고온의 기체-입자 유동으로부터 입자부착 현상에 관한 실험적 연구

Abstract

Experimental studies of particle (TiO2) deposition from the laminar hot gas particle flow (about 1565K) onto the cold wall surface (about 1215K∼1530K) were carried out by the ``real time`` laser light reflectivity method(LLRM) and the photographs of scanning electron microscope(SEM). The LLRM was used for the measurement of thermophoretic deposition rates of small particles (dp<3μm), and the photographs of SEM were used for determining what factors control the collection of particles having diameters ranging from 0.2 to 30 microns. Two phenomena are primarily responsible for transport of the particles across the laminar boundary layers and deposition: (1) particle thermophoresis (i.e. particles migration down a temperature gradient), and (2) particle inertial impaction, the former effect being especially larger factor of the particle deposition in its size over the range of 0.2 to 1 microns. And also, this study indicates that thermophoresis can be important for particles as large as 15 micros. Beyond dp=16μm, this effect diminishes and the inertial impaction is taken into account as a dominant mechanism of particle deposition. The results of present experiments found to be in close agreement with existing theories.