Prediction of lag damping is difficult owing to the delicate balance of drag, induced drag and Coriolis forces in the in-plane direction. Moreover, induced drag is sensitive to dynamic wake, both shed and trailing components, and thus its prediction requires adequate unsteady-wake representation. Accordingly, rigid-blade flap-lag equations are coupled with a three-dimensional finite-state wake model; three isolated rotor configurations with three, four and five blades are treated over a range of thrust levels, Lock numbers, lag frequencies and advance ratios. The investigation includes convergence characteristics of damping with respect to the number of radial shape functions and harmonics of the wake model for multiblade modes of low frequency (less than 1/rev.) to high frequency (greater than 1/rev.). Predicted flap and lag damping levels are then compared with similar predictions with (1) rigid wake (no unsteady induced flow, (2) Loewy lift defficiency and (3) dynamic inflow. The coverage also includes correlations with the measured lag regressive-mode damping in hover and forward flight and comparisons with similar correlations with dynamic wake model are consistently higher than the predictions with the dynamic inflow model; even for the low frequency lag regressive mode, the number of wake harmonics should at least be equal to twice the number of blades.


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    Titel :

    Flap-lag damping in hover and forward flight with a three-dimensional wake


    Beteiligte:
    Manjunath, A. R. (Autor:in) / Nagabhushanam, J. (Autor:in) / Gaonkar, Gopal H. (Autor:in) / Peters, David A. (Autor:in) / Su, AY (Autor:in)


    Erscheinungsdatum :

    01.10.1993



    Medientyp :

    Sonstige


    Format :

    Keine Angabe


    Sprache :

    Englisch


    Schlagwörter :


    Flap-lag damping in hover and forward flight with a three-dimensional wake

    Manjunath, A.R. / Nagabhushanam, J. / Gaonkar, G.H. et al. | Tema Archiv | 1993



    Flap-lag-torsion stability in hover and forward flight with three-dimensional wake

    Manjunath, A. R. / Chunduru, S. J. / Nagabhushanam, J. et al. | AIAA | 1996


    Flap-Lag-Torsion Stability in Hover and in Forward Flight With a Three-Dimensional Wake

    Manjunath, A. R. / Nagabhushanam, J. / Gaonkar, G. H. et al. | British Library Conference Proceedings | 1994


    Flap-Lag-Torsion Stability in Hover and in Forward Flight With a Three-Dimensional Wake

    Manjunath, A. R. / Nagabhushanam, J. / Gaonkar, G. H. et al. | British Library Conference Proceedings | 1993