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September 17, 2018: "Introduction to Vortex Sound Theory and application to the prediction of vortex pairing noise"

  • September 17, 2018
  • 4:00 p.m.
  • 320 New Classroom Building
  • Dr. Christophe Schram, von Karman Institute for Fluid Dynamics
  • Faculty Host: Dr. William Devenport

Abstract: The aeroacoustic analogy proposed by Lighthill in the fifties provides a theoretical framework that has made possible the successful prediction of the noise emitted by free turbulent flows in numerous instances. Yet, the form taken by the equivalent source term of this analogy (involving the Reynolds stress tensor) is causing some numerical difficulties in some cases, related to the relatively large spatial spreading of the apparent source field, extending to relatively quiet regions of the flow. Vortex Sound Theory (VST) proposes a reformulation of the aeroacoustic analogy in which the source term involves the vorticity, which leads to a much more concentrated distribution of equivalent sources in most flows. In addition, in some cases this formulation permits the recurrent imposition of physical assumptions that do considerably reinforce the numerical robustness of the noise prediction. Those concepts are illustrated through the application of a so-called conservative formulation of Powell/Möhring VST to an academic vortex interaction: the leapfrogging and merging of two vortex rings. It is demonstrated that the conservative VST formulation enables an accurate prediction of the noise emitted by this mechanism, even when an experimental description of the flow field – inherently contaminated by measurement errors – is used as input.

Bio:

1997: Engineering degree in Mechanical and Electrical Engineering, Université Libre de Bruxelles, Belgium.

1998: Research Master in Fluid Dynamics, von Karman Institute for Fluid Dynamics (VKI), Belgium.

2003: PhD degree in aeroacoustics, von Karman Institute for Fluid Dynamics, Belgium, co-tutelle between the Technische Universiteit Eindhoven, Netherlands , and the Université Libre de Bruxelles, Belgium.

2004: Research Associate, University of Cambridge, UK. Research topic: thermo-acoustic instabilities in gas turbines.

2005-2009: Aeroacoustics Project Leader and RTD Project Manager, LMS International (now Siemens Industry Software), Belgium. Leading the numerical aeroacoustics developments and coordinating regional, national and European research projects.

2009- : Assistant Professor, Associate Professor and Professor at VKI. Research interests: theoretical, numerical and experimental aeroacoustics, aircraft and personal air vehicle noise, low-speed rotating machinery noise, low-speed and supersonic jet noise, aero-acoustic and thermo-acoustic resonances in industrial systems, fluid-structural interaction and noise transmission through flexible panels, ducted aeroacoustics and multi-ports, acoustic beamforming techniques.

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