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Influence of geometry on starting vortex and ejector performance / Zheng, Fei in Transactions of the ASME . Journal of fluids engineering, Vol. 133 N° 5 (Mai 2011) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 08 p. Titre : Influence of geometry on starting vortex and ejector performance Type de document : texte imprimé Auteurs : Zheng, Fei, Auteur ; Andrey V. Kuznetsov, Auteur ; Roberts, William L., Auteur Année de publication : 2011 Article en page(s) : 08 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Acoustic  waves  Detonation  waves  Engines  Jets  Navier-Stokes  equations  Propulsion  Vortices Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : For many propulsion devices, the thrust may be augmented considerably by adding a passive ejector, and these devices are especially attractive for unsteady propulsion systems such as pulse detonation engines and pulsejets. Starting vortices from these unsteady devices dominate the flowfield and control to a great extent the level of the thrust augmentation. Therefore, it is of fundamental interest to understand the geometric influences on the starting vortex and how these manifest themselves in augmenter/ejector performance. An unsteady Reynolds averaged Navier–Stokes calculation was used to study the physics of a starting vortex generated at the exit of a pulsed jet and its interaction with an ejector. A 50 cm long pulsejet (typical hobby scale, allowing comparison with experimental data) with a circular exit was modeled as the resonant driving source and used to suggest an optimal ejector geometry and relative position. Computed limit-cycle thrust augmentation values compared favorably to experimentally obtained values for the same ejector geometries. Results suggest that the optimal diameter of the ejector is related to its relative position, dictated by the trajectory of the vortex toroid. The effect of the length of the ejector (which determines the natural frequency of the ejector, related to the acoustic processes occurring in the ejector) on overall performance was also investigated and shown to be less important than the ejector diameter. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...] [article] Influence of geometry on starting vortex and ejector performance [texte imprimé] / Zheng, Fei, Auteur ; Andrey V. Kuznetsov, Auteur ; Roberts, William L., Auteur . - 2011 . - 08 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 133 N° 5 (Mai 2011) . - 08 p. Mots-clés : Acoustic  waves  Detonation  waves  Engines  Jets  Navier-Stokes  equations  Propulsion  Vortices Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : For many propulsion devices, the thrust may be augmented considerably by adding a passive ejector, and these devices are especially attractive for unsteady propulsion systems such as pulse detonation engines and pulsejets. Starting vortices from these unsteady devices dominate the flowfield and control to a great extent the level of the thrust augmentation. Therefore, it is of fundamental interest to understand the geometric influences on the starting vortex and how these manifest themselves in augmenter/ejector performance. An unsteady Reynolds averaged Navier–Stokes calculation was used to study the physics of a starting vortex generated at the exit of a pulsed jet and its interaction with an ejector. A 50 cm long pulsejet (typical hobby scale, allowing comparison with experimental data) with a circular exit was modeled as the resonant driving source and used to suggest an optimal ejector geometry and relative position. Computed limit-cycle thrust augmentation values compared favorably to experimentally obtained values for the same ejector geometries. Results suggest that the optimal diameter of the ejector is related to its relative position, dictated by the trajectory of the vortex toroid. The effect of the length of the ejector (which determines the natural frequency of the ejector, related to the acoustic processes occurring in the ejector) on overall performance was also investigated and shown to be less important than the ejector diameter. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JFEGA400013 [...]