Axial development of liquid turbulence and interfacial area in bubbly two-phase flow
In relation to the development of the interfacial area transport equation, local measurements of the void fraction, interfacial area concentration, interfacial velocity, and Sauter mean diameter using the double sensor probe method as well as the liquid velocity and turbulence intensity using hotfilm anemometry were performed extensively for vertical upward bubbly air-water flows in a round tube with an inner diameter of 25.4mm at three axial locations of L/D=12.0, 65.0 and 125, and fifteen radial locations from r/R=0 to 0.95. The liquid flow rate and the void fraction ranged from 0.292m/s to 3.49m/s and from 3% to 27%, respectively. The mechanisms on the radial profiles of local flow parameters and their axial developments were discussed. In order to understand the mechanism of one-dimensional interfacial area transport, the change of the interfacial area concentration due to the bubble coalescence and breakup {xi} was displayed as a function of the volumetric flow quality {beta}. For low liquid velocities, the bubble coalescence rates were increased gradually with the void fraction increases. In the flow region, although the increase in void fraction would promote the bubble-bubble interaction, the liquid turbulence might not be large enough to breakup the bubble. On the other hand, for high liquid velocities, the bubble breakup rates were increased with the void fraction, since the increase in void fraction decreased not only the distance between the bubble and the turbulent eddy but also the liquid velocity, namely the liquid turbulence. Thus, it turned out that the mechanism of the interfacial area transport depended on the bubble mixing length, turbulence intensity, void fraction, and so on. The combined data from the double sensor probe and the hot film probe gave the near complete information on the time averaged local hydrodynamic parameters of two-phase flow. The data set obtained in this study will eventually be used for the development of reliable constitutive relations which reflect the true transfer mechanisms in bubbly flow systems.
- Research Organization:
- Kyoto Univ., Sennan, Osaka (JP)
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 20026805
- Resource Relation:
- Conference: 5th ASME/JSME Thermal Engineering Joint Conference, San Diego, CA (US), 03/14/1999--03/19/1999; Other Information: 1 CD-ROM. Operating system required: Windows i386(tm), i486(tm), Pentium (R) or Pentium Pro, MS Windows 3.1, 95, or NT 3.51, 8 MB RAM, MacIntosh and Power MacIntosh with a 68020 or greater processor, System software version 7.1, 3.5 MB RAM (5 MB for PowerMac) 6 MB available hard-disk space, Unix; PBD: 1999; Related Information: In: Proceedings of the 5th ASME/JSME thermal engineering joint conference, [3600] pages.
- Country of Publication:
- United States
- Language:
- English
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