The effect of height variations on cyclone performance under fluctuating boundary conditions.

[Display omitted] • Applying fluctuation to the cyclone boundaries to consider the actual condition. • Dominant frequency in non-uniform flow is independent of the vortex finder height. • Enlarging the vortex finder length increases the vortex power in the cylinder zone. • Applying the oscillations has strengthened the vortex power in non-uniform flow. • In non-uniform flow, the efficiency is independent of the vortex finder length. This study has been investigated the effect of the height variation of the cyclone components under the non-uniform flow. Oscillating flow is an approach to consider the real flow condition in the use of cyclones as an inlet air filter for the internal combustion engine. Accordingly, an oscillating flow with an inlet velocity of 15 (m/s) along with a range of pressure based on the motor inlet is applied to the cyclone's dirty and clean outlets. Seven cyclone models including a base model, and models with height change in vortex finder, cylinder, and cone have been created and gridded. The numerical solution has been run using the Large Eddy Simulation and the Eulerian–Lagrangian model. Having validated, the flow field and cyclone performance have been considered. The results indicate that under the non-uniform flow, a decrease in the vortex finder height and an increase in the height of the cyclone's cylinder and cone minimize the pressure drop. Applying oscillations along with the 30% change in the vortex finder height increases vortices power in the cone, cylinder, and vortex finder zones by 4.23, 8.99, and 21.42 percent, respectively. Additionally, the efficiency dependence on the change in length of cyclone components under the uniform flow is much higher than that of under the non-uniform flow. [ABSTRACT FROM AUTHOR]