Sirnegeda Techane , Atlanta Metropolitan College Introduction COLUMN NAME:ABSOLUTE WIND COLUMN NAME:ABSOLUTE There are several sensors for measuring DIFFERENCE WIND SPEED DIFFERENCE wind speed and direction. The most Number of rows: 768 Number of rows: 768 common are anemometers and wind vanes Number of valid points: 768 Number of valid points: 768 which are used at airports, on most ships, C) Wind Monitor –AQ model 05305 and at weather stations. An anemometer The wind monitor is a four-blade Number of missing points: 0 Number of missing points: 0 A) Type 40 Maximum B) 200 Series Wind Vane helicoid propeller. Propeller rotation Number of negative values: 0 Number of negative values: 0 measures wind speed and a wind vane Anemometer The 200 series Wind Direction measures wind direction. The vane rotates, This sensor records wind produces an AC sine voltage. This Number of positive values: 768 Number of positive values: 768 Vane has thermoplastic and AC signal is induced in a stationary seeking equilibrium, which occurs when it speeds to 96 m/s (214 mph). It stainless steel components that Number of zero values: 0 Number of zero values: 0 has three conical cups are coil by a six-pole magnet mounted on is pointing directly into the wind. Typically, resist corrosion, and contribute to the propeller shaft. Three complete Minimum value: 18.7 Minimum value: 0.001 molded in one continuous piece the anemometer and wind vane are mounted a high strength-to-weight sine wave cycles are produced from Maximum value: 221.0 Maximum value: 1.773 and are mounted 120o apart. Cup on opposite ends of a cross member which, rotation. The vane is directly each propeller revolution, which Inter range value: 202.3 Inter range value: 1.772 rotation induces a sine wave connected to a precision represents 9.8 cm of wind passage. in turn, attaches to an upright pole. An voltage in a single coil by a four- Median: 178.1 Median: 0.318 conductive plastic potentiometer Vane position is transmitted by a anemometer usually consists of three pole magnet. Two sine wave located in the main body. An Sum of row value: 132899.8 Sum of row value: 284.5 cycles are produced for each 10K ohm precision conductive plastic aerodynamically shaped cups mounted 120o analog output directly potentiometer, which requires a Sum of absolute value: 132899.8 Sum of absolute value: 284.5 apart. rotation of the cups with the proportional to the wind regulated excitation voltage. With a Arithmetric mean: 173.05 Arithmetric mean: 0.370 frequency directly proportional direction is produced when a known voltage applied to the Quadratic mean: 174.7 Quadratic mean: 0.472 to wind speed. Because of their constant DC excitation voltage is potentiometer, the output signal is an output linearity, these sensors are Harmonic mean: 163.5 Harmonic mean: 0.076 applied to the potentiometer. analog voltage directly proportional ideal for use with various data Absolute mean: 173.05 Absolute mean: 0.370 retrieval systems and to azimuth angle. controllers. Actual Wind Direction vs. Julian day 350 Wind direction vs. Julian day 300 300 wind direction (degrees) Purpose Wind direction (degrees) 250 250 200 The purpose of the project was to compare the data 150 200 Comparing the sensors collected for horizontal wind speed and direction from 100 150 Horizontal wind speed sensors The horizontal wind speed data collected from the wind Monitor and from the the National Oceanic and Atmospheric Administration 50 100 Cup Anemometer have almost similar values. Since we used the Wind Monitor as a (NOAA) sensor and Clark Atlanta University (CAU) 0 190 191 192 193 194 195 196 197 198 50 correct data reference, we can assume that the Cup Anemometer had worked right. sensors, which are located on the rooftop of the Science Julian day Wind Monitor (NOAA) 0 190 191 192 193 194 195 196 197 198 Horizontal wind direction sensors However, the data collected for horizontal wind direction, the two sets of data, Research Center at CAU. The data was taken for a week Wind Vane ( CAU) Julian Day Wind Vane (CAU) from the Wind Monitor and the Wind Vane, had a constant number difference. Plotting Wind direction vs. Julian day from July 9 th to July 16 th 1999. The NOAA sensor was (corrected for angles < 360 degrees) Wind Monitor (NOAA) the wind direction from the two instruments against the Julian day (190- 198) on the the Wind Monitor-AQ model 05305 propeller 600 6 Wind Speed Vs Julian day same graph, we were able to tell the difference, which is almost a constant number that should have been added to the Cup Anemometer. anemometer, which measures both horizontal wind 500 Calculating the constant 5 speed and direction. The CAU sensors were the Wind direction(degrees) First, an offset value for matching the CAU data to the NOAA data for wind 400 4 direction was calculated. It was 171 degrees. Then, this offset was added to the wind Maximum # 40 Cup Anemometer for wind speed and 300 direction value to the CAU sensor. Plotting the two data sets together against the Julian Wind speed (m/s) 200 Series Wind Vane for wind direction. When the data 3 day, we found that the two data matched almost at all points. Since wind direction was plotted and analyzed, we assumed that data from the 200 2 o sensors work by rotating 360 , for the directions greater than one rotation, we subtracted NOAA Wind Monitor was correct and used it as a 100 o 360 to get to simple angles. 1 reference to study the response of CAU sensors. 0 190 192 194 196 197 198 0 190 192 196 197 198 191 193 195 191 193 194 195 Wind Vane ( CAU) Cup Anemometer (CAU) Julian day Wind Monitor ( NOAA) Julian day Wind Monitor ( NOAA) Conclusion Having analyzed the data using PSI PLOT software, we concluded t hat the CAU horizontal wind direction sensor collected incorrect data for the period of observation. Adding 171 degrees to the NOAA wind directions made the wind-vane readings correct. Further investigation showed that the CA U wind vane had been installed incorrectly with North-South directions reversed, and it was shown to be necessary to adjust the orientation of the wind vane.
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