Direct Numerical Simulation of the Flowfield Around NACA0012 Airfoil in Transonic and Low-Reynolds-Number Regimes for Mars Exploration

抄録

Currently, the exploration of Mars using airplanes is being widely studied. In this study, transonic and low-Reynoldsnumber airfoil was investigated using direct numerical simulation to understand its flowfield and aerodynamic characteristics, including unsteady phenomena, in relation to Mars exploration. As a result, we extracted the key features governing the aerodynamic characteristics. Several additional features such as negative lift were identified. For unsteady phenomena, short- and long-period oscillations were the focus of this study. Short-period oscillations were caused by Kármán vortex shedding, which interacted with shock waves and caused weak and short-period shock oscillations. Pressure waves emanating from vortex shedding were observed to propagate both in front of and behind the shock wave. This may have been related to the mechanism of transonic buffet. Long-period oscillations, the so-called low-Reynolds-number buffet, were observed. It exhibited a strong Reynolds-number dependency and attenuated as the angle of attack (AoA) increased. Moreover, it showed differences from transonic buffet at high Reynolds number, such as the onset of oscillation and the role of shock waves in the buffet mechanism. Further investigation of the mechanism of low-Reynolds-number buffets is needed to predict and control for Mars airplanes.