Aircraft today are 20-30 dB quieter than the first passenger jets, emitting less than 1% of the noise. Further reductions in noise emission are a real challenge. The jet noise component is relatively well understood for simple geometries but it is still elusive to accurate and efficient models able to predict it for real turbofan engine nozzle configurations. Enhanced modelling of the complex three-dimensional flow from dual-flux jets of turbofan engines, in which shock waves interact with turbulent structures to generate shock-associated jet noise, is therefore required. This work explores whether lower-order hybrid Detached Eddy Simulation (DES) schemes can be used for aeroacoustic investigations of supersonic under-expanded jets. The objective of this thesis is to produce and analyse aeroacoustic results from under-expanded supersonic single and dual jets with an affordable DES numerical scheme. The main goal is to use a relatively computationally cheap numerical solver able to produce engineering accurate acoustic results for under-expanded jets. Compared to high-order full Large Eddy Simulation (LES) predictions, the second-order time accurate and up to third-order space accurate DES approach here proposed would give a strong advantage in terms of time and computational cost using a fraction of the resources of a full LES. The outcome of the work proves that the adopted approach is suitable for the analysis of BroadBand Shock Associated Noise (BBSAN) in under-expanded supersonic single jets. With respect to dual-flux coaxial jets, further tests are necessary to assess the behaviour of the DES approach in the region of interaction of strong waves with the RANS boundary layer close to the walls in order for the DES approach to be safely and confidently used as a design tool for the engine-airframe integration of wide-body civil aircraft.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:745884 |
| Date | January 2018 |
| Creators | Mancini, Alessandro |
| Contributors | Rona, Aldo ; McMullan, Andrew |
| Publisher | University of Leicester |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/2381/42505 |
Page generated in 0.0169 seconds