COMPUTER SIMULATION OF FLUTTER ELEMENTS OF A SYMMETRIC AIRFOIL USING THE VIRTUAL BOUNDARY METHOD FOR FLUID-STRUCTURE INTERACTION.

Abstract. The objective of the present work is an numerical analysis of flutter elements of a typical airfoil using a classical method with direct eigenvalue method for the undamped case (forced oscillation). The dynamic coupling of the airfoil structure into two-dimensional aerodynamic flow was simulated with ultra-low Reynolds number so that the aeroelastic mo-tion of the airfoil in the flow could have simulated in the time domain. The intention was to determine the flutter elements in the small wings (like a Micro air vehicle), using a two-dimensional aerodynamic code based on Virtual Boundary Method, suitably coupled to the airfoil structural characteristics. The symmetric NACA 0012 airfoil was choosed to simulate the time history of flow parameters. The airfoil was considered as a rigid section, supported by translational and rotational springs, so that only heave and pitch degrees of freedom are permitted at the point of support. The pitching and heaving movements where simulated sep-arately. The effects of forced oscillation were analyzed an attack angle of 0o for heaving, and vertical oscillation of ±0.1 of chord length; pitching of ±2o with frequency (sinusoidal), f s of 1Hz, 2Hz, 5Hz and 10Hz. The effects of the reduced frequency (k), amplitude of forced oscillation (h) and the maximum non-dimensional flapping velocity (kh) on the thrust genera-tion were analyzed. The pressure coefficient CP, lift L, lift coefficient CL, drag coefficient CD and pitching moment M about the support point were computed. The results obtained were compared and agree with the literature ones.