In this article, we propose a novel ultrasonic technique to measure the gas void fraction in a liquid-gas intermittent swirling flow. The method converts the liquid film thickness measurement to a gas void fraction value considering a symmetrical flow pattern. We propose the use of the first echo peak instead of the standard maximum echo peak to estimate the liquid film thickness. The results are compared with a wire-mesh sensor, a reference for gas void fraction measurement, in a 1-inch inner-diameter vertical flow loop. A Root-Mean-Square-Deviation (RMSD) of 2.87% was observed between the proposed ultrasonic method and the reference sensor. An improvement of 6.06% if compared to the standard film thickness method (8.93%). The studied cases show that our method improves the use of ultrasound for gas void fraction measurement in a gas-liquid swirling flow.
