EFFECT OF LIQUID FUEL DROPLET SIZE ON SOOT EMISSION FROM TURBULENT SPRAY FLAMES.

The present study is concerned with the effect of fuel droplet size on the complex soot process in a turbulent liquid-fuelled combustor. A hybrid Eulerian-Lagrangian method is employed to model the reactive flowfield inside the combustor. Equations governing the gas phase are solved by a control-volume based semi-implicit iterative procedure, while the time-dependent differential equations for each size of the fuel droplets are integrated by a semi-analytic method. The processes leading to soot consist of both formation and combustion. Soot formation is simulated using a two-step model, while a finite rate combustion model with the eddy dissipation concept is implemented for soot combustion. Also, mathematical models for turbulence, combustion, and radiation are used to take into account the effects of these processes. Results reveal the significant influence of liquid fuel droplet size on soot emission from turbulent spray flames under different equivalence ratios, inlet air temperatures, and combustor wall temperatures. The predictions show that reduction of spray droplet size considerably decreases soot emission from spray flames.