Turbofan engine noise suppression using fan flow deflector

A turbofan noise suppression system comprising:

• a substantially annular fan nozzle and a core nozzle of a separate-flow turbofan engine, the fan nozzle having a flow boundary surface and an outlet to discharge a fan stream into atmosphere, the core nozzle discharging a primary stream into the atmosphere, the fan stream and the primary stream being substantially coaxial;
• and
• a plurality of vanes attached to the fan nozzle and extending substantially radially from the flow boundary surface, the vanes include a leading edge, an upper surface and a lower surface that are in contact with the fan stream, the upper surface being opposite to the lower surface, the vanes having a first position (i) where at least one of the upper surface and the lower surface is substantially aligned with the fan stream and (ii) where the trailing edge is at a first location, and a second position where (i) the at least one of the upper surface and the lower surface is angled with respect to the fan stream and (ii) where the trailing edge is at a second location, and (iii) vectoring at least a portion of the fan stream toward a direction where noise suppression is desired such that an overall direction of the fan stream is not aligned with the primary stream, wherein the vanes are immersed into the fan stream in the first position and in the second position such that the upper and the lower surfaces are in contact with the fan stream in the first position and in the second position, the vanes being situated in proximity of the outlet of the fan nozzle and having a span substantially greater than a thickness of a local boundary layer of the fan air.