Hingeless-rotor aeromechanical stability in axial and forward flight with wake dynamics

Nagabhushanam, J and Gaonkar, GH (1999) Hingeless-rotor aeromechanical stability in axial and forward flight with wake dynamics. In: Journal of The American Helicopter Society, 44 (3). pp. 222-233.

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Abstract

A finite-state wake model is used to investigate aeromechanical stability of hingeless-rotor helicopters in the ground-contact, hover and trimmed-night conditions. The investigation covers three items: (1) the convergence of the damping with increasing number of wake harmonics for the lag regressing, and body pitch and roll modes; (2) a parametric study of the damping over a range of thrust level, advance ratio and number of blades; and (3) correlations, primarily with the damping and frequency measurements of these lag and body modes. The convergence and parametric studies are conducted in the hover and trimmed-flight conditions; they include predictions from the widely used dynamic inflow model. The correlations are conducted in the ground-contact conditions and include predictions from the dynamic inflow and vortex models; recently, this vortex model is proposed for the axial-flight conditions and is used to investigate the coupled free vibrations of rotor flapping and body modes. The convergence and parametric studies show that a finite-state wake model that goes well beyond the dynamic inflow model is required for fairly converged damping, Moreover, the correlations from the finite-state wake, dynamic inflow and vortex models are generally satisfactory.

Item Type:	Journal Article
Publication:	Journal of The American Helicopter Society
Publisher:	American Institute of Aeronautics and Astronautics.
Additional Information:	Copyright of this article belongs to American Institute of Aeronautics and Astronautics.
Department/Centre:	Division of Mechanical Sciences > Aerospace Engineering(Formerly Aeronautical Engineering)
Date Deposited:	12 Aug 2009 08:18
Last Modified:	19 Sep 2010 05:29
URI:	http://eprints.iisc.ac.in/id/eprint/19622

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