Active aeroelastic control of supersonic transport aircraft

This dissertation describes the aeroservoelastic modeling and active control of a supersonic transport aircraft configuration.;Aeroelastic models are developed based on reduced order models of structural dynamics and unsteady aerodynamics. Structural dynamic models are generated based on the modal solution of a finite element model. Unsteady aerodynamic models are generated using potential flow, Euler, and Navier Stokes methods at a variety of flight conditions. The structural and aerodynamic models are combined with state space representations of actuators and gust excitation to form coupled aeroservoelastic system models. These models are reduced using balanced realizations, and using a new method of generating reduced order models that can be interpolated across flight conditions. Analytical results are compared with structural dynamic, aerodynamic, and aeroelastic experimental results. Analytical models are tuned to match experimentally measured modal frequencies. Results demonstrating good correlation are noted, effects that are not adequately simulated are cited for results demonstrating poor correlation.;Control laws are designed for the aeroelastic plant models using the linear quadratic Gaussian approach with loop transfer recovery. Various control laws are developed by changing design weighting parameters, design dynamic pressure, and input and output utilization Additional variation is introduced by choosing the order of plant model reduction and inclusion of bandpass filters into the controller. The robustness and performance of the resulting controllers are evaluated analytically. These analytical studies demonstrate a significant increase in the flutter dynamic pressure for the closed loop system relative to the open loop flutter boundary. Three SISO controllers and one MIMO controller are selected for closed loop testing.;Results from closed loop testing of selected controllers are presented. The selected SISO controllers are shown to reduce vibration, increase modal frequency spacing, and decrease the tendency of mode shapes to converge at relatively high dynamic pressure. This behavior is demonstrated in the subsonic, transonic, and supersonic regimes. The selected MIMO controller does not exhibit these desirable characteristics in the resulting closed loop system.