15H40 : n° 926 Couplage de méthodes hybrides acoustiques pour la prévision du bruit de jet par Simulation des Grandes Echelles

Guillaume Bodard Christophe Bailly
SNECMA
Une méthode hybride de prévision de bruit de jet à partir d’une Simulation des Grandes Echelles est développée et appliquée à deux jets subsoniques. Elle couple la méthode d’extrapolation des ondes acoustiques de Ffowcs-Williams & Hawkings pour les basses fréquences et le modèle du bruit de la turbulence fine de Tam & Auriault au-delà. Les champs aérodynamiques sont en accord avec les expériences, malgré une surestimation du mélange entraînant une légère surévaluation des niveaux acoustiques.

16H00 : n° 1065 LES of different flow states around a cylinder plate configuration and corresponding aeroacoustic effects

Michael Kornhaas Michael Winkler Dörte Sternel Klaus Becker Michael Schäfer
Chair of Numerical Methods in Mechanical Engineering
A LES of the flow around a cylinder plate configuration as well as experimental data of the corresponding sound pressure spectrum are presented. Depending on the distance between plate and cylinder an intensive tonal noise can be observed. Three different states can be distinguished. For small distances the tonal noise is not present. For a certain distance the tonal noise occurs sporadically and for bigger distances the tonal noise is permanently present.

16H20 : n° 1023 Applications of a high-order algorithm for LES and CAA in complex geometries

Frédéric Daude Julien Berland Philippe Lafon Fabien Crouzet Christophe Bailly
LaMSID - UMR EDF/CNRS 2832
In confined flows, non-linear interactions between acoustics and aerodynamics produce high pressure levels. To tackle these couplings, a numerical tool is developed: Code_Safari. It is based on optimized high-order finite-difference schemes in conjunction with optimized filters on a multi-domain approach. A shock-capturing filter is also applied. Code_Safari is validated on classical test problems and used for realistic applications (ducted cavity, sudden enlargement, rod-airfoil interaction).

16H40 : n° 1224 Direct acoustic computations of cold and heated jets

Marie Cabana Véronique Fortuné Yves Gervais
Laboratoire d'Etudes Aérodynamiques
Round jets having a Mach number of 0.9 and a Reynolds number of 1700 are computed by direct numerical simulations using a characteristic-type formulation and high-order compact finite differences. Two simulations are carried out where the ratio of inflow to ambient temperature is equal to 1 (isothermal jet) and to 2 (anisothermal one) respectively. The influence of the jet temperature on the main features of the flow and its associated sound field is investigated.

17H00 : n° 555 Noise Sources in Heated Coaxial Jets

Seong Ryong Koh Wolfgang Schröder Matthias Meinke
Institute of Aerodynamics RWTH Aachen University
Recently, based on the most novel investigations a jet noise mechanism is proposed to have similarity spectra for the two components of turbulent mixing. The principal result of this theory on hot jets motivates the present numerical analysis about acoustic sources. Using the terms of acoustic perturbation equations the noise source inside hot coaxial jets is analyzed. The findings will evidence the acoustic radiation to be intensified by the pronounced temperature gradient.