Bypass device for noise reduction of a blower stage of a gas turbine jet

摘要

A nacelle for use with a turbofan engine for reducing both rotor and stator source noise emitting from the engine. The nacelle contains a ducted system which when in operation bypasses a portion of the flow in the fan duct around the fan stators causing unloading of the rotor, diffusion of the flow between the rotor and the stators, a reduction in the viscous flow at the rotor tips, and a substantial elimination of the rotor tip flow. Flow enters the duct system through openings in the interior walls of the nacelle located between the rotor and fan stators but downstream of the rotor at least a certain predetermined minimum distance. Flow through the system is controlled by doors or other means and it is normally operated only during approach and take-off, thus minimizing cruise penalty on engine performance.