A comprehensive study on the effect of cavitation on injection velocity in diesel nozzles
Results when testing cavitating injection nozzles show a strong reduction in mass flow rate when cavitation appears (the flow is choked), while the momentum flux is reduced to a lesser extent, resulting in an increase in effective injection velocity. So as to better understand the origin of this inc...
| Autores: | , , , |
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| Tipo de documento: | artigo |
| Data de publicação: | 2012 |
| País: | España |
| Recursos: | Universitat Politècnica de València (UPV) |
| Repositório: | RiuNet. Repositorio Institucional de la Universitat Politécnica de Valéncia |
| Idioma: | inglês |
| OAI Identifier: | oai:riunet.upv.es:10251/72768 |
| Acesso em linha: | https://riunet.upv.es/handle/10251/72768 |
| Access Level: | Acceso aberto |
| Palavra-chave: | Injection velocity Nozzle cavitation Velocity profile Basic equations Comprehensive studies Indirect effects Injection holes Injection nozzles Mass flow rate Momentum conservations Momentum flux Profile shapes Top hat Velocity profiles Cavitation Momentum Nozzles Pipe flow Vapors Velocity MAQUINAS Y MOTORES TERMICOS |
| Resumo: | Results when testing cavitating injection nozzles show a strong reduction in mass flow rate when cavitation appears (the flow is choked), while the momentum flux is reduced to a lesser extent, resulting in an increase in effective injection velocity. So as to better understand the origin of this increase in effective injection velocity, the basic equations for mass and momentum conservation were applied to an injection nozzle in simplified conditions. The study demonstrated that the increase in injection velocity provoked by cavitation is not a direct effect of the latter, but an indirect effect. In fact, the vapor appearance inside the injection hole produces a decrease in the viscosity of the fluid near the wall. This leads to lower momentum flux losses and to a change in the velocity profile, transforming it into a more "top hat" profile type. This change in the profile shape allows explaining why the momentum flux reduction is not so important compared to that of the mass flow rate, thus explaining why the effective injection velocity increases. © 2012 Elsevier Ltd. All rights reserved. |
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