Interfacial area transport due to shear collision of bubbly flow in small-diameter pipes

• Published in: Nuclear engineering and design Vol. 310; pp. 592 - 603
• Main Authors: Hazuku, Tatsuya, Hibiki, Takashi, Takamasa, Tomoji
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15-12-2016; Elsevier BV
• Subjects: Adiabatic; Adiabatic flow; Bubbly flow; Datasets; Entrainment; Error analysis; Fluid flow; Fluids; Interfacial area transport equation; Microgravity; Mini pipe; Pipes; Shear collision; Small-diameter pipe; Standard deviation; Studies; Transport equations; Bubbly flow; Shear collision; Mini pipe; Microgravity; Interfacial area transport equation; Small-diameter pipe
• ISSN: 0029-5493; 1872-759X
• DOI: 10.1016/j.nucengdes.2016.10.041

•The dominant mechanism in interfacial area transport in small pipes was identified.•A sink term of interfacial area was modeled with shear collision mechanism.•The developed sink term was evaluated by using 74 datasets.•The developed model satisfactorily agreed with the measured data.
In view of the practical importance of the interfacial area transport equation in flow analysis based on the two-fluid model, especially for flow analysis in a reactor core which has a relatively small channel configuration, the dominant mechanism in the interfacial area transport in small diameter pipes was firstly identified by evaluating the experimental data obtained for pressurized bubbly flows under microgravity, where the source and sink terms of the interfacial area concentration due to bubble expansion and wake entrainment collision are negligible. The sink term of the interfacial area concentration of bubbly flow in small diameter pipe was modeled in terms of the shear collision mechanism. The one-dimensional interfacial area transport equation with the developed sink term was evaluated by using 74 datasets obtained for adiabatic gas-liquid bubbly flows, including upward flows and microgravity flows in pipes with inside diameters of 9.0, 5.0 and 3.0mm. A detailed discussion was provided on the interfacial area transport mechanism in small-diameter pipe. The overall standard deviation of the absolute error between predicted and measured interfacial area concentrations was 11.8%. The present model will reproduce the interfacial area transport of bubbly two-phase flows in small-diameter pipes with inside diameters of 3.0–9.0mm, at superficial liquid and gas velocities over the ranges 〈jf〉=0.073–0.949m/s, and 〈jg〉=0.00434–0.0500m/s, and also over a wide range of axial distances, z/D=5–188.