The objective of this work is to study the flutter characteristics of an airfoil in a two-dimensional subsonic flow by externally coupling a Reynolds Average Navier Stokes (RANS) based CFD solver with the in-house structural code in time domain. The ANSYS FLOTRAN CFD, a finite element based computational fluid dynamics solver, is adopted here to generate the aerodynamic pressure distributions on an airfoil section in subsonic regime. The airfoil dynamics is accordingly simulated through external coupling of the ANSYS FLOTRAN CFD solver with a 2DOF airfoil structural model through a Newmarks’s implicit time integration scheme. A symmetric NACA 0012 airfoil of unit chord is chosen for the analysis, with suitable springudstiffness and inertia values so that flutter instability occurs in the subsonic regime. Unsteady motion in the fluid-structure system is numerically simulated with small initial conditions. In the present analysis, the airfoil is not allowed to move and the pitch angle of airfoil is assigned to the air flow at the inlet boundary of the domain. Flutter boundary is indicated by the critical freeudstream flow velocity (and dynamic pressure) beyond which oscillation amplitudes diverge in time.
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