The effect of particles on the acoustic instability under conditions of combustion of pulverized coal

Abstract

A theoretical investigation is performed of the emergence of acoustic vibrations under conditions of combustion of coal particles in the combustor of a pulsed MHD generator. The flow in the combustor is assumed to be one-dimensional under conditions of thorough stirring in the transverse direction and of the absence of stirring in the longitudinal direction. The particles are assumed to be spherical and monodisperse. The drag during the motion of particles relative to gas mixture in the case of acoustic vibrations is determined using the Stokes formula. It is assumed that the combustion of coal particles occurs in the diffusion mode. Approximate formulas are derived for the determination of the increment and frequency of acoustic vibrations, in which the fuel and oxidizer parameters appear explicitly. It is demonstrated that the drag during the motion of particles relative to gas mixture stabilizes the system by significantly reducing the value of increment.