Beamforming-Based Wavepacket Model for Noise Environment Predictions of Tactical Aircraft

Jet noise consists of extended, partially correlated sources such that a single-wavepacket source representation is inadequate. A multiple-wavepacket (MWP) model provides an analytical framework for jet-noise-like radiation to simulate jet noise field levels as well as the corresponding spatial coherence properties within the field. Here, a beamforming method with regularization is applied to noise measured by a linear array near a high-performance military aircraft. Beamforming results are decomposed into a reduced-order MWP model and the predicted radiation is validated in terms of level and coherence properties using benchmark measurements. 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. The MWP model is shown to predict full-scale specific features such as multilobe directivity patterns, and the addition of an uncorrelated distribution (UD) model adequately predicts the sideline radiation that is otherwise difficult to reproduce from wavepacket radiation. The MWP model predicted radiation characteristics are an improvement over single-wavepacket models, which do not incorporate spatiotemporal features of the radiation.