초록

Oscillating airfoil has been challenged for the dynamic stalls of airfoil and wind turbines at ahigh angle of attack. Especially, the pressure oscillation has a huge effect on noise generation, structuredamage, aerodynamic performance and safety, because the flow has strong unsteadiness at a high angleof attack. In this paper, the unsteady aerodynamics coefficients were analyzed around a two dimensionaloscillating NACA0012 airfoil at high angle of attack. The two dimensional unsteady compressibleNavier-Stokes equation with a LES turbulent model was calculated by OHOC (Optimized High-OrderCompact) scheme for space derivatives and 4th order Runge-Kutta scheme for time derivatives. The flowconditions are Mach number of 0.2 and Reynolds number of  ×  . The periodic angle of attack isgiven as . Several cases of the combinations of the mean and amplitude of angle of attacks have beencalculated. The coefficients of lift and drag, pressure distribution, etc. are analyzed according to thepitching oscillation. Unsteady velocity field, periodic vortex shedding, the unsteady pressure distribution,and the acoustic fields are analyzed. The effects of these unsteady aerodynamic characteristics areanalyzed by FFT at a high angle of attack.

키워드

Unsteady Subsonic Flow, Oscillating Airfoil, Optimized High Order Compact Scheme, High Angle of Attack

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