Wall-modeled large-eddy simulation of a trailing-edge serration-finlet configuration

Abstract

This paper proposes a novel trailing-edge treatment to reduce airfoil self-noise: a serration-finlet configuration. According to the current literature, while serrations are good at reducing low-frequency noise, finlets are able to significantly reduce noise at high frequencies. Therefore, it is possible that their combination can reduce noise at all frequencies. Wall-modeled large-eddy simulations are performed to compare a serration-finlet configuration to a clean airfoil, an airfoil with serrations only, and an airfoil with finlets only. It is shown that the serration-finlet configuration reduces the far-field overall sound pressure level by 20.2 dB and has an improved aerodynamic performance. The detailed flow physics of noise reduction with the serration-finlet configuration is also investigated. It is found that the serration-finlet configuration remarkably reduces far-field noise by improving the hydrodynamic field at source locations. In particular, near-wall velocity and turbulence kinetic energy are reduced. Large coherent eddies are also broken into smaller turbulent structures. The interactions between serrations and finlets are proven to be beneficial from both aerodynamic and aeroacoustic perspectives. Overall, the current research provides a low-noise solution for wind turbines and the future’s ultra-quiet aircraft.