TUBULAR NOISE SUPPRESSOR TO CHANNEL FANS Russian patent published in 2010 - IPC F01N1/00 

FIELD: machine building.

SUBSTANCE: tubular noise suppressor consists of case of rectangular cross section rigidly connected to end inlet and outlet branches, of sound absorber located between case and perforated element, and of acoustic transparent material installed between perforated element and sound absorber. The sound absorber contains a rigid wall whereto a shaped layer of a triangle profile out of sound absorbing material is attached with air gap. Opposite to it the shaped layer of a triangle profile out of sound absorbing material is attached to the perforated element of the case with air gap. Between the shaped layers there is ensured air interval, and a recess of one layer is opposite to a projection of another. Also surfaces of profiles are made congruent and are offset at value equal to half of length of triangle base. Acoustic transparent material is arranged between the shaped layer and the perforated element of the case. Density of sound absorbing material of shaped layers is different: density of the layer secured to the rigid wall is higher, than density of the layer attached to the perforated element of the case. As sound absorbing material of the shaped layer at the rigid wall there is used rigid porous noise absorbing material, for example aluminium foam or metal ceramic, or metal foam rubber, or sound absorber on base of aluminium containing alloys with their successive filling with titanium hydride or air of density within ranges 0.5…0.9 kg/m³ and with following strength properties: compression strength within limits 5…10 MPa, and bending strength within 10…20 MPa. As sound absorbing material of the shaped layer at the perforated element there is used sound absorber out of mineral wool on basalt base of "Rockwooll" type or mineral wool of "URSA" type, or basalt wool of "П"-75 type; or glass wool with glass felt coating, or of foam polymer, for example polyethylene and/or polypropylene. Notably, the sound absorbing element is coated with acoustic transparent material, for example glass cloth of EZ-100 type or polymer of "Poviden" type along its whole surface.

EFFECT: increased efficiency of noise suppressing.

3 dwg