Introduction There are several sensors for measuring wind speed by pharmphresh33

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									                                                                                                                                                                                                                                                                                                                                                                                                                                   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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