Aerodynamic Model of a Helicopter Rotating Rotor Blade
The aim of the present investigation is the dynamics of a rotating flexible mechanism composed of a helicopter main flexible rotor blade. In previous works of Crellin and Janssens (1983), Hablani (1982), Hughes (1974), Sylla and Barou (2008), Sylla and al(2008) neglecting the aerodynamic forces. The blade small elastic vibrations interacting with the standing rotor rotation motions are described by Rayleigh-Ritz continuum approach using the cantilever modes. In the present paper, one considers a stationary flight of the helicopter subjected to aerodynamic forces. The differential equations of the flexible blades vibrations show the interaction between the aerodynamic forces and these vibrations. The modal analysis of motions equations using Rayleigh-Ritz discretisation method leads to the blade impedance matrix spectral expansion. This matrix enables us to calculate the blade global frequencies in terms of the aerodynamic parameters.
Keywords: Impedance matrix, cantilever modes, global frequencies, aerodynamic forces.