Predictions and measurements of stability, control angles and loads for an isolated hingeless rotor are presented to illustrate the effects of aerodynamic modeling. The test model has four soft-inplane, soft-torsion blades and was tested at a realistic tip speed in the range of existing flight vehicles. Key measurements in the database include the cyclic pitch controls, steady root-flap moment and regressive lag-mode damping for two coning angles with advance ratio, shaft angle and collective pitch variations. A modal approach with both nonrotating and rotating modes, the ONERA dynamic stall models of lift, drag and pitching moment, and a three-dimensional finite-state wake model are used. The cyclic pitch controls and the corresponding periodic responses are predicted by the periodic shooting method with damped Newton iteration; this method is based on the fast-Floquet theory and generates the equivalent Floquet transition matrix (EFTM) as a by-product. The eigenvalues and eigenvectors of the EFTM provide the frequencies and damping levels. The steady root-flap moment is calculated by both the force-integration and mode-deflection methods. A major finding is that including a finite-state wake model dramatically improves the prediction of the lateral cyclic pitch control.
Correlation of several aerodynamic models and measurements of hingeless-rotor trim and stability
Journal of the American Helicopter Society ; 45 , 2 ; 106-117
2000
12 Seiten, 12 Bilder, 8 Tabellen, 20 Quellen
Aufsatz (Zeitschrift)
Englisch
Abreißen der Strömung , Biegemoment , Biegeschwingung , dynamischer Auftrieb , Eigenwertproblem , Integralgleichung , mathematisches Modell , Matrix (Zahlenschema) , Neigungswinkel , Rotor (Drehflügel) , Schwingungsanalyse , Schwingungsanregung , Schwingungsdämpfung , Steuerung , Strömungswiderstand , Theorie-Experiment-Vergleich , Trimmen , Versuchsmodell
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