초록 ▼

An arrangement for attenuating noise in an air handling unit having a forwardly curved centrifugal fan and dampers downstream of the fan for varying the volume rate of air flow. The dampers are located downstream of the fan a distance L which is about 30 inches so that the critical acoustical freque

An arrangement for attenuating noise in an air handling unit having a forwardly curved centrifugal fan and dampers downstream of the fan for varying the volume rate of air flow. The dampers are located downstream of the fan a distance L which is about 30 inches so that the critical acoustical frequency f=C/4L is relatively high (125 Hz). The discharge section of the air handling unit between the fan and the dampers is lined on the sides with acoustical panels that are effective in absorbing sound at the critical frequency.

대표청구항 ▼

In a variable volume air handling unit having a housing, a fan in the housing presenting a plurality of forwardly curved blades turning about a fan axis to draw air into an inlet side of the fan and discharge the air from a discharge side of the fan, and a duct connected with the discharge side of t

In a variable volume air handling unit having a housing, a fan in the housing presenting a plurality of forwardly curved blades turning about a fan axis to draw air into an inlet side of the fan and discharge the air from a discharge side of the fan, and a duct connected with the discharge side of the fan, the improvement comprising: a damper mounted for opening and closing movement in said duct at a location downstream from the fan axis a distance having the dimension L; and acoustical material in said duct between the fan and damper, said acoustical material having effective sound absorbing ability at a sound wave frequency f=C/4L where C represents the speed of sound.