A Comparative Study of the Dynamic Performance of Three Bivanes
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
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The dynamic performances of three multi-directional wind vanes, or bivanes, are studied and compared for the purpose of determining which bivane responds the fastest to changes in wind direction, with acceptable accuracy. The manufacturers of these bivanes are the R. M. Young Co., Teledyne Geotech, and Climatronics Corp. The procedures for testing the bivanes include evaluations on the static and dynamic characteristics of each bivane, and comparing how well each conforms to published standards. The static tests determined the accuracy and linearity of each bivane. Deviations from the ideal linear response were used to correct the dynamic test data. The dynamic tests were performed in the large Civil Engineering wind tunnel at wind speeds of 5 and 10 m s-1. The bivanes were released from six positions and allowed to return to the equilibrium angle. All three bivanes produced second-order underdamped responses necessary to rapidly adjust to a change in wind direction. Using the times of the first peak and second zero-crossing, the damping ratio, and natural wavelength, were calculated. The Xn described how well and fast the bivane responds to changes in wind direction. Apart from technical irregularities in a portion of the electronics, the Climatronics Dual Annulus Bivane responded the quickest and appears to be the best bivane for yielding wind components. In a subsequent study, the wind measurements from this bivane will be used to compute vertical flux of horizontal momentum in accordance with the techniques described by Chimonas 1980.
- Test Facilities, Equipment and Methods