A multi-objective optimization of a wave-packet model using near–field subsonic jet data

Aeroacoustic analyses of new generation and highly innovative aircraft configurations such as Hybrid and Blended Wing Body cannot disregard the development of low-order models for the jet noise source, essential to assess the propulsion-airframe interactions since the conceptual/preliminary design stage. The use of wave-packets to model jet noise is based on the widely accepted hypothesis that the large-scale turbulent structures, responsible for noise peaks emitted by subsonic and supersonic jets, can be modelled as instability waves that grow and then decay with axial distance. In this study, a M=0.9 high-subsonic jet is represented as a cylindrical surface radiating the pressure disturbances of a wave-packet source, whose parameters are optimized using near-field information from LES simulations. The importance of calibrating the model with near-field pressure data stems from the fact that innovative aircraft configurations have engines nacelles typically positioned at a few diameters from the wing or fuselage. The main scope of this analysis is to provide a noise source model that can be coupled with Boundary Elements Method (BEM) codes for aeroacoustic scattering evaluations. A quite good agreement is achieved at multiple near-field radial distances between the simulation data and model prediction for the dominating 0tℎ azimuthal mode at the selected Strouhal numbers up to 1.