Uncertainty analysis of the air velocity standard based on LDA and wind tunnel

Abstract

This paper deals with uncertainty analysis an air velocity standard consisting of a wind tunnel and a laser Doppler anemometer (LDA) measuring system. The analysis is performed for air velocities between 0.3 m/s and 40 m/s, and a calibration procedure with the readings from the LDA and the device under test (DUT) taken simultaneously. The calculation of the reference air velocity includes a systematic correction of the velocity measured by the LDA to the position of the DUT. The study provides a complete and detailed methodology for estimating all major uncertainty contributions attributed to the LDA standard, position correction including velocity field uniformity, stability and uncorrected blockage effect. The contribution of the blockage effect was estimated for three different anemometers. For the Pitot static tube, the contribution of position correction predominates; however, for the other two larger anemometers, the contribution of the uncorrected blockage effect predominates at higher velocities.