Numerical optimization of liners for the aero-engine intake of a supersonic aircraft

摘要

During cruise the sonic boom is the main acoustical source of a supersonic aircraft while at takeoff the jet and the fan noises dominate. These different noise sources have been assessed in the European HISAC project dedicated to a supersonic small size transport aircraft. This paper concerns a numerical optimization of liners to reduce the fan noise radiated by the intake. The sound propagation in the intake is predicted using a Boundary Element Method. To save CPU time, the 3D intake is replaced by an axisymmetric geometry, where each run provides the solution at a given azimuthal mode. The optimization includes 3 liner lengths, a matrix impedance of 36 designs and 2 fan noise components: a single engine order associated to each frequency, representative of the buzz saw noise generated by the transonic fan regime and a multi-modal model to describe the broad-band noise.