| 摘要 |
An aircraft turbine engine with a takeoff fan speed and a landing fan speed, the aircraft engine includes a fan duct with a HQ (Herschel-Quincke) acoustic control noise reduction tube. The acoustic control noise reduction tube contains a movable frequency tuner obstruction. The movable frequency tuner obstruction is movable within the acoustic control noise reduction tube, with the movable frequency tuner obstruction movable along a fixed tube path length between a first takeoff frequency obstruction tube path location, and a second landing frequency obstruction tube path location, with the frequency tuner obstruction positioned at the first takeoff frequency location with the takeoff speed, and the frequency tuner obstruction positioned at the second landing frequency location with the landing speed to reduce noise. |
