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Aeroelastic Simulation of Stall Flutter Undergoing High and Low Amplitude Limit Cycle Oscillations
Author(s): Khairil Hafizi Zorkipli, A. Abas, N. Razak
Keywords: Stall flutter, limit cycle oscillation, flow separation, dynamic stall
The aeroelastic behaviour of an airfoil oscillating in large and small pitch amplitudes due to nonlinearity in aerodynamics is examined. The phenomenon of stall flutter resulted in the limit cycle oscillations of NACA 0012 at low to intermediate Reynolds number is investigated numerically through the unsteady two-dimensional aeroelastic simulation. The simulations employed unsteady Reynolds Average Navier Stokes shear stress transport k-ω turbulent model with the low Reynolds number correction. The simulations of the fluid-structure interaction were performed by coupling the structural equation of motion with a fluid solver through the user-defined function utility. Numerical simulations were executed at three different elastic axis positions; the leading-edge, 18% and 36% of the airfoil chord length. The airfoil chord measures 0.156 m. The simulations were executed at the free stream velocity ranging from 5.0 m/s to 13 m/s corresponding to the Reynolds number between 51618 and 134207. Two types of oscillation amplitudes were observed at each elastic axis position. At the leading-edge and 18% case, small amplitude oscillations were observed while at 36%, the system underwent high amplitude oscillations. The analysis revealed the cause for small oscillation amplitude is due to the separation of the laminar boundary layer on the suction side of the airfoil starting at the trailing edge. High amplitude oscillations occurred due to the existence of the dynamic stall phenomenon beginning at the leading-edge. Small amplitude LCOs only occurred within a limited range of airspeed before it disappeared due to increasing airspeed.

Journal of Applied Fluid Mechanics

The Journal of Applied Fluid Mechanics (JAFM) is an international, peer-reviewed journal which covers a wide range of theoretical, numerical and experimental aspects in fluid mechanics. The emphasis is on the applications in different engineering fields rather than on pure mathematical or physical aspects in fluid mechanics. Although many high quality journals pertaining to different aspects of fluid mechanics presently exist, research in the field is rapidly escalating.