Modified kappa-epsilon Turbulence Model for Calculating Hot Jet Mean Flows and Noise

Abstract

The κ-e model has no provision to include the effect of the presence of a large-density gradient when used to compute the mean flow and noise of very hot jets. As a result, the model is found to give good predictions only when the jet is cold or moderately hot. Stability consideration indicates that a large density difference across a shear layer would generate strong spatial Kelvin-Helmholtz instabilities. Such instabilities would, invariably, lead to intense mixing in the jet shear layer. This, in turn, gives rise to an increase in turbulence intensity and jet spreading rate. A modification to the κ-e model is proposed to mimic these effects