Prediction of Jet Noise Shielding

This study is motivated by the development of aircraft that use jet noise shielding by the airframe. Current methods to predict shielding from aircraft surfaces rely on formulae developed for diffraction of sound from omnidirectional point sources. However, the jet noise source is distributed and directional, thus requiring a different approach. In this study, the jet noise source is modeled as the incoherent superposition of a wavepacket and a monopole. Source parameterization and application of minimization methods are used to match the directivity of the far-field sound at a given frequency. The resulting incident field is then used to compute the diffraction problem using the Boundary Element Method. Reasonable agreement is found with experimental data, suggesting the applicability of the wavepacket ansatz in modeling the jet noise source.