Soot formation in monodisperse droplet streams

Abstract

Because of the coexistence of liquid and gaseous fuel phases in an aero engine combustor with typical air blast atomiser the soot formation process cannot be traced back unambiguously to physical effects of the one chemical or kinetical effects of the other phase. The objective of this task was to improve understanding of soot formation and its dependence on droplet properties. Soot formation from a monodisperse droplet stream has been detected in a basic experiment with well defined initial conditions of droplet size, droplet concentration, air fuel ratio, liquid physical properties, etc. An existing experimental test rig has been adapted to study soot formation during the combustion of a monosized droplet stream of hydrocarbon fuel in air. Compounds and composition of the fuel has been defined in another task of this project. The two phase flow was characterised in non reacting conditions by the use of optical techniques. Operating conditions were variable pressure and droplet concentration, and liquid kerosenelike fuels. The analysis of soot appearance and evolution correlated with a parametric variation of operating conditions (pressure, air fuel ratio, residence time, temperature) was realised using laser-induced incandescence (LII).