초록 ▼

An axial fan having a central fan structure from which a plurality of blades extend radially and a center body extending axially from said central fan structure. The center body occupies a volume in which turbulence would otherwise occur. At least one side branch resonator is disposed within the cen

An axial fan having a central fan structure from which a plurality of blades extend radially and a center body extending axially from said central fan structure. The center body occupies a volume in which turbulence would otherwise occur. At least one side branch resonator is disposed within the center body to attenuate resonance produced by said fan in a particular frequency band.

대표청구항 ▼

In combination with a duct and an axial fan having a central fan structure from which a plurality of blades extend disposed within said duct, a noise abatement apparatus comprising: first center body means extending axially from said central fan structure and in alignment therewith in a downstream d

In combination with a duct and an axial fan having a central fan structure from which a plurality of blades extend disposed within said duct, a noise abatement apparatus comprising: first center body means extending axially from said central fan structure and in alignment therewith in a downstream direction for occupying a first volume in which turbulence would otherwise occur and for creating fully developed turbulent flow, said first center body means being in the shape of a figure of revolution having a transition zone tapered radially outwardly from said central fan structure to a center zone having a diameter substantially greater than that of said central fan structure and a terminal zone tapered radially inwardly, said center zone being dimensioned relative to said duct such that an annular space between said center zone and said duct is reduced compared to an annular space between said central fan structure and said duct, whereby said fully developed turbulent flow is initiated; first side branch resonator means positioned within said first center body means for attenuating resonance of at least one frequency band produced by said fan; second center body means extending axially from said central fan structure in an upstream direction for occupying a volume in which turbulence would otherwise occur; and second side branch resonator means positioned within said second center body means for receiving energy traveling upstream through said duct and for attenuating resonance of at least one frequency band produced by said fan.