Wavepacket Modeling and Full-scale Military Jet Noise Beamforming Analyses

Because jet noise consists of extended, partially correlated sources, a multi-wavepacket model is appropriate to simulate jet noise field levels as well as the appropriate spatial coherence properties within the field. Here, the Hybrid method is used to reconstruct the levels and coherence properties of the source region for multi-wavepacket numerical models. The beamforming source results are then propagated to the acoustic field, where they show good agreement with benchmark levels and coherence lengths. The Hybrid method is further applied to a planar measurement of noise near a high-performance military aircraft, and the beamforming results are propagated to a ground-based microphone array. Sound levels and coherence lengths generated by the beamforming results show good agreement with benchmark measurements over a range of frequencies that contribute significantly to the overall radiation. Results indicate that the multi-wavepacket representation is an improvement over single-wavepacket models, which do not incorporate spatiotemporal features of the radiation.