High-Energy-Density Fuel Blending Strategies and Drop Dispersion for Fuel Cost Reduction and Soot Propensity Control

Abstract

High-energy-density (HED) liquid fuels have high soot propensity and are expensive. The idea of mitigating these characteristics by adding a less expensive, low soot propensity liquid fuel to the HED is tested through numerical simulations. The model represents an axisymmetric, polydisperse, dense cluster of binary-fuel (solvent/solute) spherical drops embedded into a vortex. Since soot propensity depends on the partial density of the evaporated fuel, this partial density is compared for uncharged and electrostatically charged drops; charging is used here as an effective way to increase dispersion and reduce sooting propensity. Results from the simulations show that while the solvent soot propensity indeed decreases with drop charging, contrary to simplistic expectations, addition of HED as a solute increases sooting propensity of the solute with increased drop dispersion. This is due to the additional dispersion maintaining the slip velocity at the drop surface and preferentially evaporating the solute. These counterintuitive but correct physical effects are independent of the initial solvent/solute mass ratio, and the soot propensity decreases with decreasing solute volatility. Based on these results, blending strategies are suggested for minimizing sooting propensity and decreasing fuel costs.