An experimental and computational investigation of a combination of fluidic injection and chevrons (fluidically enhanced chevrons) for supersonic jet noise reduction was performed. Previous studies have shown that chevrons underperform in overexpanded flow due to reductions in effective penetration. Consequently, this study focuses on improvements gained by fluidic enhancement in the overexpanded regime. Acoustic results indicated the fluidically enhanced chevrons outperform the chevrons, with additional overall sound pressure level reductions of 2 dB in the upstream direction and nearly 1.5 dB in the downstream direction. Spectral results indicated that primary benefits were in shock and low-frequency noise. A small high-frequency penalty was the only observed detriment. Time-averaged velocity and turbulence quantities as well as shock cell spacing, were computed by large-eddy simulation and then compared to particle imaging velocimetry and shadowgraph results. These flowfield measurements indicated that the fluidically enhanced chevrons modify the flowfield by reducing the shock cell spacing and shock strength and increasing the upstream jet half-width, peak and integrated turbulence values, and shear-layer thickness. These modifications were caused by the introduction of streamwise vortices with over four times the magnitude of the unenhanced chevrons. Noise reductions were attributed to flowfield modifications through the use of several theoretical models, such as Powell’s screech formula.


    Zugriff

    Zugriff prüfen

    Verfügbarkeit in meiner Bibliothek prüfen

    Bestellung bei Subito €


    Exportieren, teilen und zitieren



    Titel :

    Fluidically Enhanced Chevrons for Supersonic Jet Noise Reduction


    Beteiligte:
    Heeb, N. (Autor:in) / Gutmark, E. (Autor:in) / Liu, J. (Autor:in) / Kailasanath, K. (Autor:in)

    Erschienen in:

    AIAA Journal ; 52 , 4 ; 799-809


    Erscheinungsdatum :

    2014-03-06


    Format / Umfang :

    11 pages




    Medientyp :

    Aufsatz (Zeitschrift)


    Format :

    Elektronische Ressource


    Sprache :

    Englisch





    Supersonic Jet Noise Reduction by Chevrons Enhanced with Fluidic Injection

    Heeb, Nick / Munday, David / Gutmark, Ephram et al. | AIAA | 2010


    Numerical Investigation of Fluidic Enhanced Chevrons for Noise Reduction in Supersonic Jets

    Liu, J. / Kailasanath, K. / Ramammurti, R. et al. | British Library Conference Proceedings | 2012


    Numerical Investigation of Fluidic Enhanced Chevrons for Noise Reduction in Supersonic Jets

    Liu, Junhui / Kailasanath, Kailas / Ramammurti, Ravi et al. | AIAA | 2012


    An MDOE Investigation of Chevrons for Supersonic Jet Noise Reduction

    Henderson, Brenda / Bridges, James | AIAA | 2010