A finite-state wake model is used to investigate aeromechanical stability of hingeless-rotor helicopters in the ground-contact, hover and trimmed-flight 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.$
Hingeless-rotor aeromechanical stability in axial and forward flight with wake dynamics
Modellierung der aeromechanischen Stabilität gelenkloser Hubschrauberrotoren unter Berücksichtigung der Dynamik der Nachlaufströmung
Journal of the American Helicopter Society ; 44 , 3 ; 222-233
1999
12 Seiten, 19 Bilder, 21 Quellen
Article (Journal)
English
Aerodynamik , Dämpfungsmessung , Drehbewegung , dynamische Stabilität , Flügelblatt , Frequenzmessung , Hubschrauber , instationäre Strömung , Konvergenz , Korrelationsanalyse , mathematisches Modell , Oberschwingung , Rollen (Drehbewegung) , Rotor (Drehflügel) , Schubkraft , Schwenken (Bewegung) , Schwingungsdämpfung , Wirbelströmung , Nachlaufströmung
Hingeless-Rotor Aeromechanical Stability in Axial and Forward Flight with Wake Dynamics
Online Contents | 1999
|