Formation of striped pattern deposition layers by an aerosol flow — analysis of thickness and interval of layers

Abstract

The effects of air velocity and particle diameter on the thickness and the interval of striped deposition layers were studied as a simultaneous phenomenon of particle deposition and reentrainment in a rectangular channel flow. The powders used were alumina of three different sizes ( D p50 = 2.6, 4.9 and 5.6 μm) and the average air velocity was in a range of 10-23 ms −1 (turbulent aerosol flow). The experimental results show that the thickness increases with time elapsed and becomes constant. The time dependence can be represented by an exponential equation. Although the thickness tends to decrease with increasing average air velocity, the variation is small as long as the deposition layers take the striped pattern. The velocity range showing the striped pattern shifts to higher velocity for smaller particles. Furthermore, the interval between the striped deposition layers increases with average air velocity and/or particle diameter. It is suggested that the particle inertia takes an important role in the formation of the striped deposition layers.