US Patent 7631483 Method and system for reduction of jet engine noise

In an aspect, a method is provided for attenuating jet engine noise. Air velocity, adjacent to an inlet fan duct outer wall, is increased to a greater rate than typical velocity of an operational engine ambient inlet airflow, adjacent to the inlet fan duct outer wall. Boundary layer and associated turbulence is reduced or eliminated. Refraction and absorption of inlet sound into an acoustic liner is optimized. In an aspect, air velocity is increased by injecting air. In an aspect, air velocity is increased by exerting a suction force. In an aspect, a system is provided to attenuate jet engine noise. In an aspect, a fluid duct is provided opening to an inlet fan duct outer wall and to aft of a fan rotor.