A numerical investigation of the ignition characteristics of a spray flame under atmospheric conditions

摘要

This study presents a numerical investigation of the characteristics of a transient spray flame ignited by laser-induced breakdown. The simulations are carried out under atmospheric conditions within well defined boundary conditions. The multiphase set-up comprises a kerosene blend as the liquid fuel provided by an air assisted nozzle with droplet velocities up to 40 m/s and an air co-flow with velocities ranging from ～ 1.0 m/s to 4.5 m/s. An initial flame kernel is created by a laser-induced breakdown at the spray cone edge. Onsetting vaporization and further propagation of the flame, largely on the outskirt of the flame cone surface lead to a growing and convected self-sustaining flame. Results concerning the flame growth and the flame center position, representing the major general characteristics of the instationary combustion process are provided. As experimental data is available for the same set-up and boundary conditions, the simulation outcome is further compared with regard to its qualitative and quantitative agreement. The study shows that the employed numerical tools for predicting transient combustion are of very satisfying quality and can subsequently be used for more complex scenarios to evaluate questions concerning flame kernel development and igniter location.