Analytic solution of in-plane vortex–rotor interactions with arbitrary orientation and its impact on rotor trim

The general aerodynamic problem of arbitrarily oriented in-plane vortex-rotor interaction was investigated in the past only by numerical simulation. Just one special case of in-plane vortex-rotor interaction with the vortex axis in flight direction was recently solved analytically. In this article, the analytical solution for arbitrary in-plane vortex orientation and position relative to the rotor is given for the first time. The solution of the integrals involved as derived here encompasses and simplifies the previous derivation of the special case significantly. Results provide the vortex impact on rotor trim (thrust, aerodynamic rolling and pitching moments about the hub) and the rotor controls required to mitigate these disturbances. For the special case with the vortex axis in flight direction, the results are identical to the former solution and results for the other in-plane vortex orientations and positions agree with the numerical results obtained so far.

Multibody simulation of a generalized predictive controller for tiltrotor active aeroelastic control

A generalized predictive control has been developed for the control of the aeroelasticity and structural dynamics of a tiltrotor. Adaptivity is the key feature of the proposed technique. It gives the controller the capability to autonomously follow the variations of the system. A comprehensive simulation system has been adopted to design and test the adaptive regulator under realistic conditions. The aeroservoelastic tiltrotor has been modelled using a multibody approach, considering the structural dynamics, the aerodynamics, the blade pitch control system kinematics, and actuator and sensor dynamics. Numerical simulations illustrate the capability of the adaptive controller to reduce wing vibrations and loads while significantly extending the flutter-free flight envelope. This controller shows satisfactory performances within the whole flight envelope as it is able to properly work in different rotor trim conditions and varying structural properties in the presence of external disturbances and measurement noise.