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Thermodynamic effect on cavitation performances and cavitation instabilities in an inducer / Kengo Kikuta in Transactions of the ASME . Journal of fluids engineering, Vol. 130 N° 11 (Novembre 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 11 (Novembre 2008) . - 8 p. Titre : Thermodynamic effect on cavitation performances and cavitation instabilities in an inducer Type de document : texte imprimé Auteurs : Kengo Kikuta, Auteur ; Yoshida, Yoshiki, Auteur ; Mitsuo Watanabe, Auteur Année de publication : 2009 Article en page(s) : 8 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Cavitation;  cavities;  nitrogen;  water;  temperature Résumé : Based on the length of the tip cavitation as an indication of cavitation, we focused on the effect of thermodynamics on cavitation performances and cavitation instabilities in an inducer. Comparison of the tip cavity length in liquid nitrogen (76K and 80K) as working fluid with that in cold water (296K) allowed us to estimate the strength of the thermodynamic effect on the cavitations. The degree of thermodynamic effect was found to increase with an increase of the cavity length, particularly when the cavity length extended over the throat of the blade passage. In addition, cavitation instabilities occurred both in liquid nitrogen and in cold water when the cavity length increased. Subsynchronous rotating cavitation appeared both in liquid nitrogen and in cold water. In the experiment using liquid nitrogen, the temperature difference between 76K and 80K affected the range in which the subsynchronous rotating cavitation occurred. In contrast, deep cavitation surge appeared only in cold water at lower cavitation numbers. From these experimental results, it was concluded that when the cavity length extends over the throat, the thermodynamic effect also affects the cavitation instabilities as a “thermal damping” through the unsteady cavitation characteristics. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Thermodynamic effect on cavitation performances and cavitation instabilities in an inducer [texte imprimé] / Kengo Kikuta, Auteur ; Yoshida, Yoshiki, Auteur ; Mitsuo Watanabe, Auteur . - 2009 . - 8 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 11 (Novembre 2008) . - 8 p. Mots-clés : Cavitation;  cavities;  nitrogen;  water;  temperature Résumé : Based on the length of the tip cavitation as an indication of cavitation, we focused on the effect of thermodynamics on cavitation performances and cavitation instabilities in an inducer. Comparison of the tip cavity length in liquid nitrogen (76K and 80K) as working fluid with that in cold water (296K) allowed us to estimate the strength of the thermodynamic effect on the cavitations. The degree of thermodynamic effect was found to increase with an increase of the cavity length, particularly when the cavity length extended over the throat of the blade passage. In addition, cavitation instabilities occurred both in liquid nitrogen and in cold water when the cavity length increased. Subsynchronous rotating cavitation appeared both in liquid nitrogen and in cold water. In the experiment using liquid nitrogen, the temperature difference between 76K and 80K affected the range in which the subsynchronous rotating cavitation occurred. In contrast, deep cavitation surge appeared only in cold water at lower cavitation numbers. From these experimental results, it was concluded that when the cavity length extends over the throat, the thermodynamic effect also affects the cavitation instabilities as a “thermal damping” through the unsteady cavitation characteristics. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Thermodynamic effect on rotating cavitation in an inducer / Yoshida, Yoshiki in Transactions of the ASME . Journal of fluids engineering, Vol. 131 N° 9 (Septembre 2009) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 9 (Septembre 2009) . - 07 p. Titre : Thermodynamic effect on rotating cavitation in an inducer Type de document : texte imprimé Auteurs : Yoshida, Yoshiki, Auteur ; Yoshifumi Sasao, Auteur ; Mitsuo Watanabe, Auteur Année de publication : 2009 Article en page(s) : 07 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : cryogenic  fluids;  cavitation;  turbopump  inducer Résumé : Cavitation in cryogenic fluids has a thermodynamic effect because of the thermal imbalance around the cavity. It improves cavitation performances in turbomachines due to the delay of cavity growth. The relationship between the thermodynamic effect and cavitation instabilities, however, is still unknown. To investigate the influence of the thermodynamic effect on rotating cavitation appeared in the turbopump inducer, we conducted experiments in which liquid nitrogen was set at different temperatures (74 K, 78 K, and 83 K) with a focus on the cavity length. At higher cavitation numbers, supersynchronous rotating cavitation occurred at the critical cavity length of Lc/h≅0.5 with a weak thermodynamic effect in terms of the fluctuation of cavity length. In contrast, synchronous rotating cavitation occurred at the critical cavity length of Lc/h≅0.9–1.0 at lower cavitation numbers. The critical cavitation number shifted to a lower level due to the suppression of cavity growth by the thermodynamic effect, which appeared significantly with rising liquid temperature. The unevenness of cavity length under synchronous rotating cavitation was decreased by the thermodynamic effect. Furthermore, we confirmed that the fluid force acting on the inducer notably increased under conditions of rotating cavitation, but that the amplitude of the shaft vibration depended on the degree of the unevenness of the cavity length through the thermodynamic effect. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Thermodynamic effect on rotating cavitation in an inducer [texte imprimé] / Yoshida, Yoshiki, Auteur ; Yoshifumi Sasao, Auteur ; Mitsuo Watanabe, Auteur . - 2009 . - 07 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 9 (Septembre 2009) . - 07 p. Mots-clés : cryogenic  fluids;  cavitation;  turbopump  inducer Résumé : Cavitation in cryogenic fluids has a thermodynamic effect because of the thermal imbalance around the cavity. It improves cavitation performances in turbomachines due to the delay of cavity growth. The relationship between the thermodynamic effect and cavitation instabilities, however, is still unknown. To investigate the influence of the thermodynamic effect on rotating cavitation appeared in the turbopump inducer, we conducted experiments in which liquid nitrogen was set at different temperatures (74 K, 78 K, and 83 K) with a focus on the cavity length. At higher cavitation numbers, supersynchronous rotating cavitation occurred at the critical cavity length of Lc/h≅0.5 with a weak thermodynamic effect in terms of the fluctuation of cavity length. In contrast, synchronous rotating cavitation occurred at the critical cavity length of Lc/h≅0.9–1.0 at lower cavitation numbers. The critical cavitation number shifted to a lower level due to the suppression of cavity growth by the thermodynamic effect, which appeared significantly with rising liquid temperature. The unevenness of cavity length under synchronous rotating cavitation was decreased by the thermodynamic effect. Furthermore, we confirmed that the fluid force acting on the inducer notably increased under conditions of rotating cavitation, but that the amplitude of the shaft vibration depended on the degree of the unevenness of the cavity length through the thermodynamic effect. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]