Tail Wind Speed
A sonic anemometer is located on the tail of the wind turbine just upwind of the tail fin at approximately 3.26 m 10.7 ft. from the rotor plane at the centerline of the shaft. Specifications for the sensor may be found in Appendix C. A sonic anemometer was located at hub height 24.4 m 80 ft on a meteorological tower Figure 11 located 19.8 m 64.9 ft upwind from the turbine and at a height of 24.4 m 80 ft . The distance from the sonic anemometer to the turbine was 3.5 rotor diameters for...
Turbine Configurations
Data were collected for three turbine configurations, A, B, and C, as summarized in Table 5 8 . Configuration A and B differ by the lateral offset distance between the rotor centerline and the yaw axis, which was 0.106 m in Configuration A and 0.083 m in Configuration B a 22 change . The change in the lateral offset for Configuration A was implemented by placing a 4-degree shim between the alternator and the shaft sensor. Figure 13 shows a schematic of the shim and the change in the lateral...
o Mean Flap Mom B Data a Max Flap Mom B ADAMS
Figure 50. 10-Minute mean, maximum, and minimum values of Blade 1 flap bending for The summary statistics for Configuration C do not include the site-specific turbulence inputs that were included in the Configuration A FAST summary statistics shown previously. Configuration C statistics use the IEC Category A turbulence conditions. Figure 51 shows the actual turbulence intensities for the test data as compared to the IEC test case. Figure 51. IEC Category A and test data turbulence intensities....
Thrust Shaft Bending and Torsion Moments
The shaft load fixture was built specifically for the SWRT test to measure thrust, shaft 0- and 90-degree bending, and torque. Figure 9 is a picture of the shaft load fixture, opened to show the four strain-gauged posts that carry all of the rotor loads. The shaft sensor is located on the nonrotating shaft i.e., fixed frame approximately 0.51 m 20.35 in from the rotor's center. Detailed calibration data for the sensor, including the coefficients for the 4 by 4 crosstalk calibration matrix, may...
Pretest Turbine Characterization
To supply inputs for aeroelastic models of the SWRT, the turbine tail assembly and main frame were weighed and center of gravities Cgs were determined. Tests were also conducted to calculate the inertia about the tail axis and the yaw axis. Tail damper properties were measured and all turbine geometries noted. A modal test was conducted for a blade to determine mode shapes for flap and edge. This data, as well as all turbine related parameters, including airfoil data, is contained in Appendix...
Yaw Position and Velocity
Yaw position and velocity were also measured using a high-speed, optical shaft encoder. The encoder is smiliar to the rotor speed and azimuth encoder and comes mounted on a slip ring that was used to get the signals from the rotating nacelle frame to the tower. The encoder outputs 512 pulses per rotor revolution. The yaw position signal is an analog signal. Yaw position is defined as positive in a counterclockwise direction from true north as shown in Figure 10. Specifications for the sensor...
Rotor Speed and Azimuth
Rotor speed and azimuth were measured using a high-speed, optical shaft encoder. The encoder, mounted on a slip ring, receives the signals from the rotating hub frame and sends them to the nacelle. The encoder outputs 512 pulses per rotor revolution. The hub azimuth and rotor speed are analog signals. Because the turbine rotates counterclockwise, rotor azimuth is positive in the counterclockwise direction with 0 degrees corresponding to blade 1 when it is vertical and pointing up....
Test Turbine Description
The SWRT is a modified Bergey EXCEL 10-kW turbine that furls horizontally out of the wind. The tail boom attaches with a hinge and bumper arrangement to the rotor generator main-frame assembly, and there is a lateral offset between the yaw axis and the rotor axis. The axis of the hinge pivot joint is inclined laterally at a small angle to the vertical yaw axis and produces a gravity restoring moment. A main-frame stop keeps the tail boom from furling more than about 68 degrees. There is a...
Calibration Procedures
The test engineer must follow defined procedures to perform calibrations. Whenever possible, the measurement chain from the sensor output through the data acquisition system is calibrated by generating known sensor outputs and recording the corresponding readings in the data acquisition system, i.e., an end-to-end calibration. Several points provide data for linear interpolation, and the slope and offset values of a linear transducer can then be determined. This form of calibration is used for...
Figure PSD of blade edge and flap moments
-Torque -Thrust-Shaft Tilt-Shaft Yaw-blade 3 flap-Blade 3 Edge Figure 16. PSD at 17.3 m s showing the effects of blade flutter at 34 hz Figures 17 through 20 show scatter plots of furl, yaw rate, electrical power, and rotor speed for Configuration A. The data show mean, maximum, and minimums plotted against mean wind speed. The average yaw error for Configuration A is between 15 and 20 degrees depending on wind speed. Because of space limitations, only scatter plots for Configuration A are...
Fast Furling Model
Jason Jonkman of NREL recently upgraded the FAST code to include furling effects 6 . The upgrades include a lateral thrust offset and skew angle of the rotor shaft from the yaw axis, rotor-fUrling and tail-furling degrees-of-freedom DOFs , up- and down-furl stops, and tail fin aerodynamics and inertia. The location and orientation of the new furling DOFs are completely user-specified, making the simulator flexible enough to model many furling wind turbine configurations. For example, to model a...