In this paper, three morphing concepts, namely TED, LED, and active twist, are investigated for the rotor aerodynamic performance improvements. This investigation is a simulation-based trade study and is conducted using a combination of lifting-line comprehensive analysis and coupling of CFD and CSD. A novel NURBS-based airfoil surface parameterization is integrated into the CFD module to realize dynamic blade morphing involving TED and LED and is shown to work efficiently. Blade morphing of a full-scale UH-60A Blackhawk rotor is studied at two key flight conditions: high-speed forward flight and high-thrust forward flight. For each of the morphing concepts, harmonic deployment schedules are tested followed by a sensitivity study. All three morphing concepts demonstrated improvements in rotor performance. The following are the key conclusions of this study: 1) TED and active-twist concepts improve performance by generating additional lift, but without drag penalty in the advancing side negative tip loading regions. The additional lift is generated in the advancing side due to an increase in the blade AOA. The increase in AOA results from the pitch-up moments that are induced by upward TED, and in the case of active twist direct change in blade pitch. Therefore, these concepts work well for high-speed flight with large negative tip loading but do not work well for high-thrust flight where the additional lift is accompanied by a simultaneous drag increase; 2) Performance gains obtained using lower harmonic (steady, 1, and 2/rev) deployment appear to be equal to or greater than those obtained using higher harmonics (3/rev and 4/rev); 3) The LED concept improves performance by mitigating retreating side dynamic stall. This concept is, therefore, well suited for high-thrust conditions, where significant stall regions exist, and in such cases, it can produce large L/De and power improvementson the order of 15 %; 4) For the high-speed forward flight condition, comparison between lifting-line analysis and coupled CFD-CSD analysis shows that both produce mutually consistent performance gains. However, for the highthrust forward flight (C9017) the difference is significant between the two. This is due to the lack of dynamic stall models for morphing airfoils. A future study could involve a formal closed-loop optimization employing lifting-line calculations to identify optimal points and then CFD-CSD analysis for detailed evaluation of the down selected optimal points.


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    Titel :

    Computational fluid dynamics-computational structural dynamics analysis of active control of helicopter rotor for performance improvement


    Weitere Titelangaben:

    Gekoppelte, instationäre numerische Analyse der Fluid-Struktur-Wechselwirkung bei einem Hubschrauberrotor zur Leistungssteigerung bei aktiver Regelung


    Beteiligte:
    Jain, Rohit (Autor:in) / Yeo, Hyeonsoo (Autor:in) / Chopra, Inderjit (Autor:in)

    Erschienen in:

    Journal of the American Helicopter Society ; 55 , 4 ; 042004/1-042004/14


    Erscheinungsdatum :

    2010


    Format / Umfang :

    14 Seiten, 19 Bilder, 2 Tabellen, 35 Quellen




    Medientyp :

    Aufsatz (Zeitschrift)


    Format :

    Print


    Sprache :

    Englisch