Fan with reduced noise generation

Details Fan with reduced noise generation Fan with reduced noise generation

2005-03-29

2005-03-29

Leo, Leonard R. (Department: 3753)

Rotary kinetic fluid motors or pumps

With sound or vibratory wave absorbing or preventing means...

C416S228000, C416S235000, C416S23600R

Reexamination Certificate

active

06872048

ABSTRACT:
Axial flow fan propellers are provided with a roughened portion along the trailing edge of the fan blades on the pressure side of the blade to minimize tonal acoustic emissions generated by laminar boundary layer vortex shedding. The roughened portion may be provided by trip surfaces formed in the blades, by strips of abrasive material adhered to the blades along the trailing edges, respectively, by parallel or cross-hatched serrations in the blades or by upturned or offset trailing edges of the blades. The height of the roughened portion should be about equal to the boundary layer thickness of air flowing over the blade surfaces during operation of the fan. The fan propellers are particularly advantageous in heat exchanger applications, such as residential air conditioning system condenser units.

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