Modelling jet noise installation effects associated with close-coupled, wing-mounted, ultra high bypass ratio engines

Abstract

The research has studied the jet noise installation effects associated with close-coupled, wing-mounted, ultra high bypass ratio engines, which main source is produced by the scattering of the hydrodynamic field passing the wing trailing edge. The objectives of the thesis were to understand the noise generation associated with this mechanism and to produce an analytical methodology able to predict the Sound Pressure Level that is radiated to the far-field.

The hydrodynamic pressure field of a jet is studied from the theoretical and experimental point of view. Whether Lighthill’s acoustic analogy is extended into the near-field by removing the far-field assumptions, three different terms can be found. These terms (near-field term, mid-field term and far-field term) were named regarding the geometric region in which each of them is dominant. When compared against experimental data, the three terms are found and the scaling laws, obtained from the theory, are proof.

Wiener-Hopf technique is then used to obtain an expression for the scattered pressure field and the result is compared with the classic solution from Amiet. The knowledge learnt is used to create a prediction methodology for a static single-stream jet interacting with a parallel flat plate.

More information

Identifiers

Catalogue record

Export record