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Computational and experimental studies on cavity filling process by cold gas dynamic spray / Hidemasa Takana in Transactions of the ASME . Journal of fluids engineering, Vol. 132 N° 2 (Fevrier 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 2 (Fevrier 2010) . - 09 p. Titre : Computational and experimental studies on cavity filling process by cold gas dynamic spray Type de document : texte imprimé Auteurs : Hidemasa Takana, Auteur ; HongYang Li, Auteur ; Kazuhiro Ogawa, Auteur Année de publication : 2010 Article en page(s) : 09 p. Note générale : fluids engineering Langues : Anglais (eng) Résumé : Time-dependent computational simulations on cavity filling process by cold gas dynamic spray and powder jet deposition process ranging from microscale to macroscale were carried out in order to give an insight for their advanced applications to joining, crack repair, and dental treatment. Shock wave appears in front of the substrate due to underexpansion of jet and in-flight particles interact with the shock wave before their impact. The relation between shock wave, cavity configuration, and particle in-flight behavior in supersonic jet has been discussed in detail. Based on numerical and experimental studies, it was found that when the shock wave covers up the cylindrical cavity, the cavity cannot be filled at all by deposited powders. Moreover, under the condition of shock wave appearing inside the cylindrical cavity, conical deposition was formed due to the secondary back flow jet along the cavity side wall. By adopting conical cavity, cavity can be filled completely resulting from the suppression of the secondary back flow jet along the cavity side wall. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27408 [...] [article] Computational and experimental studies on cavity filling process by cold gas dynamic spray [texte imprimé] / Hidemasa Takana, Auteur ; HongYang Li, Auteur ; Kazuhiro Ogawa, Auteur . - 2010 . - 09 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 2 (Fevrier 2010) . - 09 p. Résumé : Time-dependent computational simulations on cavity filling process by cold gas dynamic spray and powder jet deposition process ranging from microscale to macroscale were carried out in order to give an insight for their advanced applications to joining, crack repair, and dental treatment. Shock wave appears in front of the substrate due to underexpansion of jet and in-flight particles interact with the shock wave before their impact. The relation between shock wave, cavity configuration, and particle in-flight behavior in supersonic jet has been discussed in detail. Based on numerical and experimental studies, it was found that when the shock wave covers up the cylindrical cavity, the cavity cannot be filled at all by deposited powders. Moreover, under the condition of shock wave appearing inside the cylindrical cavity, conical deposition was formed due to the secondary back flow jet along the cavity side wall. By adopting conical cavity, cavity can be filled completely resulting from the suppression of the secondary back flow jet along the cavity side wall. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27408 [...]

Computational simulation on performance enhancement of cold gas dynamic spray processes with electrostatic assist / Hidemasa Takana in Transactions of the ASME . Journal of fluids engineering, Vol. 130 N° 8 (Août 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 7 p. Titre : Computational simulation on performance enhancement of cold gas dynamic spray processes with electrostatic assist Type de document : texte imprimé Auteurs : Hidemasa Takana, Auteur ; Kazuhiro Ogawa, Auteur ; Tetsuo Shoji, Auteur Année de publication : 2009 Article en page(s) : 7 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Force;  flow  (dynamics);  particulate  matter;  simulation;  sprays;  flight;  coating  processes;  coatings;  shock  waves;  drag  (fluid  dynamics);  lift  (fluid  dynamics) Résumé : A real-time computational simulation on the entire cold spray process is carried out by the integrated model of compressible flow field, splat formation model, and coating formation model, in order to provide the fundamental data for the advanced high performance cold gas dynamic spray process with electrostatic acceleration. In this computation, viscous drag force, flow acceleration added mass, gravity, Basset history force, Saffman lift force, Brownian motion, thermophoresis, and electrostatic force are all considered in the particle equation of motion for the more realistic prediction of in-flight nano∕microparticle characteristics with electrostatic force and also for the detailed analysis of particle-shock-wave-substrate interaction. Computational results show that electrostatic acceleration can broaden the smallest size of applicable particle diameter for successful adhesion; as a result, wider coating can be realized. The utilization of electrostatic acceleration enhances the performance of cold dynamic spray process even under the presence of unavoidable shock wave. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27329 [...] [article] Computational simulation on performance enhancement of cold gas dynamic spray processes with electrostatic assist [texte imprimé] / Hidemasa Takana, Auteur ; Kazuhiro Ogawa, Auteur ; Tetsuo Shoji, Auteur . - 2009 . - 7 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 7 p. Mots-clés : Force;  flow  (dynamics);  particulate  matter;  simulation;  sprays;  flight;  coating  processes;  coatings;  shock  waves;  drag  (fluid  dynamics);  lift  (fluid  dynamics) Résumé : A real-time computational simulation on the entire cold spray process is carried out by the integrated model of compressible flow field, splat formation model, and coating formation model, in order to provide the fundamental data for the advanced high performance cold gas dynamic spray process with electrostatic acceleration. In this computation, viscous drag force, flow acceleration added mass, gravity, Basset history force, Saffman lift force, Brownian motion, thermophoresis, and electrostatic force are all considered in the particle equation of motion for the more realistic prediction of in-flight nano∕microparticle characteristics with electrostatic force and also for the detailed analysis of particle-shock-wave-substrate interaction. Computational results show that electrostatic acceleration can broaden the smallest size of applicable particle diameter for successful adhesion; as a result, wider coating can be realized. The utilization of electrostatic acceleration enhances the performance of cold dynamic spray process even under the presence of unavoidable shock wave. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27329 [...]