Unsteady Aerodynamics And Aeroelastic Analysis Based On Volterra-Series

Modern aircraft is required of high velocity, light structure, great flexibility, and super maneuverability, which lead to strong interactions between the flexible structure and the surrounding flow. Consequently aircraft suffers serious aeroelastic problems. These interactions are nonlinear and need analysis methods that are capable of addressing such nonlinear phenomena for proper understanding. With the development of powerful digital computers, aeroelastic response can be more accurately predicted using coupled computational fluid dynamic (CFD)/computational structure dynamic (CSD) numerical simulation. However, the simulation remains too computationally expensive to be used in multi-disciplinary settings and the aeroelastic analysis of complicated systems. Furthermore, while the simulation can provide detailed time histories of discretized field variables, such data may not readily imbue the investigator with an increased level of understanding concerning the physics essential to a given phenomenon. Therefore it is necessary to construct an aeroelastic reduced-order model (ROM) which rapidly provides accurate descriptions of the dynamics and is convenient for active control system design.In order to meet the demand of aeroservoelastic analysis and synthesis, a ROM based on Volterra series for nonlinear unsteady aerodynamics is investigated. The process is that the approximate first-order Volterra kernels are identified from the step responses of generalized unsteady aerodynamics which is calculated by CFD/CSD; the Volterra-kernels-based state-space ROM of unsteady aerodynamics is built using eigensystem realization algorithm (ERA). Then the aeroelatic state-space model is acquired by coupling unsteady aerodynamics ROM with linearized structure dynamic equation.To demonstrate the method, the reduced-order model is implemented on AGARD 445.6 wing which is a standard aeroelastic configuration. The prediction of unsteady aerodynamics and analysis of aeroelastic dynamic response/stability are conducted relatively using the aerodynamics and aeroelastic ROM, which compared with the data of CFD/CSD numerical simulation. The results indicate that the method is rapid and accurate in solving aeroelastic problems.