![]() ![]() horizontal wind speed component measured with the spinner anemometer and corrected with the nacelle transfer function to free wind speed.horizontal wind speed component (free wind speed measured with the met-mast).rotor induction, calculated as I = ( U m m− U h o r)/ U m m.calibration correction factor mainly related to angle calibration (equal to F α.calibration correction factor related to angle calibration.calibration correction factor mainly related to wind speed calibration.calibration constant mainly related to angle calibration (equal to k α.calibration constant related to angle calibration.calibration constant mainly related to wind speed calibration.wind direction referred to geographical coordinate system.yaw direction referred to geographical coordinate system.azimuth position of flow stagnation point on spinner (relative to sonic sensor 1).rotor position (equal to zero when sonic sensor one is at top position, positive clockwise).inflow angle with respect to the shaft axis measured by the spinner anemometer prior to calibration.inflow angle with respect to the shaft axis.flow inclination angle (positive when upwards).vertical wind velocity component, along z n.wind velocity component in the plane perpendicular to the shaft axis x s.horizontal wind speed component measured with the spinner anemometer (corrected with F α but not F 1).horizontal wind speed component measured with the spinner anemometer (non-calibrated value).horizontal wind speed component measured with the spinner anemometer (calibrated value).wind speed vector modulus at the spinner anemometer (reference value to calibrate U d, equal to the free wind speed vector modulus in stopped conditions or conditions of null rotor induction).wind speed vector modulus measured by the spinner anemometer prior to calibration.velocity component of the wind speed along sensor path 3.velocity component of the wind speed along sensor path 2.velocity component of the wind speed along sensor path 1.Copyright © 2016 The Authors Wind Energy Published by John Wiley & Sons Ltd. The evaluation of uncertainty was not included in the present analysis. The method that entails stopping the turbine in good wind conditions showed the best results and is recommended. Two alternative methods that did not require the turbine to be stopped were investigated: one used relatively high wind speed measurements during normal operation of the wind turbine, while the other one used a CFD simulation of the flow over the spinner. The first and preferred method is based on the definition of the calibration constant and uses wind speed measurements during the stopped condition of the wind turbine. The present analysis describes methods to determine the calibration constant related to wind speed measurements. The algorithm utilizes two calibration constants that are specific to the spinner shape, blade root design and to the mounting positions of the sonic sensors on the 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 wind speed, yaw misalignment and flow inclination angle. The measurement principle of the spinner anemometer is based on the flow distortion caused by the wind turbine spinner. Another option is to use a spinner anemometer. Typically, a sonic anemometer or a cup anemometer and a wind vane are mounted on the back of the nacelle roof. These are better in higher air speed applications such as environmental monitoring as they cannot read very low air speeds, but are fine for use at higher speeds.The power curve of a wind turbine can be measured, according to IEC 6 with a nacelle-mounted anemometer. This is different to a vane anemometer which operates like a windmill – the air flow turns the vanes on the propellor, which is related back to air speed. ![]() The sensor of the anemometer has a fine wire which is heated to above the ambient temperature.Īny air flow over the wire then cools it slightly – this cooling changes the resistance of the wire, which is related back to the air flow speed or velocity. Some applications may be measuring relatively slow or low velocity air flow – which anemometer is best to accurately measure these? Measuring low velocity air flow needs an anemometer sensitive at lower ranges – a hot wire anemometer should be selectedįor low air flow or low velocity applications, a hot wire anemometer should be selected as these are more sensitive at lower air flow rates. Anemometers are used to measure air flow in environmental studies or site monitoring. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |