Alternative fuel spray behavior

Abstract

The effects of alternative fuels on the combustion characteristics of a liquid fuel spray are examined. Fuel properties are varied and the effects of these variations on the structure (drop histories, temperatures, and species concentrations) of the spray flame are calculated. Also, a comparison is made of the differences in two spray flames fueled by a standard NATO fuel and a proposed alternative fuel. The calculations are performed using a reacting, two-phase, two-dimensional flow code that utilizes a Lagrangian calculation of droplet trajectories and an Eulerian approach for the gas-phase flowfield. Interactions between the drops and the gas phase are accomplished through the particle-source-in-cell technique with exchange of mass, momentum, and energy between the two phases. A global reaction scheme is used with the reaction rate determined by the minimum of either an Arrhenius rate or mixing rate. Fuel property changes that affect droplet size and volatility are shown to have significant effects on droplet trjectory patterns. However, for the flowfield examined in this paper (where the fuel spray core is very rich and the mixing of air with the fuel occurs at a relatively slow rate), these trajectory changes only moderately modify the fuel vaporization pattern within the spray.more » 20 refs.« less