Internship in Aeroacoustics at Fluid Mechanics and Acoustics Lab (LMFA) of Ecole Centrale de Lyon in collaboration with Airbus & Technofan Context Fluid Mechanics and Acoustics Lab (LMFA) of Ecole Centrale de Lyon (ECL) owns a turbomachinery acoustic test bench made up of a fan of the Environment Control System of Airbus aircraft (Technofan LP3 - Diameter 170mm – Approx 700 l/s) equipped with an instrumentation of acoustic modal detection (both in-duct and in the near field) mounted on a rotating ring, and installed in an anechoic chamber. The installation and tuning of this bench was realised in 2009-2010 with first measurements of inlet aerodynamic distortion in the inlet and of acoustic signatures, and the comparison with analytical prediction models embedded in software OPTIBRUI.

Internship objectives First objective of the internship will be mainly experimental in completing the measurements made in 2010 by an aerodynamic characterisation of rotor wakes upstream of the stator thanks to a cross hotwire probe. Indeed, the impingement of the rotor wakes on the stator is considered on this fan to be the main acoustic source of both tone and broadband noise, and only numerical prediction of the wakes (CFD) are currently available. Measurements will be compared to CFD results and to other measurements performed on a similar fan in another laboratory. Besides, they will be used as inputs of OPTIBRUI software to assess the acoustic prediction models. Second objective will be more theoretical, consisting in the elaboration and implementation in OPTIBRUI of a formulation based on slowly varying modes, both for the acoustic source terms and for the in-duct propagation. Indeed, current models of OPTIBRUI assume an annular duct while duct geometry shows a significant flow cross-sectional passage area variation. The impact of this modelling improvement will then be assessed by comparison to the above-mentioned tests as well as other test cases. Pratical details The internship will be performed in Lyon in LMFA/ECL and will be supervised by Michel Roger, Professeur at ECL. It will done in collaboration with Airbus and Technofan with regular teleconferences or meetings to discuss workplan, results or difficulties. Internship duration is 6 months and it can start in March or April. The end of the internship may be performed in Toulouse by Technofan or Airbus if the student is interested. Contacts Michel Roger – LMFA Thomas Nodé-Langlois – Airbus Patrice Caule – Technofan

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