S0540103 渦法を用いた非定常運動による渦構造の非定常変化の数値シミュレーション

Abstract

In this study, unsteady aerodynamical effects of 2-D airfoil (NACA0012) at the attack of angle 7deg under acceleration or deceleration condition was numerically investigated using a grid-free vortex method. The aerodynamical forces and vortical flow field were compared with each accelerated or decelerated condition at Re=4.0×10^5. In this analysis, firstly, airfoil was moved at a constant speed, and then, each acceleration or deceleration condition was given to the airfoil from the non-dimensionless time T=7.5 at which the fluctuation of fluid forces became stable. The results showed that the aerodynamical forces changed compared with the steady state. Under the large acceleration condition, the lift and drag forces increased with the increase of velocity. Under the large deceleration condition, the lift and drag forces decreased with the decrease of velocity. In addition, Vortex structures generated at the steady motion moved at backward and forward by the acceleration and deceleration motion respectively. Furthermore, it was confirmed that the movement of the vortex structure changed the aerodynamical force.