An experimental investigation of the effects of varying the shroud profile shape on the hovering performance of micro aerial vehicle (MAV)-scale shrouded rotors was conducted, using 17 models with a nominal rotor diameter of 16 cm (6.3 inches) and various values of diffuser expansion angle, diffuser length, inlet lip radius, and blade tip clearance. Compared to the baseline open rotor, the shrouded rotors showed increases in thrust by up to 94 %, at the same power consumption, or reductions in power by up to 62 % at the same thrust. These improvements surpass those predicted by momentum theory, due to the effect of the shrouds in reducing the nonideal power losses of the rotor. Increasing the lip radius and decreasing the blade tip clearance caused performance to improve. The optimal diffuser angle and length were found to be 10 and 50 % of the shroud throat diameter, respectively; further increases in diffuser expansion caused performance to degrade. With the exception of the lip radius, the effects of changing any of the shrouded-rotor parameters on performance became more pronounced as the values of the other parameters were changed to degrade performance. Additional measurements were made of the shroud surface pressure distributions and wake velocity profiles and are presented in a companion paper.


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    Title :

    Hover tests of micro aerial vehicle-scale shrouded rotors. Part I: Performance characteristics


    Additional title:

    Schwebetests von Mikro-Luftfahrzeugen mit ummantelten Rotoren. Teil I: Leistungscharakteristiken


    Contributors:

    Published in:

    Journal of the American Helicopter Society ; 54 , 1 ; 012001/1-012001/28


    Publication date :

    2009


    Size :

    28 Seiten, 19 Bilder, 6 Tabellen, 40 Quellen




    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English