Numerical Simulation of Separated Flows around a Wing Section at Steady and Unsteady Motion by a Discrete Vortex Method

概要

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Separated flows around a wing section at fixed attack angle of an oscillating airfoil are simulated numerically by a discrete vortex method combined with a panel method. The potettial flows around wing sections are expressed by vortex sheets and separated shear layers are expressed by discrete vortices. In the calculation a separation point is determined by solving boundary layer equation. The strength of shed vortex is estimated using local velocity near separation point. Also modification for the estimation of pressure coefficients around wing section are proposed. The estimated pressure distributions show good agreements with experimental results. Aerodynamic characteristics of a wing section of NACA4412 are predicted with excellent agreement with experiments. Also separated flows around pitching airfoils are simulated for various conditions. A hysteresis of lift of airfoil at dynamic stall is obtained. Further unsteady flow caused by abrupt change of the attack angle from 10 to 20 degrees is simulated numerically. The transient flow patterns show significant characteristics of unsteady flow. The hysteresis of the lift of piching airfoil is simulated properly.
宇宙航空研究開発機構の論文