Reduced Order Model For Unsteady Aerodynamics And Its Application

With the development of material technology, information technology, automation control technology, aeronautics and astronautics technology, the modern flight vehicles are required of high velocity, light structure, great flexibility and super maneuverability, which lead to the serious aeroelastic effects such as aeroservoelasticity, the coupling among the aerodynamics, structure, and control system. Flutter is the most important instable problem and it restricts the flight envelope and performance of a vehicle. Aeroservoelasticity, including active flutter suppression technology, is a multidisciplinary optimization technology that studies the interaction of flexible structure, unsteady aerodynamics and flight control system.When it comes to the aeroservoealstic analysis and design, the first problem is to construct a reduced order model, convenient to the design of active control system. The conventional model construction method, rational functional approximation method, can't describe the nonlinear effect of the nonlinear unsteady aerodynamics. So the reduced order model based on Volterra series for linear and nonlinear unsteady aerodynamics was investigated and applied to the model construction and active control law design of aeroelastic system. The work was as follows:1. Investigated the basic theory of the coupled CFD/CSD simulation of nonlinear unsteady aerodynamics and prepared basic data for reduced order model.2. Investigated the reduced order model for nonlinear unsteady aerodynamics based on Volterra series, especially the identification method of the Volterra kernels and studied the application domain and accuracy of the model.3. Investigated the direct model construction method of unsteady aerodynamics state space equation from Volterra kernels, including linear state space model and bilinear state space model. The general model construction method for ASE was brought forward.4. Designed active control law for a two dimensioned PAPA system based on the dynamic differential coefficient derivative model and ROM put forward in this paper, and investigated some practical issues in application.The main innovations in this paper are as follows:1. Integrated ASE design and coupled CFD/CSD simulation technology and firstly applied the reduced order model based on Volterra series to the design of ASE system2. Based on linear state space model, put forward two elementary practical methods of constructing bilinear state space model for nonlinear unsteady aerodynamics with contribution to nonlinear ASE technology.