Bubble plumes and the Coanda effect
This paper describes the mean gas fraction distribution in the two-phase flow of a gas–liquid bubble plume set to develop adjacent either to a wall or to another bubble plume. When this happens, the plume exhibits a type of Coanda effect, bending either towards the wall or the other plume. The local...
| Autores: | , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2002 |
| País: | Brasil |
| Institución: | Universidade Federal do Rio de Janeiro (UFRJ) |
| Repositorio: | Repositório Institucional da UFRJ |
| Idioma: | inglés |
| OAI Identifier: | oai:pantheon.ufrj.br:11422/8832 |
| Acceso en línea: | http://hdl.handle.net/11422/8832 |
| Access Level: | acceso abierto |
| Palabra clave: | Bubble plume Coanda effect Entrainment CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA::AREAS CLASSICAS DE FENOMENOLOGIA E SUAS APLICACOES::DINAMICA DOS FLUIDOS |
| Sumario: | This paper describes the mean gas fraction distribution in the two-phase flow of a gas–liquid bubble plume set to develop adjacent either to a wall or to another bubble plume. When this happens, the plume exhibits a type of Coanda effect, bending either towards the wall or the other plume. The local mean gas fraction measurements are carried out using the electro-resistivity probe technique in an air–water system. The deflection angle of the plumes is shown to present a dependence on the modified Weber and Froude numbers of the bubbles. A Gaussian distribution for the mean gas fraction profile, observed to exist for axisymmetric single plumes, is shown not to occur in flow geometries where the Coanda effect is allowed to set in. The transition zone between the downstream flow where two Gaussian plumes are observed and the far upstream flow where the plumes are seen to merge onto a single plume is characterized. Photographs of the flow are shown to illustrate the phenomenon. Results are present for two- and three-dimensional mean gas fraction distributions. In addition, a simple theory based on integral methods is advanced for the prediction of the plume deflection angle; the theory considers a variable entrainment co-efficient. |
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