Numerical simulation on the ignition and combustion of transient sprays.

Abstract

Numerical simulations on the transient sprays were made based on the Eulerian gas and Lagrangian drop formulations incorporated with the chemical reactions of gases and soot. Computed profiles of species and soot concentration, gas temperature, and local heat release rate were presented to understand the overall and internal structure of the spray ignition and combustion. Some of the computed results were compared with the experiments conducted using a rapid compression machine. The results indicated are as follows. (1) The computations predict the ignition delay, the transient configuration of the spray flame and drop penetration distance reasonably well. (2) Ignition is initiated by a hot spot at the off-axis region followed by the rapid spread of the combustion region which induces an intense heat release rate just after the ignition. (3) The drops evaporate in the early stage of the spray combustion. A flame front is formed downstream from the nozzle exit. Near the flame front, the local heat release rate is very intense where premixed combustion occurs. Gaseous turbulent diffusion combustion is dominant in the downstream.