Velocity of solid particles entrained with reduced-pressure air flow in horizontal duct.

Abstract

The velocity of glass beads entrained with air flow in a horizontal square duct was measured in a range of pressures: 760-1 mmHg,ua: 10, 18 m/sec, dv\ 81.5-184microns, D: 2.45 cm. It is pointed out that with respect to the flow regions in duct and around particle the present experimental conditions are considerably different from those in previous works at atmospheric pressure. Data obtained under reduced pressure are correlated within ±30 %by the following equation, which includes the Cunninghamcorrection coefficient Cm.(ua -up)/ua = 1.22Cmdpu0aA j/a=air velocity [cm/sec], up -particle velocity [cm/sec], dp =particle diameter [cm].

Mathematical Modeling of Turbulent Transport of Particles in the Boundary Layer of a Tubular Membrane Element

“…Many research works have been devoted to the development of the theory of deposition of micropar-ticles on channel walls in a turbulent flow regime. The studies differ in the mechanism of deposit formation and can be distributed in the following main lines: longitudinal slipping of particles that is commensurate with the velocity of the medium [14,15]; deposition of particles by virtue of inertia from vortices that are close to the walls [16]; interaction of large-scale turbulent eddies with a buffer layer and, as a consequence, convective-inertial deposition of particles [17][18][19][20]; transverse migration of particles [21]; deposition due to the difference in diffusion coefficients near the wall and in the flow core [22][23][24][25]; and others [26].…”