Assessment of k-ε / EASM Turbulence Model Upgrades for Analyzing High Speed Aeropropulsive Flows*

This paper discusses the numerical simulations of selected high-speed aeropropulsive applications including axisymmetric supersonic base flowfields, with and without jets, and three-dimensional supersonic hot jets. Comparisons are made using a compressibility corrected k-ε turbulence model and an Explicit Algebraic Stress Model (EASM). The present EASM, referred to as EASM/J, has been modified to correctly predict the mixing of basic jet and free shear flows. A structured, parallel, finite-volume, Navier Stokes code, CRAFT CFD is used as the flow solver. In the present study, the EASM/J analysis assumes a fixed (equilibrium) value of production-to-dissipation ratio. The effect of the compressibility correction as implemented in CRAFT CFD, in predicting the flow reattachment location and base pressure distribution is investigated. For base region studies, the k-ε and EASM/J models predict comparable results, but base pressure distributions are closer to the experimental data without using the compressibility correction. For the jet with base study, the predictions with and without the correction bound the data. For the three-dimensional cases, there is no substantive difference in mean flow predictions using k-ε and EASM/J.