The mixing of the two flows reduces the velocity of the jet within the ejector shroud, while increasing the existing mass flux. By efficiently increasing the mass flow rate through the ejector an increase in thrust can be attained, provided that the resultant decrease in velocity is minimized. Although ejector designs have varied greatly in size and aspect ratios, general conclusions can be made for all ejectors. Most of the past literature on ejector designs has shown that the mixing of the inlet streams is the determining factor in the performance of a steady flow ejector. Mixing designs using large-scale, low-loss, streamwise vorticity have been proven to be most effective. Although the mixing within the ejector is most critical, its design must be compact and lightweight in order to be practical. For these reasons this study focuses on increasing the mass entrainment of small, low-aspect-ratio ejectors. The addition of large-scale streamwise vortices at the nozzle exit increases centerline velocity decay, mass entrainment, and shear layer spreading within a simple circular ejector. The 90-deg symmetric configuration of half-delta-wing vortex generators used in this study produces a set of four corotating vortices that enhaces mixing within the ejector. The initial centerline velocity decay in the vortex case is only weakly dependant on ejector parameters, implying that the streamwise vorticity dominates within the first five diameters of the nozzle exit. The results presented on the mass entrainment of the vortex ejector show more than a 40 % increase in mass entrainment due to the presence of the vortices. Although the vortex cases always showed an improvement over the reference cases, the most attractive feature is that they show the greatest improvement for the more compact ejector configurations. Thus, the use of vortex generators would be especially beneficial for smaller and shorter ejectors which are typically preferred for practical considerations. This study, to date, has only examined the increase in thrust.


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    Titel :

    Use of streamwise vorticity to increase mass entrainment in a cylindrical ejector


    Weitere Titelangaben:

    Anwendung der Wirbelfadenbildung zur Vergrößerung der Eintrittsmassen in eine zylindrische Düse


    Beteiligte:
    Carletti, M.J. (Autor:in) / Rogers, C.B. (Autor:in) / Parekh, D.E. (Autor:in)

    Erschienen in:

    AIAA Journal ; 33 , 9 ; 1641-1645


    Erscheinungsdatum :

    1995


    Format / Umfang :

    5 Seiten, 12 Bilder, 1 Tabelle, 20 Quellen




    Medientyp :

    Aufsatz (Zeitschrift)


    Format :

    Print


    Sprache :

    Englisch