Three-dimensional aspects of airfoil turbulence-impingement noise and its reduction by porous cells or wavy leading-edge design
Composition du jury :
Pr. AZARPEYVAND Mahdi, University of Bristol, Rapporteur
Pr. GERVAIS Yves, Université de Poitiers, Rapporteur
Pr. MOREAU Stéphane, Université de Sherbrooke, Examinateur
Dr. AYTON Lorna, University of Cambridge, Examinatrice
Dr. HERR Michaela, German Aerospace Center (DLR), Jury member, Examinatrice
Pr. SCHRAM Christophe, von Karman Institute, Co-directeur de thèse
Pr. ROGER Michel, École Centrale de Lyon, Directeur de thèse
Lien pour la visioconférence
ID de réunion : 996 3375 6969
Code secret : 072625
Résumé
Broadband noise radiated from airfoils has been considered as a generic problem of primary engineering and research interest along the last decades. Noise emission from turbofan engines, drones, ventilation systems and other industrial and domestic applications could be mainly characterized as broadband and airfoil turbulence-impingement noise (TIN) is its dominating contributing mechanism. The present work investigates the three-dimensionality of TIN and its mitigation by wavy leading-edge designs or porous inclusions. Experimental techniques and analytical models for the noise predictions are the main tools used for these investigations. A combination of far-field (single microphone) and near-field (spiral antenna) measurements showed consistent results with previous studies and highlighted the trailing edge noise (TEN) detrimental effect on the airfoil noise reduction performances. Results show that TIN reductions extend linearly for flat plates and exponentially for thick airfoils over a wider low-and-middle frequency range after subtracting TEN. Noise prediction tools for TIN have been validated both for straight and wavy leading edges by making use of the obtained experimental results. A flow analysis around the wavy leading edge performing tomographic and stereoscopic PIV measurements has been performed. Results are in agreement with previous works, and allow validating computational simulations in configurations similar to the present experiments. Considering simple serration designs on leading edge and trailing edge, an optimization strategy is proposed for minimizing the total noise of an airfoil. The acoustic and aerodynamic exploration of porous airfoils indicates porosity as a promising technique for the noise mitigation of thick airfoils, with potentiality similar to that of leading-edge serrations for fans and other industrial applications.
Lien pour la visioconférence
ID de réunion : 996 3375 6969
Code secret : 072625
