| The deposition of fine particles is not only one of those significantphenomena related to basic physics, but also plays an important role in practicalapplications such as the dust capture and removal, the ash fouling and slagging,the blade erosion of gas turbine, etc. Nowadays, the development of advancedtechnologies of clean energy pursues much higher temperature and higherpressure. Therefore, the attention has been paid to the problem of fine particledeposition in such a harsh condition. In this paper, the study of the impactionand adhesion mechanism of fine particles with a flat surface under hightemperature is helpful to conduct engineering applications.First, several types of inertial impactors were investigated, so as to studyinertial impaction mechanism. The correlations between Stokes number andimpaction efficiency were compared. Among all kinds of impactors, theconventional impactor was selected to be used for the experiments, and anexperimental set-up was subsequently built.Both monodisperse polystyrene particles and polydisperse fly-ash particlesimpacting a stainless-steel plane surface were studied, with different flow fieldcharacteristic velocity and temperature. For polystyrene particles, the resultsindicated that the sticking efficiency of the particles decreased with theincreasing characteristics fluid velocity, and increased with the increasingtemperature. Similar conclusions were found for the polydisperse fly ashparticles.The dynamic adhesive contact model for a single particle was established,which then compared with either the incident velocity achieved from theComputational Fluid Dynamics and Discrete Phase Model, or the criticalsticking velocity calculated from JKR model. This experimental methoddeveloped here was proved to predict the sticking efficiency of polystyreneparticles within a coarse range, and it would predict more accurately for fly ashparticles. The applicability and way to improve the accuracy of the method havealso been discussed. |
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