Assessment of Hybrid RANS/LES Methods For Gas-Turbine Combustor-Relevant Turbulent Flows

摘要

In order to investigate the use of hybrid turbulence models utilizing both Reynolds-averaged Navier-Stokes (RANS) and large eddy simulation (LES) strategies, also known as hybrid RANS/LES, for turbulent gas-turbine combustor-relevant flows, numerical simulations for several representative/benchmark cold-flow cases were performed using a standalone RANS model, a detached eddy simulation (DES) model, a standalone LES model, and a so-called dynamic LES (DLES) model. Predictions of each model were compared to available experimental data. Through this process, the predictive performance of DES, a common hybrid RANS/LES method, was shown to be subject to several established deficiencies, such as modelled stress depletion (MSD) for some of the benchmark cases studied. These issues proved to be a disadvantage when compared to the other modelling strategies for cases with simple geometry and flow structures. However, it was shown that a fine pre-LES zone mesh could be used to manipulate MSD regions and improve DES performance. Additionally, the predictive performance of DES was significantly improved in comparison to the other treatment techniques for turbulence for cases with greater complexity in flow geometry and features, such as swirl. The latter are more representative of the turbulent flows of interest here.