Acoustics of a Supersonic Mach 1.4 Axisymmetric Spike Inlet

An engine inlet for a supersonic commercial aircraft is analyzed for noise radiation in low-speed configurations for which auxiliary inlet doors are open. Duct modes generated by the fan are estimated by post-processing unsteady Reynold averaged Navier-Stokes (URANS) simulations of the fan and are used as boundary conditions to the inlet domain. Far-field inlet radiated tone levels are computed using commercial acoustics finite element software. The results indicated that the inlet tone levels at cutback and sideline conditions are higher by more than 20 dB than the approach levels.