Particle size effects on the particle deposition from non-isothermal stagnation point flows

Abstract

The deposition (transport) of particles onto cold smooth walls (about 1159-1345 K) from high temperature combustion suspensions (about 1565 K) undergoing a two-dimensional stagnation point flow was investigated experimentally for a wide range of particle sizes (having diameter from 0.1 to 30 μm) by SEM (Scanning Electron Microscopy) techniques. Using an LDA (Laser-Doppler Anemometry) system, the velocities of the two-phase and the particle size were measured simultaneously. Particle sizes were measured using the maximum pedestal amplitude of Doppler signal and the visibility. Also, particle motion that considered the effects of thermophoresis and inertial impaction was computed by numerically solving Eulerian partial differential equations of momentum, energy and mass for the gas and particle phases (two-fluid model). The experimental data were compared to the numerical results for variation of Stokes numbers. Good agreements between experimental and numerical results were obtained for velocity, temperature and particle deposition rates. Also, the importance of combined thermophoresis and inertial impaction was examined. © 1991.