Research Information System
49th European Rotor Craft Forum, Bonn, Germany, 5 - 07 September 2023, vol.1, no.2023, pp.1-17, (Full Text)
This paper presents a methodology that identifies a state-space rotor inflow model for a 1.5-m radius two bladed eVTOL rotor in descent. Main purpose of the work is to identify a state-space model for an isolated rotor for all descent envelope especially in vortex ring state condition by mid-fidelity aeromechanics analysis framework. Mid-fidelity simulation framework includes Viscous Vortex Particle Method (VVPM) accelerated by GPU coupled with a Generic Air Vehicle Model (GAVM) which is a mathematical model for analysis of generic configurations such as propeller aircrafts, conventional and unconventional rotorcrafts, multi-rotor and tiltrotor eVTOL configurations. Vortex ring state (VRS) envelopes are investigated by VVPM for full combination of several descent rates, forward velocities, collective pitch and rotational speed. VRS envelopes are visualized in terms of level of thrust and oscillatory loads to determine the critical flight conditions in terms of flight control. Instabilities, and rotor performance are discussed in detail. System identification of an isolated rotor is performed by VVPM simulations for collective frequency sweeps. Rotor performance in steep descent, system identification results, nonlinearities, unsteady aerodynamics and modeling methodologies are discussed in detail.