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Theses

Etude mathématique et numérique de la propagation acoustique d'un turboréacteur

Abstract : This thesis deals with the industrial problem of modelisation and numerical simulation of the acoustic radiation from fan duct air entry. The physical hypothesis subsequent to the industrial framework give way to a simplified model of linear acoustic propagation upon a non linear potential flow. Engine modal noise source modelisation requires acoustic boundary conditions through a Dirichlet-Neumann operator. Existence and uniqueness of the global mathematical problem (a convected Sommerfeld condition is added) of the potential and local perturbation from a uniform flow are prooved. A discrete coupling between the volumic acoustic potential (finite volumic elements) and its elliptic normal derivate (boundary finite element) through an integral equation is exhibed. Computing code is validated analytically and comparatively. Original results are described and prove the necessity to consider the nonlinearity of the flow by differences greater than 5 dBs in the far field acoustic diagrams. Optimal positionning of the radiating surface and the plugability of the fast multipole method make this coupling unmissable. Simplified potential-linear model, even if its range of validity is restricted to the fan duct air entry, gets his whole interest as a brick in a global domain decomposition code. By the way, lets mention the achievement of a natural axisymetric finite element and an alternative method to the calculus of the non linear flow by a fixed point method.
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Theses
univLorraine_urlFulltext :
http://docnum.univ-lorraine.fr/prive/SCD_T_2006_0185_DUPREY.pdf
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https://hal.univ-lorraine.fr/tel-01746556
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Submitted on : Thursday, March 29, 2018 - 10:40:13 AM
Last modification on : Tuesday, March 2, 2021 - 5:12:06 PM

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  • HAL Id : tel-01746556, version 1

Citation

Stefan Duprey. Etude mathématique et numérique de la propagation acoustique d'un turboréacteur. Mathématiques générales [math.GM]. Université Henri Poincaré - Nancy 1, 2006. Français. ⟨NNT : 2006NAN10185⟩. ⟨tel-01746556v1⟩

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