• Title, Summary, Keyword: Anemometer

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Sensitivity Enhancement of a Hot-Wire Anemometer by Changing Overheat Ratio with Velocity (유속에 따른 열선의 과열비 조정을 통한 열선유속계의 감도향상에 관한 연구)

  • ;;Kauh, S. K.
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.10
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    • pp.2678-2689
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    • 1995
  • In this study, a new hot-wire anemometer which has greater sensitivity than that of a constant temperature anemometer (CTA) was proposed. In contrast to CTA, the wire working resistance of the new anemometer increases with flow velocity, that is, the operating mode of the wire becomes variable temperature. The variable temperature anemometer(VTA) was made by substituting a voltage controlled variable resistor such as photoconductive cell or transistor for one of the resistors in the bridge. By positively feeding back the bridge top signal to the input side of these electronic components, the wire overheat ratio could be increased with velocity automatically. Static response analyses of the VTA, constant voltage anemometer (CVA) and CTA were made in detail and calibration experiments were performed to validate the proposed operating principle. The wire operating resistance of the CVA decreases with velocity and this leads to lower sensitivity than that of a CTA. But the sensitivity of the newly proposed VTA is superior to that of a CTA, since the wire overheat ratio increases with velocity. Consequently, it is found that the major factor that is responsible for large sensitivity of a VTA is not the working resistance itself but the change of the wire working resistance with velocity.

Verification of Wind Sensor Position (풍향.풍속계의 위치 적합성 판단)

  • Jeong, Wang-Jo
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • pp.171-172
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    • 2006
  • The anemometer on the radar mast of the vessel is equipped to measure wind direction and speed. This project was carried out to verify the position of anemometer which makes anemometer measure exact wind direction and speed. FLUENT was used to perform this analysis.

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Technique for Measuring Wind Speed and Direction Using a Roll-rotating Three-Axis Ultrasonic Anemometer (롤 회전하는 3축 초음파 풍속계를 활용한 풍향 풍속 측정기법)

  • Chang, Byeong Hee;Lee, Seunghoon;Cho, Tae Hwan;Kim, Yang won
    • Journal of Wind Energy
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    • v.9 no.3
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    • pp.5-12
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    • 2018
  • A technique for measuring wind speed and direction by using a roll-rotating three-axis ultrasonic anemometer was proposed and verified by wind tunnel tests. The test conditions were chosen to cover the operational range of typical wind turbines. The results of measuring the roll-rotating three-axis ultrasonic anemometer were converted on a fixed-roll axis and compared with those of a non-rotating anemometer. As a result, the residual errors that remained after axis transform were within the anemometer accuracy except for an RMS error of wind speed at yaw $30^{\circ}C$. But at yaw $0^{\circ}C$, it was reduced within the anemometer accuracy. This roll-rotating measuring technique was successful regardless of rotating speed, wind speed, and sampling rate. In order to use this rotating measuring technique as a spinner anemometer for wind turbines, the effect of the spinner has to be considered Theoretically, the effect of the spinner amplifies the wind direction along the rotational axis and the measured flow direction is larger than the incoming wind direction. This trend seems to be favorable for yaw control if wind direction is measured during yaw motion and feedback to yaw control.

Structural Design and Analysis for 3D Ultrasonic Anemometer

  • Kim, Kyung-Won;Choi, Jae-Yeong;Lee, Woo-Jin;Lee, Seon-Gil
    • Journal of Sensor Science and Technology
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    • v.25 no.2
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    • pp.86-90
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    • 2016
  • A 3D ultrasonic anemometer measures the direction and velocity of wind in a 3D space. The 2D ultrasonic anemometers developed by different manufacturers do not differ significantly in terms of their form or structure. The 3D ultrasonic anemometers, on the other hand, have more diverse forms than their 2D counterparts depending on the measurement algorithms and methods. Designing and reviewing the structure at the initial stage and defining its performance objectives are time-consuming processes. The process can be made cost-effective and time-saving if the validity is tested by model design and structural interpretation, and the structure is designed to withstand high wind velocities. This study presents the results of a 3D ultrasonic anemometer on real sample data by using a 3D modeling program, CATIA, for ultrasonic anemometer modeling.

Technique of Measuring Wind Speed and Direction by Using a Roll-rotating Three-Axis Ultrasonic Anemometer (II) (롤 회전하는 3축 초음파 풍속계를 활용한 풍향 풍속 측정기법(II))

  • Chang, Byeong Hee;Lee, Seunghoon;Kim, Yang won
    • Journal of Wind Energy
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    • v.9 no.4
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    • pp.9-15
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    • 2018
  • In a previous study, a technique for measuring wind speed and direction by using a roll-rotating three-axis ultrasonic anemometer was proposed and verified by wind tunnel tests. In the tests, instead of a roll sensor, roll angle was trimmed to make no up flow in the transformed wind speeds. Verification was done in point of the residual error of the rotation effect treatment. In this study, roll angle was measured from the roll motor encoder and the transformed wind speed and direction on the test section axis were compared with the ones provided to the test section. As a result, up to yaw $20^{\circ}$ at a wind speed of 12 m/sec or over, the RMS error of wind speed was within the double of the ultrasonic anemometer error. But at yaw $30^{\circ}$, it was over the double of the ultrasonic anemometer error. Regardless of wind speed, at yaw $20^{\circ}$ and $30^{\circ}$, the direction error was within the double of the ultrasonic anemometer error. But at yaw $10^{\circ}$ or less, it was within the error of the ultrasonic anemometer itself. This is a very favorable characteristic to be used for wind turbine yaw control.

Development of 3 - Dimensional Ultrasonic Wind Direction Anemometer Measurement Technique Using Time Division Method (시분할 방식을 이용한 3차원 초음파 풍향풍속계 측정기술 개발)

  • Lee, Woo-Jin;Choi, Jae-Young;Kim, Kyung-Won;Yim, Jae-Hong
    • Journal of Sensor Science and Technology
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    • v.26 no.1
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    • pp.66-72
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    • 2017
  • The three dimensional ultrasonic anemometer was constructed to reduce the disadvantages of the two-dimensional anemometer and to be free from the use environment. Three pairs of transmitting and receiving ultrasonic sensors were designed to face each other at an angle of $45^{\circ}$ to the upper and lower surfaces at intervals of $120^{\circ}$. 200 kHz ultrasonic sensor Oscillation, transmission and reception, level detection, power supply circuit were designed and U, V, W wind speed vector components were obtained by measuring the time of first received ultrasonic pulse by transmitting pulse ultrasound. It is implemented as firmware in ARM Coretex-M3 processor so that horizontal and vertical wind direction and wind speed can be converted into digital signal by vector calculation. In this study, The three-dimensional ultrasonic anemometer can complement the disadvantages of the two-dimensional anemometer (mechanical and ultrasonic), and it is expected to gradually replace the two-dimensional anemometer due to its high utilization rate by collecting additional information such as vertical wind.

The Correction of Fluid Temperature for Hot-wire Anemometer (열선 유속계에 대한 유체 온도의 보정)

  • 심상학
    • Journal of The Korean Society of Manufacturing Technology Engineers
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    • v.8 no.6
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    • pp.92-97
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    • 1999
  • This paper reports by simple method that is quickly corrected the effects of fluid temperature for the hot wire anemometer. We are concerned with a variable output of hot wire anemometer on arbitrary fluid temperature. Hot wire by measuring boundary layer of turbulent flow has been calibrated by arbitrary temperature lower than 10$0^{\circ}C$, and velocity lower than 20m/s. As a result, we could pick up the temperature factor affected by output of hot wire anemometer from related in output of arbitrary temperature to output of room temperature. By using temperature factor on the output of hot wire anemometer, we also obtained that the relationship of velocity was of no effect by temperature of fluids. About results of calibrated hot wire, uncertainly of velocity is 2.15% at room temperature and 3.1% at arbitrary temperature.

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The Study of Performance Improvement of the 3-Cup Anemometer using Interpolation Methods (Interpolation을 이용한 3-CUP Anemometer의 성능 개선에 관한 연구)

  • 이성신;정택식;구법모
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.672-675
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    • 2001
  • In this paper, we propose that the calculation method for accurate wind speed using interpolation methods, and the finding method for accurate wind direction using interpolation polynomial, so we make better performance for 3-Cup Anemometer by the proposed methods. We embody the 3-Cup Anemometer with photo sensor to measure wind direction and wind speed. In order to more accurate wind speed and wind direction, we present the methods to overcome the limitations of system memory and of the sensor measurement error by 8 bit gray code (as substitute 360 degrees for 256 degrees data).

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Calibration Equation for Nacelle Anemometer Derived by LIDAR Measurements (라이다 측정을 이용한 나셀 풍속계 보정식 제안)

  • Kim, Hyun-Goo;An, Hae-Joon;Yang, Seung-Joo;Park, Woo-Jae;Kim, Seok-Woo
    • New & Renewable Energy
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    • v.9 no.1
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    • pp.12-16
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    • 2013
  • The nacelle anemometer mounted behind the blade roots of a wind turbine measures distorted wind speed comparable with free-stream wind because of the wake effects caused dependent upon the operation of the wind turbine and the rotation of its blades. The field campaign was carried out to measure free-stream wind speed at a height identical to the height of the nacelle anemometer by deploying a ground-based remote-sensing equipment, LIDAR. It is derived that a third-order polynomial equation for correcting wind speed measured by the nacelle anemometer to undistorted free-stream wind speed incident to a wind turbine. It is anticipated that the derived correction equation enables wind speed measured by the nacelle anemometer to be used as a precise input for a wind turbine performance test and for developing an active control logic.