Budgets of turbulent kinetic energy in an abruptly expanding circular duct

The flow characteristics downstream of an axisymmetric sudden expansion is of basic importance to designers of gas turbine and solid-fuel ramjets. There is no doubt that the understanding of their complex flowfield will help in improving their design. Detailed measurements were made in an axisymmetric, confined, and isothermal flowfield of a research dump combustor and reported. Measurements of mean velocities, Reynolds stresses, and triple products were carried out at axial distances ranging from 0.38 to 12 step height, or 0.06 to 2 combustor diameters downstream of the dump plane. Detailed experimental data are provided to help in the understanding of the behavior of the turbulent transport characteristics of the confined shear layer inside the combustor. The data from this study will also be available for upgrading or evaluating advanced numerical codes used to predict second-order turbulent flows. The energy terms, convection, diffusion, and production terms, were computed from the experimental data, while the viscous dissipation term was obtained from the balance of the energy equation. The results of a detailed comparison of the present data with similar work reported in open literature show the accuracy and consistency of the present work. It also shows that the general behavior of the flowfield and energy budget results are in excellent agreement with previously reported data. The results indicate that the shear layer flow created by the sudden expansion enhances the combustor performance by serving as a turbulence generator mechanism.