Noise reduction of serrated trailing edges with implicit large eddy simulation using PyFR

Abstract

Inspired by the silent flight ability of owls, the design of sawtooth trailing edges has been considered a promising way to control the interference noise when an incoming turbulent boundary layer passes through a sharp trailing edge. To this end, the flow and noise generation for different trailing-edge serrations are explored by the wall-resolved implicit large-eddy simulation (ILES) and acoustic analogy using PyFR. It was found that the size and shape of serrations could significantly affect noise reduction in the far field. The velocity profile and the distribution of Reynolds stress components show that the serrations mainly change the flow near the trailing edge and have little effect on the upstream flow. Furthermore, correlation analysis and dynamic mode decomposition (DMD) are used to confirm that destructive interference is the primary mechanism responsible for noise reduction. Since flow structures are reorganized near the TE serrations, we investigated the flow noise sources quantitatively in the near field. We found that the effect of vortex structures near the side edges of the serrations should be considered in the optimal design.