The aeroelastic responses and stability of hingeless rotor blades in hover were investigated using both the refined the structural and aerodynamic models with compressibility correction. Finite elements based on a large deflection-type beam theory are used for the structural analysis. Although the strain components in the beam element are assumed to be small compared to unity, no kinematical limitations are imposed on the magnitude of displacements and rotations. Three-dimensional aerodynamic model, based on the unsteady vortex lattice method with a prescribed wake geometry, can predict the unsteady aerodynamic loads of the multi-bladed rotors and the effect of the interblade unsteady wake dynamics beneath the rotor blades on the aeroelastic response. Numerical results of the steady-state deflections and the stability for the stiff inplane rotor blade are presented. It is found that the three-dimensional aerodynamic tip- relief and unsteady wake dynamics effects play an important role in the hingeless rotor aeroelastic analysis in hover.
The blade speed is high enough so that the well-established incompressible flow techniques may give inaccurate results. Thus compressibility effect must be taken into account. In this study, for the rapid estimation of compressible aerodynamic forces and pressure distributions, compressibility correction factor was used. The compressibility effect significantly influences aeroelastic response and increases the stability of the multi-bladed hingeless rotors in hover.