Flow characteristics of liquid films of annular two-phase flow in a curved double tube
Experimental studies were carried out to clarify the flow characteristics of liquid film of an annular two-phase flow in a curved double tube. The experiments were performed by an air-water two-phase flow in a C-shaped concentric double tube bend, the outside diameter of the outer tube was 25mm and the inside diameter of the inner tube was 16mm with a radius of curvature 250 mm. The test section was installed on a horizontal plane. Three systematic experiments were performed; measurement of film thickness distribution, flow rate distribution of liquid film and visual observation of liquid film. The former two experiments showed that, for the inner tube, the liquid flow rate has little influence on both the film thickness and film flow rate distributions, whereas for the outer tube, both values increase in the outside region with the increase of the liquid flow rate. By the visual observation, it was found that the liquid phase in the curved double tube moves toward outside by the disturbance wave and returns toward inside by the base liquid film. In addition, centrifugal forces acting on the disturbance wave, the base liquid film and the gas phase were calculated and compared with each other. Based on these experimental results, a mechanism of the formation of annular liquid film in the curved double tube was discussed as follows. The driving force of the outward movement of liquid phase is centrifugal force acting on the disturbance wave, while the driving force for the inward movement of liquid phase is shear force caused by a strong secondary flow in the gas phase. In addition to these forces, the deposition of the entrained droplets from the inner to the outer tube in the outside region or vice versa in the inside region makes the different film distribution profile between the outer and the inner tubes. The outside peak ({psi} = 270{degree}) in film flow rate distribution of the outer tube shown in Fig. A-2 is formed by the outward force acting on the disturbance waves along with the droplet transfer from the inner tube wall in the outside region. The inside peak ({psi} = 0{degree}) of the outer tube is caused by the increase of base film flow rate toward inside with the increase of gas flow rate which intensifies the secondary flow.
- Research Organization:
- Aichi Inst. of Tech., Toyota (JP)
- OSTI ID:
- 20026804
- 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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