City Research Online

Abstract

A test rig has been constructed for the study of dilute turbulent suspension flow consisting of air and small spherical glass particles in a 3.125 cm copper pipeline. Four particle sizes were used: 35u, 75u, 82u and 380u mean diameter, and the Reynolds number ranged from 40,000 to 80,000 with mass flow ratios of 0.5 to 3.0. A data logging system has also been developed for rapid data recording and processing.

The experimental data of pressure drop measurement show that within the present ranges of mass flow rates and particle sizes, loading of particles would always result in higher pressure drops and to a good approximation, the suspension friction factor can be expressed as a simple function of the mass flow ratio.

Two methods were used for the measurement of electrostatic charges on the particles: the Deflection Method utilizing highspeed photography techniques and the Electrostatic Ball Probe. The charge to mass ratio was less than 10> C/kg and charges of both signs were present on the particles. The charge current was found to be the order of 107 A and was always negative. No correlations were obtained between the pressure drop and charge current data.

The general equations of motion which describe the flow characteristics under the simultaneous influences of gravity, electrostatic, relaxation and diffusion effects are formulated and numerical results of distributions of electric potential, density, velocity, mass flux and diffusivity of the particles have been obtained for various mass flow rates, particle sizes and charge to ratios.

While the effect of electrostatic charging has been shown to be significant on the distribution of particulate density, the distribution of particle velocity is mainly determined by the drag force due to the relative motion between the fluid and the particles. The predicted pipe flow distributions are shown to be in reasonable agreement with experimental results obtained by other workers.

Publication Type:	Thesis (Doctoral)
Subjects:	T Technology > TJ Mechanical engineering and machinery
Departments:	School of Science & Technology > Department of Engineering School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses

Export

Downloads