Effects of Reynolds number and aspect ratio on the opposed-jet flow instability
The effects of Reynolds number and aspect ratio on the distinct resulting flow regimes in an opposed-jet configuration are analyzed. The solution of the isothermal governing equations have been obtained in the two-dimensional case by means of Phoenics-2009 software for unsteady, unbounded, incompres...
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| Tipo de recurso: | informe técnico |
| Fecha de publicación: | 2010 |
| País: | España |
| Institución: | Universitat Politècnica de Catalunya (UPC) |
| Repositorio: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglés |
| OAI Identifier: | oai:upcommons.upc.edu:2117/439506 |
| Acceso en línea: | https://hdl.handle.net/2117/439506 |
| Access Level: | acceso abierto |
| Palabra clave: | Jets -- Fluid dynamics Dinàmica de fluids Àrees temàtiques de la UPC::Física::Física de fluids |
| Sumario: | The effects of Reynolds number and aspect ratio on the distinct resulting flow regimes in an opposed-jet configuration are analyzed. The solution of the isothermal governing equations have been obtained in the two-dimensional case by means of Phoenics-2009 software for unsteady, unbounded, incompressible flows. The pressure and velocity fields have been obtained for different values of nozzle separations, ranging from 5 to 50 nozzle diameters, and for Reynolds numbers ranging from Re = 10 to Re = 2000. For separations of h = 9d, where d is the nozzle diameter, the steady symmetric solution becomes unstable and loses its symmetry respect to stagnation line as well as to the axial direction. As a result, the opposed jets start to deflect with a fixed frequency and increasing amplitude, until a chaotic behavior is reached. For large aspect ratios, no periodic patterns appear in the transition between the unstable steady solution and the chaotic solution. For the case of nozzle separation equal to 10 diameters, a new type of instability has been found at Re = 1000. This instability appears as capillary waves in the outgoing jets and can be inhibited by turbulent mechanisms. |
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