K. Shuster

The effect of centreline particle concentration in a wave tube

The interaction of sound waves with an aqueous suspension of solid particles was analysed experimentally and theoretically. A heretofore unreported effect of particle concentration in the vicinity of a wave-tube centreline was observed. The phenomenon is related to the combined effect of Rayleigh-type acoustic streaming, jet-like streaming (quartz wind) and drift forces occurring in the presence of a sonic wave in the suspension-filled tube.

Agglomeration of submicrometer particles in weak periodic shock waves

Agglomeration of submicrometer particles in the presence of acoustic fields was treated experimentally. Fast agglomeration of aerosol particles in weak periodic shock waves was observed. The rate of particle agglomeration in shock waves was found to be much faster than in continuous sound waves.

Particle motion in simple shear flow with gravity

The motion of aerosol particles in simple shear flow, subject to gravity, is analyzed. The combination of gravity and shear-induced lift is shown to give rise to particle drift. It is shown that in shear flow near a wall, when gravity points in the direction of flow, particles drift towards the wall, while for gravity pointing against the flow the drift is away from the wall. These results are also demonstrated experimentally, with fair qualitative agreement between analysis and experiments.

ELECTROSTATIC POROUS FILTER WITH A BLOCKING ELECTRODE

Abstract This work proposes to add to an electrostatic filter an auxiliary blocking electrode, charged by the same charge as the particles. The effect of the blocking electrode is to increase the collection efficiency of the electrostatic filter. Experiments performed on an electrostatic filter equipped with a permeable blocking electrode indicate that such an electrode roughly doubles the collection efficiency of the filter. A mathematical model was developed to account for the effect of the blocking electrode. The model facilitates calculations of the major parameters of the electrode, as part of a design of a more efficient electrostatic filter.

Enhancing the efficiency of the electrostatic filter

This work considers the increase of the collection efficiency of the electrostatic filter by the installation of a blocking permeable electrode. This electrode is placed at the outlet of the collection zone and is charged by the same charge as the particles. The electrostatic force, which is generated by the blocking electrode, acts on the particles in a direction generally opposite to that of the gas flow, resulting in stronger curvatures of the particle trajectories, leading to higher capture efficiencies.