THE INTERACTION OF LIQUID REACTING DROPLETS WITH THE PULSATING FLOW IN A RIJKE-TUBE COMBUSTOR

This paper presents the results of a theoretical investigation on the characteristics of a reacting liquid droplet in the self-generated osc illatory flow of a Rijke-pulse combustor. The droplet motion equation, accounting for droplet evaporation due to combustion, was solved usin g a fourth-order, Runge-Kutta method. The model was applied to a Rijke -type, alcohol-fired combustor for which experimental data exist to be used as entrance parameters. The main conclusions derived from this s tudy are (I) for a range of droplet initial velocity, pulsating flames of liquid fuels are shorter than the corresponding steady flames beca use of a reduction in lifetime of droplets with the same initial diame ter in the pulsating flow, (2) for a range of droplet initial diameter , time-resolved heat generation rates from pulsating sprays exhibit a preferred frequency equal to twice the frequency of the pulsating flow , and (3) droplet initial diameter, droplet initial velocity, and loca tion of the spray in the tube influence the excitation and maintenance of acoustic oscillations in a Rijke-type combustor based on evaluatio n of the Rayleigh integral over time and volume in the combustor. The theoretical results presented and discussed herein are supported by ex perimental observations. Copyright (C) 1997 by The Combustion Institut e