An Exploratory Experimental Technique to Predict Two-Phase Flow Pattern From Vibration Response

Abstract

Gas-liquid pipe flow is common in nuclear, gas & oil, refrigeration and power generation industries, where gas-liquid mixtures are transported in piping systems. The mixtures flows in different flow patterns, such as bubbly, slug and annular, generating dynamic fluid forces which may induce structural vibration. In many industrial cases, Flow-Induced Vibrations (FIV) are an intrinsic part of the piping operation and does not present risks that may lead to structural component failures. In this sense, the information available on this topic is quite scanty. In this paper, we present an in-depth discussion about the phenomenology of the FIV due to two-phase pipe flow. A set of 32 two-phase horizontal flow conditions was collected, including bubbly, slug and dispersed flow-patterns. The homogeneous mixture velocity J was in the range of 0.5 to 25 m/s, with homogeneous void fractions of β = 10%, 25%, 50%, 75% and 95%. Signals of acceleration were acquired to correlate pipe vibration and two-phase flow parameters. Results show higher acceleration levels in slug and dispersed than in bubbly flow. We find that the acceleration frequency response contains useful information of the flow. Comparisons with single-phase flow are also presented. Finally, an exploratory experimental technique to predict two-phase flow pattern from vibration response based on the combination resonance caused by both single and two-phase flow is proposed. The results indicate that the proposed-technique is acceptable to recognize intermittent flow patterns in two-phase flow.