Coaxial rotor aeroelasticity is complex due to the counter-rotating wake system, rotor lift offset, periodic blade passage loads, unsteady rotor wake interactions, reduced rotor speed, and stiff hingeless blades. In this study, the aeroelastic stability of a coaxial rotor is examined in hover and forward flight. The rotor wake is modeled with the viscous vortex particle method, a grid-free approach for calculating vortex interactions over long distances. The spanwise blade aerodynamic loading is calculated using a computational-fluid-dynamics-based reduced-order model in attached flow, and the ONERA dynamic stall model in separated flow. Two propulsive trim procedures are developed: one with the propulsor not operating, and the other with the vehicle at level attitude. An aeroelastic stability analysis based on Floquet theory is applied to the periodic system. A novel graphical method is developed to identify coupling between blade modes of the two rotors. The effects of lift offset and advance ratio on the hub loads, inflow distribution, and aeroelastic stability are examined to provide an improved physical understanding of the aeroelastic interactions. Results indicate that the blade passage effect is caused by the bound-circulation-induced inflow. The first and second lag modes are the least stable modes in hover and forward flight.

由于反向旋转尾流系统、转子升力偏移、周期性叶片通过载荷、不稳定的转子尾流相互作用、降低的转子速度和刚性无铰链叶片，同轴转子气动弹性是复杂的。在这项研究中，同轴旋翼在悬停和前飞中的气动弹性稳定性得到了检验。转子尾流使用粘性涡流粒子方法建模，这是一种用于计算长距离涡流相互作用的无网格方法。在附着流中使用基于计算流体动力学的降阶模型和在分离流中使用 ONERA 动态失速模型计算展向叶片气动载荷。开发了两种推进配平程序：一种是推进器不工作，另一种是车辆处于水平姿态。基于 Floquet 理论的气动弹性稳定性分析应用于周期系统。开发了一种新颖的图形方法来识别两个转子的叶片模式之间的耦合。检查升力偏移和推进比对轮毂载荷、流入分布和气动弹性稳定性的影响，以提供对气动弹性相互作用的更好的物理理解。结果表明，叶片通道效应是由约束环流引起的流入引起的。第一和第二滞后模式是悬停和前飞中最不稳定的模式。和气动弹性稳定性进行了检查，以提供对气动弹性相互作用的更好的物理理解。结果表明，叶片通道效应是由约束环流引起的流入引起的。第一和第二滞后模式是悬停和前飞中最不稳定的模式。和气动弹性稳定性进行了检查，以提供对气动弹性相互作用的更好的物理理解。结果表明，叶片通道效应是由约束环流引起的流入引起的。第一和第二滞后模式是悬停和前飞中最不稳定的模式。