Numerical simulation of roughness effects inside a brick-lined cyclone separator
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NAFEMS Seminar Simulation of Complex Flows - Applications and Trends
An industrial cyclone, which is used for dust separation from a hot gas mixture, is studied by means of numerical simulation. Because of high gas temperatures (about 1075 K), the inner surfaces of the cyclone separator and the inlet pipe have to be lined with refractory bricks, which cause high wall roughness. The virtual wall model is used to simulate this roughness, and a new model extension accounting for joints between the bricks is proposed and validated by dedicated experiments.
As the cyclone inlet mass load is relatively low (0.01 kg/kg), the Eulerian-Lagrangian approach is used for the simulations. The continuous phase conservation equations are solved in the Eulerian reference frame on a fixed grid, whereas the discrete phase properties are resolved by computing particle trajectories through the computational domain in a Lagrangian reference frame.
Besides an inlet particle diameter spectrum ranging from 1 µm to 100 µm, also different particle materials with different particle densities have to be considered. The measurements and the analytical Muschelknautz model are compared to the numerical simulations regarding pressure loss, particle spectra at the outlet and the fractional separation efficiency.
The Muschelknautz model shows some difficulties with the kind of wall roughness considered here (especially joints between the bricks). Additionally, this method was not designed for different particle densities simultaneously.
Nevertheless, comparisons show a good agreement between numerical simulations, measurements and theory.