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A comparison of coaxial and conventional rotor performance

Kim, Hyo Wan and Brown, R.E. (2009) A comparison of coaxial and conventional rotor performance. Journal of the American Helicopter Society, 55 (1). 012004-1. ISSN 0002-8711

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    Abstract

    The performance of a coaxial rotor in hover, in steady forward flight, and in level, coordinated turns is contrasted with that of an equivalent, conventional rotor with the same overall solidity, number of blades, and blade aerodynamic properties. Brown's vorticity transport model is used to calculate the profile, induced, and parasite contributions to the overall power consumed by the two systems, and the highly resolved representation of the rotor wake that is produced by the model is used to relate the observed differences in the performance of the two systems to the structures of their respective wakes. In all flight conditions, all else being equal, the coaxial system requires less induced power than the conventional system. In hover, the conventional rotor consumes increasingly more induced power than the coaxial rotor as thrust is increased. In forward flight, the relative advantage of the coaxial configuration is particularly evident at pretransitional advance ratios. In turning flight, the benefits of the coaxial rotor are seen at all load factors. The beneficial properties of the coaxial rotor in forward flight and maneuver, as far as induced power is concerned, are a subtle effect of rotor-wake interaction and result principally from differences between the two types of rotor in the character and strength of the localized interaction between the developing supervortices and the highly loaded blade-tips at the lateral extremities of the rotor. In hover, the increased axial convection rate of the tip vortices appears to result in a favorable redistribution of the loading slightly inboard of the tip of the upper rotor of the coaxial system.

    Item type: Article
    ID code: 27336
    Keywords: coaxial rotor performance, conventional rotor performance, rotor–wake interaction, Mechanical engineering and machinery, Motor vehicles. Aeronautics. Astronautics, Mechanical Engineering, Aerospace Engineering, Modelling and Simulation
    Subjects: Technology > Mechanical engineering and machinery
    Technology > Motor vehicles. Aeronautics. Astronautics
    Department: Faculty of Engineering > Mechanical and Aerospace Engineering
    Related URLs:
      Depositing user: Ms Katrina May
      Date Deposited: 02 Sep 2010 13:32
      Last modified: 02 Jun 2014 20:12
      URI: http://strathprints.strath.ac.uk/id/eprint/27336

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