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Engineering Mathematics
Review of Viscous Flows
Review of Computational Fluid Mechanics

Particle Adhesion
Simulation Methods
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The National Science Foundation
ME 437 The National Science Foundation
 Aerosols
Introduction to Aerosols | Drag, Lift Forces | Aerosol Kinetics | Virtual Mass, Basset Forces & BBO Equation | Nonspherical Particles | Brownian Motions | Particle Deposition Mechanisms | Electrodynamics | Aerosol Coagulation |

Particle Deposition Mechanisms: Impaction

Cyclone Separator

Cyclones are used for removal of particles with diameter more than a few microns from gases. Gas enters from the side and acquires a rotational speed. Particles are moved towards the wall due to centrifugal forces.

Radial force balance for a particle in the rotating flow in a cyclone is given as

(1)

For small particles, , it follows that

(2)

or

(3)

where  is used.

It is assumed that

(4)

Equation (3) then becomes

(5)

or

(6)

The number of turns needed to deposit the particles of size d (that is, moving the particles from the radius a to the side wall at r=b) is given by

(7)

or

(8)

Alternatively, the smallest particle that can be removed in  turns is given by

(9)

In practice, an approximate expression

(10)

is used, where U is the mean inlet velocity.



Dr. Goodarz Ahmadi | Turbulence & Multiphase Fluid Flow Laboratory | Department of Mechanical & Aeronautical Engineering
Copyright © 2002-2005 Dr. Goodarz Ahmadi. All rights reserved.
Potsdam, New York, 13699
ahmadi@clarkson.edu