PIV Investigation of the Flow Past Solid and Slitted Sawtooth Serrated Trailing Edges

Abstract

Turbulent boundary layer trailing edge noise (TBL-TE) is an important source of aeroacoustic noise in many aerodynamic applications. Along with conventional solid sawtooth serrated geometries, new alternative slitted sawtooth design solutions seem to further improve the reduction of TBL-TE noise. In this study, particle image velocimetry (PIV) is used to investigate the flow past solid and slitted sawtooth serrations, installed at the trailing edge of a NACA 0018 airfoil at several angles of attack. Acoustic measurements obtained from a microphone array, in combination with a conventional beamforming algorithm, are employed to investigate the noise reduction obtained from the new serration designs. At zero angle of attack, the PIV measurements show similar mean flow and turbulence statistics between serrated and slitted serrations, despite notable differences in noise reduction. At nonzero incidence, the slitted serrations show less perturbations in the mean and turbulence flow fields with respect to the solid serrations. Despite this, the noise reduction trend seen between the two serration geometries remains similar.