Effects of Freestream Flow on Time Delays and Dynamics in Coaxial Rotor Systems

View Video Presentation: https://doi.org/10.2514/6.2021-1829.vid The effect of freestream flow on coaxial rotor dynamics is investigated with finite-state inflow methods. The finite-state inflow for coaxial rotors contain terms with time delays that are driven by the rotor spacing and freestream velocity. The work presented here focuses on how variations in freestream velocity impact the on-disk velocity profiles and blade flapping dynamics at select rotor spacings due to the time delay. These variations are related to adjustments to pitch angles, coupling matrices, and the time-delayed terms themselves. When the time delays are held constant, the variations in rotor spacing and freestream velocity impact the magnitude of shed vortices and the effect that they have on the dynamics of the velocity on the lower rotor.