Gust Load Analysis And Alleviation For An Elastic Aircraft

In flight, aircrafts suffer atmospheric turbulence and the flight quality degrades. The additional dynamic loads caused by the gust will shorten the fatigue life of the structure, which will have influence on the flight safety. In order to reduce the impact of the gust on the structural strength and improve the performance of aircrafts, gust load alleviation is one of the most effective techniques.In recent years, the accuracy of the gust information in front of the aircraft detected by airborne lidar is increasing, which makes it possible for designing the gust load alleviation systems based on the forward looking gust information. In this thesis, the gust response of a civil aircraft is studied by means of establishing an aeroservoelastic model including structure dynamics and unsteady aerodynamics. In order to design an efficient gust load alleviation system that respects the actuation constraints of the control surfaces, uses preview information on the incoming gust shape from a Light Detection And Ranging gust sensor, model predictive control(MPC) strategy is applied to an aeroservoelastic aircraft model. The ailerons and elevators are used as control surface to alleviate the wing root shearing force, bending moment as well as the acceleration response at wing tip etc. The simulation results for the closed loop system are compared with those obtained by the reference controller(PID). It has been shown that the controller with MPC law can suppress the gust loads effectively, meanwhile, the deflection of the control surface can satisfy the hard constrain.