Particle Transport Across the Transpired Turbulent Boundary Layer

Abstract

The results of the experimental and theoretical investigation are presented to determine the effects of surface inclination and density of particulates on deposition control by transpiration. Effects of the particle size and injection rate were reported in a recent paper by Kozlu and Louis (1986). The purpose of this work is to obtain a better insight into the deposition process by investigating the different aspects of the problem. An application of the work is the control of deposition of small particles (0.5–3 μm) contributing most of the mass of the solid carryover entering turbines burning fuels derived from coal. Experimental study is carried out in a wind tunnel facility containing a porous transpired section. Similar flows and particle motions are achieved by choosing the proper Reynolds and Stokes numbers which are representative of the conditions found in industrial gas turbines. The study after reviewing the effects of size and injection rates on deposition determines the interaction between transpiration and the inertial impaction of particulates using the glass particles. Tests were also conducted on the inclined plate with coal particles to determine the density effects on the particle concentration profiles and consequently on the arrival rates. Experimental data are used to predict the concentration profiles of particulates for different density values. For inclined plate experiments, the turbulent Schmidt numbers obtained from the experiments are in agreement with the theoretical prediction of Tchen (1947) as found in the flat plate.