Abstract: Provided is a flow modification component for use with a muffler, which can be a Helmholtz resonator muffler, a side branch muffler, or a Y-pipe. The flow modification component includes a porous plate adapted for incorporation into a passage to a sound muffling portion connected to a through passage pipe of the muffler or Y-pipe. One or more openings are formed on the porous plate to allow low frequency acoustic waves to pass through into the passage to the sound muffling portion while reducing large-scale turbulent eddies that produce undesirable resonant tones within the aperture tube to small-scale turbulent eddies. The openings having sufficient porosity such that the resulting sound frequency is determined by size, shape, number, and spacing of the openings. The flow modification component can also include a dissipative material component in an internal port passage of the muffler to further reduce resonant tones.

Abstract: Provided is a flow modification component for use with a muffler, which can be a Helmholtz resonator muffler, a side branch muffler, or a Y-pipe. The flow modification component includes a porous plate adapted for incorporation into a passage to a sound muffling portion connected to a through passage pipe of the muffler or Y-pipe. One or more openings are formed on the porous plate to allow low frequency acoustic waves to pass through into the passage to the sound muffling portion while reducing large-scale turbulent eddies that produce undesirable resonant tones within the aperture tube to small-scale turbulent eddies. The openings having sufficient porosity such that the resulting sound frequency is determined by size, shape, number, and spacing of the openings. The flow modification component can also include a dissipative material component in an internal port passage of the muffler to further reduce resonant tones.