The flow characteristics of an upward gas‐liquid two‐phase flow in a vertical tube with a wire coil: Part 2. Effect on void fraction and liquid film thickness

Abstract

An experimental study has been carried out to clarify the characteristics of the void fraction and the liquid film thickness of the air‐water two‐phase flow in vertical tubes of 25‐mm inside diameter with wire coils of varying wire diameter and pitch. The flow pattern in the experiment on the average void fraction and the local void fraction distribution in cross section was a bubble flow, and the liquid film thickness was in the region of semiannular and annular flows. It is clarified from these experiments that the average void fraction in tubes with wire coils is lower than that in a smooth tube and decreases with the wire diameter owing to the centrifugal force of the swirl flow which concentrates bubbles at the center of the tube, that the local liquid film thickness becomes more uniform with a decrease in the pitch of the wire coil, and that the liquid film becomes thicker after the passage through the wire coil with an increase in the wire diameter. © 2002 Wiley Periodicals, Inc. Heat Trans Asian Res, 31(8): 652–664, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10067

Film thickness planar sensor in oil-water flow: prospective study

“…These methods have not been as extensively used as localized methods because, generally, they are harder to implement and the results are more difficult to analyze. Some examples are the needle contact probe (Takeshima et al, 2002), the hot-wire method (Franco, 2007) and the fiber-optic techniques (Addlesee and Cornwell, 1997). Spatial methods involve the performance of point or localized measurements simultaneously in different areas of the film to build up a global picture of the film thickness structure for the area under study.…”

Film thickness measurement with high spatial and temporal resolution planar capacitive sensing in oil-water pipe flow = Medida da espessura de filme usando sensor capacitivo de alta resolução espacial e temporal para escoamentos óleo-água em tubos

“…These methods have not been as extensively used as localized methods because, generally, they are harder to implement and the results more difficult to analyze. Some examples are the needle contact probe (TAKESHIMA et al, 2002), the hot-wire method (FRANCO, 2007) and the fiberoptic techniques (ADDLESEE & CORNWELL, 1997). Spatial Methods involve the performance of point or localized measurements simultaneously in different areas of the film in order to build up a global picture of the film thickness structure for the area under study.…”