LARGE EDDY SIMULATIONS OF A GAS TURBINE COMBUSTOR WITH A PARAMETERIZED LINEAR-EDDY MODEL

摘要

Large-eddy simulation of a gas turbine combustor with a subgrid model based on a parameterization of the linear-eddy model (LEM) is presented. The combustor chosen for this study involved the General Electric LM6000 lean pre-mixed, dry, low-NOx combustor. The subgrid model was formulated by populating a database of turbulent flame speed statistics from a LEM - counter flow (CF) solver (Calhoon) that was parameterized in terms of subgrid Reynolds and Karlovitz numbers. This combustor was also modeled using the thin-flame formulation of Pocheau , which was correlated to match experimental flame speed data for methane - air and ethylene -air premixed flames. The LEM-CF subgrid model formulation shows overall good agreement with the experimental data, and a substantial improvement compared to the correlated Pocheau model. The Pocheau formulation, though tuned to match experimental data at different conditions, predicts a much larger turbulent flame speed than the LEM-CF formulation. The basic LEM was calibrated by Smith and Menon using experimental data for premixed flame speeds at different conditions than for the LM6000 case. However, using these same coefficients, the LEM-CF formulation produced good agreement for the LM6000 case. This demonstrates the superiority of the LEM-CF's first principles, physics based prediction of the flame properties, and how its formulation may be applied with a much greater degree of confidence, to conditions different from what it has originally been developed for and tested with.