Transonic aeroelastic analysis basing on reduced order aerodynamic models

Reduced order modeling (ROM) is a conceptually novel and computationally efficient technique for unsteady aerodynamics computation. Using input-output difference model and least squares method, ROM of unsteady aerodynamic loads based on unsteady Euler codes is constructed. The input-output difference model is then turned into continuous-time model in state space. Coupled structural state equations and aerodynamic state equations, state equations of transonic aeroelastic system are constructed. By solving the eigenvalues of the state matrix at a series of dynamic pressure, the aeroelastic stability is analyzed with the roots loci map. The ROM based results agree with those by solving CFD/CSD directly coupling method. It proves that this method is available to solve the transonic aeroelasticity. An interesting S-type flutter boundary which due to the system having more than one neutral point at the transonic Mach number range is analyzed particularity. It is just because the flutter branch changes with the increasing speed (dynamic pressure).