An alternative permeable topology design space for trailing-edge noise attenuation

This study focuses upon a new permeable topology design concept as an alternative to porous metal foams, for turbulent boundary layer trailing-edge (TBL-TE) noise attenuation. The present has unconventional characteristics with respect the foams: combination of low flow resistivity r and high form drag coefficient C. are realized by Kevlar-covered 3D-printed perforated structure. An experimental featuring NACA 0018 airfoil model TE insert at chord-based Reynolds numbers up [Formula: see text] is carried out. this gives broadband TBL-TE reduction approximately 5 dB, compared solid TE. varies only slightly loading (lower than 1 dB variation), in contrast foams (up 3 variation). When comparing variation attenuation given all materials considered, found decrease increasing because C specifies material's ability withstand pressure difference, which causes cross that might interfere mechanism. Additionally, coefficients well roughness equipped also significantly lower those metal-foam TE, mostly negligible fully airfoil. Based on findings, guidelines proposed: material shall have surface roughness.