Effects of swirling strength on flow characteristics of swirling double-concentric jets with a dual-disk flow controller

The flow characteristics of the swirling double-concentric jets subject to the influence of a dual-disk flow controller were studied experimentally. The instantaneous and time-averaged flow patterns were obtained by laser-light sheet assisted smoke-wire flow visualization method. The velocity characteristics were measured by a hot-wire anemometer. The smoke flow patterns were analyzed by flow topology. According to the flow patterns and the topological flow analysis, four characteristic flow modes-annular jet-dominated wake, central jet-dominated wake, central jet-dominated radial flow, and high-turbulence swirling wake-are identified in the domain of swirling number and central jet Reynolds number. In different regimes of annulus and central jet Reynolds numbers, different complex vortical flow systems were formed to satisfy the flow topology. The annular jet-dominated wake, central jet-dominated wake, and central jet-dominated radial flow appeared in the low swirling annular jet regime. The high-turbulence swirling wake was observed in the high swirling annular jet regime. The high-turbulence swirling wake had significantly larger axial velocities and turbulence intensities.