Amplitude-Dependent Analysis of Interactional Aerodynamic Effects on Wing–Propeller Aeroelastic Stability

This paper investigates the influence of interactional aerodynamic effects on the aeroelastic stability of a wing–propeller configuration. The configuration is modeled in the Rotorcraft Comprehensive Analysis System using lifting-line aerodynamics coupled with uniform inflow and the viscous vortex particle method as the wake models for the wing and propeller, respectively. The local damping and frequency characteristics are estimated using an output-based method that captures amplitude effects arising from system nonlinearity. This amplitude-dependent analysis considers different levels of wing–propeller aerodynamic interaction, excitation amplitudes, and pylon lengths, with and without wing flexibility. At lower forward speeds, the local damping decreases with increasing propeller hub displacements, with and without aerodynamic interactions; the local frequency decreases slightly with increasing hub displacements across all speeds. Amplitude effects weaken at higher forward speeds due to faster downstream convection of the propeller wake, resulting in approximately linear behavior near instability. The influence of wing–propeller aerodynamic interactions on local damping decreases with larger hub displacements, a behavior attributed to the skewness of the propeller wake and its wash over the wing. This work provides new insights into the influence of propeller wakes and interactional aerodynamics on the aeroelastic stability of wing–propeller systems and highlights the limitations of conventional linear analysis methods.