DETERMINATION OF INERTIAL EFFICIENCIES AND DUST FREE ZONES OF ELECTRICALLY ENHANCED COLLECTORS

ABSTRACT

The determination of particle trajectories when electrostatic forces are present is an important part of analyzing collection efficiency. For small Stokes numbers, an asymptotic expansion of the Fuchs trajectory equation yields a first order differential equation which depends only on spacial variables. Using this equation, trajectories of particles about collectors with an axis of symmetry parallel to the direction of air flow can then be determined by a single numericalintegration. The geometry of the direction field of this equation is analyzed to numerically determine the limiting trajectories which, in turn, yield the efficiency. The same kind of analysis of the saddle points of this direction field in combination with numerical integration can be used to determine those solution paths which bound the dust free zones about the collector.

These ideas are demonstrated by applications to the case of a spherical collector on which there is an electrostatic charge and which is subject to an external electrical field.