Effects of cooling flow on the flow structure and acoustic oscillation in a swirl-stabilized combustor. Part II: Acoustic analysis

The effects of cooling flow injection on the flow development and acoustic oscillation in a premixed swirl-stabilized combustor had been numerically investigated using 3D large-eddy simulation. Three different cases, including one with no injection and two with cooling flow injection (5, 20 m s), were simulated. With injection of cooling flow-through slits in the combustor wall, the absolute velocity and vorticity magnitude were found to increase at the central toroidal recirculation zone, whereas they were decreased at the corner recirculation zone, due to the enhanced axial velocity of the main swirl flow. In this study, various flow characteristics resulting from the cooling flow injection were visualized and investigated in detail. The coherent structures and acoustic modes were addressed in Part II.