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Title: Establishment Of A National Primary Standard For Air Speed Up To 90 m/s At Nmij
Author: A. Iwai T. Funaki N. Kurihara Y. Terao
Source: Flomeko 2016
Year Published: 2016
Abstract: NMIJ has established a high air speed standard facility and has been providing a calibration service since April 2015. The facility has an air spe ed range of 40 to 90 m/s with a relative expanded uncertainty ( k 2) of 0.63%. The purpose of this primary standard is mainly to contribute to the improvement of meteorological observation and research. The reference air speed is derived from the national p rimary gas flowrate standard of Japan. The contraction nozzle for conversion from flowrate to air speed is installed at the test line of the closed loop gas flowrate calibration facility. The standard air speed at the nozzle exit is obtained by comparing t he integral value of the air speed profile and the standard gas flowrate. The total pressure tube used as a transfer standard is then calibrated against the standard air speed at the nozzle exit. Using this total pressure tube, the Eiffel - type wind tunnel, which is a working standard for the daily calibration service, is calibrated. The present paper describes the calibration system, the traceability chain, and the uncertainty analysis of the new air speed standard.