Experimental study of slug and churn flows in a vertical pipe using plug-in optical fiber and conductance sensors

• Published in: Experimental thermal and fluid science 2019-10, Vol.107, p.16-28
• Main Authors: Yang, Q.Y., Jin, N.D., Zhai, L.S., Wang, D.Y., Wang, F.
• Format: Article
• Language: English
• Subjects: Churn flow; Conductance; Deformation; Gas-liquid two-phase flow; Optical fibers; Pipes; Plug-in optical fiber and conductance sensors; Resistance; Semiannular flow; Sensors; Slug flow; Void fraction
• ISSN: 0894-1777; 1879-2286
• DOI: 10.1016/j.expthermflusci.2019.05.005

•We design a novel plug-in sensor combined optical probe and conductance sensors.•We obtain local gas holdup, velocity and instantaneous gas chord lengths in 7 radial positions.•We find that big deformed bubbles in churn flow spiraling up in test pipe.•We analyze bubble chord length distributions in liquid slug of slug and churn flows. It is of great significance to explore the flow structures in gas-liquid slug and churn flows. Aiming at this purpose, a novel plug-in optical probe combined with conductance sensors are designed. Furthermore, we perform experimental study of gas-liquid flows in vertical upward pipe with 20 mm inner diameter. Simultaneously, the local time average of void fraction in axial direction, cross-correlation velocity and instantaneous bubble chord distribution in slug and churn flows at seven radial positions are obtained. The research results show that big deformed bubbles in churn flow spiral up in test pipe, but sometimes they rise along pipe center just as gas slugs in slug flow. Besides, bubble chord length distributions in liquid slug of slug and churn flows are analyzed in this study.