4593 (RP-986) -- Uncertainty Analysis of the Experimental Results Investigating the Effects of Turbulence Intensity on the Performance of Rotating Vane Anemometers (same as HI-02-4-2) PDF

The experimental results of an investigation of the influence of various levels of turbulence intensity on the ability of rotating vane anemometers to accurately measure average air speed have been presented in a companion paper. Results were given for two different sizes of rotating vane anemometers detailing the error in rotating vane measurement. The two rotating vane anemometers were each tested at six different air speeds —100 fpm, 200 fpm, 500 fpm, 1000 fpm, 2500 fpm, and 5000 fpm —through a range of nominal turbulence intensities from 0.5% to 20%. The results suggest that turbulence intensity gives rise to significant errors of as much as 20% to 25% in vane anemometer performance, and that significant differences exist in the relative influence of turbulence intensity on the two different sizes of anemometers tested.

Because of its importance in quantitatively assessing the significance of the experimentally determined influence of turbulence intensity, this paper gives a detailed analysis of the uncertainty bands that were presented along with the previously presented experimental results. A description of the design of the statistical sampling procedure utilized in conducting this research project is given. Included in this paper is a detailed evaluation of the uncertainty of the resulting vane anemometer error, along with an assessment of the uncertainty in the imposed levels of turbulence intensity. In addition, a detailed investigation is presented of the uncertainty associated with each individual measurement system. Included among the measurement systems investigated here is the hot-film anemometry system, which was used as the measurement standard for determining the actual mean flow and turbulence intensity imposed on the rotating vane anemometers under test.

Units: I-P