BLOW-DOWN CALIBRATION OF A LARGE 8 PATH ULTRASONIC FLOW METER UNDER QUASI-STEADY FLOW CONDITIONS

A. JOHNSON, E. HARMAN, J. BOYD

Abstract

We used an array of critical flow venturis (CFVs) in a blow-down facility to calibrate a large (D = 89.5 cm) 8 path ultrasonic flow meter at atmospheric pressure. The calibration was performed with dry air spanning the flow range 2 kg/s to 36 kg/s. At the largest flows, pressure transients associated with the blow-down system resulted in quasi-steady flow conditions. The quasi-steady conditions were measured using a high speed data acquisition system that scanned 66 instruments (i.e., pressure and temperature sensors) every 1.8 s. Corrections were made for thermal lag of the RTD temperature sensors, and for mass storage effects in the 230.3 m³ connecting volume between the CFV array and the ultrasonic flow meter. The uncertainty of the calibration (with coverage factor <i>k</i> = 2 corresponding to 95 % confidence level) ranged from 0.45 % to 0.58 %.

Keywords

CFVN, ultrasonic, flow meter, 8-path, blow-down

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IMEKO-TC9-2013-100.pdf

DOI

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IMEKO TC

TC9 - Flow Measurement

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