Atomization of Crude and Residual Fuel Oils

Abstract

A study is made of the effects that fuel properties have upon the mean droplet size characteristics of three fuel atomizer types that are commonly employed in the gas turbine engine. The fuels tested included kerosine, gas oil, and a heavy residual fuel oil, and each was passed through a pressure swirl jet, a prefilming airblast, and a plain-jet airblast atomizer in turn. Tests were carried out at pressure levels close to ambient and mean drop sizes were determined using a light-scattering technique. Two main points emerge from the results: Firstly, for all atomizers tested, that the existing dropsize correlations are not sufficiently accurate for use with the high-viscosity residual fuel oils. Secondly, that the fuel dropsize decreases with the change in atomizer type from plain-jet airblast to prefilming airblast. The difference in performance of the two types of airblast atomizers is most noticeable for the residual fuel oil, particularly so at pressure drop levels of less than around five percent. Use is also made of the many data points collected to derive improved dropsize correlations which may be used over the whole range of fuels tested.