BEHAVIOR OF SOLID PARTICLES IN PULSATING FLOWS

The characteristics of solids particles in pulsating flows are investi gated. A model based on the momentum equation is developed and applied to solid inert particles in the gas flow of the Rijke-type pulsating combustor, by using a computational scheme based on a fourth order Run ge-Kutta method. For application of the model, two types of particles are considered: coal ash and elutriated material from coal combustion. The velocities and trajectories of the particles are obtained, showin g that pulsations decrease the particle residence time and increase th e rate of particulate emission. The decrease in residence time becomes more significant when the particle diameter is close to the cut diame ter, i.e., the diameter for which the particle starts to rise in the a scending gas flow of the combustor. The cut diameter is found to be in dependent of the type of regime, pulsating or non-pulsating. The phase between particle and flow velocities is found to depend on particle s ize and density. For coal-ash-type particles, for example, those with diameters lower than 5 mu m follow the pulsating flow at zero phase an d those with diameter higher than 120 mu m possess a velocity 1/2 pi o ut of phase with the flow velocity. The phase for particles between 5 and 120 mu m will be between 0 and 1/2 pi. (C) 1995 Academic Press Lim ited.