Significant progress has been made in aeroelastic analysis of an isolated airfoil, mostly under the assumption of a steady freestream. In reality, however, the inflowing freestream is often pulsating. Therefore, this paper presents a stability analysis of an isolated airfoil under pulsating freestream conditions and a forced response analysis of an isolated rotor blade rotating at a constant angular velocity. First, a new unsteady vortex lattice model with an unsteady freestream flow has been developed in discrete time domain to examine unsteady aerodynamic forces acting on a vibrating airfoil. Second, the airfoil's aeroelastic behavior has been analyzed using a typical section method. The 2-D analysis requires a structural dynamic solution coupled with aerodynamic calculation. In the aeroelastic analysis, the flutter onset of an airfoil under pulsating freestream is predicted using Floquet analysis. Finally, the forced response of a rotating airfoil due to a combination of a time-varying angle of attack and a time-varying freestream has been examined.
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