AN ISOTHERMAL EXPERIMENTAL INVESTIGATION OF TURBULENCE TRANSPORT THROUGH AN ABRUPT AXISYMMETRICAL EXPANSION

A non-intrusive, two-component laser Doppler velocimeter was employed to measure the flow properties of a confined, isothermal, swirling flo wfield in an axisymmetric sudden expansion research combustor. A const ant angle swirler was used to stir the flow at the inlet of the combus tor. Measurements of mean velocities, Reynolds stresses and triple pro ducts were carried out at axial distances ranging from 0.38 H (step he ight) to 18 H downstream of the swirler. Detailed experimental data ar e provided to help in the understanding of the behaviour of swirling, recirculating, axisymmetric and turbulent flows. Also, these detailed experimental data will be available for upgrading advanced numerical c odes. The turbulent kinetic energy terms, convection, diffusion and pr oduction, were computed directly from the experimental data using cent ral differencing, while the dissipation term was obtained from an ener gy balance equation. The swirling flow data are compared with the simp le dump flow in the same experimental arrangement and it is shown that swirl enhances the production and distribution of turbulence energy i n the combustor which, in turn, indicates thorough flow mixing and ear lier flow recovery.