| 摘要 |
Low frequency noise and turbulence are reduced in a damper structure by providing a perforate screen extension (31) onto the damper blade (22) so as to extend across the flow path when the damper (20) is open. Additionally, a perforate screen (40) is located immediately downstream of the damper (20) and spaced from the wall so as to define a chamber therewith as well as defining a boundary of the flow path. |
