Turbulence Characteristics in an Axisymmetric Sudden Expansion

Abstract

Simultaneous two-component laser Doppler velocimeter measurements were made in an axisymmetric sudden expansion to measure the flow properties of a confined, isothermal flowfield of a research dump combustor. Measurements of mean velocities, Reynolds stresses, and triple products were carried out at axial distances ranging from 0.38H (H = step height) to 18H downstream of the dump plane. Detailed experimental data are provided to help in the understanding of the behavior of turbulent transport characteristics of a confined shear layer. In addition, the data from this study will be available for upgrading / or evaluating advanced numerical codes used to predict complex turbulent flows. The turbulent kinetic energy terms: convection, diffusion, and production terms were computed directly from the experimental data using central difference, while the viscous dissipation term was obtained from balance of energy equation. The results indicate that the shear layer flow created by the sudden expansion enhances the combustor performance by serving as a turbulence generator mechanism.