B. Rembold, L. Kleiser

Recently promising progress has been made in the prediction of noise generation in turbulent free shear flows using DNS and LES. For example, Freund (2001) showed very good agreement of sound-radiation prediction with experiments using DNS and Lighthills acoustic analogy for a Mach 0.9 turbulent round jet. A similar study using LES and Kirchhoffs method was performed by Zhao et al. (2001). It is found in experiments that non-axisymetric jets can radiate less noise than their axisymmetric counterparts. Non-axisymmetric jets have found increased attention (Grinstein, 2001) due to their superior mixing properties, and it is well known that with the different large-scale flow structure of rectangular jets a larger entrainment can be achieved than for round jets. However, only little is known about nozzle shape influence on the detailed transitional flow structures in such geometries that actually cause the sound radiation. To study effects of nonaxisymmetry on transition in a spatially developing rectangular jet with an aspect ratio of five we performed DNS (Rembold et al., 2002a) and LES (Rembold et al., 2001) using the approximate deconvolution model (Stolz et al., 2001a,b). It was confirmed that LES closely agrees with the DNS in particular in the transition region. Large-scale flow structures during rectangular jet break-up were found to be quite different from those for planar or round jets. In the present study we assess the sound source location in the context of Lighthills analogy in the near field of a jet developing from a rectangular nozzle using LES. Since for the jet development the inflow data are crucial, we compare two different cases: Case A, laminar inflow profile with a superimposed dominant linear instability; Case B, fully turbulent inflow data generated in a separate duct flow computation. Sound sources are identified from the LES data base and compared qualitatively.

International Workshop on "LES for Acoustics"; Göttingen; 2002

Conference Paper

englisch

A4, 4 Seiten

DGLR-Bericht, 2002, 2002-03, LES for Acoustics - Proceedings; S.1-4; 2002; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn

NA

in getr. Zählung;

aeroacoustics, large eddy simulation

Bibliothek

2002