Void fraction and phase distribution of a rotating two-phase gas-liquid flow around a plasma arc under water
- Universitat Hannover (Germany). Institut fur Verfahrenstechnik
Plasma arc welding processes are used in off-shore industry for construction and maintenance in the wet surrounding of underwater structures and pipelines. In greater water depth the density of the plasma gas increase because of the greater hydrostatic pressure. This causes the increase of conductive heat losses to the wet surrounding. To keep up the energy flux to the workpiece to be welded, the plasma arc has to burn in a local dry area with an inside pressure of 1 bar. This requirement can be fulfilled by a rotating cylinder with a liquid film flowing down the inner wall. The flow around the rotating cylinder to create a local dry area around the plasma arc under water is experimentally investigated. The rotating cylinder is placed above the work surface which is simulated by a flat plate. According to the centrifugal forces of the rotating flow inside the gap between the lower end of the cylinder and the flat plate the water is forced out of the cylinder. The velocity distribution in the flow is measured by Laser-Doppler anemometry. The phase distribution in the two-phase flow in the gap is measured by local electrical probes. The static pressure inside the gaseous atmosphere is reduced in comparison to the hydrostatic pressure of the surrounding water. The pressure reduction is given by the void fraction, the phase distribution and the volume flow rates of both phases in the gap as well as by the speed of revolution and the design of the cylinder and the work surface. The influence of these parameters on the heat transfer from the workpiece to the two-phase flow regime is also investigated.
- OSTI ID:
- 100929
- Report Number(s):
- CONF-940659-; ISBN 0-7918-1373-8; TRN: IM9540%%403
- Resource Relation:
- Conference: 1994 American Society of Mechanical Engineers (ASME) Fluids Engineering Division summer meeting, Lake Tahoe, NV (United States), 19-23 Jun 1994; Other Information: PBD: 1994; Related Information: Is Part Of Cavitation and gas-liquid flow in fluid machinery and devices. FED-Volume 190; O`Hern, T.J.; Kim, J.H.; Morgan, W.B.; Furuya, O. [eds.]; PB: 350 p.
- Country of Publication:
- United States
- Language:
- English
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