Numerical simulation of nonlinear aero-servo-elasticity in time domain

By using unsteady aerodynamic solver, the unsteady loads of control surface can be solved directly in time domain. The transfer function of the servo system in Laplace domain is transformed to time domain to produce the servo state equations. By solving the time domain aerodynamic equations, structure state equations and servo state equations in every time step, the aeroservoelastic problem can be simulated in time domain. It can solve the aeroservoelastic problem with aerodynamic nonlinearity easily, such as transonic, high angles of attack and hypersonic problem. By numerical simulation, the servo system can greatly reduce the aeroelastic stability. The structural filter added to the system can reduce the coupling effect of servo system and structure mode and increase the critical flutter velocity. We give the examples of the LCO responses at high angle of attack and the nonlinear characteristic of the aeroservoelastic velocity changing with the increasing angle of attack at Mach number 7.