Numerical Analysis of Wing-Tip Flows and Aerodynamic Sound Generated From the Flows

We study the flow and the aerodynamic sound generated from the wing-tip using numerical analysis. The objective of this study is to clarify the contribution to level of sound generated from the wing-tip. We predicted the aerodynamic sound by the separation method based on Lighthill analogy. The model is a rectangular wing having NACA0012 profiles. The shape of wing-tip is blunt, which has sharp edges. The Reynolds number based on the chord length and uniform velocity is 2×10⁵. The angle of attack is 9 degree which is the lifting condition. The flow around the airfoil is predicted by Large-eddy simulation of turbulent incompressible flow. Current results indicated that the simulated surface pressure distribution and pressure power spectrum agreed quantitatively with measured data. In this result, we calculated the Lighthill tensor from velocity and density of air. In addition we discussed the wing-tip vortex structure and its origin. The far field sound predicted by Lighthill tensor shows a similar tendency to the measured data. To investigate the contribution of the overall level around the airfoil with wing-tip, the far field sound was predicted by Lighthill tensor only around wing-tip. The aerodynamic sound level generated from wing-tip is small compared to the overall level of the sound all around airfoil, however it remains possible that contribute to particular frequency band.