Evaluation of the multi-sensor probe methods for the measurement of local bubble velocity and diameter

Abstract

The evaluation of the multi-sensor probe methodology is required to accurately measure local bubbles or droplet parameters in the two-phase flow conditions. This study evaluated two- and four-sensor probes through Monte Carlo simulation and air-water benchmark experiments. In the simulation, it was found that the lateral distance of sensing elements should be minimized, and their axial distance should be longer than 10% of bubble diameter for the optimal design of the probe. From the benchmark experiments, the Vb,axial uncertainties of two- and four-sensor probes were 6.5% and 4.5% in the velocity range of 0.4–3.7 m/s, respectively. The D32 uncertainty was significantly affected by the bubble shape and data reduction methods for each probe. For the two-sensor probe, the maximum error was 9% when the bubble shape was close to the sphere of which diameter was less than 2 mm, and it increased to 28% when the bubble diameter exceeded 2 mm due to the bubble shape distortion in the experiment. While, the four-sensor probe showed excellent performance with a 14% error regardless of the bubble shape under the distorted bubbly flow.