbulent shear stress near prosthetic heart valves.

    Science.gov (United States)

    Woo, Y R; Yoganathan, A P

    1985-01-01

    The velocity and turbulent shear stress measured in the immediate vicinity of prosthetic heart valves play a vital role in the design and evaluation of these devices. In the past hot wire/film and one-component laser Doppler anemometer (LDA) systems were used extensively to obtain these measurements. Hot wire/film anemometers, however, have some serious disadvantages, including the inability to measure the direction of the flow, the disturbance of the flow field caused by the probe, and the need for frequent calibration. One-component LDA systems do not have these problems, but they cannot measure turbulent shear stresses directly. Since these measurements are essential and are not available in the open literature, a two-component LDA system for measuring velocity and turbulent shear stress fields under pulsatile flow conditions was assembled under an FDA contract. The experimental methods used to create an in vitro data base of velocity and turbulent shear stress fields in the immediate vicinity of prosthetic heart valves of various designs in current clinical use are also discussed.

  20. Universal miniaturized signal evaluation for laser doppler anemometers; Universelle Miniatur-Signalauswertung fuer die Laser Doppler Anemometrie

    Energy Technology Data Exchange (ETDEWEB)

    Wnuck, J. von; Strunck, V.; Dopheide, D.

    1994-01-01

    A laser doppler anemometer (LDA) is a contactless optical sensor for flow rate measurement. Interference of two laser beams generates a measuring volume with interference lines in the point of intersection. A particle moving through the measuring volume with a current scatters light modulated wiith the doppler frequency, which is received by a detector. The frequency of the doppler-modulated light is proportional to the velocity of the particle. The report describes the technical details of an electronic evaluation system for laser doppler signals in the time range using programmable gate arrays by Xilinix. (orig.) [Deutsch] Ein Laser Doppler Anemometer (LDA) ist ein beruehrungsloser optischer Sensor, der Stroemungsgeschwindigkeiten misst. Die Ueberlagerung zweier Laserstrahlen erzeugt im Schnittpunkt ein Messvolumen mit Inferenzstreifen. Ein Teilchen, das sich mit einer Stroemung durch das Messvolumen bewegt, streut mit der Doppelfrequenz des Doppler moduliertes Licht, das von einem Detektor empfangen wird. Die Frequenz des Doppler-modulierten Lichts ist der Geschwindigkeit des Teilchens proportional. Hier wird die technische Realisierung einer Auswerteelektronik fuer Laser Doppler Signale im Zeitbereich mit programmierbaren Gate-Arrays von Xilinx beschrieben. (orig.)

  1. Expired tidal volumes measured by hot-wire anemometer during high-frequency oscillation in preterm infants.

    Science.gov (United States)

    Zimová-Herknerová, Magdalena; Plavka, Richard

    2006-05-01

    We sought to determine the normocapnic values of expiratory tidal volume measured by hot-wire anemometer, and to evaluate how often expiratory tidal volume exceeds estimated anatomical dead space during high-frequency oscillatory ventilation (HFOV) in preterm infants. We also sought to determine the relationship between expiratory tidal volume and other respiratory parameters. The neonatal respiration monitor SLE 2100 VPM, a hot-wire anemometer, was used to measure expired tidal volume (V(T,E)) in patients ventilated by the Sensormedics 3,100A during routine clinical use of HFOV. Two hundred and fourteen simultaneous measurements of PaCO(2), V(T,E), fraction of inspired oxygen (FiO(2)), continuous distending pressure (CDP), frequency, and amplitude were obtained from 28 patients. The median birth weight was 852 g (range, 435-3,450 g), and median gestational age was 27.2 weeks (range, 23.3-41.0 weeks). One hundred and eighteen (55%) normocapnic measurements, 42 (20%) hypocapnic measurements, and 54 (25%) hypercapnic measurements were recorded in which the median V(T,E) was 1.67 ml/kg (95% confidence interval (CI), 1.55-1.79), 1.94 ml/kg (95% CI, 1.74-2.14), and 1.54 ml/kg (95% CI, 1.42-1.66), respectively. The measured V(T,E) exceeded 2.0 ml/kg in 30 instances of normocapnic V(T,E) (14%) and 54 of all V(T,E) (25%), and 3 ml/kg only in 7 (3%) and 11 (5%) instances of normocapnic and all V(T,E). There was a significant difference in median normocapnic V(T,E) obtained when FiO(2) was between 0.21-0.35, compared to values obtained when FiO(2) was 0.36-1.0 (1.61 ml/kg (95% CI, 1.52-1.70) vs. 2.06 ml/kg (95% CI, 1.93-2.19), P 47 should predict hypercapnia in 81% of cases. In conclusion, expired tidal volume measurement by heated double-wire anemometer sensor is feasible, provides useful real-time information about tidal volume changes, and may improve the clinical management of HFOV.

  2. Measurement of turbulence intensity in the center of the canine ascending aorta with a hot-film anemometer.

    Science.gov (United States)

    Yamaguchi, T; Kikkawa, S; Yoshikawa, T; Tanishita, K; Sugawara, M

    1983-05-01

    The blood flow velocity near the central axis of the canine ascending aorta was measured with a hot-film anemometer. The cardiac output and the heart rate were controlled at will by means of an extracorporeal circulation and by atrial pacing. The turbulent component of the blood flow velocity was calculated using an ensemble average technique. Ensemble average turbulent intensity was also calculated to show the time course of turbulence in the aorta. The ratio of the mean turbulence intensity to the time mean sectional average velocity in the aorta was constant in most animals regardless of the changes in fluid mechanical parameters. The correlation between the frequency parameter and the relative mean turbulence intensity was weakly positive. The power spectrum of the turbulence was also calculated.

  3. Estimating mechanical blood trauma in a centrifugal blood pump: laser Doppler anemometer measurements of the mean velocity field.

    Science.gov (United States)

    Pinotti, M; Paone, N

    1996-06-01

    A laser Doppler anemometer (LDA) was used to obtain the mean velocity and the Reynolds stress fields in the inner channels of a well-known centrifugal vaneless pump (Bio-pump). Effects of the excessive flow resistance against which an occlusive pump operates in some surgical situations, such as cardiopulmonary bypass, are illustrated. The velocity vector field obtained from LDA measurements reveals that the constraint-forced vortex provides pumping action in a restricted area in the core of the pump. In such situations, recirculating zones dominate the flow and consequently increase the damage to blood cells and raise the risk of thrombus formation in the device. Reynolds normal and shear stress fields were obtained in the entry flow for the channel formed by two rotating cones to illustrate the effects of flow disturbances on the potential for blood cell damage.

  4. Steady flow in a model of the human carotid bifurcation. Part II--laser-Doppler anemometer measurements.

    Science.gov (United States)

    Bharadvaj, B K; Mabon, R F; Giddens, D P

    1982-01-01

    The evidence for hypothesizing a relationship between hemodynamics and atherogenesis as well as the motivation for selecting the carotid bifurcation for extensive fluid dynamic studies has been discussed in Part I of this two-paper sequence. Part II deals with velocity measurements within the bifurcation model described by Fig. 1 and Table 1 of the previous paper. A plexiglass model conforming to the dimensions of the average carotid bifurcation was machined and employed for velocity measurements with a laser-Doppler anemometer (LDA). The objective of this phase of the study was to obtain quantitative information on the velocity field and to estimate levels and directions of wall shear stress in the region of the bifurcation.

  5. The measurement of sperm motility by the fibre optic Doppler anemometer as a prediction of bovine fertility

    Science.gov (United States)

    Bullock, J. G.; Ross, D. A.

    The fibre optic Doppler anemometer (FODA) has been used to develop an accurate quantitative method of routinely assessing bull fertility. This method is of importance to the artificial insemination industry because the present qualitative estimation, performed by viewing semen using a microscope, can only set broad limits of quality. Laser light from the FODA was directed into diluted semen samples and the back scattered light was measured. A digital correlator was used to calculate the signal correlation of the back scattered light. The resultant data curves were interpreted in terms of the collective motility and swimming speed of the spermatozoa using a microcomputer. These two parameters are accepted as being indicative of fertility. The accuracy of this method is demonstrated by examination of results obtained in an experiment where enzymes, thought to alter fertility, were added to semen. The effect of the enzymes on the swimming speed and motility was clearly demonstrated.

  6. A Bayesian model to correct underestimated 3-D wind speeds from sonic anemometers increases turbulent components of the surface energy balance

    Science.gov (United States)

    Frank, John M.; Massman, William J.; Ewers, Brent E.

    2016-12-01

    Sonic anemometers are the principal instruments in micrometeorological studies of turbulence and ecosystem fluxes. Common designs underestimate vertical wind measurements because they lack a correction for transducer shadowing, with no consensus on a suitable correction. We reanalyze a subset of data collected during field experiments in 2011 and 2013 featuring two or four CSAT3 sonic anemometers. We introduce a Bayesian analysis to resolve the three-dimensional correction by optimizing differences between anemometers mounted both vertically and horizontally. A grid of 512 points (˜ ±5° resolution in wind location) is defined on a sphere around the sonic anemometer, from which the shadow correction for each transducer pair is derived from a set of 138 unique state variables describing the quadrants and borders. Using the Markov chain Monte Carlo (MCMC) method, the Bayesian model proposes new values for each state variable, recalculates the fast-response data set, summarizes the 5 min wind statistics, and accepts the proposed new values based on the probability that they make measurements from vertical and horizontal anemometers more equivalent. MCMC chains were constructed for three different prior distributions describing the state variables: no shadow correction, the Kaimal correction for transducer shadowing, and double the Kaimal correction, all initialized with 10 % uncertainty. The final posterior correction did not depend on the prior distribution and revealed both self- and cross-shadowing effects from all transducers. After correction, the vertical wind velocity and sensible heat flux increased ˜ 10 % with ˜ 2 % uncertainty, which was significantly higher than the Kaimal correction. We applied the posterior correction to eddy-covariance data from various sites across North America and found that the turbulent components of the energy balance (sensible plus latent heat flux) increased on average between 8 and 12 %, with an average 95 % credible

  7. 海上测风塔单桩基础设计与分析%Design and Analysis of Single Pile Foundation of Offshore Anemometer Tower

    Institute of Scientific and Technical Information of China (English)

    彭才智

    2015-01-01

    This paper induced the design points of the single pile foundation of offshore anemometer tower and proposed its design method combining with the environmental characteristics of offshore anemometer towers . A design example was analyzed , which provides a reference for similar engineering .%在归纳了海上测风塔单桩基础的设计要点的基础上,通过结合某海上测风塔基础设计实例与海上测风塔环境等特点进行了分析,提出了海上测风塔单桩基础的设计方法,为类似工程提供参考。

  8. Design and Implementation of Anemometer Testing Device%测风传感器测试仪的设计与实现

    Institute of Scientific and Technical Information of China (English)

    王建晓; 胡桐; 李春立; 王东明

    2015-01-01

    This article presents the design and implement procedure of Anemometer Testing Device which is based on low power chip AVR ATMEGA1280. Experiment results show that the Anemometer Testing Device improves the testing efficien-cy while decreases the testing cost.%文章介绍了用低功耗的8位AVR单片机ATMEGA1280设计测风传感器测试仪的思路和功能。经使用证明,测风传感器测试仪能提高传感器的测试效率和降低传感器检测成本,增加传感器测试的灵活性。

  9. 三维超声波测风仪原理与应用%Theory and Applications of Three-Dimensional Ultrasonic Anemometer

    Institute of Scientific and Technical Information of China (English)

    张捷光; 齐文新; 齐宇

    2013-01-01

    超声波测风是超声波检测技术在气体介质中的一种新的应用.文章描述了三维超声波测风仪较之传统二维测风仪的优点,给出了超声波测风的原理并对其中的直接时差测风法作了详细介绍,最后给出了几种典型的三维超声波测风仪的应用领域.%Using of ultrasonic in the measurement of wind speed is one of the new applications of ultrasonic technology in gas medium. This article describes the advantages of three-dimensional ultrasonic anemometer compared to the traditional two-dimensional anemometer, explains the theory, then gives a detailed description to the direct time difference method, and finally lists some of the typical application fields of three-dimensional ultrasonic anemometer.

  10. Turbulent characteristics of a semiarid atmospheric surface layer from cup anemometers A~é effects of soil tillage treatment (Northern Spain)

    Science.gov (United States)

    Yahaya, S.; Frangi, J. P.; Richard, D. C.

    2003-10-01

    This paper deals with the characteristics of turbulent flow over two agricultural plots with various tillage treatments in a fallow, semiarid area (Central Aragon, Spain). The main dynamic characteristics of the Atmospheric Surface Layer (ASL) measured over the experimental site (friction velocity, roughness length, etc.), and energy budget, have been presented previously (Frangi and Richard, 2000). The current study is based on experimental measurements performed with cup anemometers located in the vicinity of the ground at 5 different levels (from 0.25 to 4 m) and sampled at 1 Hz. It reveals that the horizontal wind variance, the Eulerian integral scales, the frequency range of turbulence and the turbulent kinetic energy dissipation rate are affected by the surface roughness. In the vicinity of the ground surface, the horizontal wind variance logarithmically increases with height, directly in relation to the friction velocity and the roughness length scale. It was found that the time integral scale (and subsequently the length integral scale) increased with the surface roughness and decreased with the anemometer height. These variations imply some shifts in the meteorological spectral gap and some variations of the spectral peak length scale. The turbulent energy dissipation rate, affected by the soil roughness, shows a z-less stratification behaviour under stable conditions. In addition to the characterization of the studied ASL, this paper intends to show which turbulence characteristics, and under what conditions, are accessible through the cup anemometer.

  11. Laser transit anemometer and Pitot probe comparative measurements in a sharp cone boundary layer at Mach 4

    Science.gov (United States)

    Hunter, W. W., Jr.; Ocheltree, S. L.; Russ, C. E., Jr.

    1991-01-01

    Laser transit anemometer (LTA) measurements of a 7 degree sharp cone boundary layer were conducted in the Air Force/AEDC Supersonic Tunnel A Mach 4 flow field. These measurements are compared with Pitot probe measurements and tricone theory provided by AEDC staff. Measurements were made both in laminar and turbulent boundary layers of the model. Comparison of LTA measurements with theory showed agreement to better than 1 percent for the laminar boundary layer cases. This level of agreement was obtained after small position corrections, 0.01 to 0.6 mm, were applied to the experimental data sets. Pitot probe data when compared with theory also showed small positioning errors. The Pitot data value was also limited due to probe interference with the flow near the model. The LTA turbulent boundary layer data indicated a power law dependence of 6.3 to 6.9. The LTA data was analyzed in the time (Tau) domain in which it was obtained and in the velocity domain. No significant differences were noted between Tau and velocity domain results except in one turbulent boundary layer case.

  12. Unsteady fluid dynamics of several mechanical prosthetic heart valves using a two component laser Doppler anemometer system.

    Science.gov (United States)

    Akutsu, T; Modi, V J

    1997-10-01

    Five typical mechanical heart valves (Starr-Edwards, Björk-Shiley convexo-concave (c-c), Björk-Shiley monostrut, Bicer-Val, and St. Jude Medical) were tested in the mitral position under the pulsatile flow condition. The test program included measurements of velocity and turbulent stresses at 5 downstream locations. The study was carried out using a sophisticated cardiac simulator in conjunction with a highly sensitive 2 component laser Doppler anemometer (LDA) system. The continuous monitoring of parametric time histories revealed useful details about the complex flow and helped to establish the locations and times of the peak parameter values. Based upon the nondimensional presentation of data, the following general conclusions can be made. First, all the 5 valve designs created elevated turbulent stresses during the accelerating and peak flow phases, presenting the possibility of thromboembolism and perhaps hemolysis. Second, the difference in valve configuration seemed to affect the flow characteristics; third, the bileaflet design of the St. Jude valve appeared to create a lower turbulence stress level.

  13. Laser anemometer measurements and computations for transonic flow conditions in an annular cascade of high turning core turbine vanes

    Science.gov (United States)

    Goldman, Louis J.

    1993-01-01

    An advanced laser anemometer (LA) was used to measure the axial and tangential velocity components in an annular cascade of turbine stator vanes operating at transonic flow conditions. The vanes tested were based on a previous redesign of the first-stage stator in a two-stage turbine for a high-bypass-ratio engine. The vanes produced 75 deg of flow turning. Tests were conducted on a 0.771-scale model of the engine-sized stator. The advanced LA fringe system employed an extremely small 50-micron diameter probe volume. Window correction optics were used to ensure that the laser beams did not uncross in passing through the curved optical access port. Experimental LA measurements of velocity and turbulence were obtained at the mean radius upstream of, within, and downstream of the stator vane row at an exit critical velocity ratio of 1.050 at the hub. Static pressures were also measured on the vane surface. The measurements are compared, where possible, with calculations from a three-dimensional inviscid flow analysis. Comparisons were also made with the results obtained previously when these same vanes were tested at the design exit critical velocity ratio of 0.896 at the hub. The data are presented in both graphical and tabulated form so that they can be readily compared against other turbomachinery computations.

  14. Instantaneous velocity measurement of AC electroosmotic flows by laser induced fluorescence photobleaching anemometer with high temporal resolution

    Science.gov (United States)

    Zhao, Wei; Yang, Fang; Qiao, Rui; Wang, Guiren; Rui Qiao Collaboration

    2015-11-01

    Understanding the instantaneous response of flows to applied AC electric fields may help understand some unsolved issues in induced-charge electrokinetics and enhance performance of microfluidic devices. Since currently available velocimeters have difficulty in measuring velocity fluctuations with frequency higher than 1 kHz, most experimental studies so far focus only on the average velocity measurement in AC electrokinetic flows. Here, we present measurements of AC electroosmotic flow (AC-EOF) response time in microchannels by a novel velocimeter with submicrometer spatial resolution and microsecond temporal resolution, i.e. laser-induced fluorescence photobleaching anemometer (LIFPA). Several parameters affecting the AC-EOF response time to the applied electric signal were investigated, i.e. channel length, transverse position and solution conductivity. The experimental results show that the EOF response time under a pulsed electric field decreases with the reduction of the microchannel length, distance between the detection position to the wall and the conductivity of the solution. This work could provide a new powerful tool to measure AC electrokinetics and enhance our understanding of AC electrokinetic flows.

  15. Fiber-optic laser-Doppler anemometer microscope developed for the measurement of microvascular red cell velocity.

    Science.gov (United States)

    Seki, J

    1990-11-01

    A fiber-optic laser-Doppler anemometer microscope (FLDAM) was developed and its applicability to the study of microvascular blood flow was examined by measuring red cell velocities in vivo and in vitro. The FLDAM consists of an intravital microscope equipped with a fringe-mode back-scatter LDA. A data processing method of the Doppler signal which used frequency averaging over the entire frequency range of the power spectrum was developed. Spatial resolution of the FLDAM varied from 17 to 200 microns with 50X to 5X objectives. In vitro experiments showed that the red cell velocity obtained by the FLDAM was equal to the mean flow velocity, within the accuracy of the measurements, for tube diameters from 35 to 100 microns, mean velocity from 0.7 to 17 mm/sec, and feed hematocrit of 20%, when 10X or 20X objectives were used. In vivo red cell velocity measurements conducted with the FLDAM in microvessels of rat mesentery with diameters from 6.5 to 49 microns showed that red cell velocities were about 1/1.6 times smaller than those obtained by the two-slit technique, which also suggests that the velocity obtained by the FLDAM corresponds to the mean flow velocity. This relationship was also established from theoretical considerations for the case where the FLDAM sampling volume covers the entire vessel cross section. Furthermore the frequency response of the FLDAM was established to be about 20 Hz, which was sufficient for measurement of pulsatile velocities in rat mesenteric microvessels.

  16. Flow visualization and 1- and 3-D laser-Doppler-anemometer measurements in models of human carotid arteries.

    Science.gov (United States)

    Liepsch, D; Pflugbeil, G; Matsuo, T; Lesniak, B

    1998-04-01

    Pulsatile flow, wall distensibility, non-Newtonian flow characteristics of blood in flow separation regions, and high/low blood pressure were studied in elastic silicon rubber models having a compliance similar to human vessels and the same surface structure as the biological intima models of (1) a healthy carotid artery model, (2) a 90% stenosis in the ICA, and (3) 80% stenosis in both the internal and external carotid arteries. Flow was visualized for steady flow and pulsatile studies to localize flow separation regions and reattachment points. Local velocity was measured with a 1-, 2-, or 3-D laser-Doppler-anemometer (LDA). Flow in the unstenosed model was Re = 250. In the stenosed models, the Re number decreased to Re = 180 and 213 under the same experimental conditions. High velocity fluctuations with vortices were found in the stenosed models. The jet flow in the stenosis increased up to 4 m/s. With an increasing bifurcation angle, the separation regions in the ECA and ICA increased. Increased flow (Re = 350) led to an increase in flow separation and high velocity shear gradients. The highest shear stresses were nearly 20 times higher than normal. The 90% stenosis created high velocity shear gradients and velocity fluctuations. Downstream of the stenoses, eddies were found over the whole cross-section. In the healthy model a slight flow separation region was observed in the ICA at the branching cross-section whereas in the stenosed models, the flow separation regions extended far into the ICA. We conclude that a detailed understanding of flow is necessary before vascular surgery is performed especially before artificial grafts or patches are implanted.

  17. 基于Zigbee技术的矿用无线智能便携式风速表%Coal mine wireless intelligence portable anemometer based on Zigbee technology

    Institute of Scientific and Technical Information of China (English)

    秦宪礼; 付明超

    2011-01-01

    为解决目前煤矿风速检测工作中存在的问题,采用基于Zigbee技术的无线微控器CC2430设计了具有无线通信功能的便携式智能风速表.给出了风速表总体结构,并介绍了详细的软硬件设计.在通风仿真实验室环境下进行了风速测量及无线通信试验,结果显示该风速表提高了风速检测的准确性,完成了数据的传输功能并实现了对检测人员的跟踪.该风速表的设计大大提高了风速检测的效率,对风速检测工作起到了有效的监督作用.%In order to solve the problems existing in coal mine wind speed measurement, the intelligence portable anemometer with wireless communication function was designed by using CC2430 which is a RF microcontroller based on Zigbee technology. The framework of the anemometer was given, and the detailed design of the software and hardware was introduced. Wind speed measurement and wireless communications test were carried out in ventilation simulation laboratory, and the results showed that the accuracy of wind speed measurement was improved, and data transmission capabilities and testing personnel tracks were realized. The design of the anemometer greatly improved the efficiency of wind speed measurement, and played an effective supervisory role to wind speed measurement.

  18. A method of measuring the three-dimensional mean flow and turbulence quantities inside a rotating turbo-machinery passage. [by hot-wire anemometer

    Science.gov (United States)

    Gorton, C. A.; Lakshminarayana, B.

    1975-01-01

    A method of measuring the three-dimensional components of mean velocity and turbulence quantities within a rotating turbomachinery passage is developed through the use of hot wire anemometry techniques. Equations are derived which, when solved simultaneously and in conjunction with the data obtained from the hot wire anemometer measurements, will provide values for the radial, axial and tangential components of mean velocity, turbulence intensity and turbulence stress within the rotating turbomachinery passage. A three-bladed rocket pump inducer model, operating in air, was used in the experimentation. The method is very accurate and provides very useful information on the characteristics of the flow inside rotor passages hitherto unexplored.

  19. 高精度超声风速测量系统设计与实现%Design and Implementation of High Accuracy Ultrasonic Anemometer

    Institute of Scientific and Technical Information of China (English)

    丁向辉; 李平; 孟晓辉

    2011-01-01

    时差法是超声风速风向测量系统的基本方法.文中首先对影响时差法测量精度的因素进行分析,针对这些影响因素,在超声换能器设计、阵型设计、电路系统设计和信号处理算法等方面提出了提高系统精度的设计方案,并制成样机.实验测试表明,文中所实现的系统已经基本达到国际尖端产品的测量精度,且具有体积小、可靠性高等优点,具有很高的实际应用价值.%In ultrasonic anemometer systems,time difference measurement method is used in wide range. The factors that affect the time difference measurement accuracy were analyzed. According to the analysis, the ultrasonic transducer design , system mechanical structure,system circuit design and signal processing; methods were discussed. A high accuracy ultrasonic anemometer 8ystem solution was designed. The prototype system was implemented. Experiments show that the proposed system has reached the same performance as the top products on shelf. Besides , the system has small size , high resolution and reliability , which is valuable in practice.

  20. Design of Wireless Ultrasonic Anemometer Based on ARM and CPLD%基于ARM和CP LD的无线风速仪设计∗

    Institute of Scientific and Technical Information of China (English)

    陆健; 张自嘉

    2014-01-01

    分析了在平面三角形阵列中利用超声波时差法测量风速风向的基本原理,设计了基于ARM和CPLD微处理器的无线风速仪。给出了以LPC1768和EPM240T100C5芯片为核心的超声波无线风速仪的设计实现方法。重点阐述了超声波驱动电路、信号调理电路、无线收发模块以及系统软件的设计。实验结果表明,该系统可以精确测量风速与风向,且工作可靠稳定。%The principle of measurement of wind speed and direction using ultrasonic Time-of-Flight was introduced in the triangle array. The design of ultrasonic anemometer based on ARM and CPLD was described. The method of ultrasonic anemometer based on LPC1768 and EPM240T100C5 was given. The driving circuit,signal conditioning circuit,wireless transceiver module and the software design were introduced. The experiments testify the system can accurately measure wind speed and direction. It also has other advantages such as good reliability.

  1. Study of in situ calibration performance of co-located multi-sensor hot-film and sonic anemometers using a ‘virtual probe’ algorithm

    Science.gov (United States)

    Vitkin, L.; Liberzon, D.; Grits, B.; Kit, E.

    2014-07-01

    The performance of an in situ calibration technique, implementing neural network (NN) algorithms for co-located multi-wire hot-film and sonic anemometers, is studied. The NN-based calibration technique, proposed by Kit et al (2010 J. Atmos. Ocean. Technol. 27 23-41), allows performing direct measurement of fine scales in turbulent air flow, and offers a robust tool for measurements of micro-scale properties in atmospheric flows. Accuracy of the suggested calibration technique is examined in view of isotropic and anisotropic flow fields of various turbulence intensity (TI). Anisotropic velocity datasets of various TIs were generated using a ‘virtual probe’ simulating hot-film anemometer response to the sensed flow, while a kinematic model of homogeneous isotropic turbulent flow was implemented to generate isotropic flow datasets. NN calibration performance is examined by quantitative comparison between the original and reconstructed velocity components, using a specially constructed norm and by visual comparison of original and reconstructed time series. The examined NN calibration technique performance is shown to be of reasonable accuracy for all TI velocity fields examined, while a notable drop in accuracy is detected with the increase in TI. The reconstruction of isotropic velocity fields, using the NN algorithm for calibration, is apparently of slightly lower accuracy than in the case of anisotropic flows. The results are discussed in view of possible implementation of the suggested technique in direct field measurements of atmospheric turbulence fine scales.

  2. 组合热膜式流速矢量传感器%Combined hot-film anemometers for measuring flow speed vectors

    Institute of Scientific and Technical Information of China (English)

    阙瑞义; 朱荣; 刘鹏; 周兆英

    2011-01-01

    To realize the measurement of the air flow vector on a Micro Air Vehicle(MAV), a new type of hot-film anemometer which was lighter than a pitot and firmer than a hot-wire anemometer was developed and a corresponding combined system was also presented. Similar to the hot-wire anemometer, the hot-film anemometer is sensitive to both magnitude and direction of flow speed,and its output is a resistance when either the flow magnitude or direction changes. Moreover, by combining the sensor array simply, the flow speed vector could be acquired in a angle range, and thus its application area was expanded. Based on the experimental tests on the sensor characteristics, the principles and conditions of the combination scheme were researched,the method to arrange the sensor array was given and the speed vector measuring error was discussed. The experimental results indicate that arranging 3 hot-film anemometers with a separation angle of 45° to form a combination system can measure the flow vector in the angle range of 180°. Both of theoretical and experimental results prove that the presented combination method is effective and feasible,and its volume and energy consume are both lower than those of traditionnl methods.It can be further expanded to other flow sensors with similar characters.%针对在微型飞行器上测量空气流速矢量的需要,提出了一种比空速管轻巧、比热线式流速传感器抗干扰能力强的微型热膜式流速传感器及其组合系统.与热线式流速传感器相似,热膜流速传感器仅输出电阻值信息,对流速和流向均敏感.将多个传感器按照一定规律组合,可实现对一定角度范围内的流速矢量的测量,从而拓展其应用.结合试验推导了组合传感器测量流速矢量的原理与实现条件,讨论了传感器布置的优化方式并进行了误差分析.传感器特性的实验结果表明,按照45°间隔角布置的3个热膜式流速传感器联合,可以测量180°范围的

  3. Low-power anemometer

    Science.gov (United States)

    Gilje, R. I.; Lehman, W.

    1977-01-01

    Device allows wind speeds to be measured with less power by alternating hot-wire or hot-film heating periods with measurement periods. System includes reference auxiliary circuits to generate V sub ref and ramp voltage (E sub 3) and reference half of bridge circuit. Circuit permits use of several sensing films with common temperature compensation sensor.

  4. The Uncertainty Evaluation of Value Error by Mine Anemometer Calibrating Device%矿用风速表示值误差的测量不确定度评定

    Institute of Scientific and Technical Information of China (English)

    赵镇川

    2013-01-01

      通过矿用风速表检定装置对风速表示值误差进行不确定度评定。%  It processed uncertainty evaluation of wind speed value error through mine anemometer calibrating device.

  5. 计数式光纤Bragg光栅风速仪设计%Design of fiber Bragg grating anemometer using principle of number counting

    Institute of Scientific and Technical Information of China (English)

    景霞; 刘爱莲; 赵振刚; 谢涛; 李英娜; 肖范; 李川

    2015-01-01

    To eliminate influence of temperature fluctuations on wind speed measurement with anemometer,design a kind of fiber Bragg grating( FBG)anemometer using principle of number counting effectively and stably measure wind speed. This kind of anemometer has a wind cup,which has a speed cam,and the counting device consists of speed cam and a balanceable cantilever on which FBG is pasted. Based on linear relationship between wind speed and revolving speed of the wind cup,build sensing model,then can calculate according to numbers of central light wave changes,calculate wind speed and monitor wind speed live in the aim area. Wind tunnel experiments show that wind speed sensor using principle of number counting start up wind speed is 0. 9 m/s,linearity is 6% and sensitivity is 0. 65 r/m.%为消除温度波动变化对风速测量带来的影响,能更有效、稳定地测量风速,设计一种计数式光纤Bragg光栅( FBG)风速仪。风速仪采用风杯结构,在风杯转轮上设置转速凸轮,粘贴有FBG的等强度悬臂梁与转速凸轮组成计数装置。基于风杯转速与风速呈线性关系建立了传感模型,根据中心波长变化次数进行计数,从而计算出风速,实现了对风场内风速实时监测。风洞试验表明:计数式FBG风速传感器的起动风速为0.9 m/s,线性度为6%,灵敏度为0.65 r/m。

  6. 基于脉冲宽度调制技术的超声波测风系统研究%Ultrasonic Anemometer System Based on PWM Techniques

    Institute of Scientific and Technical Information of China (English)

    吴宗玲; 闫连山; 曾德兵; 陈娟子

    2012-01-01

    The ultrasonic anemometer system design based on time-difference-method was presented, and the ways to improve the arriving time of ultrasonic signals were analyzed and that to achieve ultrasonic driving signal basing upon pulse width modulation ( PWM) proposed. Having the schemes with or without modulation techniques compared shows that the driving pulse with modulation techniques can greatly benefit the right judgment of the arriving time of the ultrasonic echo signal, the designed ultrasonic pulse driving scheme provides the good reference for the ultrasonic anemometer based on time-difference-method.%给出了时差法超声波测风系统的总体设计,分析了几种改善超声波信号到达时刻的方法.重点提出了一种基于脉冲宽度调制技术( PWM)的超声波驱动信号的具体实现方法.同时对采用和不采用调制技术两种方案进行了详细的对比分析,结果表明采用调制技术的驱动脉冲更有利于正确判决超声波回波信号的到达时刻.所设计的超声波脉冲驱动方案对基于时差法的超声波风速仪具有重要的参考价值.

  7. Maintenance of the Lightning Strike Failure of EL - type Contact Anemometer indicator%1EL型电接风向风速计指示器遭雷击故障维修

    Institute of Scientific and Technical Information of China (English)

    韦健; 梁继晗

    2011-01-01

    介绍了EL型电接风向风速计指示器电路工作原理,通过对EL型电接风向风速计指示器遭雷击故障分析,介绍指示器电源电路、风向指示电路的检修方法,为基层台站业务人员在工作中提供帮助。%Presented the theory of EL-type contact anemometer Indicator. Based on an analysis of the lightning strike failure of EL-type con- tact anemometer Indicator, introduced the maintenance methods of indicator circuit and wind direction indicator circuit help for the personnel of grass-roots unit in their work.

  8. A new calibration method of constant temperature hot wire anemometer%恒温热线风速仪的一种新型校准方法

    Institute of Scientific and Technical Information of China (English)

    姚惠元; 刘国政; 孙楠; 董军

    2013-01-01

    恒温热线风速仪作为一种风洞流场测量元件,在湍流脉动测速任务中发挥了重要作用。对热线风速仪的校准工作进行了研究,将B样条与递推最小二乘相结合,提出了一种新型校准方法。该方法选取具有低阶光滑特性的B样条函数进行逆向建模,并采用递推最小二乘的方法估计控制参数,有效地提高了校准精度和实时性。通过对实际风洞实验的数据分析,验证了提出的该校正方法的有效性,并表明其具有样本点少、校正精度高、简单实用等显著优点。%As a flow field measuring elements for wind tunnel,the constant temperature hot wire anemometer plays an im-portant role in the measurement of turbulent fluctuation task. The calibration of the hot wire anemometer is studied. Using the B-spline and recursive least squares as a combination,a new calibration method is proposed,which chooses B-spline function with low order smooth characteristics for reverse modeling,and estimates the control parameters using the method of recursive least squares. The method effectively improved the calibration accuracy and real-time. Through the analysis of wind tunnel experimen-tal data,the effectiveness of the correction method is validated. The experiment shows that it has the advantages of fewer sample points,higher correction accuracy,simple and useful.

  9. 风速风向仪设计中互谱插值算法的应用%Cross-spectral Interpolation Algorithm Based Designs of Anemometer

    Institute of Scientific and Technical Information of China (English)

    曲振林; 陈晓

    2014-01-01

    In order to solve the problems of the low measurement sensitivity of traditional anemometer, a new method based on the ultrasonic transit-time wind speed measurement was proposed. The cross-correlation algorithm was used to estimate the transit time difference, and to improve the estimation accuracy by cross-spectral interpolation. Results showed that com-pared with the cross-correlation algorithm, cross-spectral interpolation algorithm had more accurate delay estimation. According to the characteristics of FPGA device, the design of the entire measurement system were achieved with the use of Verilog HDL language programming, top-down design methods.%为解决传统风速风向仪测量精度不高的问题,设计了一种基于时差法的超声波风速测量仪。利用互相关算法实现超声波渡越时间差估计,并通过互谱插值来提高估计精度,仿真结果表明,与互相关算法相比,互谱插值算法对时间差的估计精度更高。根据FPGA器件特性,运用Verilog HDL语言编程,采用自顶向下的设计方法,实现了整个测量系统的设计。

  10. Effects of intracranial pressure on the pial microcirculation in rats studied by a fiber-optic laser-Doppler anemometer microscope.

    Science.gov (United States)

    Seki, J; Sasaki, Y; Oyama, T; Yamamoto, J

    1999-01-01

    The fiber-optic laser-Doppler anemometer microscope (FLDAM) developed in our laboratory was applied to measure red cell velocity in individual pial microvessels in rats to determine the effect of intracranial pressure (ICP) on the pial microcirculation. The red cell velocity and the vessel diameter of pial microvessels were measured through a closed cranial window at controlled values of ICP between 0 and 50 mmHg. As ICP increased from 0 to 50 mmHg, the average relative diameter of venules with respect to the diameter at an ICP of 5 mmHg decreased from 1.18 +/- 0.12 (mean +/- SD) to 0.74 +/- 0.08 and the average relative velocity increased from 0.80 +/- 0.20 to 1.83 +/- 0.42 monotonically. The changes in diameter and velocity of arterioles with ICP were small, and they were not significantly different from those values at an ICP of 5 mmHg except for the diameter at an ICP of 20 mmHg. The mean volume flow rates calculated assuming a circular vessel cross-section did not show any statistically significant change with ICP between 0 and 50 mmHg in both arterioles and venules, which supports the concept of autoregulation.

  11. Analysis of the air flow generated by an air-assisted sprayer equipped with two axial fans using a 3D sonic anemometer.

    Science.gov (United States)

    García-Ramos, F Javier; Vidal, Mariano; Boné, Antonio; Malón, Hugo; Aguirre, Javier

    2012-01-01

    The flow of air generated by a new design of air assisted sprayer equipped with two axial fans of reversed rotation was analyzed. For this goal, a 3D sonic anemometer has been used (accuracy: 1.5%; measurement range: 0 to 45 m/s). The study was divided into a static test and a dynamic test. During the static test, the air velocity in the working vicinity of the sprayer was measured considering the following machine configurations: (1) one activated fan regulated at three air flows (machine working as a traditional sprayer); (2) two activated fans regulated at three air flows for each fan. In the static test 72 measurement points were considered. The location of the measurement points was as follow: left and right sides of the sprayer; three sections of measurement (A, B and C); three measurement distances from the shaft of the machine (1.5 m, 2.5 m and 3.5 m); and four measurement heights (1 m, 2 m, 3 m and 4 m). The static test results have shown significant differences in the module and the vertical angle of the air velocity vector in function of the regulations of the sprayer. In the dynamic test, the air velocity was measured at 2.5 m from the axis of the sprayer considering four measurement heights (1 m, 2 m, 3 m and 4 m). In this test, the sprayer regulations were: one or two activated fans; one air flow for each fan; forward speed of 2.8 km/h. The use of one fan (back) or two fans (back and front) produced significant differences on the duration of the presence of wind in the measurement point and on the direction of the air velocity vector. The module of the air velocity vector was not affected by the number of activated fans.

  12. Analysis of the Air Flow Generated by an Air-Assisted Sprayer Equipped with Two Axial Fans Using a 3D Sonic Anemometer

    Directory of Open Access Journals (Sweden)

    Javier Aguirre

    2012-06-01

    Full Text Available The flow of air generated by a new design of air assisted sprayer equipped with two axial fans of reversed rotation was analyzed. For this goal, a 3D sonic anemometer has been used (accuracy: 1.5%; measurement range: 0 to 45 m/s. The study was divided into a static test and a dynamic test. During the static test, the air velocity in the working vicinity of the sprayer was measured considering the following machine configurations: (1 one activated fan regulated at three air flows (machine working as a traditional sprayer; (2 two activated fans regulated at three air flows for each fan. In the static test 72 measurement points were considered. The location of the measurement points was as follow: left and right sides of the sprayer; three sections of measurement (A, B and C; three measurement distances from the shaft of the machine (1.5 m, 2.5 m and 3.5 m; and four measurement heights (1 m, 2 m, 3 m and 4 m. The static test results have shown significant differences in the module and the vertical angle of the air velocity vector in function of the regulations of the sprayer. In the dynamic test, the air velocity was measured at 2.5 m from the axis of the sprayer considering four measurement heights (1 m, 2 m, 3 m and 4 m. In this test, the sprayer regulations were: one or two activated fans; one air flow for each fan; forward speed of 2.8 km/h. The use of one fan (back or two fans (back and front produced significant differences on the duration of the presence of wind in the measurement point and on the direction of the air velocity vector. The module of the air velocity vector was not affected by the number of activated fans.

  13. An ultrasonic anemometer based on DSP and FPGA%基于FPGA和DSP的超声波风向风速测量系统

    Institute of Scientific and Technical Information of China (English)

    丁向辉; 李平

    2011-01-01

    本文研究了数字化超声风速测量系统,提出并实现了完整的系统设计方案.该方案的核心足基于现场可编程门阵列(FPGA)和数字信号处理器(DSP)的硬件系统架构和基于包络重心法的信号处理算法.该设计可实现超声信号的高速数据采集和复杂的信号处理算法.测试结果表明所实现的超声风速测量系统具有体积小、反应速度快、抗干扰能力强和分辨率高等优点,且具有成本优势,并保持较低的功耗.%A digital ultrasonic anemometer system is proposed in this paper.A new design scheme is studied and realized.The key elements of this new scheme are DSP and FPGA and gravity center of the envelop estimation method.The designed system supports very high sample rates and more complicated digital signal processing algorithms.Experiments show that the proposed system has a small size, a fast response speed, and a high resolution, and is more robust in noisy environments.Besides, the system has cost effective advantages while maintaining low power consumption.

  14. 舰载风速仪测量误差与安装位置的关系研究%The relationship between the measurement error of shipborne anemometer and its installation location

    Institute of Scientific and Technical Information of China (English)

    郜冶; 谭大力; 李海旭; 王金玲; 刘长猛

    2014-01-01

    It is significant to research the relationship between the measurement error of a shipborne anemometer and its installation location because the ship wave motions as well as the observation location to a certain extent are both influenced by the measurement accuracy. By the CFD calculation software FLUENT13.0 with a reasonably sim⁃plified physical model, an appropriate mathematical model, high quality meshes, and suitable boundary conditions are used to calculate the anemometer airflow field under different conditions. The results showed that the anemome⁃ter measurement error is generally large for the existing location and the anemometer measurement error is signifi⁃cantly higher under the condition of low wind speed and high ship speed. The variation law between the wind angle and speed measurement error and its locations, as well as the influence degree of ship body to the anemometer measurement accuracy is given. The results also showed that the ship body had a great impact on the anemometer near flow field. In the far flow field its impact can be ignored when doing the qualitative analysis. This paper pro⁃vides an important basis for getting more reasonable installation location and improving the measurement accuracy of anemometer.%船体的运动姿态以及观测点位置的差别等均会对舰载风速仪的测量精度产生一定程度的影响,因此研究舰载风速仪测量误差与其安装位置之间的关系具有重要意义。以大型CFD计算软件FLUENT13.0为平台,合理简化物理模型,建立恰当的数学模型,划分高质量网格,赋予模型合适的边界条件对不同工况下风速仪周围的气流场进行了计算分析。研究表明风速仪在现有安装位置测量误差较大,低风速高船速时风速仪的测量误差明显较高。还给出了风向角及风速值测量误差随安装位置的变化规律,以及船体本身对风速仪测量精度的影响程度,为更加合理

  15. Design of Ultrasonic Anemometer Based on ZigBee for Wind Power%基于ZigBee的风力发电超声波风速风向仪设计

    Institute of Scientific and Technical Information of China (English)

    辛晓帅; 周康

    2012-01-01

    根据风力发电系统的应用要求,设计了一种基于ZigBee通信方式的超声波风速风向仪.介绍了时差法超声波风速风向仪的基本原理,以数字信号处理器TMS320F28335为数据处理单元实现风速风向信号的计算;采用无线通信模块CC2530实现与数据处理单元之间的RS - 232方式通信和与风力发电控制系统间的无线通信;介绍了采用超声波风速风向仪进行风力发电系统偏航控制的控制原理.实际应用表明:在风力发电系统中,采用无线超声波风速风向仪具有较高的采样精度和灵敏度,且易于安装及维护.%A ultrasonic anemometer based on ZigBee was designed according to the requirement of wind power. The time difference measurement method was introduced,and digital signal processor TMS320F28335 was used to calculate the wind speed and wind direction. The CC2530 was used to communicate with TMS320F2833 through RS -232 and communicate with wind turbine control u-nit through ZigBee. A control principle was designed for the yawing of the wind turbine by using ultrasonic anemometer. Practical application shows that it's more convenient for the installation and maintenance of the wireless ultrasonic anemometer,the sample rate and response rate of wind speed and direction are improved by using wireless ultrasonic anemometer in wind power.

  16. Design of ultrasonic wave anemometer with high precision based on ARM + CPLD%基于ARM+CPLD的高精度超声波风速仪的设计

    Institute of Scientific and Technical Information of China (English)

    吴宗玲; 闫连山; 曾德兵; 陈娟子

    2012-01-01

    The principle of measurement of wind speed and direction using ultrasonic wave time difference method is introduced followed by related algorithms, the design of ultrasonic wave anemometer based on ARM +CPLD is described in details. In addition, an effective algorithm dealing with the average wind direction problems near 0° (360°) is proposed. An absolute wind speed measurement model is provided using a baroceptor for practical wind measurement applications. The designed ultrasonic wave anemometer has important reference application value in environmental monitoring and wind power generation.%分析了运用超声波时差法测量风速风向的基本原理,介绍了风速风向的相关算法,重点给出了基于ARM +CPLD的超声波风速风向仪原型设计.同时提出了一种处理0°(360°)附近平均风向问题的算法,结合实际运用(风力发电)给出了一种运用气压传感器进行绝对风速测量的理论模型.所设计的超声波风速风向仪对环境监测和风力发电等具有重要的参考应用价值.

  17. Study on Identification of Error for the NC Machine Tools Based on Laser Doppler Anemometer%基于激光多普勒仪的数控机床误差辨识

    Institute of Scientific and Technical Information of China (English)

    甘彬; 刘洋; 赵宇

    2013-01-01

    In response to laser Doppler anemometer characteristics of high precision linear displacement measurement of CNC machine tools, this paper introduced the use of laser Doppler anemometer on the NC machine tool error detection and identification method, explained the identification principle in detail and set up the method of error detection model. In order to reduce the machine error, we provide measurement method and basis of the compensation.%针对激光多普勒仪对数控机床线位移测量精度高的特点,介绍了利用激光多普勒仪对数控机床进行误差检测和辨识的方法,阐述了该方法的几何误差辨识原理,并建立了基于该方法的误差检测数学模型.为减小机床误差提供了测量方法和补偿依据.

  18. Aerodynamic characteristics of anemometer cups

    Science.gov (United States)

    Brevoort, M J; Joyner, U T

    1934-01-01

    The static lift and drag forces on three hemispherical and two conical cups were measured over a range of angles of attack from 0 degrees to 180 degrees and a range of Reynolds Numbers from very small up to 400,000. The problems of supporting the cup for measurement and the effect of turbulence were also studied. The results were compared with those of other investigators.

  19. 空气湿度对矿用低速风洞的风速表检定结果影响%Analysis of air temperature and humidity on the impact of mining anemometer with a low-speed wind tunnel verification results

    Institute of Scientific and Technical Information of China (English)

    陈权; 张于; 卢从俊

    2013-01-01

      分析矿用低速风洞的工作原理,研究目前所使用的检定规程JJG(煤炭)01—96《矿用风速表》,发现湿度的变化影响空气密度的变化,而空气密度的改变直接影响风速表的检定结果。忽略了湿度对空气密度的影响,会影响风速表检定结果的准确性。%  This paper first introduces the current China's mining anemometer verification the basic situation, detailed analysis of the working principle of the mine low-speed wind tunnel. Based on the principle of this kind of work, we ware carefully studied mining anemometer VRof, The currently used VRof is JJG (coal) 01-96《mining anemometer》VRof, this statute ignored the impact of humidity on the verification results. In this paper, the effects of humidity study. The analysis found that changes in humidity will affect the changes in air density, and the air density changes directly affect the verification results of the anemometer. Ignoring the influence of the humidity of the air density will affect the accuracy of the anemometer verification results.

  20. The influence of sandstorm on the measured results of ultrasonic anemometer%风沙环境对超声风速仪测量结果的影响

    Institute of Scientific and Technical Information of China (English)

    李兴财

    2013-01-01

    超声风速仪由于其在风速、风向测量方面的卓越性能被引入风沙物理学及沙尘暴研究中以获得相关风场信息.然而,对其在风沙环境下测量结果的准确性目前并无文献资料讨论.通过对超声风速仪测量原理及超声波在含颗粒物介质中传播速度变化的理论分析,讨论了沙尘暴环境下沙尘颗粒物体积浓度对超声风速仪测量结果的影响.数值计算结果表明,当沙尘颗粒体积分数超过50%时,超声风速仪测量值的相对误差超过10%,且随着颗粒物体积分数的增加,其测量误差呈指数形式递增.这一结果对于风沙环境中超声风速仪的正确使用具有非常重要的参考价值.%Due to its superior performance in the measurement of wind speed and direction,the ultrasonic anemometer is introduced into the blown sand physics and sandstorms research to get the relevant wind field information.However,the measurement accuracy in a sandy environment has no literature discussion yet.The principle of the ultrasonic anemometer and the velocity changes of ultrasonic wave propagation in the particle contained media are firstly analyzed.Then the influence of sand or dust particle concentration on the measurement results of ultrasonic anemometer is discussed.The numerical results show that when the dust particle volume fraction is over 50%,the relative error of the equipment measured value is over 10%.And the error increases exponentially with the particle volume fraction.

  1. Design on starting threshold of wind velocity calibration system for cup anemometer%杯式风速传感器启动风速校验系统的设计

    Institute of Scientific and Technical Information of China (English)

    行鸿彦; 李阳

    2015-01-01

    杯式风速传感器是目前应用最为广泛的风速传感器,其启动风速取决于它的启动力矩,不良的轴承会导致传感器的启动力矩比正常值偏高,从而影响其测量的准确性。为此设计开发了杯式风速传感器启动风速检验系统,该系统以应变式力传感器为测力元件,MSP430低功耗单片机作为主控芯片,采用高精度 AD 转换芯片以及比例式测量技术保证了系统的精度,辅以光电开关实现对杯式风速传感器启动力矩的测量,最终达到校验其启动风速的目的。本系统功耗小,便于携带,适用于杯式风速传感器启动力矩(启动风速)的现场校验。%Cup anemometer is one of the most widely used wind speed sensors.The starting threshold of wind velocity is determined by the starting torque of the sensor.Bad bearings will cause higher torque values than normal,which can effect the accuracy of the instrument.The system is designed with strain gauge force transducer.The low-power MCU MSP430 is used as the host controller.To ensure the precision of the whole system,high-precision AD and proportion measuring techniques are used. Besides,a photoelectrical switch is also adopted to measure the instantaneous torque of cup anemometer in the starting moment so as to get the starting threshold of wind velocity.The system is portable and low in power consumption so that it can be used in the field calibration of cup anemometer.

  2. Design and implementation of concave reflector based ultrasonic anemometer system%基于凹面反射的超声风速测量系统设计与实现

    Institute of Scientific and Technical Information of China (English)

    崔国恒; 赵金超; 曹可劲

    2014-01-01

    时差法是超声风速风向测量系统的基本方法。在介绍时差测量原理的基础上,分析了系统测量误差的来源;构建了增大测量范围的凹面反射模型;结合该模型,在系统结构、电路系统、控制流程及数据处理算法等方面进行了全面的设计和实现,并制成了原理样机。风洞试验结果表明,凹面反射结构可以增加系统的测量范围,提高大风条件下测量数据的稳定性。原理样机具有体积小、可靠性高、测量范围大的优点,已在风力发电方面获得了实际应用,并取得了较好的应用效果。%Time difference measurement method has been extensively used in ultrasonic anemometer system. Based on the principle of the time difference method of measuring the speed and direction of wind, the cause of the measurement error in the measuring system is analyzed. In this paper a concave reflector model is adopted to increase the measuring range in contrast with the plane reflection model. With this model, the corresponding structure design, circuit design, control process and signal processing methods of the ultrasonic anemometer system are discussed, and a prototype system is implemented. The experimental results indicate that the ultrasonic anemometer system has broad measure-ment range and high stability in high wind speeds. Besides, the prototype system has the advantages in small size, high resolution and reliability, which has been used in wind power generation and got good effects.

  3. Analysis of offshore anemometer tower in deep water by finite element method%大水深离岸型海上测风塔整体有限元分析

    Institute of Scientific and Technical Information of China (English)

    周颖; 吴海明; 齐志诚

    2015-01-01

    我国目前没有可直接运用于大水深、工程环境复杂的海上测风塔的设计技术标准. 根据我国《港口工程地基规范》及相关工程技术标准,利用通用有限元结构软件分析了测风塔结构受力;同时依据国际通用的美国石油行业《海上固定平台入级与建造规范》(即API RP 2A规范),利用海工结构有限元分析软件对测风塔进行了结构分析. 计算分析内容包括:测风塔多种设计荷载、多种设计工况、关键节点位移、杆件内力和疲劳分析等. 两种计算结果基本一致,均能满足相应规范要求,说明所选取的设计参数较为合理,相关的工程设计经验可为类似工程及海上风电场建设提供参考借鉴.%In China, there is no technical standard for the engineering design of wind measurement tower in deep sea water with complicated engineering condition. To ensure the safety and reliability of anemometer tower of offshore wind power plants, general FEM software is employed to analyze the structural stress of anemometer tower under the guidance of Chinese Technical Standard for Port Engineering firstly;then a professional marine structure FEM software is employed to conduct the structure anal-ysis for the anemometer tower based on the APIRP 2A, a USA petroleum industry standard. The structure analysis work consists of multiple designed loading, multiple cases, key nodes displacement, element internal force and fatigue analysis. The two calcu-lation results show consistence and both satisfy the relevant requirements specified in the technical standards. The parameters a-dopted in design are reasonable and the experience in the design of this project can provide reference for the design and construc-tion of similar offshore wind power plants in future.

  4. 二维超声波风速风向传感器风向信号修正方法%Correction method for wind direction signal measured by 2D ultrasonic anemometer

    Institute of Scientific and Technical Information of China (English)

    李静海; 曾明; 张小内

    2016-01-01

    针对二维超声波风速风向传感器输出的风向信号普遍存在风向角瞬变的问题,研究了产生风向角瞬变现象的原因,并提出了一种基于幅值—符号分解的风向修正算法。理论分析和实验结果表明:风向信号中的风向角瞬变是由传感器的量程限制造成的;基于幅值—符号分解的风向修正算法能在不改变风向角所表征的方位特征的前提下消除风向角瞬变。%Aiming at problem that wind angle transient is common in wind signal for 2D ultrasonic anemometer, causes of this problem is studied,and a correction algorithm based on magnitude/ sign decomposition is proposed. Theoretical analysis and experimental results show that the wind angle transient is arised by range limits of sensor, and the correction algorithm based on magnitude/ sign decomposition can eliminate this problem without changing orientative feature represented by wind angle.

  5. 基于三维超声风速风向仪的高精度数据测量方法%High Precision Data Measurement of Wind Speed and Direction Based on Three-Axis Ultrasonic Anemometer

    Institute of Scientific and Technical Information of China (English)

    吴有恒; 荣海春

    2015-01-01

    Three‐Axis ultrasonic anemometer is very suitable for the environment monitor demand of teth‐ered aerostat and airship because of its high precision ,fast answer ,perfect function and agile configura‐tion .This paper proposes a detection design about wind speed and direction based on the sensor ,where the course of data collecting and processing is described emphatically.This method has been used successfully in a type of tethered aerostats .%三维超声风速风向仪具有测量精度高,响应速度快,功能全面,配置灵活等特点,非常适合系留气球及飞艇等浮空器对大气环境参数监测的要求。提出了基于该型传感器的风速风向检测系统的设计方法,重点介绍了风速风向数据的采集和处理过程。该方法已在某型系留气球系统中得到成功应用。

  6. Wireless Ultrasonic Anemometer Based on Direct Time Difference Method%采用直接时差法的无线超声波风速风向仪设计

    Institute of Scientific and Technical Information of China (English)

    周康; 辛晓帅

    2011-01-01

    采用直接时差法,以TMS320F2812为控制单元控制超声波的发射与接收,实现了超声波风速风向仪的设计。该超声波风速风向仪利用模拟开关设计驱动电路,减少了电磁干扰对电路的影响;利用限幅、放大、正弦脉冲转换的方法设计接收电路,减少了A/D转换波动对信号捕获以及时间点判断的影响。%An ultrasonic anemometer is designed using direct time difference method. TMS320F2812 is used as the control unit for trans- mitting and receiving ultrasonic. Driving circuit is implemented using analog switches, reducing the impact of electromagnetic interference in the circuit. Receiving circuit is designed by using limiting amplification sine pulse transfer, reducing the effect of A/D conversion fluc- tuations on signal acquisition and time point estimation.

  7. Sensor Tip Optimization for a Thermal Anemometer for Determining Convection Intensity in Quench Baths%测定淬火槽对流强度的热流速仪探头的优化设计

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Due to the occurrence of complex fluid flow patterns in a quench tank which will significantly impact hardening results,it is important to develop a compact flow measuring device.A typical quench process involves immersion of austenitized steel into a quench bath which affects the circulation of the fluid and results in non-uniform flow and thermal striations in the quenchant.This non-uniformity of fluid flow patterns therefore results in variations of heat transfer and subsequent inconsistent hardening of the parts.In this paper,the systematic optimization of the tip of a thermal anemometer used to measure flow rates in a quench tank are reviewed.%淬火槽中复杂的液流形态会明显影响淬硬结果,因此开发一套结构紧凑的液流测量装置就显得很重要了.一个典型的淬火过程包括把已奥氏体化了的钢浸没在淬火槽中,这一过程势必影响液流的循环,使其形成不均匀的液流和热波动,由此而引起传热变化,导致零件的不均匀淬火.本文介绍了用于测量淬火槽中液流速率的热风仪探头的系统优化设计.

  8. 基于检定环境对风速表标准值影响的研究%Study on verification environment based on the influence of anemometer standard value

    Institute of Scientific and Technical Information of China (English)

    刘宇; 武春爱; 张佳佳; 蒋涛; 于平

    2016-01-01

    为明确风速传感器在检定过程中受到检定环境如温度、湿度和气压所带来的影响,依据《JJG431-2014轻便三杯风向风速表检定规程》对轻便三杯风向风速传感器进行检定,通过标准风速计算公式分析空气温度、湿度和气压检定前后的变化对检定结果的影响,运用加权计算方法计算得出检定过程中温度、湿度和气压各自所占权重,经过实验验证比对,结果表明通过分析研究温、湿度和气压对于标准风速值的影响,使风速传感器检定的准确性得到显著提高,减小了测量不确定度.%In order to clarify the influence of temperature, humidity and air pressure on the verification environment for the wind speed sensor, According to "JJG431-2014 Portable 3-cup anemometers" verification the speed sensors, through the formula for computing the standard wind speed analysis of air temperature, humidity and air pressure changes before and after verification on the result of test, the calculated by weighted calculation method verification of temperature, humidity and air pressure in the process of their weight, through experiment, the experimental results show that through the analysis and research on the influence of temperature, humidity and air pressure values on the wind speed standard , the wind speed sensor calibration accuracy is increased significantly, reduce the uncertainty of measurement.

  9. Measurement of the local void fraction in two-phase air-water flow with a hot-film anemometer; Mesure du taux de vide local en ecoulement diphasique eau-air par un anemometre a film chaud

    Energy Technology Data Exchange (ETDEWEB)

    Delhaye, J. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1968-07-01

    The experimental knowledge of the local void-fraction is basic for the derivation of the constitutive equations of two-phase flows. This report deals with measurements of the local void-fraction based on the use of a constant temperature hot-film anemometer associated with a multichannel analyser. After determining the void-fraction profile along a diameter of a vertical pipe (40 mm I.D.), in which air and water flow upwards, we compare the void-fraction averaged over the diameter with the average value measured directly by a {gamma}-ray method. Two runs were made in bubble flow and a third in slug flow. The two methods give results in a good agreement especially for bubble flow. The void-fraction averaged over the cross-section was also calculated from the different profiles and compared in a good manner with the experimental results of R. ROUMY. For bubble flow we verified the theory of S.G. BANKOFF about the shape of the void-fraction profiles. (author) [French] Nous proposons une methode de mesure du taux de vide local a en ecoulement diphasique, basee sur l'emploi d'un anemometre a film chaud a temperature constante dont on etudie la repartition du signal en amplitude dans un analyseur multicanaux. Ayant trace un profil de taux de vide local suivant un diametre d'une conduite verticale de section circulaire parcourue par un ecoulement ascendant d'eau et d'air, nous avons compare la moyenne de {alpha} sur ce diametre a la valeur obtenue par une methode d'absorption de rayons {gamma}. Les essais ont ete faits en ecoulements a bulles et a bouchons. Les deux methodes donnent des resultats concordants en particulier pour les ecoulements a bulles. Le taux de vide moyenne dans la section, calcule a partir des differents profils, a egalement ete compare avec succes aux resultats experimentaux de R. ROUMY. Dans l'etude de la structure radiale des ecoulements a bulles, nous avons verifie l'hypothese de S.G. BAJMKOFF. (auteur)

  10. Microscale out-of-plane anemometer

    Science.gov (United States)

    Liu, Chang (Inventor); Chen, Jack (Inventor)

    2005-01-01

    A microscale out-of-plane thermal sensor. A resistive heater is suspended over a substrate by supports raised with respect to the substrate to provide a clearance underneath the resistive heater for fluid flow. A preferred fabrication process for the thermal sensor uses surface micromachining and a three-dimensional assembly to raise the supports and lift the resistive heater over the substrate.

  11. Micro-sensor thin-film anemometer

    Science.gov (United States)

    Sheplak, Mark (Inventor); McGinley, Catherine B. (Inventor); Spina, Eric F. (Inventor); Stephens, Ralph M. (Inventor); Hopson, Jr., Purnell (Inventor); Cruz, Vincent B. (Inventor)

    1996-01-01

    A device for measuring turbulence in high-speed flows is provided which includes a micro-sensor thin-film probe. The probe is formed from a single crystal of aluminum oxide having a 14.degree. half-wedge shaped portion. The tip of the half-wedge is rounded and has a thin-film sensor attached along the stagnation line. The bottom surface of the half-wedge is tilted upward to relieve shock induced disturbances created by the curved tip of the half-wedge. The sensor is applied using a microphotolithography technique.

  12. Testing of the anemometer circuit: Data report

    Science.gov (United States)

    Moen, Michael J.

    1992-01-01

    The following text discusses results from the electronic step testing and the beginning of velocity step testing in the shock tube. It should be kept in mind that frequency response is always measured as the time from the beginning of the event to the minimum (positive inflection) of the 'bucket' that immediately follows the response. This report is not a complete account of the results from square wave testing. Some data is still in the process of being analyzed and efforts are being made to fit the data to both Freymuth's third order theory and modelled responses from SPICE circuit simulation software.

  13. Vortex Anemometer Using MEMS Cantilever Sensor

    CERN Document Server

    Zylka, P; Zylka, Pawel; Modrzynski, Pawel

    2010-01-01

    This paper presents construction and performance of a novel hybrid microelectromechanical system (MEMS) vortex flowmeter. A miniature cantilever MEMS displacement sensor was used to detect frequency of vortices development. 3-mm-long silicon cantilever, protruding directly out of a trailing edge of a trapezoidal glass-epoxy composite bluff body was put into oscillatory motion by vortices shed alternately from side surfaces of the obstacle. Verified linearmeasurement range of the device extended from 5 to 22 m/s; however, it could be broadened in absence of external 50-Hz mains electrical interfering signal which required bandpass frequency-domain digital sensor signal processing. The MEMS vortex sensor proved its effectiveness in detection of semilaminar airflow velocity distribution in a 40-mm-diameter tubular pipe.

  14. Arkansas' Anemometer Loan Program

    Energy Technology Data Exchange (ETDEWEB)

    Fernando Vego

    2012-10-11

    The measurement campaign had one year duration from 04/01/2011 to 03/31/2012 and was taken at 20m and 34m with NRG instrumentation. The data was analyzed weekly to check inconsistencies and validity and processed using Excel, Flexpro and Windographer standard Edition Version 2.04. The site analyzed is located in the Waldron, Arkansas in Scott County. It is an open site for most of the direction sectors with immediate roughness class of 1.5. It has seasonally directional winds, of which the most energetic come from the southern direction. The vertical wind profile shows moderate wind shear that varies by season as well.

  15. Reviews Book: Voyage to the Heart of the Matter: The ATLAS Experiment at CERN Equipment: SEP Spectroscope Books: Quantum Gods / The Universe Places to visit: The Royal Institution of Great Britain Book: What is this Thing Called Science? Book: Don't be Such a Scientist: Talking Substance in the Age of Style Equipment: La Crosse Anemometer Book: Wonder and Delight Web Watch

    Science.gov (United States)

    2010-05-01

    WE RECOMMEND SEP Spectroscope Flatpacked classroom equipment for pupils aged 10 and over Quantum Gods Book attacks spiritualism and religion with physics The Universe Study of whether physics alone can explain origin of universe La Crosse Anemometer Handheld monitor is packed with useful features Wonder and Delight Essays in science education in honour of Eric Rogers WORTH A LOOK Voyage to the Heart of the Matter: The ATLAS Experiment at CERN Pop-up book explains background to complex physics The Royal Institution of Great Britain RI museum proves interesting but not ideal for teaching What is this Thing Called Science? Theory and history of science in an opinionated study Don't be Such a Scientist: Talking Substance in the Age of Style Explanation of how science is best communicated to the public WEB WATCH Particle physics simulations vary in complexity, usefulness and how well they work

  16. 基于机舱风速数据的风电场弃风电量计算方法研究%Study on Energy Loss Calculation During Wind Power Curtailment Based on Wind Speed Measured by Turbine Nacelle Anemometers

    Institute of Scientific and Technical Information of China (English)

    姜文玲; 冯双磊; 孙勇; 王勃; 汪宁渤; 郭凌旭

    2014-01-01

    为准确评估风电场弃风时段的电量损失,提出了一种新的风电场理论功率与弃风电量计算方法-机舱风速法。该方法基于风电机组正常运行时段的输出功率与机舱风速计的测量风速建立映射关系,再应用到弃风时段,计算风电场的理论功率与弃风电量。为研究该方法的可靠性,分析了仪器测量偏差、风机尾流波动性、开停机状态对理论功率计算结果的影响,并给出了开、停机状态下机舱测量风速的换算方法。采用风电场实测数据对机舱风速法进行了验证,验证结果显示机舱风速法计算的理论功率的相关性系数平均为0.9960,均方根误差平均为1.87%,理论电量误差平均为0.68%。与已有方法相比,机舱风速法计算精度高,便于区分电量损失来源,能针对不同开机方案进行灵活设置。机舱风速法不需要建立测风塔,但如能引入测风塔数据修正机舱风速,有可能进一步提升计算精度。%To accurately assess the energy loss of wind farm during wind power curtailment, a new method to calculate theoretical power of wind farm and energy loss due to wind power curtailment, which is called nacelle wind speed method, is proposed. A mapping relation based on output power of wind power generating unit under normal operation and the wind speed measured by turbine nacelle anemometers is established, and using the established relation to the time-interval of wind power curtailment, the theoretical power of wind farm and the energy loss due to wind power curtailment are calculated. To research the reliability of the proposed method, the impacts of measured deviation of instruments, the fluctuation of the turbine’s wake and the operating status of turbines on calculation result of theoretical power are analyzed, and a conversion method of wind speed measured in turbine nacelles under the conditions of being operated and being shut down of wind

  17. Three-dimensional Doppler anemometer using a holographic optical element.

    Science.gov (United States)

    Schneider, F; Windein, W

    1988-11-01

    A new simple 3-D laser Doppler system has been developed for simultaneous measurement of the instantaneous velocity vector of a scattering particle. The system is based on the reference beam method. It uses a hologram to generate the reference beams. Only one laser operating in single mode is required as the light source. The system has been tested by measuring all the components of the Reynolds stress tensor in a round cold air jet. The results are presented.

  18. Laser induced fluorescence photobleaching anemometer for microfluidic devices.

    Science.gov (United States)

    Wang, G R

    2005-04-01

    We have developed a novel, non-intrusive fluid velocity measurement method based on photobleaching of a fluorescent dye for microfluidic devices. The residence time of the fluorescent dye in a laser beam depends on the flow velocity and approximately corresponds to the decaying time of the photobleaching of the dye in the laser beam. The residence time is inversely proportional to the flow velocity. The fluorescence intensity increases with the flow velocity due to the decrease of the residence time. A calibration curve between fluorescence intensity and known flow velocity should be obtained first. The calibration relationship is then used to calculate the flow velocity directly from the measured fluorescence intensity signal. The new method can measure the velocity very quickly and is easy to use. It is demonstrated for both pressure driven flow and electroosmotic flow.

  19. Method of Forming Micro-Sensor Thin-Film Anemometer

    Science.gov (United States)

    Sheplak, Mark (Inventor); McGinley, Catherine B. (Inventor); Spina, Eric F. (Inventor); Stephens, Ralph M. (Inventor); Hopson, Purnell, Jr. (Inventor); Cruz, Vincent B. (Inventor)

    2000-01-01

    A device for measuring turbulence in high-speed flows is provided which includes a micro- sensor thin-film probe. The probe is formed from a single crystal of aluminum oxide having a 14 deg half-wedge shaped portion. The tip of the half-wedge is rounded and has a thin-film sensor attached along the stagnation line. The bottom surface of the half-wedge is tilted upward to relieve shock induced disturbances created by the curved tip of the half-wedge. The sensor is applied using a microphotolithography technique.

  20. Design and Calibration of an Inexpensive Digital Anemometer

    Science.gov (United States)

    Hernandez-Walls, R.; Rojas-Mayoral, E.; Baez-Castillo, L.; Rojas-Mayoral, B.

    2008-01-01

    An inexpensive and easily implemented device to measure wind velocity is proposed. This prototype has the advantage of being able to measure both the speed and the direction of the wind in two dimensions. The device utilizes a computational interface commonly referred to as a "mouse." The mouse proposed for this prototype contains an…

  1. Cantilever anemometer based on a superconducting micro-resonator: application to superfluid turbulence.

    Science.gov (United States)

    Salort, J; Monfardini, A; Roche, P-E

    2012-12-01

    We present a new type of cryogenic local velocity probe that operates in liquid helium (1 K < T < 4.2 K) and achieves a spatial resolution of ≈ 0.1 mm. The operating principle is based on the deflection of a micro-machined silicon cantilever which reflects the local fluid velocity. Deflection is probed using a superconducting niobium micro-resonator sputtered on the sensor and used as a strain gauge. We present the working principle and the design of the probe, as well as calibration measurements and velocity spectra obtained in a turbulent helium flow above and below the superfluid transition.

  2. Influence of red blood cell concentrations on the measurement of turbulence using hot-film anemometer.

    Science.gov (United States)

    Sallam, A M; Hwang, N H

    1983-11-01

    Measurement of local velocity fluctuations was made with an L-shaped conical hot-film probe in a submerged circular jet. The experiment was carried out in solutions of washed human red blood cells (RBC) in a phosphate buffer solution (PBS), at hematocrit concentrations (Ht percent) of 10, 19, 29, and 38 percent. The viscosity of the testing solutions was kept at 3.2 c.p. by adding proper amount of dextran. The experiment was conducted at Reynolds numbers (NR) 674, 963, 1255 and 1410, based on the jet exit velocity and exit diameter. Statistical analyses were performed on the recorded instantaneous velocity signals to obtain the root-mean-square (rms) values, the probability density functions (PDF) and the power spectral density functions (PSDF) of the signals. Within the range tested, we noticed an incidental rise in rms values at 19 to 29 Ht percent for NR = 963 similar to those reported earlier in the literature. Further analyses using PDF and PSDF, however, showed neither a trend nor any physical significance of this rise. Based on the analyses of both the PDF and the PSDF, we believe that the incidental rise in rms value can be partially attributed to the high spikes registered by the probe in a high RBC concentrations fluid flow. The bombardment of RBC on the probe thermal boundary layer may cause a characteristic change in the probe response to certain flow phenomenon, at least within the Reynolds number range used in this study.(ABSTRACT TRUNCATED AT 250 WORDS)

  3. Note: Improving long-term stability of hot-wire anemometer sensors by means of annealing.

    Science.gov (United States)

    Lundström, H

    2015-08-01

    Annealing procedures for hot-wire sensors of platinum and platinum-plated tungsten have been investigated experimentally. It was discovered that the two investigated sensor metals behave quite differently during the annealing process, but for both types annealing may improve long-term stability considerably. Measured drift of sensors both without and with prior annealing is presented. Suggestions for suitable annealing temperatures and times are given.

  4. Laser Doppler anemometer measurements of pulsatile flow in a model carotid bifurcation.

    Science.gov (United States)

    Ku, D N; Giddens, D P

    1987-01-01

    Hemodynamics at the human carotid bifurcation is important to the understanding of atherosclerotic plaque initiation and progression as well as to the diagnosis of clinically important disease. Laser Doppler anemometry was performed in a large scale model of an average human carotid. Pulsatile waveforms and physiologic flow divisions were incorporated. Disturbance levels and shear stresses were computed from ensemble averages of the velocity waveform measurements. Flow in the common carotid was laminar and symmetric. Flow patterns in the sinus, however, were complex and varied considerably during the cycle. Strong helical patterns and outer wall flow separation waxed and waned during each systole. The changing flow patterns resulted in an oscillatory shear stress at the outer wall ranging from -13 to 9 dyn cm-2 during systole with a time-averaged mean of only -0.5 dyn cm-2. This contrasts markedly with an inner wall shear stress range of 17-50, (mean 26) dyn cm-2. The region of transient separation was confined to the carotid sinus outer wall with no reverse velocities detected in the distal internal carotid. Notable disturbance velocities were also time-dependent, occurring only during the deceleration phase of systole and the beginning of diastole. The present pulsatile flow studies have aided in identifying hemodynamic conditions which correlate with early intimal thickening and predict the physiologic level of flow disturbances in the bulb of undiseased internal carotid arteries.

  5. Evaluation of Tower Shadowing on Anemometer Measurements at Los Alamos National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Bruggeman, David Alan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-06-14

    The objective of this study is to evaluate the effect of tower shadowing from the meteorology towers at LANL during 2014. This study is in response to the Department of Energy Meteorological Coordinating Council visit in 2015 that recommended an evaluation of any biases in the wind data introduced by the tower and boom alignment at all meteorology towers.

  6. Measurement of gas flow velocity: anemometer with a vibrating hot wire.

    Science.gov (United States)

    Kiełbasa, Jan

    2010-01-01

    I propose a new method to measure velocity of a gas flow, which utilizes the time derivative of the voltage observed on a vibrating hot-wire sensor. The wire vibrates with an amplitude a and a frequency f, and is kept perpendicular to the gas flow direction in the plane containing the flow velocity vector v(g). When the parameters of vibrations are tuned, the number of zeros per vibration period of the hot-wire voltage function changes. I demonstrate that at the point of change, the unknown gas velocity is directly expressed by the parameters of vibrations v(g)=2pifa. Therefore, the velocity can be measured without any prior calibration of the hot-wire speed-voltage curve and the method can be used for gases of slowly changing temperature or composition.

  7. Note: Improving long-term stability of hot-wire anemometer sensors by means of annealing

    Energy Technology Data Exchange (ETDEWEB)

    Lundström, H., E-mail: hans.lundstrom@hig.se [Department of Building, Energy and Environmental Engineering, University of Gävle, SE-801 76 Gävle (Sweden)

    2015-08-15

    Annealing procedures for hot-wire sensors of platinum and platinum-plated tungsten have been investigated experimentally. It was discovered that the two investigated sensor metals behave quite differently during the annealing process, but for both types annealing may improve long-term stability considerably. Measured drift of sensors both without and with prior annealing is presented. Suggestions for suitable annealing temperatures and times are given.

  8. Hot Wire Anemometer Turbulence Measurements in the wind Tunnel of LM Wind Power

    DEFF Research Database (Denmark)

    Fischer, Andreas

    Flow measurements were carried out in the wind tunnel of LM Wind Power A/S with a Dantec Streamline CTA system to characterize the flow turbulence. Besides the free tunnel flow with empty test section we also investigated the tunnel flow when two grids with different mesh size were introduced dow...

  9. Measurement of air velocity in animal occupied zones using an ultrasonic anemometer

    NARCIS (Netherlands)

    Wagenberg, van A.V.; Leeuw, de M.T.J.

    2003-01-01

    The air velocity in the animal occupied zone (AOZ) of a pig facility influences the thermal comfort of pigs and is affected by the ventilation system in the building. Little is known about the relationship between the air velocity in the AOZ and the ventilation system design. This article describes

  10. Constant-temperature hot-wire anemometer practice in supersonic flows. I - The normal wire

    Science.gov (United States)

    Smits, A. J.; Hayakawa, K.; Muck, K. C.

    1983-01-01

    The performance of a constant-temperature normal hot-wire in a supersonic flow is critically examined. It is shown that this instrument is inherently unsuitable for measuring turbulent temperature correlations because of the highly nonlinear response to temperature fluctuations, particularly at low overheat ratios. The instrument is therefore limited to measurements of mean and fluctuating mass-flow rates. Suitable calibration procedures, as well as the limits on spatial and temporal resolution are discussed, and corrections for mean stagnation temperature changes are suggested.

  11. Note: Improving long-term stability of hot-wire anemometer sensors by means of annealing

    Science.gov (United States)

    Lundström, H.

    2015-08-01

    Annealing procedures for hot-wire sensors of platinum and platinum-plated tungsten have been investigated experimentally. It was discovered that the two investigated sensor metals behave quite differently during the annealing process, but for both types annealing may improve long-term stability considerably. Measured drift of sensors both without and with prior annealing is presented. Suggestions for suitable annealing temperatures and times are given.

  12. The effects of feedback amplifier characteristics on constant temperature hot-wire anemometer systems

    Science.gov (United States)

    Watmuff, J. H.

    1989-01-01

    The 3rd-order analysis of Perry and Morrison (1971) was extended to 7th-order by Watmuff (1987) by including both the bridge-capacitance and the frequency-response characteristics of the feedback amplifier. In this paper, the bridge capacitance has been excluded from the analysis. The influence of the gain K, roll-off frequency f(A), and offset voltage E(qi) of the feedback amplifier are examined in more detail together with their interactions with the bridge inductance.

  13. Constant-temperature hot-wire anemometer practice in supersonic flows. II - The inclined wire

    Science.gov (United States)

    Smits, A. J.; Muck, K. C.

    1983-01-01

    The performance of a constant-temperature inclined hot-wire in a supersonic flow is critically examined. It is shown that calibration techniques applicable to subsonic flow, such as the cosine cooling law cannot be used when the flow is supersonic. Calibration and measurement procedures appropriate to supersonic flow are suggested, together with the possible limits on their validity. Experimental results for different wires indicate that the sensitivities do not seem to depend on flow direction according to any simple correlation. When the sensitivity exhibits a strong dependence on flow direction, the wire should be discarded to avoid errors due to nonlinear effects.

  14. High Reynolds Number Effects on Multi-Hole Probes and Hot Wire Anemometers

    Science.gov (United States)

    Ramachandran, N.; Smith, A.; Gerry, G.; Kauffman, W.

    1995-01-01

    The paper reports on the results from an experimental investigation of the response of multi-hole and hot wire probes at high flow Reynolds numbers (Re approx. 10(exp 6)). The limited results available in literature for 5-hole probes are restricted to Re approx. 10(exp 4). The experiment aims to investigate the probe response (in terms of dimensionless pressure ratios, characterizing pitch, and yaw angles and the total and static pressures) at high Re values and to gauge their effect on the calculated velocity vector. Hot wire calibrations were also undertaken with a parametric variation of the flow pressure, velocity and temperature. Different correction and calibration schemes are sought to be tested against the acquired data set. The data is in the analysis stage at the present time. The test provided good benchmark quality data that can be used to test future calibration and testing methods.

  15. Potential errors in using one anemometer to characterize the wind power over an entire rotor disk

    Science.gov (United States)

    Simon, R. L.

    1982-01-01

    Wind data collected at four levels on a 90-m tower in a prospective wind farm area are used to evaluate how well the 10-m wind speed data with and without intermittent vertical profile measurements compare with the 90-m tower data. If a standard, or even predictable, wind speed profile existed, there would be no need for a large, expensive tower. This cost differential becomes even more significant if several towers are needed to study a prospective wind farm.

  16. Fibre-linked miniature laser transit anemometer for complex flow fields

    Science.gov (United States)

    Hamid, Sohail

    Laser anemometry has been shown to be a very successful optical measurement device. The non-intrusive nature of this technique made it possible to map the flow between the blade rows of a rotating machine which was previously impracticable. The initial designs of the laser anemometry systems have undergone much development and practical problems during the use of these systems still provide room for further development. Some of these problems were identified and solved by designing a miniaturized laser transit system. Miniaturization of the system was achieved by separating the optical head from the bulky and sensitive laser source and detectors. Keeping in view the measurement volume geometry of conventional systems, the optical parameters for the new system were selected. Emphasis was given to the use of optical components which were commercially available in the market. Regarding the arrangement of the optical components inside the system, different models were suggested. A compromise between the optical quality has to be made for practical limitations of cost and ease of operation. The operation of the probe was confirmed by measuring the flow in a simple duct and the blade rows of a rotating axial fan. The comparison of these results with those obtained using a commercial system show that the new probe is working with high accuracy. During near wall applications, some problems were revealed and the probe's performance was not found up to that standard as was expected. Suggestions were made which may improve the systems performance.

  17. Development of a "Digital Bridge" Thermal Anemometer for Turbulence Measurements Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Thermal anemometry (a.k.a. hot-wire anemometry) has been a key experimental technique in fluid mechanics for many decades. Due to the small physical size and high...

  18. A Study of Annular Diffuser Flow Using A Photon-Correlating Laser Doppler Anemometer.

    Science.gov (United States)

    1983-12-01

    average DC voltage. The sampling rate of the TRS-80 is approximately 50 Hertz. FlwMeter. A £ia nstrument Co square-edgedorfc *plate, a Meriam U-tube...inserted upstream into the test sections. The pressure was indi- cated by a Meriam Instrument Co. water micro-manometer. The am- bient air pressure was

  19. Three-dimensional visualization of velocity profiles in the ascending aorta in dogs, measured with a hot-film anemometer.

    Science.gov (United States)

    Paulsen, P K; Hasenkam, J M

    1983-01-01

    Three-dimensional blood velocity profiles were registered in the ascending aorta of dogs approximately 2 and 5 cm above the aortic valves by means of constant temperature hot-film anemometry. The velocity was measured at 41 predetermined points of measurement evenly distributed over the cross-sectional area. Later data analyses using a three-dimensional plotting system, visualized velocity profiles at 200 time intervals during one mean heart cycle. The overall appearance of the profiles was that of a flat transitional flow with a slight skewness. The highest velocity was found nearer to the posterior and left vessel wall. The skewness started during top systole and persisted to the beginning of diastole. Furthermore, many small velocity fluctuations were seen during top systole, but they might also be caused by secondary rotational flow phenomena. This new three-dimensional and dynamic method for visualizing velocity profiles seems to offer advantages, as it demonstrates the total velocity profile all over the cross-sectional area.

  20. Some influences of approximate values for velocity, density and total temperature sensitivities on hot wire anemometer results

    Science.gov (United States)

    Stainback, P. C.

    1986-01-01

    There is a renewed interest in hot wire anemometry at transonic speeds. Recent results were published which indicate that at transonic speeds a heated wire is sensitive only to mass flow and total temperature, results similar to those obtained for supersonic flows. Other results were obtained to show that the sensitivity is a function of velocity, density, and total temperature, results in agreement with many of those obtained in the 1950s. An analysis of anemometry results was made to evaluate possible errors when various assumptions were made concerning the sensitivity of a heated wire to fluid flow variables.

  1. Multi-mode fibre laser Doppler anemometer (LDA) with high spatial resolution for the investigation of boundary layers

    Energy Technology Data Exchange (ETDEWEB)

    Buettner, L.; Czarske, J. [Group Laser Metrology, Laser Zentrum Hannover e.V., Hollerithallee 8, 30419, Hannover (Germany)

    2004-01-01

    A novel LDA system using laser diode arrays and multi-mode fibers in the transmitting optics is presented. The use of high numerical aperture multi-mode step-index fibres results in measurement volumes with, for example, 80 {mu}m length and minimal speckle effects. Because of the high spatial resolution and low relative fringe spacing variation of {delta}d/d{approx}5 x 10{sup -4} the multi-mode fibre LDA is predestined for investigating turbulent flows. Boundary layer measurements carried out show excellent agreement with theoretical velocity profiles. (orig.)

  2. 浅谈EL型电接风向风速仪%Shallowly Discussion the EL Cup of Contact Anemometer

    Institute of Scientific and Technical Information of China (English)

    张放; 冯晋民; 白金凤

    2005-01-01

    随着自动气象站的建设,EL型电接风向风速仪将逐步被新型的自动气象站仪器所代替,EL型电接风向风速仪将作为备份仪器而被保留。侯马市气象局作为国家基准气候站,EL型电接风向风速仪的观测仍作为正式观测项目与自动气象站仪器同步运行。

  3. Guidelines for Evaluating the Thermal Environment of Enclosed Spaces

    Science.gov (United States)

    2009-09-01

    with a variety of instruments. For example, air movement can be measured as mechanical force by cup and propeller anemometers ; electronically, as...Young 3001) Combined unit with cup anemometer and wind vane Air velocity Extech Model 407123 Hot Wire Thermo- Anemometer Hot wire anemometer ...overcome the inertia or stall speed of the familiar cup anemometers . Space limitations and the stall speed of mechanical anemometers usually make

  4. Fixing common breakdowns of cup-contact anemometer and its utilization maintain%电接风的常见故障排除及使用维护

    Institute of Scientific and Technical Information of China (English)

    苏志强; 兰朝生; 白桦

    2002-01-01

    @@ 在我国现有的地面观测常规仪器中电接式风向风速计是测量风向和风速的最基本计量工具.它能够解决地面观测中的2分钟平均风速和10分钟平均风速的观测问题.

  5. Blocking Correction of Anemometer Test in the Wind Tunnel%风速仪在风洞检定中的阻塞修正

    Institute of Scientific and Technical Information of China (English)

    李国森; 敖振浪

    2006-01-01

    文章讨论风速表在风洞中检定(测试)时,其阻塞效应引起的计量误差.根据国家计量量值传递规定,将二元风洞里正圆柱的固体阻塞修正方法扩展为风速传感器阻塞系数的计算方法,建立数学计算模式.

  6. 达因风速仪首次在风洞中比较检定%First Contrast Re-restingof Dines Anemometer in the Wind Tunnel

    Institute of Scientific and Technical Information of China (English)

    陈钦弟; 朱晓燕

    1992-01-01

    @@ 30年代英国制造的达因风速仪在上海龙华气象站使用至今已有40多年.它具有构造原理简单、测量范围广、使用方便及一目了然等优点,是其它风速仪器所不能比拟的.

  7. A new transducer for respiratory monitoring. A description of a hot-wire anemometer and a test procedure for general use.

    Science.gov (United States)

    Kann, T; Hald, A; Jørgensen, F E

    1979-08-01

    A respiratory transducer based on the constant temperature anemometry principle has been developed for respiratory monitoring, and as a tool for bedside evaluation of pulmonary function. The transducer is characterized by a dynamic range from 0-2.5 1/s and an upper limiting frequency of 50 Hz. It is designed with a view to a low pressure drop of 2.5 mbar/1/s and a minimum dead space of 5 ml. The transducer has been tested using a generally applicable procedure which includes both static and dynamic test set-ups. The influence of variation in gas composition, temperature and pressure, together with variations in tidal volume and respiration rate, have been investigated. The results show that the transducer registers the immediate value of gas flow-rate with a mean error less than 5-10% in all situations which are predictable in clinical use. The mean error can be reduced to less than 5% when systematic errors are eliminated.

  8. Flush mounted hot film anemometer measurement of wall shear stress distal to a tri-leaflet valve for Newtonian and non-Newtonian blood analog fluids.

    Science.gov (United States)

    Nandy, S; Tarbell, J M

    1987-01-01

    Wall shear stress has been measured by flush-mounted hot film anemometry distal to an Ionescu-Shiley tri-leaflet valve under pulsatile flow conditions. Both Newtonian (aqueous glycerol) and non-Newtonian (aqueous polyacrylamide) blood analog fluids were investigated. Significant differences in the axial distribution of wall shear stress between the two fluids are apparent in flows having nearly identical Reynolds numbers. The Newtonian fluid exhibits a (peak) wall shear rate which is maximized near the valve seat (30 mm) and then decays to a fully developed flow value (by 106 mm). In contrast, the shear rate of the non-Newtonian fluid at 30 mm is less than half that of the Newtonian fluid and at 106 mm is more than twice that of the Newtonian fluid. It is suggested that non-Newtonian rheology influences valve flow patterns either through alterations in valve opening associated with low shear separation zones behind valve leaflets, or because of variations in the rate of jet spreading. More detailed studies are required to clarify the mechanisms. The Newtonian wall shear stresses for this valve are low. The highest value observed anywhere in the aortic chamber was 2.85 N/m2 at a peak Reynolds number of 3694.

  9. 热线热膜风速计的特点及其应用%Features and application of hot wire film anemometer

    Institute of Scientific and Technical Information of China (English)

    谢东; 刘泽华; 李向阳

    2002-01-01

    @@ 室内气流流动状况,是供暖通风及空调工程专业人员研究的一个重要课题,随着计算机技术和计算流体力学(CFD)的飞速发展,气体流动研究取得了重大的突破.

  10. Fault Diagnosis of the Anemometer in the Wind Turbine Set%风电机组风速仪故障诊断

    Institute of Scientific and Technical Information of China (English)

    黄永民; 禹华军

    2016-01-01

    首先利用风电场的监控数据和粒子群优化算法建立风电机组的基准模型,然后通过基准模型推测风速,并将其与风速仪实际测得的风速进行对比,最后根据残差分析确定风速仪的运行状态,诊断风速仪的故障.

  11. Anemometer Tower Establishment at Guangxi Wind Electric Field%广西风电场测风塔设立综述

    Institute of Scientific and Technical Information of China (English)

    孔建荣

    2006-01-01

    通过广西风电场测风塔的设立过程,从测风塔设立技术规定、测风塔架结构型式、测量仪器选择、测量参数说明、以及测风塔日常管理等方面简述了测风塔设立的主要技术要点,为风电场其他测风塔设立提供参考和借鉴.

  12. Acoustic and Laser Doppler Anemometer Results for Confluent and 12-Lobed E(exp 3) Mixer Exhaust Systems for Subsonic Jet Noise Reduction

    Science.gov (United States)

    Salikuddin, M.; Babbit, R. R.; Shin, H.; Wisler, S.; Janardan, B. A.; Majjigi, R. K.; Bridges, James (Technical Monitor)

    2002-01-01

    The research described in this report has been funded by NASA Glenn Research Center as part of the Advanced Subsonic Technologies (AST) initiative. The program operates under the Large Engine Technologies (LET) as Task Order #3 1. Task Order 31 is a three year research program divided into three subtasks. Subtask A develops the experimental acoustic and aerodynamic subsonic mixed flow exhaust system databases. Subtask B seeks to develop and assess CFD-based aero-acoustic methods for subsonic mixed flow exhaust systems. Subtask B relies on the data obtained from Subtask A to direct and calibrate the aero-acoustic methods development. Subtask C then seeks to utilize both the aero-acoustic data bases developed in Subtask A and the analytical methods developed in Subtask B to define improved subsonic mixed-flow exhaust systems. The mixed flow systems defined in Subtask C will be experimentally demonstrated for improved noise reduction in a scale model aero-acoustic test conducted similarly to the test performed in Subtask A. The overall object of this Task Order is to develop and demonstrate the technology to define a -3EPNdB exhaust system relative to 1992 exhaust system technology.

  13. Acoustic and Laser Doppler Anemometer Results for Confluent, 22-Lobed, and Unique-Lobed Mixer Exhaust Systems for Subsonic Jet Noise Reduction

    Science.gov (United States)

    Salikuddin, M.; Martens, S.; Shin, H.; Majjigi, R. K.; Krejsa, Gene (Technical Monitor)

    2002-01-01

    The objective of this task was to develop a design methodology and noise reduction concepts for high bypass exhaust systems which could be applied to both existing production and new advanced engine designs. Special emphasis was given to engine cycles with bypass ratios in the range of 4:1 to 7:1, where jet mixing noise was a primary noise source at full power takeoff conditions. The goal of this effort was to develop the design methodology for mixed-flow exhaust systems and other novel noise reduction concepts that would yield 3 EPNdB noise reduction relative to 1992 baseline technology. Two multi-lobed mixers, a 22-lobed axisymmetric and a 21-lobed with a unique lobe, were designed. These mixers along with a confluent mixer were tested with several fan nozzles of different lengths with and without acoustic treatment in GEAE's Cell 41 under the current subtask (Subtask C). In addition to the acoustic and LDA tests for the model mixer exhaust systems, a semi-empirical noise prediction method for mixer exhaust system is developed. Effort was also made to implement flowfield data for noise prediction by utilizing MGB code. In general, this study established an aero and acoustic diagnostic database to calibrate and refine current aero and acoustic prediction tools.

  14. Design of a Hot Wire Anemometer with Constant Temperature Feedback%闭环恒温式热线风速传感器的设计

    Institute of Scientific and Technical Information of China (English)

    常严

    2008-01-01

    基于热工学推导了热线风速传感器的数学模型,设计了恒温反馈下的风速测量电路,讨论了非线性模型的分析方法,在此基础上,分析了影响测量精度的一些因素,并给出改进措施.

  15. Flow Velocity and Angularity Measurements in the FDL Transonic Gasdynamic Facility and Self-Adaptive Wall Wind Tunnels with a Laser Transit Anemometer

    Science.gov (United States)

    1981-08-01

    270.83 fRT 18F579T FýF AH 1RTEB/S 2 UNO215 2D)6F 13DT ETA 0•,5 Figura 24. Example of an Angle Search in the SAW Tunnel: Data Versus Angle with 5 Second...provided later in other publica - 0.0 1.00 2.00 tions. In this section we will briefly review the supersonic measurements made with the prototype sys

  16. Comparison research on the anemometer system of wind power generation%用于风力发电的测风系统对比研究

    Institute of Scientific and Technical Information of China (English)

    王宇峰; 裴科伟; 杨嘉鑫; 徐晓敏

    2012-01-01

    介绍了机械式测风传感器与超声波测风传感器的工作原理,比较了它们的特点,及对风力发电的影响。分别对装有2类测风传感器的风力发电机组进行了运行分析,得出2类测风传感器对应的机组功率曲线增长率。试验结果表明:超声波测风传感器进行风速、风向测量更有利于提高风力发电机组的利用率与稳定性。%Introduces the work principle of mechanical wind speed sensor and ultrasonic wind speed sensor, compares their characteristic and the influence of them on the wind power generation, analyzes the operation status of wind power generation units to install two kinds of wind speed sensor, draws the 'power increase rate curve of the wind power generation units' with two kinds of wind speed sensor. The test result shows that using ultrasonic wind speed sensor make the wind speed and direc- tion measurement more beneficial to improve the availability and stability of the wind power genera- tion units.

  17. 三杯式风速计线性特性的实验研究%Static characteristics analysis and experimental study on the three cup anemometer

    Institute of Scientific and Technical Information of China (English)

    姜继海; 周志华; 李岩峰

    2008-01-01

    在稳定空气流的作用下,风速计转速和风速呈一定的线性关系(即风速计的静态特性).通过风洞实验,总结出风杯回转半径和风杯切口面积如何影响风速计的静态特性,为今后设计其它类型的风速计提供理论指导.

  18. Quick and correct error point estimation of cup - contact anemometer%快速准确判断电接风故障点

    Institute of Scientific and Technical Information of China (English)

    白桂巨; 高清兰

    2001-01-01

    @@ 电接风担负着昼夜监测、记录风向风速的任务.由于该仪器插头多,触点多,且其感应器,电缆常年露天工作,风吹雨淋日晒,使用环境条件差,因此故障率较高.要及时地对其进行检修,快速而准确地判断其故障点是前提,这对气象台站有关人员对电接风维护,维修水平的提高有一定的现实意义.

  19. 风杯风速仪过高效应的订正研究%REDUCTION FOR THE OVERSPEED OF CUP ANEMOMETER

    Institute of Scientific and Technical Information of China (English)

    张宏昇; 陈家宜; 朴淳雄

    1999-01-01

    该文基于对风杯风速仪动力方程的数值计算和风杯风速仪与超声风速仪平行对比的观测结果,发现专用于近地面层精细风廓线测量的轻型低阈值风杯风速仪测风的过高效应引起的u-error约为1%,因风速平均方法不同(标量平均和矢量平均)引起的DP-error是风杯风速仪测风过高的主要原因,在小风情况下更为明显.DP-error经修正后可获得合理的风速值.

  20. 电接风电缆线故障的一种解决方法%One Solution Method of Cup-contact Anemometer Cable Breakdown

    Institute of Scientific and Technical Information of China (English)

    常俊明

    2002-01-01

    @@ 现用的地面常规仪器中,电接风向风速计是故障率较高的一种,在各种介绍检修电接风仪器故障的材料中,只介绍了电路部分故障的检修方法,和机械部分的调整方法,似乎电缆故障只有更换.在实际工作中我曾遇到2次风电缆故障,并成功排除,现将我对电缆故障的解决方法写出来,供同行参考.

  1. Terrain Analysis Procedural Guide for Climate,

    Science.gov (United States)

    1980-09-01

    frozen lands which do not tube anemometer , bridled- cup anemometer , support forest vegetation and include the contact anemometer , cooling-power ane...air or other medium sur- rounding an object. (NOO) 125 ANEMOMETER , n. - The general name for ARCTIC REGIONS - That portion of the instruments designed...Fahrenheit. meteorology include the rotation anemnom- These areas generally correspond with eter, pressure-plate anemometer , pressure- those seasonally

  2. Wind and Wind Stress Measurements in HiRes

    Science.gov (United States)

    2009-01-01

    Sonic anemometers for three-dimensional mean and turbulent winds 2. Cup and vane anemometers for mean winds 3. Candidate propeller-vane anemometer to...2 – Paroscientific Barameter, Campbell Sonic Anemometer ; Level 3- 2x Met One Cup , Met One Vane, RM Young Propeller; Level 4 – 2x Met One Cup ; Level...5 – 2x Paroscientific Barometer; Level 6 – Campbell Sonic Anemometer , Modified Krypton Hygrometer, Met One Cup , Met One Vane; Level 7 – 2x RM Young

  3. Wind Tunnel Model and Test to Evaluate the Effectiveness of a Passive Gust Alleviation Device for a Flying Wing Aircraft

    Science.gov (United States)

    2016-10-04

    Jørgensen, F. E. (2002), How to measure turbulence with hot-wire anemometers , Dantec Dynamics, Skovlunde, Denmark. [108] Cao, X., Liu, J., Jiang...measurement There are 3 methods normally used in flow field measurement as following. Solution 1: Hot-wire anemometer system The hot-wire anemometer ...processing. A typical hot-wire probe is shown in Figure D-11 which was the core component for this measurement [107]. Figure D-10 Hot-wire anemometer

  4. Laboratory Study of Wind Effect on Runup over Fringing Reefs. Report 1. Data Report

    Science.gov (United States)

    2007-07-01

    Cup -style anemometer ............................................................................................................. 10 Figure 10...the wind speed in the flume. A cup -style anemometer (Figure 9) was installed near the air intake, and a hot-wire anemometer was installed over the...reef flat. The cup anemometer was an Oregon Scientific Electronic Weather Station Model WM918 with an adver- tised accuracy of 0.18 m/sec or 0.4 mph

  5. Meteorological and Wave Measurements from a Stable Research Platform at Sea

    Science.gov (United States)

    2010-09-30

    array were the instruments measuring airflow velocity (sonic anemometers , cups , vanes), pressure sensors, and the units for GPS tracking and inertial...Height/Location 12 Sonic Anemometers Wind velocity, 10 on the mast, 2 on the boom Air temperature 10 RMY Prop. Anemometers Wind speed & direction

  6. Izmerenie vektora skorosti lazernym dopplerovskim anemometrom (LDA s volokonno-opticheskimi traktami[Measurement of the velocity vector of the laser Doppler anemometer (LDA with fiber-optic tracts

    Directory of Open Access Journals (Sweden)

    S. N. Khotyaintsev

    1982-12-01

    Full Text Available The problems encountered in the development of laser Doppler velocity vector meter optical fiber paths. The scheme of the meter, including three-dimensional velocity meter made by differential circuit. Describes the experimental setup and the results of the experiment by measuring the two projections of the velocity vector.

  7. 煤矿用机械叶片式风速表测量准确度的影响因素%Influencing factor of the accuracy of mine mechanic blade type anemometer

    Institute of Scientific and Technical Information of China (English)

    2016-01-01

    由于煤矿井下的环境较为复杂,煤矿用机械叶片式风速表的测量准确度会降低.针对这一问题,探讨并分析了影响风速表准确度的因素,提出了应对措施,提高了风速表的校正质量.

  8. Three-dimensional visualization of axial velocity profiles downstream of six different mechanical aortic valve prostheses, measured with a hot-film anemometer in a steady state flow model.

    Science.gov (United States)

    Hasenkam, J M; Westphal, D; Reul, H; Gormsen, J; Giersiepen, M; Stodkilde-Jorgensen, H; Paulsen, P K

    1987-01-01

    Hot-film anemometry was used for in vitro steady-state measurements downstream of six mechanical aortic valve prostheses at flow rates 10, 20 and 30 l.min-1. Three-dimensional visualizations of velocity profiles at two downstream levels were made with the valves rotated 0 and 60 degrees in relation to the sinuses of valsalvae. The velocity fields downstream of the disc valves were generally skew with increasing velocity gradients and laminar shear stresses with increasing flow rates. Furthermore, increased skewness of the velocity profiles was noticed when the major orifices of the disc valves were towards the commissure than when approaching a sinus of valsalvae. The velocity profiles downstream of the ball valve were generally flat but with considerably more disturbed flow, consistent with the findings in turbulent flow.

  9. The dynamic response of a hot-wire anemometer: IV. Sine-wave voltage perturbation testing for near-wall hot-wire/film probes and the presence of low-high frequency response characteristics

    Science.gov (United States)

    Teo, C. J.; Khoo, B. C.; Teo, C. J.; Chew, Y. T.

    2001-01-01

    Experiments were performed using the electronic sine-wave voltage-perturbation test to systematically study the frequency responses of near-wall hot-wire probes subjected in turn to varying magnitudes of convective velocity and different effects of wall influence. In addition, quartz-substrate hot-film gauges with various thicknesses of quartz coating were also investigated. Results of the high cut-off frequency obtained using the sine-wave test (fsine) were found to be in fair agreement with those obtained using the square-wave test (fS) both for hot-wire and for hot-film sensors. The sine-wave test response curve exhibited a distinct bulging effect for the hot-film gauges. For the hot-wire sensors, a much weaker bulging effect was also observed. In contrast to fS and fsine, the low frequency response characteristic corresponding to the location of the bulging effect (fbulge) compared much more favourably with the dynamic frequency response (fD) obtained by Khoo et al and Chew et al using a known near-wall fluctuating flow field. Freymuth's theory for non-cylindrical hot-film sensors incorporating the Bellhouse-Schultz model was applied to predict the responses of the hot-film wall gauges when they were subjected to electronic sine-wave testing and dynamic perturbation testing under different parametric conditions. Although it is one-dimensional in nature, the model is capable of predicting most of the trends observed in the present study and previous works by Khoo et al (1998a) and Chew et al (1998a).

  10. Impact of assimilating met-tower, turbine nacelle anemometer and other intensified wind farm observation systems on 0 - 12h wind energy prediction using the NCAR WRF-RTFDDA model

    Science.gov (United States)

    Liu, Y.; Cheng, W.; Liu, Y. W.; Wiener, G.; Frehlich, R.; Mahoney, W.; Warner, T.; Himelic, J.; Parks, K.; Early, S.

    2010-09-01

    In collaboration with Xcel Energy and Vasaila Inc., the National Center for Atmospheric Research (NCAR) conducts modeling study to evaluate the existing and the enhanced intensive observation systems for wind power nowcasting and short-range forecasting at a northern Colorado wind farm. The NCAR WRF (Weather Research and Forecasting model) based Real-Time Four-Dimensional Data Assimilation (RTFDDA) and forecasting system, which has been employed to support Xcel Energy operational wind forecast, was used in this study. The observational data include ten met-towers, a 915Hz wind profiler, a sodar and a Windcube Doppler lidar, besides the in-farm met-towers and wind speed and power reports from more than 300 of wind turbines. The WRF-RTFDDA 4-dimensioanl data assimilation algorithm allows to spread and propagate observation information in the WRF model space (x, y, z and time) with weighting functions built according to the observation location and time. The WRF-RTFDDA was set up to run with four nested domains with grid increments of 30, 10, 3.333 and 1.111km respectively. The standard and diverse non-conventional observations are assimilated on coarse grid domains along with the special wind farm observations. In this study, we investigate a) spread of surface observations in PBL according to PBL depth and regimes, b) optimization of horizontal influence radii and steep-terrain adjustment, and c) impact of different observation platforms and data types on 0 - 12 h wind prediction . It is found that PBL mixing and thermodynamic structures are greatly influenced by the PBL parameterization formulation. The range of the data assimilation effect on forecasts relies on weather and PBL regimes. In most cases, assimilation of in-farm and near-farm observations improves up to 12-hour wind power prediction and assimilation of in-farm data can significantly improves 0 - 6 hour forecasts.

  11. Exceptional Case Analysis of breakdown of the EL Cup of Contact Anemometer%EL电接风向风速计风速不跳故障特例分析

    Institute of Scientific and Technical Information of China (English)

    宋林则; 王宗仁; 张红英; 李红梅; 王晓燕

    2005-01-01

    某县站8月10日EL电接风向风速计记录器从8月10日01时开始出现风速不跳故障。初步分析如果记录器、短电缆、指示器、长电缆都正常时,那可能就是感应器的问题了。经调阅修理记录:全套仪器包括长电缆都是前2个月检修好的,怎么会有这个毛病,很可能是感应器12芯插头座处有了水。

  12. 浅析EL型电接风向风速仪风速测量中的误差问题%Shallowly Analysis the Error Problems of the EL Cup of Contact Anemometer in Wind Speed Measurement

    Institute of Scientific and Technical Information of China (English)

    张虎; 胡苍龙; 李晓红

    2011-01-01

    此文按照《电接风向风速仪检定规程》和《风速仪校验器检定方法》通过检定、测试、校验等测量手段,对电接风向风速仪风速测量中的误差来源进行分析.

  13. 基于数值模拟的三杯式风速仪距离常数的研究%Research on Distance Constant of the Three-Cup Anemometer Based on Numerical Simulation

    Institute of Scientific and Technical Information of China (English)

    袁琨; 许京荆; 魏望望; 戚严文; 朱远

    2016-01-01

    通过分析三杯式风速仪的动态响应方程明确了距离常数与动态响应的关系,利用ANSYS软件建立基于计算流体动力学的风速仪三维数值模拟模型,采用滑移网格技术实现风速仪的旋转运动,准确模拟了风速仪的动态响应过程,计算出风速仪的距离常数,并通过不同风速下风速仪动态响应的数值模拟验证了结果的准确性,为三杯式风速仪距离常数的研究提供了新的方法.

  14. Cup Anemometers’ Loss of Performance Due to Ageing Processes, and Its Effect on Annual Energy Production (AEP Estimates

    Directory of Open Access Journals (Sweden)

    Alfredo Sanz

    2012-05-01

    Full Text Available The deviation of calibration coefficients from five cup anemometer models over time was analyzed. The analysis was based on a series of laboratory calibrations between January 2001 and August 2010. The analysis was performed on two different groups of anemometers: (1 anemometers not used for any industrial purpose (that is, just stored; and (2 anemometers used in different industrial applications (mainly in the field—or outside—applications like wind farms. Results indicate a loss of performance of the studied anemometers over time. In the case of the unused anemometers the degradation shows a clear pattern. In the case of the anemometers used in the field, the data analyzed also suggest a loss of performance, yet the degradation does not show a clear trend. A recalibration schedule is proposed based on the observed performances variations.

  15. Digital technique for the simultaneous measurement of velocity and temperature.

    Science.gov (United States)

    Keffer, J F; Budny, R S; Kawall, J G

    1978-09-01

    A computer-oriented, hot-wire anemometer technique for the simultaneous measurement of velocity and temperature in heated turbulent flows is described. This technique involves conversion of analogue anemometer voltage signals into digital forms and processing of these latter on a digital computer, in accordance with the anemometer response equations, to obtain instantaneous temperature and velocity. The technique was tested with a heated plane jet and found to be satisfactory.

  16. Transition to Turbulence in the Separated Shear Layers of Yawed Circular Cylinders

    Science.gov (United States)

    2010-04-15

    where her hot - wire anemometer measurements found their streamwise appearance (after separation) to be inversely proportional to the cylinder Reynolds...Smith (1986) conducted hot - wire anemometer measurements where they reported expo- nents b = 0.87 and b = 0.773, respectively, for the Bloor power- law...measured when using anemometry . Prasad and Wil- liamson (1996) compiled their anemometer measurements along with those of Bloor as well as Wei and

  17. Particulate Matter Emissions for Dust From Unique Military Activities

    Science.gov (United States)

    2007-12-31

    three towers is also instrumented with cup anemometers to measure the vertical wind speed profile and a wind vane to measure wind direction. The...magnitude of the dust emissions, SI-1399 also collected 3-dimensional wind speed data generated by the rotor-wash using a sonic anemometer deployed in...diameters from the position of the sonic anemometer . Four Irwin sensors (Irwin, 1980), which have been previously used to measure surface shear

  18. Validation of the Rotorcraft Flight Simulation Program (C81) Using Operational Loads Survey Flight Test Data.

    Science.gov (United States)

    1980-07-01

    could be improved by the use of one of the sensitive, accurate, cup - anemometer type of airspeed sensors that have recently been developed. 8.1.4...programs of this nature to enhance their use for the validation of simulation programs: - Remove the airspeed sensor from the boom and use a cup - anemometer ...transducers to allow access to the instrumentation. Hot-wire anemometers were then applied to the leading edge at the same five blade stations. 24 The

  19. Study of a Wind Energy Conversion System in New Hampshire.

    Science.gov (United States)

    1981-08-01

    and quality of output signal. Cup anemometers and vanes were selected with the following character- istics: Wind Speed Accuracy + .25 mph Range 0-100...icing conditions. In particular, the anemometer cups were attached to their supporting shafts with relatively weak epoxy bonds. This drawback was...turbine installation. 5.2 METHOD Eight sets of cup anemometers and wind vanes were calibrated at the MIT Wright Brothers Wind Tunnel (Cambridge, Mass

  20. The Low-Level Wind Shear Alert System (LLWSAS)

    Science.gov (United States)

    1980-05-01

    known overshooting problems of cup -type anemometers such as the model F-420, the NWS sensor has far more severe damping characteristics than the LLWSAS...the Low-Level Wind Shear Alert System (LLWSAS) field test and evalua- tion are reported. The system is a computer controlled anemometer mesonetwork...Hardware 17 LLWSAS Software 46 Anemometer Siting Criteria 64 LLWSAS Data Collection and Analysis 88 Airport Sensor Configurations, Special Siting Factors

  1. A Design Study for a Meteorological Instrumentation System for an OMEGA Tower.

    Science.gov (United States)

    1981-07-01

    count, recycling after a count of 256. They are convenient to use with pulse or pulse rate output devices such as cup anemometers or propellors. For...some transducer configurations are con’nidered. 4.4.1 Wind Velocity Transducers which have been considered for this parameter are: Sonic anemometer ...Vortex shedding anemometer /vane Bivane and propellor. While these all have particular advantages it is considered that the best compromise between

  2. Measurements of the Air-Sea Interface from an Instrumented Small Buoy

    Science.gov (United States)

    2011-09-01

    at three levels to characterize the vertical variation of the wind. The 3- cup anemometer sensor is a plug-in HOBO weather station wind sensor. It...this configuration, the anemometers are located at three levels together with the temperature and humidity sensors inside radiation shields 8 at...experiment that would allow them to measure simultaneously at the same location. The anemometers and the HOBO temperature and RH sensors were placed

  3. Factors Affecting Coast Guard SAR Unit Visual Detection Performance.

    Science.gov (United States)

    1981-08-01

    and outer search legs were one-half the track spacing (S) inside the perimeter of the search area. cuP r MINOR AXIS SKETCH 1. PARALLEL SEARCH PATTERN...SRU. Wind speed and direction were recorded using a hand-held anemometer onboard the OSC vessel and an installed anemometer or an estimate onboard the...Surface wind measurements or estimates were made at various heights between the anemometer located at 90 feet and the sea surface (OSC at 10 feet

  4. Experimental Evaluation of the Atmospheric Energy Input to Sea Surface Waves

    Science.gov (United States)

    2011-09-30

    with sonic anemometers , cups , vanes, measuring airflow velocity, sensitive barometers. Instruments for GPS and inertial navigation were positioned...constant, Ω is the Instruments Quantity measured Height/Location 7 Sonic Anemometers Wind velocity, Air temperature On the mast 5 RMY Prop... Anemometers Wind speed & direction At 5 levels on the mast 8 Pressure Instruments Atmospheric pressure On the mast 2 Wave Wires Sea surface elevation At

  5. The Feasibility of Sodar Wind Profile Measurements from an Oceanographic Buoy

    Science.gov (United States)

    2006-09-01

    with cup anemometer measurements (Jorgenson et. al., 2004). The main difficulty in the CW approach is how to determine range. The ZephIR uses a...Doppler LIDAR – Comparison with Cup Anemometers at RISØ. Proc. European Wind Energy Conference, Delft, April 2004, pp. 1–6. Pierce, Allan D. (1981...misalignment of winds and currents. One way to improve the model in the future would be to equip ASIS with an anemometer , a downward-looking ADCP, and a GPS

  6. Replication of Atmospheric Conditions for the Purpose of Testing MAVs. MAV Flight Environment Project

    Science.gov (United States)

    2005-12-23

    atmospheric measurements Wind data are traditionally obtained utilizing propeller, cup , dynes or ultrasonic anemometers that are placed either in...Information was obtained by wind engineers from relatively large anemometers on fixed masts at heights well removed from the ground (in order to...isolation or located on vertical masts with inter- anemometer spacing of several metres. This reflects the interest of the building or road vehicle

  7. Investigation of Atmospheric Laser Optics Test bed (A_LOT) Optical Turbulence Intensity for Free-Space Laser Communications

    Science.gov (United States)

    2006-12-01

    data include mean temperature, wind speed (small three- cup anemometer ), barometric pressure, relative humidity, and rainfall amount. We have also...integrated a single three-axis sonic anemometer (R.M. Young Company1, Model 81000) alongside the rooftop weather station. The sonic sensor provides...and mean and fluctuating temperature data). Basically, a sonic anemometer determines wind speed and wind direction by measuring the change in the

  8. Distributed hot-wire anemometry based on Brillouin optical time-domain analysis.

    Science.gov (United States)

    Wylie, Michael T V; Brown, Anthony W; Colpitts, Bruce G

    2012-07-02

    A distributed hot-wire anemometer based on Brillouin optical time-domain analysis is presented. The anemometer is created by passing a current through a stainless steel tube fibre bundle and monitoring Brillouin frequency changes in the presence of airflow. A wind tunnel is used to provide laminar airflow while the device response is calibrated against theoretical models. The sensitivity equation for this anemometer is derived and discussed. Airspeeds from 0 m/s to 10 m/s are examined, and the results show that a Brillouin scattering based distributed hot-wire anemometer is feasible.

  9. The Wind Speed Spectrum in an Industrial Environment or Does the Spectral Gap Exist?

    Science.gov (United States)

    1979-10-01

    North. 2.2 The Anemometers The anemometers used were a three cup variety. The cups were made by Casella and Co Limited and their light weight...spectrum over the entire frequency band. 2. EXPERIMENTAL PROCEDURE 2.1 Site of the Experiment The anemometers used in the experiment were situated at the...metres. One of the anemometers (hereafter called anemo- meter A) was sited on the end of a building at a height of 14 metres above the ground and 2

  10. Chemical, Biological, and Radiological (CBR) Contamination Survivability, Large Item Interiors

    Science.gov (United States)

    2016-08-03

    per second (m/s)). Anemometer or similar measuring instrument with digital recording capability. ±0.1 m/s. Photographs. Still color camera...capabilities (both lethal and nonlethal) over time. TOP 08-2-509A 3 August 2016 B-1 APPENDIX B. TEST EQUIPMENT. Thermocouple. Hygrometer. Anemometer

  11. Developing a Data Set and Processing Methodology for Fluid/Structure Interaction Code Validation

    Science.gov (United States)

    2007-06-01

    hollow support shaft. 1.2.4.3 Vibrometer System A PolyTec laser vibrometer was used to supplement the other instrumentation for all flexible test...Anemometer (HWA) Empty Tunnel Changed CADDMAS inputs to eliminate Polytec positions for anemometer inputs...Def." -moved Polytec velocity--channel 17 (airfoil AOA accel) -moved Polytec displacement--channel 18 (airfoil flap accel

  12. Validation of the SODAR properties, June 2006

    DEFF Research Database (Denmark)

    Hansen, Kurt Schaldemose

    -anemometers, 1 wind vane and one 3-D ultrasonic anemometer sampled at 10 Hz using a low- power industrial computer. Statistics were transmitted every 10 minutes using SMS telegrams. The SODAR was a METEK PCS-2000.24 low power version. All equipment was powered by a commercial off-grid power system designed...

  13. Wind measurements for wind energy applications. A review

    DEFF Research Database (Denmark)

    Mortensen, N.G.

    1994-01-01

    A review is given of the error sources and uncertainties in cup and sonic anemometry. In both cases the effects of the tower, boom and other mounting arrangements, as well as the siting of the anemometer, should be considered carefully. Cup anemometer measurements are inherently biased due to the...

  14. Stratus Ocean Reference Station (20 deg S, 85 deg W) Mooring Recovery and Deployment Cruise, R/V Ronald H. Brown Cruise 06-07, October 9-October 27, 2006

    Science.gov (United States)

    2007-02-01

    corrections mounted on the jackstaff. The jackstaff sensors are: GILL Sonic anemometer, Fast Ozone Sensor’s inlet, LiCor LI-7500 fast C0 2/hygrometer...averages. A central data acquisition computer logs all sources of data via RS-232 digital transmission: I. Sonic Anemometer 2. Licor C02/H20 3. Slow

  15. Design and Study of a Low-Cost Laboratory Model Digital Wind Power Meter

    Science.gov (United States)

    Radhakrishnan, Rugmini; Karthika, S.

    2010-01-01

    A vane-type low-cost laboratory model anemometer cum power meter is designed and constructed for measuring low wind energy created from accelerating fluids. The constructed anemometer is a device which records the electrical power obtained by the conversion of wind power using a wind sensor coupled to a DC motor. It is designed for its…

  16. Comparison of USARIEM Heat Strain Decision Aid to Mobile Decision Aid and Standard Army Guidelines for Warm Weather Training

    Science.gov (United States)

    2008-06-01

    anemometer 1.5 m, 2 m above ground R.M. Young 03001-5 three cup anemometer 2 m above ground RH Vaisala HMP36 Vaisala HMP35 radiation shield mounted at...LI200X pyranometer mounted 1.5 m above ground and unshaded by weather instruments or surrounding vegetation WS R.M. Young 03001-5 three cup

  17. Analysis of Aerosols and Fallout from High-Explosive Dust Clouds. Volume 2

    Science.gov (United States)

    1977-03-01

    three cup anemometer driving a DC generator was used to measure wind speed. The perform- ance of this sensor is equivalent to an MRI Model 1074-6...Performance The anemometer and wind vane operated properly. It was ! planned to operate the recorder at 0. 75 inches per minute during the final hours before

  18. Thermal Stress Inside the XM-1 Tank Ddring Operations in an NBC Environment and Its Potential Alleviation by Auxiliary Cooling.

    Science.gov (United States)

    1981-05-20

    cup anemometer while a hot wire anemometer was used to measure interior air motion. Physiological measurements. The physiological responses of each...speed transmitter with cups 1 H.P. 5300 B counter (for wind speed) 2 boxes assorted Hi-tape (for skin couples) 10 rolls ECG paper 6 rolls H.P. printer

  19. BOBMEX: The Bay of Bengal Monsoon Experiment

    Digital Repository Service at National Institute of Oceanography (India)

    Bhat, G.S.; Gadgil, S.; Kumar, P.V.H.; Kalsi, S.R.; Madhusoodanan, P.; Murty, V.S.N.; Rao, C.V.K.P.; RameshBabu, V.; Rao, L.V.G.; Rao, R.R.; Ravichandran, M.; Reddy, K.G.; Rao, P.Sanjeeva; Sengupta, D.; Sikka, D.R.; Swain, J.; Vinayachandran, P.N.

    ) observation po- sition on the Research Vessel SK are shown in Fig. 5b. Hand-held cup Deck (~14 m) Ogawaseiki, Japan — b 3 h SK anemometer (metkit), sonic anemometer, Boom (~11.5 m) Metek, Germany 0.1 m s −1 1 min Continuous, 0.1 Hz Wind Gill anemometer Boom... (~11.5 m) R. M. Young, U.S.A. 0.2 m s −1 1 min Continuous, 0.1 Hz SD Hand-held Deck (~10 m) — — b 3 h cup anemometer DS3 Cup anemometer Tower (3 m) Lambrecht 1.5% FS 10 min c 3 h TABLE 1. Major meteorological sensors/instruments operated during BOBMEX...

  20. Flow tilt angles near forest edges - Part 1: Sonic anemometry

    DEFF Research Database (Denmark)

    Dellwik, Ebba; Mann, Jakob; Larsen, Klaus Steenberg

    2010-01-01

    -sets. These features of the investigated sonic anemometers make them unsuitable for measuring vertical velocities over highly turbulent forested terrain. By comparing the sonic anemometer results to that of a conically scanning Doppler lidar (Dellwik et al., 2010b), sonic anemometer accuracy for measuring mean flow...... distortion and vertical alignment, it was only possible to a limited extent to relate sonic anemometer flow tilt angles to upwind forest edges, but the results by the lidar indicated that an internal boundary layer affect flow tilt angles at 21m above the forest. This is in accordance with earlier studies......An analysis of flow tilt angles from a fetch-limited beech forest site with clearings is presented in the context of vertical advection of carbon dioxide. Flow angles and vertical velocities from two sonic anemometers by different manufacturers were analyzed. Instead of using rotations, where zero...

  1. On wind turbine power performance measurements at inclined airflow

    Science.gov (United States)

    Pedersen, T. F.

    2004-07-01

    The average airflow inclination in complex terrain may be substantial. The airflow inclination affects wind turbine performance and also affects the cup anemometer being used in power performance measurements. In this article the overall dependence of the power curve on inclined airflow is analysed for its influence on both the wind turbine and the cup anemometer. The wind turbine performance analysis is based on results of measurements and theoretical calculations with the aeroelastic code HAWC coupled to a 3D actuator disc model for varying yaw angle. The cup anemometer analysis at inclined flow is based on an averaging of measured angular characteristics in a wind tunnel with the distribution of airflow inclination angles over time. The relative difference in annual energy production in terrain with inclined airflow compared with flat terrain is simulated for cup anemometers with theoretical optimal angular characteristics for two different definitions of wind speed, as well as for five commercial cup anemometers with measured angular characteristics. Copyright

  2. Analysis and design of the experiment box for the starting wind velocity threshold calibration of cup anemometer%风杯式风速传感器启动风速校准实验箱的分析与设计

    Institute of Scientific and Technical Information of China (English)

    行鸿彦; 于祥; 邹水平; 赵晨

    2015-01-01

    针对风杯式风速传感器启动风速现场实时校准问题,分析了影响风杯式风速传感器启动风速的因素,提出了现场测量启动风速的方法,基于此方法设计了启动风速校准实验箱,为获得最优实验箱结构参数,通过Fluent软件分别研究了不同结构的动力段、整流段以及收缩段对实验箱流场形态的影响,选取合适的结构,确定了实验箱结构在不同风扇转速下的流场形态,结果表明:所设计的实验箱出口段气流速度平稳,方向一致,满足校准需求.

  3. Impact of sea breeze of the sea off Goa, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Neetu, S.; Shetye, S.R.; Chandramohan, P.

    . OBSERVATIONS AND ANALYSIS The wind observations were made using an anemometer located on the terrace of the main building ofthe National Institute of Oceanography, Goa. The height ofthe anemometer was about 50 m above sea level. The recorded data were ten...Goa is oriented along approximately 340°. Hence the sea breeze at the height of about 50 metres above sea level recorded by the anemometer is almost along the coastline. Though this angle might have come under the influence of the shape of the building on which...

  4. Decadal and long-term sea level variability in the tropical Indo-Pacific Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Nidheesh, A.G.; Lengaigne, M.; Vialard, J.; Unnikrishnan, A.S.; Dayan, H.

    the model forcing is based) are subject to spurious variations caused by changes in the observing system, or measurement methods (e.g. the effect of anemometer height discussed in Tokinaga and Xie 2011). To assess the robustness of the model wind forcing... and wind wave-height ship observations archived in the ICOADS database. This Wave and Anemometer-based Sea surface Wind (WASWind; Tokinaga and Xie 2011) dataset is corrected for spurious upward trend due to increases in anemometer height and provides wind...

  5. Full-Scale Spectrum of Boundary-Layer Winds

    DEFF Research Database (Denmark)

    Larsén, Xiaoli Guo; Larsen, Søren Ejling; Lundtang Petersen, Erik

    2016-01-01

    Extensive mean meteorological data and high frequency sonic anemometer data from two sites in Denmark, one coastal onshore and one offshore, have been used to study the full-scale spectrum of boundary-layer winds, over frequencies f from about 1 yr−1 to10 Hz. 10-min cup anemometer data are used...... to estimate the spectrum from about 1 yr−1 to 0.05 min−1; in addition, using 20-Hz sonic anemometer data, an ensemble of 1-day spectra covering the range 1 day−1 to 10 Hz has been calculated. The overlapping region in these two measured spectra is in good agreement. Classical topics regarding the various...

  6. Near Wall Velocity and Vorticity Measurements, In A Very High R(theta) Turbulent Boundary Layer

    Science.gov (United States)

    2006-06-15

    horizontal bar positioned at a height of 1.5 meters, to which an R.M. Young 03 101-X 3- cup anemometer and 03101 electronic wind vane were mounted. The...mount for the wind vane and 3- cup anemometer were positioned at the site on the north side of the access road in anticipation of a prevailing northerly...The three cup anemometer and electronic wind vane were positioned atop the tripod at a sensing height of 1.8 meters; see Fig. 4-11. The electronic

  7. Technologic Papers of the Bureau of Standards. Number 237. Aeronautic Instruments,

    Science.gov (United States)

    2007-11-02

    the motion of the airplane or on the speed of rotation of small cup anemometers ’or air propellers. -The indicati6ns of the pressure type are pro...developed by these instruments also obeys the pv2 law. In instruments of the anemometer type the air speed is determined by the rate of revolution by a cup ...to a third sighting Huntl Aeronautitc In struments. 461 FIG. 13.-Pensuti pressure plate air-speed indicator. FIG. 14.-Morell cup anemometer air-speed

  8. 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

  9. Seasonal variability of physico-chemical characteristics of the Haldia channel of Hooghly estuary, India

    Digital Repository Service at National Institute of Oceanography (India)

    Sadhuram, Y.; Sarma, V.V.; Murty, T.V.R.; Rao, B.P.

    . 2.1.6 Meteorological observations Data on surface meteorological parameters, viz., wind speed, dry bulb and wet bulb temperatures, were collected at di?erent locations, during the observational period. Wind speed was measured by portable anemometer...

  10. 40 CFR 1065.245 - Sample flow meter for batch sampling.

    Science.gov (United States)

    2010-07-01

    ... averaging Pitot tube, or a hot-wire anemometer. Note that your overall system for measuring sample flow must... diluted exhaust and sample-flow measurements and their upstream pressures and temperatures remain...

  11. 40 CFR 1065.230 - Raw exhaust flow meter.

    Science.gov (United States)

    2010-07-01

    ... averaging Pitot tube, a hot-wire anemometer, or other measurement principle. This would generally not... cooling. (2) If cooling causes exhaust temperatures above 202 °C to decrease to below 180 °C, do...

  12. ACCUWIND - Accurate wind speed measurements in wind energy - Summary report

    DEFF Research Database (Denmark)

    Friis Pedersen, Troels; Dahlberg, J.-Å.; Cuerva, A.;

    2006-01-01

    been used by meteorologists for turbulencemeasurements, 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 proceduresfor......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 performancemeasurements for certification...... and CLASSCUP from which the proposed classification method for cup anemometers was developed for the IEC standard. While cup anemometers at present are the standardanemometer being used for average wind speed measurements, sonic anemometers have been developed significantly over the last years, and prices have...

  13. Stable Atmospheric Boundary-Layer Experiment in Spain (SABLES 98): A Report

    Science.gov (United States)

    Cuxart, J.; Yague, C.; Morales, G.; Terradellas, E.; Orbe, J.; Calvo, J.; Fernandez, A.; Soler, M.R.; Infante, C.; Buenestado, P.; Espinalt, A.; Joergensen, H.E.; Rees, J.M.; Vila, J.; Redondo, J.M.; Cantalapiedra, I.R.; Conangla, L.

    This paper describes the Stable AtmosphericBoundary Layer Experiment in Spain (SABLES 98),which took place over the northern Spanish plateaucomprising relatively flat grassland,in September 1998. The main objectives of the campaign were to study the properties of themid-latitude stable boundary layer (SBL).Instrumentation deployed on two meteorologicalmasts (of heights 10 m and 100 m)included five sonic anemometers, 15 thermocouples,five cup anemometers and three propeller anemometers,humidity sensors and radiometers.A Sensitron mini-sodar and a tetheredballoon were also operated continuously. Atriangular array of cup anemometers wasinstalled to allow the detection ofwave events. Two nocturnal periods analysedon 14-15 and 20-21 September are used toillustrate the wide-ranging characteristics of the SBL.

  14. Wind speed assessment at Treculliacks, Constantine, Falmouth, Cornwall

    Energy Technology Data Exchange (ETDEWEB)

    Williams, G.J.; Angell, R.K.; Collis, J.A.; Odgers, M.; Beechey-Newman, H.J.A.; Shaw, G.A.

    1995-05-01

    An anemometer mast was erected at Treculliacks close to the proposed position for Windpower`s next wind turbine. Anemometers were mounted at 15 and 25 m agl. Wind velocity was monitored from June 1991 to February 1992 inclusive and referenced to the long term record at St. Mawgan. The predicted long term mean annual wind speed was compared with the measured results. The net annual wind turbine output is predicted. (UK)

  15. Variable temperature hot wire anemometry applied to the joint analysis of the velocity and temperature fluctuations in a mixing layer

    OpenAIRE

    Ndoye, M.; Delville, J.; Dorignac, E.; Arroyo, G.

    2011-01-01

    International audience; Our study provides a detailed description of the thermal mixing process in an anisothermal mixing layer. Velocity and temperature are simultaneously measured at the same point by using a new hot wire anemometer. This anemometer implements the multiple overheat principle, associated with a non linear Levenberg-Marquardt signal processing. These simultaneous measurements allowed an analysis based on conditional Probability Density Functions (PDFs), joint PDFs and a quadr...

  16. Flow and Heat Transfer Characteristics behind Circular Cylinders with Different Size

    OpenAIRE

    布施, 肇; 鳥居, 修一; 有薗, 美和; フセ, ハジメ; トリイ, シュウイチ; アリゾノ, ミワ; FUSE, Hajime; Torii, Shuichi; ARIZONO, Miwa

    1992-01-01

    An experimental study is conducted on heat transfer from slightly heated circular cylinders with various diameters in cross flow under the same condition of the free-stream turbulence. Emphasis is placed on the influence of the diameter of the cylinder, D, on the heat transfer coefficient at the rear stagnation point. By using a hot-wire anemometer, spectrum analysis of the anemometer signal with a Fourier analyzer is etmployed to investigate the separated shear layer formed behind the circul...

  17. Dual Mode Thin Film Bulk Acoustic Resonators (FBARs) Based on AlN, ZnO and GaN Films with Tilted c-Axis Orientation

    Science.gov (United States)

    2010-01-01

    vol. 40, pp. 473– 481, 2006. [4] C. G. Lomas, Fundamentals of Hot Wire Anemometry . New York: Cambridge University Press, 1986. [5] D. S. Ballantine, Jr...Additionally, the widely used thermal anemometers such as hot - wire anemometer, can measure the flow in a precise location and has extremely high... wires were bonded to the resonator electrodes through sil- ver paste, which provides electrical connection for reso- nator impedance measurement. The

  18. Retrieving wind statistics from average spectrum of continuous-wave lidar

    DEFF Research Database (Denmark)

    Branlard, Emmanuel; Pedersen, Anders Tegtmeier; Mann, Jakob

    2013-01-01

    -order atmospheric turbulence statistics. An atmospheric field campaign and a wind tunnel experiment are carried out to show that the use of an average Doppler spectrum instead of a time series of velocities determined from individual Doppler spectra significantly reduces the differences with the standard deviation...... measured using ordinary anemometers, such as ultra-sonic anemometers or hotwires. The proposed method essentially removes the spatial averaging effect intrinsic to the cw lidar systems....

  19. Thermal flow micro sensors

    OpenAIRE

    Elwenspoek, M.

    1999-01-01

    A review is given on sensors fabricated by silicon micromachining technology using the thermal domain for the measurement of fluid flow. Attention is paid especially to performance and geometry of the sensors. Three basic types of thermal flow sensors are discussed: anemometers, calorimetric flow sensors and time of flight flow sensors. Anemometers may comprise several heaters and temperature sensors and from a geometric point of view are similar sometimes for calorimetric flow sensors. We fi...

  20. Characterization of the Time-Dependent Fluid-Structure Interaction of Passive Flow Control of Low Reynolds Number Membrane Wings

    Science.gov (United States)

    2013-07-01

    single-point flow velocity and membrane vibration velocity measurements were recorded via a hotwire (HW) anemometer and laser vibrometer (LV...solvent in the primer to evaporate for approximately 30 minutes, the two parts of raw silicone (Dragon Skin Shore 20A) were mixed in a separate cup to... anemometer and laser vibrometer measurements permitted coherence analysis between the two time-resolved data series. Coherence assessment between the two

  1. A Landsat Data Collection Platform at Devil Canyon Site, Upper Susitna Basin, Alaska. Performance and Analysis of Data.

    Science.gov (United States)

    1979-02-01

    provided by a rotary cup anemometer with a RESULTS AND DISCUSSION small reed switch that momentarily closes its contacts for each 0.16 km of wind...ice formation w hich immobilized the Water equivalent data from the snow pillow, anemometer cups . A lso, one cup was found to as measured by the Stevens...recorder during the be twisted on the April site visit. The date the period 7 November 1974-7 April 1975, are shown cup became twisted (sometime

  2. Stratus 10: Tenth Setting of the Stratus Ocean Reference Station. Cruise RB-10-01 January 2 - January 30, 2010 Charleston, South Carolina - Valparaiso, Chile

    Science.gov (United States)

    2010-05-01

    first time during this cruise) in the early morning. Move to Stratus 9 and keep station at 07:00 EST for next 24 hours. Deep CTD (4000m, with cups ...different angles and the vanes of the anemometers are visually oriented towards the reference direction, and blocked. Wind is recorded for 15 minutes at...rotations of the propellers, but this measurement is noisier. A Gill Sonic Wind Sensor was incorporated on the Stratus 9 and 10 buoy. The anemometer

  3. A comparison of a coaxial focused laser Doppler system in atmospheric measurements

    Science.gov (United States)

    Karaki, S.

    1973-01-01

    Measurements of atmospheric velocities and turbulence with the laser Doppler system were obtained, and the results compared with cup anemometer and hot-wire measurements in the same wind field. The laser Doppler velocimeter (LDV) is described along with the test procedures. It was found that mean values determined from the LDV data are within 5% of other anemometer data for long time periods, and the LDV measures higher velocities.

  4. Storm Warnings on Lake Balaton,

    Science.gov (United States)

    1982-04-06

    magnitude of this effect. Consequently, the employees of the Storm Warning Service decided in the course of the summer 1962, to set up a cup -type... anemometer on a passenger ship regularly passing between Si6fok and Balatonfired, and to take wind measurements along this route across the Lake in a...along this route. During the measurements, the reading of the anemometer was taken at intervals and noted together with the time of reading. Since the

  5. Characterization of the Flow Field and Wind Speed Profiles in Microbalance Wind Tunnels for Measurement of Agent Fate

    Science.gov (United States)

    2005-10-01

    wind speeds. Figure 4 shows the internal components of the Model Q600, including the 23mm diameter flow tube. Sample Cup Reference Cup Purge Gas...using a constant temperature hot-film anemometer (IFA-300 system; TSI, Minneapolis, MN). Special care was taken to extend the hotwire probe calibration...were performed from within approximately 0.254mm of the sample pan to near the top of the tube. The hot wire anemometer probes were mounted on a high

  6. Extreme-value time-series analysis of Australian Region A gust wind speeds to examine instrument bias

    Science.gov (United States)

    Cechet, R. P.; Sanabria, L. A.

    2010-08-01

    Australian building codes through the Australia/New Zealand Wind Actions Standard as well as the wind engineering community in general rely to a significant extent on the peak gust wind speed observations collected over more than 70 years by the Australian Bureau of Meteorology (BoM). In the mid-1980's BoM commenced a program to replace the aging pressure tube Dines anemometers with cup anemometers. During the replacement procedure, many localities had more than one type of anemometer operating, recording extreme events. Systematic differences between instrument measurements during this overlap period raised serious concerns about the utility of the peak gust wind speed database. This paper presents the results of a reanalysis of the current BoM peak wind gust database for the non-cyclonic region (Region A) of the Australia/New Zealand Wind Actions Standard. The study utilises extreme value distribution analysis and compares estimates of the 500-year return-period (RP) peak gust wind exceedance level derived from segments of the record measured with the Dines and replacement anemometers. Results indicate that the later period appears to have a significant reduction in extreme events; 17 of 31 sites have a mean 500 year RP exceedance level for the replacement anemometer section of the record below the lower 95% confidence limit for the Dines anemometer part of the record. The 3PM mean wind speed time-series observations have also been examined, and they exhibit a similar trend.

  7. Cup anemometry in wind engineering, struggle for improvement

    Energy Technology Data Exchange (ETDEWEB)

    Albers, A.; Klug, H.; Westermann, D. [DEWI, Wilhelmshaven (Germany)

    2001-02-01

    Large deviations between measurements with cup anemometers of different types in turbulent air flow have recently been identified. The key problem resulting for the wind industry is that wind speed measurements performed with different anemometer types are not directly comparable. Solutions for this problem are believed to be found in a classification of cup anemometers or a correction among different cup anemometer types, while the focus must not necessarily lie on the determination of the true wind speed. The investigated cup anemometers fall roughly into two groups, namely the Risoee P2445b, the Vector A100 and the Metone 010C-1 anemometers tend to measure less wind speed in turbulent flow than the Thies 4.3303.22.X, the Friedrichs 4033.1100X and the Thies Compact anemometers. Measurements with a calibrated ultra sonic anemometer of type Gill Windmaster were closer to the first group at high wind speeds and to the latter group at lower wind speeds. Up to now all simple classification schemes oriented on basic physical properties of the cup anemometers, like the shape of the cups, the shape of the body or the size of the cups, were not successful. Also a classification of the cup anemometers according to their static response to vertically inclined air flow as measured in wind tunnels turned out to be inappropriate. A correction between the different groups of cup anemometers requires the knowledge which meteorological parameters have to be considered for the determination of the correction. From the existing measurements it is clear that such a correction is site specific and must account for the turbulence intensity. However, some cases appeared where at different sites with comparable turbulence intensity different deviations between the same pair of cup anemometers occurred which indicates that other flow parameters than the turbulence intensity also play an important role. (orig.) [German] Im Rahmen von Forschungsaktivitaeten unter Beteiligung des DEWI

  8. Description of the Columbia Basin Wind Energy Study (CBWES)

    Energy Technology Data Exchange (ETDEWEB)

    Berg, Larry K.; Pekour, Mikhail S.; Nelson, Danny A.

    2012-10-01

    The purpose of this Technical Report is to provide background information about the Columbia Basin Wind Energy Study (CBWES). This study, which was supported by the U.S. Department of Energy’s Wind and Water Power Program, was conducted from 16 November 2010 through 21 March 2012 at a field site in northeastern Oregon. The primary goal of the study was to provide profiles of wind speed and wind direction over the depth of the boundary layer in an operating wind farm located in an area of complex terrain. Measurements from propeller and vane anemometers mounted on a 62 m tall tower, Doppler Sodar, and Radar Wind Profiler were combined into a single data product to provide the best estimate of the winds above the site during the first part of CBWES. An additional goal of the study was to provide measurements of Turbulence Kinetic Energy (TKE) near the surface. To address this specific goal, sonic anemometers were mounted at two heights on the 62 m tower on 23 April 2011. Prior to the deployment of the sonic anemometers on the tall tower, a single sonic anemometer was deployed on a short tower 3.1 m tall that was located just to the south of the radar wind profiler. Data from the radar wind profiler, as well as the wind profile data product are available from the Atmospheric Radiation Measurements (ARM) Data Archive (http://www.arm.gov/data/campaigns). Data from the sonic anemometers are available from the authors.

  9. 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

  10. Wind turbine power performance measurement with the use of spinner anemometry

    DEFF Research Database (Denmark)

    Demurtas, Giorgio

    for power performance measurements. First development of spinner anemometer was related to calibration of yaw misalignment measurements. Here the first innovation was made in the spinner anemometer mathematical model, introducing a new calibration constant, kα =k1/k2. This constant was found to be directly...... related to measurements of inflow angle (yaw misalignment and flow inclination). The calibration of the constant was based on yawing the stopped turbine several times in and out of the wind comparing the varying inflow angle measurement with the yaw position sensor. The calibration for inflow angle...... is now used as default in commercial calibrations. To evaluate the power performance of a wind turbine with the use of spinner anemometry, an experiment was organized in collaboration with Romo Wind and Vattenfall. A met-mast was installed close to two wind turbines equipped with spinner anemometers...

  11. Full-Scale Spectrum of Boundary-Layer Winds

    DEFF Research Database (Denmark)

    Larsén, Xiaoli Guo; Larsen, Søren Ejling; Lundtang Petersen, Erik

    2016-01-01

    Extensive mean meteorological data and high frequency sonic anemometer data from two sites in Denmark, one coastal onshore and one offshore, have been used to study the full-scale spectrum of boundary-layer winds, over frequencies f from about 1 yr−1 to10 Hz. 10-min cup anemometer data are used...... to estimate the spectrum from about 1 yr−1 to 0.05 min−1; in addition, using 20-Hz sonic anemometer data, an ensemble of 1-day spectra covering the range 1 day−1 to 10 Hz has been calculated. The overlapping region in these two measured spectra is in good agreement. Classical topics regarding the various...... of the three velocity components over a wide range from 1 day−1 to 10 Hz, which is useful in determining the necessary sample duration when measuring turbulence statistics in the boundary layer....

  12. Hot film wall shear instrumentation for compressible boundary layer transition research

    Science.gov (United States)

    Schneider, Steven P.

    1992-01-01

    Experimental and analytical studies of hot film wall shear instrumentation were performed. A new hot film anemometer was developed and tested. The anemometer performance was not quite as good as that of commercial anemometers, but the cost was much less and testing flexibility was improved. The main focus of the project was a parametric study of the effect of sensor size and substrate material on the performance of hot film surface sensors. Both electronic and shock-induced flow experiments were performed to determine the sensitivity and frequency response of the sensors. The results are presented in Michael Moen's M.S. thesis, which is appended. A condensed form of the results was also submitted for publication.

  13. A system for remote measurements of the wind stress over the ocean

    Science.gov (United States)

    Large, William G.; Businger, J. A.

    1988-01-01

    The DISSTRESS system for remote measurements of the surface wind stress over the ocean from ships and buoys is described. It is fully digital, utilizing the inertial dissipation technique. Parallel processing allows anemometer data to be filtered in natural frequency space; that is, the filter cutoffs shift linearly with the mean wind speed of the data to be filtered. The construction of the digital Butterworth bandpass filters is presented in detail. The performance of the system is evaluated by analyzing the results from 28 days of operation during the Frontal Air-Sea Interaction Experiment. The mean wind speed is checked, the anemometer response function is established, and drag coefficients are compared to previous studies. The capability of the system is demonstrated by continuous time series of the friction velocity computed every 20 min. The conclusion is that the surface wind stress can be measured more reliably and accurately (20 percent) with this system than from anemometer wind speeds and a bulk formula.

  14. A laser velocimeter for remote wind sensing.

    Science.gov (United States)

    Lawrence, T. R.; Wilson, D. J.; Craven, C. E.; Jones, I. P.; Huffaker, R. M.; Thomson, J. A. L.

    1972-01-01

    A CW carbon dioxide laser Doppler radar has been developed and applied to remote measurement of atmospheric wind velocity and turbulence. The carbon dioxide laser illuminates residual particulate matter in the atmosphere. Radiation scattered by these particles is homodyned with a local oscillator to provide the Doppler signal. The performance of the instrument is verified by comparison of wind velocity data recorded simultaneously by the laser Doppler system and a cup-anemometer wind-vane system. All data comparisons indicate very close agreement of the two systems. Data inconsistencies are within the accuracy limitations of the conventional anemometer system. The range of the laser Doppler system during these tests was confined to approximately 30 m. Laser Doppler wind velocity data were observed at ranges exceeding 300 m; however, no conventional anemometer was set up at these ranges for data comparisons.

  15. Atmospheric turbulence affects wind turbine nacelle transferfunctions

    Energy Technology Data Exchange (ETDEWEB)

    St. Martin, Clara M.; Lundquist, Julie K.; Clifton, Andrew; Poulos, Gregory S.; Schreck, Scott J.

    2016-12-14

    Despite their potential as a valuable source of individual turbine power performance and turbine array energy production optimization information, nacelle-mounted anemometers have often been neglected because complex flows around the blades and nacelle interfere with their measurements. This work quantitatively explores the accuracy of and potential corrections to nacelle anemometer measurements to determine the degree to which they may be useful when corrected for these complex flows, particularly for calculating annual energy production (AEP) in the absence of other meteorological data. Using upwind meteorological tower measurements along with nacelle-based measurements from a General Electric (GE) 1.5sle model, we calculate empirical nacelle transfer functions (NTFs) and explore how they are impacted by different atmospheric and turbulence parameters. This work provides guidelines for the use of NTFs for deriving useful wind measurements from nacelle-mounted anemometers. Corrections to the nacelle anemometer wind speed measurements can be made with NTFs and used to calculate an AEP that comes within 1 % of an AEP calculated with upwind measurements. We also calculate unique NTFs for different atmospheric conditions defined by temperature stratification as well as turbulence intensity, turbulence kinetic energy, and wind shear. During periods of low stability as defined by the Bulk Richardson number (RB), the nacelle-mounted anemometer underestimates the upwind wind speed more than during periods of high stability at some wind speed bins below rated speed, leading to a more steep NTF during periods of low stability. Similarly, during periods of high turbulence, the nacelle-mounted anemometer underestimates the upwind wind speed more than during periods of low turbulence at most wind bins between cut-in and rated wind speed. Based on these results, we suggest different NTFs be calculated for different regimes of atmospheric stability

  16. A method for obtaining distributed surface flux measurements in complex terrain

    Science.gov (United States)

    Daniels, M. H.; Pardyjak, E.; Nadeau, D. F.; Barrenetxea, G.; Brutsaert, W. H.; Parlange, M. B.

    2011-12-01

    Sonic anemometers and gas analyzers can be used to measure fluxes of momentum, heat, and moisture over flat terrain, and with the proper corrections, over sloping terrain as well. While this method of obtaining fluxes is currently the most accurate available, the instruments themselves are costly, making installation of many stations impossible for most campaign budgets. Small, commercial automatic weather stations (Sensorscope) are available at a fraction of the cost of sonic anemometers or gas analyzers. Sensorscope stations use slow-response instruments to measure standard meteorological variables, including wind speed and direction, air temperature, humidity, surface skin temperature, and incoming solar radiation. The method presented here makes use of one sonic anemometer and one gas analyzer along with a dozen Sensorscope stations installed throughout the Val Ferret catchment in southern Switzerland in the summers of 2009, 2010 and 2011. Daytime fluxes are calculated using Monin-Obukhov similarity theory in conjunction with the surface energy balance at each Sensorscope station as well as at the location of the sonic anemometer and gas analyzer, where a suite of additional slow-response instruments were co-located. Corrections related to slope angle were made for wind speeds and incoming shortwave radiation measured by the horizontally-mounted cup anemometers and incoming solar radiation sensors respectively. A temperature correction was also applied to account for daytime heating inside the radiation shield on the slow-response temperature/humidity sensors. With these corrections, we find a correlation coefficient of 0.77 between u* derived using Monin-Obukhov similarity theory and that of the sonic anemometer. Calculated versus measured heat fluxes also compare well and local patterns of latent heat flux and measured surface soil moisture are correlated.

  17. Observational evidence for remote forcing of the west India coastal current

    Digital Repository Service at National Institute of Oceanography (India)

    Shetye, S.R.; Suresh, I.; Shankar, D.; Sundar, D.; Jayakumar, S.; Mehra, P.; Desai, R.G.P.; Pednekar, P.S.

    signif- icant at the 99% level (Table 2). The winds were measured at an interval of 10 minutes on the terrace of the National Institute of Oceanography in Dona Paula (see Figure 1). An earlier study [Aparna et al., 2005] has shown that these anemometer... shown ear- lier [Aparna et al., 2005], the vector correlation between the anemometer wind and QuikSCAT wind is significant; both yield the same direction for the wind, but the QuikSCAT wind has a higher magnitude. Though the QuikSCAT winds have a poorer...

  18. Sub-tidal water-level oscillations in the Mandovi estuary, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Shetye, S.R.; Vijith, V.

    in typical (Aparna et al., 2005) and average (Neetu et al., 2006) hodographs for the period. Aparna et al., 2005, also showed that the anemometer winds are significantly correlated with the winds measured by the QuikSCAT scatterometer; the QuikSCAT winds... for location of the anemometer used to measure winds) is shown in Figure 8. From the figure, we note that during the second half of March 2003 the winds did not have oscillations whose characteristics match with those of water level (Figure 6...

  19. Wind lidar evaluation at the Danish wind test site in Høvsøre

    DEFF Research Database (Denmark)

    Smith, D.A.; Harris, M.; Coffey, A.S.;

    2006-01-01

    Initial assessments of a wind lidar have shown the technology to have significant potential for wind field measurements in the wind energy industry. A more extended evaluation is now reported using a scanning lidar next to a meteorological mast with calibrated anemometers at the Risø wind test si...... in Høvsøre on the windy northwest coast of Denmark. Results are presented of wind speed comparisons at heights up to 100 m above ground level showing excellent correlation between the lidar and the cup anemometers. Copyright © 2006 John Wiley & Sons, Ltd....

  20. Simultaneous measurements of temperature, density, and pressure in a supersonic turbulent flow using laser-induced fluorescence

    Science.gov (United States)

    Mckenzie, R. L.; Gross, K. P.; Logan, P.

    1985-01-01

    A pulsed laser-induced fluorescence technique is described that provides simultaneous measurements of temperature, density, and pressure in low-temperature, turbulent flows. The measurements are made with spatial and temporal resolution comparable to that obtained with modern laser anemometer techniques used for turbulent boundary layer research. The capabilities of the method are briefly described and its demonstration in a simple two-dimensional turbulent boundary layer at Mach 2 is reported. The results are compared with conventional hot-wire anemometer data obtained in the same flow.

  1. ライン型流速センサの理論と特性

    OpenAIRE

    林, 秀千人; 児玉, 好雄

    1991-01-01

    The theory of the line-type hot wire anemometer to measuring the velocity profile at each time was given. The two theories of hot-wire anemometer, a constant temperature type and a constant current type were connected in this theory, and it was shown that the nonlinearity of relationship between the output of a hot-wire and the flow velocity was important. The parameters of line-type hot wire were examined, and it was found that a heating ratio k and parameters D, E have a very large influenc...

  2. Accuracy Of Hot-Wire Anemometry In Supersonic Turbulence

    Science.gov (United States)

    Logan, Pamela; Mckenzie, Robert L.; Bershader, Daniel

    1989-01-01

    Sensitivity of hot-wire probe compared to laser-induced-florescence measurements. Report discusses factors affecting readings of hot-wire anemometer in turbulent supersonic boundary layer. Presents theoretical analysis of responses of hot-wire probe to changes in flow; also compares measurements by hot-wire probe with measurements of same flows by laser-induced fluorescence (LIF). Because LIF provides spatially and temporally resolved data on temperature, density, and pressure, provides independent means to determine responses of hot-wire anemometers to these quantities.

  3. Atmospheric stability and turbulence fluxes at Horns Rev—an intercomparison of sonic, bulk and WRF model data

    DEFF Research Database (Denmark)

    Pena Diaz, Alfredo; Hahmann, Andrea N.

    2012-01-01

    Direct estimations of turbulent fluxes and atmospheric stability were performed from a sonic anemometer at 50 m height on a meteorological mast at the Horns Rev wind farm in the North Sea. The stability and flux estimations from the sonic measurements are compared with bulk results from a cup...... anemometer at 15 m height and potential temperature differences between the water and the air above. Surface flux estimations from the advanced weather research and forecast (WRF) model are also validated against the sonic and bulk data. The correlation between the sonic and bulk estimates of friction...

  4. Analysis of Signal-to-Noise Ratio of the Laser Doppler Velocimeter

    DEFF Research Database (Denmark)

    Lading, Lars

    1973-01-01

    The signal-to-shot-noise ratio of the photocurrent of a laser Doppler anemometer is calculated as a function of the parameters which describe the system. It is found that the S/N is generally a growing function of receiver area, that few large particles are better than many small ones, and that g......The signal-to-shot-noise ratio of the photocurrent of a laser Doppler anemometer is calculated as a function of the parameters which describe the system. It is found that the S/N is generally a growing function of receiver area, that few large particles are better than many small ones...

  5. A Tall-Tower Instrument for Mean and Fluctuating Velocity, Fluctuating Temperature and Sensible Heat Flux Measurements

    DEFF Research Database (Denmark)

    Gryning, Sven-Erik; Thomson, D. W.

    1979-01-01

    For an ongoing elevated-source, urban-scale tracer experiment, an instrument system to measure the three-dimensional wind velocity and the turbulent sensible heat flux was developed. The wind velocity was measured with a combination of cup anemometer, propeller (vertical) and vane sensor. The tem......For an ongoing elevated-source, urban-scale tracer experiment, an instrument system to measure the three-dimensional wind velocity and the turbulent sensible heat flux was developed. The wind velocity was measured with a combination of cup anemometer, propeller (vertical) and vane sensor...

  6. Power Performance Test on a Full-Scale Wind Turbine

    OpenAIRE

    Wangsness, Erik Brevik

    2014-01-01

    There is a standard made by the International Electrotechnical Commission (IEC) for how a power performance test on a full-scale wind turbine should be performed. By using this standard as a guideline, I have performed a power performance test on the 3 MW wind turbine at Valsneset. This was done by measuring the incoming wind towards the wind turbine rotor area with a lidar in conjunction with a cup anemometer at a 33 m high meteorological mast (met-mast). The lidar and cup anemometer measure...

  7. Application of short-range dual-Doppler lidars to evaluate the coherence of turbulence

    DEFF Research Database (Denmark)

    Cheynet, Etienne; Jakobsen, Jasna Bogunović; Snæbjörnsson, Jónas

    2016-01-01

    four days in May 2014 to monitor the wind field in the horizontal plane upstream of the bridge deck. Wind records obtained by five sonic anemometers mounted on the West side of the bridge are used as reference data. Single- and two-point statistics of wind turbulence are studied, with special emphasis...... on the root-coherence and the co-coherence of turbulence. A four-parameter decaying exponential function has been fitted to the measured co-coherence, and a good agreement is observed between data obtained by the sonic anemometers and the lidars. The root-coherence of turbulence is compared to theoretical...

  8. The fence experiment – full-scale lidar-based shelter observations

    DEFF Research Database (Denmark)

    Pena Diaz, Alfredo; Bechmann, Andreas; Conti, Davide

    2016-01-01

    We present shelter measurements of a fence from a field experiment in Denmark. The measurements were performed with three lidars scanning on a vertical plane downwind of the fence. Inflow conditions are based on sonic anemometer observations of a nearby mast. For fence-undisturbed conditions......, the lidars’ measurements agree well with those from the sonic anemometers and, at the mast position, the average inflow conditions are well described by the logarithmic profile. Seven cases are defined based on the relative wind direction to the fence, the fence porosity, and the inflow conditions...

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

    DEFF Research Database (Denmark)

    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......-off frequency similar to the lidar measurement frequency is applied to the sonic data. These results from the reconstructed wind are better than the maxima derived directly from the wind lidar measurements. However, the maxima of the raw sonic anemometer signal are still higher than the maxima...

  10. Meso- and Micro-scale modelling in China: Wind measurements at 12 meteorological stations in NE China (Dongbei)

    DEFF Research Database (Denmark)

    Lindelöw-Marsden, Petter; Enevoldsen, Karen

    This report is part of the presentation of the results obtained during the CMA component of the Wind Energy Development (WED) program. It describes the techniques and results of the project “A02 Measurements” which produced wind measurements from mast mounted anemometers and vanes in Dongbei in N...... in North-East China during 2008 to 2010. Main focus is given to the equipment supplied by Risø and the measurements taken by these systems. Specifically it shows the results of a comparison between the P2546A and EL15-1A cup anemometer....

  11. Reduction of noise and bias in randomly sampled power spectra

    DEFF Research Database (Denmark)

    Buchhave, Preben; Velte, Clara Marika

    2015-01-01

    We consider the origin of noise and distortion in power spectral estimates of randomly sampled data, specifically velocity data measured with a burst-mode laser Doppler anemometer. The analysis guides us to new ways of reducing noise and removing spectral bias, e.g., distortions caused by modific......We consider the origin of noise and distortion in power spectral estimates of randomly sampled data, specifically velocity data measured with a burst-mode laser Doppler anemometer. The analysis guides us to new ways of reducing noise and removing spectral bias, e.g., distortions caused...

  12. Electro-Optical/Meteorological Simulation Model

    Science.gov (United States)

    1985-08-01

    Hair Hygrometer % t5% Dewpoint Lithium-Chloride 0C +I OC Wind Speed at 10m and 2m Cup Anemometer msec-I t2% Rain Rate --- mmhr-I Rainfall --- mmhr- 1...for both the 10 and 2 meter cup an mometer is 0.8 msec- 1 . There is no effective way to distinguish between wind speeds of calm and 1 msec...each other or the opposing variable. Even though the 10m and 2m winds both measure wind speed, measurements are from two separate anemometers , so the

  13. Variations in long term wind speed during different decades in Arabian Sea and Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    SanilKumar, V.; Philip, C.S.

    height every 3 h intervals. Each 3 hourly wind observation is a 10-minute average wind speed and direction sampled at 1 Hz by a cup anemometer with vane made by Lambercht. The accuracy of wind speed measurements is 1.5% of full scale (0–60m s −1...

  14. Environmental controls on the seasonal carbon dioxide fluxes in the northeastern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Sardessai, S.; Maya, M.V.; Shetye, S.; PrasannaKumar, S.; Fernandes, V.; Paul, J.; Ramaiah, N.

    to dusk. The wind speed was measured by using the hand held anemometer (portable net kit, dyna lab, Pune). Results and Discussion Open ocean The thermal structure (Fig. 2a) shows the eddie pumping of the subsurface water mass to shallower depths...

  15. The measurement of the material parameters of viscoelastic fluids using a rotating sphere and a rheogoniometer

    NARCIS (Netherlands)

    Acharya, A.; Maaskant, P.

    1978-01-01

    In this work, measurement of the flow field around a rotating sphere has been used to obtain the material parameters of a second-order Rivlin-Ericksen fluid. Experiments were carried out with a Laser-Doppler anemometer to obtain the velocity distribution and usingGiesekus' analysis, the material par

  16. Turbulence Amplification with Incidence at the Leading Edge of a Compressor Cascade

    Directory of Open Access Journals (Sweden)

    Garth V. Hobson

    1999-01-01

    Full Text Available Detailed measurements, with a two-component laser-Doppler velocimeter and a thermal anemometer were made near the suction surface leading edge of controlled-diffusion airfoils in cascade. The Reynolds number was near 700,000, Mach number equal to 0.25, and freestream turbulence was at 1.5% ahead of the cascade.

  17. Spatial distribution of upwelling off the central east coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, T.V.N.

    at the offshore stations for the sections I–V were observed winds using con- ventional anemometer on board the Research Vessel Gaveshani (≅10 m above the sea surface) during the stay at the hydrographic stations covered in 13–28 March 1988 and 23 August–7...

  18. Trends of wave height and period in the Central Arabian Sea from 1996 to 2012: A study based on satellite altimeter data

    Digital Repository Service at National Institute of Oceanography (India)

    Hithin, N.K.; SanilKumar, V.; Shanas, P.R.

    measures wind speed at 3 m above the sea surface and SWH at a 3-h interval. Wind observation is a 10-minute average with wind speed and direction sampled at 1 Hz by a cup anemometer with vane. The accuracy of wind speed measurements is 1.5% of full scale...

  19. Insects of terrestrial origin over Indian Ocean during north-east monsoon

    Digital Repository Service at National Institute of Oceanography (India)

    Pathak, S.C.; Kulshrestha, V.; Choubey, A.K.; Parulekar, A.H.

    with portable anemometers (OGAWA SEIKI, Japan) and corrected for ·the ship speed and direction of movement using standard tables. Generalised wind flow patterns (Figure 1) were then drawn using these readings and the records of wind direction in the study area...

  20. Observational evidence from direct current measurements for propagation of remotely forced waves on the shelf off the west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Amol, P.; Shankar, D.; Aparna, S.G.; Shenoi, S.S.C.; Fernando, V.; Shetye, S.R.; Mukherjee, A.; Agarvadekar, Y.; Khalap, S.; Satelkar, N.P.

    QuikSCATwindvectorcorrelateswellwiththewindmeasuredusing an anemometer on the Indian west coast. Gridded data at a resolution of 0.5 were downloaded from http://www.ifremer.fr/cersat/en/data/download/download.htm. The winds were rotated using the average angle of the coast based on the QuikSCAT grid. 5 3 Alongshore...

  1. CO2 supersaturation and net heterotrophy in a tropical estuary (Cochin, India): Influence of anthropogenic effect - Carbon dynamics in tropical estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Gupta, G.V.M.; Thottathil, S.D.; Balachandran, K.K.; Madhu, N.V.; Madeswaran, P.; Nair, S.

    is proportional to Sc -0.5 . Sc was computed for a given salinity (Wanninkhof 1992), assuming that Sc varies linearly with salinity. Wind speed data was collected from a hand held anemometer (Lutron, AM4201). Water currents were extracted from 2D hydrodynamic...

  2. Sea level changes induced by local winds on the west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Mehra, P.; Tsimplis, M.N.; Desai, R.G.P.; Joseph, A.; Shaw, A.G.P.; Somayajulu, Y.K.; Cipollini, P.

    using the average angle of orientation of the coast in the vicinity of the anemometer (~-12 degrees w.r.t. North). The pressure sensor based tide gauge data used in the present study is from January-December 2007 at an hourly interval...

  3. November 2009 tropical cyclone Phyan in the eastern Arabian Sea: Oceanic response along west India coast and Kavaratti lagoon

    Digital Repository Service at National Institute of Oceanography (India)

    Joseph, A.; Desai, R.G.P.; Mehra, P.; VijayKumar, K.; Agarvadekar, Y.; Ryan, L.; Rivankar, P.; Viegas, B.

    large gust factor (~30) during peak cyclone winds is a contradiction. Perhaps, the presence of coconut palms in the vicinity of the anemometer must have contributed in some way to the observed fairly large gust factor. As noted in [2], these results...

  4. Estimation of bulk transfer coefficient for latent heat flux (Ce)

    Digital Repository Service at National Institute of Oceanography (India)

    Sadhuram, Y.

    specific humidity at sea surface tempera- ture, qn is the specific humidity at deck level, and U is the wind speed at the height of anemometer. All the available data in each area and along the boundaries are used to compute E. NFD and Ce. 3. Results...

  5. Errors in second moments estimated from monostatic Doppler sodar winds. II. Application to field measurements

    DEFF Research Database (Denmark)

    Gaynor, J. E.; Kristensen, Leif

    1986-01-01

    For pt.I see ibid., vol.3, no.3, p.523-8 (1986). The authors use the theoretical results presented in part I to correct turbulence parameters derived from monostatic sodar wind measurements in an attempt to improve the statistical comparisons with the sonic anemometers on the Boulder Atmospheric ...

  6. A particle detector for use in ventilation engineering.

    Science.gov (United States)

    Clark, R P

    1973-09-01

    An electronic particle counting device is described, based on a constant-temperature hot-wire anemometer probe. The device has found application in tracing the motions of droplets and measuring their concentration within ventilated areas when subjected to different types of ventilation. In this way the effectiveness of various systems may be determined.

  7. The calibration of (multi-) hot-wire probes. 1. Temperature calibration

    NARCIS (Netherlands)

    Dijk, van A.; Nieuwstadt, F.T.M.

    2004-01-01

    We study the performance of the classical relation for the correction for ambient temperature drift of the signal of a hot-wire anemometer and the influence of practical assumptions. It is shown that most methods to estimate the operational temperature via the temperature/resistance coefficient lead

  8. West Closure Complex Pump Intake Model, New Orleans, Louisiana

    Science.gov (United States)

    2013-02-01

    Doppler Velocimetry (LDV), ERDC/CHL TR-13-1 63 hot - wire anemometry , miniature propeller meter, and using a differential pressure cell with a...of a hot - wire anemometer. The minia- ture propeller meter has been used by some investigators and was discussed in Sweeney and Rockwell (1982). Use

  9. Velocity Profile Characterization for the 5-CM Agent Fate Wind Tunnels

    Science.gov (United States)

    2008-01-01

    tunnel validation) and the HD on sand test phases of the Agent Fate Program. 15. SUBJECT TERMS Hot wire anemometry Boundary layer Evaporation Agent...TSI Hot Wire Probe ........................................................................ 31 21. TSI IFA 300 Thermal Anemometry Systems...Characterization Instrumentation 5.2.1 Hot Wire Anemometers 5.2.1.1 Overview Hot Wire Anemometry Several techniques were considered to measure the velocity

  10. Rotorcraft Brownout: Advanced Understanding, Control and Mitigation

    Science.gov (United States)

    2008-12-31

    sediment bed. Evaluation of the spatial structure of an impinging flow of known source intensity is achieved with a 3D hot - wire anemometer. Following...iv) Purchase of equipment to upgrade the wind-tunnel anemometry system, v) Purchase of materials (particles) for use in wind tunnel

  11. Low-Speed Wind Tunnel Flow Quality Determination

    Science.gov (United States)

    2011-09-01

    Hot Wire Anemometry (HWA/CTA) System..................................17 a. Cable Length, S3...transducers. 5. Hot Wire Anemometry (HWA/CTA) System A Dantec Constant Temperature Anemometer (CTA) system comprised of three 56C01 CTA modules...component hot wire (CTA), the wall boundary layer characteristics consisting of the velocity profile, streamwise turbulence intensity, and spectral energy

  12. Winnebago Resource Study. Cooperative Research and Development Final Report, CRADA Number CRD-09-329

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez, A. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Robichaud, R. [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2015-03-01

    Since 2005 the NREL Native American Tall Tower Loan program has assisted Native American tribes to assess their wind resource by lending tall (30m - 50m) anemometer. This program has allowed tribes a lower risk way to gather financeable wind data for potential utility scale wind energy projects. These projects offer Tribes a significant economic development opportunity.

  13. Performance evaluation of an all-fiber image-reject homodyne coherent Doppler wind lidar

    DEFF Research Database (Denmark)

    Foroughi Abari, Farzad; Pedersen, A. T.; Dellwik, Ebba

    2015-01-01

    a sonic anemometer, as the reference instrument. The measurements clearly show that the image-reject architecture results in more accurate measurements of radial wind velocities close to zero. Close-to-zero velocities are usually associated with the vertical component of the wind and are important...

  14. The Bolund experiment - design of measurement campaign using CFD

    DEFF Research Database (Denmark)

    Bechmann, Andreas; Johansen, Jeppe; Sørensen, Niels N.

    the upcoming measurement campaign. The simulation results are used for estimating rational positions of measuring masts and instrumentation. A total of ten measuring masts are proposed consisting of two 16 m masts, six 9 m masts and two 5 m masts. The masts are instrumented with 12 cup anemometers for mean...

  15. Power curve investigation

    DEFF Research Database (Denmark)

    Villanueva, Héctor; Gómez Arranz, Paula

    This report describes the analysis carried out with data from a given turbine in a wind farm and a chosen period. The purpose of the analysis is to correlate the power output of the wind turbine to the wind speed measured by a nacelle-mounted anemometer. The measurements and analysis are not perf...

  16. Hot film anemometry. Citations from the NTIS data base

    Science.gov (United States)

    Habercom, G. E., Jr.

    1980-08-01

    The principles of hot film anemometer operation are summarized; wind tunnel and laboratory tests are described; flow field dynamics are discussed involving turbulence, boundary layers, separation, shock waves, and stresses; mathematical models and analysis are presented; computer techniques are outlined; and a number of applications are given. This updated bibliography contains 58 citations, 3 of which are new entries to the previous edition.

  17. The model chain and the full scale spectrum of the boundary layer wind

    DEFF Research Database (Denmark)

    Larsén, Xiaoli Guo; Lundtang Petersen, Erik; Larsen, Søren Ejling

    and high frequency sonic anemometer data from the 100m meteorological mast at Danish test station Høvsøre. Datasets from the offshore wind farm Horns Rev were also analyzed. The conclusions from the analysis are given below. In the present study we complement and extend the analysis using a new dataset...

  18. Inclined test of nacelle wind lidar

    DEFF Research Database (Denmark)

    Courtney, Michael

    A nacelle wind lidar, placed at ground level, is tested by inclining the laser beams to bisect a measurement mast at a known distance and height. The horizontal wind speed reported by the lidar is compared to a reference cup anemometer mounted on the mast at the comparison height....

  19. Lidar measurements of plume statistics

    DEFF Research Database (Denmark)

    Ejsing Jørgensen, Hans; Mikkelsen, T.

    1993-01-01

    the source, instantaneous crosswind plume profiles were detected repetitively at high spatial (1.5 m) and temporal (3 sec) intervals by use of a mini LIDAR system. The experiments were accompanied by measurement of the surface-layer mean wind and turbulence quantities by sonic anemometers. On the basis...

  20. Improved interpretation and validation of CFD predictions

    DEFF Research Database (Denmark)

    Popiolek, Z.; Melikov, Arsen Krikor

    2004-01-01

    The mean velocity in rooms predicted by CFD simulations based on RANS equations differs from the mean (in time) magnitude of the velocity, i.e. the mean speed, in rooms measured by low velocity thermal anemometers with omnidirectional sensor. This discrepancy results in incorrect thermal comfort ...

  1. Micrometeorological Characterization of the Mace Head Field Station during PARFORCE

    NARCIS (Netherlands)

    Kunz, G.J.; Leeuw, G. de

    2000-01-01

    Micrometeorological flux packages, consisting of 3D ultrasonic anemometers and an IR water vapour sensor, each sampling at a rate of 20 Hz, were used to characterise turbulent transport properties at the Mace Head Research Station during PARFORCE experiments in 1998 and 1999. Micrometeorological par

  2. Bi-directional fast flow sensor with a large dynamic range

    NARCIS (Netherlands)

    Bree, de Hans-Elias; Jansen, Henri V.; Lammerink, Theo S.J.; Krijnen, Gijs J.M.; Elwenspoek, Miko

    1998-01-01

    In this article an extended mass-flow sensor is presented. Apart from the magnitude of the flow, as an add-on to the traditional anemometer, this sensor also measures the direction of the flow. This is of interest for the flow sensor market in general, and more in particular for the safety monitorin

  3. Experimental and theoretical study of the atmospheric boundary layer over the paris area; Etude experimentale et theorique de la couche limite atmospherique en agglomeration parisienne

    Energy Technology Data Exchange (ETDEWEB)

    Menut, L

    1997-12-15

    This thesis studied the urban boundary layer dynamic behaviour over the Paris area by comparing urban (Paris) and suburban (Palaiseau) dynamic data such as lidars, sodars, sonic anemometers. All the data were obtained during the ECLAP experiment, specifically performed to characterize the differences between a city and its near environment. (author)

  4. Report on characteristics of WMO47 Metadata

    OpenAIRE

    1995-01-01

    This report summarises the ship instrumentation information contained in the WMO publication 'International list of selected, supplementary and auxiliary ships' between 1973 and 1994. The information from this publication has been converted to an electronic format and trends in instrumentation type and anemometer and platform heights documented. The format of the new datafile is described.

  5. Addressing Spatial Variability of Surface-Layer Wind with Long-Range WindScanners

    DEFF Research Database (Denmark)

    Berg, Jacob; Vasiljevic, Nikola; Kelly, Mark C.;

    2015-01-01

    This paper presents an analysis of mean wind measurements from a coordinated system of long-range WindScanners. From individual scan patterns the mean wind field was reconstructed over a large area, and hence it highlights the spatial variability. From comparison with sonic anemometers, the quality...

  6. The Coastal Environmental Reference Service, Retrieval Program Users Guide.

    Science.gov (United States)

    1981-10-01

    GAUGE 02008 TIDE GAUGE 03001 VISUAL ESTIMATE 03002 SURFACE DRIFTER 03003 MID-DEPTH DRIFTER 03004 BOTTOM DRIFTER 03005 DYE PATCH 03006 SAVONIUS ROTOR...04001 IMPELLOR ANEMOMETER 04002 SAVONIUS ROTOR 04003 DIRECTION VANE 04004 ESTIMATE 04005 RAM-AIR-PRESSURE MTR 04006 VORTEX FREQUENCY MTR 04007 TRIPLE

  7. Characterization of Airborne Permethrin During the Manufacture of Army Combat Uniforms Using Pre-Treated Fabric

    Science.gov (United States)

    2016-08-01

    using a TSI VelociCalc® 9545-A thermal anemometer. Air change calculations were based on total exhaust air flow out of the facility by measuring air...Solvent Resistant Teflon-Silicone Coated Septa A.5.1.6 3mm-4mm borosilicate glass beads A.5.2 Soxhlet. A.5.2.1 Electric heater with variable

  8. Thermal flow micro sensors

    NARCIS (Netherlands)

    Elwenspoek, M.

    1999-01-01

    A review is given on sensors fabricated by silicon micromachining technology using the thermal domain for the measurement of fluid flow. Attention is paid especially to performance and geometry of the sensors. Three basic types of thermal flow sensors are discussed: anemometers, calorimetric flow se

  9. Reconstruction of 3D flow structures in a cylindrical cavity with a rotating lid

    DEFF Research Database (Denmark)

    Meyer, Knud Erik

    will also be based on time-resolved stereoscopic PIV measurements in a vertical plane through the cylinder axis as shown in figure 1. Compared to Meyer et al (2008) the measurements will be expanded by adding measurements in several points outside the PIV data plane with a Laser Doppler Anemometer (LDA...

  10. An overview of MADONA: A multinational field study of high-resolution meteorology and diffusion over complex terrain

    DEFF Research Database (Denmark)

    Cionco, R.M.; aufm Kampe, W.; Biltoft, C.;

    1999-01-01

    and aerosol sensors and four source generators were used during each day of the field study. This array of sensors included 14 towers of wind cups and vanes, 10 sonic anemometer/thermometers, one boundary layer sonde, two lidar, one ion sensor, the CEDE Weather Station, and several one-of-a-kind sensors...

  11. MIZEX (Marginal Ice Zone Program): A Program for Mesoscale Air-Ice-Ocean Interaction Experimemts om Arctic Marginal Ice Zones. V. MIZEX 84. Summer Experiment PI (Principal Investigator) Preliminary Reports,

    Science.gov (United States)

    1984-10-01

    effort directed by Jay Ardai and Al Hielscher plus expert flying by Giles Porter of Luft 30 -7 Transport. The same instrument was redeployed on floe C2...momentum and heat fluxes across the air- ice- interface were measured by an ultrasonic anemometer-thermometer (Kaiyo4 Denki) at the boom of the bow

  12. Oscillations in a Forward-Facing Cavity Measured Using Laser-Differential Interferometry in a Hypersonic Quiet Tunnel

    Science.gov (United States)

    2007-12-11

    Feedback Stabilization System . . . . . . . . . . . . . . . . . . . . . . 48 4 Results...a) induced vibration profile, b) induced vibration power spectrum . . . . 49 3.21 Schematic of feedback -stabilized LDI...Boeing/AFOSR Mach-6 Quiet Tunnel BFL Back Focal Length xvi CCA Constant Current Anemometer EFL Effective Focal Length FFC Forward Facing Cavity LDI Laser

  13. The Effect of a Finite Measurement Volume on Power Spectra from a Burst Type LDA

    DEFF Research Database (Denmark)

    Buchhave, Preben; Velte, Clara Marika; K. George, William

    2014-01-01

    We analyze the effects of a finite size measurement volume on the power spectrum computed fromdata acquired with a burst-type laser Doppler anemometer. The finite measurement volume causes temporal distortions in acquisition of the data resulting in phenomena such as finite processing time and de...

  14. Emissions Control in Swirl Stabilized Spray Combusters, an Experimental and Computational Study

    Science.gov (United States)

    2007-02-01

    flows is important for properly modeling them. Constant temperature anemometer was used to measure the spectra of the confined turbulent swirling flow...of Gas Turbine Swirl Cup Dynamics, Part 5: Large Eddy Simulations of Cold Flow,"-AIAA-2003-6105, 2003, Reno, NV. 11. Cannon, S. M., and Smith, C. E

  15. Emergency Protection from Aerosols

    Science.gov (United States)

    1981-07-01

    tape), 3. flour in a clean bag (the first test u,.i 5 lb of flour, and the second test used only 1 cup , 18 4. clean bag in the sweeper cannister with...the buildup of spore concentrations inside the house. A sensitive anemometer and a recording wind-direction instrument were erected on a 2-m pole

  16. A Case Study of Wind Resource Assessment on a High-Rise Building

    Science.gov (United States)

    Padrick, S.; Clements, C. B.; Seto, D.

    2009-12-01

    There has been a recent surge in the development of small-scale wind turbines for wind energy on buildings in urban areas. This requires knowledge of wind characteristics on specific buildings. A short measurement campaign was conducted during a three-month period on the Department of Meteorology’s rooftop observatory located at San José State University, in downtown San Jose, CA to determine the potential for use of small-scale turbines on campus. Cup and prop-vane anemometers were configured around the roof at each corner of the building and in the center of the roof at heights of 1-1.5 m above the roof. A single prop-vane anemometer was also located on a tower at 10 m above the roof surface. This arrangement was used to determine areas of reduced flow in order to measure the potential placement of small turbines on roofs of similar dimensions. In addition to the cup anemometers, two 3-d sonic anemometers were placed on the upwind edge of the building to determine the effects of turbulence on the flow over the roof. Preliminary results indicate that winds at each corner of the building did not differ much, but were on average about 1-2 m s-1 less in magnitude than winds at 10 m above the roof surface. This paper will present results on the turbulence statistics obtained from the field campaign and the wind power potential on this particular building and geometry.

  17. Telltale wind indicator for the Mars Phoenix lander

    DEFF Research Database (Denmark)

    Gunnlaugsson, H.P.; Honstein-Rathlou, C.; Merrison, J.P.

    2008-01-01

    The Telltale wind indicator is a mechanical anemometer designed to operate on the Martian surface as part of the meteorological package on the NASA Phoenix lander. It consists of a lightweight cylinder suspended by Kevlar fibers and is deflected under the action of wind. Imaging of the Telltale...

  18. A strategy to eliminate all nonlinear effects in constant-voltage hot-wire anemometry.

    Science.gov (United States)

    Berson, Arganthaël; Blanc-Benon, Philippe; Comte-Bellot, Geneviève

    2009-04-01

    A constant-voltage anemometer is subject to nonlinear effects when the operating hot wire is exposed to large velocity fluctuations in the incident flow. This results in the generation of undesirable higher harmonics, just as in the two classic systems, constant-current and constant-temperature anemometers, for which no attempts are normally made to correct the nonlinearities. The present investigation shows that these undesirable higher harmonics can be suppressed in the case of a constant-voltage anemometer. A new approach to process experimental data is proposed. It is based on three explicit equations established and solved with all terms included, i.e., without linearization. These are (1) the first-order differential equation that describes the electronic circuit of a constant-voltage anemometer-this equation permits to deduce the instantaneous resistance of the hot wire from the output voltage of the anemometer; (2) the first-order differential equation that expresses the thermal lag behavior of the hot wire when used in a constant-voltage mode-this equation permits to restore the instantaneous resistance that an ideal wire would have without thermal inertia in the same flow conditions; and (3) the algebraic relation that expresses the heat-transfer law of an ideal wire, according to King's law, a look-up table, or a polynomial fit-this relation permits to deduce the instantaneous flow velocity from the instantaneous resistance of the ideal wire. The proposed method is easily implemented on a personal computer and permits odd turbulence moments, such as skewness factors, to be obtained satisfactorily.

  19. 风速仪在起重机上的应用

    Institute of Scientific and Technical Information of China (English)

    张军

    2014-01-01

    介绍了风速仪在起重机上使用,针对以往起重机上风速仪应用效果不佳问题,指出了应按照起重机不同的使用风况和不同的风速仪安装高度,并结合风速仪输出的实际风速值来进行整定。%The paper introduces application of anemometerin cranes,and puts forward its installation height required in different wind conditions and for different kinds of anemometers considering previous cases with poor application effects of anemographs in cranes.The installation height shall be adjusted according the actual wind speed outputted by the anemome-ter.

  20. Momentum and Turbulent Kinetic Energy Budgets Within the Park Avenue Street Canyon During the Joint Urban 2003 Field Campaign

    Science.gov (United States)

    Nelson, Matthew A.; Pardyjak, Eric R.; Klein, Petra

    2011-07-01

    Very few attempts have so far been made to quantify the momentum and turbulent kinetic energy (TKE) budgets within real urban canopies. In this study, sonic anemometer data obtained during the Joint Urban 2003 field campaign in Oklahoma City, U.S.A. were used for calculating the momentum and TKE budgets within a real-world urban street canyon. Sonic anemometers were deployed on multiple towers in the lower half of the canyon. Gradients in all three principal directions were included in the analyses. The storage and buoyancy terms were found to have negligible contributions to both the momentum and TKE budgets. The momentum budgets were generally found to be more complex than a simple balance of two physical processes. The horizontal terms were found to have significant and sometimes dominant contributions to the momentum and TKE budgets.

  1. Uncertainties in hot-wire measurements of compressible turbulent flows implied by comparisons with laser-induced fluorescence

    Science.gov (United States)

    Mckenzie, R. L.; Logan, P.

    1986-01-01

    A hot-wire anemometer and a new nonintrusive laser-induced fluorescence (LIF) technique are used to survey a Mach 2 turbulent boundary layer. The hot-wire anemometer's ability to accurately measure mass flux, temperature, and density fluctuations in a compressible flow is examined by comparing its results with those obtained using LIF. Several methods of hot-wire calibration are used, and the uncertainties in their measurements of various fluctuating flow parameters are determined. The results show that although a hot-wire operated at high overheat can measure mass flux fluctuations, temperature and density fluctuations are not determined accurately from such measurements. However, a hot-wire operated at multiple overheats can be used to measure static and total temperature fluctuations. The presence of pressure fluctuations and their correlation with density can prevent the use of hot-wire data to determine density fluctuations.

  2. A detailed procedure for measuring turbulent velocity fluctuations using constant-voltage anemometry

    Science.gov (United States)

    Mohammed-Taifour, Abdelouahab; Weiss, Julien; Sadeghi, Atabak; Vétel, Jérôme; Jondeau, Emmanuel; Comte-Bellot, Geneviève

    2015-09-01

    A detailed procedure to use a constant-voltage anemometer (CVA) for the accurate measurement of turbulent flows is proposed. The procedure is based on the usual small-perturbation analysis of hot-wire signals. It consists in three steps: (1) the calibration of internal elements, required to estimate the two main electrical parameters of the CVA circuitry that are needed in the data analysis, (2) a flow calibration to relate the CVA output voltage and the hot-wire time constant to the flow velocity, and (3) a data-processing algorithm to recover the fluctuating flow quantities from the output voltage. The procedure is tested in two classical turbulent flows: a zero-pressure-gradient boundary layer and a round jet. In both cases, the CVA results are shown to be essentially indistinguishable from the results obtained with a research-grade constant-temperature anemometer.

  3. Flow Characterization of a Piezo-Electric High Speed Valve

    Directory of Open Access Journals (Sweden)

    T. Takiya

    2012-03-01

    Full Text Available Injecting a gas into fusion reactors or semiconductor manufacturing systems, one has to quickly control the flow rate by a piezoelectric valve. In order to construct a gas injection system with high speed valves in the future, performance tests have been conducted on a commercial piezoelectric valve. An orifice flowmeter for measuring time average flowrate and a hot wire anemometer for instantaneous flowrate were manufactured. The total flow coefficient of the orifice flowmeter was obtained experimentally under a low pressure of a 10-2 Pa and a low flowrate of a few mg/s, although they are smaller than the values specified by Japanese Industrial Standards. It is found that the hot wire anemometer installed downstream in the vicinity of the valve is suitable for detecting the change in flowrate with the response time of less than 1 ms.

  4. A pulsed wire probe for the measurement of velocity and flow direction in slowly moving air.

    Science.gov (United States)

    Olson, D E; Parker, K H; Snyder, B

    1984-02-01

    This report describes the theory and operation of a pulsed-probe anemometer designed to measure steady three-dimensional velocity fields typical of pulmonary tracheo-bronchial airflows. Local velocities are determined by measuring the transport time and orientation of a thermal pulse initiated at an upstream wire and sensed at a downstream wire. The transport time is a reproducible function of velocity and the probe wire spacing, as verified by a theoretical model of convective heat transfer. When calibrated the anemometer yields measurements of velocity accurate to +/- 5 percent and resolves flow direction to within 1 deg at airspeeds greater than or equal to 10 cm/s. Spatial resolution is +/- 0.5 mm. Measured flow patterns typical of curved circular pipes are included as examples of its application.

  5. Characterization of particles in the Langley 0.3 meter transonic cryogenic tunnel using hot wire anemometry

    Science.gov (United States)

    Singh, J. J.; Marple, C. G.; Davis, W. T.

    1982-01-01

    Hot wire anemometry was used to identify the nature of particles reportedly observed during free stream velocity measurements in the Langley 0.3-meter transonic cryogenic tunnel using a Laser Doppler Velocimeter. Since the heat-transfer process from the hot wire depends on the thermal conductivity and sticking capability of the particles, it was anticipated that the hot wire anemometer response would be affected differently upon impaction by liquid droplets and solid aerosols in the test gas stream. Based on the measured time response of the hot-wire anemometer in the cryogenic tunnel operated in the 0.3-0.8 Mach number range, it is concluded that the particles impacting the hot wire are liquid in nature rather than solid aerosols. It is further surmised that the liquid aerosols are unevaporated liquid nitrogen droplets used for cooling the tunnel test gas.

  6. CFD Calculations of the Flow Around a Wind Turbine Nacelle

    Energy Technology Data Exchange (ETDEWEB)

    Varela, J.; Bercebal, D. [Ciemat, Madrid (Spain)

    2000-07-01

    The purpose of this work is to identify the influence of a MADE AE30 wind turbine nacelle on the site calibration anemometer placed on the upper back of the nacelle by means of flow simulations around the nacelle using FLUENT, a Commercial Computational Fluid Dynamics code (CFD), which provides modeling capabilities for the simulation of wide range laminar and turbulent fluid flow problems. Different 2D and 3D simulations were accomplished in order to estimate the effects of the complex geometry on the flow behavior. The speed up and braking values of the air flow at the anemometer position are presented for different flow conditions. Finally some conclusions about the accuracy of results are mentioned. (Author) 5 refs.

  7. A six-beam method to measure turbulence statistics using ground-based wind lidars

    DEFF Research Database (Denmark)

    Sathe, Ameya; Mann, Jakob; Vasiljevic, Nikola

    2015-01-01

    A so-called six-beam method is proposed to measure atmospheric turbulence using a ground-based wind lidar. This method requires measurement of the radial velocity variances at five equally spaced azimuth angles on the base of a scanning cone and one measurement at the centre of the scanning circle...... lidar (WindScanner), and the derived turbulence statistics (using both methods) such as the u and v variances are compared with those obtained from a reference cup anemometer and a wind vane at 89m height under different atmospheric stabilities. The measurements show that in comparison to the reference...... cup anemometer, depending on the atmospheric stability and the wind field component, the six-beam method measures between 85 and 101% of the reference turbulence, whereas the VAD method measures between 66 and 87% of the reference turbulence....

  8. A six-beam method to measure turbulence statistics using ground-based wind lidars

    DEFF Research Database (Denmark)

    Sathe, Ameya; Mann, Jakob; Vasiljevic, Nikola

    2014-01-01

    A so-called six-beam method is proposed to measure atmospheric turbulence using a ground-based wind lidar. This method requires measurement of the radial velocity variances at five equally spaced azimuth angles on the base of a scanning cone and one measurement at the center of the scanning circle...... lidar (WindScanner), and the derived turbulence statistics (using both methods) such as the u and v variances are compared with those obtained from a reference cup anemometer and a wind vane at 89m height under different atmospheric stabilities. The measurements show that in comparison to the reference...... cup anemometer, depending on the atmospheric stability and the wind field component, the six-beam method measures between 85–101% of the reference turbulence, whereas the VAD method measures between 66–87% of the reference turbulence....

  9. Generic Methodology for Field Calibration of Nacelle-Based Wind Lidars

    DEFF Research Database (Denmark)

    Borraccino, Antoine; Courtney, Michael; Wagner, Rozenn

    2016-01-01

    by the geometry of the scanning trajectory and the lidar inclination. The line-of-sight velocity is calibrated in atmospheric conditions by comparing it to a reference quantity based on classic instrumentation such as cup anemometers and wind vanes. The generic methodology was tested on two commercially developed...... lidars, one continuous wave and one pulsed systems, and provides consistent calibration results: linear regressions show a difference of ∼0.5% between the lidar-measured and reference line-of-sight velocities. A comprehensive uncertainty procedure propagates the reference uncertainty to the lidar...... measurements. At a coverage factor of two, the estimated line-of-sight velocity uncertainty ranges from 3.2% at 3 m·s-1 to 1.9% at 16 m·s-1. Most of the line-of-sight velocity uncertainty originates from the reference: the cup anemometer uncertainty accounts for 90% of the total uncertainty. The propagation...

  10. Offshore wind profiling using light detection and ranging measurements

    DEFF Research Database (Denmark)

    Pena Diaz, Alfredo; Hasager, Charlotte Bay; Gryning, Sven-Erik;

    2009-01-01

    The advantages and limitations of the ZephlR (R), a continuous-wave, focused light detection and ranging (LiDAR) wind profiler, to observe offshore winds and turbulence characteristics were tested during a 6 month campaign at the tronsformer/platform of Hams Rev, the world's largest wind form....... The LiDAR system is a ground-based sensing technique which avoids the use of high and costly meteorological masts. Three different inflow conditions were selected to perform LiDAR wind profiling. Comparisons of LiDAR mean wind speeds against cup anemometers from different masts showed high correlations...... for the open sea sectors and good agreement with their longitudinal turbulence characteristics. Cup anemometer mean wind speed profiles were extended with LiDAR profiles up to 161 m on each inflow sector. The extension resulted in a good profile match for the three surrounding masts. These extended profiles...

  11. Supplementary measurements on the Guetsch - Model validation / Monitoring the wind power installation / Icing-up; Zusatzmessungen am Guetsch: Modell-Validierung / Monitoring der Windkraftanlage / Vereisung

    Energy Technology Data Exchange (ETDEWEB)

    Cattin, R.

    2002-07-01

    This final report for the Swiss Federal Office of Energy (SFOE) documents the results of additional wind measurements made on the Guetsch mountain in the Swiss Alps in Spring 2002. The results of measurements made with heated and non-heated anemometers at the Guetsch weather station and using SODAR at the existing wind turbine site are compared and the discrepancies found discussed. The report also presents findings on the vertical wind profiles at the site, which are dependent on the main direction of the wind. The results of the measurements are compared with calculations made using the fluid-dynamics model developed in the FACTs project, the authors being of the opinion that they match quite well. The measurements indicate that exponential profiles for wind speed cannot be used in complex terrain. The results of the comparison between heated and non-heated anemometers show that the FACTs model predicts icing risks quite well.

  12. Development of buried wire gages for measurement of wall shear stress in Blastane experiments

    Science.gov (United States)

    Murthy, S. V.; Steinle, F. W.

    1986-01-01

    Buried Wire Gages operated from a Constant Temperature Anemometer System are among the special types of instrumentation to be used in the Boundary Layer Apparatus for Subsonic and Transonic flow Affected by Noise Environment (BLASTANE). These Gages are of a new type and need to be adapted for specific applications. Methods were developed to fabricate Gage inserts and mount those in the BLASTANE Instrumentation Plugs. A large number of Gages were prepared and operated from a Constant Temperature Anemometer System to derive some of the calibration constants for application to fluid-flow wall shear-stress measurements. The final stage of the calibration was defined, but could not be accomplished because of non-availability of a suitable flow simulating apparatus. This report provides a description of the Buried Wire Gage technique, an explanation of the method evolved for making proper Gages and the calibration constants, namely Temperature Coefficient of Resistance and Conduction Loss Factor.

  13. Remote sensing used for power curves

    Science.gov (United States)

    Wagner, R.; Jørgensen, H. E.; Paulsen, U. S.; Larsen, T. J.; Antoniou, I.; Thesbjerg, L.

    2008-05-01

    : Power curve measurement for large wind turbines requires taking into account more parameters than only the wind speed at hub height. Based on results from aerodynamic simulations, an equivalent wind speed taking the wind shear into account was defined and found to reduce the power standard deviation in the power curve significantly. Two LiDARs and a SoDAR are used to measure the wind profile in front of a wind turbine. These profiles are used to calculate the equivalent wind speed. The comparison of the power curves obtained with the three instruments to the traditional power curve, obtained using a cup anemometer measurement, confirms the results obtained from the simulations. Using LiDAR profiles reduces the error in power curve measurement, when these are used as relative instrument together with a cup anemometer. Results from the SoDAR do not show such promising results, probably because of noisy measurements resulting in distorted profiles.

  14. SUBMERGED IMPINGING JETS WITHIN A FINITE WATER DEPTH

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    By use of the sheet of laser light and the trac-ing particle technology, flow visualization tests of complexflow structures for submerged impinging jets within finite wa-ter depths are conducted. Typical flow patterns of submergeimpinging jets are analysed by the singular topology method.In order to reveal the mechanism of these flows, the diffusivecharacteristics and turbulent fluctuations of submerged impin-ging jets are measured by the hot-film anemometer.

  15. Hydrography and circulation off the west coast of India during the southwest monsoon 1987

    Digital Repository Service at National Institute of Oceanography (India)

    Shetye, S.R.; Gouveia, A.D.; Shenoi, S.S.C.; Sundar, D.; Michael, G.S.; Almeida, A.M.; Santanam, K.

    .7.1987 10.7.1987 I 05.8.1 987 08.8.1987 J 01.8.1987 04.8.1987 K 28.7.1987 01.8.1987 L 23.7.1987 27.7.1987 M 19.7.1987 22.7.1987 364 Journal ofMarine Research (48, 2 once every three hours using a ship-based anemometer, and were corrected for the movement...

  16. Properties of velocity field in the vicinity of synthetic jet generator

    Science.gov (United States)

    Strzelczyk, P.; Gil, P.

    2016-10-01

    The paper presents the results of experimental investigation of velocity field in the vicinity of synthetic jet actuator as a function of Stokes number and for constant Reynolds number. A constant temperature hot-wire anemometer with tungsten-platinum coated single wire probe used for the velocity measurements. Synthetic jet flow visualization was presented, especially process of vortex ring development. Synthetic jet velocity profiles were compared with a solution to fully-developed pipe flow with an oscillating pressure gradient.

  17. Tall Tower Wind Energy Monitoring and Numerical Model Validation in Northern Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Koracin, D. [Desert Research Inst. (DRI), Las Vegas, NV (United States); Kaplan, M. [Desert Research Inst. (DRI), Las Vegas, NV (United States); Smith, C. [Desert Research Inst. (DRI), Las Vegas, NV (United States); McCurdy, G. [Desert Research Inst. (DRI), Las Vegas, NV (United States); Wolf, A. [Desert Research Inst. (DRI), Las Vegas, NV (United States); McCord, T. [Desert Research Inst. (DRI), Las Vegas, NV (United States); King, K. [Desert Research Inst. (DRI), Las Vegas, NV (United States); Belu, R. [Drexel Univ., Philadelphia, PA (United States); Horvath, K. [Croatian Meteorological and Hydrological Service, Zagreb (Croatia)

    2015-10-01

    The main objectives of this project were to conduct a tall-tower and sodar field campaign in complex terrain, investigate wind properties relevant to wind energy assessment, and evaluate high-resolution models with fixed and adaptive grid structures. Two 60-m towers at Virginia Peak ridges near Washoe Valley, Nevada, were instrumented with cup and vane anemometers as well as sonic anemometers, and an acoustic sounder (hereafter sodar) was installed near one of the towers. The towers were located 2,700 m apart with a vertical distance of 140 m elevation between their bases. Each tower had a downhill exposure of rolling complex terrain, with the nearby valley floor 3,200 m to the west and 800 m below the summit. Cup anemometers were installed at both towers at 20, 40, and 60 m, wind vanes at 20 and 60 m, and sonic anemometers at 20 and 60 m. The sodar measurements were nominally provided every 10 m in vertical distance from 40 to 200 m with the quality of the data generally decreasing with height. Surface air temperature, atmospheric pressure, and radiation measurements were conducted at 1.5 m AGL at both of the towers. Although the plan was to conduct a 1-year period of data collection, we extended the period (October 5, 2012 through February 24, 2014) to cover for possible data loss from instrument or communication problems. We also present a preliminary analysis of the towers and sodar data, including a detailed inventory of available and missing data as well as outliers. The analysis additionally includes calculation of the Weibull parameters, turbulence intensity, and initial computation of wind power density at various heights.

  18. СИСТЕМА АВТОМАТИЗИРОВАННОГО КОНТРОЛЯ И ПРОГНОЗИРОВАНИЯ ОСТОЙЧИВОСТИ МАЛОМЕРНОГО СУДНА

    Directory of Open Access Journals (Sweden)

    ТИМЧЕНКО Виктор Леонидович

    2014-05-01

    Full Text Available Based multifunctional anemometer system, block modeling of sea waves and a system of sensors (inclinometers developed an automated system that allows to forecast parameters of rolling small vessel on a given interval of pre-emption, whereby the skipper receives information on the projected values of the roll angles, which will reduce the level of accidents operating small vessels in adverse weather conditions.

  19. Generating Variable Wind Profiles and Modeling Their Effects on Small-Arms Trajectories

    Science.gov (United States)

    2016-04-01

    References 19 Appendix A. Synthesis of McCoy and Weinacht- Cooper -Newill Methodologies 21 Appendix B. Supplementary Monte Carlo Results 23 Appendix C...methodology alongside the Weinacht- Cooper -Newill (WCN) projectile flyout methodology to obtain measures of ECC. Section 4 will briefly summarize...wind perpendicular to the line connecting the anemometers, with positive crosswind values to the right as you look from A1 to A10, and range wind is

  20. Measurement of Turbulence Energy Balance in a Two-Dimensional Wall Jet along a Plane Surface

    OpenAIRE

    藤沢, 延行; 白井, 紘行

    1987-01-01

    The sructure of turbulence in a wall jet along a plane surface is investigated by measuring the balance of turbulence energy. With the aid of a hot-wire anemometer system, convection velocities of small-scale turbulent motion are measured as well as other time-averaged flow properties and turbulence characteristics. It is found that the convection velocity of small-scale turbulence deviates significantly from the mean flow velocity, that is, Taylor's hypothesis is not valid for the present wa...

  1. Onshore Wind Stress and Buoyancy Flux Observed on a Dissipative Mediterranean Beach

    Science.gov (United States)

    2015-12-01

    and terrestrial radiation. On April 11, 2015, a second sonic anemometer was added at a height of 3m. All sensors were wired to a Campbell Scientific...from mixing upward while under unstable conditions when thermal instability and convection work to enhance turbulent mixing. Studies have... convective sublayer, 1.20  z / L  0.12 , describes conditions where thermal instabilities become significant but do not yet dominate mechanical

  2. A Study of A Flow through Small Apertures(2nd Report, Experiments on The Velocity Field)

    OpenAIRE

    福冨, 清; 長谷川, 富市; 中野, 裕二; 鳴海, 敬倫; Hasegawa, Tomiichi; Narumi, Takatsune

    1987-01-01

    The velocity field of an inlet and outlet flow through small orifices was experimentally examined. The velocity along the center line near the orifices was measured with a laser doppler anemometer, stream lines in the whole flow region were photographed, and the following points were clarified : (1) The center line velocities of liquid paraffin agree with the theoretical value of Stokes flow in the region of Reynolds numbers below 10. (2) With distilled water, a diverging angle of the issuing...

  3. REMOTE RECORDING ANNULAR VANE ASSEMBLY

    Science.gov (United States)

    Wehmann, G.

    1963-06-25

    A weather vane apparatus is described which is capable of movement in horizontal and vertical planes. Associated with the vane are tangent potentiometers, commutators, and other electrical apparatus for deriving electrical output voltages as a function of the wind direction. The apparatus is particularly adapted for use with an anemometer to provide an electrical output indicating the amount and direction of an up or down draft. (AEC)

  4. A comparison of calibration techniques for hot-wires operated in subsonic compressible slip flows

    Science.gov (United States)

    Jones, Gregory S.; Stainback, P. C.; Nagabushana, K. A.

    1992-01-01

    This paper focuses on the correlation of constant temperature anemometer voltages to velocity, density, and total temperature in the transonic slip flow regime. Three different calibration schemes were evaluated. The ultimate use of these hot-wire calibrations is to obtain fluctuations in the flow variables. Without the appropriate mean flow sensitivities of the heated wire, the measurements of these fluctuations cannot be accurately determined.

  5. Further Studies Of Hot-Wire Anemometry

    Science.gov (United States)

    Mckenzie, Robert; Logan, Pamela; Bershader, Daniel

    1990-01-01

    Report discusses factors affecting readings of hot-wire anemometer in turbulent supersonic boundary layer. Represents extension of work described in "Hot-Wire Anemometry Versus Laser-Induced Fluorescence" (ARC-11802). Presents theoretical analysis of responses of hot-wire probe to changes in flow; also compares measurements by hot-wire probe with measurements of same flows by laser-induced fluorescence (LIF).

  6. Capture of instantaneous temperature in oscillating flows: use of constant-voltage anemometry to correct the thermal lag of cold wires operated by constant-current anemometry.

    Science.gov (United States)

    Berson, Arganthaël; Poignand, Gaëlle; Blanc-Benon, Philippe; Comte-Bellot, Geneviève

    2010-01-01

    A new procedure for the instantaneous correction of the thermal inertia of cold wires operated by a constant-current anemometer is proposed for oscillating flows. The thermal inertia of cold wires depends both on the wire properties and on the instantaneous incident flow velocity. Its correction is challenging in oscillating flows because no relationship between flow velocity and heat transfer around the wire is available near flow reversal. The present correction procedure requires neither calibration data for velocity nor thermophysical or geometrical properties of the wires. The method relies on the splitting of the time lag of cold wires into two factors, which are obtained using a constant-voltage anemometer in the heated mode. The first factor, which is intrinsic to the wire, is deduced from time-constant measurements performed in a low-turbulence flow. The second factor, which depends on the instantaneous flow velocity, is acquired in situ. In oscillating flows, data acquisition can be synchronized with a reference signal so that the same wire is alternatively operated in the cold mode by a constant-current anemometer and in the heated mode by a constant-voltage anemometer. Validation experiments are conducted in an acoustic standing-wave resonator, for which the fluctuating temperature field along the resonator axis is known independently from acoustic pressure measurements, so that comparisons can be made with cold-wire measurements. It is shown that despite the fact that the wire experiences flow reversal, the new procedure recovers accurately the instantaneous temperature of the flow.

  7. A strategy to eliminate all nonlinear effects in constant-voltage hot-wire anemometry

    Science.gov (United States)

    Berson, Arganthaël; Blanc-Benon, Philippe; Comte-Bellot, Geneviève

    2009-04-01

    A constant-voltage anemometer is subject to nonlinear effects when the operating hot wire is exposed to large velocity fluctuations in the incident flow. This results in the generation of undesirable higher harmonics, just as in the two classic systems, constant-current and constant-temperature anemometers, for which no attempts are normally made to correct the nonlinearities. The present investigation shows that these undesirable higher harmonics can be suppressed in the case of a constant-voltage anemometer. A new approach to process experimental data is proposed. It is based on three explicit equations established and solved with all terms included, i.e., without linearization. These are (1) the first-order differential equation that describes the electronic circuit of a constant-voltage anemometer—this equation permits to deduce the instantaneous resistance of the hot wire from the output voltage of the anemometer; (2) the first-order differential equation that expresses the thermal lag behavior of the hot wire when used in a constant-voltage mode—this equation permits to restore the instantaneous resistance that an ideal wire would have without thermal inertia in the same flow conditions; and (3) the algebraic relation that expresses the heat-transfer law of an ideal wire, according to King's law, a look-up table, or a polynomial fit—this relation permits to deduce the instantaneous flow velocity from the instantaneous resistance of the ideal wire. The proposed method is easily implemented on a personal computer and permits odd turbulence moments, such as skewness factors, to be obtained satisfactorily.

  8. Project Themis Supercritical Cold Flow Facility, Experiment Design and Modeling for the Study of Fluid Mixing

    Science.gov (United States)

    2012-06-01

    capture the mean flow field temperatures. Figure 10. Hot - wire Anemometry Probes Baselined for Instrumentation Rake 12 American Institute of...instrumentation as seen in Figure 8. The hollow stinger houses the hot - wire probe cabling. The rake stinger passes through a Swagelok sealed port on a...pressure transducers, thermocouples, and an instrumentation rake of hot - wire anemometer sensors. The layout of the externally 11 American Institute

  9. Measurements and Modeling of the Mean and Turbulent Flow Structure in High-Speed Rough-Wall Non-Equilibrium Boundary Layers

    Science.gov (United States)

    2010-01-25

    transverse velocity and density fluctuations ( /v uρ ρ′ ′ ), directly measured by combining the response from hot - wire anemometry with laser Doppler...R., “Combined Laser Doppler Velocimetry and Cross- Wire Anemometry Analysis for Supersonic Turbulent Flow,” AIAA Journal, Vol. 34, 1996, pp. 2269...Mechanics Reviews, Vol. 44, Jan. 1991, pp. 1-25. Robinson, S., Seegmiller, H., and Kussoy, M., “ Hot - Wire and Laser Doppler Anemometer Measurements

  10. Unsteady Aerodynamics for Micro Air Vehicles (Aerodynamique instable pour micro-vehicules aeriens)

    Science.gov (United States)

    2010-09-01

    section. The measured velocity variations in the core flow are below 1%. The turbulence level was measured by means of the hot wire anemometry . The...level (>3%). So the results presented here are only obtained in towing- tank mode. Tests with hot wires in the water show that the residual...free- stream velocity was controlled via closed-loop control, with the tunnel speed input obtained from a hot - wire anemometer (Dantec Dynamics A/S

  11. Induced airflow in flying insects II. Measurement of induced flow.

    Science.gov (United States)

    Sane, Sanjay P; Jacobson, Nathaniel P

    2006-01-01

    The flapping wings of insects and birds induce a strong flow over their body during flight. Although this flow influences the sensory biology and physiology of a flying animal, there are very little data on the characteristics of this self-generated flow field or its biological consequences. A model proposed in the companion paper estimated the induced flow over flying insects. In this study, we used a pair of hot wire anemometers to measure this flow at two locations near the body of a tethered flapping hawk moth, Manduca sexta. The axial inflow anemometer measured the airflow prior to its entry into the stroke plane, whereas the radial outflow anemometer measured the airflow after it crossed the stroke plane. The high temporal resolution of the hot wire anemometers allowed us to measure not only the mean induced flow but also subtle higher frequency disturbances occurring at 1-4 times the wing beat frequency. These data provide evidence for the predictions of a mathematical model proposed in the companion paper. Specifically, the absolute value of the measured induced flow matches the estimate of the model. Also, as predicted by the model, the induced flow varies linearly with wing beat frequency. Our experiments also show that wing flexion contributes significantly to the observed higher frequency disturbances. Thus, the hot wire anemometry technique provides a useful means to quantify the aerodynamic signature of wing flexion. The phasic and tonic components of induced flow influence several physiological processes such as convective heat loss and gas exchange in endothermic insects, as well as alter the nature of mechanosensory and olfactory stimuli to the sensory organs of a flying insect.

  12. Uncertainties in surface mass and energy flux estimates due to different eddy covariance sensors and technical set-up

    Science.gov (United States)

    Arriga, Nicola; Fratini, Gerardo; Forgione, Antonio; Tomassucci, Michele; Papale, Dario

    2010-05-01

    Eddy covariance is a well established and widely used methodology for the measurement of turbulent fluxes of mass and energy in the atmospheric boundary layer, in particular to estimate CO2/H2O and heat exchange above ecologically relevant surfaces (Aubinet 2000, Baldocchi 2003). Despite its long term application and theoretical studies, many issues are still open about the effect of different experimental set-up on final flux estimates. Open issues are the evaluation of the performances of different kind of sensors (e.g. open path vs closed path infra-red gas analysers, vertical vs horizontal mounting ultrasonic anemometers), the quantification of the impact of corresponding physical corrections to be applied to get robust flux estimates taking in account all processes concurring to the measurement (e.g. the so-called WPL term, signal attenuation due to air sampling system for closed path analyser, relative position of analyser and anemometer) and the differences between several data transmission protocols used (analogue, digital RS-232, SDM). A field experiment was designed to study these issues using several instruments among those most used within the Fluxnet community and to compare their performances under conditions supposed to be critical: rainy and cold weather conditions for open-path analysers (Burba 2008), water transport and absorption at high air relative humidity conditions for closed-path systems (Ibrom, 2007), frequency sampling limits and recorded data robustness due to different transmission protocols (RS232, SDM, USB, Ethernet) and finally the effect of the displacement between anemometer and analyser using at least two identical analysers placed at different horizontal and vertical distances from the anemometer. Aim of this experiment is to quantify the effect of several technical solutions on the final estimates of fluxes measured at a point in the space and if they represent a significant source of uncertainty for mass and energy cycle

  13. Turbulence Measurements in Swirling Flows

    Directory of Open Access Journals (Sweden)

    V. M. Domkundwar

    1981-10-01

    Full Text Available Investigation have been conducted to find out the region of high turbulent intensities in a swirling jet passing through a divergent passage. A hot wire anemometer is used to measure the turbulence intensity using a four position method. It has been concluded that the jet spreads with increasing diffuser angle and the region of high turbulent intensity also spreads. The high turbulence intensity region lies around the recirculation zone and it decays rapidly along the main flow direction.

  14. Accuracy limitations for low velocity measurements and draft assessment in rooms

    DEFF Research Database (Denmark)

    Melikov, Arsen Krikor; Popiolek, Zbigniew J.; Silva, M.G.

    2007-01-01

    must be known in order to perform reliable assessment and validation. At present, a low-velocity thermal anemometer (LVTA) with an omnidirectional (spherical) sensor is most often used in practice for measuring air speed due to its low price and easy and convenient operation. The accuracy of the speed......, the definition of realistic requirements in thermal comfort standards as well as validation of CFD predictions is made possible....

  15. A 10-gram Microflyer for Vision-based Indoor Navigation

    OpenAIRE

    Zufferey, Jean-Christophe; Klaptocz, Adam; Beyeler, Antoine; Nicoud, Jean-Daniel; Floreano, Dario

    2006-01-01

    We aim at developing ultralight autonomous microflyers capable of navigating within houses or small built environments. Our latest prototype is a fixed-wing aircraft weighing a mere 10 g, flying around 1.5 m/s and carrying the necessary electronics for airspeed regulation and collision avoidance. This microflyer is equipped with two tiny camera modules, two rate gyroscopes, an anemometer, a small microcontroller, and a Bluetooth radio module. In-flight tests are carried out ...

  16. A 10-gram Vision-based Flying Robot

    OpenAIRE

    Zufferey, Jean-Christophe; Klaptocz, Adam; Beyeler, Antoine; Nicoud, Jean-Daniel; Floreano, Dario

    2007-01-01

    We aim at developing ultralight autonomous microflyers capable of freely flying within houses or small built environments while avoiding collisions. Our latest prototype is a fixed-wing aircraft weighing a mere 10 g, flying around 1.5 m/s and carrying the necessary electronics for airspeed regulation and lateral collision avoidance. This microflyer is equipped with two tiny camera modules, two rate gyroscopes, an anemometer, a small microcontroller, and a Bluetooth rad...

  17. On the Analytical Approach to Present Engineering Problems: Photovoltaic Systems Behavior, Wind Speed Sensors Performance, and High-Speed Train Pressure Wave Effects in Tunnels

    Directory of Open Access Journals (Sweden)

    Santiago Pindado

    2015-01-01

    Full Text Available At present, engineering problems required quite a sophisticated calculation means. However, analytical models still can prove to be a useful tool for engineers and scientists when dealing with complex physical phenomena. The mathematical models developed to analyze three different engineering problems: photovoltaic devices analysis; cup anemometer performance; and high-speed train pressure wave effects in tunnels are described. In all cases, the results are quite accurate when compared to testing measurements.

  18. Measurement and modeling of bed shear stress under solitary waves

    Digital Repository Service at National Institute of Oceanography (India)

    Jayakumar, S.; Guard, P.A.; Baldock, T.E.

    in the boundary Author version: Coast. Eng., vol.58(9); 2011; 937-947 3 layer, * u , ( ρτ / * =u ) can be obtained from a logarithmic profile fit to the velocity profile measured using different techniques and instrumentation. These methods include Laser... Doppler Anemometers (LDA) (Compton and Eaton, 1996; Lim and Lewkowicz, 1986), Particle Image Velocimetry (PIV) (e.g., Jensen et al., 1989; Liu et al., 2007), Laser Doppler Velocimeter (LDV) (e.g., Skjelbreia, 1987). These methods are nonintrusive...

  19. Qualitative comparison of concurrent vertical optical turbulence profiles from an aircraft and balloons over White Sands Missile Range

    Science.gov (United States)

    Nowlin, Scott R.; Hahn, Ila L.; Hugo, Ronald J.; Bishop, Kenneth P.

    1999-08-01

    We report simultaneous balloon-borne thermosonde/airborne constant-current anemometer measurements made over a portion of White Sands Missile Range, NM. For the first time, vertical profiles of the refractive index structure parameter (Cn2) data generated from shallow slant aircraft flight paths are compared to the balloons vertical Cn2 distributions. We discuss possible adverse effects of meteorology and atmospheric velocity fluctuations. We present conclusions and make recommendations for future similar experimental efforts.

  20. Time series analysis of continuous-wave coherent Doppler Lidar wind measurements

    DEFF Research Database (Denmark)

    Sjöholm, Mikael; Mikkelsen, Torben; Mann, Jakob;

    2008-01-01

    The influence of spatial volume averaging of a focused 1.55 mu m continuous-wave coherent Doppler Lidar on observed wind turbulence measured in the atmospheric surface layer over homogeneous terrain is described and analysed. Comparison of Lidar-measured turbulent spectra with spectra...... simultaneously obtained from a mast-mounted sonic anemometer at 78 meters height at the test station for large wind turbines at Hovsore in Western Jutland, Denmark is presented for the first time....