Using Multibody Dynamics for the Stability Assessment of a New Rotor Test Rig

Abstract

The secure entry into service of a new rotor test rig requires the assessment of the dynamic and aeroelastic rotor stability. To this end, a multibody dynamics based numerical model was developed and coupled with an unsteady aerodynamic model based on Wagner's function and related enhancements for the general motion of an airfoil section considering heave and pitch motion. The simulation model uses modelling techniques for the setup of a linearized model and allows both, the investigation of ground resonance and flutter for the rig with clamped and articulated rotor blades in frequency domain. With respect to ground resonance, the dynamic examination of the two- and four-bladed rotor configurations shows a mechanically stable behaviour for the clamped and articulated rotor blades with lead-lag hinge in the planned rotor speed range up to 65 Hz. The aeroelastic assessment shows a damped behaviour for the configurations with clamped rotor blades, whilst the articulated rotor with lead-lag hinge is unstable beyond rotational speeds of 25 Hz for the two-bladed rotor and requires additional damping measures.