The aerodynamics of thin, flat-plate wings of various planforms (rectangular, elliptical and Zimmerman) have been studied in free-to-roll experiments in a wind tunnel. Non-zero trim angles at low angles of attack, selfinduced roll oscillations with increasing angle of attack and even autorotation in some cases were observed. The rectangular wings with round leading-edge had non-zero trim angles at low incidences due to the asymmetric development of the three-dimensional separation bubble at these low Reynolds numbers. With increasing angle of attack, the bubble increases in length and once reattachment is lost, large amplitude roll oscillations develop. The Strouhal number of the roll oscillations is of the order of 10-2, which is in the same range as those expected for small aircraft experiencing atmospheric gusts. Velocity measurements revealed that variations in the strength of the vortices drove the rolling motion. At the mean roll angle, because of the time lag in the strength of the vortices, an asymmetric flow is generated, which results in a net rolling moment in the direction of the rolling motion.


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    Title :

    Low Reynolds number aerodynamics of free-to-roll low aspect ratio wings


    Additional title:

    Aerodynamik Flügeln mit kleinem Seitenverhältnis bei freier Rollbewegung und kleinen Reynolds-Zahlen


    Contributors:

    Published in:

    Experiments in Fluids ; 49 , 1 ; 11-25


    Publication date :

    2010


    Size :

    15 Seiten, 20 Bilder, 1 Tabelle, 22 Quellen




    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English




    Low Reynolds number aerodynamics of low aspect-ratio wings

    Pelletier, Alain / Mueller, Thomas | AIAA | 1999


    Aerodynamics of Free-to-Roll Low Aspect Ratio Wings

    Gresham, N. / Wang, Z. / Gursul, I. et al. | British Library Conference Proceedings | 2009


    Aerodynamics of Free-to-Roll Low Aspect Ratio Wings

    Gresham, Nick / Wang, Zhijin / Gursul, Ismet | AIAA | 2009