Internal mixing of a portion of fan exhaust flow and full core exhaust flow in aircraft turbofan engines

A method of controlling plume exhaust heat and/or noise radiation from an aircraft turbofan engine assembly having a short nacelle, the method comprising:

• routing a first portion of fan exhaust through a mixer duct between an inner surface of a mixer duct shell and a core engine of the assembly toward a nozzle through which engine exhaust passes;
• and
• routing a second portion of fan exhaust over an outer surface of the mixer duct shell.

An aircraft comprising:

• at least one turbofan engine assembly having a core engine, a short nacelle around a forward portion of the core engine, and a fan duct through the nacelle;
• and
• a mixer duct shell mounted around an aft portion of the core engine and having a forward portion extending forwardly into an exit nozzle of the nacelle to provide a mixer duct between the mixer duct shell and the core engine aft portion.