Summary

A two-component fibre-optic laser Doppler velocimeter (LDV) system has been employed to measure the flowfield characteristics of a confined, isothermal strongly swirling flow in a combustor model. The primary objectives are to understand such complex flowfields and to provide complete benchmark data for comparisons with numerical predictions based on practical models for turbulent swirling flows, and thereby guide the development of such models. For this confined strongly swirling flow, the measurements show the radial velocity component (close to the swirler exit) to be of the same order as the axial and swirl components. Comprehensive and detailed data show a large central recirculation region close to the dump plane which extends beyond the last measurement station. High velocity gradients and high turbulence activities are common for this type of flow and the current set of data confirms these previous findings. Generally speaking, most of the mixing takes place in the shear layer between the annular swirling jet and the corner recirculation region due to the sudden expansion