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One-dimensional analysis of full load draft tube surge / Changkun Chen in Transactions of the ASME . Journal of fluids engineering, Vol. 130 N° 4 (Avril 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 4 (Avril 2008) . - 6 p. Titre : One-dimensional analysis of full load draft tube surge Type de document : texte imprimé Auteurs : Changkun Chen, Auteur ; Nicolet, Christophe, Auteur ; Koichi Yonezawa, Auteur Année de publication : 2009 Article en page(s) : 6 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Flow  (dynamics);  stress;  diffusers;  equations;  surges;  pressure;  cavities Résumé : One-dimensional stability analysis of a hydraulic system composed of a penstock, a runner, and a draft tube was carried out to determine the cause of the full load draft tube surge. It is assumed that the cavity volume at the runner exit is a function of the pressure at the vortex core evaluated from the instantaneous local pressure at the runner exit and an additional pressure decrease due to the centrifugal force on the swirling flow. It was found that the diffuser effect of the draft tube has a destabilizing effect over all flow rates, while the swirl effects stabilize∕destabilize the system at larger∕smaller flow rates than the swirl-free flow rate. Explanations of the destabilizing mechanism are given for the diffuser and swirl flow effects. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27307 [...] [article] One-dimensional analysis of full load draft tube surge [texte imprimé] / Changkun Chen, Auteur ; Nicolet, Christophe, Auteur ; Koichi Yonezawa, Auteur . - 2009 . - 6 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 4 (Avril 2008) . - 6 p. Mots-clés : Flow  (dynamics);  stress;  diffusers;  equations;  surges;  pressure;  cavities Résumé : One-dimensional stability analysis of a hydraulic system composed of a penstock, a runner, and a draft tube was carried out to determine the cause of the full load draft tube surge. It is assumed that the cavity volume at the runner exit is a function of the pressure at the vortex core evaluated from the instantaneous local pressure at the runner exit and an additional pressure decrease due to the centrifugal force on the swirling flow. It was found that the diffuser effect of the draft tube has a destabilizing effect over all flow rates, while the swirl effects stabilize∕destabilize the system at larger∕smaller flow rates than the swirl-free flow rate. Explanations of the destabilizing mechanism are given for the diffuser and swirl flow effects. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27307 [...]