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|Author(s):||Iosif I. Shinder; J. M. Hall; Michael R. Moldover;|
|Title:||Improved NIST Airspeed Calibration Facility|
|Published:||March 23, 2010|
|Abstract:||The National Institute of Standards and Technology (NIST) uses a laser Doppler anemometer (LDA) as a working standard for airspeed calibrations in the range 0.15 m/s to 75 m/s (0.34 to 168 miles/hour). We report improved procedures for calibrating the LDA that reduced its uncertainty from 0.26% to 0.10% at airspeeds above 1 m/s. (Uncertainties are stated with the coverage factor k=2 which corresponds to a 95 % confidence level.) The calibration uses a rotating disk with known dimensions at several known rotation frequencies, thereby tracing the LDA to the primary standards of length and time. We also improved the LDA signal-to-noise ratio in NIST‰s wind tunnel, particularly at higher air speeds, by replacing a water seeding system with an oil seeding system. New software automates the airspeed setting, oil-seeding rate, data-collection time, and instrument averaging time.|
|Proceedings:||Measurement Science Conference Proceedings|
|Dates:||March 22-26, 2010|
|Keywords:||atomizers, airspeed calibrations, laser Doppler anemometer, primary standards|
|Research Areas:||Traceability, Measurement Services, Measurement Systems, Measurements, Quality|
|PDF version:||Click here to retrieve PDF version of paper (841KB)|