Numerical Simulations of Nonreacting Flows for Industrial Gas Turbine Combustor Geometries

Abstract

This study evaluates the application of the computational fluid dynamics (CFD) to calculate the flowfields in industrial combustors. Two-burner test cases, which contain the elemental flow characteristics of an industrial gas turbine combustor, are studied. Comparisons were made between the standard k-epsilon turbulence model and a modified version of the k-epsilon turbulence model. The modification was based on the work of Chen and Kim in which a second time scale was added to the turbulent dissipation equation. Results from the CFD calculations were compared to experimental data. For the two-burner test cases under study, the standard k-epsilon model diffuses the swirl and axial momentum, which results in the inconsistent prediction of the location of the recirculation zone for both burner test cases. However, the modified k-epsilon model shows an improved prediction of the location, shape, and size of the primary centerline recirculation zone for both cases. The large swirl and axial velocity gradients, which are diffused by the standard k-epsilon; model, are preserved by the modified model, and good agreements were obtained between the calculated and measured axial and swirl velocities. The overprediction of turbulent eddy viscosity in regions of high shear, which is characteristic of the standard k-epsilon model, is controlled by the modified turbulence model.