Time domain wave packet method and suppression of instability waves in aeroacoustic computations

A new time domain methodology for Computational Aerocoustics (CAA) is proposed. The Time Domain Wave Packet (TDWP) method employs a broadband temporally compact pulse at the acoustic sources. Radiation and transmission of acoustic waves of all frequencies within the numerical resolution is embedded in the propagation of the wave packet. In addition, it becomes possible to separate the acoustic and instability waves in shear flows in the Time Domain Wave Packet method. The instability waves are suppressed by a source filtering technique, applied after the acoustic wave packet has mostly propagated through the shear layers. Details on the source filtering technique are presented in the paper. The TDWP method has been validated using CAA Benchmark problems and using numerical results of circular and annular ducts with flow. The TDWP method is further applied to the NASA/GE Fan Noise Source Diagnostic Test (SDT) exhaust radiation problem.