Acoustic Analysis of STEX Inlet on Fan Noise Radiation

A computational acoustic analysis was completed on a Streamline-Traced External-Compression (STEX) supersonic inlet. The STEX inlet was designed for supersonic cruse at Mach 1.6. Around airports the flight speed will be subsonic and the noise radiated on take-off and approach represents some of the most critical areas of noise acceptance of flight near population centers. The STEX geometry is a non-axisymmetric inlet requiring a 3D analysis of the radiated fan noise. Simulations were conducted for no flow conditions as well as with high-subsonic internal flow and external flow representative of approach velocity. The no flow analysis determined the dominant internal modes and directivity patterns of radiated sound from the inlet. The cases with flow showed significant changes to the mode shapes and directivity patterns. The angle of peak radiated noise was found to be a strong function of frequency.