THE TUBULAR NOISE MUFFLER USABLE IN DUCT FAN DEVICES Russian patent published in 2007 - IPC F04D29/66 

FIELD: ventilation engineering.

SUBSTANCE: device has casing rigidly connected to end face inlet and outlet branch pipes, sound absorber unit placed between casing and perforated member, and acoustically transparent material located between the perforated member and sound absorber. The ratio of external muffler case section side C to its length L belongs to optimum size interval of C/L= 0.44...1.11; the ratio of internal muffler case section side A to its length L belongs to optimum size interval of A/L= 0.25...0.9; the ratio between the external and internal muffler case section side lengths difference and its length belongs to optimum size interval of (C-A)/L = 0.192...0.21; the attitude of branch pipes lengths a to muffler length L belongs to optimum size interval of a/L = 0.05 - 0.07. The sound absorber is manufactured from cotton wool mineral on basalt base or glass wool material with fiber glass felt material coating, or foam polymer. Sound-absorber member is coated with acoustically transparent material allover its surface.

EFFECT: enhanced effectiveness in muffling noise.

2 dwg