Quality, precision and accuracy of the maximum No. 40 anemometer

Conference · Tue Dec 31 04:00:00 EST 1996

OSTI ID:447475

Obermeir, J ^[1]; Blittersdorf, D ^[2]

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1. Otech Engineering, Davis, CA (United States)
2. NRG Systems Inc., Hinesburg, VT (United States)

This paper synthesizes available calibration data for the Maximum No. 40 anemometer. Despite its long history in the wind industry, controversy surrounds the choice of transfer function for this anemometer. Many users are unaware that recent changes in default transfer functions in data loggers are producing output wind speed differences as large as 7.6%. Comparison of two calibration methods used for large samples of Maximum No. 40 anemometers shows a consistent difference of 4.6% in output speeds. This difference is significantly larger than estimated uncertainty levels. Testing, initially performed to investigate related issues, reveals that Gill and Maximum cup anemometers change their calibration transfer functions significantly when calibrated in the open atmosphere compared with calibration in a laminar wind tunnel. This indicates that atmospheric turbulence changes the calibration transfer function of cup anemometers. These results call into question the suitability of standard wind tunnel calibration testing for cup anemometers. 6 refs., 10 figs., 4 tabs.

• Research Organization: USDOE, Washington, DC (United States); National Renewable Energy Lab., Golden, CO (United States)
• OSTI ID: 447475
• Report Number(s): CONF-960630--; ON: DE97002833
• Country of Publication: United States
• Language: English

Related Subjects

17 WIND ENERGY
44 INSTRUMENTATION
INCLUDING NUCLEAR AND PARTICLE DETECTORS
ACCURACY
ANEMOMETERS
CALIBRATION
DATA COVARIANCES
PERFORMANCE TESTING
TRANSFER FUNCTIONS