Adherent Particles in Relation to Surface Shape and Dimensions

Detachment of Adherent Particles in Relation to Surface Shape and Dimensions 

The detachment of adherent particles from spherical, cylindrical, and other surfaces has a number of special features. These features stem from the fact that when a flow passes over such surfaces, not only does the boundary layer structure vary, but this layer may separate from the surface. Hence, the removal of adherent particles from such surfaces will not be uniform across the surface. As an illustration, data are shown in Fig. X.5 for the detachment of adherent particles from a cylindrical surface by an air stream. 

The maximum detachment (minimum value of 7 ) is observed at values of of 90 to 270° fewer particles are removed from the frontal part ((/ = 0°), and no particles are detached from the backside at these particular velocities. As the flow velocity is increased (curves 2-5), the adhesion number drops off. Under 

Detachment of Equal Number of Particles. Isopures. When an air flow is passing over a dust-covered surface, the structure of the boundary layer will not be the same for all parts of the surface. This in turn brings about a situation in which the degree of removal of adherent particles will be different for different parts of the surface. If we break up the surface into zones, we can evaluate the removal of adherent particles from certain small zones of the surface for which the parameters of the air flow and the structure of the boundary layer remain practically unchanged. This enables us to calculate local coefficients of removal 

In Fig. X.5 we show isopures for the detachment of particles from a cylindrical surface. These curves connect surfaces with identical adhesion numbers or coefficients of removal. 

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