Uncertainty quantification of low void fraction measurements using wire-mesh sensors in horizontal air-water flows

Two-phase flow tests were performed at a low-pressure, adiabatic and horizontal flow loop using wire-mesh sensors over a range of liquid superficial velocities from 3.5 to 5.5 m/s, gas superficial velocities of from 0.06 to 0.9 m/s and volumetric void fractions from 2 to 16%. A revision to the single-phase calibration procedure was proposed in order to more accurately post-process the wire-mesh sensor voltage signals under the given flow conditions. Using this proposed analysis, a corrected trend with average percent differences of 36%, 21% and 6% was obtained for the low, medium and high gas flow rate cases, respectively, when comparing the wire-mesh sensor void fractions to two-phase pipe flow models. By combining these measurements of the void fraction with those of the interfacial velocity, the gas superficial velocity was calculated based on the physical theory, and compared to the superficial velocity measured by the flowmeters for validation purposes. An estimation of the uncertainty of these parameters showed that most of the measured parameters agreed reasonably with physical theory within 20%. (author)