Measurements and Calculations of Preheated and Unpreheated Confined Kerosene Spray Flames

Abstract

Measurements of mean temperature, concentrations of unburned hydrocarbon, carbon monoxide, carbon dioxide and oxygen and of velocity have been obtained in a series of confined kerosene-spray flames. They quantify the influence of mean droplet diameter in the range from 54 to 115 μm, of swirl number in the range from 0.47 to 1.4 and of combustion air temperature in the range from 20 to 225°C. Four flame configurations are identified and correspond to: high swirl, high temperatures and small droplets with consequent droplet evaporation in the recirculation region; larger droplets which penetrate the recirculation region and result in combustion close to the combustor wall; intermediate swirl so that droplets of all sizes penetrate the recirculation region and move upstream and downstream to burn; and weak swirl where the flame is stabilized close to the wall and the main flame extends further downstream. Calculated results are also reported and allow the magnitude of associated uncertainties to be quantified. The inadequacy of the physical information used to support droplet models is emphasized for the larger droplets. With droplet diameters of less than 50 μm, and increasing with preheat temperature, droplet models are unnecessary.