PhD - Inverse modal identification of free-field radiated noise from unducted rotor-stator stages: from laboratory arrays to Open Fan flight tests

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 s