Slug flow identification using ultrasound Doppler velocimetry

An identification method of slug flow using velocity information was developed in this study. Quantitative analysis of two-phase (gas-liquid) flow in horizontal pipes is essential to ensure the stability of, or to accurately estimate the thermal performance of, various engineering applications. The spatial and temporal distribution of liquid velocity was measured using the ultrasound Doppler velocimetry method under various superficial velocity conditions. From the results, we proposed a novel identification method of the slug flow based on two parameters, the maximum velocity and maximum velocity difference ratio. In addition, the ratio of liquid velocities between the slug body and the bubble area is a reliable parameter for separating the slug flow from the plug flow. Finally, we investigated the changes in moving velocity, slug frequency, and slug length along the pipeline under a wide range of superficial velocities. The results show that the liquid and gas superficial velocity have the opposite effect on the slug frequency, except in the downstream region. It was found that the slug body length increased continually along the pipe and the average slug body length in the downstream region is invariant regardless of the gas superficial velocity. (C) 2019 Elsevier Ltd. All rights reserved.