Context:This postdoctoral position is part of the European project TAKE-OFF (Clean Aviation programme), which is preparing the full-scale flight demonstration of Safran Aircraft Engines’ RISE Open Fan engine on the Airbus A380 flying testbed, with the aim of reducing fuel consumption by 30 % and entering service around 2035.
Without a nacelle, the engine noise sources radiate directly into free field.
LMFA (École Centrale de Lyon), in collaboration with LVA (INSA Lyon), is in charge of analysing the near-field pressure data acquired in flight by microphones installed on the fuselage, in order to reconstruct the engine noise sources.
Objective:To extend the modal analysis methods developed at LMFA for ducted engines [1] to unducted fans.
For the first time, modal analysis will be applied to microphones located in an unconfined medium and to modes radiating under free-field conditions, and design criteria specific to this configuration will be established (spatial sampling, resolution, array-to-rotor distance relative to the array size).
Description:Task 1 – Model and inverse problem.
Build a set of eigenfunctions describing the radiation of an unducted rotor-stator stage (spinning modes weighted by Bessel functions [2], spherical harmonics, etc.
) and embed it in a Bayesian inverse approach [1] to estimate the modal amplitudes of tonal and broadband components.
Flow and fuselage effects may be accounted for through CAA computations.
Task 2 – Validation on the MAMBO database.
The developments will be tested on an unducted propeller + stator configuration recently studied at LMFA (MAMBO project), instrumented with three arrays: a half-cylindrical array, a planar array on the side (representative of fuselage instrumentation) and a motorised arc array measuring directivity, which will serve as an independent reference.
This study will assess the robustness of the method and define array design criteria.
Task 3 – Application to flight tests.
The methodology will be applied.