Effect of acoustic levitation force on aerodynamic particle removal from a surface

The flow field generated by a downward-facing annular slot jet with a circumferential velocity component and a vacuum outlet port confined between two horizontal planes is referred to as a bounded vortex. A bounded vortex can be used to aerodynamically transport particles from a surface, allowing cleaning of a dust-covered surface without making physical contact with the surface. This paper reports on the influence of acoustic levitation on the efficiency of particle transport from the surface by a bounded vortex flow. The study is conducted by placing four identical speakers symmetrically around a vortex-generating nozzle and aiming the speakers toward the point on the plate directly under the nozzle center. The distance between each individual speaker and the target glass plate surface and the frequency of the acoustic wave are chosen to produce a standing acoustic pressure wave along the vertical direction and its acoustic pressure antinode plane located at the glass plate. The pressure standing wave creates a levitating force that is strong enough to overcome the van der Waals adhesive force between the dust particles and the glass plate and lift the particles from the glass plate. The effect of this acoustic forcing on different aspects of particle mitigation is examined. It is found that for certain flow and acoustic parameters, acoustic forcing can significantly increase the efficiency and usefulness of the bounded vortex particle mitigation method.