Computational-Fluid-Dynamics-Based Clean-Wing Aerodynamic Noise Model for Design

A new noise metric is developed for clean-wing aerodynamic noise modeling that may be used in aircraft or wind turbine design studies involving aerodynamic noise. The method uses Reynolds-averaged Navier-Stokes calculations with a two-equation turbulence model to include the effects of the lift coefficient, flow three-dimensionality, and wing design parameters on the trailing-edge noise. These effects are not considered in the existing, relatively less expensive, semi-empirical noise prediction methods. The proposed noise metric is not the exact value of the noise intensity, but it is a relative noise measure suitable for design studies. The new noise metric is less expensive to compute compared to the full-noise calculations done with computational aeroacoustics methods, and it can be easily implemented using the solutions of Reynolds-averaged Navier-Stokes simulations that may have already been performed as part of the aerodynamic design and analysis. Parametric studies were performed to investigate the effect of the wing geometry and the lift coefficient on the noise metric. Two-dimensional studies were done using two subsonic (NACA 0012 and 0009) and two supercritical [SC(2)-0710 and -0714] airfoils. The energy-efficient transport wing (a generic conventional transport wing) was used for the three-dimensional study. Both two-and three-dimensional studies show that the trailing-edge noise increases significantly at high lift coefficients. The three-dimensional effects observed in the parametric wing study indicate the importance of calculating the noise metric with a characteristic velocity and length scale that vary along the span.