The effects of temperature on supersonic jet noise emission
ABSTRACT This paper examines the generation of sound produced by high temperature supersonic jets. In particular, the question of the importance of supersonic instability waves to noise emission is considered relative to the role of Kelvin-Helmholtz (K-H) instability waves. Here, these waves are taken to be synonymous with the Mach emission process. Jet total temperatures from 313 to 1534 K are investigated using an axisymmetric water cooled supersonic nozzle designed for Mach 2. The aerodynamic and acoustic results of this study indicate that the dominant noise contributors are the K-H waves over the entire temperature range. Good agreement between measured and numerically predicted plume properties are obtained and an elliptic nozzle is used to demonstrate reduction of the K-H waves.
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ABSTRACT: The WIND code, a Reynolds-averaged Navier-Stokes solver used for a variety of aerospace flow simulations, was investigated for a Mach 2 nozzle at a series of nozzle stagnation temperatures. Comparisons of WIND calculations are made to experimental measurements of axial velocity, Mach number, and stagnation temperature along the jet centerline. The primary objective was to investigate the capabilities of the two-equation turbulence models available in WIND, version 4.0, for the analysis of heated supersonic nozzle flows. The models examined were the Menter Shear Stress Transport (SST) model and the Chien k-epsilon model, with and without the compressibility correction due to Sarkar. It was observed that all of the turbulence models investigated produced solutions that did not agree well with the experimental measurements. The effects of freestream Mach number and turbulent Prandtl number specifications were also investigated.09/2002;
Article: Effet de la température sur les caractéristiques aérodynamiques de jets chauds turbulents à partir de mesures par Vélocimétrie Laser à Effet Doppler[show abstract] [hide abstract]
ABSTRACT: Les écoulements turbulents chauffés sont d’un grand intérêt dans le domaine aéronautique. Le champ aérodynamique d’un jet libre dont le nombre de Reynolds varie entre 35 000 et 100 000 et la température entre 315 et 460 K a été étudié par Vélocimétrie Laser à effet Doppler. Les résultats montrent entre autres un raccourcissement du cône potentiel et une augmentation des tensions de Reynolds sur l’axe du jet avec la température ainsi qu’une diminution du nombre de Strouhal des instabilités.
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ABSTRACT: The goal of this study is to apply the Muscl scheme to the linear advection equation on general unstructured grids and to examine the eigenvalue stability of the resulting linear semi-discrete equation. Although this semi-discrete scheme is in general stable on cartesian grids, numerical calculations of spectra show that this can sometimes fail for generalizations of the Muscl method to unstructured three-dimensional grids. This motivates our investigation of the influence of the slope reconstruction method and stencil on the eigenvalue stability of the Muscl scheme. A theoretical stability analysis of the first order upwind scheme proves that this method is stable on arbitrary grids. In contrast, a general theoretical result is very difficult to obtain for the Muscl scheme. We are able to identify a local property of the slope reconstruction that is strongly related to the appearance of unstable eigenmodes. This property allows to identify the reconstruction methods that are best suited for stable discretizations. The explicit numerical computation of spectra for a large number of two- and three-dimensional test cases confirms and completes the theoretical results.Numerische Mathematik 04/2012; 113(4):555-600. · 1.32 Impact Factor