迎え角変動がある翼端渦挙動と発生する空力騒音に関する研究

抄録

To clarify the aerodynamic noise characteristics of an NACA0012 airfoil with a blunt wingtip by means of Large Eddy Simulation and Computational Aeroacoustics, we calculated the characteristic St numbers, which were 0.1, 0.3, and 0.5 for the angles of attack of 10° and 12° ± 2°. The Reynolds number based on the chord length of the airfoil and uniform flow velocity was 3.0 × 10⁵ for the constant angle of attack and 2.0 × 10⁵ for the oscillating airfoil. The flow field and the acoustic field around the airfoil were calculated using hexahedral meshes. As a result, the tip vortices were found to merge at x/C = 0.75 and form the main noise source. The directional characteristics of acoustic radiation showed a dominant quadrupole at St = 10. Pressure fluctuation on the wingtip at St = 0.1 was the same as that in case of constant angle of attack. At St = 0.5, the vortex structure disappeared because of increased pressure fluctuation, which reached 15% of chord length. Therefore, we concluded that the noise generated due to tip vortex formation is dependent on St.