CFD simulation of the flow pattern and separation performance in swirl tubes

A three-dimensional computational fluid dynamics (CFD) model through swirl tubes was developed to obtain the flow pattern and separation behavior in swirl tubes. The problem of modeling highly swirling flow is overcome by means of Reynolds stress model (RSM). The tangential velocity profile, a key flow parameter in swirl tubes, display classic Rankine vortex. Importantly, some flow characteristics which affect the performance of swirl tubes were identified. It is presented the downward rotating flow goes against with the upward flow near the opening vortex finder, resulting in a short-circuiting flow. At the bottom of the swirl tube, where exists much high radial velocity, the gas will return from dust hopper to form eddy flow. A Lagrangian method is employed to track the particle motion and calculate the gas-solid collection efficiency in swirl tubes. The CFD results agreed well with the experimental data. The results indicate that the CFD method can effectively reveal the mechanism of gas-solid flow and separation in swirl tube.