Prediction of Tiltrotor Vibratory Loads with Inclusion of Wing­-Proprotor Aerodynamic Interaction

A numerical methodology for the prediction of vibratory loads arising in wing–proprotor systems is presented. It is applicable to tiltrotor operating conditions ranging from airplane to helicopter-mode flights. The aeroelastic formulation applied takes into account the aerodynamic interaction effects dominated by the impact between proprotor wake and wing, along with the mutual mechanical influence between elastic wing and proprotor blades. A boundary integral formulation suited for configurations where strong body–vortex interactions occur yields the aerodynamic loads, and beamlike models are used to describe the structural dynamics. A harmonic balance approach is applied to determine the aeroelastic solution. In the numerical investigation, first, the aerodynamic solver is validated by correlation with experimental and numerical results available in the literature, then the vibratory loads transmitted by the wing–proprotor system to the airframe are predicted, focusing the attention on the analysis of the different aerodynamic contributions.